WO2009021820A1 - Nanosize structures composed of valve metals and valve metal suboxides and process for producing them - Google Patents
Nanosize structures composed of valve metals and valve metal suboxides and process for producing them Download PDFInfo
- Publication number
- WO2009021820A1 WO2009021820A1 PCT/EP2008/059659 EP2008059659W WO2009021820A1 WO 2009021820 A1 WO2009021820 A1 WO 2009021820A1 EP 2008059659 W EP2008059659 W EP 2008059659W WO 2009021820 A1 WO2009021820 A1 WO 2009021820A1
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- WO
- WIPO (PCT)
- Prior art keywords
- valve metal
- reduction
- structures
- metal
- valve
- Prior art date
Links
- 229910052751 metal Inorganic materials 0.000 title claims abstract description 92
- 239000002184 metal Substances 0.000 title claims abstract description 92
- 150000002739 metals Chemical class 0.000 title claims description 19
- 238000000034 method Methods 0.000 title claims description 12
- 230000008569 process Effects 0.000 title claims description 12
- 150000004706 metal oxides Chemical group 0.000 claims abstract description 34
- 230000009467 reduction Effects 0.000 claims description 50
- 229910044991 metal oxide Inorganic materials 0.000 claims description 33
- 239000000843 powder Substances 0.000 claims description 22
- 229910052758 niobium Inorganic materials 0.000 claims description 9
- 229910052715 tantalum Inorganic materials 0.000 claims description 9
- 229910052782 aluminium Inorganic materials 0.000 claims description 6
- 239000011888 foil Substances 0.000 claims description 6
- 229910052749 magnesium Inorganic materials 0.000 claims description 6
- 229910052719 titanium Inorganic materials 0.000 claims description 4
- 230000009466 transformation Effects 0.000 claims description 4
- 229910052720 vanadium Inorganic materials 0.000 claims description 4
- 229910052726 zirconium Inorganic materials 0.000 claims description 4
- 229910045601 alloy Inorganic materials 0.000 claims description 3
- 239000000956 alloy Substances 0.000 claims description 3
- 229910052735 hafnium Inorganic materials 0.000 claims description 3
- 229910052750 molybdenum Inorganic materials 0.000 claims description 3
- 229910052721 tungsten Inorganic materials 0.000 claims description 2
- 239000011261 inert gas Substances 0.000 claims 1
- 238000005979 thermal decomposition reaction Methods 0.000 claims 1
- 238000006722 reduction reaction Methods 0.000 description 46
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 10
- 238000006243 chemical reaction Methods 0.000 description 9
- 239000011164 primary particle Substances 0.000 description 9
- 239000002245 particle Substances 0.000 description 8
- 239000011148 porous material Substances 0.000 description 8
- 239000000758 substrate Substances 0.000 description 8
- 239000011777 magnesium Substances 0.000 description 6
- 239000000047 product Substances 0.000 description 6
- 229910052786 argon Inorganic materials 0.000 description 5
- 239000012159 carrier gas Substances 0.000 description 5
- 239000010955 niobium Substances 0.000 description 5
- 238000009834 vaporization Methods 0.000 description 5
- 230000008016 vaporization Effects 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 4
- 238000001354 calcination Methods 0.000 description 3
- 239000003990 capacitor Substances 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 238000009792 diffusion process Methods 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 150000007513 acids Chemical class 0.000 description 2
- 239000010405 anode material Substances 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 2
- 239000007795 chemical reaction product Substances 0.000 description 2
- 239000000112 cooling gas Substances 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 239000001307 helium Substances 0.000 description 2
- 229910052734 helium Inorganic materials 0.000 description 2
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 2
- 150000004679 hydroxides Chemical class 0.000 description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000011707 mineral Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical group [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 1
- 238000003917 TEM image Methods 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000005496 eutectics Effects 0.000 description 1
- 238000011010 flushing procedure Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000007943 implant Substances 0.000 description 1
- 238000010884 ion-beam technique Methods 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- 239000000395 magnesium oxide Substances 0.000 description 1
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 1
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 239000002923 metal particle Substances 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 229910052756 noble gas Inorganic materials 0.000 description 1
- 150000002835 noble gases Chemical class 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- BPUBBGLMJRNUCC-UHFFFAOYSA-N oxygen(2-);tantalum(5+) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ta+5].[Ta+5] BPUBBGLMJRNUCC-UHFFFAOYSA-N 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000011946 reduction process Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000007784 solid electrolyte Substances 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 239000011232 storage material Substances 0.000 description 1
- 239000001117 sulphuric acid Substances 0.000 description 1
- 235000011149 sulphuric acid Nutrition 0.000 description 1
- PBCFLUZVCVVTBY-UHFFFAOYSA-N tantalum pentoxide Inorganic materials O=[Ta](=O)O[Ta](=O)=O PBCFLUZVCVVTBY-UHFFFAOYSA-N 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/16—Making metallic powder or suspensions thereof using chemical processes
- B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
- B22F9/20—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds
- B22F9/22—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds using gaseous reductors
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/07—Metallic powder characterised by particles having a nanoscale microstructure
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B34/00—Obtaining refractory metals
- C22B34/20—Obtaining niobium, tantalum or vanadium
- C22B34/24—Obtaining niobium or tantalum
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B5/00—General methods of reducing to metals
- C22B5/02—Dry methods smelting of sulfides or formation of mattes
- C22B5/04—Dry methods smelting of sulfides or formation of mattes by aluminium, other metals or silicon
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
- H01G9/004—Details
- H01G9/04—Electrodes or formation of dielectric layers thereon
- H01G9/048—Electrodes or formation of dielectric layers thereon characterised by their structure
- H01G9/052—Sintered electrodes
- H01G9/0525—Powder therefor
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B34/00—Obtaining refractory metals
- C22B34/10—Obtaining titanium, zirconium or hafnium
- C22B34/12—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08
- C22B34/1263—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 obtaining metallic titanium from titanium compounds, e.g. by reduction
- C22B34/1268—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 obtaining metallic titanium from titanium compounds, e.g. by reduction using alkali or alkaline-earth metals or amalgams
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
- H01G9/004—Details
- H01G9/04—Electrodes or formation of dielectric layers thereon
- H01G9/048—Electrodes or formation of dielectric layers thereon characterised by their structure
- H01G9/052—Sintered electrodes
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/12—All metal or with adjacent metals
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/12—All metal or with adjacent metals
- Y10T428/12431—Foil or filament smaller than 6 mils
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/12—All metal or with adjacent metals
- Y10T428/12431—Foil or filament smaller than 6 mils
- Y10T428/12438—Composite
Definitions
- the present invention relates to novel lamellar structures of valve metals and valve metal suboxides which have a dimension of less than 100 mm in one direction and a process for producing them.
- Fine structures composed of metals and metal suboxides which are present in powders or surface regions of larger metal substrates have a wide variety of uses as catalysts, support materials for catalysts, in the field of membrane and filter technology, in the medical sector as implant material, as storage materials in secondary batteries and as anode material of capacitors because of their large specific surface area.
- WO 00/67936 discloses a process for producing finely divided valve metal powders by reduction of valve metal oxide powders by means of gaseous reducing metals such as Mg, Al, Ca, Li and Ba. Owing to the volume shrinkage in the reduction of the oxide to the metal and the volume increase caused by the solid oxides of the reducing metals which are formed, highly porous valve metal powders having a high specific surface area which are suitable, in particular, for producing solid electrolyte capacitors are formed.
- gaseous reducing metals such as Mg, Al, Ca, Li and Ba.
- Dissolution and leaching of the oxide of the reducing metal in mineral acids enables the nanosize valve metal structures to be freed of the oxide of the reducing metal.
- finely divided powders having a lamellar structure or strip-like or lamellar surface structures on metal substrates having relatively coarse/large structures are obtained, with the metal and/or suboxide strips or lamellae having a width of less than 100 nm and a spacing (intermediate space) which can be up to twice the strip width, depending on the valve metal oxide and the oxidation state which it attains.
- finely divided valve metal oxide powders having average dimensions of the primary structure particle size of from 50 to 2000 nm, preferably less than 500 nm, more preferably less than 300 nm, are used, finely divided metal or suboxide powders having a lamellar structure and a width of the metal or suboxide strips of from 5 to 100 nm, preferably from 8 to 50 nm, particularly preferably up to 30 nm, and transverse dimensions of from 40 to 500 nm and a specific surface area of above 20 m 2 /g, preferably above 50 m 2 /g, are obtained.
- metallic or suboxidic strips having a width of up to 100 nm, preferably from 5 to 80 nm, particularly preferably from 8 to 50 nm, more preferably up to 30 nm, and spacings of from one to two times the strip width are obtained on these structures.
- the depth of the grooves between the strips can be up to 1 ⁇ m.
- Relatively large metal structures or substrates, for example wires or foils, having a strip-like surface can be obtained by firstly oxidizing the surface chemically or anodically and then reducing the surface according to the invention, with the strip depth being determined by the thickness of the oxide layer initially produced.
- structures according to the invention can be obtained by providing a substrate comprising, for example, another metal or ceramic with a valve metal oxide layer, for example by application of a valve metal layer by vapour deposition or electrolytic deposition, oxidizing the coating and reducing it according to the invention to the metal or suboxide.
- Valve metal oxides used for the purposes of the present invention can be oxides of the elements of transition groups 4 to 6 of the Periodic Table, e.g. Ti, Zr, V, Nb, Ta, Mo, W and Hf, and also their alloys (mixed oxides) and Al, preferably Ti, Zr, Nb and Ta, particularly preferably Nb and Ta.
- starting oxides preference is given to, in particular, Nb2 ⁇ 5 , Nb ⁇ 2 and Ta2 ⁇ 5 .
- Preferred reaction products according to the invention are the metals of the starting oxides. Lower oxides (suboxides) of the starting valve metal oxides can also be obtained as reduction products.
- a particularly preferred reduction product is niobium suboxide having metallically conducting properties of the formula NbO x where 0.7 ⁇ x ⁇ 1.3, which, in addition to tantalum and niobium, is suitable as anode material for capacitors, according to the invention particularly for use in the range of low activation voltages up to 10 V, particularly preferably up to 5 V, in particular up to 3 V.
- Li, Mg, Ca, B, and/or Al and their alloys according to the invention Preference is given to Mg, Ca and Al, as long as these are less noble than the metals of the starting oxides. Very particular preference is given to Mg or a eutectic of Mg and Al.
- a characteristic of the reduction products according to the invention is their content of reducing metals in the range above 10 ppm, in particular from 50 to 500 ppm, owing to doping during reduction.
- the process of the invention by which the nanosize structures can be produced is based on reduction of metal oxides by reducing metals in vapour form as described in WO 00/67936.
- the valve metal oxide to be reduced in powder form is brought into contact with the vapour of the reducing metal in a reactor.
- the reducing metal is vaporized and conveyed by means of a carrier gas stream such as argon over the valve metal oxide powder present on a mesh or in a boat at elevated temperature, typically from 900 to 1200 0 C, likewise typically for a period of from 30 minutes to some hours. Since the molar volume of valve metal oxides is from two to three times the volume of the corresponding valve metal, a considerable decrease in volume takes place during reduction.
- Sponge-like, highly porous structures in which the oxide of the reducing metal is deposited are therefore formed in the reduction. Since the molar volumes of the oxides of the reducing metals are greater than the difference between the molar volumes of the valve metal oxide and the valve metal, they are incorporated into the pores with production of residual stresses. The structures can be freed of the oxides of the reducing metals by dissolution of these oxides, so as to obtain highly porous metal powders. Studies on the mechanism of the reduction and the formation of the pores and their distribution have shown the following: starting from small reaction nuclei on the surface of the valve metal oxide particles or substrates, layer-like structures having nanosize dimensions are formed behind the valve metal/valve metal oxide reaction front in the initial phase of the reaction.
- the layers are firstly oriented perpendicular to the surface in regions of the particles/substrates close to the surface.
- orientation and dimensions of the lamellae are determined by the crystal orientation and dimensions of the primary particles in the valve metal oxide and by the reaction conditions.
- a certain number of lattice planes in a valve metal oxide crystallite are replaced by a stoichiometrically equivalent number of lattice planes of the valve metal and of the oxide of the reducing metal.
- the lamellar structures can be frozen if care is taken to ensure that the reduction product is cooled to a temperature at which the lamellar structures remain stable before transformation of the structures occurs.
- the reduction conditions are therefore set so that the reduction can proceed very uniformly within a short time, i.e. if a pulverulent starting oxide is used, within the powder bed of the oxide and the reduction product is cooled as quickly as possible immediately after the reduction is complete.
- the thickness of the powder bed is particularly preferably less than 1 cm, more preferably less than 0.5 cm.
- the reduction is therefore preferably carried out under reduced pressure, more preferably in the absence of carrier gases.
- the reduction is particularly preferably carried out at a vapour pressure of the reducing metal of from 10 ⁇ 2 to 0.4 bar, more preferably from 0.1 to 0.3 bar, in the absence of oxygen.
- a low carrier gas pressure of up to 0.2 bar, preferably less than 0.1 bar, can be accepted without disadvantages.
- Suitable carrier gases are, in particular, noble gases such as argon and helium and/or hydrogen.
- the increase in depth of the lamellar structures decreases with increasing depth as a result of the longer diffusion path along the interface between reduced metallic lamellae and the oxide of the reducing metal formed between the metallic lamellae. It has been found that essentially no transformation of the lamellar structure takes place during the reduction up to a depth in the material of up to 1 ⁇ m.
- valve metal oxide powders whose smallest cross-sectional dimension of the primary structure particle size (crystallite dimension) does not exceed 2 ⁇ m, preferably 1 ⁇ m, particularly preferably an average of 0.5 ⁇ m.
- the valve metal oxide powders can be used as porous sintered agglomerates if the primary structures have appropriately small dimensions. It is also advantageous for the primary particles to be sintered together strongly but a hierarchically structured network of open pores to be present between the agglomerated primary particles, so that the pore size distribution of the open pores makes it possible for the vapour of the reducing metal to directly reach and reduce a very large proportion of the surfaces of the primary particles.
- metal foils or wires having a lamellar surface structure preference is given to using metal foils or wires whose surface has an oxide layer having a thickness of less than 1 ⁇ m, preferably less than 0.5 ⁇ m.
- the reduction under subatmospheric pressure which can take from a few minutes to some hours, preferably from about 10 to 90 minutes, depending on the reducing metal vapour or metal vapour mixture used and its vapour pressure, the reduction is stopped by interrupting the supply of the vapour of the reducing metal and the reduced valve metal is quickly cooled to a temperature below 100 0 C in order to stabilize the nanosize lamellar structure of layers of valve metal or valve metal suboxide and oxide of the reducing metal.
- Cooling can be brought about, for example, by means of a fast pressure increase by introduction of protective gas (cooling gas), preferably argon or helium. Preference is given to cooling to 300 0 C within 3 minutes, further to 200°C within a further 3 minutes and further to 100 0 C within a further 5 minutes.
- protective gas preferably argon or helium.
- the reduction is preferably carried out at a comparatively low temperature to minimize coarsening of the nanosize lamellar structures.
- a temperature of the valve metal oxide to be reduced of from 500 to 850 0 C, more preferably less than 750 0 C, particularly preferably less than 650 0 C, is preferred.
- the actual temperature can be considerably exceeded at the beginning of the reduction because of the exothermic nature of the reduction reaction.
- Starting valve metal oxide powder agglomerates having an advantageous open- pore structure require less stringent process conditions to achieve the lamellar structure according to the invention.
- the enclosed oxide of the reducing metal can be leached from the resulting nanosize structure, for example by means of mineral acids such as sulphuric acid or hydrochloric acid or mixtures thereof, washed with demineralized water until neutral and dried.
- these comprise particles having a tabular primary structure which are partly grown into one another in a dendrite-like fashion.
- the now freestanding lamellar structures of the valve metals remain geometrically stable since they are sufficiently well sintered to the adjacent, generally differently oriented lamellar structures via the end parts of the individual layers.
- the original (polycrystalline) valve metal oxide particle has thus been converted into an aggregated valve metal particle whose primary particles comprise layer structure groups of differing orientation and which are sintered to one another. Overall, a stable interpenetrating structure of metal and "flat" pores has thus been formed.
- Fig. 1 schematically shows an apparatus for carrying out the process of the invention.
- the reactor which is generally denoted by 1 has a reduction chamber 2.
- Reference numeral 3 denotes the temperature control which comprises heating coils and cooling coils.
- Protective or flushing gas or cooling gas is introduced via a valve into the reduction chamber in the direction of the arrow 4.
- the reduction chamber is evacuated or gases are taken off in the direction of the arrow 5.
- the reduction chamber 2 is joined by a vaporization chamber 6 for the reducing metal which is provided with separate heating 7.
- the thermal separation of vaporization chamber and reduction chamber is effected by means of the valve region 8.
- the valve metal oxide to be reduced is present as a thin powder bed in the boat 10.
- valve metal oxide foils or wires or foils or wires having a surface composed of valve metal oxide are used, these are preferably suspended vertically and parallel to the flow of the vapour of the reducing metal in the reduction chamber.
- the reducing metal in the boat 9 is heated to a temperature which provides the desired vapour pressure.
- the oxide powder is introduced as a bed having a height of 5 mm in a boat.
- a boat containing magnesium turnings is placed in the vaporization chamber.
- the reactor is flushed with argon.
- the reduction chamber is then heated to the reduction temperature and evacuated to a pressure of 0.1 bar.
- the vaporization chamber is subsequently heated to 800 0 C.
- the magnesium vapour pressure (static) is about 0.04 bar.
- the heating of reduction chamber and vaporization chamber is switched off and argon which has been cooled by depressurization from 200 bar is introduced and passed through the reduction chamber for a further period.
- the reduction chamber walls are at the same time cooled by means of water.
- Figures 2, 3 and 4 show transmission electron micrographs of tantalum powder which has been reduced according to the invention after focused ion beam preparation of the reduction product at various magnifications.
- the dark stripes in the figures are tantalum lamellae and the light-coloured stripes are magnesium oxide lamellae.
- the different orientations of the lamellar structures correspond to different crystallite orientations of the starting tantalum pentoxide.
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Power Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Crystallography & Structural Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Nanotechnology (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Manufacture Of Metal Powder And Suspensions Thereof (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
- Powder Metallurgy (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
- Oxygen, Ozone, And Oxides In General (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
Description
Claims
Priority Applications (7)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR1020107003852A KR101530727B1 (en) | 2007-08-16 | 2008-07-23 | Nanosize structures composed of valve metals and valve metal suboxides and process for producing them |
JP2010520521A JP5542672B2 (en) | 2007-08-16 | 2008-07-23 | Nanosize structure comprising valve metal, valve metal suboxide, and manufacturing method thereof |
MX2010001586A MX2010001586A (en) | 2007-08-16 | 2008-07-23 | Nanosize structures composed of valve metals and valve metal suboxides and process for producing them. |
EP08786351A EP2188081A1 (en) | 2007-08-16 | 2008-07-23 | Nanosize structures composed of valve metals and valve metal suboxides and process for producing them |
RU2010109437/02A RU2493939C2 (en) | 2007-08-16 | 2008-07-23 | Nanostructures consisting of gate metals and gate metal sub oxides and methods of their production |
US12/673,559 US20110123822A1 (en) | 2007-08-16 | 2008-07-23 | Nanosize structures composed of valve metals and valve metal suboxides and process for producing them |
CN200880103432A CN101778683A (en) | 2007-08-16 | 2008-07-23 | Nanostructured of forming by valve metal and valve metal protoxide and preparation method thereof |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102007038581A DE102007038581A1 (en) | 2007-08-16 | 2007-08-16 | Valve metal structure and valve metal sub-oxide structure, have lateral dimension of 5 to 10 nanometers and are expanded in streaky or flat manner and valve metal structures are in form of foils or wires |
DE102007038581.3 | 2007-08-16 | ||
DE102007057761A DE102007057761A1 (en) | 2007-11-30 | 2007-11-30 | Strip-like or sheet-like valve metal and valve metal suboxide structures in the form of surface strip structures, foils, or wires, useful e.g. as catalysts and support materials for catalysts, have specified transverse dimension |
DE102007057761.5 | 2007-11-30 |
Publications (1)
Publication Number | Publication Date |
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WO2009021820A1 true WO2009021820A1 (en) | 2009-02-19 |
Family
ID=40139278
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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PCT/EP2008/059659 WO2009021820A1 (en) | 2007-08-16 | 2008-07-23 | Nanosize structures composed of valve metals and valve metal suboxides and process for producing them |
Country Status (9)
Country | Link |
---|---|
US (1) | US20110123822A1 (en) |
EP (1) | EP2188081A1 (en) |
JP (1) | JP5542672B2 (en) |
KR (1) | KR101530727B1 (en) |
CN (2) | CN104889381A (en) |
MX (1) | MX2010001586A (en) |
RU (1) | RU2493939C2 (en) |
TW (1) | TWI477437B (en) |
WO (1) | WO2009021820A1 (en) |
Cited By (2)
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RU2596513C1 (en) * | 2015-05-15 | 2016-09-10 | Федеральное государственное бюджетное учреждение науки Институт химии и технологии редких элементов и минерального сырья им. И.В. Тананаева Кольского научного центра Российской академии наук (ИХТРЭМС КНЦ РАН) | Method of producing molybdenum powder |
US10927433B2 (en) | 2016-08-02 | 2021-02-23 | Sri Lanka Institute of Nanotechnology (Pvt) Ltd. | Method of producing titanium from titanium oxides through magnesium vapour reduction |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
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CN106623980B (en) * | 2016-09-18 | 2019-06-18 | 华南理工大学 | A kind of preparation method of metal molybdenum nanometer sheet |
US20190040503A1 (en) * | 2017-08-03 | 2019-02-07 | Hrl Laboratories, Llc | Feedstocks for additive manufacturing, and methods of using the same |
WO2019139554A1 (en) | 2018-01-10 | 2019-07-18 | Aselsan Elektronik Sanayi Ve Ticaret Anonim Sirketi | A production method for a metallic material with high surface area nanostructures |
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- 2008-07-23 US US12/673,559 patent/US20110123822A1/en not_active Abandoned
- 2008-07-23 JP JP2010520521A patent/JP5542672B2/en not_active Expired - Fee Related
- 2008-07-23 CN CN201510198881.7A patent/CN104889381A/en active Pending
- 2008-07-23 WO PCT/EP2008/059659 patent/WO2009021820A1/en active Application Filing
- 2008-07-23 MX MX2010001586A patent/MX2010001586A/en active IP Right Grant
- 2008-07-23 KR KR1020107003852A patent/KR101530727B1/en not_active IP Right Cessation
- 2008-07-23 RU RU2010109437/02A patent/RU2493939C2/en not_active IP Right Cessation
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Also Published As
Publication number | Publication date |
---|---|
TWI477437B (en) | 2015-03-21 |
KR101530727B1 (en) | 2015-06-22 |
EP2188081A1 (en) | 2010-05-26 |
TW200927641A (en) | 2009-07-01 |
JP2010537040A (en) | 2010-12-02 |
JP5542672B2 (en) | 2014-07-09 |
KR20100065280A (en) | 2010-06-16 |
CN104889381A (en) | 2015-09-09 |
RU2493939C2 (en) | 2013-09-27 |
RU2010109437A (en) | 2011-09-27 |
US20110123822A1 (en) | 2011-05-26 |
CN101778683A (en) | 2010-07-14 |
MX2010001586A (en) | 2010-03-15 |
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