Synthesis of gallium oxide nanoparticles in supercritical water
SUBSTANCE: invention can be used in chemical industry. Gallium oxide Ga2O3 nanoparticles are obtained by mixing 0.1 M aqueous solution of Ga(NO3)3·8H2O with supercritical water. The reaction is carried out at temperature of 365-384°C and at pressure of 220-240 atm. The ratio of the volume of the gallium salt solution to the volume of supercritical water is preferably equal to 2:10.
EFFECT: synthesis of metal oxide nanoparticles and ecologically clean, wasteless technology.
2 cl, 1 ex, 2 dwg
The invention relates to the field of nano - and microparticles of metal oxides in supercritical water and can be used in obtaining materials and compounds of high purity and with unique properties.
For the synthesis of nanostructured materials, which are nanoparticles, nanofilms and nanowires proposed many methods that can be divided into two principal groups. First, obtain nanostructures of materials normal size, i.e. bulk materials. Second, obtaining nanostructures from molecular level.
Clean the oxides of various metals are widely used in practice. Many oxides, primarily Al2O3, W2O5, Cr2O3, Fe2O3and others, are used as catalysts for other hardening metals and to obtain ferrites.
The main methods of synthesis or a pure metal oxides are thermal decomposition of salts of (dry method) at high temperatures, and precipitation of hydroxides from solutions (wet method) with their subsequent calcination.
The main disadvantages of the known methods for the synthesis of metal oxides as follows:
1. Nitrates of alkali metals, used as starting substances during combustion pass into nitrites and oxides do not form.
2. Use what Libanius some salts are very difficult to obtain, for example, the oxides of strontium or barium, as their carbonates begin to decompose only at 1200-1300°C.
3. By annealing the salts are difficult to obtain pure metal oxides.
4. Salts formed of non-volatile acids (phosphates, borates, wolframite and others), when heated, do not decompose, with the exception of ammonium salts and mercury, and therefore cannot serve as source materials for the production of oxides of the respective metals.
5. By calcination of ammonium salts released ammonia-reducing agent, which can lead to contamination of the obtained product of the lower oxides of elements.
6. Since most of hydroxides (for the method of obtaining the metal oxides of hydroxides), deposited from solution, it is difficult to obtain in pure, free from impurities condition, it is difficult to get individual oxides in pure form as well.
7. Dehydration of hydroxides when annealing is not always going to end, and often the resulting oxides contain a small amount of hydroxide.
8. The purity and properties of metal oxides obtained by these methods are highly dependent on the mode and temperature of annealing.
Supercritical fluids are an attractive environment for the synthesis, modification and formation of nanoparticles of inorganic materials, in particular metal oxides (TiO2, Cr2O3, LiFePO4) Reverchon E., Adami R. Nanomaterials and supercritical fluids // J. of Supercritical Fluids. 2006. V.37. P.1; Jung J., Perrut M. Particle design using supercritical fluids: Literature and patent survey // J. of Supercritical Fluids. 2001. V.20. P.179; Zhang Y., Erkey C. Preparation of supported metallic nanoparticles using supercritical fluids: A review // J. of Supercritical Fluids. 2006. V.38. P.252; Aymonier C., Loppiner-Serani, A., H. Reveron, Y. Garrabos, F. Cansell Review of supercritical fluids in inorganic materials science // J. of Supercritical Fluids. 2006. V.38. P.242]. Such nanostructures and materials exhibit unusual properties that are different from those for bulk materials.
A known method for the synthesis of particles of metal oxides [T.Adschiri, Y.Hakuta, K.Arai, Hydrothermal synthesis of metal oxide fine particles at supercritical conditions, Ind. Eng. Chem. Res. 39 (2000) 4901; T.Adschiri, Y.Hakuta, K.Sue, K.Arai, Hydrothermal synthesis of metal oxide nanoparticles at supercritical conditions, J. Nanopart. Res. 3 (2001) 227; A.Cabanas, J.Darr, E.Lester, M.Poliakoff, Continuous hydrothermal synthesis of inorganic materials in a near-critical water flow reactor; the one-step synthesis of nano-particulate Ce1-xZrxO2(x=0-1) solid solutions, J. Mater. Chem. 11 (2001) 561], in which the hydrothermal synthesis of nano - and microparticles of metal oxides in supercritical water - ck-N2O.
A few basic single and multistage chemical reactions of precursor metal salts may be implemented in the synthesis of particles in SK-N2A: hydrolysis and dehydration, thermolysis, restore (as a rule, in the presence of hydrogen and oxidation. In the area of critical parameters of water increases its dissociation and, therefore, the concentration of H+and HE-/sup> . As a result, hydrothermal synthesis in SK-N2Of nanoparticles of oxides of metals from their salts are carried out in the two-stage reactions of hydrolysis and dehydration:
Hydrothermal method is simple in implementation and scaling is carried out in reactors, autoclaves or tubular flow reactors, allows you to control the properties and particle size.
There is a method of hydrothermal synthesis of particles of metal oxides, we adopted for the prototype [S.Kawasaki, Y.Xiuyi, K.Sue, Y.Hakuta, A.Suzuki, K.Arai. Continuous supercritical hydrothermal synthesis of controlled size and highly crystalline anatase TiO2nanoparticles. J. Supercritical Fluids 50(2009) 276-282], which carry out continuous synthesis of nanoparticles of titanium dioxide - TiO2in supercritical water in the presence of KOH.
To the main disadvantage of the prototype should include the application of the law for changing the solubility of the precursor materials. As a result of application of KOH in the reaction formed potassium sulfate K2SO4the removal of the reaction products require additional rinsing.
The invention solves the problem of efficient synthesis of compounds of metal oxides.
Method for obtaining nanoparticles of oxide, gallium Ga2O3who are shmesani the m 0.1M aqueous salt solution Ga(NO 3)3·8H2O with supercritical water in a volume ratio of 2:10 at the reaction temperature 365-384°C and the pressure 220-240 ATM.
The amount of gallium salt solution to the volume of supercritical water is, preferably, 2:10.
The technical result - the synthesis of compounds metal oxide-based nanoparticles, creating an environmentally friendly waste-free technology.
The original mother liquor for the synthesis of Ga2O3prepare by dissolving in water equimolar amount of salt Ga(NO3)3·8H2O. Hydrothermal synthesis of oxide is carried out in continuous mode in a flow type reactor, Figure 1.
The mother liquor from the tank 2 syringe pump 4 serves in a tubular reactor 5 by volume 7.2 cm3placed in the furnace with a fluidized bed of sand 7, the flow 1 through the mixer 6, which is mixed with the SK-N2Oh, the thread 2 is supplied Porshnev pump 3 from the container 1 in a continuous mode. Transformation is carried out at temperatures and pressures close to the critical parameters of the mixture containing more than 95% water, temperature 365-384°C, pressure 220-240 ATM. The products of the interaction of salts with SK-N2About out of the reactor to the heat exchanger 8 through the valve back pressure 9 the holding tank 10.
The products of hydrothermal synthesis, depending on the size and properties of the formed crystals, the ACCS are neoshadows mixture of particles in the water. The selection of the formed particles of oxides of metals from the solution for analysis of solid phase is carried out by centrifugation of the solution or by evaporation, followed by drying of the solid phase.
The structure, phase and elemental composition of the samples obtained compounds analyzed by the methods of scanning electron microscopy (HRTEM), x-ray phase analysis (XRD). In some cases, the formed water products analyzed using the method of UV spectroscopy.
Hydrothermal synthesis of Ga2O3carried out in continuous mode in the reactor flow type with the aforementioned method.
The invention is illustrated by the following example and illustrations.
Example 1. Synthesis of gallium oxide Ga2O3
For the synthesis of Ga2O3prepare 0.1M salt solution Ga(NO3)3·8H2About in the water. The reaction temperature 365-384°C, a pressure of 235 MPa. Volumetric flow rate of water - flow 2 is 10 ml/min, the flow rate of the reagent stream is 1-2 ml/min In the hydrothermal reaction products are formed in the form of a homogeneous solution of dark color, after evaporation which produces a solid phase. According to the results of HRTEM analyses of the synthesized compound is a crystal with a high dispersion: 2-5 nm. Figa, b. In separate blocks present pseudomorphic crystals (dimensions pseudomorphic is kristallov - to 100 nm).
The results of XRD analysis show that the main phase of the synthesized compounds is a compound Ga2O3together with a small amount of an unidentified crystalline phase.
The example and illustrations demonstrate that the proposed method and conditions of hydrothermal synthesis allow to synthesize gallium oxide nanoparticles of the desired size and properties.
As can be seen from the text and examples, the invention solves the problem of synthesis of metal oxide-based nanoparticles, creating an environmentally friendly waste-free technology.
1. Method for producing nanoparticles of oxide, gallium Ga2O3, characterized in that the obtaining nanoparticles of gallium oxide is performed by mixing 0.1 m aqueous solution of salt of gallium Ga(NO3)3·8H2About with supercritical water at the reaction temperature 365-384°C and the pressure 220-240 ATM.
2. The method according to claim 1, characterized in that the ratio of salt solution of gallium Ga(NO3)3·8H2About to supercritical water is preferably 2:10.
SUBSTANCE: invention relates to manganese- and zinc-doped indium antimonides which can be used in spintronics, where electron spin is used as an active element for storing and transmitting information, forming integrated and microfunctional circuits, as well as designing novel magneto-optoelectronic devices. A magnetic semiconductor material is disclosed, which contains indium, antimony, manganese and zinc, and is indium antimonide InSb doped with manganese in amount of 0.12-0.19 wt % Mn and zinc in amount of 0.71-1.12 wt % Zn, and has the formula InSb<Mn,Zn>.
EFFECT: invention enables to obtain material which is characterised by Curie point of 320 K and combines semiconductor and ferromagnetic properties.
2 dwg, 2 tbl, 3 ex
SUBSTANCE: invention relates to chemical technology for extracting inorganic materials. The method of activating aluminium involves immersing an aluminium sample into gallam in the melting temperature range of the gallam and/or aluminium in the presence of ultrasonic vibrations. The apparatus for activating aluminium has an ultrasonic radiator, an ultrasonic generator, an output current sensor for the generator, a comparator and a command device. The working face of the ultrasonic radiator is acoustically connected to the end surface of the aluminium sample. The excitation input of the radiator is connected through the current sensor to the output of the ultrasonic generator, and the output of the current sensor is connected through the comparator to the stop input of the command device, whose output is connected to the control input of the ultrasonic generator.
EFFECT: high output and quality of end products and high environmental safety of production.
6 cl, 3 dwg, 1 tbl, 3 ex
SUBSTANCE: invention can be used in production of materials which can protect from thermal radiation. The zinc oxide contains 0.25-25 wt % gallium and has charge carrier density ne equal to or greater than 2×1020/cm3 and charge carrier mobility µ ranging from 0.1 to 40 cm2/V-s. A thin film of the said gallium-containing zinc oxide has thickness equal to or less than 5 mcm, as well as degree of transmitting solar radiation Ts and degree of transmitting visible optical radiation Tv which satisfy the inequality Ts ≤ 1.4Tv-39. The thin film of gallium-containing zinc oxide satisfies the condition Y ≥ 0.4X+1.06 for film thickness equal to or greater than 400 nm and the condition Y ≥ 0.2X+0.98 for film thickness equal to or less than 300 nm, where X is charge carrier density of 10-20/ charge carrier mobility and Y equals Tv/Ts.
EFFECT: invention enables to obtain gallium-containing zinc oxide having thermal radiation protection properties while retaining high transparency for visible optical radiation.
22 cl, 10 dwg, 6 tbl
SUBSTANCE: magnetic semiconductor material is a compound of chromium, gallium and copper selenide having chemical formula CuGaCr2Se5 and characterised by Curie point of 318K.
EFFECT: invention enables to obtain material with Curie point higher than room temperature, having ferromagnetic and semiconductor properties.
1 dwg, 2 ex
SUBSTANCE: thallium metal, containing other elements, is dissolved in sulphuric acid with concentration of 90 to 100 g/l. The solution is evaporated, cooled and the residue is filtered. The obtained solution, which contains thallium sulphate, is filtered and evaporated. Hydrogen sulphide gas is passed through the solution and sulphides of heavy metals are precipitated. Thallium metal is separated by electrolysis. The obtained metal is dissolved in nitric acid and diluted with water to thallium concentration of 60 to 80 g/l. Potassium hydroxide is added until pH equals 10. Using electrolysis, thallium (III) oxide is deposited on the anode and thallium metal is deposited on the cathode. Current density at the anode ranges from 0.25 to 1.00 A/cm2, and from 0.05 to 3.00 A/cm2 at the cathode.
EFFECT: obtaining thallium oxide and thallium metal with low content of impurities maximum 0,0048%, high output of the desired product of minimum 84,2-99,6%, reduced formation of filtrates and pollution of the environment.
2 cl, 1 dwg, 10 ex
SUBSTANCE: molten gallium metal reacts with water in dispersion with supplying hydrogen peroxide concentrated 30 wt % and more at uniform velocity 200-250 ml/hour per kg of molten gallium within 3-6 hours till gallium oxidation. The reaction is one-stage in gallium to water ratio (0.8-1.0):(1.2-1.5). Produced gallium crystalline hydrate is dried and baked to make gallium oxide.
EFFECT: lower power inputs, simplified equipment and eliminated detrimental flows.
2 cl, 2 tbl, 2 ex
SUBSTANCE: present invention can be used in chemical industry. Ultrafine gallium oxide is obtained using self-propagating high-temperature synthesis method. Gallium oxide is mixed with metallic gallium, while adding gallium oxide powder to the mixture in ratio of 1: (0.136 - 0.148) : (0.047 - 0.059), respectively. Metallic gallium is oxidised through localised heating of the mixture in an oxygen-containing gas.
EFFECT: proposed invention allows for obtaining high quality gallium oxide with particle size less than 1 mcm and with output of the given fraction of not less than 85%, and less than 10-4% content of metallic gallium.
SUBSTANCE: reaction chamber is in form of two containers joined together. Chlorine in an airtight vessel and metallic gallium are put into the first container, and lithium nitride and ammonia in an airtight vessel are put into the second container. The chamber is then evacuated and sealed. The vessel containing chlorine is then opened and the first container is heated to 210-220°C. After that the vessel containing lithium nitride and ammonium is opened and the second container is heated to 850-870°C. The chamber is sealed again and the containers are separated. As a result the first container contains unneeded impurity substances, and the second contains solid gallium nitride.
EFFECT: obtaining pure gallium nitride and reduced pollution of the environment as a result of preventing substances used in the synthesis process from escaping.
1 dwg, 3 ex
FIELD: inorganic synthesis.
SUBSTANCE: invention is directed to preparation of gallium nitride powder that could be used as ceramics component when manufacturing semiconductor members of structures. Method of preparing ultrafine gallium nitride powder comprises combusting mixture of powdered gallium-containing compound with high-exothermic pulverized metal in a gas medium, said gallium-containing compound being liquid gallium metal or gallium oxide and said high-exothermic pulverized metal being aluminum, while, as gas medium for combustion, atmospheric air is used. Thus obtained ultrafine gallium nitride powder, in order to complete removal of impurities, is further subjected to chemical treatment in hydrochloric or sulfuric acid solutions followed by washing with distilled water.
EFFECT: simplified gallium nitride powder synthesis technology and enabled utilization of air as nitrogen-containing reagent.
1 tbl, 2 ex
FIELD: processes of nuclear physics.
SUBSTANCE: method comprises steps of creating beam of thallium atoms, for example by heating metallic thallium in evaporation chamber till 600 - 660°C; providing equilibrium pressure of thallium vapor 1 - 10 Pa; simultaneously igniting gas discharge in order to realize first stage of thallium atoms excitement to meta-stable state due to creating beam of thallium atoms in excited meta-stable state; then realizing second stage of excitement by means of laser irradiation during two successive steps. At first stage thallium atoms in excited meta-stable state are excited by means of laser irradiation, for example with wave length 535 nm to resonance state. At second stage atoms of desired thallium isotope in excited resonance state are transferred to Rydberg state by means of laser irradiation, for example with wave length 444 nm. At both stages of excitement pulse mode of laser irradiation with pulse duration, for example 5 - 10 s is used. After multi-stage excitement atoms of desired isotope of thallium are ionized and extracted from beam due to applying cross electric field at supplying pulse voltage in mode limiting occurring of super-irradiation from levels corresponding to Rydberg state. Preferably, voltage value is in range 10 - 25 kV, pulse duration is in range 30 - 100 ns. The whole process is realized in vacuum whose level provides creation of processes necessary for separation of thallium isotopes.
EFFECT: lowered power consumption, improved quality parameters of laser beam.
19 cl, 3 dwg, 10 ex
SUBSTANCE: method involves preparation of a suspension of nanodiamond powder and a liquid phase, adding the suspension to an electrolyte and conducting electrolysis to deposit a composite coating. The liquid phase used to prepare the suspension is ethyl alcohol or acetone, wherein the nanodiamond powder is added to the liquid phase in amount of 60-80 vol. %, and the powder in the suspension is dispersed by crushing and attrition grinding with a lap, after which the suspension is added to the electrolyte.
EFFECT: dispersing nanodiamond powder and endowing the powder with resistance to sedimentation and coagulation in the electrolyte.
SUBSTANCE: method includes electrolytic dissolution of at least one anode made of silicon into a melt of a mixture containing the following components, wt %: 0 ÷ 70 CsCl, 10 ÷ 60 KCl, 10 ÷ 45 NaCl, in an electrolytic cell under inert atmosphere, in the range of temperatures from 600 to 700°C at cathode density of current from 0.3 mA/cm2 to 100 mA/cm2 with release of alkaline metals on the cathode and recovery of silicon compounds in the melt volume.
EFFECT: production of electrolytic crystalline or X-ray amorphous silicon in the form of nano- and microstructural powders or fibres with high specific surface.
FIELD: process engineering.
SUBSTANCE: invention relates to powder metallurgy, particularly, to production of open-pore nano-structured metal. It may be used in data write and store systems, various magnetic systems, as carriers of various pharmaceutical preparations for directed transfer of medicines in magnetic fields, etc. Solution of iron sulphate and nickel chloride hexahydrate salts are heated to 80-90°C. Metals are deposited as iron and nickel hydroxides by adding sodium hydroxide to solution at continuous mixing of sodium hydroxide. Then, 20-30 ml of 65 wt %-hydrazine hydrate is added to the solution and held for 5-20 minutes.
EFFECT: single-fraction mono-dispersed powder with high content of metal phase.
3 cl, 2 dwg, 1 tbl, 17 ex
SUBSTANCE: device (50) for preparation of nanoparticles on a continuous basis comprises the first feeding device (1a) with the first feeding load (9) connected to the source (7) of the starting material, the first reactor (2) comprising the first heated reaction zone (13), the second reactor (3) comprising the second heated reaction zone (15), where all the said devices are connected to the channel of the material flow successively in the said order, at least one pressure control unit (18) mounted in the said channel of the material flow, a mixer (5) mounted in the said channel of the material flow between the first reactor (2) and the second reactor (3), the second feeding device (lb) with the second feeding pump (10) connected to the source (8) of the starting material, and the second feeding pump (10) is in liquid junction with the mixer (5), the control device (22) made with the ability to control the pressure value setting with the said pressure control unit (18) and/or the temperature value of the said heated reaction zones (13 and 15). The device is characterised in that after each heated reaction zone (13) in the channel of the material flow the appropriate cooling device (14, 16) is mounted for reducing the size of the nanoparticles in the process of their preparation, and the cooling devices (14, 16) are additionally made with the ability to cease this process of nanoparticles preparation. Also the invention relates to use of the device for preparation of nanoparticles/nanoemulsions/colloidal solutions.
EFFECT: invention enables to obtain nanoparticles which properties can be modified in the course of this process.
8 cl, 10 dwg
FIELD: medicine, pharmaceutics.
SUBSTANCE: invention refers to a powdered preparation for soft tissue regeneration with an antibacterial effect. The preparation contains 0.07-0.09 wt % of copper nanoparticles sized 30-40 nm, 0.03-0.05 wt % of zinc nanoparticles sized 30-70 nm, and low-molecular chitosan.
EFFECT: invention improves the effectiveness of wound healing, including in septic and infected ones, while simplifying the processes of preparing and using the preparation, and also prolonging a shelf life thereof.
2 cl, 3 ex
FIELD: measurement equipment.
SUBSTANCE: method is proposed to manufacture a vacuum sensor with a nanostructure, consisting in the fact that a thin-film semiconductor resistor is formed in the form of a meshy nanostructure (SiO2)50%(SnO2)50% by application of a sol of orthosilicic acid containing a stannum hydroxide, onto a silicon substrate with the help of a centrifuge and subsequent baking. The sol is prepared in two stages, at the first stage tetraetoxysilane and ethyl alcohol are mixed, then at the second stage distilled water is added to the produced solution, as well as hydrochloric acid (HCl) and stannum chloride dihydrate (SnCl2·2H2O). The vacuum sensor with the nanostructure made according to the proposed method comprises the body, the heterogeneous structure installed in it from thin films of materials, formed on the substrate of a semiconductor, the thin-film semiconductor resistor and contact sites to it, formed in the heterogenerous structure, leads of the body and contact conductors, which connect contact sites with body leads.
EFFECT: increased sensitivity of a vacuum sensor.
5 cl, 4 dwg
SUBSTANCE: metal strip contains a coating from carbon nanotubes and/or fullerenes soaked with metal chosen from the group consisting of Sn, Ni, Ag, Au, Pd, Cu, W or their alloys. Method for obtaining metal strip with the coating from carbon nanotubes and/or fullerenes and metal involves the following stages: a) application of diffusion barrier layer from transition metal Mo, Co, Fe/Ni, Cr, Ti, W or Ce onto a metal strip, b) application of a nucleation layer from metal salt containing metal chosen from the group Fe, the 9-th or the 10-th subgroup of the periodic table onto the diffusion barrier layer, c) introduction after stages a) and b) of treated metal strip to hydrocarbon atmosphere containing organic gaseous compounds, d) formation of carbon nanotubes and/or fullerenes on metal strip at temperature of 200°C to 1500°C, e) soaking of carbon nanotubes and/or fullerenes with metal chosen from the group containing Sn, Ni, Ag, Au, Pd, Cu, W or their alloys.
EFFECT: obtained metal strip with the coating has improved friction coefficient, increased transition resistance of a contact, increased resistance to friction corrosion, improved resistance to abrasion and increased ability to be deformed.
SUBSTANCE: invention can be used to make damping elements, shock absorbers, friction pairs and wear-resistant components of micromechanisms. Starting carbon material is placed in a working volume; nitrogen is pumped and removed until complete displacement of air. At the first step, nitrogen is pumped to working pressure of 220-250 MPa, heated to 1670-2020 K and held for not less than 1 minute. Temperature is then lowered to room temperature and pressure is lowered to atmospheric pressure. At the second step, the obtained carbon-nitrogen material is treated in a high-pressure apparatus at pressure of 7-15 GPa and temperature of 1620-1770 K for not less than 1 minute. Temperature is then lowered to room temperature and pressure is lowered to atmospheric pressure. The starting carbon material used is fullerites, for example C60 and/or C70, which are first ground to particle size smaller than 1 mcm in order to increase content of nitrogen in the finished material.
EFFECT: invention enables to obtain a compact carbon-nitrogen material with a bulbous structure, which contains 2,2-5,0 at % nitrogen, having Young's modulus of 43-67 GPa, microhardness of 5,4-8,2 GPa and hyperelastic recovery parameter of 92-97%.
3 cl, 5 dwg, 4 ex
FIELD: medicine, pharmaceutics.
SUBSTANCE: invention refers to a method for preparing stabiliser-coated nanocrystalline cerium dioxide characterised by antioxidant activity. The method involves preparing an aqueous solution of cerium salt and a stabiliser representing maltodextrin with a molar ratio of cerium to the stabiliser 1 to 1-4. Then, the prepared aqueous solution is added with drops of hydrous ammonia with stirring, and pH of the prepared solution is gradually increased to 7-8, maintained for 1-4 hours, the prepared colloidal solution of hydrous cerium nanoparticles is added with hydrous ammonia, and pH is increased to 11-12 and maintained for 1-10 hours to form a colloidal solution of cerium dioxide. Thereafter, an alcohol or ketone excess is removed and brought to the boiling point, while the formed precipitate of the non-aggregated nanoparticles of stabiliser-coated cerium dioxide, separated by decantation or filtration, washed 1-4 times in alcohol or ketone, and dried at temperature 50-80°C to constant weight. The prepared powder of the non-aggregated nanoparticles of stabiliser-coated cerium dioxide is re-dispersed in a polar solvent to form aggregation resistant sol.
EFFECT: invention provides preparing stabilised nanocrystalline cerium dioxide with a hydrodynamic diameter of 6-10 nm.
3 cl, 7 dwg, 4 ex
FIELD: electrical engineering.
SUBSTANCE: invention may be used for production of individual crystals of zinc oxide and arrays thereof for application as active elements, material for photocatalytic water treatment, piezoelectric sensors as well as for fundamental physical studies of crystal growth kinetics. Crystals are grown in the air using a continuous action ytterbium fibre laser with yellow metal surface with a layer of multi-walled carbon nanotubes applied thereon treated with such laser radiation with power density equal to approximately 105 W/cm2 during 10 sec. The method enables production of micro- and nanostructured zinc oxide arrays consisting of filamentary crystals, microplates and druses.
EFFECT: invention enables crystals production without special catalysts or crystallisation chambers.
SUBSTANCE: invention relates to a method of producing cerium dioxide nanoparticles and use thereof. Described is a method of producing cerium dioxide nanoparticles with a given lattice, which contain at least one transition metal (M), wherein: (a) an aqueous reaction mixture is prepared, said mixture containing a source of Ce3+ ions, a source of ions of one or more transition metals (M), a source of hydroxide ions, at least one nanoparticle stabiliser and an oxidant which oxidises the Ce3+ ion to a Ce4+ ion, at initial temperature ranging from about 20°C to about 95°C; (b) mechanical shearing of said mixture and passing said mixture through a perforated sieve to form a homogeneously distributed suspension of cerium hydroxide nanoparticles; and (c) creating temperature conditions that are effective for oxidation of the Ce3+ ion to a Ce4+ ion to form a product stream containing cerium dioxide nanoparticles, containing a transition metal Ce1-xMxO2, where x assumes a value from about 0.3 to about 0.8, said nanoparticles have a cubic fluorite structure, average hydrodynamic diameter ranging from about 1 nm to about 10 nm and geometric diameter from about 1 nm to about 4 nm, wherein the nanoparticle stabiliser is water-soluble and has a value Log KBC ranging from 1 to 14, where KBC denotes a constant for binding the nanoparticle stabiliser to a cerium ion in water and said temperature conditions that are effective for oxidation of the Ce3+ ion to a Ce4+ ion include temperature from about 50°C to about 100°C. Described is a method of preparing a homogeneous dispersion containing stabilised crystalline nanoparticles of cerium dioxide with a given lattice, containing a transition metal, Ce1-xMxO2, where M is at least one transition metal and x assumes a value from about 0.3 to about 0.8; (a) preparing an aqueous mixture which contains stabilised cerium dioxide nanoparticles containing a transition metal, Ce1-xMxO2, having a cubic fluorite structure, wherein, wherein said nanoparticles have average hydrodynamic diameter ranging from about 1 nm to about 10 nm and geometric diameter less than about 4 nm; (b) concentrating said aqueous mixture containing said stabilised cerium dioxide nanoparticles containing a transition metal, thereby forming an aqueous concentrate; (c) removing essentially all water from said aqueous concentrate to form an essentially water-free concentrate of stabilised cerium dioxide nanoparticles containing a transition metal; (d) adding an organic diluent to said essentially water-free concentrate to form an organic concentrate of said stabilised cerium dioxide nanoparticles containing a transition metal; and (e) merging said organic concentrate with a surfactant in the presence of a nonpolar medium to form said homogeneous dispersion containing stabilised crystalline nanoparticles of cerium dioxide containing a transition metal, Ce1-xMxO2, where M and x assume values given above. Described is a deposited coating for the catalytic converter of the exhaust system of an internal combustion engine, where said deposited coating is obtained using said homogeneous dispersion.
EFFECT: catalyst that is efficient for a reduction or oxidation reaction is described, where said catalyst is obtained using said homogeneous dispersion.
44 cl, 9 dwg, 2 tbl, 8 ex