Faculty Profiles - TODA Kenji

Papers - TODA Kenji

Division display 201 - 220 of about 225 ／ All the affair displays >>

Structure refinement of lithium ion conductors Li3Sc2(PO4)(3) and Li3-2x(Sc1-xMx)(2)(PO4)(3) (M = Ti, Zr) with x = 0.10 by neutron diffraction Reviewed

T Suzuki, K Yoshida, K Uematsu, T Kodama, K Toda, ZG Ye, M Ohashi, M Sato

SOLID STATE IONICS 113 89 - 96 1998.12

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

The crystal structure of lithium ion conductors, Li3Sc2(PO4)(3) and Li3-2x(Sc1-xMx)(2)(PO4)(3) (M = Ti, Zr) with x = 0.10, were refined by Rietveld analysis for neutron diffraction patterns in order to confirm the site location and site occupancy for Li ions. The Rietveld refinement confirmed that a high disorder was introduced to three kinds of Li sites in the high temperature superionic conduction phase of Li3Sc2(PO4)(3). The high temperature phase was stabilized at room temperature by substituting Ti4+ or Zr4+ for Sc3+ sites. The stabilized materials were also found to have similar high disorder over the Li sites. (C) 1998 Published by Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0167-2738(98)00279-3

Lithium intercalation and cathode performance of Li2CrTi (PO4)(3) Reviewed

M Sato, S Hasegawa, K Yoshida, K Toda

DENKI KAGAKU 66 ( 12 ) 1236 - 1240 1998.12

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

Chemical and electrochemical lithium intercalation behavior was investigated on Li2CrTi(PO4)(3). Lithium ions with an almost one mole per formula were inserted by the chemical intercalation by n-butyllithium. The structure refinement was done by the Rietveld method for both parent and intercalated materials. The results showed that both materials crystallized in a lower crystal symmetry, R (3) over bar or C2/c, which is different from that previously reported in the literature. The intercalated material exhibited a cathode performance with a plateau at around 2.8 V vs. Li/Li+ upon charging and 2.4 V vs. Li/Li+ upon discharging.

Structural chemistry of new ion-exchangeable tantalates with layered perovskite structure: New reduced Ruddlesden-Popper phase, Na2Ca2Ta3O10 Reviewed

K Toda, T Teranishi, M Takahashi, ZG Ye, M Sato

SOLID STATE IONICS 113 501 - 508 1998.12

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

A new reduced tantalate, Na2Ca2Ta3O10, with layered perovskite structure was synthesized by an intercalation reaction from the parent sodium compound, NaCa2Ta3O10, The crystal structures of these compounds were determined by the Rietveld analysis of powder X-ray diffraction pattern. Although the framework of the perovskite layer of intercalation compound is analogous to that of the parent compound, the coordination of interlayer sodium ion in the intercalation compound is clearly distinct from that of the parent compound. The sodium ions within the interlayer of intercalation compound have a rock-salt coordination because of a too strong repulsive force fas a tetrahedral coordination. The intercalation compound, Na2Ca2Ta3O10, is the first example of a reduced! tantalate with a Ruddlesden-Popper type structure. (C) 1998 Published by Elsevier Science BN. All rights reserved.

DOI： 10.1016/S0167-2738(98)00316-6

Cathode Characteristics of Lithium Transition Metal Phosphate Synthesized by Ion-exchange Reaction Reviewed

K. Yoshida, K. Toda, K. Uematsu, M. Sato

Key Engineering Materials 157-158 289 - 296 1998.12

Chemical and electrochemical intercalation of lithium into the tantalates with the layered perovskite structure Reviewed

K Toda, M Takahashi, T Teranishi, K Uematsu, M Sato

DENKI KAGAKU 66 ( 12 ) 1241 - 1247 1998.12

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

New reduced tantalates, Li2LaTa2O7 and Li2Ca2Ta3O10, with layered perovskite structure were synthesized by electrochemical or chemical intercalation reaction of lithium from the parent Dion-Jacobson series compounds. The crystal structures of these compounds were determined by the Rietveld analysis of powder X-ray diffraction pattern. The crystal structures of intercalation compounds were analogous to those of the parent compounds. The intercalation of the lithium ion leads to a large contraction along the stacking direction of perovskite layers because of a higher interlayer charge density. These intercalation compounds are the first example of reduced tantalates with layered perovskite structure.

Synthesis, Structure and Properties of the Magnetic Relaxor Ferroelectric Pb(Fe2/3W1/3)O3 [PFW] Reviewed

Z-G. Ye, K. Toda, M. Sato, E. Kita, H. Schmid

Journal of Korean Physical Society 32 1028 - 1031 1998.12

Concentration quenching of the Eu3+-activated luminescence in some layered perovskites with two-dimensional arrangement Reviewed

Toshihiko Honma, Kenji Toda, Zuo-Guang Ye, Mineo Sato

Journal of Physics and Chemistry of Solids 59 ( 8 ) 1187 - 1193 1998

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

The quenching of Eu3+-emission in the layered perovskite compounds SrRE2Al2O7, BaRE2Ti3O10, RETa3O9 and RbRETa2O7 (RE = rare earths) with two-dimensional arrangement of rare earth ions was investigated. The highest luminescence intensity was observed in both tantalum compounds, RETa3O9 and RbRETa2O7. The concentration quenching found in these compounds can be explained by a percolation model with two-dimensional interactions between the Eu3+ sites in the host lattice. The energy transfer between the Eu3+ ions takes place by the multipole-multipole interaction among the nearest-neighbor sites in the rare earth sublattice. © 1998 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0022-3697(98)00056-0

Stabilization of superionic conduction phase in Li3Sc2(PO4)(3) Reviewed

T Suzuki, K Yoshida, K Uematsu, T Kodama, K Toda, ZG Ye, M Sato

SOLID STATE IONICS 104 ( 1-2 ) 27 - 33 1997.12

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

Lithium superion conductors, Li3+2x(Sc1-xMgx)(2)(PO4)(3), Li3-2x(Sc1-xMx)(2)(PO4)(3) (M=Ti, Zr, Sn, Hf) and Li3-4x(Sc1-xMx)(2)(PO4)(3) (M = Nb, Ta) were prepared by a solid-state reaction. TG-DTA analysis indicated no phase transition in Li3+2x(Sc1-xMgx)(2)(PO4)(3) and Li3-2x(Sc1-xMx)(2)(PO4)(2) (M = Ti, Zr, Sn, Kf) with x higher than 0.05, and in Li3-4x(Sc1-xMx)(2)(PO4)(3) (M=Nb, Ta) with x higher than 0.025. The room temperature ionic conductivity of Li3Sc2(PO4)(3) has been increased by three orders of magnitude with the highest conductivity observed in Li3-2x(Sc1-xTix)(2)(PO4)(3) with x = 0.20 and in Li3-2x(Sc1-xZrx)(2)(PO4)(3) with x = 0.10. It was ascribed to the stabilization of the high temperature superionic conduction phase and the introduction of vacancies on the Li+ sites by substituting Ti4+ Or Zr4+ for Sc3+.

DOI： 10.1016/S0167-2738(97)00404-9

Structure determination of new layered perovskite compound, NaLaTa2O7, synthesized by ion-exchange reaction Reviewed

K Toda, K Uematsu, M Sato

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 105 ( 6 ) 482 - 485 1997.6

Language：English Publishing type：Research paper (scientific journal) Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI

A new layered perovskite compound, NaLaTa2O7, was synthesized by ion-exchange reaction of the rubidium compound, RbLaTa2O7. The crystal structure of the compound was determined by the Rietveld analysis for powder X-ray diffraction pattern. The crystal structure is analogous to that of the corresponding niobate compound, NaLaNb2O7. This layered perovskite compound is a new member of the Dion-Jacobson series with n=2 for the general formula M[A(n-1)B(n)O(3n+1)] (M=alkali metals).

DOI： 10.2109/jcersj.105.482

Synthesis and properties of lithium ion conductors Li3-2x(Sc1-xZrx)2(PO4)3 Reviewed

Mineo Sato, Takahito Suzuki, Kenji Yoshida, Kazuyoshi Uematsu, Kenji Toda, Zuo Guang Ye

Journal of Alloys and Compounds 250 ( 1 ) 510 - 514 1997

Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier Science S.A.

Lithium ion conductors, Li3-2x(Sc1-xZrx)2(PO4) (0qqxqq0.3), were prepared by a solid-state reaction. TG-DTA analysis indicated no phase transition in the samples with x superior to 0.05. X-ray powder diffraction analysis of these samples clearly showed the stabilization of a superionic conduction phase at room temperature with an orthorhombic system Pbcn. The highest conductivity was observed for the sample with x = 0.05, and ascribed to the stabilization of the superionic conduction phase and the introduction of vacancies on the Li+ sites by substituting Zr4+ for Sc3+.

DOI： 10.1016/S0925-8388(96)02746-6

Unusual concentration quenching of europium luminescence in new layered perovskite compound, RbLa1-xEuxTa2O7 (0 ≤ x ≤ 1) Reviewed

Kenji Toda, Toshihiko Honma, Mineo Sato

Journal of Luminescence 71 ( 1 ) 71 - 75 1997

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

Dependence of emission intensity on Eu3+ concentration in new layered perovskite compound, RbLa1-xEuxTa2O7, with a perfect two-dimensional arrangement of luminescence center was studied. Critical value for concentration quenching is x = 0.5 for RbLa1-xEuxTa2O7. The critical concentration of this compound is discussed in terms of the crystal structure determined by the powder X-ray diffraction pattern using the Rietveld method. The concentration quenching found in this compound can be explained by means of a percolation model with two-dimensional interactions between Eu3+ sites in the host lattice.

DOI： 10.1016/S0022-2313(96)00097-X

Synthesis and structure determination of new layered perovskite compound, KLaTa2O7 Reviewed

Kenji Toda, Toshihiko Honma, Zuo Guang Ye, Mineo Sato

Journal of Alloys and Compounds 249 ( 1 ) 256 - 259 1997

Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier Science S.A.

A new layered perovskite compound, KLaTa2O7, was synthesized by ion-exchange reaction from the rubidium compound. RbLaTa2O7. The crystal structure of KLaTa2O7 was determined by Rietveld analysis from powder X-ray diffraction patterns. It is analogous to the structure of the corresponding niobate compound. This layered perovskite compound is a new member of the Dion-Jacobson series with n = 2 for the general formula A[Mn-1BnO3n+1] (A = monovalent cations, B = Nb or Ta). The structural features of KLaTa2O7 are discussed by comparison with other compounds of the ALaTa2O7 family and the titanate compounds.

DOI： 10.1016/S0925-8388(96)02752-1

Preparation of high lithium ion conducting LiLnSiO(4) (Ln=La,Sm) thin films by sol-gel method Reviewed

M Sato, H Ueda, Y Ohara, K Uematsu, K Toda

CHEMISTRY LETTERS ( 7 ) 657 - 658 1997

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

A soi-gel method was applied to prepare thin films of LiLnSiO(4) (Ln=La,Sm). The coating solution was made from lithium isopropoxide, silicon tetraethoxide, and tris(acetylacetonato)rare-earth. Well crystalline films with 0.1 similar to 0.3 mu m in thickness were obtained on alumina and quartz glass substrates by spin-coating, followed by firing over 400 degrees C. The lithium ionic conductivity of the films was much greater than that of sintered samples prepared by a conventional solid state reaction at 1000 degrees C.

DOI： 10.1246/cl.1997.657

Synthesis and Ionic conductivity of New Layered Perovskite Compound, Ag2La2Ti3O10 Reviewed

K. Toda, J. Watanabe, M. Sato

Solid State Ionics 90 15 - 19 1996.12

Synthesis and high ionic conductivity of new layered perovskite compounds, AgLaTa2O7 and AgCa2Ta3O10 Reviewed

K Toda, T Suzuki, M Sato

SOLID STATE IONICS 93 ( 1-2 ) 177 - 181 1996.12

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

New layered perovskite compounds, AgLaTa2O7 and AgCa2Ta3O10, have been synthesized by an ion-exchange reaction from parent compounds, RbLaTa2O7 and RbCa2Ta3O10. The crystal structures of silver ion-exchanged compounds were determined by the Rietveld analysis for powder XRD patterns. These compounds, which are probably metastable, could only be obtained by the ion-exchange reaction. The relatively high ionic conductivities attributed to the interlayer silver ions were observed at high temperatures.

DOI： 10.1016/S0167-2738(96)00518-8

Bulk and grain boundary ionic conduction in lithium rare earth silicates "LiLnSiO4" (Ln = La, Nd, Sm, Eu, Gd, Dy) Reviewed

M. Sato, Y. Kono, H. Ueda, K. Uematsu, K. Toda

Solid State Ionics 83 249 - 256 1996.12

Crystal structure determination and ionic conductivity of layered perovskite compounds NaLnTiO4 (Ln = rare earth) Reviewed

Kenji Toda, Yutaka Kameo, Satoru Kurita, Mineo Sato

Journal of Alloys and Compounds 234 ( 1 ) 19 - 25 1996.2

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

The layered perovskite compounds NaLnTiO4 (Ln = La, Pr, Nd, Sm, Eu, Gd, Y and Lu) were synthesized by the solid state reaction. The crystal structure of these compounds were determined by the Rietveld analysis. Single phases of the compounds (except for Ln = Lu) could be prepared only under very restricted preparation conditions. The composition of NaLuTiO4 was not a single phase under the conditions employed in this study. Compounds NaLnTiO4 have a tetragonal symmetry for Ln = La-Nd, while an orthorhombic symmetry is observed for Ln = Sm-Lu. The stabilization of NaLnTiO4 is discussed on the basis of the relative sizes of the rare earth and the alkali metal ions. The lowering of the symmetry is considered to be introduced by the mismatch between TiO2 and LnO2 layers. Ionic conductivities attributed to the interlayer sodium ions were observed at high temperatures. The magnitude of ionic conductivity of NaLaTiO4, with a single perovskite layer, was much higher than that of Na2La2Ti3O10, with a triple perovskite layer. This high ionic conductivity is due to the weak interaction between the perovskite layer and interlayer sodium ions.

DOI： 10.1016/0925-8388(95)01969-3

New layered perovskite compounds, LiLaTiO4 and LiEuTiO4 Reviewed

K Toda, S Kurita, M Sato

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 104 ( 2 ) 140 - 142 1996.2

Language：English Publishing type：Research paper (scientific journal) Publisher：CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI

New layered perovskite compounds, LiLnTiO(4) (Ln=La and Eu), have been synthesized by an ion-exchange reaction from parent sodium compounds, NaLnTiO(4). The crystal structures of LiLaTiO4 and LiEuTiO4 were determined by Rietveld analysis of the powder X-ray diffraction (XRD) patterns. The lithium ion-exchanged compounds retain the crystal symmetry of the parent phases. Although the framework of the perovskite layer of these compounds is the same as that of the parent compounds, there exists a fundamental difference. The lithium ions within the interlayer have a tetrahedral coordination because of small ionic radius for a rock-salt coordination. The structure of LiLaTiO4 and LiEuTiO4 consist of intergrowths of the perovskite sheets with the layers of Li-O in a tetrahedral coordination and those of Ln-O in a distorted rock-salt coordination. These compounds exhibit new phases analogous to the Ruddlesden-Popper phase.

DOI： 10.2109/jcersj.104.140

Intercalation of water in a layered perovskite compound, NaEuTiO4 Reviewed

Kenji Toda, Yutaka Kameo, Satoru Kurita, Mineo Sato

Bulletin of the Chemical Society of Japan 69 ( 2 ) 349 - 352 1996

Language：English Publishing type：Research paper (scientific journal) Publisher：Chemical Society of Japan

Intercalation of water was observed in a layered perovskite compound, NaEuTiO4, leading to its hydrated derivatives. There are some metastable intermediates in the hydrated derivatives. The hydration process includes several steps that are topotactic. The crystal structure of the hydrated derivatives was identified by Rietveld analysis for the powder X-ray diffraction pattern. It is confirmed that the water molecules are inserted into the sodium layer of NaEuTiO4.

DOI： 10.1246/bcsj.69.349

Synthesis and structure determination of new layered perovskite compounds, ALaTa2O7 and ACa2Ta3O10 (A = Rb, Li) Reviewed

Kenji Toda, Mineo Sato

Journal of Materials Chemistry 6 ( 6 ) 1067 - 1071 1996

Language：English Publishing type：Research paper (scientific journal) Publisher：Royal Society of Chemistry

New layered perovskite compounds of RbLaTa2O7 and RbCa2Ta3O10, whose Rb+ ions can be ion-exchanged have been synthesized directly by a solid-state reaction. Lithium ion-exchanged compounds, LiLaTa2O7 and LiCa2Ta3O10, have also been synthesized by ion-exchange reactions of the rubidium compounds with LiNO3 molten salt. The crystal structures of these compounds have been determined by Rietveld analysis of their powder X-ray diffraction patterns. The crystal structures of these compounds are analogous to those of the corresponding niobate compounds. These compounds are new members of the Diori-Jacobson series with the general formula A[Mn-1BnO3n+i] (A = alkali metal), with n = 2 and 3.

DOI： 10.1039/jm9960601067

　 PREV - NEXT 　

1
2
3
4
5
6
7
8
9
10
11
12