The atomistic origin of the inverse piezoelectric effect in α-quartz
The atomistic origin of the inverse piezoelectric effect in α-quartz
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α-石英中逆压电效应的原子起源
DOI：
10.1016/j.jpcs.2004.08.008
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发表时间：
2004
影响因子：
4
通讯作者：
P. Blaha
中科院分区：
文献类型：
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作者：
V. Kochin;J. Davaasambuu;U. Pietsch;K. Schwarz;P. Blaha
为了了解α-石英中逆压电效应的原子起源，采用FP-APW+lo方法进行了从头计算。为了在包含72个原子的超级单体（SC）内实现平动对称，外电场由锯齿状电位Vextin模拟。原三角石英结构沿[110]方向重复，与外场方向相对应。施加550kV/mm的电场，放松SC的原子位置，直到作用在原子上的力消失。在SC的某些部分，vextx几乎是线性变化的，因此松弛的原子位置可以用来确定由于外电场引起的结构响应。计算结果提供了正确数量级的压电模量。与以前的模型相反，并与最近的实验结果一致，压电效应的原子起源可以通过轻微变形的sio4四面体相互旋转来描述。Si-O键长和四面体O-Si-O角的变化比相邻四面体之间的Si-O - si角的变化小一个数量级。当将理论数据外推到实验中应用的更小的场强（E<10kV/mm）时，计算出的x射线结构因子变化与实验一致。
Ab initio calculations have been carried out using the FP-APW+lo method in order to understand the atomic origin of the inverse piezoelectric effect in α-quartz. The external electric field was modelled by a saw-like potential Vextin order to achieve translational symmetry within a supercell (SC) containing 72 atoms. The original trigonal quartz structure was repeated along the [110] direction, which corresponds to the direction of the external field. An electric field with 550kV/mm was applied and the atomic positions of the SC were relaxed until the forces acting on the atoms vanished. In parts of the SC, Vextchanges almost linearly and thus the relaxed atomic positions can be used to determine the structural response due to the external electric field. The calculations provide the piezoelectric modulus of the correct order of magnitude. In contrast to previous models and in agreement with recent experimental results, the atomic origin of the piezoelectric effect can be described by a rotation of slightly deformed SiO4tetrahedra against each other. The change of the Si–O bond lengths and the tetrahedral O–Si–O angles is one order of magnitude smaller than that of the Si–O–Si angles between neighbouring tetrahedra. The calculated changes of X-ray structure factors are in agreement with experiment when the theoretical data are extrapolated down to the much smaller field strength that is applied in the experiment (E<10kV/mm).
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