A comparison of surface transverse wave propagation on quartz and gallium orthophosphate

Gallium orthophosphate (GaPO4) is a piezoelectric material (32‐class) with the same symmetry as quartz, but with a higher electromechanical coupling factor and richer possibilities of temperature‐compensated acoustic modes in a wide range of temperatures, mainly at high temperatures above 300 °C. Surface transverse waves (STWs) can be generated on both quartz and GaPO4 crystals on Y‐rotated plates, so it is interesting to compare both materials on this respect. It is shown that a temperature‐compensated orientation exists on GaPO4 for STWs, but with a lower velocity (2500 m/s) than for quartz (5100 m/s). Propagation of STWs on GaPO4 under an array of metal strips or grooves is studied and dispersion curves for grooves, aluminum, and gold strips are presented. It is shown that energy trapping near the surface will occur in all cases, allowing STW resonators to be built on GaPO4. The sensitivity of STW devices on GaPO4 to metal thickness and geometrical parameters of electrodes will be investigated. Poss...