Abstract: An apparatus for growing shaped single crystals of high-melting transparent metal compounds has a sealed chamber (1) having inside thereof a heat insulating unit (2) with a heater (3) in the form of a sleeve accommodating a crucible (5), mounted for axial reciprocations in the sleeve a shape-imparting member (6) in the form of a cylinder having capillary orifices for supplying a melt (11) from the crucible (5) to a crystallization zone (14) of a single crystal (7) located above an upper end (13) of the shape-imparting member (6) which is configured to have a cross-sectional shape of the single crystal (7). The heater also accommodates horizontally extending planar thermal shields (23) having coaxial openings (25) for the single crystal (7) being grown to pass therethrough, and a thermal shield (24) in the form of a hollow cylinder mounted in the openings of the planar thermal shields.

Abstract: A process for growing shaped single crystals of refractory optically transparent metal compounds comprising melting a starting stock in an inert gas atmosphere under the effect of heat evolved by a heater; the melt is continuously fed into a crystallization zone through a capillary system of a shaping unit, followed by pulling a single crystal from the crystallization zone and cooling thereof. Prior to melting of the starting stock one control particle thereof is placed into the crystallization zone and at the moment of melting of said particle the heater power P is recorded. Melting of the starting stock is conducted at a heater power of (1.04-1.1)P, fusing of the seed--at a power of (1.03-1.08)P, building-up of the single crystal--at a power of (1.02-1.08)P; pulling--at a power of (1.02-1.22)P.

Abstract: During the process of pulling sapphire tubes from a melt with the aid of a seed, the longitudinal temperature gradient in the zone between the solidified front and the region of pulling where the temperature is between 1850 and 1900 deg. C. is maintained not in excess of 30 deg. C./cm. The tube so grown is annealed at a temperature between 1950 and 2000 deg. C. by increasing the temperature at a rate of 30 to 40 deg. C./min and keeping the tube at said temperature during a period between 3 and 4 hours. After that the tube is cooled down to room temperature at a rate of 30-40 deg. C./min.Disclosed is also an apparatus which enables said temperature gradient to be maintained while pulling the tube.

Abstract: During the process of pulling sapphire tubes from a melt with the aid of a seed, the longitudinal temperature gradient in the zone between the solidified front and the region of pulling where the temperature is between 1850 and 1900 deg. C is maintained not in excess of 30 deg. C/cm. The tube so grown is annealed at a temperature between 1950 and 2000 deg. C by increasing the temperature at a rate of 30 to 40 deg. C/min and keeping the tube at said temperature during a period between 3 and 4 hours. After that the tube is cooled down to room temperature at a rate of 30-40 deg. C/min.Disclosed is also an apparatus which enables said temperature gradient to be maintained while pulling the tube.