Langasite for high-temperature acoustic wave gas sensors

Langasite (La3Ga5SiO14), a piezoelectric material with no phase transitions to 1470 °C, holds promise as a high-sensitivity crystal microbalance gas sensor platform. In order to successfully implement langasite acoustic wave gas sensors, electrical losses at elevated temperatures need be minimized. The electrical conductivity of langasite is characterized as a function of oxygen partial pressure for temperatures of 700–1000 °C and correlated with the decrease in Q with increasing temperature. These results are used to define the operating limits for acoustic wave gas sensors based on langasite.