Faculty Profiles - TODA Kenji

Papers - TODA Kenji

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Combinatorial synthesis of phosphors（共著） Reviewed

T. Ishigaki, K. Toda, M. Yoshimura, K. Uematsu, M. Sato

Science and Technology of Advanced Materials 12 054205 2011.11

A new raw material SiO for the synthesis of silicate phosphors Reviewed

K. Toda

Journal of Ceramic Processing Research 12 ( 3 ) s256 - s258 2011.11

Synthesis of CaMgGe2O6:Mn2+ phosphors for field emission lamps （共著） Reviewed

S. Sato, K. Uematsu, T. Ishigaki, K.Toda, M. Sato, H. Sasaoka, M. Ooka, K. Nishimura

Journal of Ceramic Processing Research 12 ( 3 ) s278 - s281 2011.11

Synthesis of Mn4+ doped red emitting phosphor for white LEDs（共著） Reviewed

K. Seki, K. Uematsu, T. Ishigaki, K. Toda, M. Sato

Journal of Ceramic Processing Research 12 ( 3 ) s286 - s288 2011.11

Synthesis of Ba2SiO4:Eu2+ by a gas-solid phase method （共著） Reviewed

T. Sakamoto, K. Uematsu, T. Ishigaki, K. Toda, M. Sato

Journal of Ceramic Processing Research 12 ( 3 ) s272 - s274 2011.11

New rare earth-free red emitting phosphor SiP2O7:Mn2+ and 4+ Under UV light excitation（共著） Reviewed

M. Maeda, K. Uematsu, T. Ishigaki, K. Toda, M. Sato

Journal of Ceramic Processing Research 12 ( 3 ) s263 - s266 2011.11

Crystal Growth of Silicate Phosphors from the Vapor Phase Invited Reviewed

Tadashi Ishigaki, Kenji Toda, Tatsuya Sakamoto, Kazuyoshi Uematsu, Mineo Satot

IEICE TRANSACTIONS ON ELECTRONICS E94C ( 11 ) 1745 - 1748 2011.11

Language：English Publishing type：Research paper (scientific journal) Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

Well-crystallized Ba2SiO4:Eu2+ powders were grown on a substrate by the vapor phase reaction between a mixed powder (barium carbonate and europium oxide) and SiO gas. The vaporization of SiO occurs at 1400-1600 degrees C from the SiO2 source (or SiO powder) in a reducing atmosphere. The formed SiO gas was transported by 95 vol% Ar - 5 vol% H-2 gas and reacted with the raw material powders. The emission intensity of the Ba2SiO4:Eu2+ phosphor synthesized by the new vapor phase technique is about 2.6 times higher than that of a conventional solid-state reaction sample.

DOI： 10.1587/transele.E94.C.1745

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A new yellowish green NaAl(SiO4):Eu2+ phosphor for UV-LED using a liquid phase precursor process（共著） Reviewed

D. S. Jo, K. H. Choi, K. Toda, T. Masaki, D. H. Yoon

Jornal of Ceramic Processing Research 12 ( 1 ) s47 - s50 2011.3

Synthesis and properties of Na3YSi2O7:Eu3+ phosphor for fluorescent lamp Reviewed

T. Sakamoto, S. Kousaka, K. Uematsu, T. Ishigaki, K. Toda, M. Sato

PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 8, NO 9 8 ( 9 ) 2731 - 2734 2011

Language：English Publishing type：Research paper (international conference proceedings) Publisher：WILEY-V C H VERLAG GMBH

Eu3+ doped Na3YSi2O7 phosphors were prepared by a solid state reaction. It was found that the excitation spectra included two regions: i.e. the broad excitation band at 237 nm and narrow peaks at 395 nm and 463 nm. The peak located at 237 nm was assigned to the combination of the charge transfer transition of O-Eu, while the peaks at 395 nm and 463 nm were assigned to the f-f transitions of Eu3+. The emission spectrum was dominated by the red peak located at 612 nm due to the electric dipole transition of D-5(0)-F-7(2). The Eu3+ doped Na3YSi2O7 phosphor was suitable for use in fluorescent lamps and white LED applications. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

DOI： 10.1002/pssc.201084125

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Synthesis of Eu2+-doped A-site and oxygen-deficient perovskite related host for photoluminescent materials Reviewed

Tadashi Ishigaki, Tomoki Hatsumori, Tatsuya Sakamoto, Kazuyoshi Uematsu, Kenji Toda, Mineo Sato

PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 8, NO 9 8 ( 9 ) 2728 - 2730 2011

Language：English Publishing type：Research paper (international conference proceedings) Publisher：WILEY-V C H VERLAG GMBH

Perovskite-related compounds have been investigated in many fields, because they have various unique properties due to their compositions and structures which are characterized by various combinations of the A and B cations. In addition, defect perovskite-type compounds have also been investigated in many areas, especially as ion conductors. In this study, we used the A-site and oxygen-deficient perovskite, Sr3Al2O6, as a photoluminescent host material. This means that the defect sites were able to substitute several ions. We investigated the A(3)Al(2)O(6):Eu2+ phosphor material (A = Mg, Ca, Sr, Ba) produced by a solid state reaction in several kinds of atmospheres. Based on our results, the phosphor showed wide excitation and emission bands of 300-400 nm and 450-600 nm, respectively. The emission color control depended on the A-site substitution ratio. It is a very useful phosphor for white LEDs. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

DOI： 10.1002/pssc.201084140

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Development of gas-solid phase hybrid synthesis method of single crystal Ba2SiO4:Eu2+ Reviewed

Tatsuya Sakamoto, Kazuyoshi Uematsu, Tadashi Ishigaki, Kenji Toda, Mineo Sato

ELECTROCERAMICS IN JAPAN XIV 485 325 - + 2011

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

We succeeded in the single crystal growth of Ba2SiO4:Eu2+ by novel synthesis method which was gas (SiO) and solid (Ba - Sc - Al - Eu - 0) phase hybridized. The Ba2SiO4:Eu2+ single crystal was synthesized by interfacial crystal growth after the reaction of the SiO gas with the surface of Ba - Sc - Al - Eu - O substrate in the reductive atmosphere. The single crystals were plate-like crystals with about 500 mu m sizes and emitted green light around 500 nm under 300 - 450 nm excitation.

DOI： 10.4028/www.scientific.net/KEM.485.325

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Synthesis of anataseTiO(2) having high specific surface area from a gel precursor Reviewed

Keiko Fukushi, Sae Nakajima, Kazuyoshi Uematsu, Tadashi Ishigaki, Kenji Toda, Mineo Sato

ELECTROCERAMICS IN JAPAN XIV 485 279 - + 2011

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

Anatase TiO2 having high temperature stability and specific surface area was synthesized using a gel precursor in very mild conditions. The precursor gel was obtained by dialysis treatment of Na16Ti10O28-HNO3 solution. The samples were characterized by X-ray diffraction analysis, transmission electronmicroscopy, Brunner-Emmett-Teller method for specific surface area measurements, and thermogravimetric analysis.

DOI： 10.4028/www.scientific.net/KEM.485.279

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Microwave synthesis technique for long phosphorescence phosphor SrAl2O4:Eu2+, Dy3+ using carbon reduction Reviewed

Tadashi Ishigaki, Hitomi Mizushina, Kazuyoshi Uematsu, Nobuhiro Matsushita, Masahiro Yoshimura, Kenji Toda, Mineo Sato

MATERIALS SCIENCE AND ENGINEERING B-ADVANCED FUNCTIONAL SOLID-STATE MATERIALS 173 ( 1-3 ) 109 - 112 2010.10

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

As described herein, we prepared SrAl2O4:Eu2+, Dy3+ phosphor using a domestic microwave oven operated at 2.45 GHz with 500 Win 30 min, processes with carbon reduction. Using carbon as the microwave absorber it generates thermal energy. Furthermore, heating with carbon can provide a reductive atmosphere. Prepared samples emitted phosphorescence emission for a long time. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.mseb.2009.11.004

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Synthesis and luminescence property of new phosphate phosphor, RbPO3:Tb Reviewed

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

MATERIALS SCIENCE AND ENGINEERING B-ADVANCED FUNCTIONAL SOLID-STATE MATERIALS 173 ( 1-3 ) 168 - 170 2010.10

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

Luminescence property of a new phosphate phosphor, RbPO3:Tb, is reported in this paper. A single phase sample was obtained by thermal decomposition of a raw material mixture (RbH2PO4 and Tb4O7) at 973 K. The phosphor could be efficiently exited by the UV light, yielding an intense green emission around 550 nm. The intense green emission is originated from the f-f transition of Tb3+ ion. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.mseb.2009.12.025

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Synthesis and characterization of low-dimensional structure Reviewed

M. Nishiya, K. Uematsu, T. Ishigaki, K. Toda, M. Sato

Key Engineering Materials 445 191 - 194 2010.6

Morphology control of phosphors synthesized by microwave heating method Reviewed

A. Toda, K. Uematsu, T. Ishigaki, K. Toda, M. Sato

Key Engineering Materials 445 233 - 236 2010.6

Low temperature synthesis method of La2O2S2 and evaluation of the photocatalytic activity Reviewed

M. Ohashi, T. Ishigaki, K. Uematsu, K. Toda, M. Sato

Key Engineering Materials 445 217 - 220 2010.6

Melt synthesis of Eu-doped oxide phosphors using arc-imaging furnace Reviewed

Tadashi Ishigaki, Masahiro Yoshimura, Nobuhiro Matsushita, Kazuyoshi Uematsu, Kenji Toda, Mineo Sato

JOURNAL OF THE EUROPEAN CERAMIC SOCIETY 30 ( 2 ) 165 - 169 2010.1

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCI LTD

To synthesize various complex oxide materials and their solid solutions, we applied a novel "melt-synthesis technique" rather than conventional solid-state reaction techniques. Rapid synthesis methods to develop those double oxides have been strongly anticipated. During melt synthesis, the mixture of oxides or their precursors is melted rapidly (1-60 s) in an arc-imaging furnace using strong light radiation. A spherical molten sample with multiple homogeneously mixed cations was solidified directly on a copper hearth with rapid cooling of ca. 10(2) degrees C/s.
We studied the synthesis of A(2)BO(4) type double oxides (AA')(2)BO(4) (A= Sr(2+), Ca(2+), A' = La(3+), Gd(3+), Y(3+), Eu(3+), B=Al) using this method. Homogeneous samples with Eu(3+) dopants were synthesized using liquid phase mixing in a few seconds, which is much faster than diffusions of ions in solid phase. Red fluorescence under the irradiation of ultraviolet light (254 and 365 nm) was observed. The excitation band shifted. (C) 2009 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jeurceramsoc.2009.05.040

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Synthesis and Characterization of CaZnGe2O6 Reviewed

Hirotoshi Hatakeyama, Yousuke Narumi, Kazuyoshi Uematsu, Tadashi Ishigaki, Kenji Toda, Mineo Sato

ELECTROCERAMICS IN JAPAN XIII 445 187 - + 2010

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

We report the synthesis and photocatalytic activity of CaZnGe2O6, which contains Ca2+ ions and one-dimensional GeO4 chains (Ge4+: d(10) electronic configuration). This sample demonstrated the water splitting phenomenon by loading with RuO2 cocatalysis. Moreover, Ln-doped CaZnGe2O6 (where Ln = La, Ce, Pr, Nd, or Sm) shows a higher photocatalytic activity than CaZnGe2O6.

DOI： 10.4028/www.scientific.net/KEM.445.187

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Development of New Red Phosphor Na3YSi2O7:Eu3+ for a white LED Reviewed

Shinichiro Kousaka, Kenji Toda, Tadashi Ishigaki, Kazuyoshi Uematsu, Mineo Sato

ASIAN CERAMIC SCIENCE FOR ELECTRONICS III AND ELECTROCERAMICS IN JAPAN XII 421-422 360 - + 2010

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

New red phosphors Na3YSi2O7:Eu3+ was prepared by a conventional solid-state reaction. This silicate phosphor can be efficiently excited by near UV light, yielding an intense red emission. Under the excitation of near UV light, the emission intensity is higher than that of a commercial red phosphor Y2O2S:Eu3+.

DOI： 10.4028/www.scientific.net/KEM.421-422.360

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Papers - TODA Kenji