CTGS material parameters obtained by versatile SAW measurements

Abstract

Recently big size high quality piezoelectric single crystals of Ca3TaGa3Si2O14 (CTGS) have been grown. This temperature durable crystal is very promising for future application in different devices based on surface acoustic waves (SAW) due to its high electromechanical coupling compared to quartz. In contrast to the popular langasite, CTGS is a more ordered compound and therefore stands for better characteristics at both, high temperatures and high frequencies. During the last decade several sets of material constants for CTGS were published extracted from bulk acoustic wave measurements on small samples, but these results are strongly different from each other. Moreover, all published constant sets lead to unacceptable numerical differences for calculated SAW velocities when compared to recent measurements of SAW velocities on large CTGS wafers. In this work we present a new set of room temperature CTGS material constants, extracted by combination of high-precision SAW phase velocity measurements with proprietary numerical procedures developed in-house.