Charge Density Study on Phase Transition in BaTi2O5 Ferroelectric
Charge Density Study on Phase Transition in BaTi2O5 Ferroelectric
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DOI：
10.1143/jjap.48.09kf06
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发表时间：
2009-09-01
影响因子：
1.5
通讯作者：
Masuno, Atsunobu
中科院分区：
文献类型：
--
作者：
Moriyoshi, Chikako;Okizaki, Naoya;Masuno, Atsunobu
在100 ~ 900 K的电荷密度水平下，得到了BaTi_2O_5铁电体顺电相和铁电相的精确晶体结构。采用最大熵方法（MEM）和Rietveld方法对高能同步辐射粉末衍射数据进行了分析。BaTi_2O_5结构中有三个独立的Ti-O-6八面体发生畸变，其中两个八面体在两相中都具有五氧配位。与铁电相变相关的结构变化的特征是在T-C以上畸变最小的八面体Ti 1-O-6中发生了额外的畸变。由测定的晶体结构计算出室温下的自发极化率为Ps = 15 μ C/cm（2）。Ti 1-O-6畸变对Ps的贡献约为80%。(C)2009日本应用物理学会
The accurate crystal structure of BaTi2O5 ferroelectric has been derived at the charge density levels from 100 to 900 K in both the paraelectric and ferroelectric phases. High-energy synchrotron-radiation powder-diffraction data were taken and analyzed by the maximum entropy method (MEM)/Rietveld method. Three independent Ti-O-6 octahedra in the structure of BaTi2O5 are distorted, two of which can be regarded as having five-oxygen coordination in both phases. The structural change associated with the ferroelectric phase transition is characterized by the occurrence of extra distortion in Ti1-O-6, which is the least distorted octahedron above T-C. The spontaneous polarization calculated from the determined crystal structure is P-s = 15 mu C/cm(2) at room temperature. The contribution of the distortion of Ti1-O-6 to Ps is about 80%. (C) 2009 The Japan Society of Applied Physics