铌酸锂晶体铁电畴电极化反转结构的ESEM观察

Observation on the Electric Polarized Inversion Structure of Ferroelectric Domain in LiNbO_3 Crystal with ESEM

采用电脉冲极化方法制作出周期性反转电畴微结构。利用热腐蚀法制备出用于环境扫描电镜 (ESEM)研究反转电畴结构的样品。通过ESEM的观察与分析,在光栅电极下方,铁电畴发生了极化反转,反转区域在Y方向上有所扩展,在Z方向逐渐变窄,没能贯穿整个晶片。通过控制光栅电极的纵宽比和电压脉冲的参数,可以在晶片的表面或一定深度得到占空比为 1∶1的正、负铁电畴交替排列的结构,达到准相位配的目的。观测到竹叶状二次电子图像衬度,它是由制样过程中局部产生应力造成的,这说明利用ESEM可以研究压电材料中的电荷分布。

The microstructure of periodical reversal ferroelectric domain was produced by means of the electric impulse polarization. The samples used for examining the reversal domain with ESEM were prepared by heat erosion. ESEM observation and analysis show that the polarization reversal of the ferroelectric domain occurs under the grating electrode, the reverse regions spread in Y direction, get narrow in Z direction and did not penetrate the whole crystal plate. By controlling the length-width ratio of grating electrode and the parameters of potential pulse, the alternated structure of the positive and negative ferroelectric domains, with the duty ratio of 1:1, can be obtained on the crystal plate surface or in certain depth of the crystal, therefore the quasi-phase matching can be achieved. The pattern looking like bamboo leaves can be observed with ESEM, this kind of contrast is due to the local stress occurred in the sample preparation, so ESEM is capable of investigating the charge distribution in piezoelectric materials.