Shape-controlled langasite-type piezoelectric single crystals have been developed by the micro-pulling-down (μ-PD) method using specially designed Pt-Rh-Au crucibles with suitable wetting to the melt of langasite-type materials. The shape-controlled langasite-type piezoelectric single crystals indicated the comparable piezoelectric properties to the crystals grown by the conventional methods.
Ca3Nb(Ga1-xAlx)3Si2O14 (CNGAS) and Ca3Ta(Ga1-xAlx)3Si2O14 (CTGAS) single crystals have been developed and the effects of Al substitution on their crystal growth, phase formation and piezoelectric properties were revealed. CNGAS and CTGAS single crystals could be grown by the μ-PD method in the range of 0 ≤ x ≤ 0.6 and 0 ≤ x ≤ 1, respectively. Piezoelectric properties of the CNGAS and CTGAS bulk single crystals grown by the Czochralski (Cz) method were investigated, and the piezoelectric constant d11 and electromechanical coupling factor k12 were increased by the Al substitution. In addition, the precise material constants of the CNGAS and CTGAS single crystals have been clarified by the ultrasonic material characterization system, and the 2 inch bulk single crystals have been developed by the Cz method.
