铁电性
材料科学
居里温度
中子衍射
八面体
化学计量学
极化(电化学)
结晶学
晶体结构
凝聚态物理
矿物学
电介质
铁磁性
化学
光电子学
物理化学
物理
作者
Yuichi Shimakawa,Yoshimi Kubo,Yasuaki Nakagawa,Takashi Kamiyama,H. Asano,Fujio Izumi
摘要
Crystal structures of ferroelectric materials of stoichiometric SrBi2Ta2O9 (TC=300 °C) and Sr-deficient-and-Bi-excess Sr0.8Bi2.2Ta2O9 (TC=400 °C) were refined by neutron powder diffraction. Bi2O2 layer and TaO6 octahedra are considerably distorted and atomic displacements along the a axis cause ferroelectric spontaneous polarization. In Sr0.8Bi2.2Ta2O9, both Bi substitution and cation vacancies at the Sr site were revealed and a chemical composition of (Sr0.82Bi0.12)Bi2Ta2O9.0 was obtained. The calculated polarization of Sr0.8Bi2.2Ta2O9 is larger than that of the stoichiometric sample, which is consistent with observations of remanent polarization in thin-film capacitors. The Bi substitution and the cation vacancies at the Sr site enhance structural distortion in the TaO6 octahedra and lead to the larger ferroelectric spontaneous polarization and the higher Curie temperature.
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