WO2010144070A2 - Method to produce nanoparticles of metal-oxygen system of the specified composition by electron beam evaporation and condensation in vacuum - Google Patents
Method to produce nanoparticles of metal-oxygen system of the specified composition by electron beam evaporation and condensation in vacuum Download PDFInfo
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- WO2010144070A2 WO2010144070A2 PCT/UA2010/000027 UA2010000027W WO2010144070A2 WO 2010144070 A2 WO2010144070 A2 WO 2010144070A2 UA 2010000027 W UA2010000027 W UA 2010000027W WO 2010144070 A2 WO2010144070 A2 WO 2010144070A2
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- Prior art keywords
- oxygen
- nanoparticles
- condensate
- vacuum
- carrier material
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- 239000002105 nanoparticle Substances 0.000 title claims abstract description 74
- 239000001301 oxygen Substances 0.000 title claims abstract description 69
- 229910052760 oxygen Inorganic materials 0.000 title claims abstract description 69
- 238000000034 method Methods 0.000 title claims abstract description 60
- 238000009833 condensation Methods 0.000 title claims abstract description 43
- 230000005494 condensation Effects 0.000 title claims abstract description 43
- 238000005566 electron beam evaporation Methods 0.000 title claims abstract description 13
- 239000000203 mixture Substances 0.000 title claims description 52
- 239000012876 carrier material Substances 0.000 claims abstract description 34
- 239000000758 substrate Substances 0.000 claims abstract description 34
- 239000000463 material Substances 0.000 claims abstract description 32
- 238000001704 evaporation Methods 0.000 claims abstract description 26
- 230000008020 evaporation Effects 0.000 claims abstract description 26
- 229910052751 metal Inorganic materials 0.000 claims abstract description 24
- 239000002184 metal Substances 0.000 claims abstract description 24
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 22
- 238000010438 heat treatment Methods 0.000 claims abstract description 19
- 239000007788 liquid Substances 0.000 claims abstract description 18
- 239000007787 solid Substances 0.000 claims abstract description 14
- 230000008021 deposition Effects 0.000 claims abstract description 13
- 238000002156 mixing Methods 0.000 claims abstract description 6
- 238000000354 decomposition reaction Methods 0.000 claims abstract description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 48
- 239000000126 substance Substances 0.000 claims description 23
- 230000008569 process Effects 0.000 claims description 19
- 239000007789 gas Substances 0.000 claims description 15
- 230000008859 change Effects 0.000 claims description 11
- 239000000084 colloidal system Substances 0.000 claims description 10
- 239000000956 alloy Substances 0.000 claims description 9
- 229910045601 alloy Inorganic materials 0.000 claims description 9
- 238000002844 melting Methods 0.000 claims description 9
- 230000003993 interaction Effects 0.000 claims description 8
- 230000008018 melting Effects 0.000 claims description 8
- 238000001816 cooling Methods 0.000 claims description 6
- 239000004094 surface-active agent Substances 0.000 claims description 6
- 238000007669 thermal treatment Methods 0.000 claims description 6
- 230000005855 radiation Effects 0.000 claims description 5
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims description 3
- 239000011734 sodium Substances 0.000 claims description 3
- 229910052708 sodium Inorganic materials 0.000 claims description 3
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 2
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 2
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 claims description 2
- 239000011575 calcium Substances 0.000 claims description 2
- 229910052791 calcium Inorganic materials 0.000 claims description 2
- 239000000919 ceramic Substances 0.000 claims description 2
- 238000000227 grinding Methods 0.000 claims description 2
- 239000011777 magnesium Substances 0.000 claims description 2
- 229910052749 magnesium Inorganic materials 0.000 claims description 2
- 239000011591 potassium Substances 0.000 claims description 2
- 229910052700 potassium Inorganic materials 0.000 claims description 2
- 229910052810 boron oxide Inorganic materials 0.000 claims 1
- 150000001805 chlorine compounds Chemical class 0.000 claims 1
- JKWMSGQKBLHBQQ-UHFFFAOYSA-N diboron trioxide Chemical compound O=BOB=O JKWMSGQKBLHBQQ-UHFFFAOYSA-N 0.000 claims 1
- NVIFVTYDZMXWGX-UHFFFAOYSA-N sodium metaborate Chemical compound [Na+].[O-]B=O NVIFVTYDZMXWGX-UHFFFAOYSA-N 0.000 claims 1
- 239000002086 nanomaterial Substances 0.000 abstract description 3
- 238000003786 synthesis reaction Methods 0.000 abstract description 3
- 229910010272 inorganic material Inorganic materials 0.000 abstract description 2
- 239000011147 inorganic material Substances 0.000 abstract description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 26
- 239000002245 particle Substances 0.000 description 22
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 19
- 150000002739 metals Chemical class 0.000 description 15
- 238000010894 electron beam technology Methods 0.000 description 14
- 239000011780 sodium chloride Substances 0.000 description 12
- 239000010949 copper Substances 0.000 description 11
- 238000000137 annealing Methods 0.000 description 10
- SZVJSHCCFOBDDC-UHFFFAOYSA-N ferrosoferric oxide Chemical compound O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 10
- 238000000151 deposition Methods 0.000 description 9
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 8
- 239000011858 nanopowder Substances 0.000 description 8
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 7
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 7
- 239000012298 atmosphere Substances 0.000 description 7
- 150000001875 compounds Chemical class 0.000 description 7
- 229910052802 copper Inorganic materials 0.000 description 7
- 229910052742 iron Inorganic materials 0.000 description 7
- 239000010936 titanium Substances 0.000 description 7
- 238000004519 manufacturing process Methods 0.000 description 6
- 230000003647 oxidation Effects 0.000 description 6
- 238000007254 oxidation reaction Methods 0.000 description 6
- 150000003839 salts Chemical class 0.000 description 6
- 239000010408 film Substances 0.000 description 5
- 239000011148 porous material Substances 0.000 description 5
- 239000003381 stabilizer Substances 0.000 description 5
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 4
- BERDEBHAJNAUOM-UHFFFAOYSA-N copper(I) oxide Inorganic materials [Cu]O[Cu] BERDEBHAJNAUOM-UHFFFAOYSA-N 0.000 description 4
- KRFJLUBVMFXRPN-UHFFFAOYSA-N cuprous oxide Chemical compound [O-2].[Cu+].[Cu+] KRFJLUBVMFXRPN-UHFFFAOYSA-N 0.000 description 4
- 238000003795 desorption Methods 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- 238000012916 structural analysis Methods 0.000 description 4
- 229910052719 titanium Inorganic materials 0.000 description 4
- QPLDLSVMHZLSFG-UHFFFAOYSA-N Copper oxide Chemical compound [Cu]=O QPLDLSVMHZLSFG-UHFFFAOYSA-N 0.000 description 3
- 238000003776 cleavage reaction Methods 0.000 description 3
- 238000004090 dissolution Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000000605 extraction Methods 0.000 description 3
- 230000006872 improvement Effects 0.000 description 3
- 239000011553 magnetic fluid Substances 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 230000007017 scission Effects 0.000 description 3
- 229910000108 silver(I,III) oxide Inorganic materials 0.000 description 3
- 238000001179 sorption measurement Methods 0.000 description 3
- 230000006641 stabilisation Effects 0.000 description 3
- 238000011105 stabilization Methods 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 125000004429 atom Chemical group 0.000 description 2
- 238000005100 correlation spectroscopy Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 239000003814 drug Substances 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 2
- 230000005291 magnetic effect Effects 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 229910052709 silver Inorganic materials 0.000 description 2
- 239000004332 silver Substances 0.000 description 2
- 238000004627 transmission electron microscopy Methods 0.000 description 2
- 238000011282 treatment Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- FOIXSVOLVBLSDH-UHFFFAOYSA-N Silver ion Chemical compound [Ag+] FOIXSVOLVBLSDH-UHFFFAOYSA-N 0.000 description 1
- 229910010252 TiO3 Inorganic materials 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 239000012300 argon atmosphere Substances 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 150000003841 chloride salts Chemical class 0.000 description 1
- 230000015271 coagulation Effects 0.000 description 1
- 238000005345 coagulation Methods 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000005137 deposition process Methods 0.000 description 1
- 238000010494 dissociation reaction Methods 0.000 description 1
- 230000005593 dissociations Effects 0.000 description 1
- 238000001493 electron microscopy Methods 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 230000005294 ferromagnetic effect Effects 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 238000001883 metal evaporation Methods 0.000 description 1
- 239000002082 metal nanoparticle Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 239000002923 metal particle Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- GNRSAWUEBMWBQH-UHFFFAOYSA-N nickel(II) oxide Inorganic materials [Ni]=O GNRSAWUEBMWBQH-UHFFFAOYSA-N 0.000 description 1
- 125000004430 oxygen atom Chemical group O* 0.000 description 1
- 238000005289 physical deposition Methods 0.000 description 1
- 238000005240 physical vapour deposition Methods 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 239000003870 refractory metal Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000002207 thermal evaporation Methods 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 238000007738 vacuum evaporation Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B13/00—Oxygen; Ozone; Oxides or hydroxides in general
- C01B13/14—Methods for preparing oxides or hydroxides in general
- C01B13/20—Methods for preparing oxides or hydroxides in general by oxidation of elements in the gaseous state; by oxidation or hydrolysis of compounds in the gaseous state
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G23/00—Compounds of titanium
- C01G23/04—Oxides; Hydroxides
- C01G23/047—Titanium dioxide
- C01G23/07—Producing by vapour phase processes, e.g. halide oxidation
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G3/00—Compounds of copper
- C01G3/02—Oxides; Hydroxides
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G49/00—Compounds of iron
- C01G49/02—Oxides; Hydroxides
- C01G49/08—Ferroso-ferric oxide [Fe3O4]
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G5/00—Compounds of silver
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2002/00—Crystal-structural characteristics
- C01P2002/80—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70
- C01P2002/88—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70 by thermal analysis data, e.g. TGA, DTA, DSC
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/01—Particle morphology depicted by an image
- C01P2004/03—Particle morphology depicted by an image obtained by SEM
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/51—Particles with a specific particle size distribution
- C01P2004/52—Particles with a specific particle size distribution highly monodisperse size distribution
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer
Definitions
- the invention pertains to the field of new nanomaterial synthesis in vacuum and producing nanodispersed powders and colloid systems, and can be applied in medicine, chemical technology, micro- and nanoelectronics and instrument- making.
- PVD vapour phase
- Method of producing ultrafine oxide powders by electron beam evaporation of initial substances can be an example of a method to produce metal oxide nanoparticles [J.D.Ramsay, R.G.Avery. Ultrafine oxide powder prepared by electron beam evaporation. Part 1 Evaporation and condensation process. Journal of materials science, 9, 1974, 1681-1688].
- This method allows deposition of nanoparticles on the internal nickel-plated surface of a copper water-cooled tube from a sample of the initial material, which is placed into a rotating crucible and heated by the electron beam through a slot in the tube. Pressure and type of gas fed into the chamber, are used to control the structure of the produced nanopowders, which are then scraped off the surface of nickel-plated copper water-cooled tube.
- Such a method was used to produce nanoparticles of oxides of different metals of the size of ⁇ 10 nm which were then added to the carrier liquid.
- Liquid film saturated with particles was replaced by fresh film due to chamber revolution, which resulted in a continuous increase of particle concentration in the liquid.
- chamber rotation velocity of 2 revolutions per minute and pressure of 0.03 Pa in it the intensity of metal evaporation reached 0.3 g/min.
- Application of this process of producing magnetic fluid allowed making rather small particles of such metals as iron, cobalt and nickel.
- a disadvantage of the above method of producing colloid systems and of the magnetic fluid proper produced by this method is a rather low effectiveness of fixing the nanoparticle size due to their 1 stabilization by surfactants in a thin film, because of absence of convective flows in the fluid and thorough coverage of the particle by the surfactant, which results in a cumbersome procedure of subsequent treatment of the colloid to produce such small particles, because the latter can be annealed in argon atmosphere, and then the flocculated particles are separated by centrifuging and again dispersed in the fluid in the presence of a stabilizer.
- the method inefficient and unsuitable for large-scale manufacturing of colloid systems, because it is difficult to deal with a large liquid surface in vacuum.
- this invention pertains to single-stage method to produce nanopowders of metals or alloys on their base, as well as chemical compounds of these metals, encapsulated into a salt shell by evaporation of the initial material and salt in a closed volume and simultaneous condensation of their vapour phases on a metal substrate.
- this invention specially envisages substrate preheating.
- Such a solution addresses the problem of manufacturing nanopowders of metals, alloys or certain chemical compounds, encapsulated into a dense inert shell, which ensures their protection from oxidation in the atmosphere and their easy extraction through shell dissolution.
- such a solution prevents a change of material chemical composition because of chemical interaction of atoms present in the material composition with gases present in the chamber atmosphere.
- this invention cannot be used to manufacture in a single stage the encapsulated into salt shell nanopowders of chemical compounds of many metals with oxygen because of a low heat of formation of these chemical compounds.
- such chemical compounds as Ag 2 O, AgO, Cu 2 O, CuO, NiO have such a low heat of formation (6 - 60 ccal/mole) that at heating and evaporation by the electron beam they decompose, with metal condensing on the substrate, and oxygen being removed by vacuum pumps. That is, when trying to produce nanopowders of the above chemical compounds by the above method, we will have in the dense salt shell a nanopowder of pure metal, and not the chemical compound that evaporates.
- the primary object of this invention is creation of a highly-efficient method to produce nanoparticles of metal-oxygen system of the specified composition by evaporation and condensation in vacuum, in which, owing to the proposed changes in the technology of its implementation, formation and change of the composition of initial material nanoparticles are provided in one process, owing to the possibility of physico-chemical interaction of their open surface with oxygen, with is fed into the vacuum chamber / condensation zone, i.e. capability of single-stage production of nanoparticles of metal-oxygen system of the specified composition is provided.
- the defined object is achieved by proposing a method to produce nanoparticles of metal-oxygen system of the specified composition by electron beam evaporation and condensation in vacuum, which includes simultaneous heating and evaporation in the vacuum chamber of solid initial material and solid carrier material from at least two separate vessels, mixing of vapour flows of initial material and carrier, deposition in the condensation zone of mixed vapour flow on a substrate with fixing of initial material nanoparticles on the substrate by carrier material, which solidifies, and formation of nanoparticle condensate in the carrier, in which, according to the invention, an initial material is selected from a group, which includes metals and their alloys (Me), carrier material is selected from soluble in liquid and evaporable in vacuum without decomposition simple and complex inorganic substances, selected from a group which includes chlorides of sodium, potassium, calcium, magnesium, oxide of boron, metaborate of sodium and their mixtures, substrate temperature is set and maintained by dosed cooling in the range of formation of open micro- and nanosized porous structure of carrier material below 0.5 of its melting temperature
- Such a solution allows elimination of direct radiation heating of carrier material at heating in a closed vessel by any source of energy, particularly carrier material with low melting temperature, that prevents its spattering, and provides a better directed flow of carrier vapour through the outlet of the above vessel. It is rational to perform ionization of initial material vapour flow. Such a solution allows acceleration of the vapour flow and improvement of nanoparticle condensation conditions in open pores of the carrier.
- Such a solution allows performing additional treatment of metal-oxygen condensate through temperature increase, adjustment of composition of the atmosphere and time of additional high-temperature chemico-thermal treatment. It is rational to realize the process so that nanoparticle concentration in the above condensate was in the range from 0.1 to 30 vol.%.
- Such a solution allows improvement of process efficiency, adjustment of nanoparticle size, and at the same time prevention of significant growth of nanoparticle sizes through formation of their large aggregates and complexes. It is rational to further include grinding and mixing of the above-mentioned produced condensate.
- Such a solution greatly simplifies the process of nanoparticle extraction from the carrier, because the nanoparticles fixed in the solid carrier can be stored for any length of time without violation of their composition or their size, and the stabilization process is performed at the final stage at condensate dissolution and preparation of colloid system of nanoparticles.
- Fig. 1 illustrates the schematic of electron beam unit for realization of the process to produce nanoparticles of metal-oxygen system by evaporation and condensation in vacuum.
- Fig. 2 illustrates an example of porous NaCl nanostructure at Ag deposition.
- Fig. 3 illustrates the distribution of dimensions of Ag nanoparticles in a colloid system produced by laser correlation spectroscopy.
- Fig. 4 illustrates the change of mass of NaCl-Ag condensate during heating and cooling of the sample in air.
- Fig. 5 illustrates the change of mass of NaCl-Cu condensate during heating and cooling of the sample in air.
- Fig. 6 illustrates the change of mass of KCl-Fe condensate during heating and cooling of the sample in air.
- Fig. 7 illustrates the change of mass of NaCl-Ti condensate during heating and cooling of the sample in air.
- a vacuum chamber of electron beam unit (Fig. 1 ).
- Compacted rod 2 of initial inorganic material is placed into cylindrical water-cooled crucible 1
- rod 4 of solid carrier material soluble in liquid is placed into adjacent crucible 3.
- Vacuum of the order of 10 "4 Torr (mm Hg) is created in the chamber.
- Surfaces of both the rods are heated by electron beam guns 5 and 6 to melting, which results in formation of mixed vapour flow 7 of initial material and carrier, which is deposited on water-cooled substrate 8.
- Porous structure of carrier material 4 with open pores is produced at condensation by setting and maintaining temperature of substrate 8 in the range of formation of micro- and nanosized porous structure of carrier material 4 with open pores and below melting temperature of carrier material 4 through control of temperature and flow rate of cooling water.
- a condensate of nanoparticles of initial material 2, having an open surface is produced in the micro- and nanosized porous structure of carrier material 4 with open pores.
- power of electron beam guns 5 and 6 is cut off, and the process of evaporation and condensation is completed.
- Condensate chemical composition determined in scanning electron microscope CamScan with X-ray attachment INCA-200 Energy was on the level of: Ag - 28.72 wt.% (9.55 at.%); O 2 - 2.83 wt.% (6.35 at.%); NaCl being the balance. Ratio of atomic percent of O 2 and Ag is equal to 0.7, allowing the condensate composition to be conditionally presented as
- Fig. 2 shows the characteristic columnar porous structure of the section
- FIG. 3 shows the distribution of dimensions of Ag nanoparticles in water with addition of a surfactant (nanoparticle stabilizer), obtained by laser correlation spectroscopy.
- the other phase is X-ray amorphous. Electronograms of thin cleavages of the condensate obtained by transmission electron microscopy in HITACHI H-800 instrument, show presence of NaCl and low-intensity diffraction rings of Ag crystalline lattice.
- Fig. 4 shows the dependence of relative change of condensate mass on temperature, derived using thermogravimetric analyzer "TGA-7". Note the minimum in the curve at the temperature of 220 - 250° C, which corresponds to Ag 2 O composition. Appearance of a minimum is indicative of a successive development of two processes at condensate heating: desorption of initially sorbed oxygen atoms by silver nanoparticles (physical adsorption) and subsequent chemical adsorption with further removal of gaseous dissociation products.
- Condensate composition was as follows: copper - 25.3 wt.% (12.9 at.%), oxygen - 4.34 wt.% (8.8 at.%), NaCl being the balance.
- Ratio of atomic percent of oxygen and copper is equal to 0.68, allowing condensate composition to be conditionally presented as CuOo .68 - X-ray structural analysis reveals NaCl and Cu 2 O phases. Average size of Cu 2 O particles in water solution with stabilizer addition is equal to 27 nm.
- Oxygen desorption (relative mass loss) at condensate heating at the rate of 10° C/min in air is shown in Fig. 5.
- Adsorbed oxygen content in the condensates decreases with increase of condensation temperature up to 150 - 200° C.
- Condensate composition was as follows: Fe - 20.1 wt.% (10.5 at.%); O 2 - 13.3 wt.% (24.0 at.%); KCl being the balance. Ratio of atomic percent of oxygen and iron is equal to 2.29, allowing condensate composition to be conditionally presented at FeO 2 29 or Fe 2 O 4 58 .
- X-ray structural analysis registers diffraction which is inherent only to KCl. Electron microscopy analysis of thin cleavages of the condensate revealed blurred diffraction rings of Fe 3 O 4 . Average size of particles of this phase is equal to 3 - 4 nm.
- Thermogravimetric curve of these sample which describes oxygen desorption is given in Fig. 6.
- Lowering of oxygen content is over at approximately 550° C, reaching the value of 5.6 wt.% (10.08 at.%), i.e. 13.9 at.% of oxygen and initial iron content of 10.5 at.% remain in the condensate.
- Isothermal annealing of initial condensates in air at 200° C for 1 hour increases the average size of Fe 3 O 4 particles up to 5 - 6 nm.
- Fe 2 O 3 phase also appears in addition to KCl and Fe 3 O 4 phases.
- Average size of particles is 5 — 7 run, but larger particles of 30 - 40 nm are also found.
- Annealing at 650° C for 10 min fixes KCl, Fe 3 O 4 and Fe 2 O 3 phases. Average particle size increases to 8 - 12 nm, and large particles increase to 20 - 60 nm. Example 4.
- Condensate composition was as follows: titanium - 14.9 wt.% (8.3 at.%), oxygen - 18.1 wt.% (30.2 at.%), NaCl being the balance. Ratio of atomic percent of oxygen and titanium is equal to 3.6, allowing the condensate composition to be conditionally presented as TiO 3 6 .
- X-ray structural analysis registers only NaCl structure. Transmission electron microscopy analysis of thin cleavages of the condensate revealed also fine Ti particles. Average size of particles is 2 - 3 nm.
- Oxygen desorption at condensate annealing in air is shown in Fig. 7. Lowering of oxygen content is over approximately at 650° C, reaching about 7.0 wt.% (11.7 at.%) at initial oxygen content of 30.2 at.%. Thus, 18.5 at.% of oxygen and initial titanium content of 8.3 at.% remain in the condensate, i.e. it corresponds to TiO 2 2 composition.
- Isothermal annealing of initial condensate in air at 200° C is accompanied by appearance of TiO 2 phase (rutile). At annealing at 400° C anatase appears in addition to NaCl and rutile phases. In the presence of fine fraction of particles, a larger fraction of up to 20-30 nm is found in individual zones. At annealing at 650° C, clear diffraction rings of polycrystalline structure of anatase are registered alongside titanium, and the coarser particle fraction increases up to dimensions of 30 - 70 nm.
- condensation of nanoparticles in a solid porous environment allows a more precise fixation and preservation of their size, and producing nanoparticles with a high- oxygen-to-metal ratio, where oxygen is at the stage of physical and chemical adsorption.
- Further heat treatment allows removing the remaining physically adsorbed oxygen and forming new phase systems.
- change of substrate temperature and temperature of further heat treatment allows adjustment and selection of the composition and size of the produced nanoparticles.
- the claimed method to produce nanoparticles of metal-oxygen system of a specified composition by electron beam evaporation and condensation in vacuum allows realizing it by simple techniques in the currently available equipment for electron beam evaporation of metals and alloys and does not requires additional highly expensive devices.
- the claimed method of producing nanoparticles of metal-oxygen system by electron beam evaporation and condensation in vacuum and nanopowders and colloid systems produced by this method are needed in medicine, ecology, food industry, chemical technology, micro- and nanoelectronics.
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Abstract
The invention pertains to synthesis of new nanomaterials in vacuum. A method to produce nanoparticles of metal -oxygen system by electron beam evaporation and condensation in vacuum is proposed, which includes simultaneous heating and evaporation of solid initial material and solid carrier material from at least two separate vessels in the vacuum chamber, mixing of vapour flows of initial material and carrier, deposition of mixed vapour flow on the substrate in the condensation zone with fixing of initial material nanoparticles on the substrate by carrier material which solidifies, and formation of nanoparticle condensate in the carrier. Used as the carrier material fixing the nanoparticles is a solid, soluble in liquid and evaporable in vacuum without decomposition simple or complex inorganic material.
Description
Method to produce nanoparticles of metal-oxygen system of the specified composition by electron beam evaporation and condensation in vacuum
Technical field The invention pertains to the field of new nanomaterial synthesis in vacuum and producing nanodispersed powders and colloid systems, and can be applied in medicine, chemical technology, micro- and nanoelectronics and instrument- making.
Prior art Known are methods to produce highly-dispersed powders by vacuum condensation of metal vapours on substrates, which are heated up to certain temperatures, where the conditions of interaction of metal atoms and molecules with the surface have the main role in nanoparticle formation. These are the methods of physical deposition from the vapour phase (PVD). Method of producing ultrafine oxide powders by electron beam evaporation of initial substances can be an example of a method to produce metal oxide nanoparticles [J.D.Ramsay, R.G.Avery. Ultrafine oxide powder prepared by electron beam evaporation. Part 1 Evaporation and condensation process. Journal of materials science, 9, 1974, 1681-1688]. This method allows deposition of nanoparticles on the internal nickel-plated surface of a copper water-cooled tube from a sample of the initial material, which is placed into a rotating crucible and heated by the electron beam through a slot in the tube. Pressure and type of gas fed into the chamber, are used to control the structure of the produced nanopowders, which are then scraped off the surface of nickel-plated copper water-cooled tube. Such a method was used to produce nanoparticles of oxides of different metals of the size of < 10 nm which were then added to the carrier liquid.
With such a method of producing oxide nanoparticles, however, a certain aggregation of them occurs at film condensation on the substrate, which requires a considerable lowering of the substrate temperature, as well as additional operations for further dispersion of the condensate. In addition, such a manufacturing method
does not allow producing nanoparticles of discrete dimensions, as in this case large platelike conglomerates form even at thorough subsequent dispersion of the condensate. Therefore, discrete nanoparticles should be produced by condensation of their vapour flows directly in a disperse environment with simultaneous stabilization. The main feature of this process consists in that both the stages have to be combined in time, so as to avoid particle cohesion under the action of attractive forces.
From publications by Kimoto K., Kamiya Y., Nonoyama M., Uyeda R. // An Electron Microscope Study on Fine Metal Particles Prepared by Evaporation in Argon Gas at Low Pressure. // Jpn. J. Appl. Phys., 1963, V.2, P. 702-704; Nakataki L, Furubayashi T., Takanashi T., Hanaoka H. // Preparation and magnetic properties of colloidal ferromagnetic metals. // J. Mag. Mat., 1987, V.65, #283, P.261-264 known is the method to produce colloid systems (magnetic fluids), which contain nanoparticles of magnetic metals, by electron beam evaporation of metals and condensation in vacuum in a disperse environment, where the method of vacuum evaporation of metals is combined with their condensation in liquid. The vapour source was placed into the center of vacuum chamber, which was a rotating horizontal cylinder. A solution of surfactant (stabilizer) in a hydrocarbon liquid with low pressure of saturated vapours was placed on the cylinder bottom. At cylinder revolution a thin liquid film formed on its wall, in which metal vapour condensation occurred. Stabilizer present in the solution made the particle surface liophylic, thus markedly limiting their growth. Liquid film saturated with particles, was replaced by fresh film due to chamber revolution, which resulted in a continuous increase of particle concentration in the liquid. At chamber rotation velocity of 2 revolutions per minute and pressure of 0.03 Pa in it, the intensity of metal evaporation reached 0.3 g/min. Application of this process of producing magnetic fluid allowed making rather small particles of such metals as iron, cobalt and nickel.
A disadvantage of the above method of producing colloid systems and of the magnetic fluid proper produced by this method, is a rather low effectiveness of
fixing the nanoparticle size due to their1 stabilization by surfactants in a thin film, because of absence of convective flows in the fluid and thorough coverage of the particle by the surfactant, which results in a cumbersome procedure of subsequent treatment of the colloid to produce such small particles, because the latter can be annealed in argon atmosphere, and then the flocculated particles are separated by centrifuging and again dispersed in the fluid in the presence of a stabilizer. In addition, in its current form the method is inefficient and unsuitable for large-scale manufacturing of colloid systems, because it is difficult to deal with a large liquid surface in vacuum. It is also difficult to place in a horizontal rotating tube a sufficiently large vapour source with electron beam heating, and, on the other hand, a considerable increase of the melt surface area may promote evaporation or solidification of the molten film of liquid due to a high flow of radiant energy from the heated surface of the melt.
The closest by the totality of features to the claimed invention and selected as the closest analog is the described in Patent of Ukraine #82448 of 10.04.2008, Ustinov A.I., et al., method to produce nanopowders by evaporation and condensation in vacuum, which includes simultaneous heating and evaporation of solid initial material and solid carrier material from at least two separate vessels, mixing of vapour flows of the initial material and carrier, deposition of mixed vapour flow on the substrate with fixing of initial material nanoparticles on the substrate by the carrier material, which solidifies, and formation of nanoparticle condensate in the carrier. More specifically, this invention pertains to single-stage method to produce nanopowders of metals or alloys on their base, as well as chemical compounds of these metals, encapsulated into a salt shell by evaporation of the initial material and salt in a closed volume and simultaneous condensation of their vapour phases on a metal substrate.
To promote formation of a more dense (without porosity) structure of condensed salt, which would protect initial material nanoparticles from oxidation in the vacuum chamber atmosphere, as well as in air atmosphere, this invention specially envisages substrate preheating.
Such a solution addresses the problem of manufacturing nanopowders of metals, alloys or certain chemical compounds, encapsulated into a dense inert shell, which ensures their protection from oxidation in the atmosphere and their easy extraction through shell dissolution. At the same time, such a solution prevents a change of material chemical composition because of chemical interaction of atoms present in the material composition with gases present in the chamber atmosphere. This means that this invention cannot be used to manufacture in a single stage the encapsulated into salt shell nanopowders of chemical compounds of many metals with oxygen because of a low heat of formation of these chemical compounds. For instance, such chemical compounds as Ag2O, AgO, Cu2O, CuO, NiO have such a low heat of formation (6 - 60 ccal/mole) that at heating and evaporation by the electron beam they decompose, with metal condensing on the substrate, and oxygen being removed by vacuum pumps. That is, when trying to produce nanopowders of the above chemical compounds by the above method, we will have in the dense salt shell a nanopowder of pure metal, and not the chemical compound that evaporates.
In addition, the above preheating of the substrate and formation of a dense
(without porosity) structure of condensed salt, which tightly protects metal nanoparticles from oxidation both in the vacuum chamber atmosphere and in the air atmosphere, limits the minimum dimensions of the produced nanoparticles, and simultaneously makes it impossible to further improve the composition, structure and shape of nanoparticles by chemico-thermal treatment after condensate production.
Essence of invention The primary object of this invention is creation of a highly-efficient method to produce nanoparticles of metal-oxygen system of the specified composition by evaporation and condensation in vacuum, in which, owing to the proposed changes in the technology of its implementation, formation and change of the composition of initial material nanoparticles are provided in one process, owing to the possibility of physico-chemical interaction of their open surface with oxygen, with
is fed into the vacuum chamber / condensation zone, i.e. capability of single-stage production of nanoparticles of metal-oxygen system of the specified composition is provided.
The defined object is achieved by proposing a method to produce nanoparticles of metal-oxygen system of the specified composition by electron beam evaporation and condensation in vacuum, which includes simultaneous heating and evaporation in the vacuum chamber of solid initial material and solid carrier material from at least two separate vessels, mixing of vapour flows of initial material and carrier, deposition in the condensation zone of mixed vapour flow on a substrate with fixing of initial material nanoparticles on the substrate by carrier material, which solidifies, and formation of nanoparticle condensate in the carrier, in which, according to the invention, an initial material is selected from a group, which includes metals and their alloys (Me), carrier material is selected from soluble in liquid and evaporable in vacuum without decomposition simple and complex inorganic substances, selected from a group which includes chlorides of sodium, potassium, calcium, magnesium, oxide of boron, metaborate of sodium and their mixtures, substrate temperature is set and maintained by dosed cooling in the range of formation of open micro- and nanosized porous structure of carrier material below 0.5 of its melting temperature ( K) to create open micro- and nanosized porous structure of carrier material on the substrate and produce in the open micro- and nanosized porous structure of carrier material a condensate of nanoparticles, which have an open surface, dosed feed of oxygen / oxygen- containing gases, vapours and their mixtures into the vacuum chamber / condensation zone is performed, in order to change the nanoparticle composition through physico-chemical interaction of open surface of initial material nanoparticles with oxygen, and to produce nanoparticles of metal-oxygen system of specified composition. Further chemico-thermal treatment of the produced condensate in air or other oxygen-containing gases, vapours and their mixtures can also be performed.
Such a solution allows simultaneous evaporation of any metals (alloys) and inorganic carrier substances, porous condensate of which will form on the substrate an efficient system of physico-chemical nanoreactors, capable of fine adjustment of the composition, shape, dimensions and structure of nanoparticles of metal- oxygen system, using deposition process parameters, such as substrate temperature, condensation rate, feeding oxygen / oxygen-containing gases, vapours and their mixtures into the vacuum chamber / condensation zone, ionization of vapour flow of metals (alloys) and other, as well as subsequent chemical-thermal treatments of condensates separated from the substrate. Therefore, such a solution allows implementation of the process of synthesis of nanoparticles of metal- oxygen system of the specified composition. Ability of solid water-soluble and evaporable in vacuum inorganic substances and their mixtures used as carrier material fixing the nanoparticles, to dissolve in liquid greatly simplifies the process of their extraction from the carrier. It is rational to heat the initial material by laser radiation.
Such a solution allows evaporation of any refractory metals and their alloys.
It is rational to apply radiation heating and evaporation from ceramic crucibles.
Such a solution allows evaporation of any low-melting metals and their alloys.
It is rational to perform dosed evaporation of carrier material by variation of physical surface area of carrier material placed into an open vessel.
Such a solution allows additional dosing of carrier vapour flow.
It is also rational to perform dosed evaporation of carrier material placed into a closed vessel (reactor), through this vessel outlet.
Such a solution allows elimination of direct radiation heating of carrier material at heating in a closed vessel by any source of energy, particularly carrier material with low melting temperature, that prevents its spattering, and provides a better directed flow of carrier vapour through the outlet of the above vessel. It is rational to perform ionization of initial material vapour flow.
Such a solution allows acceleration of the vapour flow and improvement of nanoparticle condensation conditions in open pores of the carrier.
It is rational to perform dosed feed of oxygen / oxygen-containing gases, vapours and their mixtures into the vacuum chamber / condensation zone after the process or during condensate deposition on the substrate.
Such solutions allow simultaneous physico-chemical interaction of open surface of forming nanoparticles with oxygen, which is fed into the vacuum chamber /condensation zone.
It is rational to perform additional high-temperature chemico-thermal treatment of metal-oxygen condensate in oxygen / oxygen-containing gases, vapours and their mixtures.
Such a solution allows performing additional treatment of metal-oxygen condensate through temperature increase, adjustment of composition of the atmosphere and time of additional high-temperature chemico-thermal treatment. It is rational to realize the process so that nanoparticle concentration in the above condensate was in the range from 0.1 to 30 vol.%.
Such a solution allows improvement of process efficiency, adjustment of nanoparticle size, and at the same time prevention of significant growth of nanoparticle sizes through formation of their large aggregates and complexes. It is rational to further include grinding and mixing of the above-mentioned produced condensate.
Such a solution allows improvement of homogeneity of the produced condensate composition.
It is rational to extract the nanoparticles from the above condensate by its dissolution in at least one liquid and stabilize them by a surfactant dissolved in the above liquid, producing a colloid system of nanoparticles.
Such a solution greatly simplifies the process of nanoparticle extraction from the carrier, because the nanoparticles fixed in the solid carrier can be stored for any length of time without violation of their composition or their size, and the
stabilization process is performed at the final stage at condensate dissolution and preparation of colloid system of nanoparticles.
Brief description of drawings / figures.
Technical essence of the claimed invention is clarified below by a detailed description and specific examples with references to the appended drawings/figures, in which:
Fig. 1 illustrates the schematic of electron beam unit for realization of the process to produce nanoparticles of metal-oxygen system by evaporation and condensation in vacuum. Fig. 2 illustrates an example of porous NaCl nanostructure at Ag deposition.
Fig. 3 illustrates the distribution of dimensions of Ag nanoparticles in a colloid system produced by laser correlation spectroscopy.
Fig. 4 illustrates the change of mass of NaCl-Ag condensate during heating and cooling of the sample in air. Fig. 5 illustrates the change of mass of NaCl-Cu condensate during heating and cooling of the sample in air.
Fig. 6 illustrates the change of mass of KCl-Fe condensate during heating and cooling of the sample in air.
Fig. 7 illustrates the change of mass of NaCl-Ti condensate during heating and cooling of the sample in air.
Detailed description of the invention
Method to produce nanoparticles of metal-oxygen system by electron beam evaporation and condensation in vacuum is realized in a vacuum chamber of electron beam unit (Fig. 1 ). Compacted rod 2 of initial inorganic material is placed into cylindrical water-cooled crucible 1, rod 4 of solid carrier material soluble in liquid is placed into adjacent crucible 3. Vacuum of the order of 10"4 Torr (mm Hg) is created in the chamber. Surfaces of both the rods are heated by electron beam guns 5 and 6 to melting, which results in formation of mixed vapour flow 7 of initial material and carrier, which is deposited on water-cooled substrate 8. Porous structure of carrier material 4 with open pores is produced at condensation by
setting and maintaining temperature of substrate 8 in the range of formation of micro- and nanosized porous structure of carrier material 4 with open pores and below melting temperature of carrier material 4 through control of temperature and flow rate of cooling water. As a result, a condensate of nanoparticles of initial material 2, having an open surface, is produced in the micro- and nanosized porous structure of carrier material 4 with open pores. After a certain operation time, power of electron beam guns 5 and 6 is cut off, and the process of evaporation and condensation is completed. After completion of the process, dosed feed of oxygen or oxygen-containing gases, vapours and their mixtures (air) into the vacuum chamber / condensation zone is performed, and thus, chemical composition of nanoparticles already fixed in the porous structure of carrier material 4 with open pores is changed due to physico-chemical interaction of their open surface with oxygen or oxygen-containing gases, vapours and their mixtures (air). As a result, a condensate of nanoparticles of metal-oxygen system of initial material 2 of specified composition and size, fixed in solid carrier 4, is produced on the substrate. This condensate can be stored for a long time without coagulation of1 nanoparticles.
If feeding of oxygen / oxygen-containing gases, vapours and their mixtures in small doses into vacuum chamber/ condensation zone is performed during deposition of a mixed vapour flow on a substrate, thereby chemical composition of nanoparticles of initial material 2 is partially changed due to physico-chemical interaction of their surface with oxygen, and nanoparticles of metal-oxygen system are produced already during their formation and fixing in the porous structure of carrier material 4. Example 1
Method to produce silver-based nanoparticles was performed by the electron beam from two adjacent copper water-cooled crucibles of 50 mm diameter. Compacted Ag rod 2 of 48.5 mm diameter and 60 mm height was placed into cylindrical water-cooled crucible 1 (Fig. 1), and NaCl 4 was placed into adjacent crucible 3. Surface of both the rods was heated by electron beam guns 5 and 6 up
to melting. Mixed vapour flow 7 was deposited on flat iron substrate 8 at temperature of 40 ± 10° C at the rate of 8 - 10 μm/min. Vacuum in the working chamber remained on the level of 10"4 Torr (mm Hg) during deposition. After 6 min of operation power of electron beam guns 5 and 6 was cut off and the process was completed. Condensate thickness was approximately 50 μm.
After deposition, at the moment of loss of vacuum in the chamber, the condensate came into contact with air. Condensate chemical composition determined in scanning electron microscope CamScan with X-ray attachment INCA-200 Energy was on the level of: Ag - 28.72 wt.% (9.55 at.%); O2 - 2.83 wt.% (6.35 at.%); NaCl being the balance. Ratio of atomic percent of O2 and Ag is equal to 0.7, allowing the condensate composition to be conditionally presented as
Agθo.7.
Fig. 2 shows the characteristic columnar porous structure of the section
(fracture) of the condensate obtained in scanning electron microscope CamScan. Fig. 3 shows the distribution of dimensions of Ag nanoparticles in water with addition of a surfactant (nanoparticle stabilizer), obtained by laser correlation spectroscopy.
X-ray structural analysis of the condensates records only NaCl structure.
The other phase is X-ray amorphous. Electronograms of thin cleavages of the condensate obtained by transmission electron microscopy in HITACHI H-800 instrument, show presence of NaCl and low-intensity diffraction rings of Ag crystalline lattice.
Unbalanced chemical composition of the considered condensates is demonstrated by annealing in air at the rate of 10° C/min. Fig. 4 shows the dependence of relative change of condensate mass on temperature, derived using thermogravimetric analyzer "TGA-7". Note the minimum in the curve at the temperature of 220 - 250° C, which corresponds to Ag2O composition. Appearance of a minimum is indicative of a successive development of two processes at condensate heating: desorption of initially sorbed oxygen atoms by silver nanoparticles (physical adsorption) and subsequent chemical adsorption with
further removal of gaseous dissociation products. At isothermal annealing of the condensate in air at 360° C for 1 hour the average size of silver particles practically does not change relative to initial dimensions. Just individual particles of a larger size of 300-400 nm appear. It should be noted that complication of the process of condensate deposition with oxygen feeding into the vacuum chamber during evaporation and condensation in the amount of 140 ml/min increases oxygen content in the condensate after loss of vacuum in the chamber. Ratio of atomic percent of O2 and Ag reaches 1.1, i.e. it is equivalent to AgOu. Example 2
Experimental procedure to produce copper-based nanoparticles is similar to example 1. Evaporation of NaCl and Cu was performed by the electron beam from two independent sources. Compacted Cu rod 2 of 48.5 mm diameter and 110 mm height was placed into cylindrical water-cooled crucible 1 with 50 mm inner diameter (Fig. 1), NaCl 4 was placed into adjacent crucible 3. Surface of both the rods was heated by electron beam guns 5 and 6 up to melting, which resulted in formation of mixed vapour flow 7 of Cu and NaCl. Condensation of mixed vapour flow was performed on flat iron substrate 8 at temperature Ts = 50 - 60° C in vacuum of 10"4 Torr (mm Hg). Condensation rate was equal to 4.5 - 5.0 μm/min. Condensate thickness was 100 - 120 μm.
Condensate oxidation occurred in air at the moment of loss of vacuum in the chamber. Condensate composition was as follows: copper - 25.3 wt.% (12.9 at.%), oxygen - 4.34 wt.% (8.8 at.%), NaCl being the balance. Ratio of atomic percent of oxygen and copper is equal to 0.68, allowing condensate composition to be conditionally presented as CuOo.68- X-ray structural analysis reveals NaCl and Cu2O phases. Average size of Cu2O particles in water solution with stabilizer addition is equal to 27 nm. Oxygen desorption (relative mass loss) at condensate heating at the rate of 10° C/min in air is shown in Fig. 5. Lowering of adsorbed oxygen content is over at approximately 350° C, reaching the value of 1.4 wt.% (2.03 at.%), i.e. 6.78 at.% oxygen and initial content of copper of 12.9 at.% remain
in the condensate, corresponding to composition of CuOo.53 or Cu2O. Isothermal annealing of initial condensates in air at 300° C and 400° C for 1 hour results in formation of CuO particles with average size of 35 - 40 nm.
Adsorbed oxygen content in the condensates decreases with increase of condensation temperature up to 150 - 200° C. Example 3
Method to produce iron-based nanoparticles was implemented similar to example 1. Compressed Fe rod 2 of 48.5 mm diameter and 80 mm height was placed into cylindrical water-cooled crucible 1 (Fig. 1) with inner diameter of 50 mm, and KCl 4 was placed into adjacent crucible 3. Vacuum of 10"4 Ton* (mm Hg) was created in the chamber. Surface of both the rods was heated by electron beam guns 5 and 6 up to melting, which resulted in formation of mixed vapour flow 7 of Fe and KCl, which was condensed at the rate of 15 - 16 μm/min on water-cooled flat substrate 8, where 40 - 50° C temperature was maintained. Condensate thickness was equal to 250 - 260 μm.
Condensate oxidation occurred in air during loss of vacuum in the chamber. Condensate composition was as follows: Fe - 20.1 wt.% (10.5 at.%); O2 - 13.3 wt.% (24.0 at.%); KCl being the balance. Ratio of atomic percent of oxygen and iron is equal to 2.29, allowing condensate composition to be conditionally presented at FeO2 29 or Fe2O4 58. X-ray structural analysis registers diffraction which is inherent only to KCl. Electron microscopy analysis of thin cleavages of the condensate revealed blurred diffraction rings of Fe3O4. Average size of particles of this phase is equal to 3 - 4 nm.
Thermogravimetric curve of these sample which describes oxygen desorption, is given in Fig. 6. Lowering of oxygen content is over at approximately 550° C, reaching the value of 5.6 wt.% (10.08 at.%), i.e. 13.9 at.% of oxygen and initial iron content of 10.5 at.% remain in the condensate. Ratio of 13.9/10.5 = 1.32 corresponds to Fe3O4 formula. Isothermal annealing of initial condensates in air at 200° C for 1 hour increases the average size of Fe3O4 particles up to 5 - 6 nm. At annealing at 400° C Fe2O3 phase also appears in addition to KCl and Fe3O4 phases.
Average size of particles is 5 — 7 run, but larger particles of 30 - 40 nm are also found. Annealing at 650° C for 10 min fixes KCl, Fe3O4 and Fe2O3 phases. Average particle size increases to 8 - 12 nm, and large particles increase to 20 - 60 nm. Example 4.
Experimental procedure is similar to previous examples. NaCl and Ti evaporation was conducted with electron beam from two independent sources. Condensation of mixed vapour flow was performed on a flat iron substrate at temperature of 40 - 50° C in vacuum of 5 10"5 Torr (mm Hg). Condensation rate was 8 - 9 μm/min. Condensate thickness was equal to approximately 100 μm.
Condensate oxidation occurred in air at the moment of loss of vacuum in the chamber. Condensate composition was as follows: titanium - 14.9 wt.% (8.3 at.%), oxygen - 18.1 wt.% (30.2 at.%), NaCl being the balance. Ratio of atomic percent of oxygen and titanium is equal to 3.6, allowing the condensate composition to be conditionally presented as TiO3 6. X-ray structural analysis registers only NaCl structure. Transmission electron microscopy analysis of thin cleavages of the condensate revealed also fine Ti particles. Average size of particles is 2 - 3 nm.
Oxygen desorption at condensate annealing in air is shown in Fig. 7. Lowering of oxygen content is over approximately at 650° C, reaching about 7.0 wt.% (11.7 at.%) at initial oxygen content of 30.2 at.%. Thus, 18.5 at.% of oxygen and initial titanium content of 8.3 at.% remain in the condensate, i.e. it corresponds to TiO2 2 composition. Isothermal annealing of initial condensate in air at 200° C is accompanied by appearance of TiO2 phase (rutile). At annealing at 400° C anatase appears in addition to NaCl and rutile phases. In the presence of fine fraction of particles, a larger fraction of up to 20-30 nm is found in individual zones. At annealing at 650° C, clear diffraction rings of polycrystalline structure of anatase are registered alongside titanium, and the coarser particle fraction increases up to dimensions of 30 - 70 nm.
It can be seen from the examples that condensation of nanoparticles in a solid porous environment allows a more precise fixation and preservation of their
size, and producing nanoparticles with a high- oxygen-to-metal ratio, where oxygen is at the stage of physical and chemical adsorption. Further heat treatment allows removing the remaining physically adsorbed oxygen and forming new phase systems. On the other hand, change of substrate temperature and temperature of further heat treatment allows adjustment and selection of the composition and size of the produced nanoparticles. Industrial applicability
The claimed method to produce nanoparticles of metal-oxygen system of a specified composition by electron beam evaporation and condensation in vacuum allows realizing it by simple techniques in the currently available equipment for electron beam evaporation of metals and alloys and does not requires additional highly expensive devices. On the other hand, the claimed method of producing nanoparticles of metal-oxygen system by electron beam evaporation and condensation in vacuum and nanopowders and colloid systems produced by this method are needed in medicine, ecology, food industry, chemical technology, micro- and nanoelectronics.
Moreover, application of the proposed method to produce nanoparticles of metal-oxygen system of certain specified composition by electron beam evaporation and condensation in vacuum allows an essential simplification of the processes of storage, transportation and preparation of solutions without violation of nanoparticle size with time.
Claims
1. Method to produce nanoparticles of metal-oxygen system of specified composition by electron beam evaporation and condensation in vacuum, which includes simultaneous heating and evaporation of solid initial material and solid carrier material from at least two separate vessels in the vacuum chamber, mixing of vapour flows of initial material and carrier, deposition in the condensation zone of mixed vapour flow on a substrate with fixing of initial material nanoparticles on the substrate by carrier material which solidifies, and formation of nanoparticle condensate in the carrier, characterized in that the initial material is selected from a group which includes metal and their alloys (Me), carrier material is selected from soluble in liquid and evaporable in vacuum without decomposition simple and complex inorganic substances selected from a group, which includes chlorides of sodium, potassium, calcium, magnesium, boron oxide, sodium metaborate and their mixtures, substrate temperature is set and maintained by dosed cooling in the range of formation of open micro- and nanosized porous structure of carrier material of not less than 0.5 of its melting temperature ( K) to create open micro- and nanosized porous structure of carrier material on the substrate and to produce a condensate of nanoparticles having an open surface, in the open micro- and nanosized porous structure of carrier material, dosed feed of oxygen /oxygen- containing gases, vapours and their mixtures into the vacuum chamber / condensation zone is performed to change nanoparticle chemical composition through physico-chemical interaction of open surface of initial material nanoparticles with oxygen, and to produce nanoparticles of metal-oxygen system of a specified composition.
2. Method according to Claim 1, characterized in that heating and evaporation of initial material are performed by laser radiation.
3. Method according to Claim 1, characterized in that radiation heating and evaporation of initial material and carrier material from ceramic vessels /crucibles/ are performed.
4. Method according to Claim 1, characterized in that dosed evaporation of carrier material is performed by changing the physical surface area of carrier material, which is placed into an open vessel.
5. Method according to Claim 1, characterized in that dosed evaporation of carrier material is performed in a closed vessel, through this vessel outlet.
6. Method according to Claim 1 , characterized in that ionization of initial material vapour flow is performed.
7. Method according to Claim 1, characterized in that dosed feed of oxygen / oxygen-containing gases, vapours and their mixtures into the vacuum chamber / condensation zone is performed after the process of deposition of mixed vapour flow on the substrate.
8. Method according to Claim 1, characterized in that dosed feed of oxygen / oxygen-containing gases, vapours and their mixtures into the condensation zone is performed during deposition of the mixed vapour flow on the substrate.
9. Method according to Claim 1, characterized in that additional high- temperature chemico-thermal treatment of metal-oxygen condensate in oxygen / oxygen-containing gases, vapours and their mixtures is performed.
10. Method according to Claim 1, characterized in that nanoparticle concentration in the above condensate is from 0.1 up to 30 vol.%.
11. Method according to Claim 1, characterized in that it additionally includes grinding and mixing of the above-mentioned produced condensate.
12. Method according to Claims 1-11, characterized in that the condensate is dissolved in at least one liquid, nanoparticles are stabilized in the above liquid by a surfactant dissolved in the above liquid, producing a colloid system of nanoparticles.
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| US5498446A (en) * | 1994-05-25 | 1996-03-12 | Washington University | Method and apparatus for producing high purity and unagglomerated submicron particles |
| ATE450631T1 (en) * | 2001-09-10 | 2009-12-15 | Univ Virginia | METHOD FOR APPLYING METAL ALLOY COATINGS AND COATED COMPONENT |
| US7556695B2 (en) * | 2002-05-06 | 2009-07-07 | Honeywell International, Inc. | Apparatus to make nanolaminate thermal barrier coatings |
-
2009
- 2009-06-10 UA UAA200905985A patent/UA92556C2/en unknown
-
2010
- 2010-05-18 WO PCT/UA2010/000027 patent/WO2010144070A2/en active Application Filing
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| UA82448C2 (en) | 2007-02-26 | 2008-04-10 | Институт электросварки им. Е.О. Патона национальной академии наук Украины | Method for production of encapsulated nanopowders and unit for implementation thereof |
Non-Patent Citations (3)
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| J.D.RAMSAY; R.G.AVERY: "Ultrafine oxide powder prepared by electron beam evaporation. Part 1 Evaporation and condensation process", JOURNAL OF MATERIALS SCIENCE, vol. 9, 1974, pages 1681 - 1688 |
| KIMOTO K.; KAMIYA Y.; NONOYAMA M.; UYEDA R.: "An Electron Microscope Study on Fine Metal Particles Prepared by Evaporation in Argon Gas at Low Pressure.", JPN. J. APPL. PHYS., vol. 2, 1963, pages 702 - 704 |
| NAKATAKI I.; FURUBAYASHI T.; TAKANASHI T.; HANAOKA H.: "Preparation and magnetic properties of colloidal ferromagnetic metals.", J. MAG. MAT., vol. 65, no. 283, 1987, pages 261 - 264 |
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| Publication number | Publication date |
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| UA92556C2 (en) | 2010-11-10 |
| WO2010144070A3 (en) | 2011-05-26 |
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