Piezoelectric properties of (Sr0.2Ca0.8)3TaGa3Si2O14 and Ca3TaGa3Si2O14 single crystals grown via vertical Bridgman method

Abstract

CTGS crystals are widely used in the field of high-temperature piezoelectricity because of their excellent piezoelectric properties. In this paper, the Ca²⁺ lattice of CTGS crystals is replaced by Sr²⁺ with a larger radius to improve their piezoelectric properties. (Sr_0.2Ca_0.8)₃TaGa₃Si₂O₁₄ and Ca₃TaGa₃Si₂O₁₄ single crystals with a diameter of 25 mm were grown using the vertical Bridgman method. The full width at half maximum (FWHM) of X-ray rocking curves of SCTGS and CTGS crystals are 57.6′′ and 22.3′′, respectively. It was found that the thermal properties of SCTGS crystals, such as specific heat, thermal diffusion and thermal conduction, are slightly lower than those of CTGS crystals. At room temperature, the dielectric permittivity ε^T₁₁ increased from 18.59 to 18.78, and the piezoelectric coefficient d₁₁ also increased from 4.22 pC N⁻¹ to 4.54 pC N⁻¹. The electrical resistivities of the X-cut plates of SCTGS and CTGS crystals are approximately 3.78 × 10⁷ Ω cm and 2.40 × 10⁷ Ω cm at 800 °C, respectively. Therefore, SCTGS will be a promising candidate piezoelectric material in the field of high-temperature sensing.