MXPA01002770A - Methods to partially reduce certain metal oxides and oxygen reduced metal oxides - Google Patents

Abstract

Methods to at least partially reduce valve metal oxides are described wherein the process includes heat treating the valve metal oxide in the presence of the getter material, in an atmosphere which permits the transfer of oxygen atoms from the starting valve metal oxide to the getter material, and for a sufficient time and at a sufficient temperature to form an oxygen reduced valve metal oxide. Valve metal oxides and/or suboxides thereof are also described as well as capacitors containing anodes made from the valve metal oxides and suboxides thereof.

Description

METHODS TO PARTIALLY REDUCE CERTAIN OXIDES OF METAL AND OXIDES REDUCED BY OXYGEN Field of the Invention The present invention relates to valve metals, other metals, and oxides thereof and more particularly relates to methods for at least partially reducing metal oxides and further relates to valve metals with reduced oxygen and other metals.

BACKGROUND OF THE INVENTION In accordance with the purposes of the present invention, as incorporated and described herein, the present invention relates to a method for at least partially reducing a metal oxide selected from a valve metal oxide, which includes the steps of heat treatment of the metal oxide in the presence of a metallic absorbent material such as a tantalum and / or metallic niobium absorbent material, or other metallic absorbent material with the ability to reduce metal oxide, in an atmosphere which allows the transfer of oxygen atoms from the metal oxide to the metallic absorbent material, for a period of time and temperature, sufficient to form a valve metal oxide with reduced oxygen.

Summary of the Invention The present invention also relates to valve oxides with reduced oxygen which preferably have beneficial properties, especially when formed in an electrolytic capacitor anode. For example, a capacitor made of a reduced oxygen valve metal oxide of the present invention may have a capacitance of about 1,000 CV / g or less than about 200,000 CV / g or greater. In addition, the electrolytic capacitor anodes made of reduced oxygen valve metal oxides of the present invention may have a low DC direct current filtration. For example, said capacitor may have a CD filtration of approximately 5.0 nA / CV to approximately 0.5 nA / CV. Accordingly, the present invention also relates to methods for increasing the capacitance and reducing the filtration of DC in capacitors made of valve metal oxides, which comprises the partial reduction of a valve metal oxide by means of heat treatment of the valve. valve metal oxide in the presence of a metallic absorbent material, such as tantalum and / or metallic niobium absorbent material, and in an atmosphere which allows the transfer of the oxygen atoms from the metal oxide to the metallic absorbent material for a period of time and temperature sufficient to form a valve metal oxide with reduced oxygen, which when formed on a capacitor anode, has reduced CD filtration and / or increased capacitance. It should be understood that both the foregoing general description and the following detailed description are provided by way of example and explanation only and are intended to provide a further explanation of the present invention, as claimed.

Brief Description of the Drawings Figures 1 to 14 are SEMs of various reduced oxygen valve metal oxides of the present invention in different magnifications.

Detailed Description of the Invention In one embodiment of the present invention, this relates to methods for at least partially reducing a valve metal oxide. In general, the process includes the steps of thermal treatment of the valve metal oxide in the presence of a metallic absorbent material, which is preferably tantalum and / or metal absorbent material of niobium or other metallic absorbent material depending on the metal oxide that it is being reduced, in an atmosphere which allows the transfer of the oxygen atoms of the metal oxide to the metallic absorbent material, for a sufficient period of time and a temperature sufficient to form a valve metal oxide with reduced oxygen. For purposes of the present invention, examples of the starting valve metal oxides may be, but are not limited to, at least one oxide of the metals of Groups 4, 5, and 6.

(IUPAC designations) of the Periodic Table, aluminum, bismuth, antimony and alloys thereof and combinations thereof. Preferably, the valve metal oxide is an oxide of tantalum, aluminum, titanium, zirconium, niobium and / or alloys thereof and more preferably is a niobium oxide, a tantalum oxide, or alloys thereof. Generally, alloys of valve metal oxides will have valve metal as the predominant metal present in the alloy oxide. Specific examples of the starting valve metal oxides include, but are not limited to Nb20s, Ta205 and A1203. The metal oxide can also be a metal oxide which is a semiconductor as a lower oxide and which is converted into a higher oxide with high insulating properties and has useful dielectric properties. The valve metal oxide used in the present invention can be of any shape or size. Preferably, the valve metal oxide is in the form of a powder or a plurality of particles. Examples of the types of powder that may be used include, but are not limited to, shavings, angular, nodular and mixtures or variations thereof. Preferably, the valve metal oxide is in the form of a powder which leads in a more effective manner to the oxides of valve metal with reduced oxygen. Examples of such preferred metal oxide powders include those having mesh sizes of about 60/100 to about 100/325 and mesh sizes of about 60/100 to about 200/325. Another size range is from about 40 mesh to about 325 mesh. The metal absorbent material for purposes of the present invention is a material that has the ability to reduce the specific starting valve metal oxide. Preferably, the starting metal oxides such as tantalum or niobium, and the like, and the metal absorbent material is tantalum or niobium. More preferably, the metal absorbent material is of the same type of the basic material as the starting metal oxide. The metal tantalum absorbent material is any material that contains tantalum metal which can remove or at least partially reduce the oxygen in the valve metal oxide. Thus, the tantalum metal absorbent material may be an alloy or a material containing mixtures of tantalum metal with other ingredients. Preferably, the metal tantalum absorbent material is predominantly, if not exclusively, tantalum metal. The purity of the tantalum metal is not important, but it is preferred that the tantalum metal has high purity comprising a metallic absorbent material to prevent the introduction of other impurities during the heat treatment process. Accordingly, the tantalum metal is a metallic tantalum absorbing material which preferably has a purity of at least about 98% and more preferably at least about 99%. In addition, it is preferred that impurities, such as oxygen, are not present or present in amounts less than about 100 ppm. Also, the tantalum metal as a metallic absorbent material can have a high surface area and / or high porosity. Preferably, the tantalum or other metallic absorbent material is a material of capacitor grade such as tantalum having a capacitance capacity of about 30,000 Cv / g or more and more preferably about 50,000 Cv / g or more and even more preferably about 75,000 Cv /. ga approximately 100,000 Cv / g or more. The metallic absorbent material can be removed after it has been used or it can remain. Preferably, if the metal absorbent material is to remain with the oxides of metal with reduced oxygen, then it is preferred that the metal absorbent material be of the same basic material as the starting metal oxide and have a shape and size similar to metal oxide. of departure. further, a high purity metallic absorbent material, high surface area, and high porosity is used since said material will obtain the same or similar oxidation condition as the oxidized metal oxide. Therefore, the method will achieve a 100% yield of metal oxide with reduced oxygen. Therefore the metallic absorbent material can act as a metallic absorbent material and also remain to be part of the niobium oxide with reduced oxygen. The present invention can extend the amount of tantalum and other valve metal in products, such as capacitors since an anode containing tantalum oxide with reduced oxygen (or other metal oxide of capacitor grade) contains less tantalum than the same anode that has only tantalum metal. In addition, the properties that can be obtained are similar, such as capacitance, and CD filtering capabilities. This advantage can lead to cost savings and other advantages to capacitor manufacturers. The metallic tantalum absorbent material can have any shape or size. For example, the metal tantalum absorbent material can be in the form of a tray which contains the metal oxide to be reduced or can be of a particle size or powder. Preferably, the metal tantalum absorbent materials are in the form of a powder, in order to have a more efficient surface area for the reduction of the metal oxide. The metal tantalum absorbent material, therefore, may be in the form of chips, angular, nodular and mixtures or variations thereof. Preferably, the metal absorbent material is a tantalum hydride material. A preferred form is thick chips, for example, 14/40 mesh chips that can be easily separated from the powder product by means of casting.

In a similar manner, the metallic absorbent material can be niobium and the like and can have the same preferred parameters and / or properties mentioned above for the metal tantalum absorbent material. Other metallic absorbent materials can be used alone or in combination with metallic absorbent materials of tantalum or niobium eg magnesium, sodium, potassium and the like. Again, these types of metal absorbent materials may contain other metallic absorbent materials and / or other ingredients. For purposes of the present invention, the metal absorbent material is stable during the heat treatment step and can not be volatilized at the heat treatment temperatures used for the specific starting valve metal oxide that is being reduced. Also, other materials can form a part of the metal absorbent material. Generally, a sufficient amount of the metal absorbent material (e.g., metallic oxygen absorbing material) is present to at least partially reduce the valve metal oxide being treated. In addition, the amount of the metal absorbent material depends on the amount of reduction desired for the metal oxide. For example, if a slight reduction in the metal oxide is desired, then the metallic absorbent material will be present in a stoichiometric amount. In a similar manner, if the metal oxide is to be substantially reduced with respect to its presence of oxygen, then the metallic absorbent material is present in a stoichiometric amount of 2 to 5 times. As an example, the amount of metallic absorbent material present (for example, based on a metallic tantalum absorbing material that is 100% tantalum and Ta205 as metal oxide) as a proportion of the metal absorbent material to the amount of oxide metal present can to be from about 2 to 1 to about 10 to 1. Additionally, the amount of metallic absorbent material may also depend on the type of metal oxide being reduced. For example, when it is a niobium oxide (e.g., Nb205) that is being reduced, the amount of metal absorbent material is preferably 5 to 1. When the starting valve metal oxide is Ta205 the amount of absorbent material The metal treatment is preferably 3 to 1. The heat treatment to which the starting metal oxide is subjected can be conducted in any heat treatment apparatus and furnace generally used in the heat treatment of metals, such as niobium and tantalum. The heat treatment of the metal oxide in the presence of the metal absorbent material is at a sufficient temperature and for a sufficient time to form a valve metal oxide with reduced oxygen. The temperature and time of the heat treatment may depend on a variety of factors, such as the amount of reduction of the valve metal oxide, the amount of the metal absorbent material and, the type of metal absorbent material as well as the type of the metal oxide. starting metal. The heat treatment can be at any temperature which allows the reduction of the starting valve metal oxide and which is lower than the melting point of the valve metal oxide that is being reduced. Generally, the heat treatment of the starting metal oxide will be at a temperature of about 800 ° C or less than about 1900 ° C and more preferably from about 1000 ° C to about 1400 ° C, and even more preferably about 1100 ° C. at approximately 1250 ° C. In more detail, when the valve metal oxide is a tantalum containing oxide, the heat treatment temperatures will be from about 1000 ° C to about 1300 ° C, and more preferably from about 1100 ° C to about 1250 ° C for a approximately 5 minutes to approximately 100 minutes, and more preferably from about 30 minutes to about 60 minutes. The routine tests in view of the present application will allow an expert in the field to easily control the times and temperatures of the thermal treatment in order to obtain the correct or desired reduction of the metal oxide. The heat treatment occurs in an atmosphere which allows the transfer of the oxygen atoms from the metal oxide to the metallic absorbent material. Heat treatments preferably occur in an atmosphere containing hydrogen in which it is preferably only hydrogen. Other gases with hydrogen may also be present, such as inert gases, insofar as the other gases do not react with hydrogen. Preferably, the hydrogen atmosphere is present during the heat treatment at a pressure of about 10 Torr to about 2000 Torr, and more preferably from about 100 torr to about 1000 Torr, and still more preferably from about 100 Torr to about 930 Torr. Mixtures of H2, and an inert gas such as Ar can be used. H2 can also be used in N2 to control the N2 level of the valve metal oxide. During the heat treatment process, a constant heat treatment temperature may be used during the entire process or variations in temperature or temperature steps may be used. For example, hydrogen can be admitted initially at a temperature of 1000 ° C followed by an increase in temperature to 1250 ° C for 30 minutes, followed by a reduction in temperature to 1000 ° C and sustained there until the gas is removed H2. After the H2 or other atmosphere has been removed, the oven temperature can be lowered. They can use variations of these steps to adapt any industry preferences. Metal oxides with reduced oxygen may also contain nitrogen levels, for example, from about 100 ppm to about 30,000 ppm N2. The valve metal oxide with reduced oxygen is any metal oxide which has a lower oxygen content in the metal oxide compared to the starting valve metal oxide. Generally, valve metal oxides with reduced oxygen comprise: NbO, NbO07, NbOi.i, Nb02, TaO, AIO, Ta60, Ta20, Ta202.2, or any combination thereof with or without other oxides present. Generally, the reduced metal oxide of the present invention has an atomic ratio of metal to oxygen of about 1: less than 2.5, and preferably 1: 2 and more preferably 1: 1.1, 1: 1, or 1: 0.7.

Expressed in another way, the reduced metal oxide preferably has the formula Mx0y, where M is the valve metal, x is 2 or less, and e is less than 2.5x. More preferably x is 1 and e is less than 2, such as 1.1, 1.0, 0.7, and the like. Preferably, when the reduced valve metal oxide is tantalum, the reduced metal oxide has an atomic ratio of metal to oxygen of about 1: less than 2, such as 1: 0.5, 1: 1, or 1: 0.167 or has a ratio of 2: 2.2. The starting valve metal oxides can be prepared by calcination at a temperature of 1000 ° C until the removal of any volatile components. The particles of the oxides can be selected in their sizes by casting. The preheating treatment of the oxides can be used to create controlled porosity in the oxide particles. The reduced metal oxides of the present invention also preferably have a microporous surface and preferably have a structure similar to the sponge, wherein the main particles are about one or less. The reduced metal oxides of the present invention preferably have a high specific surface area, and a porous structure with a porosity of about 50%. In addition, the reduced metal oxides of the present invention can be characterized as having a preferred specific surface area of from about 0.5 to about 10.0 m2 / g, more preferably from about 0.5 to about 2.0m2 / g, and still more preferably from approximately 1.0 to approximately 1.5m2 / g. The preferred bulk density of the metal oxide powder is less than about 2.0 g / cc, more preferably, less than 1.5 g / cc and still more preferably from about 0.5 to about 1.5 g / cc. The various reduced oxygen valve metal oxides of the present invention can be further characterized by the electrical properties resulting from the formation of a capacitor anode using the oxidized metal oxides of the present invention. In general, the oxidized metal oxides of the present invention can be tested for their electrical properties by compressing powders of the reduced oxygen metal oxides within an anode and sintering the compressed powders at appropriate temperatures and then anodizing the anode to produce an anode of electrolytic capacitor, which is then subsequently tested for its electrical properties. Accordingly, another embodiment of the present invention relates to capacitor anodes formed from oxidized valve metal oxides of the present invention. The anodes can be made of a pulverized form of reduced oxides in a process similar to that used for the manufacture of metal anodes, for example, porous pressed granules with embedded valve metal cables followed by sintering and anodizing. The anodes made from some of the reduced oxygen metal oxides of the present invention, may have a capacitance of about 20,000 or less CV / ga approximately 300,000 CV / g or more and other capacitance ranges may be 62,000 CV / g. about 200,000 CV / g and preferably about 60,000 to 150,000 CV / g. In the formation of the capacitor anodes of the present invention, a sintering temperature can be used which will allow the formation of a capacitor anode having the desired properties. The sintering temperature will be based on the oxide of metal with reduced oxygen used. Preferably, the sintering temperature is from about 1200 ° C to about 1750 ° C and more preferably from about 1200 ° C to about 1400 ° C and even more preferably from about 1250 ° C to about 1350 ° C when the metal oxide of valve with reduced oxygen is a niobium oxide with reduced oxygen. The sintering temperatures, when the valve metal oxide with reduced oxygen is a tantalum oxide with reduced oxygen, it may be the same as for the niobium oxides. The anodes formed from the valve metal oxides of the present invention are preferably formed at a voltage of about 1 volt to about 35 volts, and preferably from about 6 to about 70 volts. Further, when a niobium oxide with reduced oxygen is used, preferably, the formation voltages are from about 6 to about 50 volts, and more preferably from about 10 to about 40 volts. Other higher training voltages may be used. The reduced metal oxide anodes can be prepared by manufacturing a granule with a conductive cable or other connector followed by treatment in an atmosphere of H2 or other suitable atmosphere in the vicinity of a metallic absorbent material, as with the pulverized metal oxides of the present invention, followed by sintering and optional anodization. In this embodiment, the produced anode article can be produced directly, for example, by forming the metal oxide with reduced oxygen and an anode at the same time. The cable connector can be embedded or adhered at any time before anodizing. It is expected that the forming voltages using other metal oxides are similar or approximately the same and may be even higher for valve metal oxides, such as tantalum oxides. Also, anodes formed from the oxidized metal oxides of the present invention preferably have a CD filtration of less than about 5.0 nA / CV. For example, in one embodiment of the present invention, the formed anodes of some reduced oxygen niobium oxides of the present invention have a CD filtration of about 5.0 nA / CV to about 0.50 nA / CV. The present invention also relates to a capacitor according to the present invention having a metal oxide film on the surface of the capacitor. Preferably, when the reduced oxygen valve metal oxide is a reduced oxygen niobium oxide, the film is a niobium pentoxide film. The means for converting the metal powder into capacitor anodes are known to those skilled in the art and said methods, such as those described in US Pat. Nos. 4,805,074.; 5,412,533; 5,211,741, and 5,245,514, and European Patent Applications Nos. 0 634 762 Al and 0 634 761 Al, all of which are incorporated in their entirety by reference to the present invention. The capacitors of the present invention can be used in a variety of end uses such as automotive electronics, cell phones, computers, such as monitors, motherboards, and the like, consumer electronics including televisions, and CRTs, printers / copiers , electricity supplies, modems, computer diaries, computer disks and the like. The present invention will be further elucidated by the following examples, which are intended to be examples of the present invention.

METHODS OF TEST Anode Manufacture: Size-diameter 5.0038 cms. 3.5 Dp powder weight = 341 mg. Sintering the anode 1300 ° C 10 hours 1450 ° C 10 hours 1600 ° C 10 hours 1750 ° C 10 hours Anodization Ef 30V: 30V Ef @ 60 ° C / 0.1% electrolyte H3P04 constant current 20 mA / g Test Filtration / Capacitance CD- ESR: CD 70% Ef / (21VDC) Filtering Test Test voltage charging time 60 seconds 10% H3P04 @ 21 ° C Testing Training - DF 18% H2S04 @ 21 ° C 120 Hz Reform Anodization 50 V Ef: 50V Ef @ 60 ° C / 0.1% Electrolyte H3P04 constant current 20 mA / g Filtration / capacitance test CD-ESR: CD 70% Ef Filtration Test (35 VDC) Test Voltage charging time 60 seconds 10% H3P04 @ 21 ° C Capacitance - Test DF: 18% H2S04 @ 21 ° C 120 Hz Reform anodization 75V Ef 75V Ef @ 60 ° C / 0.1% Electrolytes H3 P04 constant current 20 mA / g Filtration Test / Capacitance CD-ESR: Test Filtration CD 70% Ef (52.5 VDC) Test voltage load time 60 seconds 10% H3P04 @ 21 ° C Test / Capacitance - DF: 18% H2S04 @ 21 ° C 120 Hz The Scott density, oxygen analysis, phosphorus analysis and BET analysis, were determined according to the procedures established in US Patents Nos. 5,011,742; 4,960,471; and 4,964,906 all incorporated in their entirety to the present description as a reference.

EXAMPLES Example 1 Taurine + 10 mesh hydride chips (99.2 gms) with approximately 50 ppm oxygen were mixed with 22 grams of Nb205 and placed on trays Ta. The trays were placed in a vacuum heat treatment furnace and heated to a temperature of 1000 ° C. The H2 gas was admitted in the furnace at a pressure of + 0.21093 kg / cm2. The temperature was further increased to 1240 ° C and maintained for 30 minutes. The temperature was lowered to 1050 ° C, for 6 minutes until all the H2 was swept from the oven. While still maintained at a temperature of 1050 ° C, the argon gas was evacuated from the furnace until a pressure of 5 x 10"4 torr was achieved At this point, 700 mm of argon was allowed back into the chamber and the furnace was cooled to 60 ° C. The material was passivated with several cyclic exposures at progressively higher partial pressures of oxygen before the furnace was removed as follows: The furnace was refilled with argon at 700mm followed by filling After 4 minutes the chamber was evacuated to 10 ~ 2 torr, the chamber was refilled to 600 mm with argon followed by air at one atmosphere and held for 4 minutes. Then the chamber was refilled to 400 mm of argon followed by air at one atmosphere.After 4 minutes, the chamber was evacuated to 10 ~ 2 torr.Then the chamber was refilled to 200 mm of argon followed by air to an atmosphere and sustain Nest for 4 minutes, the chamber was evacuated to 10"2 torr. The chamber was refilled to an atmosphere with air and held for 4 minutes. The chamber was evacuated to 10 ~ 2 torr. The chamber was refilled to an atmosphere with argon and opened to remove the sample. The product of the powder was separated from the metal sorbent of tantalum chips by casting through a 40 mesh screen. The product was tested with the following results: CV / g of sintered granules at a temperature of 1300 ° C for 10 minutes and formed at 35 volts = 81.297 nA / CV (CD filtration) = 5.0 Density of sintered granules = 2.7 g / cc Density Scott = 14.41 g / in3 Chemical Analysis (ppm) H2 = 56 Ti = 25 Fe = 25 Mn = 10 Si = 25 Sn = 5 Ni = 5 Cr = 10 Al = 5 Mo = 25 Mg = 5 Cu = 50 B = 2 Pb = 2 all others < limits Example 2 Samples 1 to 23 are examples that follow steps similar to the previous ones with pulverized Nb20s as indicated in the Table. For most examples, the mesh sizes of the starting input material are set in the table, for example, 60/100 means smaller than 60 mesh, but greater than 100 mesh. In a similar way, the strainer size of some of the metallic absorbers of Ta is given as 14/40. The metallic absorbent materials marked "Ta-hydride chip" are mesh + 40 with no upper limit of particle size. Sample 18 used Nb as metallic absorbent material, (marketed as Nb powder in CPM N200 chips). The metallic absorbent material for sample 18 was a fine granular Nb powder which was not separated from the final product. X-ray diffraction showed that some of the metallic absorbent material remained as Nb, but most of it was converted to NbOi.i and NbO by the process, as was the starting metal oxide material of Nb205. Sample 15 was a granule of Nb20s, compressed to near a solid density, and reacted with H2 in the vicinity of a metallic absorbent material Ta. The process converted the solid oxide granule into a porous metal piece of NbO suboxide. This piece of metal was sintered to form an Nb metal sheet to create an anode and anodized cable connection at 35 volts using similar electrical forming procedures, to those used for powdered metal chunk granules. This sample demonstrates the unique ability of this process to make a piece of metal ready to anodize in a single step, from a starting material of Nb205. The Table shows the high capacitance and low capacity of CD filtering of the anodes made from of the compressed and sintered powders / granules of the present invention. Microphotographs (SEMs) of several samples were taken. These photographs show the porous structure of the niobium oxide with reduced oxygen of the present invention.

In particular, Figure 1 is a photograph of the outer surface of a granule taken at 5,000 X (sample 15). Figure 2 is a photograph of the inside of the same granule taken at 5,000 X. Figures 3 and 4 are photographs of the outer surface of the same granule at 1,000 X. Figure 5 is a photograph of the sample 11 at 2,000 X and the Figures 6 and 7 are photographs taken from sample 4 at 5,000 X. Figure 8 is a photograph taken from sample 3 at 2,000 X and Figure 9 is a photograph from sample 6 at 2,000 X. Finally, Figure 10 is a photograph of sample 6 taken at 3,000 X and Figure 11 is a photograph of sample 9 taken at 2,000 X.

TABLE ** Major 1 and 2 refers to the primary components present in weight • ** Minor 1 and 2 refers to the secondary components present in weight Samples 11 and 12 had the same input material Samples 2 and 3 had the same input material Samples 6 and 7 had the same input material Samples 9 and 10 had the same input material Example 3 Samples from 24 to 28 followed the same procedure as in Examples 1 and 2, except as indicated in the foot of Table 2 and except that the starting metal oxide was Ta205 (from Mitsui) and the metallic absorbent material was a tantalum powder having a high surface area and having a nominal capacitance of approximately 90,000 Cv / g. The starting metal oxide had approximately the same shape and size as the metallic absorbent material. The objective heat treatment was 1100 ° C to 1300 ° C. In this example, the metallic absorbent material became part of the tantalum oxide with reduced oxygen due to the stoichiometric ratio of the materials, which achieved essentially the same final oxide condition. Figure 12 is a photograph of sample 26 in 2000x, Figure 13 is a photograph of sample 27 in 2000x, Figure 14 is a photograph of sample 28 in 2000x. The filtration of CD and capacitance of the tantalum with reduced oxygen was measured after having been formed into anodes by compression and sintering at a temperature of 1200 ° C using 30 volts as the forming voltage. Table 2 Those skilled in the art will appreciate other embodiments of the present invention from consideration of the description and practice of the invention described herein. It is intended that the specification and examples be considered only as examples, the scope and true spirit of the invention being indicated by the following claims.

Claims (43)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following is claimed as property: CLAIMS 1.- A method for reducing at least partially a metal oxide comprising an oxide of valve metal, said method comprising the heat treatment of the valve metal oxide in the presence of a metallic absorbent material and, in an atmosphere which allows the transfer of the oxygen atoms from the starting valve metal oxide to the absorbent material metallic, for a sufficient period of time and temperatures to form a metal oxide with reduced oxygen.
2. 2. - The method according to claim 1, wherein the valve metal oxide is a tantalum oxide.
3. 3. - The method according to claim 1, wherein the valve metal oxide is a tantalum oxide and the metal oxide with reduced oxygen is a tantalum suboxide.
4. 4. The method according to claim 1, wherein the metal oxide with reduced oxygen has a metal to oxygen ratio of 1: less than 2.5.
5. 5. The method according to claim 1, wherein the metal oxide with reduced oxygen has oxygen levels that are lower than the stoichiometric for a completely oxidized metal.
6. 6. - The method according to claim 1, wherein the metal oxide with reduced oxygen has a microporous structure.
7. 1 . - The method according to claim 1, wherein the metal oxide with reduced oxygen has a pore volume of about 50%.
8. 8. - The method according to claim 1, wherein the hydrogen atmosphere is present in an amount of about 10 Torr A to about 2000 Torr.
9. 9. - The method according to claim 1, wherein the metallic absorbent material comprises particles of tantalum hydride.
10. 10. - The method according to claim 2, wherein the metal absorbent material comprises tantalum of capacitor grade.
11. 11. - The method according to claim 1, wherein the metallic absorbent material is 14/40 mesh tantalum hydride particles.
12. 12. - The method according to claim 1, wherein said atmosphere is a hydrogen atmosphere.
13. 13. - The method according to claim 1, wherein said thermal treatment is at a temperature of about 1000 ° C to about 1300 ° C and for a period of time of about 10 to about 90 minutes.
14. The method according to claim 2, wherein the metallic absorbent material is tantalum.
15. 15. - A metal oxide comprising a valve metal oxide having an atomic ratio of metal to oxygen of 1: less than 2.5.
16. 16. - The metal oxide according to claim 15, wherein the ratio is 1: less than 2.0.
17. 17. - The metal oxide according to claim 15, wherein the ratio is 1 less than 1.5.
18. 18. - The metal oxide according to claim 15, wherein the ratio is 1: 0.167 or 2: 2.2.
19. 19. - The metal oxide according to claim 15, wherein the ratio is 1: 1
20. 20. - The metal oxide according to claim 15, wherein the ratio is 1: 0.5
21. 21. - The metal oxide according to claim 15, wherein said valve metal oxide is a tantalum oxide
22. 22. - The metal oxide according to claim 16, wherein said valve metal oxide is a tantalum oxide
23. 23. - The metal oxide according to claim 17, wherein said valve metal oxide is a tantalum oxide.
24. 24. - The metal oxide according to claim 18, wherein said valve metal oxide is a tantalum oxide.
25. 25. - The metal oxide according to claim 19, wherein said valve metal oxide is a tantalum oxide
26. 26. - The metal oxide according to claim 20, wherein said valve metal oxide is a tantalum oxide.
27. 27. - The metal oxide according to claim 15, wherein said valve metal oxide is an aluminum oxide.
28. 28. - The metal oxide according to claim 16, wherein said valve metal oxide is an aluminum oxide.
29. 29. - The metal oxide according to claim 17, wherein said valve metal oxide is an aluminum oxide.
30. 30. - The metal oxide according to claim 18, wherein said valve metal oxide is an aluminum oxide.
31. 31. - The metal oxide according to claim 19, wherein said valve metal oxide is an aluminum oxide.
32. 32. - The metal oxide according to claim 20, wherein said valve metal oxide is an aluminum oxide.
33. 33. - The metal oxide according to claim 15, wherein said valve metal oxide has a porous structure.
34. 34. - The metal oxide according to claim 15, wherein said valve metal oxide has a porous structure having about 0.1 to about 10 micrometer pores.
35. 35. - The metal oxide according to claim 15, wherein said valve metal oxide is formed in an anode of electrolytic capacitor.
36. 36. - The metal oxide according to claim 35, wherein said anode has a CD filtration of about 0.5 to about 5 nA / CV.
37. 37. - The metal oxide according to claim 15, wherein said valve metal oxide comprises nodular shapes, angular chips or combinations thereof.
38. 38. - A capacitor comprising the metal oxide according to claim 15.
39. 39. - The capacitor according to claim 38, wherein said metal oxide is a tantalum oxide.
40. 40. - The capacitor according to claim 38, wherein said metal oxide is an aluminum oxide.
41. 41. A method for the manufacture of a capacitor anode comprising the manufacture of a metal oxide granule and the thermal treatment of the granule in the presence of a metallic absorbent material in an atmosphere which allows the transfer of oxygen atoms from the oxide of starting valve metal to the metallic absorbent material for a period of time and temperature sufficient to form an electrode body which comprises a metal oxide with reduced oxygen, and then anodize it to form a capacitor anode, wherein said oxide metal comprises a valve metal oxide.
42. 42. - The method according to claim 41, wherein said metal oxide is an aluminum oxide.
43. 43. - The method according to claim 41, wherein said metal oxide is a tantalum oxide.