FIELD: chemistry.
SUBSTANCE: invention pertains to growing halogen monocrystals from liquid melt, specifically sodium iodide or caesium iodide, in a temperature gradient and using a heating element, dipped in the liquid melt. The method involves growing monocrystals by drawing down crystals from liquid melt in a crucible at a temperature gradient with use of a growth chamber and a furnace with multi-section background heating. The crystals are grown in saturated vapours of components of the grown crystal with use of an extra heater (OTF heater), dipped in the liquid melt near the crystallisation front thermocouple in the case of the OTF heater and at the bottom of the crucible, mounted on a support. In the growing process at the crystallisation front, a longitudinal temperature gradient is formed ranging from 50 to 200°C/cm as well as a radial temperature gradient ranging from 2 to 8°C/cm. After growing the monocrystal is cooled under conditions of the longitudinal and radial temperature gradients less than 0.2°C/cm. The method is implemented in a device consisting of a growth chamber 8, furnace with a multi-section background heater 11, different in that, it has an extra OTF heater 4, dipped in liquid melt 5 near the crystallisation front, thermocouples 17 and 18, inside the quartz case 20 of the OTF heater and support 3, respectively inoculating crystal 1a in form of a disc, embedded in a quartz crucible 2 without a bottom. The OTF heater is mounted by the wall of the crucible 2 without a gap, and in its case 20, there are 4 to 8 openings or grooves at the lateral surface with a cross section of not more than 0.7-1 mm2 for inlet of fresh liquid metal from the region over the OTF heater to the growth region. In that case when the liquid metal flows between the innoculant and the walls of the crucible, it hardens and so does not flow from it. Absence of direct contact between the innoculant and the crucible prevents the rise of stress at the initial crystallisation stage and there are no possible defects during growth.
EFFECT: invention allows for sealing the composite crucible, obtain quality monocrystals-scintillators, avoiding an extra burning stage after extraction from the chamber.
23 cl, 3 ex, 2 dwg
