arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0903.0684cond-mat.mtrl-scicond-mat.other
收藏

原子法测定晶体硅的挠曲电性质

Atomistic determination of flexoelectric properties of crystalline dielectrics

R. Maranganti, P. Sharma

摘要:

在施加均匀应变时,非中心对称电介质晶体的晶胞内的内部子晶格移位导致净偶极矩的出现:一种众所周知的压电现象。另一方面,宏观应变梯度可以在任何晶体结构的晶体中诱导极化,即使是具有中心对称晶格的晶体。这种现象,称为挠曲电,具有体和表面贡献:体贡献的强度可以通过称为体挠曲电张量的材料性质张量来表征。最近的几项研究表明,应变梯度诱导极化可能是材料中各种有趣和异常机电现象的原因,包括非均匀应变纳米结构中的机电耦合效应,纳米电容器系统中的死层效应,以及钙钛矿纳米结构中的巨压电性等。在这项工作中,采用晶格动力学为基础的微观方法,我们提供了某些立方离子晶体,钙钛矿晶体,III-V族和II-VI族半导体的挠曲电张量的估计。我们将我们的估计与实验和理论值进行比较,解决不同实验估计之间存在的差异,并重新访问现有的经验缩放关系的有效性,挠曲电系数的大小在材料参数方面。

英文摘要:

Upon application of a uniform strain, internal sub-lattice shifts within the unit cell of a non-centrosymmetric dielectric crystal result in the appearance of a net dipole moment: a phenomenon well known as piezoelectricity. A macroscopic strain gradient on the other hand can induce polarization in dielectrics of any crystal structure, even those which possess a centrosymmetric lattice. This phenomenon, called flexoelectricity, has both bulk and surface contributions: the strength of the bulk contribution can be characterized by means of a material property tensor called the bulk flexoelectric tensor. Several recent studies suggest that strain-gradient induced polarization may be responsible for a variety of interesting and anomalous electromechanical phenomena in materials including electromechanical coupling effects in non-uniformly strained nanostructures, dead layer effects in nanocapacitor systems, and giant piezoelectricity in perovskite nanostructures among others. In this work, adopting a lattice dynamics based microscopic approach we provide estimates of the flexoelectric tensor for certain cubic ionic crystals, perovskite dielectrics, III-V and II-VI semiconductors. We compare our estimates with experimental and theoretical values wherever available, address the discrepancy that exists between different experimental estimates and also re-visit the validity of an existing empirical scaling relationship for the magnitude of flexoelectric coefficients in terms of material parameters.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑