Growth and characterization of high temperature La3Nb0.5Ga5.3Al0.2O14 (LNGA) and La3Ta0.5Ga5.3Al0.2O14 (LTGA) piezoelectric single crystals

La3Nb0.5Ga5.3Al0.2O14 (LNGA) and La3Ta0.5Ga5.3Al0.2O14 (LTGA) single crystals were grown using the Czochralski method. Piezoelectric properties of LNGA and LTGA single crystals were measured and compared to La3Ga5SiO14 (LGS) crystals, where the piezoelectric coefficient d 11 and electromechanical coupling factor k 12 were found to be on the order of 6–7 pC/N and ∼16%, respectively. The resistivity of LNGA was found to be 1.1 × 10 8 Ω cm at 500 ∘C, much higher than those values of LTGA and LGS ( ∼ 2.2 × 10 7 Ω cm for LTGA and ∼ 9 × 10 6 Ω cm for LGS). The RC time constant of LNGA crystal was found to be 224 μs at 500 ∘C, while the values were 49 μs and 18 μs at the same temperature for LTGA and LGS, respectively. The good piezoelectric property, together with its high resistivity, exhibit LNGA single crystals a good candidate for piezoelectric applications at elevated temperature.