R3Ga5SiO14 (RGS, R: rare-earth elements) and RCa4O(BO3)3 (RCOB) single crystals were synthesized by the Czochralski technique and their piezoelectric properties were investigated. The piezoelectric moduli, d11 and d14, of La3Ga5SiO14 are higher than those of Nd 3Ga5SiO14. Moreover, in the RGS-type crystal, we found that the piezoelectric modulus, d11, increased with the lattice parameter a. The ionic size preferences of all cation sites in the RGS-type structure were also clarified. Based on these results, a new RGS-type Ba3TaGa3Si2O14 crystal was synthesized. We have successfully grown RCOB (R = La, Nd, Gd, Dy, and Y) single crystals with 1 and 2 in. diameter dimensions. The surface acoustic wave (SAW) properties of RCOB filters were investigated. In RCOB, the NdCOB single crystal showed the highest electromechanical coupling factors and lowest temperature coefficient of delay of the RCOB crystals.
- Crystal growth
- Rare-earth element