METHOD OF PRODUCING SUBSTRATE FOR PIEZOELECTRIC DEVICE, SUBSTRATE FOR PIEZOELECTRIC DEVICE AND SURFACE ACOUSTIC WAVE DEVICE USING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a method of producing a substrate for a piezoelectric device, by which a crystal free from occurrence of a secondary phase and having a uniform composition can be obtained, and to provide the substrate for the piezoelectric device and a surface acoustic wave device obtained by using the same. SOLUTION: The method of producing the substrate for the piezoelectric device comprises growing a La3Ga5SiO14 single crystal and processing the single crystal into the substrate for the piezoelectric device. The La3Ga5SiO14 single crystal is obtained by weighing La2O3, Ga2O3 and SiO2 each in an amount in the composition range surrounded by points A (La2O3:47.98 wt.%, Ga2O3:46.32 wt.% and SiO2:5.70 wt.%), B (La2O3:48.50 wt.%, Ga2O3:46.32 wt.% and SiO2:5.18 wt.%), C (La2O3:48.50 wt.%, Ga2O3:47.50 wt.% and SiO2:4.00 wt.%), D (La2O3:47.50 wt.%, Ga2O3:47.50 wt.% and SiO2:5.00 wt.%), E (La2O3:47.50 wt.%, Ga2O3:46.32 wt.% and SiO2:6.18 wt.%), F (La2O3:47.50 wt.%, Ga2O3:46.00 wt.% and SiO2:6.50 wt.%) and G (La2O3:47.98 wt.%, Ga2O3:46.00 wt.% and SiO2:6.02 wt.%), as shown in Fig.1, then melting the components in a crucible and pulling and growing the single crystal expressed by the formula: La3Ga5SiO14 is formed inside the crucible.