Method of producing thermoelectric gas-sensitive material
SUBSTANCE: method includes forming a film with thickness of not more than 200 nm from semiconductor nanoparticles of SnO2 with size of not more than 50 nm. The film of SnO2 nanoparticles is then annealed at temperature of 330±20 K or 500±20 K for at least 15 min in an oxygen-containing atmosphere, followed by cooling to room temperature at a rate of at least 10 K/s.
EFFECT: broader functional capabilities of the material.
2 cl, 4 dwg
The invention relates to electronics, and is intended to create a material based on semiconductor nanoparticles or otherwise nanomaterial with gas thermoelectric effect, i.e. the magnitude of thermo-EMF of a nanomaterial can be sensitive to various gases into the external atmosphere. The invention can be used in thermoelectric devices that convert heat energy into electrical energy. Can also be used in various fields of science and technology for the development of gas sensors.
For the prototype selected nanomaterial-based nanocrystalline semiconductor films SnO2consisting of particles with a typical size of 10-100 nm . Such materials are widely used as gas sensitive layers of sensors and can be obtained by different methods of deposition (e.g., thermal, sputtering, ion-beam) followed by annealing or the Sol-gel method [1, 3]. The conductivity of such films depends strongly on the concentration of various detectable gases. It is known that an important role in the mechanism of sensitivity of such sensors to various detektivami gases plays chemisorption of oxygen, as detected gases, as a rule, actively interact with hammarbyhamnen on the surface of semiconductor particles with oxygen [1-3]. When is hemosorption molecules of oxygen, playing the role of the acceptor on the surface of semiconductor particles with a conductivity of n-type are formed negatively charged oxygen ions, and in the near-surface space charge region is formed depleted electrons charged layer and a corresponding bending of the energy bands near the surface . As a result, between the individual particles are formed of potential barriers and the conductivity of such a system can approximately be described by the following equation:
where Gv- the factor describing the bulk conductivity of the semiconductor, Vs- the height of the potential barrier. Increasing the height of the potential barriers Vsbetween nanoparticles during chemisorption of oxygen will lead to a reduction in conductivity. If chemisorption of oxygen occurs in a certain range of temperatures, at these temperatures the value of Vswill be maximum, and the temperature dependence of the conductivity will receive a minimum of [2, 3]. For thermopower S and the coefficient peltie P in a semiconductor is known to follow what her expression (up to a negligible here the constant term) :
or with the height of the potential barrier Vs:
where S is thermopower, S0- the energy difference between the bottom of the conduction band and the Fermi level at zero temperature, γ is the coefficient for the temperature dependence of the Fermi level position, Vssurface potential barrier between the nanoparticles. Thus, increasing the height of the potential barrier between the semiconductor nanoparticles, due to the increase in bending energy zones near their surface, can lead to increased thermoelectric properties of semiconductor nanomaterials. It is known that the efficiency of termoelectrica the fir materials is determined by the quality factor, equal to the product ZT. Here
where k is thermal conductivity [W/(MK)], σ is the electrical conductivity, S - thermo-EMF [V/K]. Currently the best value of the quality factor reaches ZT≈2 for some thermoelectric materials, for example, Bi2Te3, PbSe, but these materials have certain disadvantages - high working temperature, contain toxic, rare or expensive items [5-7]. As an alternative promising thermoelectric materials recently proposed oxides of metals, such as stable at high temperatures, more environmentally friendly and cheap. For example, available materials based on doped ZnO (ZT=0,47 at 1000 K) and layered cobalt oxide Ca3Co4O9(ZT=0,22 at 1000 K) [5, 8, 9]. In  proposed a material based on a mixture of tin oxide SnO2with the addition of ZnO and Ta2O5or Nb2O5. A powder mixture of oxides is then pressed into tablets, which are sintered at a temperature of from 1000 to 1400°C. the General formula of the obtained material can be written in the form of Sn1-x-yZnxMy 2where 0,76≤1-x-y≤0.99, and with inclusions of phase ZnSn2O4from 1 to 25 wt%. The particle size of the obtained polycrystalline porous material is in the range from 100 nm to 100 μm, and the preferred amount is from 5 to 70 micrometers. The disadvantage of this material is not sufficiently high values of thermo-EMF and the quality factor, which are 100-200 μv/K and 0.06 to 0.13, respectively, at 1000 K.
The technical result of the invention is
• functional enhancement of thermoelectric materials due to the possibility of changes in thermo-EMF of nanomaterial depending on the concentration of oxygen or other gases (H2, NH3, CO, CH4, NO2H2S) in the air;
• simplify and reduce the cost of thermoelectric material due to its production of nanoparticles SnO2without the use of toxic, rare or expensive materials such as lead, silver, bismuth, tellurium, or rare earth elements;
• increase thermo-EMF to 1.3 mV/K at the operating temperature of 330 K and up to 1.1 mV/K at the operating temperature of 500 K;
• increase the quality factor ZT of thermoelectric material to 1 at the operating temperature of 330 or 500 K.
To achieve the specified result, we propose a way to obtain
thermoelectric gatchev twitterlogo material, which is manufacturing film thickness of not more than 200 nm from the semiconductor nanoparticles SnO2with a size of not more than 50 nm, while after the production of the film of nanoparticles SnO2annealed at a temperature of 330±20 500±20 K for at least 15 minutes in an oxygen-containing atmosphere, followed by cooling to room temperature at a rate not less than 10 K/S.
This annealing is carried out in the air.
The figure 1 shows the temperature dependence of thermopower of the material.
The figure 2 shows the temperature dependence of the coefficient peltie, which reflects the temperature dependence of the Fermi level position according to equation (2).
The figure 3 shows the temperature dependence of the conductivity of the material.
The figure 4 shows the temperature dependence of the quality factor of the material.
The measurements were carried out on nanocrystalline film SnO2thickness of 200 nm, obtained by magnetron sputtering. The size of the individual nanoparticles in the obtained film are defined by electron microscope, was about 50 nm. Structurally experimental samples was paligorova substrate with dimensions of 5×to 0.5×0.2 mm, one side of which was the semiconductor film SnO2and on the other sputtered film of platinum, with Ujamaa heater. The heater was both resistance, the magnitude of which is controlled by the temperature of the sample. The sample temperature could be changed and stabilized at a predetermined value by using a specially designed electronic power supply unit with an accuracy of 0.1°C. To obtain a temperature gradient on the sample platinum heater was located only at one end of the sample. The temperature difference was measured using two thermocouples Au-Ni, placed at opposite ends of the sample. Differential thermo-EMF was measured in the temperature range of 300 to 550 K (Figure 1). The corresponding coefficient peltie, which reflects the temperature dependence of the Fermi level position according to equation (2)shown in figure 2. Figure 3 shows the temperature dependence of the conductivity. The obtained dependencies are clearly observed two extremum at temperatures of about 330 and 500 K or, respectively, 60 and 230°C. These extremes can be explained by the chemisorption of charged forms of oxygen O2-and O-at these temperatures. The maximum depth of the Fermi level in dependence on the temperature is determined by the change in height of the potential barrier at the chemisorption of oxygen and reaches around to 0.55 eV in the region of temperature of 500 K (Figure 2). If after heating to such temperature made the STI rapid cooling to room temperature at a rate not less than 10 K/s, increased the amount of the potential barrier remains as hammarbyhamnen oxygen molecules remain on the surface. Thus, thermo-EMF metal oxide semiconductor nanomaterials type SnO2, ZnO, can be substantially increased by the corresponding temperature material processing. Assessment of the quality factor ZT according to equation (4) based on the measured thermopower (Fig 1) and conductivity for the proposed nanomaterial (Figure 3) shows that its value reaches the value 1 when the two optimal temperatures of 330 and 500 K (Figure 4), which is comparable with the best thermoelectric materials. The value of the coefficient K for SnO2relied equal to 0.5 W/(m K) in the whole temperature range . Because of the strong phonon scattering at the boundaries of the particles, and various defects and impurities of the conductivity of polycrystalline porous materials can be much less than that of single crystals, therefore reducing the size of the nanoparticles and the film thickness can lead to a reduction in thermal conductivity . Thus, there is a possibility to further reduce thermal conductivity for the proposed nanomaterial and increase the quality factor ZT. Also in the proposed nanomaterial you can control and adjust the amount of potentialenergy between nanoparticles, to optimize the transport properties for maximum thermoelectric effect.
The resulting nanomaterial can be used in thermoelectric generators, as well as for the manufacture of various gas sensors to determine the content of oxygen or other gases (H2, NH3, CO, CH4, NO2H2S) in the air, and on the contacts of the gas sensor is generated EMF, which depends on the concentration of the detected gas.
1. S. Song, J. Cho, W. Choi et al, Sensors and Actuators 46 (1998) 42-19.
2. Morrison S.R. Chemical physics of solid surfaces. -M.: Mir, 1980. S.
3. A. Varfolomeev, A.V., Ariskin, V.V. Malyshev, ALEXANDER Razumov, S. Yakimov, Journal of analytical chemistry, vol 52, No. 1 (1997) p.66-68.
4. V.L. Bonch-Bruevich, YEAR Kalashnikov, Physics of semiconductors, -M.: Nauka, 1990.
5. MRS BULLETIN, vol.31, March 2006, p.193.
6. X.H. Ji, X.B. Zhao, Y.H. Zhang, B.H. Lu, H.L. Ni, J. Alloys Compd. 387 (2005) 282.
7. J. Seo, C. Lee, K. Park, J. Mater. Sci. 35 (2000) 1549
8. M. Ohtaki, T. Tsubota, K. Eguchi, H. Arai, J. Appl. Phys. 79 (1996) 1816.
9. Y. Zhang and J. Zhang, J. Of Materials and Processing technology, 208 (2008) 70-74.
10. Patent EP 2447233 A1, Tin oxide-based thermoelectric materials, 2012.
11. P.R. Bueno, J.A. Varela et al, J. American Ceram. Soc., 88 (9) (2005) 2629-2631
12. C. Poulier, D. Smith, J. Absi, Journal of the European Ceramic Society 27 (2007) 475-478.
1. Method for manufacturing thermoelectric gas sensitive material, which consists in the manufacture of film thickness h is more than 200 nm from the semiconductor nanoparticles SnO 2with a size of not more than 50 nm, wherein after the production of the film of nanoparticles SnO2annealed at a temperature of 330±20 500±20 K for at least 15 minutes in an oxygen-containing atmosphere, followed by cooling to room temperature at a rate not less than 10 K/S.
2. The method according to claim 1, characterized in that the annealing is carried out in air.
SUBSTANCE: method includes mechanical-activation processing in a planetary ball mill of solid solutions, which contain bismuth and antimony tellurides with an addition of a grinding agent and further sintering of obtained powders. Mechanical-activation processing is carried out successively in two stages: first, with centrifugal acceleration of grinding bodies in the interval from 800 to 1000 m/sec2 for 10-30 min, then with centrifugal acceleration of the grinding bodies in the interval from 20 to 100 m/sec2 for 20-40 min. As the grinding agent used are compounds of a layered structure, selected from the group: MoS2, MoSe, WS2, WSe, BN or graphite. The grinding agent is taken in an amount of 0.1-1.5 wt % of weight of the solid solution of bismuth and antimony tellurides. The obtained thermoelectric material consists of particles of the triple solid solutions of bismuth and antimony tellurides with a size from 5 nm to 100 nm, between which from 1 to 10 nm thick layers of a compound, selected from the group: MoS2, MoSe, WS2, WSe, BN or graphire, are located.
EFFECT: increase of the thermoelectric figure of merit.
2 cl, 3 dwg
SUBSTANCE: invention relates to thermoelectric generators. A thermoelectric generator (2) has multiple modules (1), each having a first end (3) and a second end (4) and which consist of an internal pipe (5) and an external pipe (6) and thermoelectric elements (7) in between. The modules (1) at their first end (3) or second end (4) are attached by their internal pipe (5) or external pipe (6) to an electrical conductor (9). The electrical conductor (9) is laminated and has a first end face (14) and a second end face (15), as well as a lateral surface (16). The first end face (14) is connected to the second end face (15) by multiple openings (17). Each opening is designed to attach one corresponding module (1). The electrical conductor (9) has electroconductive contacts (18) for electrical connection with contacts (8) of separate modules (1).
EFFECT: providing versatile or universal application in cars, including in existing types and models, providing reliable separation of fluid media and electrical contact.
8 cl, 15 dwg
SUBSTANCE: thermoelectric materials include polyaniline doped with various chemical additives. Manufacturing of a polymer material with p- and n-conductivity is carried out by means of the process of electric polymerisation from aqueous solution of aniline and hydrochloric acid with chemical additives.
EFFECT: increased efficiency of thermal energy conversion into electric one.
1 dwg, 1 tbl
SUBSTANCE: invention relates to the field of thermal electricity. The invention concept is as follows: insulating substrate (12) is equipped with the first (18) and second (20) junction areas. At the substrate (12) there is the first formed assembly of conductor or semiconductor elements (14) passing in parallel and in the first direction from the first (18) junction area up to the second (20) one. At the other side of the substrate (12) there is the second assembly of or semiconductor elements (22) insulated electrically from the first assembly and passing in the direction opposite from the first direction, from the first junction area (18) up to the second (20) one. In the junction areas (18, 20) the electrical connecting elements (24) connect the elements (14) and (22) of the first and second assemblies. Two elements (14, 22) of the same assembly are separated in preset direction at the preset average distance (d1, d2) in the junction areas (18, 20). The average size (P) of the connecting elements (24) in the preset direction is bigger than a maximum value of average distances (d1, d2) between elements of the same assembly. The distance (E) in the preset direction between edges of two connecting elements (24) is less than minimum values of average distances (d1, d2) between elements of the same assembly.
EFFECT: simplifying the construction and improving reliability.
6 cl, 6 dwg
SUBSTANCE: as a material for a thermoelement used is a polymer material - polyaniline, doped with various chemical additives. Production of the polymer material with p- and n- conductivity is realised by a process of electropolymerisation from a water solution of aniline and hydrochloric acid with chemical additives.
EFFECT: increase of productivity coefficient.
SUBSTANCE: invention refers to thermoelectric devices. The invention concept is as follows: the method includes manufacturing of rods of thermoelectric material by hot extrusion. Thereafter lateral side of rods is treated. Water paint compound with fluorine rubber is applied to the rod lateral sides by means of cathodic or anodic electrodeposition in order to obtain a protective polymer coating. Then the rods are washed and cured thermally. The rods are cut in order to obtain semiconductor paths of the preset length. Antidiffusion metal coating is applied to butt ends of the obtained semiconductor paths so that the edge touches the protective polymer coating without crossing it. The single- or multi-cascade thermoelectric module contains semiconductor paths of N- and P-conductivity so that they are located in parallel and do not tough each other. Semiconductor paths of N- and P-conductivity are manufactured as per the method specified above.
EFFECT: improving chemical, thermal and mechanical resistivity, providing high adhesion and elasticity for polymer coating of thermoelectric paths.
9 cl, 11 dwg
SUBSTANCE: rods of thermoelectric material based on solid solutions of Bi2Te3-Bi2Se with n-type conductivity, effectiveness ZT>1.2 and mechanical strength of not less than 150 MPa are made through mechanical activation synthesis of a ternary solid solution of Bi2Te2.85Se0.15 with n-type conductivity from starting components. The donor alloy used is Bi11Sei2Cl9. The obtained material then undergoes preliminary cold pressing into a briquette and hot extrusion under pressure through a draw plate in two steps. First, the briquette enters the conical part of the draw plate at pressure of 250-350 MPa, where it undergoes plastic deformation at temperature of 350-420°C with elongation ratio of 8-11. At the same pressure, the formed rod enters the equal channel part of the draw plate, where it undergoes further plastic deformation by equal channel multi-angular pressing with deformation ratio ε<1 at temperature which is 50-70°C higher than temperature in the conical part of the draw plate. The thermoelectric rod then undergoes post-extrusion annealing at temperature of 300-350°C for 1-5 days.
EFFECT: improved method.
2 cl, 2 tbl, 1 dwg
SUBSTANCE: monocrystalline films of a solid bismuth-antimony solution are obtained using zonal recrystallisation of vacuum sputtered, uniform-composition polycrystalline films of a solid bismuth-antimony solution under a protective coating, the melting point of which is higher than that of the obtained film, at a higher rate of zone movement than when growing bulk monocrystals (for films of solid bismuth-antimony solutions higher than 1 cm/h versus 0.05 mm/h for bulk crystals).
EFFECT: invention enables to obtain monocrystalline films of a solid bismuth-antimony solution with uniform volume distribution of components.
FIELD: electrical engineering.
SUBSTANCE: thermoelectric element has thermocouples containing an n-type semiconductor and a p-type semiconductor. The both semiconductors are welded on to an electrically connective contact material. The thermocouples -type semiconductor and a p-type semiconductor are welded on to the contact material in the course of separate welding processes. One simultaneously welds on all the n-type semiconductors on one side of the thermoelectric element and/or all p-type semiconductors on one side of the thermoelectric element.
EFFECT: enhanced reliability of the semiconductors connection to the contact material.
41 cl, 12 dwg
SUBSTANCE: nanocomposite thermoelectric material comprises thermoelectric nanocrystals and alloying fullerene molecules distributed among them. Concentration of charge carriers is controlled by concentration of introduced alloying fullerene molecules that take electrons from nanocrystals of the thermoelectric and are quantum traps for electrons. The volume concentration of alloying fullerene molecules Kalloy, which are added into the nanocomposite thermoelectric, is defined by the difference of Knanocomposite and Kinitial, divided into the average number k of electrons taken from nanocrystals per one alloying fullerene molecule, namely; Kalloy=(Knanocomposite-Kinitial)/k.
EFFECT: modification of electric properties of materials due to variation of electric charge carrier concentration in nanocomposites.
3 cl, 2 tbl, 2 dwg
SUBSTANCE: invention can be used in making catalyst supports, sorbents, electrochemical catalysts and lithium-ion batteries. The method includes reacting, at 700-900°C, a calcium salt, e.g., calcium tartrate or calcium tartrate doped with a transition metal, which is a template precursor, and liquid or gaseous carbon-containing compounds or mixtures thereof as a carbon source. The obtained product is treated with hydrochloric acid. Concentration of the doped transition metal is not more than 1 at%.
EFFECT: obtaining a homogeneous mesoporous carbon material characterised by specific surface area of 850-930 m2/g, pore volume of 2,9-3,3 cm3/g and average pore diameter of 10-30 nm.
4 cl, 3 dwg, 9 ex
SUBSTANCE: invention relates to nanotechnology. The graphene structures in the form of flat carbon particles with the surface of up to 5 mm2 are obtained by burning in air atmosphere or inert gas of composite press material produced from micro- and nanodisperse powders of active metals such as aluminium, titanium, zirconium, nanodisperse powders of silicon or aluminium borides taken in an amount of 10-35 wt %, and fluoropolymers such as polytetrafluoroethylene or a copolymer of tetrafluoroethylene and vinylidene fluoride, taken in amount of 90-65 wt %.
EFFECT: increased yield of graphene.
3 tbl, 4 dwg, 5 ex
SUBSTANCE: method for synthesis of hollow nanoparticles of γ-Al2O3 is carried out in two steps, the first step including plasma-arc synthesis of an aluminium-carbon material, which includes evacuating a vacuum chamber, filling said chamber with an inert gas, igniting direct-current arc between a graphite electrode and a metal-carbon composite electrode and spraying the composite electrode, which is in the form of a graphite rod with a cavity in which aluminium wire is inserted with weight ratio C:Al of 15:1, and the second step including annealing the synthesized material in an oxygen-containing medium at atmospheric pressure and temperature of 400-950°C for one hour.
EFFECT: obtaining nanodispersed aluminium oxide power, the particles of which are hollow spheres with diameter of 6-14 nm, which is suitable for use in catalytic applications and material science.
2 cl, 5 dwg
SUBSTANCE: immunoadjuvant is claimed representing hydroxyapatite nanoparticles with adsorbed synthetic peptide - CXCR ligand of 1 2 and receptors. The vaccine against influenza is presented, comprising the claimed immunoadjuvant and chimeric protein NS-ESAT. FIELD: On inorganic nanoparticles the adsorbed peptide Pro-Pro-Gly-Pro-His (PPGPH) which represents the ligand of CXCR 1 and 2. The base of solving the problem set was obtaining complexes of hydroxyapatite nanoparticles with the chimeric protein NS-ESAT. The protocols of obtaining these complexes are developed, as well as the effectiveness of their generation was quantitatively studied. As the results of tests of the complexes obtained on laboratory animals the data is obtained giving evidence that these complexes are capable to stimulate a cellular link of immune response more effectively than the commercial adjuvant. On this account the resulting complexes may be considered as a potential vaccine component, particularly anti-influenza, particularly against such highly pathogenic strains of influenza virus as H5N1, H1N1, and others. As a result of the studies carried out the affinity of hydroxyapatite nanoparticles to chimeric protein NS-ESAT-6 is revealed. A fragment of the influenza virus NS1 protein (125 amino acid residues long) having high affinity for phosphate groups, provides an increased affinity of the fusion protein to hydroxyapatite nanoparticles. The immunological adjuvant is proposed to use as nanoparticles of hydroxyapatite, which, according to the results of tests on laboratory animals is able to stimulate more effectively than the commercial adjuvant the cellular link of immune response. In addition, the use of the sorption properties of hydroxyapatite is proposed for creation of nanocompositions comprising individual immunomodulators stimulating the immune response to the target antigens.
EFFECT: increased immunogenicity of vaccines with use of inorganic nanoparticles.
3 cl, 4 dwg
SUBSTANCE: equichannel angular pressing of a cylindrical workpiece is performed. Ultra-fine structure with the grain size of 200-300 mcm is formed in the workpiece metal. Then the workpiece is cut into disks with each of them being subject to intensive plastic deformation by torsion with the help of two rotating strikers. Deformation of torsion is carried out under the room temperature and the pressure of 4-6 GPa with the number of strikers' revolutions n≤2. Therewith the homogeneous nanocrystalline structure with the grain size of ≤100 mcm is formed.
EFFECT: improved physical and mechanical properties of the material being processed.
2 cl, 1 tbl, 1 ex
SUBSTANCE: invention relates to means for protection against electromagnetic fields of electrotechnical and electronic devices and biological objects and can be applied for creation of electromagnetic screens and echo-free chambers. Composite material for protection against electromagnetic radiation consists of polymer base with distributed in it particles of alloy of system Fe-Cu-Nb-Si-B, and is characterised by the fact that it represents multi-layered construction, each layer of which is made of said composition, and content of alloy particles in each layer constitutes 70-90 wt % and is limited by certain range of size of particles from continuous line 1-200 mcm with increase of particle dimensions in each following layer.
EFFECT: increase of working range of material frequencies from 100 MHz to 10 GHz with preservation of low values of reflection coefficient and high values of magnetic permeability.
3 cl, 1 tbl, 2 dwg, 2 ex
SUBSTANCE: invention is directed at obtaining functionalised carbon nanotubes having good compatibility with polymeric matrices. The carbon nanotubes are subjected to processing in hydrogen peroxide vapour at a temperature of from 80°C to 160°C for 1-100 hours. The processing may be carried out in a unit with fluidised bed of the carbon nanomaterial.
EFFECT: method is characterised by high efficiency, lack of toxic oxidation products, low consumption of reagents, can be easily scaled.
2 cl, 2 dwg, 4 tbl, 4 ex
SUBSTANCE: invention relates to nano-component energy supplement in the liquid hydrocarbon fuel in the form of metal nanoparticles, at that the metal nanoparticles are used as non-oxidised aluminium nanoparticles not larger than 25 nm coated with anti-oxidant protector. Also the liquid hydrocarbon fuel is described, containing the said non-oxidised aluminium nanoparticles not larger than 25 nm coated with anti-oxidant protector, and the stabiliser.
EFFECT: improving the efficiency of fuel combustion with the use of non-oxidised aluminium nanoparticles as energy supplement in liquid hydrocarbon fuel.
4 cl, 1 dwg, 1 ex
SUBSTANCE: method of producing saturated carboxylic acids of general formula
includes hydrogenation of unsaturated carboxylic acids with hydrazine hydrate in the presence of a nickel catalyst while heating in aqueous sodium hydroxide solution for 3-4 hours. The unsaturated carboxylic acids to be hydrogenated are selected from: methacrylic acid, norbornene carboxylic acid and trans-cinnamic acid; the catalyst used is nickel nanoparticles obtained by reducing nickel (II) chloride hexahydrate with hydrazine hydrate in an aqueous alkaline medium in situ, and the process is carried out in molar ratio NaOH: unsaturated carboxylic acid of 1.3-1.5:1 at 60°C.
EFFECT: simple method of producing compounds of the disclosed structural formula.
SUBSTANCE: invention relates to a method of producing a methanation process catalyst, which includes impregnating a support based on active aluminium oxide in the form of granules in a solution containing nickel nitrate, followed by drying at temperature of 100°C-120°C and calcining the impregnated support at temperature of 450°C-500°C, wherein a modification additive - an organic acid with concentration of 0.5-20.0 wt % - is added to the nickel nitrate solution, and the finished catalyst contains NiO monocrystallites with mean sampling size in the range of 2-3 nm, with concentration of NiO of 12.0-25.0 wt % and γ-Al2O3 - the balance.
EFFECT: high reliability and activity, low cost and faster implementation of the method.
3 cl, 1 tbl, 13 ex
FIELD: carbon materials.
SUBSTANCE: weighed quantity of diamonds with average particle size 4 nm are placed into press mold and compacted into tablet. Tablet is then placed into vacuum chamber as target. The latter is evacuated and after introduction of cushion gas, target is cooled to -100оС and kept until its mass increases by a factor of 2-4. Direct voltage is then applied to electrodes of vacuum chamber and target is exposed to pulse laser emission with power providing heating of particles not higher than 900оС. Atomized target material form microfibers between electrodes. In order to reduce fragility of microfibers, vapors of nonionic-type polymer, e.g. polyvinyl alcohol, polyvinylbutyral or polyacrylamide, are added into chamber to pressure 10-2 to 10-4 gauge atm immediately after laser irradiation. Resulting microfibers have diamond structure and content of non-diamond phase therein does not exceed 6.22%.
EFFECT: increased proportion of diamond structure in product and increased its storage stability.