Faculty Profiles - TODA Kenji

Papers - TODA Kenji

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Luminescence Properties of Y(P,V)O-4 Synthesized by Microwave Heating Reviewed

Ayano Toda, Kenji Toda, Tadashi Ishigaki, Kazuyuki Uematsu, Mineo Sato

ASIAN CERAMIC SCIENCE FOR ELECTRONICS III AND ELECTROCERAMICS IN JAPAN XII 421-422 356 - + 2010

Language：English Publishing type：Research paper (international conference proceedings) Publisher：TRANS TECH PUBLICATIONS LTD

Eu3+ doped and undoped Y(P,V)O-4 phosphors were prepared using multi-mode and single-mode microwave oven operated at 2.45 GHz. In the case of the microwave heating method, the phosphor particles were non-aggregated. A homogeneous distribution of Eu ion was observed in the microwave synthesis. No sintering behavior found in the microwave heating may be attributed to a quite shorter heating time. The Eu3+ doped sample synthesized by microwave heating showed intense red emission under UV excitation.

DOI： 10.4028/www.scientific.net/KEM.421-422.356

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Synthesis and luminescence properties of non-doped long persistent phosphors : Mg2SnO4 Reviewed

Akiko Torisaka, Hiroaki Kaneko, Kentaro Nomizu, Sho Abe, Tadashi Ishigaki, Kenji Toda, Kazuyoshi Uematsu, Mineo Sato

ASIAN CERAMIC SCIENCE FOR ELECTRONICS III AND ELECTROCERAMICS IN JAPAN XII 421-422 352 - + 2010

Language：English Publishing type：Research paper (international conference proceedings) Publisher：TRANS TECH PUBLICATIONS LTD

A white long persistence phosphor was synthesized in a single-phase of Mg2SnO4 which was synthesized by a solid-state reaction. This phosphor crystallized in an inverse spinel structure and showed a broad-band emission from 350nm to 700nm. The afterglow was observed upon the excitation by 254nm. A Li-doped Mg2SnO4 sample showed a higher photoluminescence intensity and a longer lifetime than the non-doped one.

DOI： 10.4028/www.scientific.net/KEM.421-422.352

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Photocatalytic Activity of Bismuth Layered Perovskite Treated with Acid Reviewed

Soihiro Watanabe, Yousuke Narumi, Kenji Toda, Tadashi Ihigaki, Kazuyoshi Uematsu, Mineo Sato

ASIAN CERAMIC SCIENCE FOR ELECTRONICS III AND ELECTROCERAMICS IN JAPAN XII 421-422 554 - + 2010

Language：English Publishing type：Research paper (international conference proceedings) Publisher：TRANS TECH PUBLICATIONS LTD

We synthesized Sr0.7La0.2[ ](0.1)Bi2Ta2O9 (SBTL, [ ] vacancy), and measured their photocatalytic activity for water decomposition under UV light irradiation after acid treatment. They showed the high photocatalytic activity under UV light irradiation (H-2 evolution (213 mu mol / h), O-2 evolution (82 mu mol / h)).

DOI： 10.4028/www.scientific.net/KEM.421-422.554

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Novel Ba-Sc-Si-oxide and oxynitride phosphors for white LED Reviewed

Tomoyuki Nakano, Yoshitaka Kawakami, Kazuyoshi Uematsu, Tadashi Ishigaki, Kenji Toda, Mineo Sato

JOURNAL OF LUMINESCENCE 129 ( 12 ) 1654 - 1657 2009.12

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

Alkaline earth silicates. which comprise a host material doped with rare-earth minerals, show excellent luminescence properties with various crystal structures and high stability. From results of this study, we report luminescence properties of Ba(9)Sc(2)Si(6)O(24):Eu(2+) and Ba(9)Sc(2+delta)Si(6)O(24+3 delta)N(3 delta):Eu(2+) as a novel alkaline earth silicate and silicon oxynitride phosphors for white LEDs Using a conventional solid-state reaction, Ba(9)Sc(2)Si(6)O(24):Eu(2+) samples were synthesized and Ba(9)Sc(2+delta)Si(6)O(24+3 delta)N(3 delta):Eu(2+) samples were obtained by nutrization of Ba(9)Sc(2+delta)Si(6)O(24):Eu(2+) The samples can be excited by blue light, exhibiting green (Ba(9)Sc(2)Si(6)O(24):Eu(2+)) and yellow (Ba(9)Sc(2+delta)Si(6)O(24+3 delta)N(3 delta):Eu(2+)) efficiently, which are emissions for use in white LEDs essentially. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jlumin.2009.04.028

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Structure and luminescence of sodium and lanthanide(III) coordination polymers with pyridine-2,6-dicarboxylic acid Reviewed

Taoyun Zhu, Kazuya Ikarashi, Tadashi Ishigaki, Kazuyoshi Uematsu, Kenji Toda, Hirokazu Okawa, Mineo Sato

INORGANICA CHIMICA ACTA 362 ( 10 ) 3407 - 3414 2009.8

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE SA

A series of coordination polymers constructed by sodium, lanthanide(III), and pyridine-2,6-dicarboxylate (dipic),NaLn(dipic)(2) center dot 7H(2)O (Ln = Eu, Gd, Tb), have been prepared under a hydrothermal condition. The crystal structures of the three compounds which are isostructual were determined by single-crystal X-ray diffraction. The two-dimensional layers found in the compounds are built up from six-folded {NaO(6)} polyhedra and nine-folded {LnN(2)O(7)} polyhedra, these being edge-shared each other along the c axis and bridged by carboxylate groups of dipic along the b axis, respectively. This two-dimensional framework provides cavities inside the layer and interlayer spaces outside the layer for accommodation of the two dipic molecules coordinated to a lanthanide(III) ions. The dehydrated materials obtained by heating the as-synthesized crystals at 200 degrees C held their crystal structure, and absorbed the same amounts of water molecules as those of the as-synthesized crystals upon the exposure of 100% relative humidity at room temperature. The Eu and Tb compounds showed strong red and green emissions, respectively, due to an energy transfer from dipic molecules to trivalent emission ions. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.ica.2009.01.036

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One-dimensional coordination polymers of praseodymium(III)-vanadium(V) complexes with pyridine-2,6-dicarboxylic acid Reviewed

Taoyun Zhu, Koichi Murokawa, Kazuyoshi Uematsu, Tadashi Ishigaki, Kenji Toda, Hirokazu Okawa, Mineo Sato

POLYHEDRON 28 ( 11 ) 2196 - 2200 2009.7

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

This paper represents the hydrothermal synthesis of new isomorphous lanthanide-vanadium complexes with one-dimensional coordination polymers: [Pr(2)(VO(2))(2)(dipic)(4)(H(2)O)(9)] center dot nH(2)O with dipic = pyridine-2,6-dicarboxylic acid and n = 7.75. The structure determination shows a unique one-dimensional structure in which three types of chains run along the c-axis: the chain of positively charged praseodymium complexes bridged by a dipic ligand ([Pr(dipic)(H(2)O)5](+)), the chain of negatively charged, stacked vanadium complexes ([VO(2)(dipic)](-)), and the chain of neutral praseodymium complexes with a bridged dipic ligand and a coordinating dipic ligand ([Pr(dipic)[VO(2)(dipic)](H(2)O)(4)]). Such one-dimensional chains provide open channels which can accommodate water molecules. Not only accommodated water molecules but also ones coordinated to praseodymium ions were easily removed and absorbed upon heating at 200 degrees C and exposure of humidity at room temperature, respectively. (C) 2009 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.poly.2009.01.010

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Low Temperature Synthesis of TiO2 from Acid Solution Reviewed

S. Watanabe, S. Nkajima, K. Uematsu, T. Ishigaki, K. Toda, M. Sato

Key Engineering Materials 421-422 498 - 501 2009.7

New Titanium Oxide Compound for Photocatalytic Water Splitting, Hydrous Na16Ti10O28 Reviewed

S. Nakajima, S. Watanabe, K. Uematsu, T. Ishigaki, K. Toda, M. Sato

Key Engineering Materials 421-422 546 - 549 2009.7

One-dimensional channels constructed from hydrogen bonding networks among 4,4 '-bipyridine units and water molecules available for accommodation of polyoxomolybdate clusters Reviewed

Hidekazu Kobayashi, Kazuya Ikarashi, Kazuyoshi Uematsu, Kenji Toda, Hirokazu Okawa, Zhu Taoyun, Mineo Sato

INORGANICA CHIMICA ACTA 362 ( 1 ) 238 - 242 2009.1

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE SA

A hybrid coordination complex, [(H(5)O(2))(H(2)bpy)(bpy)(4)][NaMo(8)O(26)]center dot 2H(2)O (bpy = 4,4-bipyridine), was synthesized via hydrothermal reactions at 150 degrees C. The structure consists of two moieties; one is an infinite chain of beta-[Mo(8)O(26)] clusters, each of which is inter-linked up by a sodium ion, and the other a two-dimensional network constructed from doubly protonated bpy ions and its neutral molecules, which are linked with water molecules by hydrogen bonds. The stacking of the networks provides one-dimensional tunnels suitable for Na-beta-[Mo(8)O(26)] chains. (c) 2007 Published by Elsevier B.V.

DOI： 10.1016/j.ica.2007.07.040

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Metastable Sr0.5TaO3 Perovskite Oxides Prepared by Nanosheet Processing Reviewed

Keigo Inaba, Shinya Suzuki, Yuji Noguchi, Masaru Miyayama, Kenji Toda, Mineo Sato

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY 2008 ( 35 ) 5471 - 5475 2008.12

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-BLACKWELL

Metastable Sr0.5TaO3 with a perovskite structure was prepared by using layer-structured H2Sr1.5Ta3O10 by two different processes: direct dehydration and nanosheet processing, and the photocatalylic activities of the obtained structures were investigated for the evolution of H-2 and O-2 from distilled water under UV light irradiation. The average gas evolution rates were 66 mu mol h(-1) (H-2) and 1.6 mu mol h(-1) (O-2) for Sr0.5TaO3 prepared by direct dehydration, whereas those obtained by nanosheet processing were 1.26 mu mol h(-1) (H-2) and 33 mu mol h(-1) (O-2). It was shown that nanosheet processing is effective for obtaining metastable Sr0.5TaO3 with high photocatalytic activities. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

DOI： 10.1002/ejic.200800776

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Morphology Cntrol of High Luminance Phosphors

K. Toda, M. Hosoume, K. Sato, K. Uematsu, M. Sato, A. watanabe, T. Fukui

Key Engineering Materilas 388 107 - 110 2008.7

Melt synthesis of oxide phosphors with K(2)NiF(4) structures: CaLa(1-x)Eu(x)GaO(4)

Tadashi Ishigaki, Kenji Toda, Tomoaki Watanabe, Naonori Sakamoto, Nobuhiro Matsushita, Masahiro Yoshimura

JOURNAL OF MATERIALS SCIENCE 43 ( 14 ) 4749 - 4752 2008.7

Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER

In order to synthesize compounds of various Perovskite-related structures, we have utilized a novel "melt synthesis technique" for phosphors rather than the conventional solid state reaction techniques. The solid state reactions require multi-step processes of heating/cooling with intermediate grindings to make homogeneous samples. However, for the melt synthesis, it is possible to make a homogeneous sample in a single step within a short period of time (1-60 s) due to the liquid phase reaction in the molten samples, which were melted by strong light radiation in an imaging furnace. In this study, we have prepared a red-phosphor CaLaGaO(4):Eu(3+) which has a perovskite-related layered K(2)NiF(4) structure. Well-crystallized CaLa(1-x) Eu (x) GaO(4) samples with the K(2)NiF(4) structure have been obtained up to x = 0.25, but there was the formation of an olivine phase when x = 0.5-1.0. The red emission at 618 nm increased with the increasing value of x up to x = 0.25.

DOI： 10.1007/s10853-008-2481-9

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Synthesis and Luminescence Property of Blue Phosphor, BaMgAl10O17:Eu2+, by the Flash-Creation-Method

WATANABE Akira, FUKUI Takehisa, NOGI Kiyoshi, TODA Kenji, KAWADA Satoshi, SHIRAKURA Shigeki, HOSOUME Masafumi, UEMATSU Kazuyoshi, SATO Mineo

Journal of High Temperature Society Vol.34 ( 3 ) 130 - 135 2008.5

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：High Temperature Society of Japan

BaMgAl10O17:Eu2+ is a promising blue phosphor for lump, CRT and PDP. Conventionally, the BAM phosphors synthesize by the solid-state reaction from the mixture of oxide or carbonate starting materials. The solid-state reaction needs high temperature to get well-crystallized single phase. However, the control of particle morphology and size distribution is difficult for such a high temperature synthesis. In this study, we reported new synthetic technique using flash creation method derived nanopowder precursor. In the new technique, well-crystallized single phase phosphors were obtained at 1400°C for 6h. Although the powders were grown into the plate-like particles, the BAM powders retain the nano-size morphology after annealing. The emission intensity under UV excitation of Ba0.9Eu0.1MgAl10O17 from the FCM-derived nanopowder was 110% compared with phosphors prepared by the conventional solid-state reaction. The excitation intensity under VUV (146nm) of the FCM derived nanopowder was 159% of the conventional solid-state reaction.

DOI： 10.7791/jhts.34.130

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Reinvestigation of layered poly[aqua-sodium(I) [[aquasamarium(III)]-di-mu-aqua-mu(3)-pyridine-2,6-dicarboxylato-mu(2)-pyridine-2,6-dicarboxylato] trihydrate]

Kazuya Ikarashi, Taoyun Zhu, Kazuyoshi Uematsu, Kenji Toda, Mineo Sato

ACTA CRYSTALLOGRAPHICA SECTION E-STRUCTURE REPORTS ONLINE 63 ( 8 ) M2203 - U1635 2007.8

Language：English Publishing type：Research paper (scientific journal) Publisher：BLACKWELL PUBLISHING

The crystal structure of the title compound, {[NaSm(C7H3- NO4)(2)(H2O)(4)]center dot 3H(2)O}(n), was first reported by van Albada, Gorter & Reedijk [(1999), Polyhedron, 18, 1821-1824]. It has now been reinvestigated and confirmed from single-crystal data, giving greater understanding of the role of the water molecules. The two-dimensional layers found in the compound are built up from six-coordinate NaO6 polyhedra and nine-coordinate SmN2O7 polyhedra. The former share edges with each other along the c axis and the latter are bridged by carboxylate groups of pyridine-2,6-dicarboxylate anions along the b axis. Eight-membered rings of water molecules, connected to one another by hydrogen bonding, are formed in the interlayer spaces.

DOI： 10.1107/S160053680702884X

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Lanthanum-indium oxysulfide as a visible light driven photocatalyst for water splitting Reviewed

Kiyonori Ogisu, Akio Ishikawa, Kentaro Teramura, Kenji Toda, Michikazu Hara, Kazunari Domen

CHEMISTRY LETTERS 36 ( 7 ) 854 - 855 2007.7

Language：English Publishing type：Research paper (scientific journal) Publisher：CHEMICAL SOC JAPAN

La-In-based oxysulfide is demonstrated to act as a photocatalyst for the reduction of H+ to H-2 and the oxidation of H2O to O-2 in the presence of sacrificial reagents under visible light (420 < A < 480 nm). Loading with IrO2 is effective for promoting O-2 evolution, while Pt is effective as a cocatalyst for H-2 evolution.

DOI： 10.1246/cl.2007.854

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Solid Chemical Reaction by Microwave Heating for the Synthesis of LiFePO4 Cathode Material Reviewed

K.. Uematsu, A. Ochiai, K. Toda, M. Sato

Journal of Ceramic Society of Japan 115 ( 7 ) 450 - 454 2007.7

Superconductivity of Layered Perovskite Synthesized by Soft Chemistry Reviewed

T. Teranishi, S. Takezawa, K. Toda, H. Ishikawa, K. sato, K. Uematsu, M. Sato

Key Engineering Materials 350 163 - 166 2007.6

Electrochemical performance of Al-doped LiMn2O4 prepared by different methods in solid-state reaction Reviewed

Teruaki Kakuda, Kazuyoshi Uematsu, Kenji Toda, Mineo Sato

JOURNAL OF POWER SOURCES 167 ( 2 ) 499 - 503 2007.5

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

Al-doped LiMn2O4 cathode materials synthesized by a newly developed wet-milling method and a dry process method using a conventional solid-state reaction were evaluated physicochemically and electrochemically. In the wet-milling method, a precursor was made from the raw materials atomized by a wet milling. A good cyclic performance was obtained for the LiMn2O4 samples prepared by the wet-milling method, achieved up to 99% of retention of capacity at 50 degrees C at the 30th cycle. The precursor obtained by the wet-milling method was well homogenous and highly reactive due to their finely ground particles, giving good crystallinity to LiMn2O4 products. (C) 2007 Published by Elsevier B.V.

DOI： 10.1016/j.jpowsour.2007.01.035

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Synthesis of Blue Phosphor, BaMgAl10O17: Eu2+, from the Flash Creation Method Derived Nanopowder Reviewed

A. Watanabe, T. Fukui, Y. Ito, M. Hosoume, S. Shirakura, S. Kawada, K. Toda, K. Uematsu, M. Sato

ITE LETTERS 8 ( 1 ) 38 - 41 2007.2

透光性酸化イットリウム(Y2O3)焼結体の作製 Reviewed

齋藤紀子, 渡邊良二, 瀬山博之, 戸田健司, 大滝浩通, 堀田憲康

Journal of the Materials Science Society of Japan 44 ( 1 ) 272 - 277 2007.2

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Papers - TODA Kenji