Lateral electric field excited resonator based on PZT ceramics

Abstract

At present lateral electric field excited piezoelectric resonators widely used for development of various sensors. Previously we have studied the resonator based on the plate of lithium niobate operating in the frequency range 6 – 7 MHz. This resonator demonstrated high value of Q - factor but required the special measures for suppression of parasitic oscillations. In this paper the lateral electric field excited piezoelectric resonators based on ceramics (PZT-19) were developed. The characteristics of these resonators were calculated with the help of finite element analysis (FEA) that allowed to determine the distribution of the components of mechanical displacement in piezoelectric plate and electric field intensity in the plate and surrounding vacuum. This method allowed to consider the different boundary conditions on the different parts of plate surface and acoustical attenuation due to imperfection of piezoelectric ceramics. We calculated the frequency dependence of electrical impedance of the resonator near the resonance on the first harmonics. The resonator under study represented the plate with thickness of 2 mm and shear dimensions 18 × 20 mm. As a material we used the prevalent in Russia piezoceramics of PZT - 19. We studied three resonators with the width of the gap between electrodes of 2, 3, and 4 mm. The electrodes were deposited in such a way that exciting electric field was oriented along the crystallographic axis Z of ceramics. It was been found that the resonator of such design had the value of Q - factor of 180 on the resonant frequency ∼100 kHz without any special measures for suppression of unwanted oscillations. The obtained theoretical results are in a good agreement with experimental data.