Investigation of the electrode coating influence on the frequency temperature characteristics of the resonators operating at the rotated Y-cut Ca3TaGa3Si2O14 single crystals

Resonators manufactured on Ca₃TaGa₃Si₂O₁₄ single crystals (CTGS) operating in a thickness shear mode were investigated. The frequency temperature characteristics of the rotated Y-cut based resonators were measured. The resonators operated at the crystal elements with angle cut -21°20´ have frequency deviation less than 120 ppm in the operating temperature range from -60 up to 85°C. The temperature coefficient of frequency of the second order is close to -0.022 ppm/°C². It is shown that maintaining turnover point of the frequency temperature characteristic within the range of ±1 °C requires accuracy of the crystal element manufacturing not worse than ±1.5 angular minutes for resonators with Ag electrodes. The dependence of the Bechmann´s number on electrode thickness was calculated. It was discovered that for Ag electrode coating with electrode thickness of 200 nm, the single-response characteristic of the resonator can be obtained if the electrode size (l_x) does not exceed 12 thicknesses of the crystal element. With the limiting value of the relative electrode size equaling l_x/t =12.3, the relative resonance interval is 1%, while the capacitance ratio is 47 units.