Switching kinetics of 180 degrees domains in congruent LiNbO3 and LiTaO3 crystals

We present a systematic study of the switching and stabilization times of 1 80 degrees domains in congruent z-cut LiNbO3 and LiTaO3 crystals. The domai ns were reversed by the application of an electric field, and the kinetics studied for the first reversal of a virgin crystal (denoted as forward poli ng, or, f) and the second reversal back to its original state (denoted as r everse poling, or, r) at room temperature. The switching time, t shows an e xponential behavior with field as t = t(0)exp[delta/(E +/- E-int)], where t he - sign in the exponential is for forward poling, and - sign for reverse poling. The internal field, E-int, parallel to the ferroelectric polarizati on in a virgin crystal, was measured as 41.2 kV/cm for LiTaO3 and 22.2 kV/c m for LiNbO3. We also showed that there exists a minimum pulse width of the applied field below which the 180 degrees domains created by the field are unstable and show reversible wall motion. This stabilization time was meas ured as 1.4-2 s for LiTaO3 and only 10-30 ms for LiNbO3 in forward poling g eometry. We present evidence that the internal field and the domain stabili zation mechanisms are correlated. (C) 1998 Published by Elsevier Science Lt d.