Domain reversal and nonstoichiometry in lithium tantalate

Recent studies have shown that lithium nonstoichiometry has a tremendous in fluence on domain reversal characteristics in ferroelectric lithium tantala te. This work presents a systematic study of the domain reversal characteri stics such as threshold coercive fields for domain reversal, domain stabili zation times, "backswitching" phenomena, domain switching and wall pinning times, and sideways wall mobility in near-stoichiometric LiTaO3 with Li/(Li +Ta)similar to0.498. These properties are contrasted with those of congruen t LiTaO3 [Li/(Li+Ta)similar to0.485]. A qualitative model is proposed based on nonstoichiometric dipolar defects to explain the dependence of threshol d coercive field on defect density, and on repeated field cycling, the orig in of domain backswitching, and domain stabilization times. (C) 2001 Americ an Institute of Physics.