Crystal structure and piezoelectric properties of four component langasite A 3B Ga 3Si 2O 14 (A = Ca or Sr, B = Ta or Nb)

Abstract

As langasite A 3BC 3D 2O 14 compounds with piezoelectric properties exhibit no phase transition up to the melting point of 1,400-1,500°C, many high temperature applications are expected for the SAW filter, temperature sensor, pressure sensor, and so on, based on the digital transformation of wider bandwidth and higher-bit rates. It has a larger electromechanical coupling factor compared to quartz and also nearly the same temperature stability as quartz. The La 3Ga 5SiO 14 (LGS) crystal with the Ca 3Ga 2Ge 4O 14-type crystal structure was synthesized and the crystal structure was analyzed by Mill et al. It is also an important feature that the growth of the single crystal is easy. In the case of threeelement compounds such as [R 3] A[Ga] B[Ga 3] C[GaSi] DO 14 (R=La, Pr and Nd), the piezoelectric constant increases with the ionic radius of R. In this study, crystal structures of four-element compounds such as [A 3] A[B] B[Ga 3] C [Si 2]DO 14 (A = Ca or Sr, B = Ta or Nb) are analyzed by a single crystal X-ray diffraction, and the mechanism and properties of the piezoelectricity depending on the species of cation was clarified based on the crystal structure. © 2012 KIEEME. All rights reserved.