Electro-Elastic Features of Ga3PO7 Crystal at Elevated Temperature

High-temperature piezoelectric materials with good temperature stability are essential for various sensors fabrication. In this study, the temperature stability of electro-elastic coefficients of Ga3PO7 crystal was studied by using the impedance method. Results reveal that the Ga3PO7 maintained a value on the order of 10⁷ Ω•cm at 800°C, with resistivity along the crystallographic Z-axis slightly exceeding that along the X-axis. Within the temperature range of 50-850°C, the dielectric permittivity demonstrates a gradual increase with rising temperature. Dielectric losses exhibit minimal variation between 50°C and 500°C, beyond which a significant increase is observed. The elastic compliance constants $s_{22}^E$ and $s_{55}^E$ undergo a linear, slow increase with temperature, showing relative changes of +9.54% and +9.16%, respectively. The piezoelectric coefficients show distinct temperature dependencies: d22 varies by -8.33% to +4.17%, while d31 and d15 increase slowly, remaining within variations of +11.56% and +7.06%, respectively, across the temperature range of 50-850°C. Totally, the extremely high resistivity and low temperature coefficient of piezoelectric coefficient indicates the potential usage of Ga3PO7 crystal for piezoelectric devices over a wide temperature range.