Method of synthesising monocrystalline iron selenides
SUBSTANCE: invention can be used for laboratory and industrial production of monocrystalline materials. A method of synthesising tetragonal iron monoselenide includes heating a hermetic vial with a charge from selenium and iron placed in one of its ends and filled with a salt melt. The vial heating is performed with the temperature gradient from a value of 450°C-350°C from the side of the charge location to a temperature, reduced by 30°C-100°C from the opposite side. As the salt melt used are mixtures of eutectic composition, which includes aluminium chloride. Heating is performed for the time necessary for the transfer of the selenium and iron charge into the opposite end of the vial.
EFFECT: invention makes it possible to increase coarseness of FeSe crystals with reduction of their synthesis temperature.
2 cl, 1 dwg, 4 ex
The invention relates to inorganic chemistry, namely, to technology creation and processing of crystalline materials, which is included in the list of critical technologies of the Russian Federation, namely the laboratory and the industrial production of monocrystalline iron selenides, including superconducting tetragonal FeSe1-x.
The prior art synthesis of Fe-Se from melts when the crystals grow when you own cooling of the melt (V. Tsurkan, J. Deisenhofer, A. Günther, Ch. Kant, H.-A. Krug von Nidda, F. Schrettle, A. Loidl, European Physical Journal 79, 2011, 289.) The disadvantage is the high temperature synthesis, in which the most unstable substances, or have a faulty structure, and/or a large deviation from the equilibrium conditions caused by the cooling of the starting substances.
The known method of synthesis of single-crystal iron selenides using the method of gas transport, when the mixture is added a small amount of transport of the reagent (catalyst), and a crystal grows from the gas phase in the temperature gradient. (A. Serafin, A.I. Coldea, A.Y. Ganin, M.J. Rosseinsky, K. Prassides, D. Vignolles, and A. Carrington, Phys. Rev. 82, 104514, 2010).) However, this method also does not work for phases stable at low temperature.
Known for the synthesis of single crystals in the molten tin with diluted Fe and Se during slow cooling. (N. Ni, S.L. Bud'ko, A. Kreysig, S. Nandi, G. E. Rustan, A.I. Goldman, S. Gupta, J.D. Corbett, A. Kracher, and P.C. Canfield, Phys. Rev. 78, 014507, 2008.) The disadvantage of this method is the difficulty of separating tin from the fusion products and the gradual change of temperature synthesis of single crystals in the growth process, which leads to a gradual change of properties of single crystals (zoning).
Closest to the claimed technical solution is the method of synthesis of single crystals in the molten halide salts of alkali metals with dissolved therein Fe and Se during slow cooling. As the environment using a combination of chlorides of alkali metals. (R. Hu, N. Lei, M. Abeykoon, E.S. Bozin, S.J.L. Billinge, J.B. Warren, T. Siegrist, and C. Petrovic, Phys. Rev. 83, 224502, 2011.) The disadvantage of this method is the gradual change of temperature synthesis of single crystals in the growth process, which leads to a gradual change of properties of single crystals (zoning). In addition, most of chlorides of alkali metals crystallizes at temperatures apparently higher temperature stability of iron selenides, in particular superconducting FeSe.
The task and the technical result of the invention are to develop technologies that provide larger crystals FeSe decreasing the temperature of synthesis.
The problem is solved in that in the method of synthesis of iron selenides, including heat seal technics is Oh ampoule placed in one end of the mixture of selenium and iron, and filled with a salt melt, according to the invention, heating of the ampoule is performed with the temperature gradient of the value 450-350°C by placing the mixture to a temperature of minus 30 to 100°C from the opposite side, where the molten salt is a mixture of eutectic composition comprising aluminum chloride, and heating is carried out over time, providing transfer of the charge from selenium and iron in the opposite end of the ampoule. As the molten salt may be used a mixture of aluminium chloride and potassium chloride in a molar ratio of 1.5-2:1.
Thus, the technical result is achieved due to the use of the new method of synthesis, including the creation of certain conditions of the synthesis of crystals, when growth occurs during the migration of selenium and iron in salt eutectic under the action of the temperature gradient from the hot end to the cold. The temperature gradually decreases with distance from the hot end of the ampoule to the cold. In this respect, the temperature of the interval is significantly below the temperatures that are used in the known methods. This is achieved through the use of a transport medium low-melting molten salt with the participation of aluminium chloride.
The invention is illustrated by the drawing, which shows a circuit implementation of the invention. Position the s in the figure is displayed: 1 - the single crystals of iron selenides, 2 - vial, 3 - molten salt, 4 - oven, 5 - hot end of the ampoule, 6 - cold end of the ampoule, 7 - mixture of iron and selenium.
The method can be implemented using the device represented in the figure.
The growth of crystals 1 occurs in a sealed ampoule 2, filled with a salt melt 3, under conditions of high temperature exposure. Synthesis in sealed quartz glass can be implemented similarly to the method presented in the source of information - Kullerud, G. Experimental techniques in dry sulfide research. In: Ulmer, G.C. (ed.) Research Techniques for High Pressure and High Temperature, Spinger-Verlag, New York, pp.288-315 (1971). Synthesis in executions salts described in Moh GH, Taylor L.A., Laboratory techniques in experimental sulfide petrology. Neues Jahrb. Mineral. Monatsch. 1971, No 10, 450-459. The ampoule is placed in a furnace 4 in a horizontal position and creates a temperature gradient. Crystal growth occurs in the temperature gradient, the temperature of the "hot" end of the 5 ampoules, which initially have a mixture of selenium and iron 7 is 450-350°C, the temperature of the "cold" end of the 6 - 30-100°C below the temperature of the "hot" end. As the molten salt is a mixture of eutectic composition (or close to eutectic) with the obligatory presence of aluminium chloride. The mixture of selenium and iron in the process of "gradient" temperature effects (smooth continuous reduced the I temperature of the "cold" end of the ampoule to its hot end) is gradually transferred from the hot end of the ampoule in the "cold" end of the lower solubility of selenium and sulfur in salt melt when cooled. The growth of the crystals is not less than one month.
This method was tested at different temperatures:
Example 1. Capsules long 100 mm, an inner diameter of 8 mm quartz glass was filled with a mixture of 1000 mg of selenium, 700 mg of iron and were first covered with aluminium chloride and potassium chloride in a molar ratio of 2:1. The ampoule was sealed under vacuum and placed in a tube furnace resistance handmade at the temperature of 400°C for 3-4 weeks. The temperature gradient was provided by the proximity of the "cold" end of the ampoule to the edge of the furnace. The temperature of the cold end was 350°C. the samples were obtained FeSe single crystals with dimensions of at least 2×2×1 mm with a well-formed habit.
Example 2. Capsules of the same size with the same filling were placed in the same oven with a temperature of 457°C in the hot end and at a temperature of 400°C with a temperature at the cold end. The synthesis was continued for 21 days. This has resulted in a sample size of 1×1×0.5 with poorly formed by habit and probably with ferromagnetic impurity.
Example 3. Quartz ampoules of the same size with similar Fe/Se charge and eutectic mixture of AlCl3/NaCl/KCl were placed in the same oven temperature to 300°C at the hot end, and a temperature of 270°C at the cold end. The synthesis was continued for 45 days. As a result, cold to the price of the capsules were found only slight traces of powder FeSe.
Example 4. Quartz ampoules of the same size with similar Fe/Se charge and eutectic mixture of AlCl3/NaCl/KCl/AgCl (used a mixture of aluminium chloride, potassium chloride and sodium chloride in an approximate molar ratio of 1.5-2:1:1.) were placed in the same oven at a temperature of 360°C at the hot end, and a temperature of 280°C at the cold end. The synthesis was continued for 60 days. This has resulted in samples of FeSe single crystals with dimensions of not less than 1×1×0.2 mm to form a habit.
Thus, on the basis of these experiments, it was concluded that the optimum crystal growth is observed at the temperature of the hot end 450-350°C and the temperature of the cold end at 30-100 degrees below.
1. The method of synthesis of tetragonal monoselenide iron, comprising heating the sealed ampoule is placed in one end of the mixture of selenium and iron and filled with a salt melt, characterized in that the heating of the ampoule is performed with the temperature gradient on the value of 450°C-350°C by placing the mixture to a temperature of minus 30°C-100°C on the opposite side, where the molten salt is a mixture of eutectic composition comprising aluminum chloride, and heating is carried out in the course of time, providing transfer of the charge from selenium and iron in the opposite end of the ampoule.
2. The method according to claim 1, trichosis fact, as molten salt, a mixture of aluminium chloride and potassium chloride in a molar ratio (1.5 to 2):2.
SUBSTANCE: method involves controlling temperature of a diamond growth surface so that all temperature gradients on the said surface do not exceed 20 єC, and growth of a monocrystalline diamond on the said surface through chemical gas-phase deposition in a microwave plasma at growth temperature in a deposition chamber, the atmosphere of which contains approximately 8-20% CH4 per unit H2 and approximately 5-25% O2 per unit CH4. Diamonds larger than 10 carat may be obtained using the method, which is the subject of the present invention.
EFFECT: faster diamond growth.
29 cl, 1 ex, 11 dwg
SUBSTANCE: device for deposition of particularly crystalline layers onto at least one particularly crystalline substrate with technological chamber 5 arranged by several wall parts 1, 2, 3, 4, wall parts 1, 2, 3, 4 of which are electroconductive and join with each other to make contacts 2', 2", 3', 3", with reactor body 6 made of non-electroconductive material and including wall parts 1, 2, 3, 4 of technological chamber, and with heating coil 7 of high frequency that surrounds wall parts 1, 2, 3, 4 of technological chamber, comprises massive screening heating tube 8 arranged between reactor 6 body and walls 1, 2, 3, 4 of technological chamber as a whole part, material of which is electroconductive to such an extent that it heats from vortex currents induced by high-frequency field generated by means of high-frequency coil 7, significantly suppresses high-frequency field and surrounds technological chamber 5 so that wall parts 1, 2, 3, 4 of technological chamber are heated with the help of heat radiation.
EFFECT: invention makes it possible to prevent local heating in the area of contact zones of separate wall parts of technological chamber, which provides for an even temperature profile inside of it.
14 cl, 5 dwg
FIELD: carbon particles.
SUBSTANCE: invention relates to technology of preparing particles having monocrystalline diamond structure via growing from vapor phase under plasma conditions. Method comprises step ensuring functioning of plasma chamber containing chemically active gas and at least one carbon compound and formation of reactive plasma, which initiate appearance of seed particles in the plasma chamber. These particles ensure multidirectional growing of diamond-structured carbon thereon so that particles containing growing diamond are formed. Functioning of plasma chamber proceeds under imponderability conditions but can also proceed under gravitation conditions. In latter case, seed particles and/or diamond-containing particles in reactive plasma are supported under effect of external gravitation-compensating forces, in particular by thermophoretic and/or optic forces. Temperature of electrons in the plasma are lowered by effecting control within the range from 0.09 to 3 ev. Chamber incorporates plasma generator to generate plasma with reduced electron temperature and device for controlling forces to compensate gravitation and to allow particles to levitate in the plasma with reduced electron temperature. This device comprises at least one levitation electrode for thermophoretic levitation of particles in plasma with reduced electron temperature or an optical forceps device.
EFFECT: enabled efficient growing of high-purity duly shaped particles with monocrystalline diamond structure having sizes from 50 μm to cm range (for instance, 3 cm).
19 cl, 5 dwg
SUBSTANCE: invention relates to technology of high-temperature synthesis of gold and silver chalcogenides, namely, Ag3AuX2, where X=S, Se - utenbodaardtite (α-Ag3AuS2) and fishesserite (α-Ag3AuSe2). Au-Ag chalcogenides are produced from high-temperature melts of stoichiometric composition of a mixture of elementary components taken at ratios corresponding to the synthesized composition with excess of chalcogen in the amount of at least 0.04 wt % from the total charge. The mixture of elementary components is placed into a quartz lamp equipped with a rod to minimise its free volume, the ampoule is sealed and vacuumised, the mixture is heated higher than temperature of synthesized compound melting with the speed of 0.2-0.5°C per minute, sustained at this temperature to produce a homogeneous melt, the melt is cooled down to the temperature below the melting temperature of the produced compound with the speed of 0.2°C per minute, the produced compound is annealed at this temperature, then ampoule is cooled down to ambient temperature.
EFFECT: invention makes it possible to produce a microcrystalline sulphide or selenide of gold and silver of a homogeneous composition, and also provides for explosion-proof conditions of their production.
2 dwg, 1 ex
FIELD: machine building.
SUBSTANCE: device consists of heater 3 and cooler arranged to create gradient of temperature in crystalliser 1. Cooler 22 consists of heat exchanger 17 and controlled additional heat source 18. Also, the latter includes induction coil 10 and current conducting susceptor 11 positioned between crystalliser 1 and induction coil 10. A module including induction coil 10 and its cooling contour 21 containing liquid circulating in induction coil 10 forms heat exchanger 17. The procedure consists in heating crystalliser 1 from top with heat source 3 and in control of heat removal from crystalliser 1 from beneath by means of heat exchanger 17 and controlled additional heat source 18.
EFFECT: efficient control of temperature and reduced cost of disclosed device.
11 cl, 4 dwg
SUBSTANCE: one of versions is disclosed in procedure for production of cast silicon consisting in contacting melt silicon with at least one seeding crystal of silicon in vessel with one or several side walls heated at least to temperature of silicon melting; also, there is at least one cooled wall. Further, the procedure consists in formation of solid massif of mono-crystal silicon, not necessarily, with at least two dimensions, each at least approximately 10 cm by cooling melted silicon with control of crystallisation. Also, formation of massif includes formation of interface of solid with liquid along rib of melted silicon which at least first is parallel to at least one cooled wall. Interface is controlled during cooling so, that it is transferred in the direction where distance between melted silicon and at least one cooled wall increases. There is produced cast massif of silicon of large dimension (for example, ingots with area of cross section of at least 1 m2 and up to 4-8 m2) not containing or practically not containing radially distributed impurities and oxygen induced defects of packing.
EFFECT: more fast, efficient and less expensive procedures facilitating control of dimension, shape and orientation of grains of crystal in cast massif of crystallised silicon.
34 cl, 9 dwg, 3 ex
SUBSTANCE: crystalliser consists of main case with surface of base and side walls forming internal volume. According to the present invention the main case contains at least 65 % in weight of silicon carbide and from 12 % to 30 % in weight of a component chosen from the group including silicon dioxide or nitride. Notably, the main case contains at least one cover out of dioxide and/or nitride of silicon at least of surfaces forming internal volume of the crystalliser. As main component of the crystalliser there is used silicon carbide with crystallographic phase not subjected to phase transformation at temperature of melted silicon treatment, which facilitates solving the problem of uniformity loss of transfer/withdrawal of energy existent in common crystallisers. Additionally, silicon carbide does not have plastic phases under such temperature and consequently, is not subjected to deformation.
EFFECT: repeated usage of crystalliser without visible deterioration of its physical integrity.
9 cl, 1 tbl
SUBSTANCE: here is disclosed procedure for production of at least one mono-crystal nucleus acceptable as seed at fabrication of high pressure mono-crystal guiding nozzle unit of turbo-machine with at least one blade between two platforms by metal casting. The procedure consists in making wax pattern 10 containing first element 11 forming a pattern of the guiding nozzle unit, second element 13 forming pattern of seed and containing a flat shear of localisation of crystal orientation, and at least third element 14 including pattern 14A of source nucleus with a flat shear of localisation of crystal orientation. There is formed a ceramic case casting mould on base of the said wax pattern 10 and there is introduced seed containing the said flat shear of localisation of crystal orientation into a casting mould. Metal is cast into a mould. Oriented crystallisation of metal in the cast mould on base of seed is carried out so, as to facilitate the same crystallographic structure of produced source nucleus as of the part. Produced source nucleus is separated from the part for further usage as seed.
EFFECT: simplified production of nuclei, thus reducing cycle of parts fabrication; essential reduction of their prime cost.
9 cl, 4 dwg
SUBSTANCE: crucible 1 for crystallisation of silicon consists of base 2 with lower surface 21 and side walls 22, forming internal volume, and of protecting coating 3 containing from 80 to 95 wt % of silicon nitride and from 5 to 20 % of low temperature mineral binding material at complete contents of oxygen within range from 5 to 15 % in weight.
EFFECT: protective coating can be applied fast and efficiently, is more durable and possesses improved cohesion with crucible walls.
13 cl, 2 tbl, 1 dwg
FIELD: machine building.
SUBSTANCE: crucible for silicon crystallisation consists of main case 2 having bottom surface 21 and side walls 22 creating internal volume, of substrate 25 containing from 80 to 100 wt % of silicon nitride and positioned near surface of side walls facing internal volume, of intermediate layer 3 containing from 50 to 100 wt % of silicon dioxide applied from top of substrate 25 and of surface layer 4 containing from 50 to 100 wt % of silicon nitride, to 50 wt % of silicon dioxide and to 20 wt % of silicon applied from top of intermediate layer 3. The crucible can include additional intermediate layer 31 on top of first intermediate layer 3 containing to 50 wt % of silicon nitride with residue containing silicon dioxide.
EFFECT: design of crucible eleiminating preparation of very thick coating on equipment of final user, also facilitation of easy and fast application of coating with improved anti-adhesion properties for production of silicon ingots without cracks.
11 cl, 2 dwg
FIELD: metallurgy, crystals.
SUBSTANCE: invention relates to control of the crystal growth process from the charge melt 6 in capsule 4 by method of axial heat current nearby solid-melt interface - by solid-melt -method. During the growing it is implemented the control of thermal behavior by means of regulators, connecting regulated variable with control variable. In the capacity of control variables there are used voltage at least at one of background heater sections and at one of sections immersed into the melt of solid-melt-method 2, in the capacity of measured regulated variables there are used temperatures of sections of background heater 1 TH1-TH4, temperatures T1, T2 in the bottom of solid-melt -method and bedplate of capsule T3-T5, defined by corresponding thermocouple, and in the capacity of non-measured regulated variables- temperatures of body bottom of solid-melt -method 8 Thot and capsule bedplate Tcold., which are, correspondingly, temperatures of hot solid-liquid boundary and cold crystal boundary, additionally regulatory control of the temperature is implemented at stage of capsule warming up only by thermopairs, located outside sections of background heater 1, from the beginning moment of charge melting- including and by thermopairs, which are in the capsule bedplate, and after full charge melting - also and by thermopairs in the bedplate of solid-melt heater, at that settings for corresponding temperatures T1 and T3 at stage of crystallisation is calculated before the beginning of crystallisation depending on required value of growth rate v. Invention provides required thermal behavior of crystallisation, optimal thermal conditions for crystal growing.
EFFECT: improvement of grown crystal.
15 cl, 1 dwg
FIELD: metallurgy, crystals.
SUBSTANCE: invention relates to growing from single crystals melt in temperature gradient with usage of heating element, immersed into molten zone. Facility contains growing vessel, furnace with combination background heater 11, capsule 4 on the basis 3, connected to the bottom rod 1, additional heater, immersed into melt inside the solid-melt interface(solid-melt heater) 7, connected to top rod 2, waterproof taken out from the chamber by means of withdrawal unit 10, thermocouple T1 and T2 in the body of solid-melt heater, T3 and T4 in support and T5-T8 nearby the section of background heater. Withdrawal unit 10 contains axis 9, fixedly connected to top rod 2, spring, connected to its bottom end with axis and implemented with the ability of pressure as the pressure increases in the chamber and movement lengthways the mentioned axis with the rod upwards, at that withdrawal unit 10 contains screwed on its body nut, restricting spring from the top side and indicated micrometre, rigid relative to body of withdrawal unit and indicating relocation bias of solid-melt heater inside the growing vessel lengthwise its axis before and during the crystallisation. Invention provides assure the control of melt temperature and to create optimal temperature field in growing crystal, including close to flat shape of solid-melt interface.
EFFECT: improvement of "А2Б6" compound semiconductor ensured by reduction of tensity in crystal and, as consequence, excluding fissuring, reduction of twinning and dislocation content in crystal, and also increasing of yield.
11 cl, 2 ex, 1 dwg
FIELD: metallurgy, crystals.
SUBSTANCE: invention relates to single crystal growing process from the melt in temperature gradient with usage of heating element, immersed into the molten zone. Facility for single crystal growing by method of axial heat current nearby solid-melt interface includes water-cooled chamber with bottom 1 and top 2 flanges, furnace with combination background heater 4 and building insulation 3, mold, consisting of capsule 5 with cover, immersed into heater capsule in hermetic enclosure - solid-melt heater 10, consisting of thermopair 11, and support 8 under the capsule 5, fixed on water-cooled rod 9 and consisting thermopairs 12, 14, facility for fixing of solid-melt heater in the top chamber flange, additionally background heater consists of at least of two sections I and II, allowing common withdrawal for voltage supplying, and solid-melt heater is located by height facility in the limit of top sections II higher the level, corresponding the location of mentioned common withdrawal in the chamber, for value h, equal to 5-30 mm depending on layer thickness of melt above the crystal, at which it is implemented crystallisation. Facility structure provides creation of axial temperature gradient in value wide range and high symmetry of thermal field. Implemented in growing crystal and in melt nearby it closed to one-dimensional temperature field, which provides, in essence, flat shape of solid-melt interface almost all over the section of crystal.
EFFECT: receiving of more peer single crystals with less amount of defects, connected to thermotension in single crystal during crystallisation and cooling-down, and increasing of yield.
17 cl, 6 dwg
FIELD: medicine, pharmaceutics.
SUBSTANCE: invention refers to using mixed metal compounds for preparing a drug preparation for neutralisation of gastric acid or buffer action thereon, as well as for treatment of a condition or a disease related to high gastric levels of acid. The mixed metal compound is a compound of formula (I): MII 1-aMIII aObAn- c.zH2O (I), wherein MII and MIII mean a two-valence and three-valence metal respectively, An- means an n-valence anion, 0.2≤a≤0.4, 0.2≤b≤1.5, 2+a is equal to 2b+Σcn, Σcn<0.9a, and z is equal to 2 or less. According to the invention, the mixed metal compound is presented in the form of a granulated material, wherein a diametre of 50 wt % of the granules makes 106 to 1180 mcm with the material comprising 50 wt % of the mixed metal compound, 3 to 12 wt % of noncovalent water and no more than 47 wt % of an excipient on granulated material weight basis. The mixed metal compound in the form of the granulated material represents a compound of formula (I) or a compound of formula (III): MII 1-xMIII x(OH)2An- y·mH2O (III) ; wherein MII and MIII mean a two-valence and three-valence metal respectively, An- means an n-valence anion, x=Σyn, 0<x≤0.4, 0<y≤1, and 0≤m≤10.
EFFECT: invention provides the buffer action on gastric acid, causing no effect of rebound acid hypersecretion.
46 cl, 3 tbl, 1 dwg
FIELD: medicine, pharmaceutics.
SUBSTANCE: invention can be applied in chemical industry, metallurgy and purification of industrial and domestic sewages. Extraction of iron with vegetable oils is realised from water solution with ratio water (W) to organic (O) phase W:O≥3 for Fe (III) and W:O= 3-6 for Fe(II); at pH 2-3 for Fe (III) and 9-11 for Fe (II) and Fe (III). Time of extraction for Fe (III) is 1-3 min and not more than 60 min for Fe (II).
EFFECT: method ensures high degree of efficiency of iron extraction from water solutions with simultaneous efficiency and safety of the process.
2 cl, 10 dwg, 3 tbl
SUBSTANCE: invention relates to chemistry. Aluminium salt solution is purified from iron by acidifying a mineral acid solution to concentration of 4.5-5.5 g-eq/dm3. The acidified solution is brought into contact with a granular cationite containing phosphonic acid functional groups. Iron is desorbed from the cationite with 3.5-5.3 M phosphoric acid solution. The steps for sorption and desorption of cationite are carried out in dynamic conditions.
EFFECT: invention increases the degree of purification of aluminium salts from iron and output of the purified salt per unit mass of the cationite.
3 cl, 3 tbl, 4 ex
SUBSTANCE: method of obtaining textured coatings with anisotropic coercitive force based on magnetic compounds involves synthesis of magnetic composite powders. To this end, strontium hexaferrite magnetic powder is uniformly placed in a channel on the surface of deformed metals and alloys and premoulding is performed. Milling is then carried out with a protective interlayer of titanium foil between the powder and mill rolls in a temperature interval from 20°C to 600°C, with subsequent annealing at temperature of 800-850°C or not less than 2.5 hours.
EFFECT: invention increases coercitive force and degree of anistropy thereof in magnetic coatings based on strontium hexaferrite.
SUBSTANCE: invention relates to a method of obtaining iron-carbon nanoparticles, characterised by that iron granules are treated with pulsed electric discharges in a reactor in octane or decane dispersion medium. Treatment is carried out with pulse energy of 0.5-1 J, voltage of 500 V, pulse frequency of 400 Hz, pulse duration of 15 mcm, discharge current of 250 A, and time for exposure to pulsed electric discharges is selected in the 50-120 s interval. The solid phase is separated from the obtained suspension by separate removal from the reactor of a suspension with a coarse fraction with particle size greater than 0.5-1.5 mcm and a suspension with a fine fraction with particle size 57-65 nm, from which a magnetic fraction is separated and then dried and heated to 150°C.
EFFECT: invention increases size homogeneity (particle size 57-70 nm), magnetic susceptibility and specific surface area of iron-carbon nanoparticles.
2 tbl, 1 dwg
SUBSTANCE: invention can be used in producing water-soluble materials, having current-conducting and magnetic properties, for further use as the base for ferromagnetic liquids. To obtain a water-soluble magnetically ordered adduct base on iron with substituted β-cyclodextrins, synthesis is carried out using aqueous solutions of iron (II) salts at pH 9-10 and room temperature in aerobic conditions and in the presence of substituted β-cyclodextrins (CD) in molar ratio Fe2+: NaH2PO2: CD=10:10:1 for 60 hours.
EFFECT: invention enables to obtain a water-soluble substance in form of a stable adduct in highly dispersed state, having magnetic properties under normal conditions without removal of oxygen from the system.
2 dwg, 4 ex