Comparison among Three Measurement Methods of the Nonlinear Piezoelectric Coefficient of a Third-Higher Term in Lead Zirconate Titanate Piezoelectric Ceramics

An effective 3rd nonlinear piezoelectric coefficient for a vibrator in a piezoelectric ceramic with a rectangular shape was measured using a constant-current circuit. On the base of the nonlinear piezoelectric equation, we applied three different measurement methods: (1) the change of the resonance frequency with increasing sample current; (2) the change of magnitude of nonlinear fundamental voltage; (3) the change of magnitude of the 3rd harmonic voltage. The methods were evaluated and compared with respect to their simplicity and accuracy.