Growth and high-temperature electromechanical properties of Ca₃ NbX₃ Si₂ O₁₄ (X = Ga and Al) piezoelectric crystals

Piezoelectric single crystals of Ca₃NbX₃Si₂O₁₄ (CNXS, X=Ga and Al) with ordered langasite structure were successfully grown using the Czochralski technique. The structure was analyzed by X-ray powder diffraction, and the lattice parameters for CNAS were found to decrease slightly when compared to CNGS, due to the smaller ion radius of Al. The dielectric, piezoelectric and electromechanical properties were studied as function of temperature from 30 ^{{ring operator}}C to 900 ^{{ring operator}}C, showing a stable temperature-dependent behavior. Of particular significant is their high mechanical quality factor and electrical resistivity at elevated temperature, demonstrating CNXS crystals to be promising candidates for high-temperature applications.