Using resonant ultrasound spectroscopy on samples with and without conducting coatings to measure piezoelectric constants

Abstract

Piezoelectrics are often used at low temperatures, but among the large number of piezoelectric materials, only one (quartz) has had its properties measured at low temperatures. Because measuring piezoelectric constants with the traditional electrical impedance method has shortcomings, particularly at liquid helium temperatures, it would be advantageous to make measurements with resonant ultrasound spectroscopy (RUS). EerNisse and Holland (1967) established a theoretical basis and Ogi et al. (2002) demonstrated an experimental RUS method. A problem with RUS for piezoelectrics is that resonance frequencies are much more sensitive to elastic behavior than to piezoelectric behavior, so that extraordinary precision is required. However, one may make a RUS measurement on a sample twice, once with an electrically conducting coating on sample faces and once without, and analyze the differences in the frequency spectra. Because the effect of the conducting coating depends more on the piezoelectric behavior than on the elastic behavior, analyzing the frequency differences suppresses the dependence on the elastic constants and enhances the measurement of the piezoelectric constants. This paper will present theoretical and experimental results for this RUS method.