Piezo electric crystal
Development of high-temperature piezoelectric devices using Langasite (La3Ga5SiO14) -type single crystals
The application temperature of current piezoelectric devices is limited by the intrinsic properties of the piezoelectric materials. Materials which exhibit attractive room temperature piezoelectric properties either decompose (e.g. LiNbO3 at 300°C) or exhibit phase transformations (e.g. Li2B4O7 at approximately 500°C) at elevated temperatures. The highest current application temperature of about 450°C is reached by quartz resonators above which high losses and phase transformations prevent its use.
A promising candidate materials for piezoelectric applications at high temperatures are langasite (La3Ga5SiO14). Langasite does not undergo phase transformations up to the melting temperature of 1470°C. Due to langasite｡ｯs high phase transformation temperature and the availability of high quality crystals, this material is of particular interest. Previous investigations confirmed that langasite may be operated as a BAW resonator up to temperatures of at least 750°C.