Papers - Isobe, Tetsuhiko

Fabrication of CuInS<inf>2</inf>/ZnS quantum dot nanocomposite films and investigation of their influence on performance of soda glass-based luminescent solar concentrators

Yu Imakiire, Yoshiki Iso, Tetsuhiko Isobe

Journal of Materials Chemistry C (Royal Society of Chemistry)  13 ( 8 ) 4078 - 4088 2025.02

Research paper (scientific journal), Joint Work, Accepted,  ISSN  20507526

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The power generation performance of luminescent solar concentrators (LSCs) is decreased by unignorable optical losses including self-absorption of luminescence by the phosphor and optical absorption by the light guide plate. To address the optical loss due to self-absorption, this research focused on the use of core/shell CuInS2 (CIS)/ZnS quantum dots (QDs) with a large Stokes shift. The QDs were dispersed in ethylene-vinyl acetate (EVA) copolymer to fabricate transparent fluorescent nanocomposite films. LSCs were prepared with the nanocomposite films and soda glass plate, a common building material to investigate the effect of optical absorption by the light guide plate on the power generation performance. Synthesized QDs showed yellow emission at 587 nm with a high photoluminescence quantum yield (PLQY) of 61.1%, and their large Stokes shift of 0.82 eV reduced self-absorption, making them suitable for LSC applications. We evaluated the effects of QD concentration, film thickness, light guide plate material, and film position on the performance of the LSCs. Optimized performance was observed at a QD concentration of 6.2 wt% and film thickness of 324 μm, showing 1.71-fold higher photocurrent and 3.58-fold larger area of incident photon-to-current efficiency spectrum compared to without film. Replacing soda glass with low-absorption white glass increased power generation by fourfold. This reveals the significant absorption losses of the PL and scattered incident light by soda glass. Despite the considerable optical loss, soda glass is a necessary component in a light guide plate to promote the use of LSCs as building materials. Our findings indicate that QDs with a narrow emission peak at ∼520 nm are required to minimize the absorption loss by soda glass.

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Greenish yellow-emitting carbon dot-based films for luminescent solar concentrator applications

Yunxiang Liu, Yoshiki Iso, Tetsuhiko Isobe

Journal of Materials Chemistry C (Royal Society of Chemistry)  13 ( 2 ) 786 - 792 2025.01

Research paper (scientific journal), Joint Work, Accepted,  ISSN  20507526

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Currently, most carbon dots (CDs) are synthesized from carbon-based materials in autoclaves with high pressure, and then applied in various fields. This work explored the facile synthesis of CDs at atmospheric pressure, which were then purified and embedded in the ethylene-vinyl acetate (EVA) copolymer to form CDs@EVA films and applied in luminescent solar concentrator (LSC) devices. First, crude CDs were synthesized by refluxing p-phenylenediamine (p-PD) in diphenyl ether at 250 °C for 2 h under ambient air conditions, followed by purification using silica gel column chromatography to obtain purified CDs with a photoluminescence (PL) quantum yield of 56% and an average particle size of 15.1 ± 4.4 nm. The CDs@EVA films were fabricated at CD concentrations of 0.05 wt%, 0.10 wt%, and 0.15 wt%, and their thickness was varied from ∼100 μm to ∼500 μm. The yellowish-transparent CDs@EVA films exhibited greenish-yellow emission with absorption peaks at 350 nm and 470 nm, corresponding to the n-π* transition of C=N bonds and the π-π* transition between the highest occupied molecular orbital and the lowest unoccupied molecular orbital of π-conjugated electrons. The PL intensity reached its maximum at 0.05 wt% CD concentration and 408 μm thickness due to self-absorption of emission from CDs. According to the current-voltage curve measurements under AM1.5G simulated sunlight, this film exhibited the maximum short-circuit current (Isc) and power conversion efficiency (η) of the LSC device. Additionally, incident photon-to-current efficiency spectrum measurements revealed that the enhanced Isc and η in CDs@EVA films mainly resulted from emission by absorption through the n-π* and π-π* transitions.

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Photoluminescence enhancement of 1,2,4-triaminobenzene molecules by modification with hydrolytically polycondensed 3-aminopropyltriethoxysilane

Haowei Tan, Yoshiki Iso, Tetsuhiko Isobe

Journal of Luminescence (Elsevier)  277   120980 2025.01

Research paper (scientific journal), Joint Work, Accepted,  ISSN  00222313

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Small-molecule dyes with longer wavelength and higher photoluminescence quantum yield (PLQY) in water have attracted increasing attention due to their bright potential in fluorescence analysis technologies. Here, a red-emitting fluorescent dye of 1,2,4-triaminobenzene (TriAB) was modified with 3-aminopropyltriethoxysilane (APTES) to avoid contact with water molecules and to suppress fluorescence quenching due to O-H vibrations in water. The formation of a silica-like structure from hydrolytically polycondensed APTES was confirmed by X-ray diffractometry and Fourier-transform infrared absorption spectroscopy. Modification of TriAB with hydrolytically polycondensed APTES induced orange emission in the powder state, although TriAB powder did not exhibit any fluorescence before modification. The PLQY of APTES-modified TriAB in water was 11.1 %, which was higher than that of TriAB in water, 4.5 %. These results confirmed that the APTES derived silica-like matrix shielded TriAB from both water and intermolecular interactions with other TriAB molecules, overcoming fluorescence quenching.

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Implications for applicability of the photodegradation and self-recovery of green-emitting CsPbBr<inf>3</inf> perovskite nanocrystals

Yoshiki Iso, Shunsuke Saito, Hikari Toyoda, Tetsuhiko Isobe

RSC Advances (Royal Society of Chemistry)  14 ( 36 ) 26059 - 26065 2024.08

Research paper (scientific journal), Joint Work, Accepted

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CsPbBr3 nanocrystals (NCs) synthesized by the conventional hot-injection method are photochromatic luminescent nanomaterials due to the photoinduced desorption and re-adsorption of the surface ligands. The apparent color and the luminescence intensity were changed significantly during excitation light irradiation and following dark storage; however, the emission wavelength was almost retained. This work investigates the change in emission color of light-emitting diode lighting using the CsPbBr3 NCs to realize photochromatic luminescence. The results showed definite shifts in emission color caused by changes in optical absorption and green luminescence intensity of the NCs, potentially broadening the application feasibility of CsPbBr3 NCs as photochromatic luminescent nanomaterials.

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Open system massive synthesis of narrow-band blue and green fluorescent graphene quantum dots and their application in water sensing

Yukino Ochi, Ayano Otani, Rika Katakami, Akihiro Ogura, Ken-ichi Takao, Yoshiki Iso, Tetsuhiko Isobe

Journal of Materials Chemistry C (Royal Society of Chemistry)  12 ( 18 ) 6548 - 6558 2024.04

Research paper (scientific journal), Joint Work, Accepted,  ISSN  20507526

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Graphene quantum dots (GQDs) are environmentally friendly fluorescent carbon-based nanomaterials. However, there is no report on the massive synthesis of GQDs with narrow-band fluorescence and a high photoluminescence quantum yield (PLQY) using a simple liquid-phase method under atmospheric conditions. In this study, GQDs were successfully synthesized in ∼100% product yield by heating phloroglucinol (PG) with Na3PO4·12H2O in 1,2-pentanediol at 180 °C for 6 h in an open system with air flow, followed by dialysis purification. The high product yield was attributed to the addition of Na3PO4·12H2O as a base catalyst, which promoted the dehydration-condensation reaction between PG molecules. The dispersion of PG derived GQDs (PG-GQDs) in ethanol resulted in blue fluorescence with a full width at half maximum of 32 nm and a PLQY of 54%. Further purification of PG-GQDs by silica gel column chromatography improved the PLQY to 75%. Fourier-transform infrared spectroscopy, 1H nuclear magnetic resonance spectroscopy, and X-ray photoelectron spectroscopy confirmed that dehydration-condensation reactions occurred not only between PGs but also between GQDs and 1,2-pentanediol. The binding of 1,2-pentanediol to the edges of GQDs suppressed the stacking of GQDs and prevented concentration quenching, resulting in a high PLQY. PG-GQDs exhibited negative fluorescence solvatochromism, i.e., the fluorescence wavelength blue-shifted with increasing solvent polarity. Dispersion of PG-GQDs in N-methyl-2-pyrrolidone (MP) resulted in green fluorescence with a PLQY of 96%. Dispersion of PG-GQDs in water resulted in blue fluorescence and a low PLQY of 6% at pH 7, while the PLQY was more than 50% at pH ≥ 11. Using these properties, the sensing of water (pH 13) in MP was investigated. The results showed that as the water content was increased from 0% to 100%, the fluorescence color gradually changed from green to blue and the fluorescence wavelength continuously shifted from 514 nm to 466 nm, indicating their applicability in water sensing.

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Eco-Friendly Electrophoretic Deposition of Fluorescent Nanocomposite Films in an Aqueous Dispersion of Hydrophilized Core/Shell CuInS2/ZnS Quantum Dots for Optoelectronic Applications

Asshu Morimoto, Yoshiki Iso, Tetsuhiko Isobe

ACS Applied Materials & Interfaces (American Chemical Society)  16 ( 6 ) 7780 - 7789 2024.02

Research paper (scientific journal), Joint Work, Accepted,  ISSN  19448244

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Low-toxic and efficient fluorescent core-shell CuInS2/ZnS (CIS/ZnS) quantum dots (QDs) are good candidates for optoelectronic device applications. They are synthesized in a hydrophobic environment, while large amounts of organic solvents used in the preparation of fluorescent films have significant problems on environmental load and human health. CIS/ZnS QDs hydrophilized by adsorbing 3-mercaptopropionic acid on their surfaces can be used in the aqueous film fabrication process. In this work, the aqueous electrophoretic deposition (EPD) of the hydrophilized QDs with silicone-modified acrylic resin nanoparticles was performed to fabricate fluorescent nanocomposite films. The hydrophilized QDs and resin nanoparticles were simultaneously dispersed in basic aqueous solutions due to electrostatic repulsion resulting from their negatively charged surfaces. Transparent films were obtained on a transparent conductive substrate at the anode side by the EPD. They showed yellow fluorescence of the QDs. The thickness increased with increasing the deposition time; however, hemispherical holes attributed to oxygen gas generated by water electrolysis were observed at the longer time. The electron microscopy revealed that the films were densely and homogeneously deposited. The QDs were dispersed around the resin nanoparticles without aggregation. The fluorescence (FL) quantum yield was 43%. The optical absorption peak and FL intensity of the QDs increased accompanied by the film growth. The nanocomposite film showed good heat resistance at 80-120 °C for 5 h; therefore, the prepared films have feasibility in white light-emitting diode (LED) applications. A lightening device structured with the obtained EPD film placed on a blue LED successfully emitted white light. In addition, the flexibility of the nanocomposite film was demonstrated. The aqueous EPD method would be one of the suitable methods for the industrial production of fluorescent QD films. This technique can be applied to other hydrophilic fluorescent QDs with charged surfaces. Realization of various fluorescent QD films would expand the application possibilities.

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Improved photoluminescence of di, tri, and tetra-aminobenzene molecules hydrogen-bonded by polyethyleneimine and their application for metal ion sensing

Tan H., Iso Y., Isobe T.

Journal of Luminescence (Journal of Luminescence)  266 2024.02

Joint Work,  ISSN  00222313

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Higher photoluminescence quantum yield (PLQY) is always a required property for fluorescent molecule dyes used as probes in aqueous environment because of non-radiative relaxation via O–H vibrations. 1,2,4-triaminobenzene (TriAB) dihydrochloride has been reported as a red-emitting fluorescent dye, although its photoluminescence (PL) intensity is very low. Here, a bright orange-emitting fluorophore was prepared by simply mixing TriAB and polyethyleneimine (PEI) in water at pH 7 and applied to metal ion sensing. The PLQY was increased from 3.1 % to 10.0 % by the addition of PEI into an aqueous TriAB solution. Our experiments by exchanging H2O for D2O and changing the pH from 7 to 1 revealed that the role of PEI in enhancing the PL intensity is attributed to the interaction between the amino groups of TriAB and PEI via hydrogen bonding, the prevention of contact between TriAB and water molecules, and thus the suppression of the non-radiative relaxation via O–H vibrations of H2O. We further demonstrated this role for 1,4-diaminobenzene and 1,2,4,5-tetraaminobenzene.

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Assembly-promoted repeatable enhancement of photoluminescence from cesium lead tribromide nanocubes under light illumination

Hashimoto S., Watanabe H., Iso Y., Oaki Y., Isobe T., Imai H.

Nanoscale Advances 6 ( 22 ) 5563 - 5567 2024

Joint Work,  ISSN  2516-0230

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A repeatable enhancement of the photoluminescence (PL) from CsPbBr3 nanocubes (NCs) is promoted by the assembling of NCs. The PL quantum yield (QY) of ordered NC arrays increases with photoirradiation and decreases in the dark. The repeatable enhancement of the PLQY cannot be observed from isolated NCs. The nanospaces between NCs in the ordered arrays allow a reversible change in thermally stimulated desorption and photo-induced adsorption of surface ligands that affect the PLQY.

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Surface Modification Strategy for Yellow-Emitting Carbon Dots in Fluoropolymer Films

Washio K., Sato K., Iso Y., Isobe T.

ECS Journal of Solid State Science and Technology (ECS Journal of Solid State Science and Technology)  12 ( 7 )  2023.07

Joint Work,  ISSN  21628769

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Carbon dots (CDs) were prepared from p-phenylenediamine, modified with trifluoroacetic acid, and dispersed in a fluoropolymer (FP) film. Unmodified CDs did not disperse well in the FP film, resulting in concentration quenching; whereas surface modification improved the affinity between the CDs and the FP, resulting in a homogeneous dispersion and an improved photoluminescence quantum yield.

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Effects of Perfluorodecanoic Acid on the Photostability and Self-Recovery of Cesium Lead Bromide Nanocrystals

Kano K., Iso Y., Isobe T.

ECS Journal of Solid State Science and Technology (ECS Journal of Solid State Science and Technology)  12 ( 5 )  2023.05

Joint Work,  ISSN  21628769

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Photoinduced desorption of surface ligands causes photodegradation of nanophosphors due to enhanced non-radiative relaxation, which is attributed to generated surface defects. We previously reported the self-recovery of photodegraded CsPbBr3 nanocrystals (NCs) and revealed that its mechanism can be attributed to readsorption of the desorbed surface ligands. Thus, using different surface ligands would change the photodegradation and subsequent self-recovery behaviors. Accordingly, in the present work, perfluorodecanoic acid (PFDA) was added to pre-synthesized CsPbBr3 NCs modified with oleic acid and oleylamine to evaluate its effects on photodegradation and subsequent self-recovery. The as-prepared NCs (OA-NCs) and PFDA-modified NCs (PFDA-NCs) were dispersed in nanocomposite ethylene-vinyl acetate resin films to suppress concentration quenching. OA-NCs showed monotonical photoluminescence (PL) decrease under blue excitation light and self-recovery during subsequent dark storage. In contrast, the PFDA-NCs exhibited temporary PL enhancement under excitation irradiation. The photo-activation is attributed to optimization of the adsorption states of the surface ligands in the early stage, while the influence of photodegradation due to ligand desorption becomes dominant later. However, increased PFDA modification prevented self-recovery, indicating that desorbed PFDA may be resistant to readsorption on the NC surface.

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Enhanced and stabilized photoluminescence of perovskite cesium lead bromide nanocubes through ordered assemblies

Sasaki M., Hashimoto S., Iso Y., Oaki Y., Isobe T., Imai H.

Nanoscale Advances (Nanoscale Advances)  5 ( 9 ) 2553 - 2557 2023

Joint Work,  ISSN  2516-0230

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This work clarified the effects of self-assembly of perovskite cesium lead bromide (CsPbBr3) nanocubes (NCs) covered with didodecyldimethyl ammonium bromide (DDAB) on photoluminescence (PL) properties. Although the PL intensity of isolated NCs was weakened in the solid state even under inert conditions, the quantum yield of PL (PLQY) and the photostability of DDAB-covered NCs were drastically improved by the formation of two-dimensional (2D) ordered arrays on a substrate. The PLQY of the 2D arrays increased to ca. 60% by initial excitation illumination at 468 nm and was maintained for over 4000 h. The improved PL properties are attributable to the fixation of the surface ligand around the NCs in the specific ordered arrays.

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Open system synthesis of narrow-bandwidth red-fluorescent carbon quantum dots with a function of multi-metal ion sensing

Katakami R., Sato K., Ogura A., Takao K.I., Iso Y., Isobe T.

Journal of Materials Chemistry C (Journal of Materials Chemistry C)  11 ( 12 ) 4143 - 4152 2023

Joint Work,  ISSN  2050-7526

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Carbon quantum dots (CQDs) are environmentally friendly phosphors. However, there have been few reports on red-emitting CQDs with narrow-bandwidths, all of which were synthesized via solvothermal methods using autoclaves. Here, red-emitting CQDs were synthesized from 4,6-diaminoresorcinol dihydrochloride (DAR), which is an aromatic compound with electron-donating hydroxy and amino groups. The synthesis involved heating at 180 °C for 6 h in a high-boiling-point 1,2-pentanediol solvent in an open system without using autoclaves and catalysts. The DAR-derived-CQDs in ethanol exhibited red photoluminescence with a 0.14 eV full width at half-maximum that was comparable to that of narrow-bandwidth blue-fluorescent phloroglucinol (PG)-derived-CQDs. The red emission was attributed to a weakened quantum-size effect and electron-donating NH2 groups. The hydroxy groups of PG-derived-CQDs interacted with Al3+ and Fe3+ ions, resulting in fluorescence quenching. DAR-derived-CQDs have hydroxy and amino groups, which facilitate the fluorescence quenching for Al3+, Fe3+, Cu2+, and Pb2+ ions.

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Improving the thermal resistance of fluorescent CsPb(Br,I) 3 perovskite quantum dots by surface modification with perfluorodecanoic acid

Iso Y., Eri M., Hiroyoshi R., Kano K., Isobe T.

Royal Society Open Science (Royal Society Open Science)  9 ( 8 )  2022.08

Joint Work,  ISSN  2054-5703

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CsPb(Br,I) 3 quantum dots (QDs) show application potential for optoelectronic devices. However, their thermal degradation is a significant problem. In this work, the effects of perfluorodecanoic acid (PFDA) modification on the photoluminescence (PL) and thermal resistance of CsPb(Br,I) 3 QDs were evaluated. The PL intensity of oleic-acid-modified quantum dots (OA-QDs) in toluene decreased drastically upon heating at 100°C. The PL quantum yield of the QDs increased from 69.6% to 77.4% upon modification with PFDA. Furthermore, the PL intensity of the QDs modified with PFDA (PFDA-QDs) increased to 140.6% upon heating, because of the reduction of surface defects upon adsorption of PFDA and its optimized adsorption state. A solid-film PFDA-QDs sample heated at 80°C for 4 h showed temporary PL enhancements for the OA-QDs and PFDA-QDs films to 445% and 557% of their initial values, respectively, upon heating for 0.25 h. This was attributed to the optimized adsorption states of the surface ligands. PFDA-QDs film maintained 354% after 4 h of heating, whereas that of OA-QDs film was 104%. Thus, PFDA modification enhances PL intensity and suppresses PL degradation under heating, which is important for wavelength converters for optoelectronic device applications.

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Bandgap-tuned fluorescent CuGaS<inf>2</inf>/ZnS core/shell quantum dots for photovoltaic applications

Hase S., Iso Y., Isobe T.

Journal of Materials Chemistry C (Journal of Materials Chemistry C)  10 ( 9 ) 3523 - 3530 2022.02

Joint Work,  ISSN  2050-7526

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This work investigated CuGaS2 (CGS)/ZnS quantum dots (QDs) as fluorescent materials for a luminescent downshifting (LDS) layer and a luminescent solar concentrator (LSC) with a single-crystalline silicon (sc-Si) solar module. The bandgap of the CGS/ZnS QDs was adjusted to ∼3.1 eV by changing the molar ratio of Cu/Ga, and in so doing a transparent and colorless LDS layer that converted near-ultraviolet (UV) light to visible light was fabricated. The resulting QDs, which exhibited a high photoluminescence quantum yield of 73%, were embedded in ethylene-vinyl acetate (EVA) copolymer resin to fabricate a QDs@EVA film. The short-circuit current (ISC) of the sc-Si solar module under simulated solar light decreased from 39.35 mA to 38.30 mA (−2.7%) by using the QDs@EVA film instead of an EVA film without QDs. Correspondingly, the photoelectronic conversion efficiency (η) changed from 18.07% to 17.56% (−2.8%). The decreased photocurrent was because of light scattering by aggregated QDs, and overcame the wavelength-conversion effect of the LDS film. In contrast, the QDs@EVA film was effective for LSC because the ISC and η relatively increased by +77.7% and +96.2%, respectively. The visible light emitted by the UV-excited QDs and the visible light scattered by the QDs contributed to the photoelectric conversion.

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Implications of gas-barrier properties in realizing the self-recovery of photodegraded CsPbBr<inf>3</inf>perovskite nanocrystals

Enomoto I., Iso Y., Isobe T.

Journal of Materials Chemistry C (Journal of Materials Chemistry C)  10 ( 1 ) 102 - 107 2022.01

Research paper (scientific journal), Joint Work, Accepted,  ISSN  20507534

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Fluorescent CsPbBr3perovskite nanocrystals (NCs) degraded by photoinduced desorption of surface ligands can exhibit self-recovery; however, irreversible oxidative damage from oxygen in the atmosphere must be avoided. In this work, gas-barrier polymer films made of ethylene vinyl alcohol (EVOH) and ethylene vinyl acetate (EVA) copolymers were investigated as sealing materials for CsPbBr3NC films. The NC film covered with EVOH showed photodegradation with blackening and photoluminescence quenching under light excitation, while self-recovery of the optical properties was observed during dark storage. These phenomena were attributed to the photoinduced desorption of surface ligands (and thus the formation of surface defects) and their re-adsorption, respectively. In contrast, self-recovery did not occur when an EVA film was used. X-ray photoelectron spectroscopy indicated the formation of Pb-O bonds for the EVA-coated film. Thus, EVOH, which has a lower oxygen permeability than EVA, successfully prevented irreversible damage by permeated oxygen. This is an important finding for the reuse or lifetime-extension of CsPbBr3NCs.

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Surface-Modified Carbon Dots with Improved Photoluminescence Quantum Yield for Color Conversion in White-Light-Emitting Diodes

Sato K., Katakami R., Iso Y., Isobe T.

ACS Applied Nano Materials (ACS Applied Nano Materials)  5 ( 6 ) 7664 - 7669 2022

Joint Work

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Surface modification of p-phenylenediamine-derived carbon dots using 4-morpholinoaniline with an electron-donating and rigid structure followed by purification using silica gel column chromatography increased the photoluminescence quantum yield from 28.3 to 41.8% in chloroform. The improved photoluminescence quantum yield was observed for the surface modification by postaddition of the surface modifier after the formation of the π-conjugated structure of the carbon dot core but was not observed for the carbon dots prepared from a mixture of p-phenylenediamine and 4-morpholinoaniline. The finding of this work gives us an idea to design carbon dots with high photoluminescence quantum yield for application of color conversion in white-light-emitting diodes.

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Transparent Nanocomposites Comprising Ligand-Exchanged CuInS<inf>2</inf>/ZnS Quantum Dots and UV-Cured Resin for Wavelength Converters

Shiraishi M., Iso Y., Isobe T.

ACS Omega (ACS Omega)  7 ( 37 ) 33039 - 33045 2022

Joint Work,  ISSN  2470-1343

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Quantum dots (QDs) dispersed in UV-curable resin are used for patterning in photolithography and inkjet printing. However, low affinity between the main component of UV-curable resins known as celloxide, an alicyclic diepoxy compound, and QD surface ligands with alkyl chains causes significant aggregation of QDs. In this study, the dispersibility of core/shell CuInS2/ZnS QDs with adsorbed 1-dodecanethiol and oleic acid in celloxide was improved using the ligand exchange method to prepare transparent fluorescent nanocomposites. Cyclohexyl 3-mercaptopropionate (MPACH) and 3-mercaptopropionic acid (MPA) were successfully adsorbed onto the QDs. MPACH-modified QDs (QD-MPACH) were well dispersed in the UV-curable resin, whereas MPA-modified QDs (QD-MPA) exhibited significant aggregation. Nanocomposite plates containing dispersed QDs were prepared by UV irradiation. The QD-MPACH nanocomposite plate was transparent, while the QD-MPA nanocomposite plate was turbid. The homogeneous dispersion of QD-MPACH was attributed to the similarity in the molecular structure between MPACH and celloxide. The photoluminescence (PL) peak of the QD-MPA nanocomposite occurred at a longer wavelength than that of the QD-MPACH nanocomposite. Furthermore, compared with the absolute photoluminescence quantum yield (PLQY) of the as-prepared QDs in toluene (55%), that of the QD-MPA nanocomposite was smaller (46%), and that of the QD-MPACH nanocomposite was higher (61%). An enhanced self-absorption effect was observed for the QD-MPA nanocomposite because of significant light scattering by the aggregates and concentration quenching, resulting in the PL redshift and decreased PLQY. Moreover, the PL intensity of the QD-MPACH nanocomposite was maintained at 98% of the initial value after continuous excitation-light irradiation for 5 h. The high PLQY and photostability of the QD-MPACH nanocomposite are beneficial in practical applications.

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Formation Process of Y<inf>2</inf>O<inf>3</inf>:Bi³⁺,Eu^{3 +}Nanosheets from Hydroxide Precursor Nanosheets

Matsunaga T., Iso Y., Isobe T.

ECS Journal of Solid State Science and Technology (ECS Journal of Solid State Science and Technology)  10 ( 9 ) 096013 2021.09

Research paper (scientific journal), Joint Work, Accepted,  ISSN  21628769

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We studied the formation of Y2O3:Bi3+,Eu3+ nanosheets from different Y2O3 precursors to propose a mechanism for their formation. One limitation of solar cells is their low sensitivity to near-ultraviolet light, which may be improved by including a phosphor to convert near-ultraviolet light to visible light, which can be readily absorbed. An attractive phosphor for this role is Y2O3:Bi3+,Eu3+; however, it remains unclear how Y2O3:Bi3+,Eu3+ forms from Y2O3 precursor nanosheets. Therefore, we studied the formation of Y2O3:Bi3+,Eu3+ nanosheets from Y2O3 precursors fabricated under various conditions including different pH, base type, and autoclave duration. We found that single-crystalline Y2O3:Bi3+,Eu3+ nanosheets formed from Y2O3 precursor nanosheets produced under suitable conditions. The Y2O3:Bi3+,Eu3+ nanosheets retained the crystallographic orientation of the precursor Y2O3 nanosheets. The formation of these nanosheets did not require the presence of organic ligands. Our findings indicate that Y2O3:Bi3+,Eu3+ nanosheet formation involved anisotropic assembly of crystallized nanoparticles and a subsequent dissolution-recrystallization process. The Y2O3:Bi3+,Eu3+ nanosheets fabricated under certain conditions displayed absorption and emission properties suitable for use as solar converters.

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Glycothermally Synthesized Carbon Dots with Narrow-Bandwidth and Color-Tunable Solvatochromic Fluorescence for Wide-Color-Gamut Displays

Yoshinaga T., Shinoda M., Iso Y., Isobe T., Ogura A., Takao K.I.

ACS Omega (ACS Omega)  6 ( 2 ) 1741 - 1750 2021.01

Research paper (scientific journal), Joint Work, Accepted,  ISSN  2470-1343

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© 2021 The Authors. Published by American Chemical Society. Fluorescent carbon dots (CDs) represent a promising eco-friendly next-generation phosphor. However, most CDs exhibit broad photoluminescence (PL) spectra [full width at half-maximum (fwhm) over 60 nm]; few works on CDs with sharp PL spectra (fwhm less than 40 nm) have been reported. In addition, their syntheses and color tuning require harsh conditions of high temperatures, long reaction times, and high pressures with catalysts. Here, we successfully prepared narrow-bandwidth emissive CDs (fwhm of 27-40 nm) from phloroglucinol in a glycol solvent of 1,2-pentanediol at temperatures as low as 180 °C for a reaction duration of as short as 6 h under ambient conditions without any catalysts via an open reaction system in which dehydration and condensation reactions among phloroglucinol molecules were enhanced. We shifted the emission peak from 463 to 511 nm by selecting seven kinds of solvents with different polarities, that is, emission colors could be tuned from blue to green by taking advantage of fluorescence solvatochromism. The CD-dispersed polymer films showed a similar solvatochromic behavior and sharp PL spectra, verifying the feasibility of applying the CDs to displays with a wide color gamut.

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Investigation on Photoluminescence of CsPb(Br,I)<inf>3</inf>Perovskite Nanocrystals by Comparison between Hot-Injection and Ion-Exchange Methods

Miyata S., Iso Y., Isobe T.

ECS Journal of Solid State Science and Technology (ECS Journal of Solid State Science and Technology)  10 ( 9 )  2021

Research paper (scientific journal), Joint Work, Accepted,  ISSN  21628769

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Changes in photoluminescence (PL) peak width and quantum yield (PLQY) with halide composition were compared for CsPb(Br1-x I x )3 nanocrystals (NCs) prepared by hot-injection and ion-exchange methods. The hot-injection method produced single-phase cubic CsPb(Br1-x I x )3 NCs for each iodide ratio. In contrast, a small amount of orthorhombic phase was observed at higher x for NCs prepared by the ion-exchange methods. The PL peak width of mixed-halide NCs at x = 0.55 was broader than those of CsPbBr3 and CsPbI3, possibly as a result of compositional inhomogeneity among the individual NCs. However, the maximum PL peak width occurred at larger x for the ion-exchange methods, possibly because of partial transition to orthorhombic phase from cubic phase for CsPb(Br1-x I x )3 NCs. The minimum PLQY for the hot-injection method was 25.0% at x = 0.50, which was lower than the PLQYs of CsPbBr3 and CsPbI3 NCs (∼70%). In contrast, the minimum PLQY for the ion-exchange methods occurred at x = ∼0.3. Furthermore, the minimum PLQY was ∼10%, which was lower than 25.0% for the hot-injection method. The addition of halide solution for ion exchange might affect the adsorption state of surface modifiers, leading to the decreased PLQY.

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Effects of Halide Composition on the Self-Recovery of Photodegraded Cesium Lead Halide Perovskite Nanocrystals: Implications for Photoluminescence Applications

Miyashita K., Kidokoro K., Iso Y., Isobe T.

ACS Applied Nano Materials (ACS Applied Nano Materials)  4 ( 11 ) 12600 - 12608 2021

Research paper (scientific journal), Joint Work, Accepted

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Photodegraded CsPbBr3 perovskite nanocrystals (NCs) can exhibit complete self-recovery following storage in the dark. This behavior results from the readsorption of surface ligands that experienced photoinduced desorption under UV light excitation. In the present work, mixed-halide CsPb(Cl0.4Br0.6)3, CsPb(Cl0.2Br0.8)3, and CsPb(Br0.7I0.3)3 NCs were prepared via ion exchange to evaluate the influence of halide composition on the photodegradation and self-recovery of NCs. Partially substituting Cl- for Br- enhanced the photoactivation, which improved the photoluminescence properties by optimizing the adsorption state of the surface ligands during light excitation. In contrast, partially substituting I- for Br- reduced the stability of the cubic crystal structure, thus subjecting the NCs to irreversible degradation (likely including a partial phase transition) and preventing their self-recovery. Cycle tests confirmed the reversibility of the photodegradation/self-recovery of CsPbBr3 NCs; however, this behavior was disturbed by irreversible surface oxidation reactions when the sample was exposed to ambient air. Therefore, it was concluded that ambient air must be excluded to effectively take advantage of the self-recovery phenomenon for practical applications.

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Feasibility of Emission-Enhanced CsPbCl<inf>3</inf>Quantum Dots Co-Doped with Mn²⁺and Er³⁺as Luminescent Downshifting Layers in Crystalline Silicon Solar Modules

Song P., Hase S., Zhao S., Xu Z., Iso Y., Isobe T.

ACS Applied Nano Materials (ACS Applied Nano Materials)  5 ( 2 ) 2522 - 2531 2021

Research paper (scientific journal), Joint Work, Accepted

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In order to enhance the photoelectric conversion efficiencies of crystalline silicon (c-Si) solar cells, CsPbCl3 quantum dots (QDs) codoped with Mn2+ and Er3+ (CsPbCl3:Mn2+, Er3+ QDs) were mixed with ethylene-(vinyl acetate) (EVA) to form a film which was used as a luminescent down-shifting (LDS) layer. The LDS layer effectively improved the low utilization of near-ultraviolet light of c-Si solar cells. These CsPbCl3:Mn2+,Er3+ QDs were synthesized via a conventional high-temperature injection method. Mn2+ is the luminescence center, and the incorporation of Er3+ greatly enhances the luminescence intensity of Mn2+. The absolute photoluminescence quantum yield of the QDs dispersed in toluene reached 79.5% when the QDs were synthesized under the optimum conditions, that is, an injection temperature of 180 °C and Pb:Mn:Er preparation molar ratios of 6:4:4. The EVA film embedded with QDs at the optimum concentration (0.9 wt %) was used as an LDS layer for c-Si solar module. The short-circuit current (ISC) and the photoelectric conversion efficiency (η) were increased by 3.42% and 4.02%, respectively, owing to the LDS layer. Moreover, a luminescent solar concentrator (LSC) which was another application of luminescent materials was also demonstrated. For LSC, the relative changes in ISC and η by using the QDs-dispersed EVA film were +14.9% and +18.0%, respectively. These results indicate a feasible application of luminescent downshifting films in solar modules.

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1. Particle characteristics and measurement 1.12 size effect of particle properties 1.12.1 nanophosphors: Fluorescent semiconductor quantum dots

Iso Y., Isobe T.

Journal of the Society of Powder Technology, Japan (Journal of the Society of Powder Technology, Japan)  57 ( 12 ) 641 - 6465 2020.12

Research paper (scientific journal), Joint Work, Accepted,  ISSN  03866157

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Photoluminescence properties of L-cysteine-derived carbon dots prepared in non-aqueous and aqueous solvents

Yoshinaga T., Akiu M., Iso Y., Isobe T.

Journal of Luminescence (Journal of Luminescence)  224 2020.08

Research paper (scientific journal), Joint Work, Accepted,  ISSN  00222313

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© 2020 Elsevier B.V. Fluorescent carbon dots (CDs) can be produced from amino acids such as L-cysteine by an intermolecular dehydration reaction between NH2 and COOH groups, followed by carbonization. This dehydration reaction may be hindered in aqueous media because the amino acid molecules are surrounded by water; therefore, we used a non-aqueous reaction media to facilitate the dehydration reaction. In the present study, L-cysteine was heated at 230 °C for 30 min in a non-aqueous solvent, diphenyl ether, which has a high boiling point of 258 °C, to yield CDs-NA. For comparison, we also hydrothermally prepared CDs-A from L-cysteine dissolved in water, with the use of an autoclave and microwave heating system under the same temperature and time conditions. The maximum photoluminescence (PL) intensity of the water dispersion of CDs-NA was 1.5 times as high as that of the CDs-A. The absolute PL quantum yield (QY) of CDs-NA was 4.2%, which was 1.4 times as high as that of CDs-A, 3.0%. Characterization of the elemental compositions, particulate properties, and chemical bonding states confirmed that the non-aqueous solvent not only facilitated CD formation via the dehydration reaction but also contributed to the formation of sulfonic acid groups by oxidation of thiol groups. The rapid particle growth and formation of the additional functional groups might contribute to the increased PL intensity and absolute PLQY of CDs-NA. Through the optimization of the synthesis conditions in a non-aqueous solvent, the absolute PLQY of CDs-NA was increased from 4.2% to 10.2%.

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Bandgap-Tuned CuInS<inf>2</inf>/ZnS Core/Shell Quantum Dots for a Luminescent Downshifting Layer in a Crystalline Silicon Solar Module

Nakamura Y., Iso Y., Isobe T.

ACS Applied Nano Materials (ACS Applied Nano Materials)  3 ( 4 ) 3417 - 3426 2020.04

Research paper (scientific journal), Joint Work, Accepted

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Copyright © 2020 American Chemical Society. CuInS2 (CIS) quantum dots (QDs) were investigated as a luminescent downshifting (LDS) material that converts near-ultraviolet (UV) light to visible light and were applied to a single crystalline silicon (c-Si) solar module that has no spectral sensitivity in the near-UV region. The bandgap of the CIS/ZnS core/shell QDs was successfully adjusted to &tild;3 eV, which was adequate for the LDS layer in solar devices, by changing the molar ratio of Cu/In. CIS/ZnS/ZnS core/shell/shell QDs with 59.9% absolute photoluminescence (PL) quantum yield were prepared by the hot-injection method and embedded in ethylene-vinyl acetate copolymer (EVA) resin to fabricate QD@EVA films as the LDS layer. The PL intensity of the QD@EVA films under near-UV excitation monotonically increased with increasing QD concentration. The films were attached to a commercial single c-Si solar module. The advantages and drawbacks of the films were discussed based on the results of incident photon-to-electron conversion efficiency and current-voltage curve measurements.

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Surface modification strategy for fluorescence solvatochromism of carbon dots prepared from: P -phenylenediamine

Sato K., Sato R., Iso Y., Isobe T.

Chemical Communications (Chemical Communications)  56 ( 14 ) 2174 - 2177 2020.02

Research paper (scientific journal), Joint Work, Accepted,  ISSN  13597345

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This journal is © The Royal Society of Chemistry. The fluorescence solvatochromism of p-phenylenediamine-derived carbon dots (CDs) was modulated through surface modification with decanoic acid or perfluorodecanoic acid. This is attributed to the adjustment of the dipole interaction between solvent molecules and the CD surface in terms of steric hindrance of a surface modifier and polarization of the modified CD surface.

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Critical Review - Photostable Fluorescent Cd-Free Quantum Dots Transparently Embedded in Monolithic Silica

Iso Y., Isobe T.

ECS Journal of Solid State Science and Technology (ECS Journal of Solid State Science and Technology)  9 ( 1 )  2020

Research paper (scientific journal), Joint Work, Accepted,  ISSN  21628769

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© The Author(s) 2019. Published by ECS.. Fluorescent Cd-free quantum dots (QDs) such as InP/ZnS and CuInS2/ZnS have attracted attention for use as color converters for blue light emitting diodes. To protect QDs from oxygen, which degrades them by photo-oxidation during excitation, we fabricated a transparent monolithic silica composite containing the QDs using an aqueous solution of tetramethylammonium silicate (TMAS) as a silica source. The TMAS solution readily dispersed the negatively charged QDs prepared by ligand exchange of 1-dodecanethiol for 3-mercatopropionic acid (MPA). A highly transparent monolithic TMAS-derived silica composite containing the MPA-capped QDs was obtained from the QD dispersion through a sol-gel process. Improved photostability of QDs was explained by the TMAS-derived silica acting as a gas barrier to protect the embedded QDs from photo-oxidation by oxygen in air.

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Effective Stabilization of Perovskite Cesium Lead Bromide Nanocrystals through Facile Surface Modification by Perfluorocarbon Acid

Sato D., Iso Y., Isobe T.

ACS Omega (ACS Omega)  5 ( 2 ) 1178 - 1187 2020

Research paper (scientific journal), Joint Work, Accepted

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© 2020 American Chemical Society. CsPbX3 (X = Cl, Br, I) perovskite nanocrystals (NCs) have attracted much attention as promising materials for next-generation optoelectronic applications. However, improvement of their low stabilities against heating and humidity is needed for practical use. In this work, we focused on perfluorodecanoic acid (PFDA) as a surface ligand and investigated the thermal and chemical stabilities of the photoluminescence (PL) properties of CsPbBr3 NCs. Oleic acid (OA) adsorbed on the NCs was exchanged for decanoic acid (DA) and PFDA. OA-modified and DA-modified NCs exhibited drastic fluorescence quenching to 12.9 and 21.1% of their initial PL intensities, respectively, after heating at 100 °C for 4 h. In contrast, the PFDA-modified NCs maintained 92.1% of their PL intensity after the same heating. Furthermore, the polar solvent resistance was also improved by PFDA modification. These improvements can be attributed to the strong adsorptivity and high chemical stability of the PFDA ligand.

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Musa AAA and Jatropha curcas L. sap mediated TiO<inf>2</inf> nanoparticles: Synthesis and characterization

Wagutu A., Yano K., Sato K., Park E., Iso Y., Isobe T.

Scientific African (Scientific African)  6 2019.11

Research paper (scientific journal), Joint Work, Accepted

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© 2019 Titanium dioxide (TiO2) nanoparticles were synthesized using East African highland banana (Musa AAA) and Jatropha curcas L. sap. The nanoparticles were characterized with X-ray diffractometry (XRD), Raman spectroscopy, Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). FT-IR peaks show presence of amino, carboxyl and hydroxyl groups on the crystal surface of the nanoparticles. XRD and Raman characteristic indicate anatase phases. The average crystallite size calculated from XRD peak width using Scherrer equation are 5.5 nm and 6.1 nm for Jatropha and Musa AAA sap TiO2 particles respectively. SEM images show polydispersed spherical clusters of agglomerated nanoparticles. The nanoparticles showed antimicrobial activity against gram-negative bacteria when irradiated in natural sunlight for 2 h. The sap extracts provide a simple, cheaper and more environmentally benign reducing and stabilizing agents for transforming transition metal salts into nano-scale particles, which have wide range of industrial applications.

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Optimizing the microwave-assisted hydrothermal synthesis of blue-emitting L-cysteine-derived carbon dots

Yoshinaga T., Iso Y., Isobe T.

Journal of Luminescence (Journal of Luminescence)  213   6 - 14 2019.09

Research paper (scientific journal), Joint Work, Accepted,  ISSN  00222313

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© 2019 Elsevier B.V. We synthesized carbon dots (CDs)from biocompatible L-cysteine, containing N and S, through an eco-friendly, facile hydrothermal reaction. These L-cysteine-derived CDs are produced by pyrolysis and carbonization after dehydration between NH 2 and COOH groups of L-cysteine. To optimize the microwave-assisted hydrothermal synthesis of the blue-emitting L-cysteine-derived CDs, we varied the hydrothermal temperature, hydrothermal duration, synthesis pH, and L-cysteine concentration. We synthesized CDs from 17 to 133 mmol L −1 aqueous solutions of L-cysteine whose pH values were 1, 7, or 13 through hydrothermal treatment at 110–230 °C for 5–120 min using a microwave heater. The absorbance of transitions related to C[dbnd]C, C[dbnd]O, and C[dbnd]N bonds increased through hydrothermal treatment at increasing temperature and for increasing duration. At the same time, the photoluminescence (PL)intensity and PL quantum yield (QY)of blue emission from the CDs under near-UV excitation increased. We propose that higher temperature and longer duration promote the carbonization, oxidation, and doping of nitrogen into CDs, resulting in the formation of π levels, surface state levels related to functional groups, and N-doped levels, respectively. The absorbance and PL intensity of the CDs prepared at pH 7 were the highest among the pH values 1, 7, and 13. The protonation of NH 2 groups at pH 1 and the deprotonation of COOH groups at pH 13 suppressed dehydration between the NH 2 and COOH groups of L-cysteine. In contrast, rapid dehydration at pH 7 induced carbonization, contributing to the maximized absorbance and PL intensity. The absorbance, PL intensity, and PL QY increased through hydrothermal treatment at increasing L-cysteine concentration. Higher L-cysteine concentration promoted dehydration between molecules and the subsequent carbonization, improving the optical properties.

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Electrophoretically Deposited Y<inf>2</inf>O<inf>3</inf>:Bi³⁺,Yb³⁺ Nanosheet Films as Spectral Converters for Crystalline Silicon Solar Devices

Watanabe R., Iso Y., Isobe T.

ACS Applied Nano Materials (ACS Applied Nano Materials)  2 ( 6 ) 4009 - 4017 2019.06

Research paper (scientific journal), Joint Work, Accepted

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© 2019 American Chemical Society. Transparent Y2O3:Bi3+,Yb3+ films that exhibit near-infrared (NIR) emission under near-ultraviolet (NUV) excitation are candidates for the spectral converters in crystalline silicon solar devices. In this work, NIR-emitting films were fabricated by the aqueous electrophoretic deposition of Y2O3:Bi3+,Yb3+ nanosheets, and their photoluminescence (PL) properties were enhanced by a postcalcination process. Positively charged Y2O3:Bi3+,Yb3+ nanosheets with adsorbed polyethylenimine (PEI) were deposited as a uniform and dense micrometer thick layer on a transparent conductive substrate by applying an electric field to an aqueous nanosheet dispersion. The resulting nanosheet film showed NIR emission from Yb3+, realized through energy transfer from Bi3+, when excited under NUV light. The NIR PL intensity of the film was improved by calcination at 700-1000 °C under a flow of air. This NIR PL enhancement was explained by the calcination process increasing the crystallinity of the Y2O3:Bi3+,Yb3+ nanosheets and removing adsorbed hydroxyl groups that quenched the NIR emission of Yb3+. Furthermore, the increased energy transfer efficiency of the Bi3+ → Yb3+ transition with increasing calcination temperature also contributed to the observed NIR PL enhancement of the nanosheet film. The NIR PL intensity of the as-deposited nanosheet film did not change under continuous NUV excitation, whereas a gradual increase in the PL intensity was observed for the calcined nanosheet films. This increase in the PL intensity of the calcined films would be caused by the photooxidation of the Bi and Yb ions, which were partially reduced by PEI during the calcination process.

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Complete self-recovery of photoluminescence of photodegraded cesium lead bromide quantum dots

Kidokoro K., Iso Y., Isobe T.

Journal of Materials Chemistry C (Journal of Materials Chemistry C)  7 ( 28 ) 8546 - 8550 2019

Research paper (scientific journal), Joint Work, Accepted,  ISSN  20507534

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© The Royal Society of Chemistry 2019. CsPbBr3 quantum dots were packed in a cell and irradiated at 468 nm. The sample color changed to black, attributed to the formation of surface defects by photoinduced desorption of surface ligands. The color and photoluminescence properties completely recovered during subsequent dark storage. This can be explained by readsorption of the surface ligands.

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Effects of oleic acid on the stability of perovskite CsPbBr <inf>3</inf> quantum dot dispersions

Kosugi T., Iso Y., Isobe T.

Chemistry Letters (Chemistry Letters)  48 ( 4 ) 349 - 352 2019

Research paper (scientific journal), Joint Work, Accepted,  ISSN  03667022

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© 2019 The Chemical Society of Japan. We investigated the effects of addition of oleic acid (OA) on the stability of CsPbBr 3 quantum dot (QD) dispersions in toluene during storage and light irradiation. Excess amounts of OA degraded the fluorescent perovskite CsPbBr 3 QDs because of promoted crystal growth through dissolution and reprecipitation. In contrast, a suitable amount of OA (0.2 vol%) improved their photostability possibly due to re-adsorption of OA on the exposed CsPbBr 3 crystal surface after the photoinduced desorption of OA.

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Green Photoluminescence of Perovskite CsPb(Br<inf>1- x</inf>I<inf>x</inf>)<inf>3</inf> Nanocrystals for Wide Color Gamut Displays

Miyata S., Iso Y., Isobe T.

ACS Omega (ACS Omega)  4 ( 12 ) 15067 - 15073 2019

Research paper (scientific journal), Joint Work, Accepted

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© 2019 American Chemical Society. All-inorganic mixed-halide CsPb(Br1-xIx)3 perovskite nanocrystals (NCs) are excellent candidates for green-emitting phosphors in wide color gamut displays; however, a detailed investigation of their photoluminescence (PL) properties based on the halide composition has been missing. In this work, we report a fundamental investigation of the changes in the PL properties of CsPb(Br1-xIx)3 NCs. The PL color of the NCs, which were prepared by a hot-injection method, changed from green to red with increasing iodide composition (x). Almost ideal green emission close to the chromaticity coordinates of the green vertex of the BT.2020 standard was achieved by appropriately substituting iodide ions for bromide ions in monohalide CsPbBr3 NCs. However, the PL peak width of the mix-halide NCs at x ∼0.5 was 0.127 eV, which was broader than the 0.105 eV peak width of the monohalide CsPbBr3 NCs. This phenomenon should be due to the compositional inhomogeneity among the individual CsPb(Br1-xIx)3 NCs. On the other hand, the PL quantum yield (PLQY) for the monohalide CsPbBr3 NCs decreased from 70 to 25% as x increased to 0.5. This result may be attributed to lattice distortion by the difference in the ionic radii of bromide and iodide. Improvements in the compositional inhomogeneity and lattice distortion would enhance the color purity of the green emission and the PLQY, respectively, of the CsPb(Br1-xIx)3 NCs.

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Fluorescence Solvatochromism of Carbon Dot Dispersions Prepared from Phenylenediamine and Optimization of Red Emission

Sato R., Iso Y., Isobe T.

Langmuir (Langmuir)   2019

Research paper (scientific journal), Joint Work, Accepted,  ISSN  07437463

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© 2019 American Chemical Society. Fluorescent carbon dots (CDs) are of interest as a promising alternative to quantum dots, partly because they do not include heavy metals. However, most CDs exhibit blue or green emission, while red-emitting CDs are required for a variety of applications. In the present work, CDs were synthesized by refluxing three phenylenediamine (PD) isomers with amino groups at different positions (o-PD, m-PD, and p-PD) in diphenyl ether at 250 °C for 4 h. Upon dispersing the resulting CDs in eight solvents with different polarities, emission colors ranging from green to red were observed. Among these CDs, p-PD-derived CDs exhibited both the longest emission wavelength range, from 538 to 635 nm, and the highest absolute red photoluminescence quantum yield (PLQY) of 15%. Herein the results are discussed based on a comparison of the polymerization processes of o-PD, m-PD, and p-PD. This work demonstrated that the optimum reaction time was 2 h, which yields a p-PD-derived CD dispersion in methanol with red emission and an absolute PLQY as high as 18%. Additionally, the use of 1-decanol and deuterated methanol in place of methanol improved the maximum absolute PLQY to 25% and 36%, respectively. These improved values are attributed to reduced concentration quenching by suppression of Ï€-πstacking interactions and inhibition of the nonradiative relaxation process through the vibration of OH groups, respectively.

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Ligand exchange of core/shell CuInS2/ZnS quantum dots for preparation of their homogeneous ink

Shiraishi M., Iso Y., Isobe T., Seshimo T., Liao Y.C., Noda K., Shiota D.

Proceedings of the International Display Workshops (Proceedings of the International Display Workshops)  2   803 - 805 2019

Research paper (scientific journal), Joint Work, Accepted

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1-Dodecanethiol on CuInS2/ZnS quantum dots (QDs) was exchanged with cyclohexanethiol. The obtained QDs were transparently dispersed in alicyclic diepoxy compound to yield the QD ink for ink-jet printing. This homogeneous dispersion is attributed to similarity in molecular structure between the ligand and the ink component.

Preparation and characterization of Y<inf>2</inf>O<inf>3</inf>:Bi³⁺,Yb³⁺ nanosheets with wavelength conversion from near-ultraviolet to near-infrared

Fujita K., Watanabe R., Iso Y., Isobe T.

Journal of Luminescence (Journal of Luminescence)  198   243 - 250 2018.06

Research paper (scientific journal), Joint Work, Accepted,  ISSN  00222313

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© 2018 Elsevier B.V. Y2O3:Bi3+,Yb3+ nanophosphors, which exhibit near-infrared (NIR) emission under near-ultraviolet (near-UV) excitation, are promising candidates for spectral converters in crystalline silicon solar devices. Herein, Y2O3:Bi3+,Yb3+ nanosheets were prepared by calcination of hydrothermally-synthesized precursors. The effects of the calcination temperature on their properties were investigated. The nanosheets calcined at ≤ 800 °C had sheet-like, square morphologies with average lateral sizes of 210–240 nm, which were smaller than precursor nanosheet with 257 nm attributed to shrinkage through the calcination. The thickness of the nanosheet before and after calcination at 800 °C was ~20 nm. Moreover, the nanosheet had a single-crystal nature. However, at calcination temperatures ≥ 900 °C, the nanosheets lost their morphologies, and transformed into irregular particles. The Y2O3:Bi3+,Yb3+ nanosheets showed visible emission from Bi3+ and NIR emission from Yb3+ under near-UV excitation. The PL intensity and PL decay time of the NIR emission monotonically increased with increasing calcination temperature. Both increases can be explained by the following effects: (i) removal of H2O molecules adsorbed on the nanosheet surface, (ii) improvement of crystallinity and decrease of specific surface area, (iii) increase in probability of energy transfer from Bi3+ to Yb3+, and (iv) oxidation of reduced bismuth during calcination. Furthermore, the photostability of the nanosheets under near-UV excitation was improved by increasing calcination temperature.

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Electrophoretically Deposited Y<inf>2</inf>O<inf>3</inf>:Bi³⁺,Eu³⁺ Nanosheet Films with High Transparency for Near-Ultraviolet to Red Light Conversion

Kosuge Y., Iso Y., Isobe T.

Langmuir (Langmuir)  34 ( 13 ) 3813 - 3820 2018.04

Research paper (scientific journal), Joint Work, Accepted,  ISSN  07437463

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© 2018 American Chemical Society. Fluorescent films were fabricated by depositing Y2O3:Bi3+,Eu3+ nanosheets, which emit red light under near-UV irradiation. The Y2O3:Bi3+,Eu3+ nanosheets were obtained by calcining hydroxide precursor nanosheets synthesized through a hydrothermal method. An aqueous dispersion of positively charged Y2O3:Bi3+,Eu3+ nanosheets with polyethyleneimine adsorbed to the surface was prepared for their deposition. Fluorescent nanosheets were electrophoretically deposited on a transparent conductive substrate under a constant voltage. The obtained nanosheet films were dense and uniform and showed excellent photostability against the excitation light. Growth of the nanosheet film caused a decrease in transmittance and an increase in the photoluminescence intensity. The former effect was attributed to light scattering from inner voids and the rough surface of the film. A polyvinylpyrrolidone (PVP) coating on the film improved the transmittance to be greater than 70% over the visible region. These effects were attributed to antireflection effects at the film surface owing to the low refractive index of PVP. Furthermore, suppression of light scattering by coating the rough surface with a smooth PVP film and filling of voids in the nanosheet film with PVP also improved the transmittance.

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Fluorescent Ag⁺-exchanged zeolite nanoparticles with improved photoluminescence properties via X-ray irradiation

Taiji K., Iso Y., Isobe T.

Journal of Luminescence (Journal of Luminescence)  196   214 - 220 2018.04

Research paper (scientific journal), Joint Work, Accepted,  ISSN  00222313

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© 2017 Elsevier B.V. Fluorescent Faujasite (FAU)-Y Ag+-exchanged zeolite is a lanthanide-free phosphor with a high photoluminescence (PL) quantum yield to convert near-ultraviolet (near-UV) to visible light. Here, we focused on nanometer-sized fluorescent FAU Ag+-exchanged zeolite as a wavelength converter for optoelectronic devices. The prepared Ag+-exchanged zeolite nanoparticles were irradiated with X-rays to improve their PL properties because X-ray irradiation does not possess the disadvantages of other treatments, such as aggregation and sintering of nanoparticles exposed to thermal treatment, excessive growth of silver particles with visible light absorption following chemical reduction, and amorphization of zeolite by high-energy electron beam irradiation. FAU-Y zeolite nanoparticles were prepared by template-free hydrothermal synthesis and then fluorescent Ag+-exchanged zeolite nanoparticles were obtained through the ion exchange of Na+ with Ag+. The prepared Ag+-exchanged zeolite nanoparticles were irradiated by X-rays from a commercial tabletop device. The average size of the as-prepared zeolite nanoparticles was 35.7 ± 12.6 nm according to transmission electron microscopy (TEM) images. TEM also confirmed that Ag-related particles such as silver clusters and/or silver nanoparticles were generated and grew from Ag+, possibly through reduction accompanied with oxidation of oxide ions of the zeolite framework during X-ray irradiation. PL quantum efficiency was enhanced by X-ray irradiation by up to ~3 times. Analysis of PL properties and electron spin resonance spectra implied that fluorescent Ag42+ clusters were formed under X-ray irradiation, resulting in the enhancement of PL quantum efficiencies. Similar behavior was also observed for micrometer-sized Ag+-exchanged zeolites. X-ray irradiation of fluorescent Ag+-exchanged zeolites is therefore a useful method to improve their PL properties.

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Particulate, Structural, and Optical Properties of D-Glucose-Derived Carbon Dots Synthesized by Microwave-Assisted Hydrothermal Treatment

Taishu Yoshinaga, Yoshiki Iso, Tetsuhiko Isobe

ECS J. Solid State Sci. Technol. (ECS Journal of Solid State Science and Technology)  7 ( 1 ) R3034 - R3039 2018.01

Research paper (scientific journal), Joint Work, Accepted,  ISSN  21628769

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© The Author(s) 2017. Published by ECS. Environmentally friendly and visible fluorescent carbon dots (CDs) have received attention as alternatives to compound semiconductor quantum dots containing toxic elements. Hydrothermal reaction of water-soluble carbohydrates can provide an eco-friendly and facile synthesis approach to CDs. In this study, we have attempted to efficiently produce uniform CDs using a microwave heating system that can maintain the reaction solution at a constant temperature.We synthesized CDs from D-glucose through hydrothermal treatment at 200°C for 5-60 min. From transmission electron microscopy, the particle size of the CDs increased in proportion to the hydrothermal duration. Furthermore, the absorbance and maximum photoluminescence intensity of the CDs aqueous dispersions (10 mg L-1) increased with an increase in hydrothermal duration. The maximum photoluminescence intensity of the dispersions decreased at pH < 4 and pH > 10; the absorbance at the excitation wavelength remained unchanged. These results indicate that the number of emission sites and absorption sites increased with an increase in the particle size and that emission sites were located near the surface of the obtained CDs.

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Review-synthesis, luminescent properties, and stabilities of cesium lead halide perovskite nanocrystals

Iso Y., Isobe T.

ECS Journal of Solid State Science and Technology (ECS Journal of Solid State Science and Technology)  7 ( 1 ) R3040 - R3045 2018

Research paper (scientific journal), Joint Work, Accepted,  ISSN  21628769

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© The Author(s) 2017. Published by ECS. All-inorganic cesium lead halide perovskite CsPbX3(X = Cl, Br, I) nanocrystals have emerged as promising luminescent quantum dots. In this review, we summarize recent work on their synthesis, luminescent properties, and stabilities. Through controlling the composition of the alloyed halides and quantum size effects, the band gaps and emission wavelengths of CsPbX3nanocrystals are readily tunable over the entire visible range. Their sharp emission line-widths extend the color gamut of liquid crystal displays. They also exhibit high photoluminescence (PL) quantum yields and fast PL lifetimes. CsPbX3nanocrystals with both cubic and plate shapes have been successfully synthesized through several liquid-phase methods, such as hot-injection, room-temperature, and amine-free methods. The sizes and shapes of CsPbX3nanocrystals can be controlled via the reaction temperature and the length of the n-alkyl carboxylic acids and n-alkylamines used in their synthesis. Several attempts have been made to improve their stabilities during storage, at high temperature, and under light irradiation, for example by incorporation of CsPbX3nanocrystals into silica or polymer matrixes.

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Photoluminescence color stability of green-emitting InP/ZnS core/shell quantum dots embedded in silica prepared via hydrophobic routes

Watanabe T., Iso Y., Isobe T., Sasaki H.

RSC Advances (RSC Advances)  8 ( 45 ) 25526 - 25533 2018

Research paper (scientific journal), Joint Work, Accepted

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© The Royal Society of Chemistry 2018. In this work, green-emitting InP/ZnS quantum dots (QDs) modified with 1-dodecanethiol were embedded into silica by two methods to improve their photostability while maintaining a high photoluminescence quantum yield (PLQY) and a color coordinate. A monolithic QD-silica composite prepared by a non-aqueous route with tetraethyl orthosilicate and lactic acid featured low transparency, a loss of the color purity of green, and a PLQY of 1.6%, which was considerably lower than that of the original QDs (67%). The decrease of the PLQY was attributed to QD aggregation in the sol-gel process and degradation of the QDs by the acid. The alternative method involved stirring a toluene dispersion of the QDs with tetramethyl orthosilicate (TMOS) for 20 h or 7 days. The PLQY of the TMOS-modified InP/ZnS QDs (20 h) was 62%, which was only slightly lower than that of the original QDs. The PLQY decreased to 52% when the duration of aging was prolonged to 7 days. This decrease was attributed to desorption of surface modifiers from the QD surface and oxidative degradation by oxygen dissolved in toluene. Herein, the color coordinate was maintained stably. Photostability was evaluated by continuous irradiation of the samples by a blue light emitting diode. The decrease of photoluminescence (PL) intensity was suppressed by the silica encapsulation. In particular, the PL intensity of the TMOS-modified InP/ZnS QD sample (7 d) maintained 99% of its initial intensity. Silica encapsulation of InP/ZnS QDs prevented contact of the QDs with oxygen in the air, resulting in improved photostability.

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Improved Photostability of Tetramethyl Orthosilicate-Modified InP/ZnS Quantum Dots

Taichi Watanabe, Yoshiki Iso, Tetsuhiko Isobe, Hirokazu Sasaki

Proceedings of the 24th International Display Workshops    671 - 672 2017.12

Research paper (international conference proceedings), Joint Work

Preparation of Photostable Fluorescent InP/ZnS Quantum Dots Embedded in TMAS-Derived Silica

Taichi Watanabe, Chikako Wada, Yoshiki Iso, Tetsuhiko Isobe, Hirokazu Sasaki

ECS J. Solid State Sci. Technol. 6 ( 7 ) R75 - R80 2017.05

Research paper (scientific journal), Joint Work, Accepted

Combinatorial optimization of the atomic compositions for green-emitting YBO3:Ce3+,Tb3+ and red-emitting YBO3:Ce3+,Tb3+,Eu3+ phosphors using a microplate reader

Kohei Yano, Satoru Takeshita, Yoshiki Iso, Tetsuhiko Isobe

RSC Adv. 7   17586 - 17592 2017.03

Research paper (scientific journal), Joint Work, Accepted

Synthesis of Y2O3:Bi3+,Eu3+ nanosheets from layered yttrium hydroxide precursor and their photoluminescence properties

Tomotaka Watanabe, Yoshiki Iso, Tetsuhiko Isobe

RSC Adv. 7   14107 - 14113 2017.03

Research paper (scientific journal), Joint Work, Accepted

Preparation and photoluminescence properties of yellow-emitting CuInS2/ZnS quantum dots embedded in TMAS-derived silica

Chikako Wada, Yoshiki Iso, Tetsuhiko Isobe, Hirokazu Sasaki

RSC Adv. 7   7936 - 7943 2017.01

Research paper (scientific journal), Joint Work, Accepted

Synthesis of Y2O3:Bi3+,Yb3+ nanosheets from layered yttrium hydroxide precursor and their photoluminescence properties

Keita Higashi, Yutaka Watanabe, Yoshiki Iso, Tetsuhiko Isobe

RSC Adv. 7   6671 - 6678 2017.01

Research paper (scientific journal), Joint Work, Accepted

Influence of chemical states of doped nitrogen on photoluminescence intensity of hydrothermally synthesized carbon dots

Shinichiro Niino, Satoru Takeshita, Yoshiki Iso, Tetsuhiko Isobe

J. Lumin. 180   123 - 131 2016.12

Research paper (scientific journal), Joint Work, Accepted

Low-temperature synthesis of YVO4:Bi3+,Eu3+ nanoparticle phosphors using a methanol solution of trivalent cations

Takayuki Ohno, Yoshiki Iso, Tetsuhiko Isobe

ECS J. Solid State Sci. Technol. 5 ( 9 ) R142 - R145 2016.09

Research paper (scientific journal), Joint Work, Accepted

Photoluminescence and photostability of YVO4:Eu3+ nanoparticle/layered double hydroxide multilayer films prepared via layer-by-layer assembly

Wataru Onishi, Satoru Takeshita, Yoshiki Iso, Tetsuhiko Isobe

J. Lumin. 175   71 - 77 2016.07

Research paper (scientific journal), Joint Work, Accepted

Solvothermal synthesis of YBO3:Ce3+,Tb3+ nanophosphor: influence of B/(Y + Ce + Tb) ratio on particle size and photoluminescence intensity

Akihiro Nohara, Satoru Takeshita, Yoshiki Iso, Tetsuhiko Isobe

J. Mater. Sci. 51 ( 7 ) 3311 - 3317 2016.04

Research paper (scientific journal), Joint Work, Accepted

Preparation, Photoluminescence, and Photostability of Transparent Composite Films of Glycothermally Synthesized YAG:Ce3+ Nanoparticles for White LED

Yuta Sasaki, Satoru Takeshita, Tetsuhiko Isobe

ECS J. Solid State Sci. Technol. 5 ( 1 ) R3049 - R3054 2016.01

Research paper (scientific journal), Joint Work, Accepted

Synthesis, photoluminescence, and photostability of Y2O3:Bi3+,Eu3+ nanosheets

Takuya Matsunaga, Satoru Takeshita, Tetsuhiko Isobe

J. Lumin. 165   62 - 67 2015.09

Research paper (scientific journal), Joint Work, Accepted

Two Photoenergy Conversion Modes of YVO4:Eu3+ Nanoparticles: Photoluminescence and Photocatalytic Activity

Yusuke Shiraishi, Satoru Takeshita, Tetsuhiko Isobe

J. Phys. Chem. C 119   13502 - 13508 2015.06

Research paper (scientific journal), Joint Work, Accepted

太陽電池応用に向けた波長変換材料の研究動向

磯部 徹彦

セラミックス 50 ( 3 ) 197-200 2015.03

Research paper (scientific journal), Single Work

Composites of Eu3+-doped calcium apatite nanoparticles and silica particles: comparative study of two preparation methods

Ayumu Isobe, Satoru Takeshita, Tetsuhiko Isobe

Langmuir 31   1811 - 1819 2015.01

Research paper (scientific journal), Joint Work, Accepted

Formation of Cu2SnS3 nanoparticles by sequential injection of tin and sulfur oleylamine solutions into Cu1.8S nanoparticle dispersion

Shin Okano, Satoru Takeshita, Tetsuhiko Isobe

Mater. Lett. 145   79 - 82 2015.01

Research paper (scientific journal), Joint Work, Accepted

ナノ蛍光材料の特性・作製方法と波長変換機能を用いた応用

磯部 徹彦

光アライアンス 25 ( 10 ) 9-12 2014.10

Research paper (scientific journal), Single Work

Effects of Annealing on the Photoluminescence Properties of Citrate-Capped YVO4:Bi3+,Eu3+ Nanophosphor

Yoshiki Iso, Satoru Takeshita, Tetsuhiko Isobe

J. Phys. Chem. C 118   11006 - 11013 2014.05

Research paper (scientific journal), Joint Work, Accepted

Mixed-solvent strategy for solvothermal synthesis of well-dispersed YBO3:Ce3+,Tb3+ nanocrystals

A. Nohara, S. Takeshita, T. Isobe

RSC Adv. 4   11219-11224 2014.02

Research paper (scientific journal), Joint Work, Accepted

Effects of post heat treatment on near infrared photoluminescence of YAG:Yb3+ nanoparticles synthesized by glycothermal method

R. Asakura, T. Isobe

J. Lumin. 146   492-496 2014.02

Research paper (scientific journal), Joint Work, Accepted

Fabrication and Characterization of Transparent Monolithic Nanocomposites between YVO4:Bi3+,Eu3+ Nanophosphor and TMAS-Derived Silica

Y. Iso, S. Takeshita, T. Isobe

Opt. Mater. 36   717-722 2014.02

Research paper (scientific journal), Joint Work, Accepted

Electrophoretic Deposition and Characterization of Transparent Nanocomposite Films of YVO4:Bi3+,Eu3+ Nanophosphor and Silicone-Modified Acrylic Resin

Y. Iso, S. Takeshita, T. Isobe

Langmuir 30   1465-1471 2014.02

Research paper (scientific journal), Joint Work, Accepted

An anomalous downsizing of glycothermally-synthesized YBO3 crystals by Ce3+ doping

A. Tani, H. Hara, S. Takeshita, T. Isobe

CrystEngComm 15   10059-10067 2013.11

Research paper (scientific journal), Joint Work, Accepted

Surface modification of YAG:Ce3+ nanoparticles by poly(acrylic acid) and their biological application

R. Asakura, T. Isobe

J. Mater. Sci. 48   8228-8234 2013.08

Research paper (scientific journal), Joint Work, Accepted

Relation between shell thickness and near infrared photoluminescence of LaPO4:Yb3+/GdPO4 core/shell nanoparticles

T. Shimizu, T. Isobe

Mater. Lett. 110   180-183 2013.08

Research paper (scientific journal), Joint Work, Accepted

Polyol synthesis of YVO4:Bi3+,Eu3+ nanophosphors and effect of silica coating on their photoluminescence properties

H. Hara, S. Takeshita, T. Isobe, T. Sawayama,S. Niikura

J. Ceram. Process. Res. 14   s18-s21 2013.06

Research paper (scientific journal), Joint Work, Accepted

Glycothermal synthesis and photoluminescent properties of Ce3+-doped YBO3 mesocrystals

H. Hara, S. Takeshita, T. Isobe, Y. Nanai, T. Okuno, T. Sawayama,S. Niikura

J. Alloys Compd. 577   320-326 2013.06

Research paper (scientific journal), Joint Work, Accepted

Glycothermally Synthesized YAG:Ce3+ Nanophosphors for Blue LEDs

T. Isobe

ECS J. Solid State Sci. Technol. 2 ( 2 ) R3012-R3017 2013.02

Research paper (scientific journal), Single Work, Accepted

A unique photofunction of YVO4:Bi3+,Eu3+ nanophosphor: Photoluminescent indication for photochemical decomposition of polyurethane

H. Hara, S. Takeshita, T. Isobe, T. Sawayama,S. Niikura

Mater. Sci. Eng. B 178   311-315 2013.01

Research paper (scientific journal), Joint Work, Accepted

Down-sizing of YVO4:Bi3+,Eu3+ Nanoparticles through Hydrophobization by Surface Modification with Primary Alkylamines

Y. Iso, S. Takeshita, T. Isobe

Chem. Lett. 41 ( 12 ) 1681-1683 2012.12

Research paper (scientific journal), Joint Work, Accepted

Photoluminescence Properties of Green-Emitting YBO3:Ce3+,Tb3+ Phosphor for near UV Excitation

R. Sato, S. Takeshita, T. Isobe, T. Sawayama,S. Niikura

ECS J. Solid State Sci. Technol. 1 ( 6 ) R163-R168 2012.09

Research paper (scientific journal), Joint Work, Accepted

Solvothermal synthesis of Zn2GeO4:Mn2+ nanophosphor in water/diethylene glycol system

S. Takeshita, J. Honda, T. Isobe, T. Sawayama,S. Niikura

J. Solid State Chem. 189   112-116 2012.04

Research paper (scientific journal), Joint Work, Accepted

Effects of YVO4:Bi3+,Eu3+ nanophosphors spectral down-shifter on properties of monocrystalline silicon photovoltaic module

Y. Iso, S. Takeshita, T. Isobe

J. Electrochem. Soc. 159 ( 3 ) J72-J76 2012.03

Research paper (scientific journal), Joint Work, Accepted

Low-temperature wet chemical precipitation of YVO4:Bi3+,Eu3+ nanophosphors via citrate precursors

S. Takeshita, T. Isobe, T. Sawayama,S. Niikura

Prog. Cryst. Growth Charact. Mater. 57   127–136 2011.12

Research paper (scientific journal), Joint Work, Accepted

Preparation of composite PMMA microbeads hybridized with fluorescent YVO4:Bi3+,Eu3+ nanoparticles

K. Akisada, Y. Noguchi, T. Isobe

IOP Conf. Series: Mater. Sci. Eng. 18   082014 2011.11

Research paper (scientific journal), Joint Work, Accepted

Preparation of Yb3+ doped GdPO4 nanoparticles by solution-based processing

T. Shimizu, T. Isobe

IOP Conf. Series: Mater. Sci. Eng. 18   032021 2011.11

Research paper (scientific journal), Joint Work, Accepted

Factors for determining photoluminescence properties of YBO3:Ce3+ phosphor prepared by hydrothermal method

H. Ogata, S. Takeshita, T. Isobe, T. Sawayama,S. Niikura

Opt. Mater. 33   1820–1824 2011.09

Research paper (scientific journal), Joint Work, Accepted

Wet chemical synthesis and photoluminescence properties of YVO4:Bi3+,Eu3+ nanophosphors

H. Ogata, S. Takeshita, T. Isobe, T. Sawayama,S. Niikura

IOP Conf. Series: Mater. Sci. Eng. 18   102021 2011.04

Research paper (scientific journal), Joint Work, Accepted

Improvement of the Photostability for YVO4:Bi3+,Eu3+ Nanoparticles Synthesized by the Citrate Route

S. Takeshita, T. Watanabe, T. Isobe, T. Sawayama,S. Niikura

Opt. Mater. 33   323-326 2011.01

Research paper (scientific journal), Joint Work, Accepted

Size-Tunable Solvothermal of Zn2GeO4:Mn2+ Nanophoshor in Water/Diethylene Glycol System

S. Takeshita, J. Honda, T. Isobe, T. Sawayama,S. Niikura

Cryst. Growth Design 10   4494-4500 2010.09

Research paper (scientific journal), Joint Work, Accepted

マルチモーダルイメージングを可能にする蛍光・磁気共鳴デュアル機能性ナノ粒子の開発動向

磯部 徹彦

レーザー研究 38 ( 6 ) 440-446 2010.06

Research paper (scientific journal), Single Work

波長変換用YVO4:Bi3+,Eu3+ナノ蛍光体の開発：太陽電池の変換効率の向上を目指して

磯部 徹彦

Material Stage 10 ( 3 ) 79-82 2010.06

Research paper (scientific journal), Single Work

Photostability of YAG:Ce3+ Nanophosphors Synthesized by Glycothermal Method

Y. Kamiyama, T. Hiroshima, T. Isobe, T. Koizuka, S. Takashima

J. Electrochem. Soc. 157 ( 5 ) J149-J154 2010.05

Research paper (scientific journal), Joint Work, Accepted

Effective Wavelength Conversion from Near-UV to Red for Photovoltaics: Potential of Transparent YVO4:Bi3+,Eu3+ Nanophosphor Film

S. Takeshita, K. Nakayama, T. Isobe, T. Sawayama, S. Niikura

Mater. Res. Soc. Symp. Proc. 1260   1260-T10-35 2010.04

Research paper (conference, symposium, etc.), Joint Work, Accepted

Effects of Citrate Additive on Transparency and Photostability Properties of YVO4:Bi3+,Eu3+ Nanophosphor

S. Takeshita,H. Ogata, T. Isobe, T. Sawayama,S. Niikura

J. Electrochem. Soc. 157 ( 3 ) J74-J80 2010.03

Research paper (scientific journal), Joint Work, Accepted

ドープ型無機ナノ蛍光体の開発と展望

磯部 徹彦

Jasco Report 51 ( 1 ) 19-24 2009.09

Research paper (scientific journal), Single Work

Optical properties of transparent wavelength conversion film prepared from YVO4:Bi3+,Eu3+ nanophosphors

S. Takeshita, T. Isobe, T. Sawayama, S. Niikura

J. Electrochem. Soc. 156 ( 9 ) J273-J277 2009.09

Research paper (scientific journal), Joint Work, Accepted

Glycothermal synthesis and characterization of scheelite-type NaEuW2O8 nanophosphors

R. Kasuya, T. Isobe

J. Electrochem. Soc. 156 ( 9 ) J278-J282 2009.09

Research paper (scientific journal), Joint Work, Accepted

Effects of the homogeneous Bi3+ doping process on photoluminescence properties of YVO4:Bi3+,Eu3+ nanophosphor

S. Takeshita, T. Isobe, T. Sawayama, S. Niikura

J. Lumin. 129   1067-1072 2009.06

Research paper (scientific journal), Joint Work, Accepted

Glycothermal Synthesis and Photoluminescence of MgGa2O4:Mn2+ Nanophosphors: Comparison with ZnGa2O4:Mn2+ Nanophosphors

M. Takesada, M. Osada, T. Isobe

J. Electrochem. Soc. 156 ( 5 ) J97-J101 2009.05

Research paper (scientific journal), Joint Work, Accepted

Photobleaching Properties of YVO4:Eu3+ Nanophosphors Synthesized by Hydrothermal Treatment

T. Muto, S. Takeshita, T. Isobe, T. Sawayama, S. Niikura

ECS Transactions 16 ( 31 ) 135-140 2009.04

Research paper (international conference proceedings), Joint Work, Accepted

Preparation and Biological Application of Fluorescent Poly(methyl methacrylate) Beads Hybridized with Y3Al5O12:Ce3+ Nanophosphor

I. Kusayama, R. Asakura, D. Saito, T. Isobe, K. Kurokawa, H. Aizawa, T. Takagi, Y. Hirayama, M. Ohkubo

ECS Transactions 16 ( 31 ) 69-74 2009.04

Research paper (international conference proceedings), Joint Work, Accepted

Comparison between MgGa2O4:Mn2+ and ZnGa2O4:Mn2+ Nanophosphors Synthesized by Glycothermal Method

M. Osada, M. Takesada, T. Isobe

ECS Transactions 16 ( 31 ) 75-80 2009.04

Research paper (international conference proceedings), Joint Work, Accepted

蛍光ー磁性マルチ機能性プローブの作製とイメージング応用

朝倉亮、坂根宏志、磯部徹彦、森田将史、犬伏俊郎

JSMI Report 2 ( 1 ) 13-16 2009.01

Research paper (scientific journal), Joint Work

Characterization of ZnGa2O4:Mn2+ Nanophosphor Synthesized by Solvothermal Method in 1,4-Butanediol – Water System

M. Takesada, M. Osada, T. Isobe

J. Phys. Chem. Solids 70   281-285 2009.01

Research paper (scientific journal), Joint Work, Accepted

Characterization and Biological Application of YAG:Ce3+ Nanophosphor Modified with Mercaptopropyl Trimethoxy Silane

A. Tsukamoto, T. Isobe

J. Mater. Sci. 44   1344-1350 2009.01

Research paper (scientific journal), Joint Work, Accepted

生体分子ラベル用ナノ蛍光体に関する研究

磯部 徹彦

応用物理 77 ( 12 ) 1415-1424 2008.12

Research paper (scientific journal), Single Work, Accepted

Fluorescent and Magnetic Resonance Imaging by Rare Earth Doped Nanoparticles with Garnet Structure

R. Asakura, H. Sakane, K. Noda, T. Isobe, M. Morita, T. Inubushi

Mater. Res. Soc. Symp. Proc. 1064   1064-PP03-06 2008.11

Research paper (international conference proceedings), Joint Work, Accepted

逆ミセルのナノ反応場を利用したナノ蛍光体の作り方 －見た目は透明、紫外線を当てると光るナノ粒子－

磯部 徹彦

化学と教育 56 ( 11 ) 550-551 2008.11

Research paper (scientific journal), Single Work

インビジブルなナノ蛍光体の開発と展望

磯部 徹彦

化学工学誌 72 ( 7 ) 356-358 2008.07

Research paper (scientific journal), Joint Work

Low-Temperature Wet Chemical Synthesis and Photoluminescence Properties of YVO4:Bi3+,Eu3+ Nanophosphors

Satoru Takeshita, Tetsuhiko Isobe and Seiji Niikura

J. Lumin. 128   1515-1522 2008.07

Research paper (scientific journal), Joint Work, Accepted

　View Summary

365nm励起にて赤色発光する透明なYVO4 : Bi3+, Eu3+ナノ粒子分散液の低温液相合成を検討し、その蛍光特性を評価した。

ナノ蛍光体の研究開発の現状と課題

磯部 徹彦

照明学会誌 92 ( 6 ) 297-300 2008.06

Research paper (scientific journal), Single Work

Low Temperature Wet Chemical Synthesis of Nanophosphors in the Presence of Coordinating Molecules

ISOBE TETSUHIKO

Proc. 14th Intl. Display Workshops '07    2127-2130 2007.12

Research paper (scientific journal), Single Work

Characteristic optical properties of transparent color conversion film prepared from YAG:Ce3+ nanoparticles

R. Kasuya, A. Kawano, T. Isobe, H. Kuma and J. Katano

Appl. Phys. Lett. 91 ( 11 ) 111916-1～3 2007.09

Research paper (scientific journal), Joint Work, Accepted

Glycothermal Synthesis of Scheelite-Type LiEuW2O8 Nanophosphors and their Structural Characterization

R. Kasuya, T. Isobe and S. Yamao

Jpn. J. Appl. Phys. 46 ( 9A ) 5879-5884 2007.09

Research paper (scientific journal), Joint Work, Accepted

Preparation of Fluorescent Poly(methyl methacrylate) Beads Hybridized with Y3Al5O12:Ce3+ Nanophosphor for Biological Application

R. Asakura, I. Kusayama, D. Saito, T. Isobe, K. Kurokawa, Y. Hirayama, H. Aizawa, T. Takagi, M. Ohkubo

Jpn. J. Appl. Phys. 46 ( 8A ) 5193-5195 2007.08

Research paper (scientific journal), Joint Work, Accepted

Effects of citric acid additive on photoluminescence properties of　YAG:Ce3+ nanoparticles synthesized by glycothermal reaction

R. Asakura, T. Isobe, K. Kurokawa, T. Takagi, H. Aizawa, M. Ohkubo

J. Lumin. 127   416-422 2007.08

Research paper (scientific journal), Joint Work, Accepted

Effects of Post Calcination Treatment on Photoluminescence and Structural Properties of Scheelite-type LiEuW2O8 Nanocrystals Synthesized by Glycothermal Reaction

R. Kasuya, T. Isobe, S. Yamao, H. Sfihi

Mater. Res. Soc. Symp. Proc. 951   0951-E03-29 2007.06

Research paper (scientific journal), Joint Work, Accepted

Glycothermal Synthesis of ZnGa2O4:Mn2+ Nanophosphor and Change in its Photoluminescence Intensity by Heat Treatment

M. Takesada, T. Isobe, H. Takahashi, S. Itoh

J. Electrochem. Soc. 154 ( 4 ) J136-J140 2007.04

Research paper (scientific journal), Joint Work, Accepted

Glycothermal Synthesis and Magnetic Properties of YIG/YAG Nanoparticles

K. Noda, R. Asakura, T. Isobe, M. Morita,K. Kurokawa, T. Inubushi, T. Takagi and M. Ohkubo

Solid State Phenomena Journal 124-126   863-866 2007.01

Research paper (scientific journal), Joint Work, Accepted

Tagging of avidin immobilized beads with biotinylated YAG:Ce3+ nanocrystal phosphor

R. Asakura, T. Isobe, K. Kurokawa, H. Aizawa, M. Ohkubo

Analytical and Bioanalytical Chemistry 286   1641-1647 2006.11

Research paper (scientific journal), Joint Work, Accepted

Photoluminescence and chemical properties of ZnS:Mn2+ nanocrystal powder synthesized in the AOT reverse micelles modified with lauryl phosphate

H. Sfihi, H. Takahashi, W. Sato, T. ISOBE

J. Alloys Compd. 424   187-192 2006.10

Research paper (scientific journal), Joint Work

Low-temperature wet chemical synthesis of nanocrystal phosphors with surface modification and their characterization

T. Isobe

physica status solidi (a) 203 ( 11 ) 2686-2693 2006.08

Research paper (scientific journal), Single Work, Accepted

YAG:Ce3+ナノ蛍光体の低温液相合成と特性

ISOBE TETSUHIKO

月刊ディスプレイ    23-28 2006.06

Research paper (scientific journal), Single Work

Low-temperature synthesis and photoluminescence of IIA-VIB nano-phosphors doped with rare earth ions

N. Sawada, Y. Chen, T. ISOBE

J. Aollys Compd. 408-412   824-827 2006.01

Research paper (scientific journal), Joint Work, Accepted

Glycothermal synthesis and photoluminescence of YAG:Ce3+ nanophosphors

R. Kasuya, T. ISOBE, H. Kuma

J. Aollys Compd. 408-412   820-823 2006.01

Research paper (scientific journal), Joint Work, Accepted

Effects of surface modification on photoluminescence properties of LaPO4:Ce,Tb nano-phosphor synthesized by solvothermal reaction

ISOBE TETSUHIKO

Proc. Intl. Display Workshop ’05    513-516 2005.12

Research paper (international conference proceedings), Single Work

Photoluminescence Enhancement of PEG-modified YAG:Ce3+ Nanocrystal Phosphor Prepared by Glycothermal Method

R. Kasuya, T. ISOBE, H. Kuma, J. Katano

J. Phys. Chem. B 109 ( 47 ) 22126-22130 2005.11

Research paper (scientific journal), Joint Work, Accepted

Kinetic Analysis on the Photoluminescence Enhancement of MPS-Modified ZnS:Mn2+ Nanocrystal Colloidal Solution by Aging Effect

N. Sawada, Y. Hattori, T. ISOBE, H. Takahashi, S. Itoh

Jpn. J. Appl. Phys. 44 ( 11 ) 8032-8034 2005.11

Research paper (scientific journal), Joint Work, Accepted

固体素子照明における透明ナノ蛍光体への期待

ISOBE TETSUHIKO

Material Stage  ( 6 ) 7-14 2005.09

Research paper (scientific journal), Single Work

Luminescent properties of ZnS:Mn2+ nanocrystals / SiO2 hybrid phosphor synthesized by in situ surface modification co-precipitation

Y. Hattori, T. ISOBE, H. Takahashi, S. Itoh

J. Lumin. 113   69-78 2005.04

Research paper (scientific journal), Joint Work, Accepted

Characterization on thermal stability of ZnS:Mn2+/MPS/SiO2 nano-phosphor film

H. Kubo, T. ISOBE, H. Takahashi, S. Itoh

Appl. Surf. Sci. 244   465-468 2005.03

Research paper (scientific journal), Joint Work, Accepted

Photoluminescence Enhancement of ZnS:Mn2+ Nanocrystal Phosphors: Comparison of Organic and Inorganic Surface Modifications

H. Takahashi, T. ISOBE

Jpn. J. Appl. Phys. 44 ( 2 ) 922-925 2005.02

Research paper (scientific journal), Joint Work, Accepted

透光性ナノ蛍光体の応用

ISOBE TETSUHIKO

機械の研究 57 ( 1 ) 175-181 2005.01

Research paper (scientific journal), Single Work

Photoluminescent Properties and Local Structural Analysis of ZnS:Mn2+ Nanocrystal Phosphors Modified with 2-Mercaptoethanol

中村江美，磯部徹彦、石塚　雅之，中野　豊将，斉藤　光正

Proc. Int. Display Workshop '04 - ( - ) 1131-1134 2004.12

Research paper (scientific journal), Joint Work

　View Summary

メルカプトエタノール(ME)による表面修飾と種々の熟成処理を施したZnS:Mn2+ナノクリスタル濃厚水分散液を合成し、同溶液から得られた粉末試料のMn2+の存在状態を電子スピン共鳴(ESR)によって解析し、発光特性との関連を検討した。(4頁）

Low-temperature synthesis of nanosize Zn2SiO4:Mn2+ phosphor from the precursor sol in supercritical ethanol and its optical propertie

T. Miki, T. Ogawa, T. ISOBE, H. Sfihi

J. Sol-Gel Sci. Technol. 31 ( 1-3 ) 73-77 2004.11

Research paper (scientific journal), Joint Work, Accepted

　View Summary

ソルボサーマル法によって前躯体ゾルからZn2SiO4:Mn2+ナノ蛍光体を合成し、その発光特性を評価した。(5頁）

透光性ナノ蛍光体の液相合成，発光特性と近未来への期待

ISOBE TETSUHIKO

光学 33 ( 11 ) 639-644 2004.11

Research paper (scientific journal), Single Work, Accepted

IIB-VIB族ナノクリスタル蛍光体に関する研究開発の進展

磯部徹彦、黒川清、藤本啓二

応用物理 72 ( 12 ) 1516-1521 2003.12

Research paper (scientific journal), Joint Work, Accepted

　View Summary

IIB－VIB族ナノクリスタルの半径をエキシトンボーア半径よりも小さくし，粒子表面に適当な表面修飾を施すと，量子閉じ込め効果によって粒径制御による励起波長の最適化や発光効率の増大などが可能となる．本稿では，ZnS:Mn2+およびCdSeを中心としたナノクリスタル蛍光体に関する最新の研究開発動向を紹介する．（6頁）

ドープ型ナノクリスタル蛍光体材料

ISOBE TETSUHIKO

未来材料 3 ( 7 ) 26-35 2003.07

Research paper (scientific journal), Single Work

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ドープ型ナノクリスタル蛍光体の粒子半径をエキシトンボーア半径よりも小さくして，かつ，適当な表面修飾を施すと，粒子が透明になったり，最適な励起波長を制御できたり，発光効率を向上できる．このようなナノサイズに特有な蛍光体の特性に関して紹介する．（10頁）

シリカ表面修飾によるドープ型ナノクリスタルの高発光効率化

ISOBE TETSUHIKO

照明学会誌 87 ( 4 ) 256-261 2003.04

Research paper (scientific journal), Single Work

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筆者らが進めているZnS:Mn2+ナノクリスタルにSiO2を制御して被覆する合成法の取り組みと発光特性に関して最新の結果を紹介する．（6頁）

Solid-state 1H and 27Al NMR studies of amorphous aluminum hydroxides

T. Isobe, T. Watanabe, J.B. d’Espinose de la Caillerie, A.P. Legrand, D. Massiot

J. Colloid Interface Sci. 261 ( - ) 320-324 2003.03

Research paper (scientific journal), Joint Work, Accepted

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アモルファス水酸化アルミニウムの局所構造を、高速スピンでの27Al-および1H-MAS-NMRおよびスピンエコー法とTRAPDOR法による1H-NMRにより解析した。（5頁）

UV-induced formation of [Fe(bpy)3]2+ complex and its confinement into silica fine particles

C. Nakanishi, S. Ikeda, T. Isobe, M. Senna

J. Sol-Gel Sci. Technol. 26 ( - ) 103-106 2003.01

Research paper (scientific journal), Joint Work, Accepted

Mechanism of UV irradiation induced photoluminescence enhancement effect on ZnS:Mn nanocrystals modified by poly(acrylic acid)

L. Sun, T. Isobe

Proc. Intl. Display Workshop ‘02 - ( - ) 939-942 2002.12

Research paper (conference, symposium, etc.), Joint Work

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ZnS:Mnナノクリスタル蛍光体のＵＶ照射による発光強度増大のメカニズムに関して追究した。

Role of molecular strain on the solid-state synthesis of coordination compounds from iron(II) chloride tetrahydrate and 1,10-phenanthroline under mechanical stress

T. Ohshita, D. Nakajima, A. Tsukamoto, T. Isobe, M. Senna, N. Yoshioka, H. Inoue

Ann.Chim. Sci. Mat. 27 ( 6 ) 91-101 2002.12

Research paper (scientific journal), Joint Work, Accepted

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塩化鉄(II)と1,10フェナントロリンの混合摩砕から1,10フェナントロリン鉄錯体が生成される固相合成メカニズムを追究した。（11頁）

Enhancement of photoluminescence for organic/inorganic hybrid phosphors of doped semiconductor nanocrystals

T. ISOBE

Recent Res. Devel. Mat. Sci. 3 ( - ) 441-456 2002.12

Research paper (scientific journal), Single Work

Low temperature synthesis of Zn2SiO4:Mn2+ nNanocrystal phosphor in supercritical ethanol and its photoluminescent properties

T. Miki, T. Isobe

Proc. 2002 Eurodisplay - ( - ) 755-758 2002.10

Research paper (international conference proceedings), Joint Work

Solid-state radical recombination and charge transfer across the boundary between indomethacin and silica under mechanical stress

T. Watanabe, S. Hasegawa, N. Wakiyama, F. Usui, A. Kusai, T. Isobe, M. Senna

J. Solid State Chem. 164 ( - ) 27-33 2002.08

Research paper (scientific journal), Joint Work, Accepted

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メカニカルストレス下におけるインドメタシンとシリカとの界面における固相ラジカル結合と電界移動に関して検討した。（7頁）

Electronic states of Mn2+ nanoparticle examined by EPR measurements and molecular calculation

S. Nagare, T. Isobe, M. Senna, T. Igarashi

Mat. Res. Soc. Symp. Proc. 704 ( - ) W6.4.1-W6.4.6 2002.06

Research paper (international conference proceedings), Joint Work, Accepted

Silica-[Fe(bpy)3]2+ composite particles with photo-responsive change of color and magnetic property

C. Nakanishi, S. Ikeda, T. Isobe, M. Senna

Mater. Res. Bull. 37 ( - ) 647-651 2002.05

Research paper (scientific journal), Joint Work, Accepted

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ゾルゲル法により塩化鉄と2,2'－ビピリジンを含むシリカ微粒子を調製した。シリカ中では標記錯体は形成しないが、ＵＶ照射によって中心鉄(III)イオンの配位子交換と還元が誘起されシリカ微粒子中で鉄(II)イオンが遊離し、2,2'－ビピリジンとの間に標記錯体が形成する。錯形成の結果、金属から配位子への電子移動により赤色を呈する。以上の機構により光応答性のシリカ微粒子を得た。(5頁)

Enhancement of photoluminescence of ZnS:Mn nanocrystals modified by surfactants with phosphate or carboxylic groups via a reverse micelle method

T. Kubo, T. Isobe, M. Senna

J. Lumin. 99 ( - ) 39-45 2002.05

Research paper (scientific journal), Joint Work, Accepted

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ZnS:Mnナノクリスタル蛍光体をリン酸基あるいはカルボキシル基を持つ界面活性剤とAOT界面活性剤とのハイブリッド逆ミセル中で合成した。共存官能基によってZnS:Mnの発光強度が増強することを見出した。（7頁）

Solid-state double nuclear magnetic resonance study of the local structure of calcium phosphate nanoparticles synthesized by a wet-mechanochemical reaction

T. Isobe, S. Nakamura, R. Nemoto, M. Senna, H. Sfihi

J. Phys. Chem.B 106 ( 20 ) 5169-5176 2002.05

Research paper (scientific journal), Joint Work, Accepted

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Ca(OH)2粉体をH3PO4水溶液に混合し、マルチリング型微粉砕機で処理して得られたヒドロキシアパタイトナノ粒子に関して、1Hおよび31P固体高分解能核磁気共鳴法によって局所構造解析を究明した。（8頁）

A thermoluminescence study on the state of Cl in ZnS:Ag by electron beam

T. Igarashi, T. Kusunoki, K. Ohno, T. Isobe, M. Senna

Mater. Res. Bull. Vol. 37 ( - ) 533-539 2002.02

Research paper (scientific journal), Joint Work, Accepted

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カソードルミネッセンスにおける電子線によるZnS:Ag,Clの劣化挙動をサーモルミネッセンスによって研究した。（7頁）

Synthesis of perovskite Pb(Zn1/3Nb2/3)O3 powders via a polymer complex solution route with a large excess of polyethylene glycol

W.S. Lee, T. Isobe, M. Senna

Ad. Powder Technol. Vol.13 ( No. 1 ) 43-54 2002.02

Research paper (scientific journal), Joint Work, Accepted

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ポリマー錯体法を用いて、Pb(NO3)2, ZnCl2, NbCl5およびポリエチレングリコール(PEG)を含む溶液からPb(Zn1/3Nb2/3)O3を作製した。PEGの添加量の増加によって、より低温でペロブスカイト相が出現することがわかった。（12頁）

Comparison between ZnO and Y2O3 nanosize particles for degradation protection of ZnS-based phosphor

T. Igarashi, T. Kusunoki, K. Ohno, T. Isobe, M. Senna

J. Electrochem. Soc. Vol. 148 ( No. 12 ) J59-J62 2001.12

Research paper (scientific journal), Joint Work, Accepted

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ZnSを母体とした蛍光体に、ZnOまたはY2O3をコロイド化学的にコーティングし、電子線照射による蛍光体の劣化挙動を比較検討した。（4頁）

蛍光体材料のナノサイズ化による発光の高量子効率化

磯部徹彦

応用物理 70 ( 9 ) 1087-1091 2001.09

Research paper (scientific journal), Single Work, Accepted

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逆ミセルを構成する界面活性剤の一部をカルボキシル基やリン酸基を持つ界面活性剤に置換すると、ZnS:Mn2+ナノ粒子の発光強度および発光量子収率が増大することを紹介した。（5頁）

Molecular dynamic-molecular orbital combined study on the solid state interfacial reaction under mechanical stressing.

M. Senna, Y. Fujiwara, T. Isobe, J. Tanaka

Solid State Ionics (Proc. 14th International Symposium on Reactivity of Solids) 141-142 ( - ) 31-38 2001.07

Research paper (scientific journal), Joint Work, Accepted

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MDおよびMO計算により、メカニカルストレス印加時の反結合性軌道と結合生成軌道のポプュレーションの変化を検討した。（8頁）

Stability of amorphous indomethacin compounded with silica

T. Watanabe, N. Wakiyama, F. Usai, M. Ikeda, T. Isobe, M. Senna

Int. J. Pharm. Vol. 226 ( - ) 81-91 2001.07

Research paper (scientific journal), Joint Work, Accepted

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混合粉砕および急冷によってシリカと複合化したインドメタシンの安定性に関して比較検討した。（11頁）

Stress-induced ligand field distortion and consequent multi-mode spin crossover in FeII(phen)2(NCS)2 and FeII[HB(pz)3]2

N. Tsuchiya, A. Tsukamoto, T. Ohshita, T. Isobe, M. Senna, N. Yoshioka, H. Inoue

Solid-State Sci. Vol. 3 ( No. 6 ) 705-714 2001.06

Research paper (scientific journal), Joint Work, Accepted

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FeII(phen)2(NCS)2 および FeII[HB(pz)3]2結晶性粉末固体に機械的な外部応力を印加して誘起されるスピンクロスオーバーの特性に関して追究した。（10頁）

Degradation proof modification of ZnS-based phosphors with ZnO nanoparticles

T. Igarashi, T. Kusunoki, K. Ohno, T. Isobe, M. Senna

Mater. Res. Bull. Vol. 36 ( - ) 1317-1324 2001.05

Research paper (scientific journal), Joint Work, Accepted

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ZnS:Ag,Cl蛍光体にZnOを離散的にコーティングしたときに電子線照射による劣化が低下することを報告した。（8頁）

有機／無機複合型ZnS:Mnナノクリスタル蛍光体の発光機構と局所構造解析

磯部 徹彦

表面科学 22 ( 5 ) 315-322 2001.05

Research paper (scientific journal), Single Work, Accepted

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有機／無機複合型ZnS:Mnナノクリスタル蛍光体の発光機構と、発光中心の周囲の局所構造との関係を解説した。（8頁）

Enhancement of photoluminescence of ZnS:Mn nanocrystals by hybridizing with polymerized acrylic acid

M. Konishi, T. Isobe, M. Senna

J. Lumin. Vol. 93 ( - ) 1-8 2001.05

Research paper (scientific journal), Joint Work, Accepted

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Mn2+を固溶したZnSナノクリスタルをメタクリル酸モノマーと複合化し、その後の80℃での熱処理によって重合すると、発光強度が増大することが明らかにされた。また、メタクリル酸のポリマーよりもモノマーで表面修飾する方が、発光強度増大効果が大きいことがわかった。（8頁）

Characterization of Mn2+coordination states in ZnS nanocrystal by EPR spectroscopy and related photoluminescence properties

T. Igarashi, M. Ihara, T. Kusunoki, K. Ohno, T. Isobe, M. Senna

J. Nanoparticle Res. Vol. 3 ( - ) 51-56 2001.05

Research paper (scientific journal), Joint Work, Accepted

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ポリメタクリル酸と複合化したZnS:Mnナノクリスタルに存在するMn2+の配位状態を電子常磁性スピン共鳴によって解析した。その結果、Mn2+には表面および内部の２つのサイトが存在し、表面サイトのMn2+にはカルボキシル基が配位していることが明らかにされた。（6頁）

Hydroxyapatite nano sol prepared via a mechanochemical route

S. Nakamura, T. Isobe, M. Senna

J. Nanoparticle Res. Vol. 3 ( - ) 57-61 2001.05

Research paper (scientific journal), Joint Work, Accepted

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結晶性ヒドロキシアパタイトが分散したゾルを、ポリアクリル酸アンモニウム分散剤共存下でCa(OH)2をH3PO4水溶液中で摩砕することによって合成できることを報告した。（5頁）

Direct synthesis of hydroxyapatite-silk fibroin nano-composite sol via a mechanochemical route

R. Nemoto, S. Nakamura, T. Isobe, M. Senna

J. Sol-Gel Sci. Technol. Vol. 21 ( - ) 7-12 2001.05

Research paper (scientific journal), Joint Work, Accepted

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シルクフィブロインの存在下でヒドロキシアパタイトナノ粒子の低粘度ゾルを湿式メカノケミカル法によって合成した（6頁）

Properties of hydroxyapatite-silk fibroin nano composite particles synthesized by a one-step wet mechanochemical reaction

根本励、中村智、磯部徹彦、仙名保

Proc. ATP 2000  2000.12

Research paper (international conference proceedings), Joint Work

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シルクフィブロイン(SF)と分散剤の存在下でのメカノケミカル反応によって、分散性の高いヒドロキシアパタイト－SF複合ナノ粒子が室温で合成できることを報告した。（4頁）

Synthesis of phase pure Pb(ZnxMg1-x)1/3Nb2/3O3 up to x=0.7 from a single mixture via a soft-mechanochemical route

S. Shinohara, J.G. Baek, T. Isobe, M. Senna

J. Am. Ceram. Soc. 83 ( 12 ) 3208-3210 2000.12

Research paper (scientific journal), Joint Work, Accepted

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PbO, Mg(OH)2, Nb2O5, 2ZnCO33Zn(OH)2を混合摩砕し、1100℃1hかねつして、Pb(ZnxMg1-x)1/3Nb2/3O3ペロブスカイト単相をX≦0.7の範囲で合成できることを報告した。（3頁）

Preparation of silica-silk fibroin-polyurethane composite films via a sol-gel route

M. Tsujino, T. Isobe, M. Senna

J. Sol-Gel Sci. Technol. 19 ( - ) 785-789 2000.12

Research paper (scientific journal), Joint Work, Accepted

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シリカ、シルクフィブロイン、ポリウレタンを含むコンポジット膜を作成し、３成分の均一分散性や化学的な相互作用に関して検討した。（5頁）

Properties of hydroxyapatite nano sol prepared via a wet mechanochemical route

中村智、根本励、磯部徹彦、仙名保

Proc. ATP 2000  2000.12

Research paper (international conference proceedings), Joint Work

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Ca(OH)2粉体をH3PO4水溶液に混合し、マルチリング型微粉砕機で処理すると、ヒドロキシアパタイトのナノゾルが得られることを報告した。（5頁）

チタン酸鉛合成反応に対する原料混合ゾルへの超音波照射および摩砕の効果

大石 秀伸、仙名 保、磯部 徹彦、三留 秀人

粉体および粉末冶金 Vol. 47 ( No. 9 ) 1036-1038 2000.08

Research paper (scientific journal), Joint Work, Accepted

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チタニアゾルと酸化鉛ゾルに超音波および摩砕を行い、ペロブスカイト生成における相乗効果を検討した。（3頁）

Anomalous spin crossover of mechanically strained iron(II) complexes with 1,10-phenanthroline with their counterions, NCS- and PF6-

N. Tsuchiya, A. Tsukamoto, T. Ohshita, T. Isobe, M. Senna, N. Yoshioka, H. Inoue

J. Solid-State Chem. Vol.153 ( - ) 82-91 2000.08

Research paper (scientific journal), Joint Work, Accepted

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[Fe(phen)3](NCS)2H2Oと [Fe(phen)3](PF6)2に関するメカニカルストレスによる非晶質化によるカウンターイオンの影響に関して比較検討した。（10頁）

Preparation and properties of nanocrystalline ZnS:Mn-polymer composite films

T. Kezuka, M. Konishi, T. Isobe, M. Senna

J. Lumin. 87-89 ( - ) 418-420 2000.05

Research paper (scientific journal), Joint Work, Accepted

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PAAからZnS:Mnナノクリスタルへのエネルギー移動によりMn2+による発光強度が増大する。この点をより明確にするため、ZnS:MnをPMMAに分散した膜上にPAA膜を作製し、ZnS:Mnを分散したPAA膜と比較検討した。（3頁）

A molecular orbital study on the formation of　hetero-metalloxane bonds under mechanical stressing

藤原康裕、磯部徹彦、仙名保、田中順三

Mater. Sci. Forum. (Proc. 1999 International Conference on Metastable, Mechanically Alloyed and Nanocrystalline Materials) 343-346 ( - ) 447-452 2000.04

Research paper (scientific journal), Joint Work, Accepted

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CaOまたはCa(OH)2とSiO2との間のモデル反応において、ヘテロ結合Ca-O-Siが生成することがDV-Xa法による計算から示された。特に、Ca周囲の酸素の配位数が低下すると、ヘテロ結合がより容易になる。この計算結果は、メカノケミカル反応のXPS結果とよく対応する。（6頁）

Tris(1,10-phenanthroline-N,N’) iron(II) dithiocyanate trihydrate

G. Hoshina, S. Ohba, N. Tuchiya, T. Isobe, M. Senna

Acta Crystallogrphica Sec. C Vol. 56 ( - ) e191-e192 2000.04

Research paper (scientific journal), Joint Work, Accepted

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[Fe(C12H8N2)3](NCS)2 ・3H2Oの単結晶構造解析を行い、歪んだ八面体配位構造をとることが明らかにされた。（2頁）

Change in the short range order in the Al - transition metal hydroxides miexed system by mechanical stressing

関野省治、磯部徹彦、仙名保、篠原猛、我妻文彦、隅山兼治、鈴木謙爾

Mater. Sci. Forum. (Proc. 1999 International Conference on Metastable, Mechanically Alloyed and Nanocrystalline Materials) 343-346 ( - ) 441-446 2000.04

Research paper (scientific journal), Joint Work, Accepted

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AlとNi(OH)2あるいはCu(OH)2を摩砕することによって酸化還元反応を起こることをX線回折、27Alおよび63Cu核磁気共鳴、SQUID磁化測定によって明らかにした。（6頁）

Relationship between optical properties and crystallinity of nanometer Y2O3:Eu phosphor

五十嵐崇裕、 井原優、 楠木常夫、 大野勝利、磯部徹彦，仙名保

Appl. Phys. Lett. Vol.76 ( No.12 ) 1549-1551 2000.03

Research paper (scientific journal), Joint Work, Accepted

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直径61nmのEu3+ を固溶したY2O3 (Y2O3:Eu)を合成した。S6 対称およびC2 対称のEu3+ の5D0→7F1a 遷移によるフォトルミネッセンスが582nmと587nmに観測される。ナノサイズ化による表面原子の再配列とEu-Oのイオン結合性の増大によって、励起スペクトルがブルーシフトした。（3頁）

A molecular orbiral approach toward soft-mechanochemical synthesis from the view point of hetero-metalloxane bonding under mechanical stressing

藤原康裕、磯部徹彦、仙名保、田中順三

Trans. Mater. Res. Soc. Jpn. 25 ( 1 ) 139-142 2000.01

Research paper (scientific journal), Joint Work, Accepted

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DV-Xa法を用いて、Ca(OH)2とSiO2との接近に伴って、ヘテロ結合Ca-O-Siが生成することが示された。特に、Ca周囲の酸素の配位数が低下すると、ヘテロ結合がより容易になる。この計算結果は、メカノケミカル反応の結果とよく対応する。（4頁）

An X-ray photoelectron study on mechanochemical reactions toward ferroelectric lead zinc niobate

李禾燮、磯部徹彦、仙名保

Trans. Mater. Res. Soc. Jpn. 25 ( 1 ) 135-138 2000.01

Research paper (scientific journal), Joint Work, Accepted

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PbO, 2ZnCO3・3Zn(OH)2・H2O, Nb2O5をメカノケミカル反応させたときの初期段階における電荷移動をX光電子分光法によって解析した。その結果、摩砕によって、Pb-O-NbおよびPb-O-Zn結合が形成されることが示唆された。（4頁）

Effects of Reduced Coordination Number for Ca on the Electron Redistribution during Ca-O-Si Bridge Bonding from CaO or Ca(OH)2 and SiO2

藤原康裕、磯部徹彦、仙名保、田中順三

J. Phys. Chem. A Vol.103 ( No. 48 ) 9842-9846 1999.12

Research paper (scientific journal), Joint Work, Accepted

　View Summary

DV-Xa法を用いて、Ca(OH)2とSiO2との接近に伴って、ヘテロ結合Ca-O-Siが生成することが示された。特に、Ca周囲の酸素の配位数が低下すると、ヘテロ結合がより容易になる。この計算結果は、メカノケミカル反応の結果とよく対応する。（5頁）

Formation of SrVO3 precursors from Sr(OH)2 and VmOn (2/5 ≦m/n ≦ 2/3) by mechanical stressing under ambient or reducing atmosphere

李禾燮、磯部徹彦、仙名保

Solid State Ionics Vol.123 ( No.1-4 ) 293-300 1999.07

Research paper (scientific journal), Joint Work, Accepted

　View Summary

Sr(OH)2 と VmOn (2/5 ≦m/n ≦ 2/3)とのメカノケミカル反応およびその後の大気中および還元雰囲気中の加熱によってSrVO3の合成を試みた。その結果、３価と５価のV2O3とV2O5を用いて、還元雰囲気中で加熱する方法が最もよいことが明らかにされた。（4頁）

History dependent electrorheological properties of non-aqueous silica suspension

長谷川雄介、磯部徹彦、仙名保、大坪泰文

Nihon Reoroji Gakkaishi Vol. 27 ( No. 2 ) 131-132 1999.07

Research paper (scientific journal), Joint Work, Accepted

　View Summary

シリカを分散した非水溶系サスペンションの電気レオロジー(ER)挙動には、シリカ表面状態に依存した時間依存性があることがわかった。（2頁）

Enhanced photoluminescence for ZnS nanocrystals doped with Mn2+ close to carboxyl groups and/or S2- vacancies

磯部徹彦、五十嵐崇裕、小西美穂、仙名保

Proc. 1998 MRS fall meeting, Mat. Res. Soc. Symp. Proc. Vol. 536   383-388 1999.06

Research paper (international conference proceedings), Joint Work, Accepted

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ZnSにドープしたMn2+の近傍に存在するカルボキシル基やS2-の欠陥が発光強度増大に寄与することを明らかにした。（6頁）

Controlled dissolution of phenytoin by hybridizing with silica nanoparticles

後藤晴美、磯部徹彦、仙名保

J. Nanopart. Res. Vol.1   205-213 1999.06

Research paper (scientific journal), Joint Work, Accepted

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TEOS加水分解・縮重合過程に難溶性薬物フェニトイン(PT)を投入し、シリカー薬物ハイブリッドを合成した。シリカとの複合化によって、PTの溶解速度が40倍も増大した。これは、PT分子間結合が弱まり、シリカとPTとの間に新たな結合が生成にしたことに起因する。（9頁）

Change in the short range order in the Al - g-MnOOH miexed system by mechanical stressing

関野省治、磯部徹彦、仙名保、篠原猛、我妻文彦、隅山兼治、鈴木謙爾

Mater. Sci. Forum. (Proc. ISMANAM-1998 (1998 International Conference on Metastable, Mechanically Alloyed and Nanocrystalline Materials) Vol. 312-314   363-368 1999.04

Research paper (international conference proceedings), Joint Work, Accepted

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Alとg-MnOOHを摩砕することによって酸化還元反応を起こることをX線回折、27Al核磁気共鳴、ESR、SQUID磁化測定によって明らかにした。（6頁）

(Ba,Sr)TiO3 solid solution thin-films grown by a molecular beam epitaxy method

河野哲夫、磯部徹彦、仙名保、西原、田中順三

Thin Solid Films Vol. 352   57-61 1999.04

Research paper (scientific journal), Joint Work, Accepted

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分子線エピタキシーによってSrTiO3 (001)基板上に(Ba,Sr)O 層とTiO2 層を交互に20回積層して8 nmの膜厚を有する(Ba,Sr)TiO3 薄膜を作製した。膜生成過程をRHEEDおよびAFMによって解析した結果、縞状成長することが明らかにされた。CAICISSによる解析より、Sr/Ba比が増大すると表面原子配列が改善されることがわかった。（5頁）

Physical and chemical interactions in multi-component composite particles prepared by mechanical stressing

網健作、磯部徹彦、仙名保

Powder Technol. 100   46-51 1998.12

Research paper (scientific journal), Joint Work, Accepted

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メカニカルストレスによって調製した多成分コンポジット粒子の物理的・化学的相互作用を検討した。（6頁）

Optical properties of polycarboxylic acid / ZnS:Mn nanocrystal hybrid phosphors

小西美穂、五十嵐崇裕、磯部徹彦、仙名保

Proc. PTF/AIChE Topical Conference on Advanced Technological for Particle Processing  1998.11

Research paper (international conference proceedings), Joint Work

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ZnS:Mnをポリアクリス酸と複合化したハイブリッド蛍光体の光特性を報告した。（6頁）

Effects of KrF laser irradiation on Bi nanoclusters embedded in a-SiO2 by ion implantation

S.Y. Park，磯部徹彦，仙名保，R.A. Weeks，R.A. Zuhr

Appl. Phys. Lett. 73 ( 18 ) 2687-2689 1998.11

Research paper (scientific journal), Joint Work, Accepted

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イオン注入によってアモルファスシリカ中に生成したBiナノクラスターへのKrFレーザー照射の効果を報告した。（3頁）

Preparation and properties of polymer microspheres dispersed in a silica gel film

足立麻衣子、磯部徹彦、仙名保

Colloids and Surf. A, Physiochem. Eng. Aspects Vol. 153   617-623 1998.10

Research paper (scientific journal), Joint Work, Accepted

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シリカゲル膜に分散したポリマーミクロスフェアを調製し、その特性を報告した。（7頁）

Controlled dissolution of phenytoin by complexing with silica nanoparticles modified by acrylamide.

後藤晴美，磯部徹彦，仙名保

Proc. Int. Conf. Silica Science and Technology From S (Synthesis) to A (Application),(CNRS, Mulhouse, 1998)    573-576 1998.09

Research paper (international conference proceedings), Joint Work

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フェニトイン薬物をシリカナノ粒子と複合化して溶解速度を制御することを報告した。（4頁）

Surface modification of silica glasses by sequential ion-implantation of ferromagnetic components in the Fe-B system.

磯部徹彦，中島朋紀，仙名保，R.A. Weeks，R.A. Zuhr

Proc. Int. Conf. Silica Science and Technology From S (Synthesis) to A (Application),(CNRS, Mulhouse, 1998)    237-240. 1998.09

Research paper (international conference proceedings), Joint Work

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強磁性Fe-B系成分をシリカガラスへイオン注入して表面修飾することを報告した。（4頁）

Chemical interaction between nitrogen and iron in silica glasses via sequential ion-implantation.

磯部徹彦，鳥山保，R.A. Weeks，R.A. Zuhr

J. Mater. Res. 13 ( 8 ) 2144-2150 1998.08

Research paper (scientific journal), Joint Work, Accepted

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シリカガラスへの２重イオン注入による窒素と鉄との間の化学的相互作用を報告した。（7頁）

Preparation and properties of phenytoin silica complex nanoparticles

後藤晴美，磯部徹彦，仙名保

Mat. Res. Soc. Symp. Proc. (MRS, 1997 MRS Fall Meeting, Boston) 501   321-326 1998.07

Research paper (international conference proceedings), Joint Work, Accepted

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フェニトイン薬物とシリカナノ粒子との複合化の方法とその特性を報告した。（6頁）

Better ferroelectric ceramics starting from a soft mechanochemical route

白種甲，五味健二郎，渡部知行，磯部徹彦，仙名保

Proc. 2nd Int. Conf. Mechanochem. and Mechanical Activation, Chem. Sustainable Develop 6 ( 2-3 ) 159-163 1998.06

Research paper (international conference proceedings), Joint Work

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ソフトメカノケミカル法による高性能強誘電体セラミックスの合成を報告した。（4頁）

Electronegativity equalization during mechanochemical addition reaction

渡部知行，磯部徹彦，仙名保

Proc. 2nd Int. Conf. Mechanochem. and Mechanical Activation, Chem. Sustainable Develop. 6 ( 2-3 ) 164-168 1998.06

Research paper (international conference proceedings), Joint Work

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メカノケミカル付加反応中の電気陰性度均等化を報告した。（4頁）

Preparation of tricalcium phosphate by applying grinding technique and choosing hydroxy-containing initial materials

廖捷凡，小野，金山学，磯部徹彦，仙名保

Proc. 2nd Int. Conf. Mechanochem.and Mechanical Activation,Chem. Sustainable Develop. 6 ( 2-3 ) 233-236 1998.06

Research paper (international conference proceedings), Joint Work

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OH基を有する出発物質の摩砕によるリン酸カルシウムの合成を報告した。（4頁）

Reduction and change of magnetic properties of Co(OH)2 on milling with Al

亀井利道，磯部徹彦，仙名保，篠原猛，我妻文彦、隅山兼治，鈴木謙爾

Proc. Int. Symp. Mechanically Alloyed, Metastabe and Nanocrystalline Materials, Mater. Sci. Forum 269-272   247-252 1998.05

Research paper (international conference proceedings), Joint Work

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AlとのミリングによるCo(OH)2 の還元および磁気特性の変化を報告した。（6頁）

Quantitative description of the microstructure and its relationship to the critical current density of Ag-sheathed Bi(2223).

土屋朋也，磯部徹彦，仙名保，伊藤満，小泉勉

Solid State Ionics 108   321-326 1998.05

Research paper (scientific journal), Joint Work, Accepted

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AgシースBi(2223)の微細構造と臨界電流密度との間の関係を定量的に評価する方法を報告した。（6頁）

Magnetic properties of nanosize nickel particles produced insilica glasses by ion-implantation and subsequent annealing.

磯部徹彦，R.A. Weeks，R.A. Zuhr

Solid State Commun. 105 ( 7 ) 469-472 1998.01

Research paper (scientific journal), Joint Work, Accepted

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イオン注入およびその後の加熱によってシリカガラスに生成したNiナノサイズ粒子の磁気的性質を報告した。（4頁）

Mechanisms of multi-componet perovskite synthesis from stoichiometric mixtures by a soft-mechanochemical route

白種甲，五味健二郎，渡部知行，磯部徹彦，仙名保

Proc. Int. Symp. Metastable, Mechanically Alloyed and Nanocrystalline Materials, Mater. Sci. Forum 235-238   115-120 1997.12

Research paper (international conference proceedings), Joint Work

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ソフトメカノケミカル法によって化学量論比の出発混合物から多成分ペロブスカイトが生成するメカニズムを報告した。（6頁）

Nanocrystalline ZnS: Mn phosphor from solutions containing carboxylic acids.

仙名保，五十嵐崇裕，小西美穂，磯部徹彦

Proc. Fourth Int. Display Workshop, (ITE&SID, Nagoya, 1997)    613-616 1997.11

Research paper (international conference proceedings), Joint Work, Accepted

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カルボン酸を含有する溶液からZnS:Mnナノ結晶蛍光体を合成するプロセスを報告した。（4頁）

NMR and EPR studies on the charge transfer and formation of complexes through incompletely coordinated states

仙名保，磯部徹彦

Solid State Ionics 101-103   387-392 1997.10

Research paper (scientific journal), Joint Work, Accepted

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不完全配位状態の複合体の電荷移動と生成機構をNMRとEPRによって解析したことを報告した。（6頁）

Flat dielectric properties of capacitor (1-x)Pb(Mg1/3Nb2/3) O3-xPbTiO3 by controlled concentration gradient.

白種甲, 五味健二郎, 磯部徹彦，仙名保

Mater. Sci. Eng. B 49   46-52 1997.10

Research paper (scientific journal), Joint Work, Accepted

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(1-x)Pb(Mg1/3Nb2/3) O3-xPbTiO3キャパシターの濃度勾配を制御して温度依存性のないフラット誘電特性を持つデバイスを製造できることを報告した。（7頁）

EPR study of Mn2+ electronic states for the nanosized ZnS:Mn powder modified by acrylic acid

五十嵐崇裕， 磯部徹彦，仙名保

Phys. Rev., B 56 ( 11 ) 6444-6445 1997.10

Research paper (scientific journal), Joint Work, Accepted

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アクリル酸によって表面処理したZnS:Mnナノサイズ粉体のMn2+の電子状態をEPRによって解析したことを報告した。（2頁）

Enhanced densification of indium-tin oxide ceramics for sputter target through wet mechanochemical processing

岩佐航一郎，磯部徹彦，仙名保

Solid State Ionics 101-103   71-78 1997.10

Research paper (scientific journal), Joint Work, Accepted

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ウエットメカノケミカルプロセスによるスパッタ用ITOターゲットの緻密化促進を報告した。（8頁）

Mechanism of incipient chemical reaction between Ca(OH)2 and SiO2 under moderate mechanical stressing. III. Changes in the short range ordering throughout the mechanical and thermal processes

渡部知行, 磯部徹彦，仙名保

J. Solid State Chem. 130   284-289 1997.08

Research paper (scientific journal), Joint Work, Accepted

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Ca(OH)2 とSiO2との間のメカニカル複合化とその後の加熱による反応によって短距離秩序の変化を報告した。（6頁）

Effects of Mn2+ distribution controlled by carboxylic acids on photoluminescence intensity of nanosized ZnS:Mn particles.

磯部徹彦，五十嵐崇裕，仙名保

Mat. Res. Soc. Symp. Proc. 452, , (MRS, 1997 MRS Fall Meeting, Boston)    305-310 1997.04

Research paper (international conference proceedings), Joint Work, Accepted

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カルボン酸添加によってMn2+ 分布を制御し、ZnS:Mnナノサイズ微粒子のフォトルミネッセンスを向上させることを報告した。（6頁）

Synthesis of pyrochlore-free 0.9Pb(Mg1/3Nb2/3)O3-0.1PbTiO3 ceramics via a soft mechanochemical route

白種甲，磯部徹彦，仙名保

J. Am. Ceram. Soc. 80 ( 4 ) 973-981 1997.04

Research paper (scientific journal), Joint Work, Accepted

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パイロクロア相を含まない0.9Pb(Mg1/3Nb2/3)O3-0.1PbTiO3セラミックスをソフトメカノケミカル合成する手法を報告した。（9頁）

Properties of composite films comprising surface modified fine collagen particles dispersed in polyurethane matrix

中島義夫，磯部徹彦，仙名保

J. Appl. Polymer Sci. 63 ( 12 ) 1693-1700 1997.03

Research paper (scientific journal), Joint Work, Accepted

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ポリウレタンマトリックス中に分散した表面処理したコラーゲン微粒子から成るコンポジット膜の性質を報告した。（8頁）

Reactive sintering for oriented and connected Bi-2223 superconductive oxide from a mixture of delaminated Bi-2212 and fine powdered supplemental ingredients.

樫村猛伯，磯部徹彦，仙名保，伊藤満，小泉勉

Adv. Supercond. VIII, Proc. Int. Symp. Supercond. 8th,Vol. 1, (Springer, Tokyo, 1996)    405-408. 1997.01

Research paper (international conference proceedings), Joint Work, Accepted

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剥離したBi-2212と微粉体補足相との混合物から配向したBi-2223超電導酸化物の反応焼結プロセスを報告した。（4頁）

An XAFS study on reconstruction of short-range order in mechanically alloyed Al-Ti and Al-Ti-O complexes

小島優美，磯部徹彦，仙名保，桜井雅樹，隅山兼治，鈴木謙爾

J. Alloys Compd. 248   52-58 1997.01

Research paper (scientific journal), Joint Work, Accepted

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Al-TiおよびAl-Ti-O系メカニカル複合体の短距離秩序の再編成プロセスをXAFSによって解析したことを報告した。（7頁）

Optical properties of homogeneously Mn-doped ZnS nanoparticles

劉一，磯部徹彦，仙名保，高橋信一

J. Soc. Information Display 4 ( 4 ) 361-364 1996.12

Research paper (scientific journal), Joint Work, Accepted

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Mn2+を均一にドープしたZnS微粒子の光学的性質を報告した。（4頁）

Mechanochemical effects on the precursor formation and microwave dielectric characteristics of MgTiO3

白種甲，磯部徹彦，仙名保

Solid State Ionics 90   269-279 1996.12

Research paper (scientific journal), Joint Work, Accepted

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MgTiO3前駆体の生成とマイクロ波誘電特性へのメカノケミカル効果を報告した。（11頁）

A redox reaction between fine particulate Al and TiO2 H2O during milling.

小島優美，磯部徹彦，仙名保，篠原猛，小野陲，隅山兼治，鈴木謙爾

Proc. Int. Symp. Metastable, Mechanically Alloyed and Nanocrystalline Materials, Mater. Sci. Forum, 225-227   569-574 1996.10

Research paper (international conference proceedings), Joint Work, Accepted

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ミリング中の AlとTiO2 H2Oとの間の酸化還元反応を報告した。（6頁）

Reactive sintering for oriented and connected Bi-2223 superconductive oxides from a mixture of delaminated Bi-2212 and fine powdered supplemental ingredients.

樫村猛伯，磯部徹彦，仙名保，伊藤満，小泉

Physica C 270   297-304 1996.10

Research paper (scientific journal), Joint Work, Accepted

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剥離したBi-2212と微粉体補足相との混合物から配向したBi-2223超電導酸化物の反応焼結プロセスを報告した。（8頁）

Direct verification of incipient mechanochemical interaction between two metallic species mediated by OH groups.

仙名保，渡部知行，磯部徹彦

Proc. Int. Symp. Metastable, Mechanically Alloyed and Nanocrystalline Materials, Mater. Sci. Forum 225-227   521-526 1996.10

Research paper (international conference proceedings), Joint Work, Accepted

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OH基を有する２種の出発物質間の初期メカノケミカル相互作用を報告した。（6頁）

Mechanochemical effects on the structures and chemical states of (Fe(Phen)3)(NCS)2H2O

土屋直子，磯部徹彦，仙名保，吉岡直樹，井上秀成

Solid State Commum. 99   525-529 1996.08

Research paper (scientific journal), Joint Work, Accepted

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(Fe(Phen)3)(NCS)2H2O錯体結晶の構造と化学的性質に対するメカノケミカル効果を報告した。（5頁）

Optical and magnetic properties of silica implanted with N+ and Fe+.

磯部徹彦，R.A. Weeks，R.A. Zuhr

Proc. Ion-Solid Interaction for Materials Modification and Processing (MRS, 1995 MRS Fall Meeting, Boston), Mat. Res. Soc. Symp. Proc. 396   411-416 1996.07

Research paper (international conference proceedings), Joint Work, Accepted

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N+ とFe+を注入したシリカの光学的および磁気的性質を報告した。（6頁）

Magnetic properties of ultrafine magnetic particles and their slurries prepared via in-situ precipitation

李知爰，磯部徹彦，仙名保

Colloid Surf. A Physicochem. Eng. Aspects 109   121-127 1996.07

Research paper (scientific journal), Joint Work, Accepted

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その場合成法によって調製した磁気微粒子とそのスラリーの磁気的性質を報告した。（7頁）

ソフトメカノケミカル複合化によるペロブスカイト単相0.9PMN-0.1PT複合酸化物の調製と生成機構

白種甲，五味健二郎，磯部徹彦，仙名保

粉体および粉末冶金 44   717-721 1996.06

Research paper (scientific journal), Joint Work, Accepted

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ソフトメカノケミカル複合化によってペロブスカイト単相0.9PMN-0.1PT複合酸化物を生成する機構を検討した。（5頁）

Optical properties and characteristics of ZnS: Mn prepared by Mn coating method

劉一，磯部徹彦，仙名保，高橋信一

Mater. Sci. Eng.B 38   177-181 1996.06

Research paper (scientific journal), Joint Work, Accepted

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Mnコーティング法によって合成したZnS:Mnの光学的性質と特性を報告した。（5頁）

Mechanisms of Al and titania hydrogel complex formation via a mechanical route.

小島優美，磯部徹彦，仙名保，篠原猛，小野陲，隅山兼治，鈴木謙爾

J. Mater. Res. 11   1305-1309 1996.06

Research paper (scientific journal), Joint Work, Accepted

　View Summary

メカニカル処理によるAlとチタニア水和ゲルとの複合化メカニズムを報告した。（5頁）

Mechanism of incipient chemical reaction between Ca(OH)2 and SiO2 under moderate mechanical stressing. II. Examination of a radical mechanism by an EPR study.

渡部知行， 磯部徹彦，仙名保

J. Solid State Chem. 122   291-296 1996.05

Research paper (scientific journal), Joint Work, Accepted

　View Summary

マイルドなメカニカルストレスによるCa(OH)2 とSiO2との間の初期複合化反応メカニズムをEPR測定から追究したことを報告した。（6頁）

Comparative studies of the mechanochemical synthesis of MgTiO3 precursors by milling various mixtures containing oxides and hydroxides.

浜田憲二，磯部徹彦，仙名保

J. Mater. Sci. Lett. 15   603-605 1996.04

Research paper (scientific journal), Joint Work, Accepted

　View Summary

酸化物および水酸化物の混合物を摩砕することによってMgTiO3 前駆体をメカノケミカル合成することを比較検討した。（3頁）

Optical properties and characteristics of ZnS nanoparticles with homogeneous Mn distribution.

劉一，磯部徹彦，仙名保

J. Phys. Chem. Solids 57   373-379 1996.03

Research paper (scientific journal), Joint Work, Accepted

　View Summary

Mn2+が均一に分散したZnSナノ粒子の光学的性質と特性を報告した。（7頁）

Mechanism of incipient chemical reaction between Ca(OH)2 and SiO2 under moderate mechanical stressing. I. A solid state acid-base reaction and charge transfer due to complex formation.

渡部知行，磯部徹彦，仙名保

J. Solid State Chem. 122   74-80 1996.03

Research paper (scientific journal), Joint Work, Accepted

　View Summary

マイルドなメカニカルストレスによるCa(OH)2 とSiO2との間の初期複合化反応は、固体酸塩基反応と電荷移動に起因することを報告した。（7頁）

Preparation of ultrafine Fe3O4 particles by precipitation in the presence of PVA at high pH.

李知爰，磯部徹彦，仙名保

J. Colloid Interface Sci. 177   490-494 1996.02

Research paper (scientific journal), Joint Work, Accepted

　View Summary

高pHでPVA共存下でFe3O4 超微粒子を合成することを報告した。（5頁）

Effects of mechanical pretreatment of precursor sols and gels on the formation of NiO/SiO2 composites with a controlled microstructure.

竹内勝彦，磯部徹彦，仙名保

J. Non-Cryst. Solids 194   58-62 1996.01

Research paper (scientific journal), Joint Work, Accepted

　View Summary

前駆体ゾルよびゲルのメカニカル前処理によってNiO/SiO2 コンポジットの微細構造を制御することを報告した。（5頁）

Incipient chemical reaction on the scratched silicon {111} surface with ethoxy and hydroxyl groups.

斉藤有理子，磯部徹彦，仙名保

J. Solid State Chem. 120   96-100 1995.11

Research paper (scientific journal), Joint Work, Accepted

　View Summary

エトキシ基およびOH基を持つシリコン {111} にスクラッチ傷を導入した時の初期化学反応を報告した。（5頁）

Topochemical processes of interaction of aluminum hydroxyl polycations into V2O5 xero gel films and particles.

森仁彦，磯部徹彦，仙名保

Solid State Ionics 81   157-163 1995.11

Research paper (scientific journal), Joint Work, Accepted

　View Summary

V2O5キセロゲル薄膜および粒子に水和アルミニウムポリカチオンを挿入するプロセスに関してトポケミカルな見地から考察した。（7頁）

The optical and magnetic properties of Ni+-implanted silica.

磯部徹彦，S.Y. Park，R.A. Weeks，R.A. Zuhr

J. Non-Cryst. Solids 189   173-180 1995.08

Research paper (scientific journal), Joint Work, Accepted

　View Summary

Ni+イオンを注入したシリカガラスの光学的・磁気的性質を報告した。（8頁）

Preparation and properties of CdS thin films comprising nano-particles by a solution growth technique.

劉一，磯部徹彦，仙名保

Mater. Res. Bull. 30   975-980 1995.06

Research paper (scientific journal), Joint Work, Accepted

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CdS微粒子から成る薄膜を溶液成長法から生成する方法と、その膜の性質を報告した。（6頁）

Mechanochemical synthesis of non-crystalline ZrTiO4 precursor from inhomogeneous mixed gels.

岡本裕，磯部徹彦，仙名保

J. Non-Crystal. Solids 180   171-179 1995.01

Research paper (scientific journal), Joint Work, Accepted

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非晶質ZrTiO4前駆体を不均一混合ゲルからメカノケミカル合成することを報告した。（9頁）

Mechanochemical synthesis of non-crystalline ZrTiO4 precursor from inhomogeneous gels.

磯部徹彦，岡本裕，仙名保

Better Ceramics Through Chemistry VI. (MRS, 1994 MRS spring Meeting, San Fransisco), Mat. Res. Soc. Symp. Proc. 346   273-277 1994.09

Research paper (international conference proceedings), Joint Work, Accepted

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不均一ゲルから非晶質ZrTiO4前駆体をメカノケミカル合成することを報告した。（5頁）

Effects of ultraviolet irradiation and corona discharge on the crystallization from NiO/SiO2 mixed gels.

磯部徹彦，大村聡，仙名保

J. Non-Cryst. Solids 179   367-371 1994.07

Research paper (scientific journal), Joint Work, Accepted

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NiO/SiO2 混合ゲルから結晶化における紫外線およびコロナ放電の効果を報告した。（5頁）

Homogenization and particle size reduction of PbTiO3 by ball-milling of precursor gels

竹内勝彦，磯部徹彦，仙名保

J. Solid State Chem. 109   401-405 1994.04

Research paper (scientific journal), Joint Work, Accepted

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前駆体ゲルをボールミル摩砕処理することによって、その後の加熱によって生成するPbTiO3が均一化し、粒径が低下することを報告した。（5頁）

Comparison of mechanical complexation and thermal behaviour of metal, oxide and hydrogel mixtures of the Al-Ti-O system.

小島優美， 磯部徹彦，仙名保，M.S. El-Eskandarany，隅山兼治，鈴木謙爾

Int. J. Mechanochem. Mech. Alloy. 1 ( 1 ) 32-41 1994.01

Research paper (scientific journal), Joint Work, Accepted

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Al-Ti-O系の金属、酸化物、含水ゲル混合物のメカニカル複合化とその後の加熱挙動を比較した。（10頁）

Effect of preliminary mechanical treatment on the microhomogenization during heating of hydrous gels as precursors for lead titanate.

小松原悟，磯部徹彦，仙名保

J. Am. Ceram. Soc. 77 ( 1 ) 278-282 1994.01

Research paper (scientific journal), Joint Work, Accepted

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チタン酸鉛前駆体含水ゲルの加熱によるミクロ組成の均一化におけるメカニカル前処理の効果を報告した。（5頁）

Formation of complex oxides under mehanical stress.

廖捷凡，磯部徹彦，仙名保

Proc. 4th Japan-Russia Symp. Mechanochem., (Soc. Powder Tech. Jpn., Nagoya, 1992)    117-124 1993.12

Research paper (international conference proceedings), Joint Work

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メカニカルストレス下での複合酸化物の生成プロセスを報告した。（8頁）

The effects of the homogeneity of non-crystalline Pb-Ti-O gels on the complex thermal processes leading to PbTiO3 formation.

磯部徹彦，小松原悟，仙名保

J. Non-Cryst. Solids 150   144-147 1992.12

Research paper (scientific journal), Joint Work, Accepted

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Pb-Ti-O非晶質ゲルの均一性が加熱によるPbTiO3生成プロセスに与える影響を報告した。（4頁）

Microscopic phase transformation　－crystallization from non-crystalline hydrogels through mechanical stressing－

磯部徹彦，仙名保

Proc. Int. Symp. Mechanical Alloying, Mater. Sci. Forum 88-90   745-752 1992.05

Research paper (international conference proceedings), Joint Work

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メカニカルストレスによって非晶質水和ゲルが結晶化するという微視的相転移を報告した。（8頁）

Change in the dehydration and crystallization of inorganic gels due to mechanical activation.

磯部徹彦，仙名保

Proc. 3rd Japan-Soviet Symp. Mechanochem.; Sib. J. Chem., Ser. Chem. Sci, 5, Oct, 1991, (Academy of Sciences USSR, Sib. Branch, Novosibirsk, 1991)    25-31. 1991.10

Research paper (international conference proceedings), Joint Work

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メカノケミカル活性化による無機物ゲルの脱水と結晶化過程の変化を報告した。（7頁）

Pb-Ti-O系複合ゲルの加熱によるミクロ組成の均一化に及ぼす履歴の影響

磯部徹彦，小松原悟，仙名保

日本化学会誌    1361-1363 1991.10

Research paper (scientific journal), Joint Work, Accepted

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履歴の異なるPbTiO3前駆体ゲルのミクロ組成の均一化に関して報告した。（3頁）

Effects of mechanical activation of inorganic gels on their thermal behavior. 2. Comparison of structure and thermal behavior between zirconia and titania gels.

磯部徹彦，仙名保

J. Solid State Chem. 93   368-377 1991.08

Research paper (scientific journal), Joint Work, Accepted

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メカノケミカル活性化したジルコニアゲルとチタニアゲルの構造と加熱挙動の相違を報告した。（10頁）

Effects of mechanical activation of inorganic gels on their thermal behavior. 1. Crystallization process of titania gels.

磯部徹彦，仙名保

J. Solid State Chem. 93   358-367 1991.08

Research paper (scientific journal), Joint Work, Accepted

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加熱によるチタニアゲルの結晶化プロセスに関して、メカノケミカル活性化の影響を報告した。（10頁）

Preparation of Pb-Ti or Pb-Zr complex oxides with controlled microstructure.

磯部徹彦，小松原悟，仙名保

Proc. 2nd Congr. Particle Technol. Part IV，(Soc. Powder Tech. Jpn, Kyoto, 1990)    370-377 1990.09

Research paper (international conference proceedings), Joint Work

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微細構造を制御してPb-TiおよびPb-Zr複合酸化物を合成することを報告した。（8頁）

Control of litharge-massicot transformation by doping and mechanical activation.

磯部徹彦，仙名保

React. Solids 8   29-40 1990.01

Research paper (scientific journal), Joint Work, Accepted

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リサージとマシコットとの間の相転移をドーピングおよびメカノケミカル活性化によって制御することを報告した。（12頁）

Differences in thermal and mechanochemical polymophism　－ effects of impurity on the system aragonite-calcite －.

磯部徹彦，仙名保

Proc. 2nd Japan-Soviet Symp. Mechanochem. (Soc. Powder. Tech. Jpn., Tokyo, 1988)    161-170 1989.03

Research paper (international conference proceedings), Joint Work

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アラゴナイトとカルサイトとの間の加熱およびメカノケミカル相転移に対する添加物の効果の差違を報告した。（10頁）

Differences in thermal and mechanochemical polymophism－ effects of impurity on the system aragonite-calcite －.

磯部徹彦，仙名保

J. Chem. Soc. Faraday Trans. 1 84 ( 4 ) 1199-1209 1988.04

Research paper (scientific journal), Joint Work, Accepted

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加熱および摩砕による炭酸カルシウムのアラゴナイトからカルサイトへの相転移について、添加物イオン（Pb2+, Sr2+）の影響の相違を報告した。（11頁）