Frequency-temperature characteristics of the langasite resonators

This paper presents the results of the theoretical and experimental investigations on frequency-temperature characteristics of plane-parallel Y-cut langasite resonators for various mass-loading conditions. Circular Sawyer Y-cut langasite blanks with 14 mm diameter, Au electrodes with 7 mm diameter and various thicknesses were used in experiments. The resonance frequencies were measured in the temperature range from -35°C to +100°C. First, second and third order of the frequency-temperature coefficients were computed for the fundamental, third and fifth overtones. The electromechanical coupling factors were computed from measured fundamental and third harmonic resonance frequencies. The dependence of the turnover temperatures at the fundamental, third and fifth overtones of the thickness-shear vibrations with the orientation angle of the cut YX1_α was also calculated. The results allow to adjust a desired turnover temperature in accordance with a specific application, and reveal that the influence of the mass-loading on frequency-temperature characteristics of Y-cut langasite resonators is lower than in the case of AT-cut quartz resonators