High-temperature electromechanical loss in piezoelectric langasite and catangasite crystals

Temperature-dependent acoustic loss Q−1 is studied in partially disordered langasite (LGS, La3Ga5SiO14) and ordered catangasite (CTGS, Ca3TaGa3Si2O14) crystals compared with previously reported CTGS langatate (LGT, La3Ga5.5Ta0.5O14) data. Two independent techniques, a contactless tone-burst excitation technique contacting resonant piezoelectric spectroscopy, are used this study. Contributions to the measured Q−1(T) determined through fitting physics-based functions, extracted fit parameters, including activation energies of processes, discussed. It shown that losses LGS caused by superposition several mechanisms, intrinsic phonon–phonon loss, point-defect relaxations, conductivity-related relaxations.