We investigate the role of polycrystalline disorder on the effective ferro-electro-elastic behavior of perovskite ferroelectric ceramics under electro-mechanical loading. Assuming random initial grain orientations, we use high-resolution phase-field simulations and periodic homogenization of two-dimensional model polycrystals to study the evolution of the domain microstructure within and across grains as well as the resulting effective, macroscopic polarization and strain fields under loading. The number of randomly-oriented grains in simulations, at fixed grain size and fixed numerical resolution per grain, is used to control the polycrystalline disorder. Results indicate that, when the polycrystalline samples are sufficiently disordered (i.e., when sufficiently many randomly-oriented grains are considered), their effective electromechanical response under uniaxial compression is stable, and the concomitant polarization and deformation are always aligned with the mechanical load. Thus, the present study supports the viewpoint that polycrystalline disorder in bulk perovskite ceramics stabilizes the overall ferro-electro-elastic response despite the underlying nonconvex polarization energy landscape.

中文翻译：

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模型多晶中铁电弹性的相场模拟对块状钙钛矿陶瓷的现象学描述具有影响


我们研究了多晶无序对机电负载下钙钛矿铁电陶瓷的有效铁电弹性行为的作用。假设随机初始晶粒取向，我们使用高分辨率相场模拟和二维模型多晶的周期性均质化来研究晶粒内部和晶粒之间的域微观结构的演化，以及在负载下产生的有效宏观极化和应变场。模拟中随机取向的晶粒数量（在固定晶粒尺寸和每个晶粒的固定数值分辨率下）用于控制多晶无序。结果表明，当多晶样品足够无序时（即，当考虑足够多的随机取向晶粒时），它们在单轴压缩下的有效机电响应是稳定的，并且伴随的极化和变形始终与机械载荷一致。因此，本研究支持这样的观点：尽管存在潜在的非凸极化能量景观，但块状钙钛矿陶瓷中的多晶无序稳定了整体铁电弹性响应。