Quartz and GaPO4 pressure transducers for high resolution applications in high temperature: A simulation approach

An accurate computer model was created for the extraction of the quality factor, Q, and the sensitivity of piezoelectric pressure transducer. The quality factor is a key parameter to determine the transducer resolution. The effect of viscosity loss and geometrical factors, such as: thickness, diameter, and concavity (plano-convex and bi-convex) are simulated in AT-cut quartz and Hi-Q cut gallium phosphate (GaPO₄) materials. AT-cut quartz is a standard material in this type of application, and gallium phosphate is a promising material for advanced pressure transducer. The goal is to evaluate device specifications to achieve the highest Q-factor (Q > 10⁶) at frequencies up to 10 MHz. Temperature dependent elastic constants and boundary load conditions are used to simulate temperature and hydrostatic pressure effects on the vibrating transducer. The frequency shift is simulated in the range of 25 °C to 200 °C and 14.7 psi to 20,000 psi for temperature and pressure, respectively. The simulation results allows for a resolution of 1 psi for a frequency resolution of 1 ppm. All simulations are carried out with COMSOL Multiphysics software, version 4.4.