In-situ Raman Observation of Domain Switching near Crack Tip in PLZT Ferroelectric Ceramics

采用传统固相法制备了平均晶粒尺寸为5; mum的四方结构掺镧锆钛酸铅(PLZT)铁电陶瓷,在其表面涂银、切向预极化后刻蚀出刻槽,在刻槽表面压出维氏压痕并沿预极化方向施加外电场,利用Ra; man光谱原位观测了压痕裂纹尖端附近不同位置的畴变,分析了Raman软模E(2TO)和E(3TO+2LO)+B1峰的强度随观测点的变化规律。结果; 表明:在外电场作用下,裂纹尖端会发生电致应变和90°畴变;Raman谱和软模E(2TO)、E(3TO+2LO)+B1峰强度均会随着观测点距裂纹尖; 端距离的增大而减弱。Lanthanum-doped lead zirconate titanate (PLZT) ferroelectric ceramics; with average grain size of 5 mm and a tetragonal structure were prepared; by the conventional solid state reaction method, and then were surface; coated with silver and pre-polarized in tangential direction. Then a; groove was etched in the silvered surface of the ceramics, sbsequently; Vickers indentation was introduced on the groove surface and external; electric field was applied along the pre-polarization direction. The; domain switching at different positions near the indentation crack tips; were in-situ observed by Raman spectroscopy. The variation of the peak; intensity of Raman soft modes of E(2TO) and E(3TO+2LO)+B1 versus the; observation point was analyzed. The results show that the electric; induced strain and 90° domain switching occurred at crack tips under the; external electric field. The peak intensity of Raman spectrum and soft; modes of E(2TO) and E(3TO+2LO)+B1 decreased with the distance between; observation point and crack tip increasing.国家自然科学基金资助项目; 福建省自然科学基金资助项