Langasite for high-temperature bulk acoustic wave applications

Langasite (La3Ga5SiO14) and related compounds are promising candidates for high-temperature piezoelectric applications. To determine the stable operation of langasite as a high-temperature bulk acoustic wave (BAW) resonator, we characterized electrical conductivity [sigma (el)=1.56xexp(-1.07 eV/kT)S/cm] and oxygen diffusivity [D-ox(T)=5x10(-5) exp(-1.45 eV/kT)cm(2)/s] up to elevated temperatures. Langasite was successfully operated up to 900 degreesC as a BAW resonator with an average mass sensitivity of about 0.17 mug Hz(-1) cm(-2). This enables, in principle, high-temperature monitoring of deposition rates and thermogravimetry with high sensitivity. (C) 2001 American Institute of Physics.