Faculty Profiles - TANIGUCHI Hiroki

Papers - TANIGUCHI Hiroki

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Fabrication of BaTi<inf>2</inf>O<inf>5</inf> glass-ceramics with unusual dielectric properties during crystallization

Yu J.

Chemistry of Materials Vol. 18 ( 8 ) page： 2169 - 2173 2006.4

Crystal growth of 50mg-class single crystals of beta '-(BEDT-TTF)(2)ICl2 and crystal evaluation

Taniguchi H., Sato R., Satoh K., Kawamoto A., Okamoto H., Kobayasi T., Mizuno K.

JOURNAL OF LOW TEMPERATURE PHYSICS Vol. 142 ( 3-4 ) page： 437 - 440 2006.2

Raman scattering study of superionic conductor lithium tetraborate Li <inf>2</inf>B<inf>4</inf>O<inf>7</inf> Reviewed

Tatiana Dekola, Toshirou Yagi, Hiroki Taniguchi, Masaki Takesada, Ichiro Sekine

Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers Vol. 45 ( 1 A ) page： 152 - 154 2006.1

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

Raman scattering spectra of the superionic-conductive lithium tetraborate Li2B4O7 are observed in the frequency range between 0-1600cm-1 as a function of temperature from 4.2K to room temperature. The frequencies of four Raman active AI (TO) modes of 262, 353, 378, and 423 cm-1 at 4.2 K are newly assigned to be related closely with the motion of the Li-ions in superionic conduction. © 2006 The Japan Society of Applied Physics.

DOI： 10.1143/JJAP.45.152

Web of Science

Scopus

In Situ Raman Scattering Study on Successive Crystallization of Bulk BaTi2O5 Glass

Taniguchi Hiroki, Yu Jianding, Arai Yasutomo, Yagi Toshirou, Fu Desheng, Itoh Mitsuru

Abstract book of Russia/CIS/Baltic/Japan Symposium on Ferroelectricity Vol. 2006 ( 0 ) page： 42 - 42 2006

Soft mode dynamics in O-18-exchanged SrTiO3 as inhomogeneous system Reviewed

Hiroki Taniguchi, Mitsuru Itoh, Masaki Takesada, Toshirou Yagi

TRANSACTIONS OF THE MATERIALS RESEARCH SOCIETY OF JAPAN, VOL 31, NO 1 Vol. 31 ( 1 ) page： 97 - 100 2006

Language：English Publishing type：Research paper (international conference proceedings) Publisher：ELSEVIER SCIENCE BV

Ferroelectric phase transition of quantum paraelectric SrTiO3 is induced by an exchange of O-16 for its isotope O-18 in a low temperature region. The dynamics of ferroelectric soft mode in weakly O-18-exchanged strontium titanate is studied by Raman scattering. A nominally Raman-inactive soft mode is observed in the paraelectric phase of SrTi((O0.32O0.68)-O-18-O-16)(3) due to the local symmetry-breaking. The observed soft mode spectrum shows the temperature dependence strongly affected by the inhomogeneity of the system. The soft mode nonuniformly freezes to induce the local ferroelectric order before the onset of ferroelectric phase. The dynamical inhomogeneity is concluded to play an essential role in the dielectric response of O-18-exchanged strontium titanate.

Web of Science

Ferroelectricity of SrTi18O3: Paradox in the Phase Transition Mechanism

Itoh Mitsuru, Taniguchi Hiroki

Abstract book of Russia/CIS/Baltic/Japan Symposium on Ferroelectricity Vol. 2006 ( 0 ) page： 3 - 3 2006

Conductive Boundary Layer in CaCu3Ti4O12 with Giant-Dielectric-Response

Fu Desheng, Arima Yosuke, Taniguchi Hiroki, Taniyama Tomoyasu, Itoh Mitsru, Yu Jianding, Koshihara Shin-ya

Abstract book of Russia/CIS/Baltic/Japan Symposium on Ferroelectricity Vol. 2006 ( 0 ) page： 80 - 80 2006

In Situ Raman Scattering Study on Crystallization of Bulk BaTi2O5 Glass

Taniguchi Hiroki, Yu Jianding, Arai Yasutomo, Yagi Toshirou, Fu Desheng, Itoh Mitsuru

Preprints of Annual Meeting of The Ceramic Society of Japan<br>Preprints of Fall Meeting of The Ceramic Society of Japan Vol. 2006 ( 0 ) page： 19 - 19 2006

Isotope effect on the soft-mode dynamics of SrTiO3 studied by Raman scattering Reviewed Open Access

H. Taniguchi, T. Yagi, M. Takesada, M. Itoh

Physical Review B - Condensed Matter and Materials Physics Vol. 72 ( 6 ) 2005.8

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER PHYSICAL SOC

The oxygen isotope effect on the soft-mode dynamics in quantum paraelectric SrTi (Ox18 O 1-x 16) 3 [STO18- x] is investigated by Raman scattering in terms of local symmetry breaking in the paraelectric phase. The exchange rates x of the O18 atoms are 0.23 [STO18-23] and 0.32 [STO18-32], which are less than the critical value xc (=0.33). In STO18-32, whose exchange rate is just below xc, the soft Eu mode shows hardening behavior in a low-temperature region indicating the onset of local ferroelectric order. On the other hand, the soft Eu mode in STO18-23 does not show any hardening behavior until 0 K. The enhancement of the inhomogeneity in the crystal by the exchange of O18 is concluded to play an essential role in the soft-mode dynamics of the quantum paraelectric and ferroelectric STO18- x. The relation between the soft-mode dynamics and quantum fluctuation is discussed. © 2005 The American Physical Society.

DOI： 10.1103/PhysRevB.72.064111

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Scopus

Growth of ferroelectric micro-regions in SrTiO3 and SrTi((O0.23O0.77)-O-18-O-16)(3) studied by Raman scattering Reviewed

Taniguchi H, Yagi T, Takesada M, Itoh M

JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol. 46 ( 1 ) page： 195 - 197 2005.1

19pYM-11 Raman Scattering Study of Superionic Conductor Lithium Tetraborate Li_2B_4O_7. Part II Open Access

Dekola Tatiana, Yagi Toshirou, Taniguchi Hiroki, Takesada Masaki, Sekine Ichiro

Meeting Abstracts of the Physical Society of Japan Vol. 60.2.4 ( 0 ) page： 803 2005

25pYR-2 Soft Mode and Precursory Lowing of Local Symmetry in Quantum Paraelectric STO18 Open Access

Taniguchi H., Takesada M., Itoh M., Yagi T.

Meeting Abstracts of the Physical Society of Japan Vol. 60.1.4 ( 0 ) page： 913 2005

24aYR-7 Low-frequency modes in Li_2B_4O_7 crystals studied by Raman scattering Open Access

Dekola Tatiana, Taniguchi Hiroki, Takesada Masaki, Sekine Ichiro, Yagi Toshirou

Meeting Abstracts of the Physical Society of Japan Vol. 60.1.4 ( 0 ) page： 890 2005

Growth of Ferroelectric Micro-regions in SrTiO_3 and SrTi(^<18>O_<0.23>^<16>O_<0.77>)_3 Studied by Raman Scattering

谷口博基

Journal of the Korean Physical Society Vol.46 page： 195 - 197 2005

Effect of Oxygen Isotope Exchange on Ferroelectric Microregion in SrTiO3Studied by Raman Scattering

Taniguchi Hiroki, Takesada Masaki, Itoh Mitsuru, Yagi Toshirou

Journal of the Physical Society of Japan Vol. 73 ( 12 ) page： 3262 - 3265 2004.12

Effect of oxygen isotope exchange on ferroelectric microregion in SrTiO<inf>3</inf> studied by Raman scattering Reviewed

Hiroki Taniguchi, Masaki Takesada, Mitsuru Itoh, Toshirou Yagi

Journal of the Physical Society of Japan Vol. 73 ( 12 ) page： 3262 - 3265 2004.12

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

The ferroelectric microregion (FMR) in quantum paraelectric SrTiO 3 is studied by Raman scattering using an optical cryostat with a 3He refrigerator. By the partial exchange of the oxygen atom for its isotope 18O, broad FMR spectra change drastically to underdamped Lorentzian-type spectra with decreasing temperature below 10 K. The peak is assigned to the ferroelectric soft Eu mode. The intense and sharp spectra of the Eu mode, which are nominally Raman inactive, indicate that the symmetry is lowered to a non-centrosymmetric symmetry in FMR. Furthermore, the softening characteristic of the soft Eu mode in a low-temperature region implies that the symmetry is not necessarily ferroelectric. The local symmetry breaking is enhanced by the substitution of the isotope 18O. © 2004 The Physical Society of Japan.

DOI： 10.1143/JPSJ.73.3262

Web of Science

Scopus

CiNii Research

Neutron Diffraction Study of Crystal Structures of Deuterated Glycinium Phosphite in Paraelectric and Ferroelectric Phases

Machida Mitsuo, Uchida Hiroyuki, Ishibashi Toku, TANIGUCHI Hiroki, KOMUKAE Masaru, OSAKA Toshio, KOYANO Nobumitsu

Journal of the Physical Society of Japan Vol. 73 ( 1 ) page： 107 - 115 2004.1

Publishing type：Research paper (scientific journal) Publisher：一般社団法人日本物理学会

Crystal structure of deuterated glycinium phosphite was studied in the paraelectric (P) phase at 348 K and in the ferroelectric (F) phase at 223 K by means of the single crystal neutron diffraction. Deuteration rate is estimated to be 0.939 by the least-squares refinement. In the P phase, quasi-one-dimensional hydrogen bond chains are built by mutually linking the DPO^<2->_3 anions through two different types of hydrogen bonds with the bond angles of 179.2 and 171.6°. Two independent deuterons within the hydrogen bonds forming the chains are disordered over two sites separated by 0.545 and 0.539 Å. In the F phase, they order at a position nearly equal to one of two sites related by the disorder in the P phase. With the ordering of the deuterons, the P-O bonds with covalently bonded deuteron elongate, and those without covalently bonded deuteron reduce their lengths to some extent from the values determined in the P phase. Two oxygens involved in the hydrogen bond with the bond angle 179.2° exhibits especially large displacements in the F phase. This suggests strongly an importance of this hydrogen bond in the polarization appearance and in the ferroelectric transition. Comparison with results of non-deuterated salt indicates that only the hydrogen bonds forming the chains show significant isotope shift. In particular, the hydrogen bond with the bond angle 179.2° exhibits the most pronounced shift on the angle parameter defined by the angle between the line connecting two sites of disordered proton or deuteron and the line connecting two oxygens involved in the hydrogen bond.

DOI： 10.1143/JPSJ.73.107

CiNii Research

Neutron Diffraction Study of Crystal Structures of Deuterated Glycinium Phosphite in Paraelectric and Ferroelectric Phases

Machida Mitsuo, Uchida Hiroyuki, Ishibashi Toku, Taniguchi Hiroki, Komukae Masaru, Osaka Toshio, Koyano Nobumitsu

Journal of the Physical Society of Japan Vol. 73 ( 1 ) page： 107 - 115 2004.1

Neutron diffraction study of crystal structures of deuterated glycinium phosphite in paraelectric and ferroelectric phases Reviewed

Mitsuo Machida, Hiroyuki Uchida, Toku Ishibashi, Hiroki Taniguchi, Masaru Komukae, Toshio Osaka, Nobumitsu Koyano

Journal of the Physical Society of Japan Vol. 73 ( 1 ) page： 107 - 115 2004.1

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

Crystal structure of deuterated glycinium-phosphite was studied in the paraelectric (P) phase at 348 K and in the ferroelectric (F) phase at 223 K by means of the single crystal neutron diffraction. Deuteration rate is estimated to be 0.939 by the least-squares refinement. In the P phase, quasi-one-dimensional hydrogen bond chains are built by mutually linking the DPO32- anions through two different types of hydrogen bonds with the bond angles of 179.2 and 171.6°. Two independent deuterons within the hydrogen bonds forming the chains are disordered over two sites separated by 0.545 and 0.539 Å. In the F phase, they order at a position nearly equal to one of two sites related by the disorder in the P phase. With the ordering of the deuterons, the P-O bonds with covalently bonded deuteron elongate, and those without covalently bonded deuteron reduce their lengths to some extent from the values determined in the P phase. Two oxygens involved in the hydrogen bond with the bond angle 179.2° exhibits especially large displacements in the F phase. This suggests strongly an importance of this hydrogen bond in the polarization appearance and in the ferroelectric transition. Comparison with results of non-deuterated salt indicates that only the hydrogen bonds forming the chains show significant isotope shift. In particular, the hydrogen bond with the bond angle 179.2° exhibits the most pronounced shift on the angle parameter defined by the angle between the line connecting two sites of disordered proton or deuteron and the line connecting two oxygens involved in the hydrogen bond. ©2004 The Physical Society of Japan.

DOI： 10.1143/JPSJ.73.107

Web of Science

Scopus

CiNii Research

13pTL-9 An Isotope Effect on Ferroelectric Micro Region in SrTiO_3 Open Access

Taniguchi H., Takesada M., Itoh M., Yagi T.

Meeting Abstracts of the Physical Society of Japan Vol. 59.2.4 ( 0 ) page： 867 2004

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