Faculty Profiles - TANIGUCHI Hiroki

Papers - TANIGUCHI Hiroki

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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.

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

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

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

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

Effect of Oxygen Isotope Exchange on Ferroelectric Microregion in SrTiO_3 Studied by Raman Scattering

谷口博基

Journal of the Physical Society of Japan Vol.73 page： 3262 - 3265 2004

2003-05-15

Taniguchi Hiroki, Machida Mitsuo, Koyano Nobumitsu

Journal of the Physical Society of Japan Vol. 72 ( 5 ) page： 1111-1117 2003.5

Neutron diffraction study of crystal structures of glycinium phosphite H<inf>3</inf>NCH<inf>2</inf>COOH·H<inf>2</inf>PO<inf>3</inf> in paraelectric and ferroelectric phases Reviewed

Hiroki Taniguchi, Mitsuo Machida, Nobumitsu Koyano

Journal of the Physical Society of Japan Vol. 72 ( 5 ) page： 1111 - 1117 2003.5

Language：English Publishing type：Research paper (scientific journal) Publisher：THE PHYSICAL SOCIETY OF JAPAN

Crystal structure of H3NCH2COOH·H 2PO3 was studied in the paraelectric phase (P phase) at 298 K and in the ferroelectric phase (F phase) at 170 K by means of the single crystal neutron diffraction. Two independent protons in the hydrogen bonds forming the H(HPO3)- chains are disordered over two sites with the separations of 0.486(3) and 0.474(5) Å in the P phase. In the F phase, they are ordered at a position nearly equal to one of two sites related by the disorder. With the proton order, lengths of the P-O bonds with the oxygens involved in the hydrogen bonds forming the chain deviate from their values determined in the P phase. A possible mechanism for the appearance of the spontaneous polarization is discussed in connection with the deformation of the HPO32- anions in the F phase. © 2003 The Physical Society of Japan.

DOI： 10.1143/JPSJ.72.1111

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