Correlation of BAW and SAW properties of langasite at elevated temperatures

Abstract

Abstract. The full set of electromechanical data of langasite (La 3 Ga 5 SiO 14 ) is determined in the temperature range from 20 to 900 • C using differently oriented bulk acoustic wave resonators. For data evaluation a physical model of vibration is developed and applied. Thereby, special emphasis is taken on mechanical and electrical losses at high temperatures. The resulting data set is used to calculate the properties of surface acoustic waves. Direct comparison with experimental data such as velocity, coupling coefficients and propagation loss measured using surface acoustic wave devices with two different crystal orientations shows good agreement.

Mode Analysis of Pt/LGS Surface Acoustic Wave Devices

“…From Table 1 , it is seen that the calculated and obtained by numerical computation and 3D COMSOL simulation are in excellent agreement, and they also agree well with the reported values [ 11 , 29 , 30 ]. However, there is a significant discrepancy between the values calculated by 2D COMSOL simulation and by the other two methods.…”

“…The dispersion relation between acoustic velocity and indicates that both and can be used to control the acoustic velocity, hence the resonant frequency of devices. Some previous works reported that, from room temperature upwards, LGS (0 , 138.5 , 27 ) SAW device has a monotonous frequency-temperature characteristic, while LGS (0 , 138.5 , 117 ) SAW device features a non-monotonic temperature characteristic, with a relatively larger strain sensitivity than the former [ 10 , 11 , 36 ]. However, these results all refer to the Rayleigh mode of the LGS SAW devices.…”

“…In recent years, a large number of studies on Pt LGS SAW devices have published, and many attractive applications have been explored, among which wireless passive sensing in harsh environments was extensively investigated. Schulz et al presented the temperature performance of Pt LGS SAW device up to 800 °C [ 10 , 11 , 12 ]; Maskay et al developed a Pt-alloy-based LGS SAW device for strain sensing [ 13 ]; Thiele et al reported on the gas sensing performance of Pt LGS SAW devices up to 750 °C [ 14 ]. In hostile environments such as gas turbines [ 15 ], high temperature, high pressure and large strain often coexist, and monitoring these parameters is very crucial for machine state monitoring and structure health maintenance.…”