Piezoelectric cross-talk investigation of LGT and CTGS single crystlals

Among langasite type crystals, La₃Ga_5.5Ta_0.5O₁₄ (LGT) and Ca₃TaGa₃Si₂O₁₄ (CTGS) possess relatively high resistivity (>10⁶Ωcm@600°C) and high effective piezoelectric coefficient (6-8 pC/N) at elevated temperatures, exhibited the potential use for high temperature sensing. In this work, the maximum piezoelectric coefficients and piezoelectric cross-talk behaviors for LGT and CTGS crystals are investigated, where the maximum piezoelectric d₁₁, d₁₄ and d₂₆ for LGT crystals are obtained to be on the order of 7.2, 9.7 and 14.7 pC/N, respectively, while for CTGS crystals, the maximum d₁₁, d₁₄ and d₂₆ are found to be 4.6, 12.2, and 11.4 pC/N, respectively. Of particular significance is that the optimum crystal cuts free of cross-talk were obtained from LGT and CTGS crystals, with effective piezoelectric coefficients being on the order of 14-15 pC/N and 8-11 pC/N, respectively, attractive for high temperature piezoelectric applications.