A defect coefficient - new insight into the responses of piezoelectric quartz crystal in gaseous and liquid phases

A defect coefficient (d), defined as the ratio of an electromechanical coup ling factor in liquid phase (K-L(2)) to that in gaseous phase (K-g(2)) has been proposed and applied to investigate the responses of a piezoelectric q uartz crystal in gaseous and liquid phases. On the basis of an electromecha nical equivalent circuit model, the value of d is calculated to be 1/2 and the explicit expression of K-L(2) is then given. According to electromechan ical analogy, both sides of the expression L = m/k(2) are suggested to be d ivided into three terms when the crystal contacts with liquid. In this case , the corresponding expressions of k(2) can also be obtained. By using K-L( 2), R-1 given by Muramatsu is found to be root2 times as large as R-2 given by Martin, and this relationship is experimentally evaluated. Furthermore, the phenomenon that the crystal with a lower fundamental frequency (f(0)) gives larger response of R1 than the crystal with a higher f(0) is rational ly explained. (C) 2001 Elsevier Science B.V. All rights reserved.