Growth and characterization of several piezoelectric crystals with an order langasite structure

STGS (Sr₃TaGa₃Si₂O₁₄), SNGS (Sr₃NbGa₃Si₂O₁₄), CTGS (Ca₃TaGa₃Si₂O₁₄) and CTAS (Ca₃TaAl₃Si₂O₁₄) were grown by using the Czochralski method. Selecting a suitable growth direction for the growth of large crystals is very important. STGS and CTGS is easily grown along the X-axis direction, and SNGS is easier to be grown along Y-axis direction than along X-axis direction. CTAS can be pulled along X-axis direction, but there was a serious opaque growth core defect. The measured piezoelectric stress coefficient and dielectric coefficient of crystals showed STGS, SNGS, CTGS and CNAS have similar piezoelectric performance, and the values of e₁₁ are about 2 times than that of the quartz. In addition, the cost of CTAS is lower than that of other three crystals, which make CTAS become a more promising piezoelectric material.