Growth of a 3 inches langasite crystal with clear faceting

A macrodefect-free langasite (La₃Ga₅SiO₁₄) crystal 3 inches in diameter was grown along its Z-axis by the Czochralski technique. The grown crystal showed clear faceting on (0001) and (011̄0) faces, forming a hexagonal column shape, and it had minor faceting on (011̄1) in the conical 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 formation 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.