Temperature-Dependent Characteristics of Surface Acoustic Wave Resonators Deposited on (0°, 138.5°, $\psi$ ) Langasite Cuts

Surface acoustic wave (SAW) resonators were deposited on (0°, 138.5°, $\psi $ ) LGS (langasite, La 3 Ga 5 SiO 14 ) cuts with different Euler angles $\psi $ in this paper. The temperature-dependent characteristics of these SAW resonators were investigated systematically. At room temperature, the (0°, 138.5°, 26.6°) LGS cut has the maximum SAW velocity of about 2716 m/s. The (0°, 138.5°, 3.4°) LGS cut has the minimum SAW velocity of about 2377 m/s. The first-order and second-order temperature coefficients of frequency in the (0°, 138.5°, 26.6°) and (0°, 138.5°, 33.4°) LGS cuts are nearest to zero. The turnover temperature decreases first when the angle $\psi $ varies from 3.4° to 26.6° and increases with the further increase of $\psi $ . The results in this paper may help us design LGS SAW temperature sensors and other types of sensors.