Abstract: Recent developments of piezocrystals, Li2B4O7, Sr3Ga2Ge4O14, LiNbO3 and LiTaO3 in our laboratory were reported in this paper. Li2B4O7 single crystals of 3 to 4 inches in diameter have been grown successfully by the modified vertical Bridgman method and mass production of large size Li2B4O7 crystals has been realized. Sr3Ga2Ge4O14 (SGG) crystal is a novel piezoelectric crystal with the largest piezoelectric constants among the langasite family. Bridgman growth of SGG crystal up to 2 inches in diameter has been reported and its piezoelectric properties have been measured. In order to improve the yield of SAW devices, pyro-free LiNbO3 and LiTaO3 wafers were prepared by chemical reduction at 700℃ and 450℃ respectively under a mixed atmosphere of CO2 and H2. Bridgman growth of LiNbO3 crystals was also investigated and some new phenomena were observed.

Key words: Recent developments of piezocrystals, Li2B4O7, Sr3Ga2Ge4O14, LiNbO3 and LiTaO3 in our laboratory were reported in this paper. Li2B4O7 single crystals of 3 to 4 inches in diameter have been grown successfully by the modified vertical Bridgman method and mass production of large size Li2B4O7 crystals has been realized. Sr3Ga2Ge4O14 (SGG) crystal is a novel piezoelectric crystal with the largest piezoelectric constants among the langasite family. Bridgman growth of SGG crystal up to 2 inches in diameter has been reported and its piezoelectric properties have been measured. In order to improve the yield of SAW devices, pyro-free LiNbO3 and LiTaO3 wafers were prepared by chemical reduction at 700℃ and 450℃ respectively under a mixed atmosphere of CO2 and H2. Bridgman growth of LiNbO3 crystals was also investigated and some new phenomena were observed.