CA2018346A1 - Niobium oxide powder (nb o ) and a process for its preparation - Google Patents
Niobium oxide powder (nb o ) and a process for its preparationInfo
- Publication number
- CA2018346A1 CA2018346A1 CA002018346A CA2018346A CA2018346A1 CA 2018346 A1 CA2018346 A1 CA 2018346A1 CA 002018346 A CA002018346 A CA 002018346A CA 2018346 A CA2018346 A CA 2018346A CA 2018346 A1 CA2018346 A1 CA 2018346A1
- Authority
- CA
- Canada
- Prior art keywords
- weight
- niobium oxide
- nb2o5
- ppm
- process according
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G33/00—Compounds of niobium
-
- 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
-
- 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
- C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
-
- 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
- C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/12—Surface area
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
- Compositions Of Oxide Ceramics (AREA)
Abstract
Title: Niobium oxide powder (Nb2O5) and a process for its preparation ABSTRACT OF THE DISCLOSURE
Niobium oxide powders in non-agglomerated form with a narrow particle size distribution range, high specific surface area, high purity and 2-20 ppm Fe and 2-30 ppm Ni usable in carbide preparation, ferro alloy melting and as a raw material for optical glasses and electro-ceramic and electro-optical products. The powders are made by precipitation from fluoride solution, filtering, washing, annealing and milling. The washing is carried out to an extent that annealing losses are 10-50 % by weight, the calcining is at 600°C-1000°C and the calci-ned product is finley ground.
Niobium oxide powders in non-agglomerated form with a narrow particle size distribution range, high specific surface area, high purity and 2-20 ppm Fe and 2-30 ppm Ni usable in carbide preparation, ferro alloy melting and as a raw material for optical glasses and electro-ceramic and electro-optical products. The powders are made by precipitation from fluoride solution, filtering, washing, annealing and milling. The washing is carried out to an extent that annealing losses are 10-50 % by weight, the calcining is at 600°C-1000°C and the calci-ned product is finley ground.
Description
201~33~6 Title; Niobium oxide powder (Nb2O5) and a process for its preparation _ _ _ . . . . .. .. . . _ _ .
BACK~ROUND OF THE INVENTION
This invention relates to an improved niobium oxide powder (Nb2O5) which consist~ to an extent of more than 90 % of the T-phase, has a fluorine value of under 1000 ppm, passes through a 45 micron sieve to an extent of over 99,9 % by weight, has a specific surface area according to Brunauer Emmett Tellertest/BET (ASTM
D 3037/~1) of more than 3,5 m~/g and has an Nb2O5 con-tent of over 99,8 % by weight, not taking into account the losses on annealing, and to a process for the pre-paration of this niobium oxide powder.
Ta2O and Nb2O5 are normally decomposed by means of an acid mixture of HF and H2SO4. The fluoro complexes of the two elements, dissolved in aqueous mineral acids, are extracted with organic solvents, preferably methyl isobutyl ketone (MIBK~. The niobium fluoro acid i~ then reextracted from the organic phase and the hydrated niobium oxide is precipitated from the aqueous strip solution with ammoniacal water, This procedure is followed by filtrat~on of the solid and drying and calcining at temperatures above about 1000C (Ullmanns "Enzyklopadie der techni~che Chemie, 4th Edition, 1979, Volume 17).
~5 20183~6 The oxides prepared by this process are used for the preparation of carbides for hard metals, the melting of ferro alloys, and as raw material for optical glasses and for electroceramic and electro-optical products.
Nb205 has for some time now been used to an increasing extent in ceramic condensers, especially in so-called relaxor-perovskites (See, t.: Swartz and Shrout, "Fabrication of Perovskite Lead Magnesium Niobate", Mat. Res. Bull., Volume 17, pages 1245-1250, 1982).
The presently available Nb205 powders are, in various respects, suitable only to a limited extent for the last mentioned purpose. It is an obgect of the present invention to provide suitable powders.
SUMMARY OF THE INVENTION
It has now been found that the requirements are fulfilled by niobium oxide powders which are present as fine powders in an non-agglomerated form with a narrow particle size distribution and uniformity of the partic-les. An additional characteristic of these powders is that they have as large a specific surface area (BET
surface) as possible and a very h;gh degree of purity.
X~83~i The invention compri 5 es a nobium oxide (Nb205) powder which a) consists to an extent of over 90 % by weight of T-phase, b) has a fluorine value of under 1000 ppm, c) passes through a 45 micron siev0 to an extent of over 99,9 % by weight, and d) has a specific surface area according to BET
(ASTM D 3037/81~ of more than 3,5 n~/g and e) an Nb205 content of over 99,8 % by weight, not taking into account the 10s5 on annealing and f) contains from 2 to 20 ppm of Fe an from 2 to 30 ppm of Ni.
An Nb205 powder of this type which has the following particle size distribution according to a Sedigraph 5000 D (ASTM B 761-86~ is particularly preferred:
90 % by weight, under 2,5 micro~s 50 % by weight, under 1,0 microns, preferably from 0,5 to 0,7 microns, 30 % by weight, 0,6 microns.
This invention further relates to a process for the preparation of the acid niobium oxide powders. The process consists of a combination of known process steps in which hydrated niobium oxide is procipitated with ammoniacal water from a fluoride-containing solution and then filtered, wa~hed, annealed and milled, in which process Z018~46 a) washing to the filter cake obtained after fil-trat;on is followed by dry;ng to such an extent that the dry product has a loss on annealing of from 10 to 50 % we;ght, preferably from 20 to 30 X by we;ght, b) the dry product is calcined at temperatures from 600C to 1000C and c~ the calcined product thus obtained is finley ground, :
In the process according to the in~ention, calci-nation is preferably carr;ed out at temperatures from 800 to 900C, Th;s calcination may be carried out in known apparatus Calcination in an rotary tube furnace has proved to be particularly economical and should be carried out o~er a res;dence time of at least one hour, preferably not less than 2 hours, Particularly good results are obtained from the process according to the ;nv-ntion if the filter cake ;s washed unt;l ;t contains less than 0,5 X by weight of fluorine DETAILED DESCUPTION OF PREFERRED EMBODIMENTS
The ;n~ent;on ict d-scr;bed in dotail bolow with th- aid of a non-l;miting illu-trating a preferr-d embodiment of pratice, .
- ' , X0~83~6 EXAMPLE
BACK~ROUND OF THE INVENTION
This invention relates to an improved niobium oxide powder (Nb2O5) which consist~ to an extent of more than 90 % of the T-phase, has a fluorine value of under 1000 ppm, passes through a 45 micron sieve to an extent of over 99,9 % by weight, has a specific surface area according to Brunauer Emmett Tellertest/BET (ASTM
D 3037/~1) of more than 3,5 m~/g and has an Nb2O5 con-tent of over 99,8 % by weight, not taking into account the losses on annealing, and to a process for the pre-paration of this niobium oxide powder.
Ta2O and Nb2O5 are normally decomposed by means of an acid mixture of HF and H2SO4. The fluoro complexes of the two elements, dissolved in aqueous mineral acids, are extracted with organic solvents, preferably methyl isobutyl ketone (MIBK~. The niobium fluoro acid i~ then reextracted from the organic phase and the hydrated niobium oxide is precipitated from the aqueous strip solution with ammoniacal water, This procedure is followed by filtrat~on of the solid and drying and calcining at temperatures above about 1000C (Ullmanns "Enzyklopadie der techni~che Chemie, 4th Edition, 1979, Volume 17).
~5 20183~6 The oxides prepared by this process are used for the preparation of carbides for hard metals, the melting of ferro alloys, and as raw material for optical glasses and for electroceramic and electro-optical products.
Nb205 has for some time now been used to an increasing extent in ceramic condensers, especially in so-called relaxor-perovskites (See, t.: Swartz and Shrout, "Fabrication of Perovskite Lead Magnesium Niobate", Mat. Res. Bull., Volume 17, pages 1245-1250, 1982).
The presently available Nb205 powders are, in various respects, suitable only to a limited extent for the last mentioned purpose. It is an obgect of the present invention to provide suitable powders.
SUMMARY OF THE INVENTION
It has now been found that the requirements are fulfilled by niobium oxide powders which are present as fine powders in an non-agglomerated form with a narrow particle size distribution and uniformity of the partic-les. An additional characteristic of these powders is that they have as large a specific surface area (BET
surface) as possible and a very h;gh degree of purity.
X~83~i The invention compri 5 es a nobium oxide (Nb205) powder which a) consists to an extent of over 90 % by weight of T-phase, b) has a fluorine value of under 1000 ppm, c) passes through a 45 micron siev0 to an extent of over 99,9 % by weight, and d) has a specific surface area according to BET
(ASTM D 3037/81~ of more than 3,5 n~/g and e) an Nb205 content of over 99,8 % by weight, not taking into account the 10s5 on annealing and f) contains from 2 to 20 ppm of Fe an from 2 to 30 ppm of Ni.
An Nb205 powder of this type which has the following particle size distribution according to a Sedigraph 5000 D (ASTM B 761-86~ is particularly preferred:
90 % by weight, under 2,5 micro~s 50 % by weight, under 1,0 microns, preferably from 0,5 to 0,7 microns, 30 % by weight, 0,6 microns.
This invention further relates to a process for the preparation of the acid niobium oxide powders. The process consists of a combination of known process steps in which hydrated niobium oxide is procipitated with ammoniacal water from a fluoride-containing solution and then filtered, wa~hed, annealed and milled, in which process Z018~46 a) washing to the filter cake obtained after fil-trat;on is followed by dry;ng to such an extent that the dry product has a loss on annealing of from 10 to 50 % we;ght, preferably from 20 to 30 X by we;ght, b) the dry product is calcined at temperatures from 600C to 1000C and c~ the calcined product thus obtained is finley ground, :
In the process according to the in~ention, calci-nation is preferably carr;ed out at temperatures from 800 to 900C, Th;s calcination may be carried out in known apparatus Calcination in an rotary tube furnace has proved to be particularly economical and should be carried out o~er a res;dence time of at least one hour, preferably not less than 2 hours, Particularly good results are obtained from the process according to the ;nv-ntion if the filter cake ;s washed unt;l ;t contains less than 0,5 X by weight of fluorine DETAILED DESCUPTION OF PREFERRED EMBODIMENTS
The ;n~ent;on ict d-scr;bed in dotail bolow with th- aid of a non-l;miting illu-trating a preferr-d embodiment of pratice, .
- ' , X0~83~6 EXAMPLE
2,5 cubic meters of niobium fluoride solution obtained from re-extraction and containing about 120 g of Nb205 per litre are added to 7 cubic meters of a 3 X aqueous ammonia solution, and ammoniacal water at a concen-tration of 25 X is added to this mixtrue until a pH of 9 is obtained. The precipitated hydrated oxide is sepa-rated off through a plate filter and neutralized by washing with 7 cubic meters of 3 X ammoniacal water and 6 cubic meters of demin-ralized water. Tho fluorine con-tent of the filter cake ist then less than 0,5 % by weight. The filter cake i6 dried. The loss on annealing of a sample crude product is then worked up in a rotary tube furnace at 900C and a residence time of 2 hours.
The annealed oxide is subsequently size reduced in a jet mill.
Ph~sical and chemical analysis Specific sufrace (BET): 4,26 n~/g Particle spectrum (Sedigraph 5000 D): 90 X under 1 micron 50 X under 0,56 micron 30 % under 0,48 micron Sie~e analysis: 99,9 % under 45 micron Proportion of T-phase: over 90 X by weight ~5 20~334~
Charac~eristic impuri~ies:
Fluorine : 360 ppm Calcium : 8 ppm Chromium : under 2 ppm Iron : ~ ppm Nickel : 4 ppm Tantalum : under 12 ppm
The annealed oxide is subsequently size reduced in a jet mill.
Ph~sical and chemical analysis Specific sufrace (BET): 4,26 n~/g Particle spectrum (Sedigraph 5000 D): 90 X under 1 micron 50 X under 0,56 micron 30 % under 0,48 micron Sie~e analysis: 99,9 % under 45 micron Proportion of T-phase: over 90 X by weight ~5 20~334~
Charac~eristic impuri~ies:
Fluorine : 360 ppm Calcium : 8 ppm Chromium : under 2 ppm Iron : ~ ppm Nickel : 4 ppm Tantalum : under 12 ppm
Claims (10)
1. Niobum oxide (Nb2O5) powder which a) comprises mor than 90 % by of T-phase, b) has a fluorine value of comprise less than 1000 pppm, c) passes through a 45 micron sieve to an extent of more than 99,9 X by weight and d) has a specific surface area according to BET
(ASTM D 3037/81) of more than 3,5 m2/g and e) an Nb2O5 content of more than 99,8 % by weigh, not taking into account the loss on annea-ling, and further characterised in that it contains from
(ASTM D 3037/81) of more than 3,5 m2/g and e) an Nb2O5 content of more than 99,8 % by weigh, not taking into account the loss on annea-ling, and further characterised in that it contains from
2 to 20 ppm of Fe and from 2 to 30 ppm of Ni.
2. Niobium oxide powder in accordance with claim 1 characterised in that it has a particle size distribution according to a Sedigraph 5000 D (ASTM
B 761-86) of 90 % by weight less than 2,5 microns 50 % by weight less than 1,0 microns 30 % weight less than 0,6 microns.
2. Niobium oxide powder in accordance with claim 1 characterised in that it has a particle size distribution according to a Sedigraph 5000 D (ASTM
B 761-86) of 90 % by weight less than 2,5 microns 50 % by weight less than 1,0 microns 30 % weight less than 0,6 microns.
3. Niobium oxide powder in accordance with claim 2 wherein at least 50 X by weight thereof is from 0,5 to 0,7 micron size sarge.
4. A process for the preparation of Nb2O5 powder as set forth in either of claims 1 or 2 by the pre-cipitation of hydrated niobium oxide with ammonical water from a solution containing fluoride followed by filtration, washing, annealing and grinding, in which a) washing of the filter cake obtained from filtration is followed by drying to such an extent that the dry product has a loss on annealing of from 10 to 50 % by weight, preferably from 20 to 30 % by weight, b) the dry product is calcined at temperatures from 600°C to 1000°C and c) the calcined product thus obtained is finley ground.
5. A process according to claim 4, wherein calcination is carried out at temperatures from 800°C to 900° C.
6. A process according to either of claims 4 or 5, wherein calcination is carried out in a rotary tube furnace.
7. A process according to Claim 6, wherein in calci-nation is carried out with a residence time of at least one hour.
8. A process according to claim 7 wherein the resi-dence time is at least two hours.
9. A process for the preparatio of Nb2O5 powder accor-ding to any of claims 4 to 8, wherein the filter cake is washed until it contains less than 0,5 X
by weight of fluorine.
by weight of fluorine.
10. A process according to eithers of Claims 4 or 5, wherein fine grinding of the calcined material is carried out in a je mill.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3918691A DE3918691A1 (en) | 1989-06-08 | 1989-06-08 | NIOBOXIDE POWDER (NB (DOWN ARROW) 2 (DOWN ARROW) O (DOWN ARROW) 5 (DOWN ARROW)) AND METHOD FOR THE PRODUCTION THEREOF |
| DEP3918691.1 | 1989-06-08 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2018346A1 true CA2018346A1 (en) | 1990-12-08 |
Family
ID=6382335
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002018346A Abandoned CA2018346A1 (en) | 1989-06-08 | 1990-06-06 | Niobium oxide powder (nb o ) and a process for its preparation |
Country Status (11)
| Country | Link |
|---|---|
| EP (1) | EP0402687B1 (en) |
| JP (1) | JPH0323222A (en) |
| KR (1) | KR0140871B1 (en) |
| CN (1) | CN1025669C (en) |
| AT (1) | ATE101104T1 (en) |
| AU (1) | AU630967B2 (en) |
| BR (1) | BR9002693A (en) |
| CA (1) | CA2018346A1 (en) |
| DD (1) | DD297949A5 (en) |
| DE (2) | DE3918691A1 (en) |
| ZA (1) | ZA904388B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7066979B2 (en) | 2002-03-12 | 2006-06-27 | H. C. Starck Gmbh | Valve metal powders and process for producing them |
| US7099143B1 (en) | 2005-05-24 | 2006-08-29 | Avx Corporation | Wet electrolytic capacitors |
| WO2022036427A1 (en) * | 2020-08-17 | 2022-02-24 | Fras-Le S.A. | Preparation of niobium nanoparticles, use and method for obtaining same |
| EP4105180A4 (en) * | 2020-02-14 | 2023-08-30 | Mitsui Mining & Smelting Co., Ltd | Niobic acid aqueous solution |
Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4030707A1 (en) * | 1990-09-28 | 1992-04-02 | Starck Hermann C Fa | METHOD FOR THE PRODUCTION OF LOW FLUORIDE TANTALY / NIOB OXIDE HYDRODATES OR OXIDES |
| US6338832B1 (en) | 1995-10-12 | 2002-01-15 | Cabot Corporation | Process for producing niobium and tantalum compounds |
| US6416730B1 (en) † | 1998-09-16 | 2002-07-09 | Cabot Corporation | Methods to partially reduce a niobium metal oxide oxygen reduced niobium oxides |
| RU2246376C2 (en) | 2000-03-01 | 2005-02-20 | Кабот Корпорейшн | Nitrated valve metals and methods for producing such metals |
| JP4996016B2 (en) * | 2001-06-01 | 2012-08-08 | 三井金属鉱業株式会社 | Niobium oxide slurry, niobium oxide powder and production method thereof |
| US20040062709A1 (en) * | 2001-12-27 | 2004-04-01 | Kenji Higashi | Powder of tantalum oxide or niobium oxide, and method for production thereof |
| JP4202195B2 (en) * | 2003-06-10 | 2008-12-24 | 三井金属鉱業株式会社 | Tantalum hydroxide, niobium hydroxide, tantalum oxide, niobium oxide, and production methods thereof |
| CN103253708B (en) * | 2013-05-08 | 2014-11-05 | 北京工业大学 | Solvothermal preparation method of niobium pentoxide nanowire by use of acetic acid |
| CN107055613B (en) * | 2017-02-27 | 2018-10-30 | 湖南工业大学 | A kind of no substrate niobium pentoxide nano chip arrays negative material and its preparation method and application |
| JP7290921B2 (en) * | 2018-07-06 | 2023-06-14 | 太陽誘電株式会社 | Piezoelectric ceramic composition, manufacturing method thereof, piezoelectric ceramic, piezoelectric element, and piezoelectric vibration device |
| US11058883B2 (en) * | 2019-02-15 | 2021-07-13 | Medtronic, Inc. | Feedthrough assembly |
| CN110386623B (en) * | 2019-07-04 | 2022-04-19 | 江西海协稀有金属材料有限公司 | Method for preparing high-purity niobium oxide by filtering niobium ceramic membrane |
| GB2616009B (en) | 2022-02-23 | 2024-05-01 | Echion Tech Limited | Electrode and method of manufacture |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3640679A (en) * | 1969-02-06 | 1972-02-08 | Molybdenum Corp | Process for recovery of columbium |
| JPS4930354A (en) * | 1972-07-17 | 1974-03-18 | ||
| JPS5110197A (en) * | 1974-07-16 | 1976-01-27 | Ishihara Sangyo Kaisha | Suisankaniobu mataha suisankatantaruno seizohoho |
| DK449074A (en) * | 1974-08-22 | 1976-02-23 | Atomenergikommissionen | PROCEDURE FOR EXTRACTING TANTALS AND / OR NIOB IN FREE OR BASED FORM FROM TANTAL AND NIOB CONTAINING SOLUTIONS |
| DE3428788C2 (en) * | 1983-08-11 | 1986-07-10 | Günter J. 8510 Fürth Bauer | Process for the continuous production of low-fluoride tantalum or niobium pentoxides |
| DD250706A1 (en) * | 1986-07-01 | 1987-10-21 | Mansfeld Kombinat W Pieck Veb | PROCESS FOR THE PREPARATION OF FLUORIDE TANTAL OR NITROPOXIDE OXIDE |
-
1989
- 1989-06-08 DE DE3918691A patent/DE3918691A1/en active Granted
-
1990
- 1990-05-26 EP EP90110025A patent/EP0402687B1/en not_active Expired - Lifetime
- 1990-05-26 AT AT90110025T patent/ATE101104T1/en not_active IP Right Cessation
- 1990-05-26 DE DE90110025T patent/DE59004470D1/en not_active Expired - Fee Related
- 1990-06-06 CA CA002018346A patent/CA2018346A1/en not_active Abandoned
- 1990-06-06 DD DD90341374A patent/DD297949A5/en not_active IP Right Cessation
- 1990-06-07 BR BR909002693A patent/BR9002693A/en not_active IP Right Cessation
- 1990-06-07 ZA ZA904388A patent/ZA904388B/en unknown
- 1990-06-07 JP JP2147510A patent/JPH0323222A/en active Pending
- 1990-06-07 KR KR1019900008310A patent/KR0140871B1/en not_active IP Right Cessation
- 1990-06-08 AU AU57043/90A patent/AU630967B2/en not_active Ceased
- 1990-06-08 CN CN90104138A patent/CN1025669C/en not_active Expired - Lifetime
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7066979B2 (en) | 2002-03-12 | 2006-06-27 | H. C. Starck Gmbh | Valve metal powders and process for producing them |
| US7485257B2 (en) | 2002-03-12 | 2009-02-03 | H.C. Starck Gmbh | Valve metal powders |
| US7099143B1 (en) | 2005-05-24 | 2006-08-29 | Avx Corporation | Wet electrolytic capacitors |
| US7456073B2 (en) | 2005-05-24 | 2008-11-25 | Avx Corporation | Wet electrolytic capacitors |
| EP4105180A4 (en) * | 2020-02-14 | 2023-08-30 | Mitsui Mining & Smelting Co., Ltd | Niobic acid aqueous solution |
| WO2022036427A1 (en) * | 2020-08-17 | 2022-02-24 | Fras-Le S.A. | Preparation of niobium nanoparticles, use and method for obtaining same |
Also Published As
| Publication number | Publication date |
|---|---|
| DE59004470D1 (en) | 1994-03-17 |
| BR9002693A (en) | 1991-08-20 |
| JPH0323222A (en) | 1991-01-31 |
| ZA904388B (en) | 1991-03-27 |
| CN1047842A (en) | 1990-12-19 |
| AU5704390A (en) | 1990-12-13 |
| AU630967B2 (en) | 1992-11-12 |
| CN1025669C (en) | 1994-08-17 |
| DE3918691A1 (en) | 1990-12-13 |
| KR0140871B1 (en) | 1998-06-01 |
| EP0402687A1 (en) | 1990-12-19 |
| KR910000537A (en) | 1991-01-29 |
| EP0402687B1 (en) | 1994-02-02 |
| DE3918691C2 (en) | 1991-07-04 |
| ATE101104T1 (en) | 1994-02-15 |
| DD297949A5 (en) | 1992-01-30 |
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