Journal of the acoustical society of america vol:99 issue:3 pages:1430-1437
Frequency dependence of the first ultrasonic nonlinear parameter and the abnormally high third harmonic signals measured in lead zirconate-titanate (PZT) ceramics suggest the introduction of a revised theoretical model combining higher-order nonlinearity and generalized dispersion. The new nonlinear dispersive equation has been solved by perturbation theory. A solution is found in the form of a set of parameters whose magnitude is obtained from a fit of the experimental data. The parameters are independent of frequency and initial amplitude. The model is applied to four samples, and the results are discussed. The validity of the perturbation theory in these cases is tested. (C) 1996 Acoustical Society of America.