Growth and piezoelectric properties of large sized Ca3TaGa3Si2O14 crystals

Abstract

Ca₃TaGa₃Si₂O₁₄ (CTGS) crystals are excellent high temperature piezoelectric materials. 4–6 inch CTGS crystals were successfully grown by the Czochralski method. The (110), (100) and (001) faces were strongly exposed, respectively, and the growth rate of the (001) faces was obviously faster than those of (100) and (110). The full width at half-maximum (FWHM) values of a 4 inch Y-cut CTGS wafer were found to be between 11.8′′ and 15.8′′. The piezoelectric properties of CTGS were measured by the resonance method at room temperature. The piezoelectric coefficients d₁₁ and d₁₄ were found to be 4.07 pC N⁻¹ and −14.01 pC N⁻¹, and the electromechanical coupling coefficients k₁₂ and k₂₆ were determined to be 24.7% and 19.5%, respectively. All d₁₁ values of X-cut plates cut from different positions of the as-grown crystal were determined to be between 4.1 pC N⁻¹ and 4.3 pC N⁻¹. The electrical resistivities of the X-cut plates of CTGS were approximately 7.1 × 10⁸ Ω cm at 500 °C and 4.4 × 10⁶ Ω cm at 800 °C, respectively.