Operation limits of langasite high temperature nanobalances

The high temperature properties of langasite (La3Ga5SiO14) are presented in order to evaluate its ability to serve as a high temperature nanobalance. Langasite resonators exhibit bulk oscillations at temperatures of up to 900°C. At 800°C, the mass load response for 780 μm thick resonators is approximately −6.5 cm2 Hz μg−1. The temperature dependent frequency shift, about −100 Hz K−1 at 600°C, may be effectively compensated by monitoring the difference frequency of closely mounted resonators. As an example, the response of a TiO2−x coated langasite nanobalance to different oxygen partial pressures at elevated temperatures is presented. The strong frequency shift due to switching from oxidizing to reducing conditions cannot be attributed to mass changes of the sensor film. Mechanical stress caused by changes in the oxygen stoichiometry is the most likely explanation for the frequency changes.