Abstract: A cylindrical alkali halide melt-grown single-crystal-type ingot is axially compressed in a heated dual-platen press while in a plastic state. The ingot is located mid-way between two parallel, planar, vertically extending barriers. By properly orienting the platens and the barriers with respect to the crystal lattice structure of the ingot, the ingot can be forged into a rectangular block that is not only devoid of peripheral cracks and fissures but that also has more uniform properties even when impurities and activator (Tl, in the case of NaI(Tl)) are not uniformly distributed within the initial single-crystal ingot.

Abstract: A cylindrical alkali halide single-crystal-type ingot having an axis generally coinciding with the ?001! crystallographic direction is compressed in a heated dual platen press. To produce an approximately rectangular compressed ingot that is devoid of cracks and fissures at and adjacent the periphery, the surface of the ingot is flatted. For crystals having a face-centered lattice (e.g. NaI), the flat is parallel to the (100) crystallographic plane. For crystals having a body-centered lattice (e.g. CsI), the flat is parallel to the (110) crystallographic plane. The flat is placed on the lower platen of the press to properly orient the crystallographic structure of the ingot with respect to the direction of compression.

Abstract: Single crystals are grown from a melt in a frame-mounted furnace housing consisting of a stationary top furnace member and a movable base furnace member adapted to be butt-joined to the top one, and a vertically reciprocatable crystal-pull rod with a seed crystal holder extending into the top furnace member. A crucible with a heater is arranged in the base member. The base member is movable from beneath the top furnace member to permit the pull rod and the grown crystal to be lowered for removal of the crystal without lateral movement of the pull rod and/or crystal frame. A heat insulated discharge vessel is provided for receiving and transporting the removed crystal.

Abstract: The invention relates to growing single crystals from melt. The disclosed apparatus includes a sealed chamber accommodating a crucible with the melt, the crucible being operatively connected with a drive effecting its rotation, a heater with thermal insulation means enclosing the crucible and a rod arranged coaxially with the crucible and carrying a seed holder, the rod being operatively connected with its own drive effecting its rotation and vertical displacement. In accordance with the invention, the operative connection between the crucible and its drive includes a support ring accommodated in the chamber and supporting thereon the crucible for their joint rotation during the crystal-pulling operation.

Abstract: The apparatus may be used for growing large-sized single crystals, such as optical and scintillation alkali halide single crystals, as well as semiconductor single crystals, from melt.The apparatus comprises means for pulling a single crystal from melt and a crucible made of two containers mounted coaxially in each other to define an annular space therebetween to which a charge is fed. The inner container protrudes downwards relative to the outer container, and melt is contained in the protruding portion thereof.Apertures are provided in the side wall of the inner container at the level of the bottom wall of the outer container for overflow of melt from the annular space to the inner container. Independent heaters are provided under the inner and outer container, respectively.

Abstract: An apparatus is designed for pulling oriented large-size single crystals from melt.The apparatus comprises a hollow rod having a seed crystal holder. The rod drive comprises a drive shaft mounted in the rod coaxially therewith, the rod and the drive shaft being in engagement for combined rotation and for reciprocations of the rod together with a carriage axially along the drive shaft.