Poling induced higher order nonlinearity changes in lead zirconate titanate ceramic

High order nonlinear behaviors in Pb(Zr1−x,Tix)O3 (PZT) ceramics were studied using the harmonic generation technique, both before and after poling. It was found that the amplitude of the third harmonic is smaller than that of the second harmonic before poling, but the situation is reversed after poling with a substantial increase of the third harmonic amplitude. Noticeable time dependence of nonlinearities were observed in poled ceramics, which gradually decreased and saturated after about two days. These facts confirmed the generation of microcracks during poling.