摘要
利用SEM观察了未疲劳和疲劳铁电陶瓷极化试样的断口形貌.利用原位XRD观测了电疲劳过程中极化试样表面铁电电畴的变化,并记录了相应的剩余极化强度.实验结果表明:疲劳试样的主要断裂模式为沿晶断裂;随疲劳次数的增加,每次疲劳后试样表面I(002)减小,I(200)增加;每次疲劳后在外加电场作用下试样表面I(002)增加幅度和I(200)减小幅度随疲劳次数的增加而减少.这些现象说明:可翻转电畴的减少是剩余极化强度降低的主要原因;非协调高畴变应变形成大量沿晶微裂纹并导致疲劳试样主要断裂模式为沿晶断裂;沿晶微裂纹的形成和伸长主要发生在电疲劳的初期.
An in situ XRD method was employed to identify variations of electric domains on the surfaces of poled PLZT samples during an electric fatigue process, and simultaneously, the related remnant polarization was measured. The SEM observation revealed that the major fracture mode for fatigued samples is intergranular. The diffraction intensities, I-(002) and I-(200), after each cycle decreased and increased, respectively, and their magnitudes of the increment and decrement lowered as the number of cycles increased. It is suggested that the reduction in magnitude of remnant polarization is caused by the reduction in numbers of switch-able domains during a fatigue process. In addition, the incompatible high strain induced the intergranular micro-cracks in the material, which leads the major fracture mode for the fatigued sample to be intergranular. The formation and the elongation of micro-cracks in samples mainly occurred at earlier stage of electric fatigue.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2004年第12期1299-1304,共6页
Acta Metallurgica Sinica
基金
国家自然科学基金资助项目20073036
关键词
PLZT铁电陶瓷
电疲劳
90°畴变
应变
微裂纹
ferroelectric ceramics PLZT
electric fatigue
90 degrees domain reorientation
strain
micro-crack
