METHOD OF GROWING SHAPED CRYSTALS OF REFRACTORY COMPOUNDS Russian patent published in 2001 - IPC

FIELD: growing crystals of preset shape from melt, particularly, crystals of refractory compounds, for instance, leucosupphire, rubin, aluminothorium garnet, etc; applicable in instrumentation engineering, electronic and chemical industries. SUBSTANCE: method of growing shaped crystals of refractory compounds from melt on end face of shaping device is realized by loading of initial raw materials into crucible; evaluation of system to residual pressure of not more than 1·10^-5 mm Hg; firing in inert atmosphere at temperature of 1550-1650 C; repeated evacuation of system to residual pressure of not in excess of 1·10^-3 mm Hg; raising of temperature in inert atmosphere up to melting of initial raw materials; immersion of shaping device into melt through 0.45-0.60 of its height; filling of melt into capillary system of shaping device; formation on end face of shaping device of melt film with an angle of inclination of its side surfaces equalling 40-65 deg to crystal longitudinal axis; provision of contact of melt with seed; heating and fusing of seed; growth and pulling of crystals at speed of 0.2-0.8 mm/min with overheating of melt relative to their crystallization temperature; break-off of crystal with increase of growth within interval of 0.8-5 mm/min and cooling of grown crystal. EFFECT: higher yield of serviceable crystals according to their optical characteristics. 5 cl, 1 tbl