Methods of metal oxide nanocrystals preparation
Embodiments relate to methods of metal oxide nanocrystals preparation. In embodiments, a metal-organic precursor may be economically synthesized by reacting a metal with an organic acid. The organic acid may include an aliphatic chain longer than three carbon atoms. The metal may be In, Sn, Al, Ga, Zn, Cd, Sb, Bi, Ge, Mn, Ti, Nb, V, Cr, Mo, Fe, Y, Mg, Co, as well as mixtures thereof. Further processing of the metal-organic precursor (e.g. by pyrolysis, hydrolysis, or alcoholysis) produces metal oxide nanocrystals of desired characteristics. An metal-organic precursor of indium tin oxide (ITO) may be synthesized by reacting indium metal and tin metal with an organic acid having an aliphatic chain longer than three carbon atoms (e.g. stearic acid) at a temperature above 200° C. Further processing of the resulting metal-organic precursor yields ITO nanocrystals of regular shape, uniform size, and average diameter ranging of between about 1-500 nm.
1. A method comprising:
forming a first metal-organic precursor by conducting a neat reaction of a first metal with an organic acid at a first temperature at or higher than a reacting point at which the organic acid begins to react with the first metal, wherein the organic acid comprises a carboxylic fatty acid having three or more carbon atoms; and
performing additional processing to convert the first metal-organic precursor to metal oxide nanocrystals, wherein the additional processing comprises hydrolysis following further calcination.
2. A method as in claim 1 wherein the organic acid comprises an aliphatic chain longer than three carbon atoms.
3. A method as in claim 1 wherein the first metal is selected from the group consisting of In, Sn, Al, Ga, Zn, Cd, Sb, Bi, Ge, Mn, Ti, Nb, V, Cr, Mo, Fe, Y, Mg, and Co.
4. A method as in claim 1 wherein the first metal comprises tin.
5. A method as in claim 1 wherein the first metal comprises indium.
6. A method as in claim 1 further comprising forming a second metal-organic precursor from reaction between a second metal and the organic acid.
7. A method as in claim 6 wherein the first metal comprises indium, the second metal comprises tin, and the organic acid comprises an aliphatic chain longer than three carbon atoms.
8. A method as in claim 6 further comprising forming a third metal-organic precursor from reaction between a third metal and the organic acid.
9. A method as in claim 1 wherein the organic acid comprises a fatty acid with an aliphatic chain of more than six carbon atoms.
10. A method as in claim 9 wherein the fatty acid comprises stearic acid.
11. A method comprising:
forming a first metal-organic precursor by conducting a neat reaction of a first metal with an organic acid at a first temperature at or higher than a reacting point at which the organic acid begins to react with the first metal, wherein the organic acid comprises a carboxylic fatty acid having three or more carbon atoms; and
performing additional processing to convert the first metal-organic precursor to metal oxide nanocrystals, wherein the additional processing comprises the addition of alcohol to cause alcoholysis.
12. A method as in claim 1 wherein the nanocrystals have sizes between about 1-500 nm.
13. A method as in claim 1 wherein the first temperature is between about 100-400° C.
14. A method as in claim 1 wherein the neat reaction is performed in a nitrogen atmosphere.
15. A method as in claim 1 wherein the neat reaction is performed at greater than atmospheric pressure.
16. A method as in claim 11 wherein the organic acid comprises an aliphatic chain longer than three carbon atoms.
17. A method as in claim 11 wherein the first metal comprises tin, indium, iron, zinc, gallium, cobalt, or manganese.
18. A method as in claim 11 wherein the nanocrystals have sizes between about 5-300 nm.
19. A method as in claim 11 wherein the first temperature is between about 100-400° C.
20. A method as in claim 11 wherein the neat reaction is performed in a nitrogen atmosphere.