Investigation of structural, thermal and high-temperature piezoelectric properties of Ca3Ta(Ga1−xAlx)3Si2O14 crystals grown by the vertical Bridgman method

Abstract

Ca₃Ta(Ga_1−xAl_x)₃Si₂O₁₄ (CTGAS) has emerged as a promising high-temperature piezoelectric material within the langasite family. However, conventional growth using the Czochralski method is associated with high manufacturing costs. In this work, CTGAS crystals with varying Al³⁺ doping concentrations (x = 0, 0.25, 0.5) were successfully grown using the more economical vertical Bridgman (VB) method. The structural, thermal, optical, and piezoelectric properties of the as-grown crystals were systematically investigated and compared. The results show that the as-grown CTGAS crystals exhibit good crystalline quality, high optical transparency, and favorable thermal characteristics. Notably, all samples maintain high resistivity at elevated temperatures, exceeding 10⁶ Ω cm at 800 °C. In addition, the crystals maintain stable piezoelectric performance and relatively high thermal conductivity. These results indicate that CTGAS crystals grown by the VB method combine cost efficiency with reliable high-temperature functional properties, making them promising candidates for high-temperature piezoelectric sensing applications.