Statistical Theory for Displacement Ferroelectrics. III. Comparison with Experiment for Lithium Tantalate
Statistical Theory for Displacement Ferroelectrics. III. Comparison with Experiment for Lithium Tantalate
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位移铁电体的统计理论。
DOI：
10.1103/physrev.177.819
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发表时间：
1969
期刊：
影响因子：
--
通讯作者：
M. Lines
中科院分区：
文献类型：
--
作者：
M. Lines
在本系列论文的第一部分和第二部分中发展的理论被用来解释LiTaO_3的介电性质。这个问题被轻松地超定了，既允许确定理论中涉及的参数，也允许对理论本身进行一致性检验。使用完全与温度无关的参数，理论和实验之间的一致性很好，但如果允许洛伦兹场参数与温度的关系，则会变得很好。当得到的有效哈密顿量参数的值与用微观模型对系统的详细描述有关时，很明显，用不同核位置的一组有效点电荷来表示是不够的。建议用核电荷和壳电荷两种有效电荷来表示每个离子可能更合适。
The theory developed in parts I and II of the present series of papers is used to interpret the dielectric properties of LiTa O 3. The problem is comfortably overdetermined, allowing both for a determination of the parameters involved in the theory and for a consistency check of the theory itself. The agreement between theory and experiment is quite good using completely temperature-independent parameters, but becomes excellent if a temperature dependence of the Lorentz field parameter is allowed. When the values obtained for the parameters of the effective Hamiltonian are related to a detailed description of the system in terms of a microscopic model, it becomes apparent that a representation in terms of a set of effective point charges at the various nuclear sites is inadequate. It is suggested that a representation of each ion by two effective charges, a core charge and a shell charge, may be more appropriate.