Method of annealing crystals of group iia metal fluorides |
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IPC classes for russian patent Method of annealing crystals of group iia metal fluorides (RU 2421552):
 Method of thermal treatment of single-crystal substrate znte and single-crystal substrate znte / 2411311
Method includes the first stage of increasing temperature of single-crystal substrate ZnTe up to the first temperature of thermal treatment T1 and maintenance of substrate temperature within specified time; and the second stage of gradual reduction of substrate temperature from the first temperature of thermal treatment T1 down to the second temperature of thermal treatment T2, lower than T1 with specified speed, in which T1 is established in the range of 700°C≤T1≤1250°C, T2 - in the range of T2≤T1-50, and the first and second stages are carried out in atmosphere of Zn, at the pressure of at least 1 kPa or more, at least 20 cycles or at least 108 hours.
 Method of growing heat resistant monocrystals / 2404298
Crystals are grown using the Kyropoulos method with an optimum annealing mode, carried out while lowering temperature of the grown monocrystal to 1200°C at a rate of 10-15°C/hour and then cooling to room temperature at a rate of 60°C/hour.
Method of producing monocrystals of calcium and barium flourides / 2400573
Method involves crystallisation from molten mass through Stockbarger method and subsequently annealing the crystals through continuous movement of the crucible with molten mass from the upper crystallisation zone to the lower annealing zone while independently controlling temperature of both zones which are separated by a diaphragm. The crucible containing molten mass moves from the crystallisation zone to the annealing zone at 0.5-5 mm/h. Temperature difference between the zones is increased by changing temperature in the annealing zone proportional to the time in which the crucible moves from the beginning of crystallisation to its end, for which, while maintaining temperature in the upper crystallisation zone preferably at 1450-1550°C, in the lower annealing zone at the beginning of the crystallisation process temperature is kept at 1100-1300°C for 30-70 hours, thereby ensuring temperature difference of 450°C between the zones at the beginning. Temperature of the annealing zone is then lowered to 500-600°C in proportion to the speed of the crucible with the growing crystal. Temperature of the annealing zone is then raised again to 1100-1300°C at a rate of 20-50°C/h, kept for 18-30 hours after which the zone is cooled to 950-900°C at a rate of 2-4°C/h, and then at a rate of 5-8°C/h to 300°C. Cooling to room temperature is done inertially. Output of suitable monocrystals of calcium and barium fluorides with orientation on axes <111> and <001>, having high quality of transparency, uniformity, refraction index and double refraction is not less than 50%.
 Superstrong single crystals of cvd-diamond and their three-dimensional growth / 2389833
Method includes placement of crystalline diamond nucleus in heat-absorbing holder made of substance having high melt temperature and high heat conductivity, in order to minimise temperature gradients in direction from edge to edge of diamond growth surface, control of diamond growth surface temperature so that temperature of growing diamond crystals is in the range of approximately 1050-1200°C, growing of diamond single crystal with the help of chemical deposition induced by microwave plasma from gas phase onto surface of diamond growth in deposition chamber, in which atmosphere is characterised by ratio of nitrogen to methane of approximately 4% N2/CH4 and annealing of diamond single crystal so that annealed single crystal of diamond has strength of at least 30 MPa m1/2.
 Ceramic laser microstructured material with twinned nanostructure and method of making it / 2358045
Proposed laser material is a ceramic polycrystalline microstructure substance with particle size of 3-100 mcm, containing a twinned nanostructure inside the particles with size of 50-300 nm, made from halides of alkali, alkali-earth and rare-earth metals or their solid solutions, with vacancy or impurity laser-active centres with concentration of 1015-1021 cm-3. The method involves thermomechanical processing a monocrystal, made from halides of metals, and cooling. Thermomechanical processing is done until attaining 55-90% degree of deformation of the monocrystal at flow temperature of the chosen monocrystal, obtaining a ceramic polycrystalline microstructure substance, characterised by particle size of 3-100 mcm and containing a twinned nanostructure inside the particles with size of 50-300 nm.
Method for thermal processing of semi-finished abrasive tools on organic thermosetting binding agents / 2351696
Invention is related to the field of abrasive processing and may be used in production of abrasive tools for polishing of blanks from different metals and alloys. Full cycle of thermal processing of semi-finished abrasive tools on organic thermosetting binding agents includes stages of preliminary heating and hardening in microwave field of SHF- chamber with frequency of 2450 MHz for abrasive tool with thickness of up to 100 mm and with frequency of 890 - 915 MHz for abrasive tool with thickness of more than 100 mm. Prior to SHF-thermal processing semi-finished abrasive tools are placed into radio transparent steam-and-gas permeable container-thermostat. After temperature of thermosetting binding agent complete polymerization has been achieved, and after pause at this temperature, thermostat is withdrawn from SHF-chamber, and semi-finished abrasive tools are kept in thermostat until their temperature drops at least by 80°C. After that thermostat is opened, semi-finished products are cooled in open air and then withdrawn from thermostat.
Method for thermal treatment of half-finished abrasive tools on organic thermosetting binders / 2349688
Group of half-finished abrasive tools prior to thermal treatment is placed into thermally insulated steam and gas permeable radiolucent thermostat. Full cycle of mentioned half-finished articles thermal treatment is carried out. Cycle includes stages of preliminary heating and hardening of half-finished items group in microwave field of SHF-chamber with frequency of 2,450 MHz for abrasive tools with thickness of up to 100 mm and frequency of 890...915 MHz for abrasive tools with thickness of more than 100 mm to achieve temperature of organic thermosetting binder complete polymerisation with further maintenance at this temperature. In process of SHF thermal treatment volatile substances are forcedly and uniformly removed from free volume of thermostat through slots arranged in front and back walls of thermostat. Possibility for vapours of volatile substances to be saturated is eliminated with preservation of maximum possible effect of thermostat working area thermal insulation effect and provision of half-finished items temperature difference that does not exceed ±10% of its average level inside thermostat.
 Method of obtaining synthetic minerals / 2346887
Invention concerns obtaining synthetic minerals and can be applied in technics and jewellery. Method of artificial mineral synthesis is implemented by crucible method involving blend processing in plasma torch of plasmotron to obtain melt, melt drop feeding into crucible by plasma-forming gas flow with further crystallisation. Seeding agent is placed at crucible bottom in advance, and synthesis is performed at plasmotron output of 12 kW and blend feed rate of 2-3 g/min with simultaneous annealing of the melt crystallised on seeding agent in annular furnace for 2-3 hours at 1000°C. Preliminary placement of seeding agent to crucible bottom ensures accelerated crystal growth and higher process performance. Simultaneous annealing of artificial minerals reduces tension in end product significantly.
 Method of producing mono-crystalline plates of arsenide-indium / 2344211
Invention refers to semi-conductor technology of AIIIBV type compositions. The method is implemented by means of bombarding mono-crystalline plates of arsenide-indium with fast neutrons with following heating, annealing and cooling. The mono-crystalline plates are subject to bombardment with various degree of compensation at density of flow not more, than 1012 cm-2 c-1 till fluence F=(0.5÷5.0)·1015 cm-2 , while annealing is carried out at 850÷900°C during 20 minutes at the rate of heating and cooling 10 deg/min and 5 deg/min correspondingly.
Method of hardening dislocation-free silicon plates / 2344210
Invention refers to process of production of dislocation free plates of semi-conducting silicon cut out of mono-crystals, grown by Czochralski method, and applied for producing integrated circuits and discrete electronic devices. Method of upgrading mechanical hardness of mono-crystalline dislocation-free silicon plates with oxygen contents at the level 6×1017-9×1017 cm-3 is performed by two-stages thermal treatment in inert medium, for instance, in argon, initially at the temperature of 1000÷1020°C during 10-15 minutes, and further at the temperature of 600-650°C during 7.5-8.5 hours with following cooling in the air.
Method of producing monocrystals of calcium and barium flourides / 2400573
Method involves crystallisation from molten mass through Stockbarger method and subsequently annealing the crystals through continuous movement of the crucible with molten mass from the upper crystallisation zone to the lower annealing zone while independently controlling temperature of both zones which are separated by a diaphragm. The crucible containing molten mass moves from the crystallisation zone to the annealing zone at 0.5-5 mm/h. Temperature difference between the zones is increased by changing temperature in the annealing zone proportional to the time in which the crucible moves from the beginning of crystallisation to its end, for which, while maintaining temperature in the upper crystallisation zone preferably at 1450-1550°C, in the lower annealing zone at the beginning of the crystallisation process temperature is kept at 1100-1300°C for 30-70 hours, thereby ensuring temperature difference of 450°C between the zones at the beginning. Temperature of the annealing zone is then lowered to 500-600°C in proportion to the speed of the crucible with the growing crystal. Temperature of the annealing zone is then raised again to 1100-1300°C at a rate of 20-50°C/h, kept for 18-30 hours after which the zone is cooled to 950-900°C at a rate of 2-4°C/h, and then at a rate of 5-8°C/h to 300°C. Cooling to room temperature is done inertially. Output of suitable monocrystals of calcium and barium fluorides with orientation on axes <111> and <001>, having high quality of transparency, uniformity, refraction index and double refraction is not less than 50%.
 Pr-containing scintillation monocrystal, method of making said crystal, radiation detector and inspection device / 2389835
Oxide scintillation monocrystals are designed for devices for X-ray computed tomography inspection through illumination with radiation. A Pr-containing monocrystal based on fluorides, specifically a Pr-containing oxide monocrystal of the garnet type, a Pr-containing oxide monocrystal of the perovskite type and a Pr-containing monocrystal of the silicate oxide type, as well as a Pr-containing rare-earth metal oxide monocrystal are proposed.
 Laser material / 2369670
Invention relates to electronic engineering material and can be used in making new devices in photonics, quantum electronics and ultraviolet optics. The laser material, based on barium and yttrium fluoride crystal, activated by trivalent ions of cerium BaY2F8:Ce3+, additionally contains ytterbium and lutetium ions in concentration of 0.5-5.0 at % and 1-5 at %, respectively.
 Method of receiving of optical material for quantum electronics on basis of crystals of double fluorides / 2367731
Invention relates to crystal growth process and can be used at creation of activated crystalline materials with predicted properties for needs of photonics, quantum electronics and optics. Optical material on the basis of crystals of double fluorides of scheelite structure is received by means of crystal growth from melt of ingredients LiF, YF3, LuF3, LnF3, where Ln - trivalent ions of cerium subgroup of lanthanide row, herewith into charge for preparation of melt it is introduced lutetia fluoride in amount from 50 mole % up to 90 mole % relative to yttrium fluoride.
 Method of preparing raw material from sodium or caesium iodides for growing crystals / 2363777
Invention relates to the technology of preparing free running salts of metal halides and can be used in chemical industry, particularly for preparing initial salts of sodium or caesium iodides for growing monocrystals - Nal(Tl), Csl, CsI(Tl), CsI(Na). The method involves loading initial salt into an ampoule, evacuation of the ampoule, heating the salt to 420-450°C with constant evacuation, letting in dry air with subsequent holding, repeated air inlet, holding and pumping in the given modes and repeated evacuation, after which carbon dioxide gas is let in until attaining pressure of 200-400 mm Hg and keeping the salt in a carbon dioxide gas atmosphere for 15-20 minutes.
 Laser material / 2362844
Invention relates to materials for electric engineering; it can be used for creation of new devices in the area of photonics, quantum electronics and UF-band optics. Based on crystals of lithium and lutetium fluorides activated by trivalent cerium ions laser material contains additionally yttrium and ytterbium fluorides in compliance with chemical formula LiLu1-xYxYbyF4:Ce, where x=0.5÷0.8, y=0-0.05.
Ceramic laser microstructured material with twinned nanostructure and method of making it / 2358045
Proposed laser material is a ceramic polycrystalline microstructure substance with particle size of 3-100 mcm, containing a twinned nanostructure inside the particles with size of 50-300 nm, made from halides of alkali, alkali-earth and rare-earth metals or their solid solutions, with vacancy or impurity laser-active centres with concentration of 1015-1021 cm-3. The method involves thermomechanical processing a monocrystal, made from halides of metals, and cooling. Thermomechanical processing is done until attaining 55-90% degree of deformation of the monocrystal at flow temperature of the chosen monocrystal, obtaining a ceramic polycrystalline microstructure substance, characterised by particle size of 3-100 mcm and containing a twinned nanostructure inside the particles with size of 50-300 nm.
 Infrared potassium and rubidium pentobromplumbite crystal laser array / 2354762
There is disclosed infrared potassium and rubidium pentobromplumbite crystal laser array as described by formula KXRb1-XPb2Br5 where x changes within 0.2≤x≤0.5.
Method of cleaning iodides of alkali metals from impurities of organic compounds / 2341458
Salt to be purified is put into an ampoule. The ampoule is evacuated and the salt is heated with constant evacuation. Heating is done gradually at a rate of 20-50°C per hour to 420±20°C. Pressure is kept constant at 10-3 mm Hg. The invention allows for purifying iodides of alkali metals to concentration of impurities of organic compounds less than 10-3 wt % of carbon.
 Method of growing monocrystals-scintillators based on sodium iodide or caesium iodide and device for implementing method / 2338815
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.
Method of production of the defected crystals based on the metal halides solid solutions / 2287620
The invention is pertaining to the field of the synthesis of the real crystals, i.e. the crystals with defects and based on the metals halides solid solutions. The method may be applied in production of the homogeneous multicomponent charge for the crystals growing from the melt, the gas phase, the water solutions, as well as at hydrothermal conditions. The substance of the invention consists that the multicomponent charge is prepared in the form of the single-phase solid solutions by non-mechanical mixing, at which it is impossible to gain one homogeneous phase of the solid solution even at repeated remelting, but only by the synthesis from the water solutions of the hydrochloric acid with usage of the certain modes. For this purpose they take the individual halides of the following metals - TlCl, TlBr, TlI, AgCl, AgBr, AgI in the quantities corresponding to their contents in the solid solution - AgClxBrl-x, AgClxBryIl-x-y, KRS-5, KRS-6 and dissolve in 5-6 M (mol/l) hydrochloric acid at the temperature of 95-100°C. After saturation the solutions are cooled to 50-60°C with the cooling speed of 4-5°C per hour, iterating the pointed cycle from three up to five times. The crystals of the solid solutions on the basis of the halides of the metals, i.e. the crystals with defects in comparison with the crystals on the basis of the individual halides of the metals possess the heightened optical-mechanical properties: the expanded range of the transparency, the increased mechanical strength, the heightened radiation and ray stability. The pointed properties additionally may be improved, can be refined and, besides, it is possible to give the crystals new properties, for example, the scintillation properties, introducing thallium halides into the solid solutions ofAgClxBryIl-x-y andAgClxBr1-x.
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FIELD: physics. SUBSTANCE: method involves subjecting a grown and hardened, i.e. correctly annealed crystal, to secondary annealing which is performed by putting the crystal into a graphite mould, the inner volume of which is larger than the crystal on diameter and height, and the space formed between the inner surface of the graphite mould and the surface of the crystal is filled with prepared crumbs of the same material as the crystal. The graphite mould is put into an annealing apparatus which is evacuated to pressure not higher than 5·10-6 mm Hg and CF4 gas is then fed into its working space until achieving pressure of 600-780 mm Hg. The annealing apparatus is then heated in phases while regulating temperature rise in the range from room temperature to 600°C, preferably at a rate of 10-20°C/h, from 600 to 900°C preferably at a rate of 5-15°C/h, in the range from 900 to 1200°C preferably at a rate of 15-30°C/h, and then raised at a rate of 30-40°C/h to maximum annealing temperature depending on the specific type of the metal fluoride crystal which is kept 50-300°C lower than the melting point of the material when growing a specific crystal, after which the crystal is kept for 15-30 hours while slowly cooling to 100°C via step-by-step regulation of temperature decrease, followed by inertial cooling to room temperature. EFFECT: high quality of producing monocrystals of metal fluorides owing to increase in their homogeneity with maximum reduction of defects in grown crystals, which ensures high yield of the material with good optical characteristics, use of a special mode of preparation and carrying out secondary annealing primary grown and hardened crystals of metal fluorides enable to eliminate microinhomogeneities and small-angle off-orientations of crystals. 1 ex
The invention relates to the manufacture of optical single crystals of metal fluorides, in particular to the way their secondary annealing. The optical single crystals of fluorides of alkaline earth metals produced by their growth from the melt using known techniques, such as Czochralski, Bridgman stockburger and other Widely spread are optical single crystals in the form of fluorides of calcium, magnesium and barium, which are used in modern instrumentation. For the manufacture of optical elements is often required optical material with extremely high requirements to the optical characteristics of vacuum ultraviolet (VUV) spectral region. These materials meet the strict requirements for optical homogeneity, birefringence, crystal orientation and resistance under the influence of excimer laser. Industrial cultivation of optical single crystals by Bridgman-stockburger, based on the movement of the crucible with the melt kristallicheskogo substances through the temperature field with the specified gradients in high vacuum. The experimental data obtained by growing crystals of fluorides of metals, show a special difficulty of manufacturing technology quality Cristallo is fluoride, optical quality which depend from almost every condition modes at all stages of growing and annealing. Grown and annealed in carefully selected conditions, the crystal may contain in its volume microheterogeneity and the small-angle misorientation, which affects its optical homogeneity. The prior art methods of producing single crystals from the melt. In the application of the Russian Federation No. 2001111056 16.04.2001 published 10.04.2003 index IPC SW 11/00, 11/14 and SW 29/12, described is a method of growing single crystals of calcium fluoride, in which the crystallization from the melt and annealing of the crystals by moving the crucible from the crystallization zone to zone annealing at independent regulatory regimes of the two regions between which maintain the temperature of 250-450°C With gradient 8-12°C/see the crucible is Moved from the upper zone and the crystallization zone annealing carried out at a rate of 1-3 mm/h, kept in a zone of the first annealing for 20 to 40 hours at a temperature of 1100-1300°C, then cooled with a speed of 2-4°C/h to 950-900°C, and then with a speed of 5-8°C./hour to 300°C, after which produce inertial cooling. In the crystallization zone temperature is maintained at 1500±50°C, and in the zone annealing in the upper part of the support temperature of 1100-1300°C. In this way it is claimed technical result consists in extracting the AI single crystals of calcium fluoride high optical homogeneity Δn=1·10 -6and with a small birefringence δ=1-3 nm/cm for crystals of cylindrical shape with a diameter of 300 mm and a height of 65 mm However, the crystals obtained in the described manner, do not meet today for all parameters, neobhodimim in the manufacture of optical parts of the crystals of fluorides, and it requires an even higher quality - uniformity, reduction of possible defects, which occur mostly in the annealing process. Microheterogeneity and low-angle misorientation of the crystal appear due to the radial temperature gradient in the crystallization process at all stages. As a result, the yield using this method is small and amounts to a maximum of 25%. In US patent No. 7014703 published 30.06.2005 index IPC SW 29/12, 33/12 described method of annealing of crystals of fluorides of group IIA metals, which consists in cleaning and polishing grown and annealed crystal to eliminate surface defects and subsequent secondary annealing in order to release residual stresses. Crystal for the secondary annealing placed in an oven in the holder, heated to a temperature of 50-150°C. below the melting point and cooled by the program, for example, with a constant rate of 1-10°C./hour to room temperature or in stages: from the top temperature to the temperature of 250-500°C. below the melting point / min net with the calling of 1-10°C./hour, to 500-750°C below the melting point with the speed of 5-20°C./hour and then to a temperature in the range of 750-1000°C with a speed of 10-40°C./hour, then cooled to room temperature with a speed of 20-50°C/hour. In this way applied secondary annealing, which helps to improve the quality of the crystal to reduce residual stresses and the improvement of optical homogeneity. However, not solved completely the problem of elimination of microinhomogeneities and improve optical uniformity. The method according to US patent No. 7014703 taken as a prototype of the proposed method. The objective of the new approach is to improve the quality of manufacturing single crystals of fluorides of metals by increasing their uniformity with a maximum reduction of defects in the grown crystal, which will ensure the yield of material with high optical characteristics. The technical result is achieved due to the use of a special mode of preparation and holding of the secondary annealing is primary grown and hardened crystals metal fluoride, which helps to eliminate microinhomogeneities and low-angle misorientation of the crystals. The problem is solved in the method of annealing of crystals of fluorides of metals of groups IIA, namely, that grown and hardened, i.e. initially annealed crystal is subjected to the secondary of the jig, where unlike the prototype secondary annealing is conducted by placing the crystal in graphite form, the internal volume of which exceeds the size of the crystal diameter and height, and formed in the space between the inner surface of the graphite shape and surface of the crystal fall asleep pre-prepared powder of material of the same crystal, graphite form is placed in the installation annealing, which vacuum up to a pressure of not more than 5·10-6mm Hg, introducing her workspace gas CF4before the formation pressure in 600-780 mm Hg, then the installation for annealing heat gradually, adjusting the temperature rise in the range from room temperature up to 600°C, preferably with a speed of 10-20°C/hour, from 600 to 900°C, preferably with a speed of 5-15°C./hour, in the range from 900 to 1200°C, preferably with a speed of 15-30°C/hour, and then with a speed of 30-40°C/hour adjusted to the maximum annealing temperature depending on the specific type of crystal of fluoride of a metal which is selected at 50-300°C below the melting temperature of the material for the cultivation of a particular crystal, followed by an excerpt from 15 to 30 hours, and slow cooling to 100°C, which produce a gradual regulation of the temperature reduction, and then the inertial cooled to room temperature. The location of the crystal in graphite fo the mu Peresypkin space between the inner walls of the mold and the surface of the crystal crushed particles of the same material, as the crystal itself, provides uniform heat removal from the chip in the annealing process, and reducing the radial gradient. Vacuum installation for annealing to a pressure of 5·10-6mm Hg and run it gas CF4with the formation of normal pressure provides the annealing of the crystals in a fluorinating atmosphere that contributes to the stabilization of the stoichiometric composition of the crystal. The maximum temperature annealing must be below the melting temperature of the processed crystal at 50-300°C, to, first, do not heat the chip up to its melting, and secondly, to ensure the ductility of the material. The melting point for calcium fluoride is 1418°C for fluoride magnesium - 1255°C. for barium fluoride - 1354°C. the Optimum maximum temperature for secondary annealing for crystals of calcium fluoride is 1320±50°C for barium fluoride - 1250±20°C for fluoride magnesium - 1150±20°C. Gradual heating of the crystal with a specific selection of the speed of temperature increase due to the need to prevent thermal shock, which could lead to cracking of the crystal, which is tested empirically. Shutter speed for 15-30 hours at maximum temperature provides the balance of the heated mass of the crystal. Cooling to 100°C has going on the forth slowly with a specific selection of cooling rate on certain temperature ranges. The preferred mode of cooling from the top to 1000-950°C is the speed of 2.5-5°C/hour, from 950 to 700°C - cooling with a speed of 1.5 To 2.5°C/hour, from 200 to 100°C - cooling speeds of 10°C/hour. Proven experienced by the cooling mode of the crystal provides the best result for the solution of the task. The proposed mode of the secondary annealing allows to obtain crystals with the best performance optical homogeneity in the absence of microinhomogeneities and sans razorianfly, transmittance in the VUV region of the spectrum with no sviluppatori defects and low birefringence. A specific example of the method for annealing. For a detailed description of a specific example uses the material of barium fluoride in the form of a disk sizes up to 300 mm was grown using the Bridgman method-stockburger. In this case, it is appropriate to describe the process of growing the single crystal, which consists in the preparation of the source material, representing grains in the form of purified raw materials BaF2that mixed with 0.5-1% fluorinating agent PbF2and placed in a graphite crucible, which in turn is placed in a vacuum oven. Oven vacuum to a pressure of not more than 1·10-5mm Hg Vacuum furnace is a system of two heating zones top of which serves to melt the material, and the lower annealing. After evacuating the furnace is heated first to 500°C at the rate of 50-100°C./hour and maintained at this temperature for 5 to 10 hours for drying raw materials BaF2and next, the temperature in the upper zone to raise the melting temperature of the source material 1354°C at the rate of 20-50°C./hour, and in the lower zone to raise the temperature to the value at 150-800°C below the melting temperature. After melting the raw materials BaF2and the reaction of absorption PbF2impurities containing oxygen, the crucible of the upper zone of the melt slowly move to the lower area of annealing a speed of 1-5 mm/hour. During this move, crystallization occurs, which lasts up to 250 hours when the volume of the substrate 100 kg. When stopping crucible in the lower part of the vacuum furnace, the temperature of both zones reduce to room inertia that leads to hardening of crystals, reduce the formation of microinhomogeneities and low-angle misorientation. Cooled to room temperature, the crystal BaF2removed from the growth installation. Crystals BaF2are the most important optical material and their quality depends on the defectiveness of the real structure. It is known that in crystals BaF2grown in an industrial environment, there are microheterogeneity. Data microheterogeneity have the form of plates with a length of 0.1 μm and thick is 2.0 to 100 nm, and volume inhomogeneities in the crystal is several tenths of a percent. Any kind of inhomogeneities in the crystal, regardless of their origin undesirable in practical use as an optical element. Typical dimensions of microinhomogeneities meet the wavelengths of the UV-range and affect the spectral transmittance of the crystal BaF2 To eliminate the defects of the grown crystal BaF2applied secondary annealing that uses another vacuum unit, which includes the possibility of the gas inlet CF4that creates a fluorinating atmosphere. So, the grown crystal BaF2placed in a graphite crucible with the formation of the free space in its internal volume to fill his pre-prepared grains of crystals BaF2. This action promotes uniform heat removal from the chip and reduce the radial gradient in the secondary process of annealing. The filled crucible is placed in a unit for secondary annealing, which vacuum up to a pressure of not more than 5·10-6mm Hg, thereby removing oxygen from the working volume of the installation. Then in this working volume sleuth gas of CF4 to education in its pressure 750-770 mm Hg Then the installation of heat: temperatures of 800°C with the velocity of the th 10°C/hour, then to a temperature of 1000°C at a rate of 20°C/hour, and then to a temperature of 1250°C at 30°C/hour. Make the shutter speed at a maximum temperature of 1250°C for 15-20 hours for the onset of equilibrium in a heated crystal. After completion of the process of aging start slow reduction of temperature by the following program: stage 1 - up to 1000°C at 5°C/h, 2-I stage - up to 800°C at 3°C/h, 3-I stage - up to 400°C at a rate of 4°C/h, 4-I stage - up to 100°C at a rate of 10°C/hour. Final cooling to room temperature is inertial, then the crystal is removed from the installation for further machining and production from it of optical parts. The cooling procedure can be varied. The described process is tested empirically, and also tried the other modes, similar to the example above. Similarly, the obtained crystals of fluorides of calcium and magnesium. Differences of the processes associated with the melting temperature of a particular material. This has resulted in crystals of fluoride metals with uniformity to 1·10-6, lack sviluppatori defects (slip bands), with a minimum angle misorientation, the birefringence 1-5 nm/cm and a high transmittance characteristics in the VUV region of the spectrum and most importantly with a low percentage of microinhomogeneities. These characteristics close to the characteristics of an ideal crystal. The proposed method secondary annealing of the crystals with the aim of elimination of defects by the presence of microinhomogeneities residues and impurities of oxygen can be used for crystals of strontium fluoride, and mixtures of fluorides of metals. Method of annealing of crystals of fluorides of metals of groups IIA, namely, that grown preliminarily annealed crystal is subjected to a secondary annealing, characterized in that the secondary annealing is conducted by placing the crystal in graphite form, the internal volume of which exceeds the size of the crystal diameter and height, and formed in the space between the inner surface of the graphite shape and surface of the crystal fall asleep pre-prepared powder of material of the same crystal, graphite form is placed in the installation for stand-alone annealing, which vacuum up to a pressure of not more than 5·10-6mm Hg, and then injected into her workspace gas CF4before the formation pressure in 600-780 mm Hg, then the installation for stand-alone annealing heat gradually, adjusting the temperature in the range from room temperature to 600°C., preferably with a speed of 10-20°C./h, in the range from 600 to 900°C, preferably with a speed of 5-15°C./h, in the range from 900 to 1200°C., preference is sustained fashion with the speed of 15-30°C/h, and then about 30 to 40°C/h adjusted to the maximum annealing temperature depending on the specific type of crystal of fluoride of a metal which is selected at 50-300°C below the melting temperature of the material for the cultivation of a particular crystal, followed by an excerpt from 15 to 30 h and slow cooling to 100°C, which produce a gradual regulation of the temperature reduction, and then the inertial cooled to room temperature.
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