AU2005234714B2

AU2005234714B2 - Production of ultra fine transition metal powders

Info

Publication number: AU2005234714B2
Application number: AU2005234714A
Authority: AU
Inventors: Kamran M. Khozan; Sergiy Kovtin; Victor Emmanuel Nanthakumar; Dmitri S. Terekhov
Original assignee: CVMR Corp
Current assignee: CVMR Corp
Priority date: 2005-03-09
Filing date: 2005-11-21
Publication date: 2007-05-24
Anticipated expiration: 2025-11-21
Also published as: CN1830607A; AU2005234714A1; CA2500077A1; ZA200509386B

Description

P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Invention Title: Production of ultra fine transition metal powders The following statement is a full description of this invention, including the best method of performing it known to us: 1648 PRODUCTION OF ULTRA FINE TRANSITION METAL POWDERS FIELD OF THE INVENTION This invention relates to a process for the production of ultra fine transition metal S powders, particularly, vanadium, niobium and tantalum powders by the pyrolysis of transition 0 metal complexes in a high boiling point inert solvent, such as a hydrocarbon or higher alkyl alcohol.

PUBLICATIONS

1. "Highly Reduced Organometallic Complexes of Vanadium, Niobium, Tantalum and Chromium", a thesis submitted to the Faculty of the Graduate School of the University of Minnesota by Marie Kathleen Pomije, (September 1995).

2. Inorg. Chem. (1998), 37 6518-6527, Barybim et al 3. Inorganica Chemica Acta. (1998), 269, 58-62 Barybin 4. Chem. Euro. J. (1995), 1, No. 8 Ellis et al 0 5. Inorg. Chem. (1983), 22, 1865-1870 Calderazzo et al SUMMARY OF THE INVENTION The present invention provides for the production of ultra fine transition metal complexes by the pyrolysis of the metal complex. Preferably, the heating of the metal complex is effected in a suitable inert solvent such as, for example, a hydrocarbon, alkyl alcohol, ether, diglyme, ester at an effective temperature for a sufficient period of time.

Examples of suitable metal complexes comprise carbonyl and trifluorophosphine groups wherein the metal has a valence of 0 or such as [Et 4 N][Ta(PF 3 6 [Et 4 N][Nb(PF 3 6 and [Et 4

N][V(PF

3 6 Accordingly, in one aspect, the invention provides a method of preparing ultra fine metal powder of a transition metal selected from the group consisting of the third, fourth and fifth groups of the Periodic Table of the Elements, said method comprising pyrolizing a complex metal compound of said metal, wherein said metal is in a valence state selected from 0 and 1, in an inert solvent at an effective temperature to produce said ultra fine powder, and M removing said powder from said inert solvent.

Preferably, said hydrocarbon is of the formula CnH 2 n+ 2 wherein n is selected from 12 to Preferably, said alkanol is of the formula CnH 2 n+l OH wherein n is selected from 10 to t We have found that the metal powder has a mean particle size of less than 10 microns, C 0 preferably 1 to 5 microns and more preferably, less than 1 micron.

The process of the invention is applicable to suitable metal complexes of the first, second and third transition metal series of the Periodic Table of the Elements. Most preferred are the Group VB elements, namely, vanadium, niobium and tantalum.

In a further aspect, the invention provides ultra fine metal powders produced by the processes as hereinabove defined.

In a further aspect, the invention provides for the use of the ultra fine metal powders according to the invention, particularly the use wherein the metal is tantalum in cell phones.

The metal complexes of use in the practise of the invention may be made by the reduction of salts of the metals in solution in the presence of ligand reagents, such as carbon 0 monoxide, trifluorophosphine and naphthalene.

A two-step reductive trifluorophosphination to produce [Et 4 N][Ta(PF 3 6 [Et 4 N][Nb(PF 3 6 [Et4N] [V(PF 3 6 has been described DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS In order that the invention may be better understood, preferred embodiments will now be described.

EXAMPLES

EXAMPLE 1 Cobalt carbonyl, Co 2 (CO)8, (10g) was dissolved in warm toluene (20 mL) and the solution was slowly added to paraffin oil at 250 OC. The red solution immediately darkened and become black. Carbon monoxide gas and toluene vapours were evolved and removed. 0 S After the cobalt carbonyl had decomposed, the paraffin oil was cooled, filtered and the a residue washed with hexane and dried to provide sub-micron cobalt powder (3.4 g, 99 EXAMPLE 2 SManganese carbonyl, Mn(CO) 6 (5 g) was dissolved in warm acetone (10 mL) and added to n-hexadecanol and heated to 250 C. Carbon monoxide gas and acetone vapours S were evolved. The solution became black and after the manganese carbonyl had decomposed S0 the n-hexadecane was cooled, filtered and the residue was washed with hexane and dried to provide sub-micron manganese powder (1.2 g, 99 EXAMPLE 3 HTa(PF 3 6 (5 g) was dispersed in paraffin oil and heated to 360 C. Immediate decomposition of the Ta complex was observed with evolution of hydrogen and PF 3 After the complex was decomposed, the paraffin oil was cooled, filtered and the residue washed with n-hexane and dried. Sub-micron tantalum powder (1.25 g, 99 was obtained.

0 EXAMPLE 4 [Et 4 N] [Ta(PF 3 6 1, (100g), was dissolved in acetone (50mL), added to boiling ndecanol (100mL) and stirred for 20 minutes. The black solution was filtered, and the collected powder was washed with acetone and air dried to given sub-micron tantalum powder (22g).

Although this disclosure has described and illustrated certain preferred embodiments of the invention, it is to be understood that the invention is not restricted to those particular embodiments. Rather, the invention includes all embodiments which are functional or mechanical equivalence of the specific embodiments and features that have been described and illustrated.

1^ As used herein, the term "comprise" and variations of the term, such as "comprising", "comprises" and "comprised", are not intended to exclude other additives, components, integers or steps.

SReference to any prior art in the specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in Australia or any other jurisdiction or that this prior art could reasonably be expected to be ascertained, understood and regarded as relevant by a person skilled in the Sart.

Claims

1. A method of preparing ultra fine metal powder of a transition metal selected from the group consisting of the third, fourth and fifth groups of the Periodic Table of the Elements, said method comprising pyrolizing a complex metal compound of said metal wherein said metal is in a valence state selected from 0 and 1, in an inert solvent at an effective temperature to produce said ultra fine powder, and removing said powder from said inert solvent.

2. A method as defined in claim 1 wherein said solvent is selected from the group (Ni consisting of a long chain alkyl hydrocarbon and a long chain alkyl alkanol. S0 3. A method as defined in claim 2 wherein said hydrocarbon is of the formula CnH 2 2 wherein n is selected from 12 to

4. A method as defined in claim 2 wherein said alkanol is of the formula CH 2 1 OH wherein n is selected from 10 to A method as defined in any one of claims 1 to 4 wherein said effective temperature is greater than 300'C.

6. A method as defined in any one of claims 1 to 5 wherein said powder has a mean particle size of less than 10 microns.

7. A method as defined in claim 6 wherein said mean particle size is selected from 1 to microns. 0 8. A method as defined in any one of claims 1 to 7 wherein said metal is selected from the Group VB metals selected from V, Nb and Ta.

9. An ultra fine metal powder when made by a method as defined in any one of claims 1 to 8. An ultra fine metal powder as claimed in claim 9 having a mean particle size of less than 10 microns.

11. Use of an ultra fine metal powder as defined in any one of claims 1 to 10 in cell phones.

12. A method of preparing ultra fine metal powder having the steps substantially as hereinabove described.