Fan Longlong, Zhang Linxing, Ren Yang, Liu Hui, Xing Xianran, Chen Jun
College of Physics and Materials Science, Tianjin Normal University, Tianjin 300387, China.
Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China.
Inorg Chem. 2020 Sep 21;59(18):13632-13638. doi: 10.1021/acs.inorgchem.0c02002. Epub 2020 Aug 30.
In situ diffraction investigations have played an important role in experimentally revealing the mechanism of piezoelectric and ferroelectric properties. In this study, a pure tetragonal ferroelectric ceramic of La-doped PbZrTiO (LaPZT50) was investigated to eliminate the complex influence of phase coexistence. The electric field evolutions of the crystal structure, domain switching, and lattice deformation of the tetragonal phase have been revealed by in situ high-energy synchrotron X-ray diffraction. We found that the crystal structure of LaPZT50 is quite stable, showing a negligible change in the Pb-O bond length, unit cell volume, and spontaneous polarization upon application of an in situ external electric field. Importantly, the maximum macroscopic polarization of tetragonal LaPZT50 is defined by the 111-oriented grains. As determined by the intensity difference, the switching of non-180° domains plays a more significant role in contributing to the macroscopic strain than lattice deformation. These results further imply that the phase coexistence around the morphotropic phase boundary facilitates domain wall motion in the tetragonal phase and improves the ferroelectric and piezoelectric properties.
原位衍射研究在通过实验揭示压电和铁电性能机制方面发挥了重要作用。在本研究中，对一种纯四方铁电陶瓷La掺杂的PbZrTiO（LaPZT50）进行了研究，以消除相共存的复杂影响。通过原位高能同步辐射X射线衍射揭示了四方相的晶体结构、畴切换和晶格变形的电场演变。我们发现LaPZT50的晶体结构相当稳定，在施加原位外部电场时，Pb-O键长度、晶胞体积和自发极化的变化可忽略不计。重要的是，四方LaPZT50的最大宏观极化由111取向的晶粒决定。根据强度差异确定，非180°畴的切换在贡献宏观应变方面比晶格变形起更重要的作用。这些结果进一步表明，准同型相界周围的相共存促进了四方相中的畴壁运动，并改善了铁电和压电性能。
