Nanotubular materials crystallising in system of k2o-tio2-x-h2o (x=nio, mgo, al2o3, cr2o3, co2o3, fe2o3) and method of their synthesis

FIELD: chemistry.

SUBSTANCE: nanotubular materials crystallising in the system of K2O-TiO2-X-H2O (X=NiO, MgO, Al2O3, Cr2O3, CO2O3, Fe2O3) are characterized by the fact that in their composition up to 10% of ions Ti4+ is replaced by doping two- or trivalent metal. The method of synthesis of nanotubular materials is characterized by the fact that the synthesis of the samples is carried out by hydrothermal treatment of a pre-prepared mixture of hydroxide in KOH solution, to produce the initial mixtures of hydroxides, a solution of titanyl chloride synthesised by reaction of TiCl4 with chilled distilled water, is mixed with aqueous solutions of salts of finished elements in a predetermined ratio, and then the precipitation of hydroxides is produced by adding NH4OH to the aqueous solution mixture at pH=9-9.5 followed by washing with distilled water, drying at 70-90°C and mechanical crushing, then the crushed precipitate is mixed with 10 M KOH solution and subjected to a hydrothermal treatment at 170-180°C for, at least, 24 hours, after which the resulting product is washed with distilled water.

EFFECT: invention makes it possible to synthesise potassium-titanate nanotubes with an average outer diameter of 5 to 12 nm.

2 cl, 5 dwg, 2 ex

 



 

Same patents:

FIELD: process engineering.

SUBSTANCE: invention relates to production of high-purity long silicon substrates for fabrication of solar batteries. Proposed method is implemented in process reactor including green silicon 1, shaper 4 with hole 5, induction heater 3 that makes silicon melt 2 column above shaper 4 and silicon seed 6 fed into shape hole from below. Note here that oxygen-bearing atmosphere is created in said reactor. Silicon melt is alloyed with oxygen to create oxygen complexes to control specific resistance of silicon substrates 9. At a time with alloying silicon dioxide film 13 is formed on silicon melt 2 surface to increase melt surface tension and to decrease growth angle. Silicon substrates 9 are formed by quartz shaper 4 and cooled by direct dipping in cooling fluid 10, for example, deionised water and/or cooling fluid vapours. Reactor requires no sealing.

EFFECT: production of silicon substrates with adjustable specific resistance, higher stability, accelerated process, lower costs.

28 cl, 6 dwg

FIELD: metallurgy.

SUBSTANCE: invention relates to the technology of growing of pipes from single crystals of high-melting metal oxides and their solid solutions: sapphire, aluminium-magnesium spinel, aluminium-yttric garnet, and can be used in various areas of science and engineering, where the high-tensile, inert and thermostable pipes are required. The device includes the crucible consisting of axially located, made from molybdenum the external pipe 1 and, at least, one internal pipe 2, molybdenum cover 7, fixed from above, and collet 3, located in the bottom of the crucible, on which the external 1 and internal 2 pipes and cylindrical single-crystal seed crystal 4, having, at least, one channel 5 for placing in it of internal pipe 2, are fixed. The initial mix material 6 is placed in the specified device, where it is placed between external and internal pipes of the crucible and melted in the unit of vertical unidirectional solidification at the level of isothermal curve of crystallization with the movement of the crucible up, the melt is held in the top position no less than 2 hours and crystallization is performed at the level of isothermal curve at a rate of no more than 5 mm/hour.

EFFECT: invention allows to obtain single-crystal pipes of the specified size and high quality moulds without bubbles and blocks.

5 cl, 1 dwg

FIELD: chemistry.

SUBSTANCE: one of the versions of producing silicon filaments in form of rods and/or substrates with an arbitrary cross-section from high-purity silicon involves continuous fusion casting of silicon downwards on a seeding agent through a draw plate situated between the melt zone and an inductor in an atmosphere of oxygen, cooling the obtained filament by immersion in a coolant, wherein seeding is carried out below the plane of the draw plate; the level of the coolant is set and kept near the crystallisation front, and the crystallisation front of silicon rods and/or substrates is held below the plane of the draw plate at a distance of 0.5-20 mm.

EFFECT: obtaining silicon filaments characterised by low electrical resistance, which are subject to heating when transmitting electric current at industrial frequency through said filaments from a low-voltage source, while maintaining a high rate of casting, as well as stable plastic and geometric characteristics of the finished product.

2 cl, 1 dwg

FIELD: metallurgy.

SUBSTANCE: method involves preliminary installation in lower part of a melting pot of fuse providing crystallisation of end product, charging of the cavity of the melting pot with raw material consisting of sand grains so that there provided is continuous supply to the cavity of the melting pot of new additional portions of raw materials from the volume of the additional tank, which is interconnected with it and isolation of the melting pot cavity with monocrystal being formed in it from outside environment, and treatment of raw material with artificially created physical field at constant rotation of the melting pot with the crystal being formed in its cavity about its longitudinal axis, at the pressure, the value of which does not correspond to the value of atmospheric one. Besides, silicon oxide particles are used as initial raw material, which are obtained by crushing of sand grains to the size of 1-8 mcm, which are contained in the air suspension formed in the melting pot cavity in the volume of 40-60%, and as artificially created physical field - rotating alternating magnetic field, the intensity of which in conversion zone of initial raw material is 1×105÷1×107 A/m, and frequency is 40-70 Hz, treatment of raw material is performed in the melting pot consisting of three independent parts: upper detachable part being a raw material tank; a serviceable melting pot that is immediately intended for growth of monocrystals, the cavity of which is interconnected with the tank volume; and lower detachable part attached to lower part of the serviceable melting pot, which is intended for collection of wastes formed in it during treatment, and namely slags and granules of silicon, which is interconnected with its inner volume through calibrated orifices made in a detachable partition wall. Besides, to the cavity of the serviceable melting pot there constantly supplied are compressed air jets under excess pressure of 0.1-0.6 kgf/cm2, and rotation of the melting pot is performed during 54-72 minutes at two stages, at the first one of which the rotation axis constantly keeps vertical orientation; and at the second stage the above axis changes its initial position from time to time by being diverted from it through the earlier specified angle of 5-15°. The melting pot performs the function of a closing connecting link for the system generating alternating magnetic fields.

EFFECT: invention allows obtaining monocrystals of columnar shape from common sand that requires no additional preparatory operations related to its cleaning or benefication.

2 cl, 2 dwg

FIELD: metallurgy.

SUBSTANCE: reactor comprises cooling tray 1 mounted on a supporting structure, cylindrical cover 2, consisting of three inner cooling jacket and outer cooling jacket 4, cooling guide ribs 5. Outer cooling jacket 4 consists of the segments, which are rigidly connected to each other and by the agency of cooling guide ribs 5 of inner cooling jacket 3 by welding. The structure is provided with means for supply 7 and offtake 8 of cooling environment and bulkhead 9 for attaching the cover to tray 1. Between outer cooling jacket 4, internal cooling jacket 3 and guiding ribs 5 the ring channels are formed, passing from one level to another in a spiral.

EFFECT: reduced weight of the reactor containment and improved cooling conditions of internal jacket.

5 dwg

FIELD: metallurgy.

SUBSTANCE: initially, treated tubular stock 4 out of tungsten is assembled on lower support tube 2 of holder, then circular inoculating crystal 7 with known orientation of growth axis is arranged on upper part of tubular stock 4 and it is secured to treated tubular stock 4 and to upper support pipe 8 of holder; further tubular stock 4 with inoculating crystal 7 is fixed in holder by means of central support rod 3 and support shaft 1 with circular groove for its centering; then treated tubular stock 4 is subjected to preliminary vacuum annealing at before-melting temperatures directly in vacuum melting chamber. Further there is performed growth of tubular crystal 6 on circular inoculating crystal 7 of 10 mm height by means of treatment of the tubular stock with zone re-melting under effect of electronic beam onto contact region between the circular inoculating crystal and the treated tubular stock, simultaneously rotating the treated tubular stock around axis passing through the holder, when a source of electrons moves along the growing tubular crystal 6 along the whole length of the treated tubular stock 4.

EFFECT: massive tubular crystals of tungsten with upgraded structure quality and increased output of finished products.

2 cl, 1 ex, 3 dwg

FIELD: technological processes.

SUBSTANCE: invention is related to the field of electronic engineering, in particular to technology for growth of profiled single-crystals of silicon in the form of hollow thin-walled cylinders to make epitaxial cylindrical (non-planar) structures of strong power semiconductor instruments. Method consists in the fact that vacuum chamber is sealed and vacuumised with thermal unit and hollow cylindrical seeding agent of silicon single crystal located in it, inertial gas with dew point of at least -70°C is supplied in it during the whole process of hollow cylindrical single crystals growth, heater is used to heat the thermal unit equipped with quartz melting crucible filled with silicon, afterwards quartz melting crucible is vertically displaced until its bottom is located in zone of thermal unit maximum temperature, and silicon fill is melted, then lower end of hollow cylindrical seeding agent of silicon single crystal is melted by means of its submersion into silicon melt located in quartz melting crucible, afterwards quartz melting crucible and hollow cylindrical seeding agent of silicon single crystal in contact with silicon melt are rotated in the same direction and with the same rotation frequency, at that rotary hollow cylindrical seeding agent of silicon single crystal is lifted up with speed that provides for growth of hollow cylindrical single crystal of silicon on its lower end, to complete expenditure of silicon melt in quartz melting crucible, at that in process of growing the following conditions are fulfilled: qint.=qext., where qint. is specific thermal flow directed to internal surface of hollow cylindrical silicon single crystal in process of its growth in crystallisation plane, W/m2, qext. is specific thermal flow directed at external side surface of hollow cylindrical single crystal of silicon in process of its growth in crystallisation plane, W/m2, and convective flows of silicon melt are directed from center of quartz melting crucible bottom vertically upwards along axis of hollow cylindrical seeding agent of silicon single crystal. Design of device for growth of hollow cylindrical silicon single crystals is described.

EFFECT: formation of section of profile hollow cylindrical silicon single crystals with uniform distribution of their electrophysical and structural parametres: diametre of 20-50 mm with continuous thickness of wall of 3-5 mm and low density of dislocation in structure - not more than 103-104 cm-2, specific electric resistance of 0.02 Ohm·cm with dispersion of not more than 6%, life time of unbalanced charge carrier of not more than 1 mcs.

4 cl, 1 dwg

FIELD: chemistry; profiled silicon monocrystals manufacturing.

SUBSTANCE: silicon monocrystals are produced by crucible-free vertical float-zone method, which implies induction generation of a melt drip on initial vertical silicon ingot, seeding of monocrystal being grown on a seed [111] oriented silicon monocrystal, building-up of crystal conical portion to specified diameter, while moving initial ingot and coil in horizontal plane, under conditions, which provide for convex crystallisation front, and emergence of face (111) at melt centre surface at the moment the monocrystal specified diameter is reached. This is followed by hollow monocrystal growing, melt column, which connects the melt ring resting on the growing monocrystal with the drip on initial ingot, being positioned between edge of (111) face and cylindrical surface of the growing monocrystal.

EFFECT: production of silicon hollow (tubular) dislocation-free high-purity perfectly structured monocrystals with [111] orientation.

3 dwg

The invention relates to the technology of electronic instrumentation, and in particular to methods of dimensional profiling of crystals of silicon carbide, and can be used in Microsystems technology, optoelectronics, etc

The invention relates to techniques for growing shaped crystal pulling from the melt with rotation using formers and can be used to produce monocrystalline tubes and rods with periodically varying impurity content along the length of the crystal

FIELD: chemistry.

SUBSTANCE: invention relates to the field of the chemical technology of growing sodium-bismuth molybdate NaBi(MoO4)2 crystals for the research of physical properties and practical application. The monocrystals NaBi(MoO4)2 are grown by crystallisation from a high-temperature solution in a charge melt, which contains sodium-bismuth molybdate and a solvent sodium dimolybdate in a ratio, equal to 10-30:90-70 mol% respectively, crystallisation is carried out on inoculum, oriented perpendicularly to dipyramide edges [101], with the inoculum revolving at a rate of 10-30 rev/min and a rate of extension of 1-5 mm/day, with constant cooling of the solution-melt at a rate of 0.5-15 degrees/day, with growing being carried out under conditions of low gradients ΔT/Δl lower than 1 degree/cm in the solution-melt.

EFFECT: method makes it possible to obtain colourless, stoichiometric in the structure, large (size 75×30 mm), optically homogenous NaBi(MoO4)2 crystals.

1 ex

FIELD: chemistry.

SUBSTANCE: invention refers to chemical technology and concerns manufacturing crystals of rubidium-bismuth molybdate RbBi(MoO4)2. The crystals RbBi(MoO4)2 are grown from a high-temperature solution in melted charge containing rubidium dimolybdate and triple lithium-rubidium-bismuth molybdate LiRbBi2(MoO4)4, in ratio of the latter toribidium dimolybdate equal to 10-40: 90-60 mole %, respectively; fuse crystallisation is focused in the direction [001], with a fuse rotation at 30-65 rpm and pulling rate 0.3-1.0 mm/day with cooling the melted solution at 0.2-1.0 degrees/day; the growing process in performed in the environment of low gradient ΔT less than 1 degrees/cm in the melted solution.

EFFECT: invention enables producing the coarse crystals RbBi(MoO4)2 of high optical quality.

1 ex

FIELD: chemistry.

SUBSTANCE: invention relates to field of chemical technology, namely to growing crystals of potassium-barium molybdate K2Ba(MoO4)2 from solution-melt of K2Ba(MoO4)2 for analysis of physical properties and practical use. As solvent used is potassium molybdate K2MoO4, with molar ratio of potassium-barium molybdate and potassium molybdate K2MoO4, equal 1:2, respectively, crystallisation is carried out on seed, increased from 1 to 2 mm/day and rotating at rate 30-40 rev/min, oriented by direction [001], cooling of melt is carried out at rate from 0.2 to 3 degrees/day, with cooling of crystals being carried out at rate 20 degrees/day.

EFFECT: claimed method makes it possible to obtain optically homogenous K2Ba(MoO4)2, crystals of large size (25×15 mm) without inclusions, blocks and cracks.

1 ex

FIELD: chemistry.

SUBSTANCE: invention relates to field of chemical technology and deals with obtaining volumetric crystals with composition Li8Bi2(MoO4)7. Crystals are grown from solution-melt of lithium-bismuth molybdate in solvent by crystallisation with gradual cooling of melt and grown crystals, and as solvent used is eutectic mixture, containing 47 mol.% of molybdenum oxide and 53 mol.% of lithium molybdate with content of lithium-bismuth molybdate and eutectic mixture equal 10-40 mol.% and 90-60 mol.% respectively, growing is performed under conditions of low temperature gradients, constituting less than 1 grad/cm, on primer, oriented by [001] and rotating at rate 20-30 rev/min with pulling rate 0.5-2.0 mm/day with constant cooling of solution-melt at rate 0.2-5.0 degree/day with further separation of grown crystals from solution-melt and cooling them to room temperature.

EFFECT: invention makes it possible to obtain large (with size 20÷30 mm) Li8Bi2(MoO4)7 crystals of high optic quality.

1 ex

FIELD: chemistry.

SUBSTANCE: invention relates to the technology of growing lithium-magnesium molybdate Li2Mg2(MoO4)3 crystals. The method involves melting lithium-magnesium molybdate in a molten solvent, crystallising while cooling the melt and cooling the grown crystals, wherein the solvent used is lithium molybdate Li2MoO4 with molar ratio of lithium-magnesium molybdate to lithium molybdate Li2MoO4 of 2:3, respectively; crystallisation is carried out on an inoculating crystal revolving at a rate of 35 rpm, oriented on the [010] direction, rate of drawing rate of the inoculating crystal of 1-3 mm/day while simultaneously cooling the melt at a rate of 0.2-5 degrees/day and then separating the grown crystals from the melt and cooling at a rate of 30 degrees/hour.

EFFECT: method enables to obtain optically homogeneous lithium-magnesium molybdate crystals which do not contain inclusions, blocks and cracks.

FIELD: metallurgy.

SUBSTANCE: invention refers to growth from molten metal of non-alloyed crystals of sodium tungstate-bismuth NaBi(WO4)2 being perspective material for Cherenkov detectors. Growth of crystals is performed using Chokhralsky method in air atmosphere at drawing speed of 4-5 mm/hour and crystal growth speed of 15-19 min-1.

EFFECT: method allows obtaining crystals transparent in visible range beginning from wave length of 352 nm.

3 dwg, 4 ex

FIELD: physics.

SUBSTANCE: optical medium for converting monochromatic laser radiation with wavelength 975±5 nm to the 1483-1654 nm band is a complex calcium tetragermanate of erbium and yttrium of formula ErxY2-xCaGe4O12, where 0.1<x<0.3. The method of making the said optical medium involves preparation of two initial mixtures of components containing the following in wt %, respectively: calcium carbonate - 11.11; erbium oxide - 42.45; germanium oxide - 46.43 and calcium carbonate - 13.45; yttrium oxide - 30.34; germanium oxide - 56.21. Separate mixing of components of each mixture is carried out in the presence of an alcohol, as well as heating to 700-900°C and maintaining that temperature for 8-10 hours. Repeated heating is carried out to 1050-1100°C, while maintaining that temperature for 100-150 hours and reburdening every 20 hours. Both initial mixtures are then mixed in ratio of 1:4.6-15.3 in the presence of an alcohol and heating to 1050-1100°C and maintaining that temperature for 40-50 hours and reburdening every 10 hours.

EFFECT: possibility of converting monochromatic radiation into a band with simultaneous amplification during operation of the laser in continuous pumping mode.

2 cl, 3 dwg, 2 ex

FIELD: chemistry.

SUBSTANCE: invention relates to growing high-temperature inorganic monocrystals and can be used in quantum electronics and elementary-particle physics, in particular for neutrinoless double beta decay detectors. The said monocrystals are grown by pulling zinc molybdate crystals ZnMoO4 from molten initial charge in a melting pot for inoculation. The initial charge used is a mixture of oxides ZnO and MoO3, taken in stoichiometric ratio with excess MoO3 in amount of 1.0-7.0 wt %, and growth takes place at crystallisation volume rate of over 0.4 cm3/h. Using Czochralski growth method, pulling rate is 0.3-3.0 mm/h with axial temperature gradient at the crystallisation front of 80-100°/cm. Using Kyropoulos growth method, pulling rate does not exceed 0.5 mm/h while maintaining crystal diametre of 80-95 % of the diametre of the melting pot.

EFFECT: proposed method allows for obtaining large monocrystals (size of 1 cm3 or more), with optical properties suitable for use as scintillation detectors and optical elements.

3 cl, 2 ex, 2 dwg

The invention relates to methods of obtaining crystals, namely the method of producing single crystals of lead tungstate, and can be used in the manufacture of scintillation elements

FIELD: metallurgy.

SUBSTANCE: invention relates to methods for obtaining colloids of a metal oxide (versions), namely silicon dioxide, as well as to colloids themselves. The method involves addition of a chemically active metal oxide to a reaction tank at optimum mass velocity of addition of the metal oxide, which is based on a mathematical model that considers (i) particle nucleation rate, (ii) rate of metal oxide deposition on existing particles of metal oxide and (iii) growth of metal oxide particles in the reaction tank. Mass velocity of addition of metal oxide increases as a reaction time function. Introduction of inoculating particles of metal oxide to the reaction tank is performed prior to a stage of addition of the chemically active metal oxide. An optimum mass velocity of addition of metal oxide q is presented by the following formula: q=(3moGr/Dpo3)(Dpo+Grt)2, where: mo represents mass of metal oxide particles in the reaction tank in grams; Gr represents growth rate of metal oxide particles for metal oxide particles in the reaction tank as is determined as per increase of particle diameter, in nanometres per hour; Dpo represents average diameter of metal oxide particles in nanometres; t represents time in hours. Gr is within approximately 10 to approximately 50 nm/hours and q is within approximately 10.6 to approximately 52.8 g/1000 m2-hour during at least some part of the reaction period.

EFFECT: methods according to the invention are more effective due to reduction of reaction periods necessary to obtain colloids of metal oxide.

25 cl, 5 dwg, 1 ex

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