Investigation of the exotic properties originated from a large tetragonal distrotion

• Project/Area Number: 26800180
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Condensed matter physics II
• Research Institution: Chuo University
• Principal Investigator: Oka Kengo 中央大学, 理工学部, 助教 (80602044)
• Project Period (FY): 2014-04-01 – 2016-03-31
• Project Status: Completed (Fiscal Year 2015)
• Budget Amount: ¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000); Fiscal Year 2015: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000); Fiscal Year 2014: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
• Keywords: 精密構造解析 / 放射光粉末X線回折 / リートベルト解析 / 酸フッ化物 / 固体化学 / 構造物性 / アニオン複合化

Outline of Final Research Achievements

New oxyfluoride system which contains Pb and Ti was invesitigated based on the tetragonal perovskite PbTiO3. Our study found novel oxyfluorides, Pb2Ti4O9F2とPb2Ti2O5.4F1.2. Bond valence sum calculations and determining electron density distribution by the maximum entropy method reveled presence of O/F anion order in Pb2Ti4O9F2. Pb2Ti2O5.4F1.2 was a pyrochlore with centrosymmetric space group, however, exhibited an unusual large dielectric constant. Presence of local distortion may be the origin of the high dielectric constant.

Research Products

• [Journal Article] Observation of anion order in Pb2Ti4O9F2 (2015)
  • Author(s): K. Oka and K. Oh-ishi
  • Journal Title: Inorganic Chemistry Volume: 54 Pages: 10239-10242
  • DOI: 10.1021/acs.inorgchem.5b01496
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Negative thermal expansion induced by intermetallic charge transfer (2015)
  • Author(s): Masaki Azuma, Kengo Oka, Koichiro Nabetani
  • Journal Title: Science and Technology of Advanced Materials Volume: 16 Pages: 034904-034904
  • DOI: 10.1088/1468-6996/16/3/034904
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] New PbTiO3-Type Giant Tetragonal Compound Bi2ZnVO6 and Its Stability under Pressure (2015)
  • Author(s): Runze Yu, Hajime Hojo, Kengo Oka, Tetsu Watanuki, Akihiko Machida, Keisuke Shimizu, Kiho Nakano, and Masaki Azuma
  • Journal Title: Chemistry of Materials Volume: 27 Pages: 2012-2017
  • DOI: 10.1021/cm504133e
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Melting of Pb Charge Glass and Simultaneous Pb-Cr Charge Transfer in PbCrO3 as the Origin of Volume Collapse (2015)
  • Author(s): R. Yu, H. Hojo, T. Watanuki, M. Mizumaki, T. Mizokawa, K. Oka, H. Kim, A. Machida, K. Sakaki, Y. Nakamura, A. Agui, D. Mori, T. Inaguma, M. Schlipf, K. Z. Rushshanskii, M. Lezaic, M. Matsuda, J. Ma, S. Calder, M. Isobe, Y. Ikuhara, and M. Azuma
  • Journal Title: Journal of the American Chemical Society Volume: 137 Pages: 12719-12728
  • DOI: 10.1021/jacs.5b08216
  • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Suppression of temperature hysteresis in negative thermal expansion compound BiN1－xFexO3 and zero-thermal expansion composite (2015)
  • Author(s): K. Nabetani, Y. Muramatsu, K. Oka, K. Nakano,1 H. Hojo, M. Mizumaki, A. Agui, Y. Higo, N. Hayashi, M. Takano, and M. Azuma
  • Journal Title: Applied Physics Letters Volume: 106 Pages: 061912-061912
  • DOI: 10.1063/1.4908258
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Superconductivity in Noncentrosymmetric Iridium Silicide Li2IrSi3 (2014)
  • Author(s): S. Pyon, K. Kudo, J. Matsumura, H. Ishii, G. Matsuo, M. Nohara, H. Hojo, K. Oka, M. Azuma, V. Ovidiu Garlea, K. Kodama, and S. Shamoto
  • Journal Title: J. Phys. Soc. Jpn. Volume: 83 Issue: 9 Pages: 093706-093706
  • DOI: 10.7566/jpsj.83.093706
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] High-pressure synthesis of BaVO3: A new cubic perovskite (2014)
  • Author(s): K. Nishimura, I. Yamadab, K. Oka, Y. Shimakawa and M. Azuma
  • Journal Title: Journal of Physics and Chemistry of Solids Volume: 75 Pages: 710-712
  • DOI: 10.1016/j.jpcs.2014.02.001
  • Peer Reviewed
• [Presentation] パイロクロア酸フッ化物 Pb2Ti2O6-δ F2δ の結晶構造と物性 (2016)
  • Author(s): 岡研吾・大石克嘉・ 北條元・東正樹
  • Organizer: 日本セラミックス協会2016年会
  • Place of Presentation: 早稲田大学
  • Year and Date: 2016-03-14
• [Presentation] Synthesis and structural study of Pb containing oxyfluoride (2015)
  • Author(s): Kengo Oka, Katsuyoshi Oh-ishi
  • Organizer: Pacifichem 2015
  • Place of Presentation: Hawaii convention center
  • Year and Date: 2015-12-15
  • Int'l Joint Research
• [Presentation] 単結晶 PbVO3の高圧下電気抵抗測定 (2015)
  • Author(s): 岡 研吾・山内 徹・上床 美也・東 正樹・ 大石 克嘉
  • Organizer: 第56回高圧討論会
  • Place of Presentation: JMSアステールプラザ
  • Year and Date: 2015-11-10
• [Presentation] Observation of anion order in Pb2Ti4O9F2 (2015)
  • Author(s): Kengo Oka, Katsuyoshi Oh-ishi
  • Organizer: STAC9, TOEO-9
  • Place of Presentation: sukuba International Congress Center
  • Year and Date: 2015-10-19
  • Int'l Joint Research
• [Presentation] 酸フッ化物PbO-PbF2-TiO2系の合成と構造解析 (2015)
  • Author(s): 岡研吾・大石克嘉
  • Organizer: 日本セラミックス協会第28回秋季シンポジウム
  • Place of Presentation: 富山大学
  • Year and Date: 2015-09-16
• [Presentation] 新規鉛含有酸フッ化物の合成と結晶構造 (2015)
  • Author(s): 岡研吾、大石克嘉
  • Organizer: 日本セラミックス協会 2015年会
  • Place of Presentation: 岡山大学
  • Year and Date: 2015-03-18 – 2015-03-20
• [Presentation] ペロブスカイトAA’BB’O6 の高圧合成および構造・物性評価 (2014)
  • Author(s): 岡研吾，北條元，深谷亮，成瀬卓，沖本洋一，東正樹，綿貫徹， KIM Hyunjeong，町田晃彦，榊浩司、大石克嘉
  • Organizer: 第55回高圧討論会
  • Place of Presentation: 徳島大学
  • Year and Date: 2014-11-22 – 2014-11-24
• [Remarks] 温めると縮む不思議な材料
  • URL: http://www.yomiuri.co.jp/adv/chuo/research/20150430.html