The charge for the cultivation of yttrium-aluminum garnet
(57) Abstract:The charge for the cultivation of yttrium-aluminum garnet from the melt, including the oxides of yttrium, aluminum, ytterbium, and one of group IV elements (zirconium, hafnium, silicon), characterized in that it further comprises the oxides of rare earth elements from lanthanum to terbium) or their mixture in the following ratio, wt.%:
Yttrium oxide - 20,71 - 56,47
The ytterbium oxide is 0.5 - 30,0
Dioxide element of group IV - 0,02 - 0,2
The oxide of rare earth element or a mixture of 0.005 - 15
Alumina - Rest
FIELD: triple chalcogenide monocrystals designed for using in quantum electronics and optronics.
SUBSTANCE: monocrystal has chemical formula LiGaTe2, three-dimensional tetragonal-symmetry group I42d, lattice parameters a = 6.338Å, c = 11,704Å, volume of elemental cell V = 470.1Å, coordination number Z = 16, density 4.689 g/cm3 and it is grown by Bridgeman-Stockbarger process at preliminary synthesis of compound of elemental components Li, Ga, Te. Monocrystal is suitable for converting laser infrared irradiation from wavelength no less than 520 nm up to wavelength 20 micrometers.
EFFECT: new lithium containing chalcoghenide monocrystals suitable for using in optics of mean range of IR-irradiation.
3 cl, 2 dwg
FIELD: processes for high-temperature crystallization from melts, possibly growing of super-large mono-crystals of refractory oxides.
SUBSTANCE: method for growing refractory oxide mono-crystals by directional horizontal crystallization comprises steps of creating in vacuum chamber by means of heating devices temperature field; melting in created field initial crystallized material placed in container being open upwards reservoir in the form narrowed at one side parallelepiped shaped boat; forming crystal from oriented mono-crystalline seed arranged in narrowed part of container and made of material corresponding to grown crystal due to moving container with melt charge in gradient temperature field. At growing process, crystallization speed is controlled in axial, radial and vertical directions by regulating relations of heat flux values of heating devices irradiation, namely heat flux of radiant energy incident to melt heel surface and conductive heat flux passing through lateral walls and bottom of container. Desired temperature gradients of temperature field along interface of melt material phases and grown crystal - crystallization front are provided due to setting difference between temperature of phase interface and equilibrium melting temperature equal to 15 - 25°C. Inclination angle of crystallization front relative to plane of container bottom at forming vertical temperature gradient is set in range 55 -90°. Width of seed is selected in range 3 - 5 mm; enlargement angle of mono-crystal is set in range 100 - 140°; values of enlargement arms of mono-crystal are selected up to 300 mm. Invention provides increased useful surface area (rectangular portion) of grown crystals by 30 - 45% and flat crystallization front in zones of lateral corrugations of container.
EFFECT: minimized possibility of occurring stresses, complete elimination of block formation in grown crystal.
5 cl, 1 tbl, 2 dwg
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
SUBSTANCE: method of manufacturing cadmium telluride monocrystal lies in loading polycrystal half-product into crucible, hermetization with further crucible vacuuming, melting of half-product, cooling of obtained ingot, its standing at certain temperature and further cooling to room temperature; polycrystal half-product is loaded into crucible together with pure cadmium sample, whose weight is determined by Clapeyron-Mendeleev equation, crucible is exhausted to pressure 10-6-10-7 mm of mercury, half-product is melted, ensuring temperature gradient on height 1-5°C/cm, half-product melt is stood at melting temperature during 2-4 hours, then half-product is cooled at rate 0.5-1,0°C/hour to full crystallization; obtained crystal is cooled at rate 40-60°C/hour to temperature 920-960°C, crystal is stood at said temperature during 8-12 hours, then it is cooled again at rate 40-60°C/hour to temperature 820-860°C and stood at during 8-12 hours, then crystal is cooled to temperature 700-720°C and stood during 8-12 hours, after which crystal is cooled at rate 10-20°C/hour to room temperature and removed from crucible as end-product.
EFFECT: high perfection of microstructure and high optical characteristics.
1 ex, 2 dwg
FIELD: metallurgy, crystal growing.
SUBSTANCE: invention refers to growing mono-crystals out of melt in temperature gradient with implementation of device for melt and crystal transfer. The method includes heating of a crucible with a seed, melting charge and upper portion of the seed, and succeeded crystallisation by means of cooling in temperature gradient. Crystallisation is carried out with a heater in a pressure tight case "ОТФ"- heater immersed into melt and with a lattice with through apertures; the said lattice is assembled inside a sleeve installed in the crucible without a gap against its interior walls; also the sleeve is primarily arranged between the upper portion of the seed and "ОТФ"- heater, and further by means of the heater the sleeve is lowered till the lattice takes place of melted upper portion of the seed and till melt completely fills through apertures of the lattice along its whole height. The method is carried out in the device containing the crucible with melt and the seed arranged in its lower portion; the said device additionally contains "ОТФ"- heater in the pressure tight case immersed into melt and lattice with through apertures arranged inside the sleeve with horizontal grooves in its upper portion; also the sleeve is installed between the upper portion of the seed and "ОТФ"- heater without the gap between its side surface and interior surface of the crucible; "ОТФ"- heater is designed to travel down inside the crucible; while the crucible is placed on the bottom-support. Mono-crystals, while being crystallised from the seed crystal, grow inside cells with dimensions from 5 to 500 mcm. Thus the lattice for matrix detector is obtained, all cells of which are filled with mono-crystal material.
EFFECT: producing lattice for matrix detector all cells of which are filled with mono-crystal material.
3 cl, 3 ex, 1 dwg