In many ferroelectrics, large electromechanical strains are observed near regions of composition- or temperature- driven phase coexistence. Phenomenologically, this is attributed to easy re-orientation of the polarization vector and/or phase transition, although their effects are highly convoluted and difficult to distinguish experimentally. Here, we used synchrotron X-ray scattering and digital image correlation to differentiate between the microscopic mechanisms leading to large electrostrains in an exemplary Pb-free piezoceramic Sn-doped barium calcium zirconate titanate. Large electrostrains of ~0.2% measured at room-temperature are attributed to an unconventional effect, wherein polarization switching is aided by a reversible phase transition near the tetragonal-orthorhombic phase boundary. Additionally, electrostrains of ~0.1% or more could be maintained from room temperature to 140 °C due to a succession of different microscopic mechanisms. In situ X-ray diffraction elucidates that while 90° domain reorientation is pertinent below the Curie temperature (T_C), isotropic distortion of polar clusters is the dominant mechanism above T_C.

在许多铁电体中，在组成或温度驱动相共存的区域附近观察到较大的机电应变。从现象学上讲，这归因于偏振矢量的容易重新定向和/或相变，尽管它们的影响高度复杂且难以通过实验区分。在这里，我们使用同步加速器X射线散射和数字图像相关性来区分导致典型的无铅压电陶瓷Sn掺杂锆钛酸钡钛酸钡中的大电应变的微观机理。在室温下测得的〜0.2％的大电应变归因于非常规效应，其中极化转换由四方-斜方晶相边界附近的可逆相变辅助。此外，电应变为〜0。由于一系列不同的微观机制，从室温到140°C可以保持1％或更多。原位X射线衍射表明，在居里温度以下，虽然90°域重新定向是适当的（T _C），极性簇的各向同性畸变是T _C之上的主要机制。