|
Method of producing optically transparent garnet monocrystals Garnet monocrystals are obtained using a Czochralski method by melting a starting mixture, which includes a calcium-containing additive in the form of calcium oxide or carbonate, and growing a monocrystal from the melt on an oriented seed crystal with diameter of 2-8 mm with a crystal rotational speed of 2-10 rpm, followed by annealing in a hydrogen atmosphere at 850-950°C for about 5 hours until the orange colour disappears, wherein crystal pulling on the oriented seed crystal is carried out at a rate of 0.5-2 mm/h, and the starting mixture used is a mixture of terbium, scandium and aluminium oxides, with the following ratio of components, wt %: terbium oxide - 65.85-66.98, aluminium oxide - 17.96-23.14, scandium oxide - 9.88-16.19. After growing, the crystal is annealed in a hydrogen atmosphere at 850-950°C for about 5 hours until the orange colour disappears. The obtained monocrystals are used to make magnetooptic elements with a diameter of more than 30 mm with an absorption coefficient of 0.8·10-3 cm-1, Verdet constant of 46-48 rad/(m·T) at wavelength of 1064 nm, medium breakdown threshold of not less than 5 J/cm2 at 10 Hz at wavelength of 1064 nm. |
|
|
Production of single-crystal white diamond Invention relates to production of diamonds for jewelry. This process comprises placing the substrate with diamond grain of preset size and preset optical orientation into chemical vapour-phase deposition (CVD). Then, hydrogen, hydrocarbon gas containing carbon, nitrogen and gas including diborane are fed into the chamber. Both are adapted for acceleration of diamond growth on said substrate. Electric field is applied to form plasma nearby said substrate to cause stepwise diamond growth thereat. CVD process is terminated in the chamber, faceting is performed and undesirable diamond is removed from grown diamond. Diamond is cleaned and facetted after annealing at preset temperature for preset time interval. Fining faceting of diamond is performed, it is finished and dyed. |
|
Method for growing gadolinium-scandium-aluminium garnet crystals for passive laser shutters Invention refers to crystal-growth technology for passive laser shutters used in state-of-the-art lasers and light radars operating in the range of 1.2-1.55 mcm. The crystals are grown by Czochralski method from the raw furnace charge melt, wherein the furnace charge is gadolinium-scandium-aluminium garnet Gd2.88Sc1.89Al3V0.03O12 produced by solid-phase synthesis; vanadium is introduced in the form of oxide V2O5; the crystal growing process is performed in the argon medium at a chamber pressure of 1.2-1.8 atm; the crystal is then annealed in vacuum 3-5·10-4 mmHg at a temperature of 1,600°C for 3-6 hours. |
|
|
Production of alloyed zinc chalcogenides and their solid solutions This method comprises application of doping element film on the surface of specimen of zinc chalcogenides or their solid solutions. Said doping element can be one or several elements of the following series: chromium, cobalt, iron. Then, diffusion annealing is performed at 90-200 MPa and 1100°C-1350°C. |
|
Invention relates to technology of producing coloured diamond materials, which can be applied as precious stones or cutting instruments. Method includes stages of growing monocrystalline diamond material in accordance with CVD-technology, with diamond material having concentration of single substituting nitrogen atoms [Ns 0] less than 1 ppm; initial CVD-diamond material is colourless, or, in case it is not colourless, then, according to colour gradation brown or yellow, and if it is brown according to colour gradation, then it has level G (brown) of colour gradation or better for diamond stone with 0.5 carat weight with round diamond cut, and if it is yellow according to colour gradation, it has level T (yellow) of colour gradation or better for diamond stone with 0.5 carat weight with round diamond cut, and irradiation of initial CVD-diamond by electrons to introduce isolated vacancies into diamond material in such a way that product of the total concentration of vacancies × way length [Vt]×L, in irradiated diamond material at said stage or after additional processing after irradiation, including annealing irradiated diamond material at temperature at least 300°C and not higher than 600°C, constitutes at least 0.072 ppm cm and not more than 0.36 ppm cm. |
|
Method of forming high-quality heterostructures of light-emitting diodes Invention can be used to produce high-quality semiconductor light-emitting diodes (LED) based on heterostructures of A3B5 compounds. The method includes irradiating a plate with heterostructures with integral electron flux with density of 1014-1017 el/cm2 and energy of 0.3-10 MeV at a temperature not higher than minus 70°C, followed by rapid thermal annealing at a temperature higher than 600°C with photon flux in the visible spectrum with radiation intensity of 1-10 W/cm and energy higher than the band-gap of the semiconductor layer of the heterojunction the narrowest band-gap. |
|
Method of processing monocrystalline cvd-diamond and obtained product Invention can be used in obtaining jewellery diamonds. method of introduction of NV-centres in monocrystalline CVD-diamond material includes the following stages: irradiation of CVD-diamond material, containing single substituting nitrogen, for introduction of isolated vacancies in concentration at least 0.05 ppm and at most 1 ppm; annealing irradiated diamond to form NV-centres from at least some of defects of single substituting nitrogen and introduced isolated vacancies. |
|
Invention relates to improved method of obtaining workpieces from silver halides and their solid solutions for fibrous infrared lightguides, which includes application on silver halide crystal-core of crystalline shell of crystalline silver halide with refraction index lower than in crystal-core, and thermal processing. Shell on crystal-core is applied by ion-exchange diffusion in ion-exchange source, as the latter taken is finely disperse silver halide powder with coarseness 1-20 mcm, diffusion is carried out at temperature, close to melting temperature of crystal-core in atmosphere of mixture of vapours of halides, included into composition of crystal material and powder, taken in equal ratio under pressure 0.2-0.5 atm. |
|
|
Method of obtaining a material for a high temperature mass-sensitive piezoresonance sensor based on a monocrystal of lanthanum-gallium aluminium tantalate, the composition of which corresponds to formula La3Ta0.5Ga5.5-xAlxO14, where x=0.1-0.3, characterised by the electric resistance not less than 109 Ohm at a temperature of 20-600°C, includes growing of monocrystals from a melt of oxides its component constituents in an atmosphere of an oxidiser-containing inert gas, and additional annealing in air at a temperature of 1050-1150°C for 41-43 hours. |
|
Method of forming high-quality mos structures with polysilicon gate Invention relates to microelectronics and can be used to produce high-quality, high-power double-diffused MOS transistor, CMOS integrated circuits and CCD devices. The method includes thermal annealing of MOS structures in the temperature range of 600-850°C in an electric field with field intensity of 10-100 V/cm, while simultaneously irradiating with light in the visible and near-infrared spectrum in the wavelength range λ=0.5-1.4 mcm with radiation intensity of 1-10 W/cm2 and with a polysilicon gate with thickness of not more 0.6 mcm on an oxide located on a silicon substrate. |
|
Method for making fancifully coloured orange monocrystalline cvd-diamond, and finished product Monocrystalline diamond material that has been grown using a CVD method and has concentration of single substituent nitrogen [Ns 0] of less than 5 ppm is irradiated to introduce isolated vacancies V to at least some part of the provided CVD-diamond material so that total concentration of isolated vacancies [VT] in the obtained diamond material is at least more than (a) 0.5 ppm and (b) by 50% more than concentration [Ns 0] in ppm in the provided diamond material; after that, annealing of the obtained diamond material is performed so that chains of vacancies can be formed from at least some of the introduced isolated vacancies at the temperature of at least 700°C and maximum 900°C during the period of at least 2 hours; with that, irradiation and annealing stages reduce the concentration of isolated vacancies in diamond material, due to which concentration of isolated vacancies in the irradiated and annealed diamond material is <0.3 ppm. |
|
Method for formation of bidomain structure in single-crystal plates Electrodes in the form of a system of parallel strings are applied onto two flat-parallel faces of the crystal, which are aligned at the angle of z+36° to the polar axis, wire platinum contracts are connected to electrodes, the assembled cell is placed into a furnace and heated to temperature of phase transition - Curie temperature under action of a heterogeneous electric field, as a result of which two oppositely charged domains of equal volume are formed with a flat domain-to-domain border. |
|
Method of making crystalline workpieces of solid solutions of silver halides for optical components Method involves loading starting separate silver chloride and silver bromide salts into a container made of heat-resistant glass, fusing said salts to a given composition of solid solution, growing a monocrystal in a halogenating atmosphere by moving the container in a temperature gradient, cooling the grown crystal to room temperature and removing the crystal from the container; the monocrystal is then heated at a rate of 50-60°C per hour to temperature of 250-270°C, held at said temperature for 1-2 hours, cooled at a rate of 20-25°C per hour to temperature of 100-150°C and then cooled at a rate of 30-40°C per hour to room temperature. |
|
|
Laser fluoride nanoceramic and method for production thereof Fluoride nanoceramic is obtained by thermomechanical treatment of the starting crystalline material made from CaF2-YbF3, at plastic deformation temperature to obtain a workpiece in form of a polycrystalline microstructured substance, which is characterised by crystal grain size of 3-100 mcm and a nanostructure inside the grains, by annealing on air at temperature of not less than 0.5 of the melting point with compaction of the obtained workpiece in a vacuum at pressure of 1-3 tf/cm2 until the end of the deformation process, followed by annealing in an active medium of carbon tetrafluoride at pressure of 800-1200 mmHg. The starting crystalline material used can be a fine powder which has been subjected to heat treatment in carbon tetrafluoride, or a moulded workpiece of crystalline material made from the powder and heat treated in carbon tetrafluoride. |
|
Method of diamond heat treatment Invention relates to processes used in operation at high pressure and modifying substances physically. Proposed method comprises placing diamond in reaction cell in pressure transmitting medium, increasing pressure in reaction chamber and it cooling. Note here that thermal treatment is carried out at temperature increase rate of 10-50°C/s and at 2000-2350°C by passing electric current via heater in cell from programmed power supply source with due allowance for temperature relaxation in said cell in heating. For this, note also that temperature relaxation constant is defined. Said cell is cooled after heating by switching off power supply in forming short diamond heating pulse in temperature range of over 2000°C with diamond total stay time smaller than 30 seconds. Allowance for temperature relaxation in said cell in heating for heating rate Vt and pre-definition of cell temperature relaxation constant τ is made by setting in said programmable power source the maximum temperature of heating to τVT above maximum treatment temperature of 2000-2350°C. |
|
Method of thermal treatment of abrasive tool (at) Invention relates to production of abrasive tools intended for machining metals and alloys. Proposed cycle of processing AT at TTB comprises heating AT at 2450 Hz in microwave chamber for near-100 mm-thick AT and at 890-915 Hz for over-100 mm-thick AT to complete polymerisation (hardening) and curing semis at said temperature with uniform forced removal of volatile matters released therefrom (hot vapor-gas mix) from thermostat free volume by airflow created by exhaust vent system of microwave chamber via slots made in thermostat front and rear walls to rule out saturation of said volatile matters. Temperature of processed semis is controlled by device incorporated with thermostat and airflow forced in thermostat is heated to temperature of semis. |
|
|
Invention relates to diamond processing, in particular, by thermochemical process. Proposed method comprises applying layer of spirit glue composition onto diamond surface, said composition containing transition metal, for example, Fe, Ni or Co, and processing diamond thermally at temperature not exceeding 1000°C. To prepare spirit glue composition, powder of water-soluble salt of transition metal is used. Said powder in amount of 1-10 wt % of water solution is mixed with spirit solution of glue at salt water solution-to-glue spirit solution ratio of 1:1. Prepared mix is applied on diamond surface in 10-20 mcm-thick layer to be dried. Thermal processing of diamond is performed in two steps. Note here that, at first step, diamond is processed at 600-700°C for 1-2 min, while, at second step, it is processed at 800-1000°C for 15-30 min. |
|
Method of producing fluoride nanoceramic Method involves thermomechanical processing of initial crystalline material made from metal halides at plastic deformation temperature, obtaining a polycrystalline microstructured substance characterised by crystal grain size of 3-100 mcm and intra-grain nanostructure, where thermomechanical processing of the initial crystalline material is carried out in vacuum of 10-4 mm Hg, thus achieving degree of deformation of the initial crystalline material by a value ranging from 150 to 1000%, which results in obtaining polycrystalline nanostructured material which is packed at pressure 1-3 tf/cm2 until achieving theoretical density, followed by annealing in an active medium of a fluorinating gas. The problem of obtaining material of high optical quality for a wide range of compounds: fluoride ceramic based on fluorides of alkali, alkali-earth and rare-earth elements, characterised by a nanostructure, is solved owing to optimum selection of process parameters for producing a nanoceramic, which involves thermal treatment of the product under conditions which enable to increase purity of the medium and, as a result, achieve high optical parameters for laser material. |
|
|
Procedure for surface of diamond grains roughing Procedure for surface of diamond grains roughing consists in mixing diamond grains with metal powder and in heating obtained mixture to temperature of 800-1100°C in vacuum as high, as 10-2-10-4 mm. As metal powders there are taken powders of iron, nickel, cobalt, manganese, chromium, their alloys or mixtures. Powders not inter-reacting with diamond grains at heating can be added to the mixture. |
|
Method of annealing crystals of group iia metal fluorides 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. |
|
|
Method of thermal treatment of single-crystal substrate znte and single-crystal substrate znte 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 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 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 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 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. |
|
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 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 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 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 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 mono-crystals of indium antimonide alloyed with tin Invention refers to process of production of AIIIBV semi-conducting compositions. Mono-crystals of indium antimonide alloyed with tin are produced by means of bombardment with a full specter of reactor neutrons with successive heating, annealing and cooling. Heating is carried out at the rate of 20÷40 deg/min to temperature of annealing, defined by the formula Tanneal=450+(tgNsn-14)-7 [°C], where Nsn is concentration of introduced alloying addition of tin [cm-3]; annealing is performed during 20 minutes, while the successive cooling is carried out at the rate of 5-10 deg/min to the temperature of 350÷400°C, and further at the rate of 20-40 deg/min to an ambient temperature. |
|
Mehgod of growing cadmium telluride monocrystal 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. |
|
Method of fabrication of mono crystal spinel plates (versions) Invention refers to fabrication of items with spinel crystal structure, including such items as boules, plates and bases, and also refers to active units comprising such items. According to one variant the method of fabricating mono crystal spinel plates includes the following operations: obtaining a portion of melt in a crucible, formation of spinel mono crystal boule out of melt at process coefficient of mould determined as ratio of medium diameter of the boule to interior diameter of the crucible and equal approximately to not less than 0.44, at that the boule has common formula aAD.bE2D3, where A is chosen from the group, which includes Mg, Ca, Zn, Mn, Ba, Sr, Cd, Fe as well as their combinations, and E is chosen from the group which includes Al, In, Cr, Sc, Lu, Fe and their combinations, and D is chosen from the group which includes O, S, Se and their combinations, at that the ratio b:a> 1.5:1, so the spinel is concentrated E2D3, and then cutting the boule into plurality of plates. Such items possess reduced mechanical stress which facilitates increased output of ready items. |
|
Invention is related to the field of coloured diamonds preparation, which are used, for instance, in decorative purposes. Method of coloured single crystal diamond transformation into different colour includes stages, at which coloured single crystal diamond is prepared by method of chemical depositing from steam phase (CDSP) and prepared diamond is thermally treated at temperature from 1200 to 2500°C and pressure that stabilises diamond, or in inert or stabilising atmosphere. Prepared single crystal may be shaped as thick layer or fragment of layer, which is cut as precious stone. |
|
Method of preparation of optically transparent single crystals of terbium-gallium garnet Invention is related to growing of garnets single crystals and may be used in laser equipment, magnet microelectronics (semi-conductors, ferroelectrics) and for jewelry purposes. Single crystals of terbium-gallium garnet are prepared by Chochralski method by means of melting primary stock, which includes clarifying calcium-containing additive, and further growing of single crystal from melt to primer. As primary stock mixture of terbium and gallium oxides is used, as calcium containing additive - calcium oxide or carbonate, and after growing crystal is annealed in atmosphere of hydrogen at temperature of 850-950°C for around 5 hours until orange paint disappears. |
|
|
Ultrahard diamonds and a method for preparation thereof Monocrystalline diamond grown via chemical precipitation from gas phase induced by microwave plasma is subjected to annealing at pressures above 4.0 GPa and heating to temperature above 1500°C. Thus obtained diamonds exhibit hardness higher than 120 GPa and crack growth resistance 6-10 Mpa n1/2. |
|
Method for preparing even-atom surface of gallium arsenide Method comprises steps of chemical-dynamic polishing of substrate surface in polishing etching agent containing sulfuric acid, hydrogen peroxide and water for 8 - 10 min; removing layer of natural oxide in aqueous solution of hydrochloric acid until achieving hydrophobic properties of purified surface of substrate; washing it in deionized water and drying in centrifuge. Then substrate is treated in vapor of selenium in chamber of quasi-closed volume while forming gallium selenide layer at temperature of substrate Ts = (310 -350)°C, temperature of chamber walls Tc = (230 - 250)°C, temperature of selenium Tsel = (280 - 300)°C for 3 - 10 min. After such procedure substrate is again placed in aqueous solution of hydrochloric acid in order to etch layer of gallium selenide. Invention allows produce even-atom surface of gallium arsenide at non-uniformity degree such as 3Å. |
|
Proposed method is used for coloring fianites (man-made diamonds) in green, blue and brownish-yellow colors; proposed method may be also used in optics for production of colored light filters withstanding temperatures above 1000°C. Proposed method includes preliminary application of cobalt on fianite surface to be colored and at least one metal whose oxide is liable to spinelle-forming with oxide of bivalent cobalt, iron and/or aluminum, for example. Then material is subjected to heat treatment in oxygen-containing atmosphere at temperature above 1000°C but not exceeding the fianite melting point. The procedure is continued for no less than 3 h. Coat is applied by thermal spraying of metals in vacuum. Said metals may be applied in turn and simultaneously. For obtaining bluish-green color of fianite, cobalt and aluminum are applied at atomic ratio of 1:1 to 1:2. For obtaining yellowish-green color, cobalt, aluminum and iron are applied at atomic ratio of 1:1 :0.1-0.2. For obtaining yellowish-brown color, cobalt and iron are applied at ratio of 1:1 to 1:2. |
|
|
Method comprises steps of acting upon crystal with electron beam whose integral flux is in range 5 x 1015 - 5 x 1018 electron/cm2; annealing crystal in temperature range 300 - 1900°C and acting with electron beam in condition of electric field having intensity more than 10 V/cm at least upon one local zone of crystal for imparting desired color tone to said zone. Local action of electron beams is realized through protection mask. As irradiation acts in condition of electric field local flaws such as bubbles or micro-inclusions are effectively broken. |
|
Method of thermal treatment of monocrystals of lanthanum-gallium silicate The invention is pertaining to the method of production of the crystals with the triclinic crystal system. Substance of the invention: the monocrystals of lanthanum-gallium silicate grown in compliance with Czochralski method from the iridium crusible are subjected to the two-stage thermal treatment. The monocrystals are preliminary subjected to the vacuum annealing at the pressure of 1·10-2 -1·10-4Pa and the temperature of 600-1200°C within 0.5-10 hours, and then conduct their isothermal air aging at the temperature of 300-350°C within 0.5-48 hours. The invention allows reproducibly produce the discolored monocrystals of lanthanum-gallium silicate and also to speed up propagation of the surface-acoustic waves (SAW) by 1-1.5 m\s at the simultaneous decrease of dispersion of the waves propagation velocity by 20-30 ppm. |
|
|
Method for treating colored diamonds and brilliants for decolorizing them and releasing stresses Method is realized due to physically acting in closed reaction space upon samples of diamonds and brilliants by means of high pressure and temperature for time period sufficient for enhancing their quality. Pressure acting upon samples is in range 6 - 9 GPa in region of thermodynamic stability. Temperature during physical action upon samples is in range 1700 - 2300°C. Samples are subjected to physical action in medium of graphite powder filling reaction space. Heating till high temperature is realized due to applying AC to samples of diamond or brilliant through graphite powder at specific electric current power from 0.18 kWt/cm3 and more. Then electric power is gradually increased from zero till working value and further it is decreased and increased at least two times for some time interval at each change of electric power. Process of annealing samples is completed by smoothly lowering electric current power till zero. At physical action upon sample electric current intensity is lowered by 11 - 13 % and it is increased by 15 - 17 % for time interval from 8 min and more at each change of electric power. Sample is AC heated and it is cooled at rate no more than 0.05kWt/min per cubic centimeter of reaction volume of chamber. |
|
|
Germanium monocrystal growing method Method comprises growing germanium monocrystals from melt onto seed followed by heat treatment, the latter being effected without removing monocrystals from growing apparatus at temperature within 1140 and 1200 K during 60-100 h, temperature field being radially directed with temperature gradient 3.0 to 12.0 K/cm. Once heat treatment comes to end, monocrystals are cooled to 730-750°C at a rate of at most 60-80 K/h. Monocrystals are characterized by emission scattering at wavelength 10.6 μm not larger than 2.0-3.0% and extinction not higher than 0.02-0.03 cm-1, which is appropriate for use of monocrystals in IR optics. |
|
|
Synthetic corundum contains alumina, color-forming additives and binder-paraffin. Required color is obtained as follows: for obtaining black color molybdenum oxide is added to alumina in the amount of 0.03%; for obtaining gray color, tungsten oxide is added to alumina in the amount of 0.01%; for obtaining blue color, neodymium oxide is added in the amount of 0.01%; for obtaining pink color, erbium oxide is added to alumina in the amount of 0.01%; for obtaining red color, chromium oxide is added in the amount of 0.05%. Proposed method of manufacture of jewelry articles includes molding in casting machines at a pressure of 4 atm and roasting; first roasting cycle is performed in continuous furnaces for burning-out the binder and is continued for 90 h at temperature of 1150 C; second roasting cycle is performed in batch furnaces at temperature of 1750 C and is continued for 170 h for forming and sintering of microcrystals making translucent crock at density of 4 g/cu cm and hardness of 9 according to Mohs hardness scale; then polishing is performed with the aid of diamond materials. Articles thus made have high-quality miniature texture at hardness which is disadvantage in relation to diamond only. |
Another patent 2551085.