Evaluation of the Accuracy in Determining the Mechanical Quality Factor for Piezoceramic Resonators

Abstract

Accuracies of three methods used to determine the mechanical quality factors of piezoceramic resonators were evaluated and discussed for the specific case of five materials with different mechanical quality factors (between 20 and 3000) and electromechanical coupling coefficients (between 2.5% and 60%). The mechanical quality factor Q m was calculated for both radial and thickness modes. The three methods are: the equivalent circuit, the band width and the iterative method. The last two methods proved to be very accurate for all materials (the error of Q m is less than 0.1%), but for low Q m materials the second method requires to redefine the involved frequencies. The first method is less accurate, especially for materials with low mechanical quality and electromechanical coupling factors or large difference between the mechanical quality factors of the resonance and antiresonance bands (the error of Q m is more than 10–20%).