PROCESS FOR PRODUCING CRYSTALLINE TANTALUM OXIDE PARTICLES

Abstract

The present invention is in the field of processes for the production of tantalum oxide particles. In particular the present invention relates to a process for producing crystalline tantalum oxide nanoparticles comprising heating a water-free solution containing (a) a tantalum alkoxide, (b) an acid, and (c) a solvent.

Claims

1. A process for producing crystalline tantalum oxide nanoparticles comprising heating a water-free solution containing (a) a tantalum alkoxide, (b) an acid, and (c) a solvent,

2. The process according to claim 1, wherein the solvent is a hydrocarbon.

3. The process according to claim 1, wherein the solvent is a C.sub.12 to C.sub.24 hydrocarbon.

4. The process according to claim 1, wherein the acid is a carboxylic acid.

5. The process according to claim 4, wherein the carboxylic acid is a C.sub.8 to C.sub.22 carboxylic acid.

6. The process according to claim 1, wherein a molar ratio of the acid to the tantalum alkoxide is from 5 to 30.

7. The process according to claim 1, wherein a concentration of the tantalum alkoxide in the water-free solution is from 10 to 200 mmol/l.

8. The process according to claim 1, wherein the tantalum alkoxide is tantalum(,)-methoxide, tantalum(V)-ethoxide, or tantalum(V)-n-butoxicle.

9. The process according to claim 1, wherein a molar ratio of the acid to the tantalum alkoxide is from 2.5 to 50.

10. The process according to claim 1, wherein the water-free solution is heated to a temperature of from 120 to 400 C.

11. The process according to claim 1 wherein the water-free solution further contains an amine.

12. The process according to claim 11, wherein the amine is a monoalkylamine.

13. A method for producing a superconductor, comprising: using a crystalline particle comprising a tantalum oxide and having a weight average diameter of 1 to 20 nm, as a pinning center.

14. The method according to claim 13, wherein the superconductor, contains REBa.sub.2Cu.sub.3O.sub.7-x, wherein RE stands for rare earth and x is from 0.01 to 0.3.

Description

EXAMPLES

Example 1

[0064] 4.3 mL oleic acid and 9 mL octadecene were degassed under vacuum at 120 C. for one hour.

[0065] Then, the temperature was raised to 180 C. and 0.25 mL tantalum ethoxide was rapidly injected in the mixture. The reaction mixture was further heated to 260 C. and kept at that temperature for 15 minutes, after which the sample was allowed to cool down to room temperature. The particles were precipitated and redissolved in chloroform. This purification procedure was repeated two times. Transmission electron microscopy (TEM) analysis depicted in FIG. 1 shows that the particles are uniform in size (5 nm diameter) and from the high resolution images it can be concluded that the particles are crystalline. FIG. 2 shows an X-ray diffractogram of the sample obtained, wherein the peaks are assigned to the crystal planes of tantalum oxide.