Growth of a 3 '' langasite crystal with clear faceting

A macrodefect-free langasite (La3Ga5SiO14) crystal 3 " in diameter was grow th along its Z-axis by the Czochralski technique. The grown crystal showed clear faceting on (0001) and (01 (1) over bar 0) faces, forming a hexagonal column shape, and it had minor faceting on (01 (1) over bar 1) in the coni cal part, making a stepped hexagonal pyramid. Thermal treatment of the melt and uniform interface shape are important to the growth of langasite with stable facet development. Interface instability occurred during the formati on of the conical portion of the crystal under a high crystal rotation rate . The homogeneity in composition was investigated two dimensionally by the X-ray Bond diffraction method. The congruent melt composition for langasite is also discussed relative to the stoichiometric composition. (C) 2000 Els evier Science B.V. All rights reserved.