NONLINEAR PIEZOELECTRICITY OF PZT CERAMICS AND ACOUSTIC PHASE-CONJUGATE WAVES

We succeeded in generating acoustic phase conjugate waves with nonline ar PZT (Pb(ZrxTi1-x)O-3) ceramics. The efficiency of the phase conjuga tor, which is defined as the amplitude ratio of the phase conjugate wa ve to the incident wave, is found to be proportional to the variation in sound velocity under an applied electric field. We measured the sou nd velocity in PZT ceramics with different compositions by varying the applied electric field. The results correlated well with the observed efficiency. The PZT ceramics are generally more capable than LiNbO3 c rystal of generating phase conjugate waves. We confirmed the time-reve rsal property of the phase conjugate waves by visualizing its propagat ion with the stroboscopic schlieren technique.