Loss mechanisms in piezoelectric transducers and its response to stress

With the introduction of complex coefficients, the equivalent model of a piezoelectric transducer is established. Losses (elastic, piezoelectric and dielectric losses) or hysteresis in piezoelectrics are discussed in detail. The relationships of three dissipation factors (correspondent to three losses mentioned above) and equivalent circuit parameters are derived from the hysteresis theory and the piezoelectric equations. It is approved that the dissipation factors are dependant on complex coefficients and can be obtained through measuring the equivalent circuit parameters experimentally. When loaded by increasing stress, the piezoelectric transducer is monitored and the equivalent circuit parameters are measured. Dissipation factor vs. stress curves are plotted. With the theory that losses are considered to consist of four portions: domain wall motion; fundamental lattice portion; microstructure portion and conductivity portion, phenomenology of loss variations with stress is explained.