Characterization of piezoelectric single crystal YCa4O(BO3)3 for high temperature applications

Operation at temperatures well above ambient is desired for applications such as smart structures integrated within aircraft and space vehicles. Piezoelectric yttrium calcium oxyborate single crystal YCa4O(BO3)3 (YCOB) was found to exhibit no phase transition until its melting temperature around ∼1500°C. The temperature characteristics of the resonance frequency, electromechanical coupling, and dielectric permittivity were studied in the temperature range of 30–950°C for different orientations. The electrical resistivity at 800°C was found to be greater than 2×108Ωcm. Together with its temperature independent electromechanical coupling factor (∼12%) and engineered resonance frequency behavior, these make YCOB crystals excellent candidates for sensing applications at ultra high temperatures.