High power piezoelectric characterization system (HiPoCS™)

Abstract

The bottleneck of the piezoelectric devices in miniaturization is the heat generation owing to the losses. There are three losses in a piezoelectric material; dielectric, elastic and piezoelectric losses. The development of high-power density piezoelectrics is directly relevant to the clarification of the loss mechanisms in such materials. This article describes the characterization methodologies of high-power piezoelectrics, in particular, in determining the three losses separately. There are two categories for the measuring methods: (1) electrical excitation method, and (2) mechanical excitation method. The former is basically admittance/impedance measurement via the output current over the input voltage, further classified into four methods; (a) constant voltage, (b) constant current, (c) constant vibration velocity, and (d) constant input energy. To the contrary, the latter is basically the transient mechanical vibration ring-down measurement under various electrical constraint conditions. The key is to obtain precise values of both mechanical quality factors at resonance Q A and at antiresonance Q B , regardless of measuring techniques, so that we can determine the piezoelectric loss precisely. The difference of Q M between the resonance and antiresonance is originated from the electromechanical coupling factor k 2 loss, k 2 00 k 2 0 ¼ ð2 tan h 0 À tan d 0 À tan / 0 Þ: Depending on the sign of the k 2 loss, more efficient driving frequency can be derived rather than the conventional 'resonance' frequency.

Loss Determination Techniques for Piezoelectrics: A Review

“…In the following subsubsections, these two types of high-power measurement methods, mainly proposed by our research group, will be discussed. The readers may refer to the review [64] for more information regarding the method described in the next subsubsections.…”