Crystal growth of Ca3Nb(Ga1-xAlx)3Si2O14 piezoelectric single crystals with various al concentrations

Abstract

Ca3Nb(Ga1-xAlx)3Si2O14 (CNGAS) single crystals with various Al concentrations were grown by a micro-pulling-down (μ-PD) method and their crystal structures, chemical compositions, crystallinities were investigated. CNGAS crystals with x = 0.2, 0.4 and 0.6 indicated a single phase of langasite-type structure without any secondary phases. In contrast, the crystals with x = 0.8 and 1 included some secondary phases in addition to the langasite-type phase. Lattice parameters, a- and c-axes lengths, of the langasite-type phase systematically decreased with an increase of Al concentration. The results of chemical composition analysis revealed that the actual Al concentrations in as-grown crystals were almost consistent with the nominal compositions. In addition, there was no large segregation of each cation along the growth direction.