Synthesis of rare earth element-containing alumina nanowires
View Patent ↗Rare earth element(s) doped alumina nanowires are formed by a thermal evaporation method in which vapor from aluminum powder and vapor from a rare earth element compound (such as an halide) are reacted in an oxygen-containing inert gas stream to form alumina which deposits as alumina nanowires and as a rare earth element and oxygen-containing material that deposits with and/or on the alumina nanowires. Where the RE-doped alumina nanowires are to be used as catalyst supports, a catalyst material, such as platinum, may be deposited as small particles on the nanowires.
1. Alpha-alumina nanowires containing one or more rare earth elements, or one or more oxides of one or more rare earth elements, on or within the nanowires, the alpha-alumina nanowires further comprising nanoparticles of one or more catalytic materials supported on the nanowires.
2. Alpha-alumina nanowires as recited in claim 1 containing one or more oxides of one or more rare earth elements on or within the nanowires.
3. Alpha-alumina nanowires as recited in claim 1 containing at least one of cerium and lanthanum.
4. Alpha-alumina nanowires as recited in claim 1 containing an oxide of at least one of cerium and lanthanum.
5. Alpha-alumina nanowires as recited in claim 1 in which the proportion, by weight, of aluminum to rare earth element is in the range of about 30:1 to about 450:1.
6. A method of making rare earth element containing alumina wires having diameters in the range of about ten to about 300 nanometers, the method comprising:
heating a mixture of aluminum powder and particles of at least one compound of at least one rare earth element in a stream of oxygen-containing inert gas to produce aluminum vapor and vapor containing the rare earth element such that oxygen reacts with the vapor to form alumina nanowires containing the rare earth element or an oxide of the rare earth element.
7. A method of making rare earth element containing alumina wires as recited in claim 6 in which a stream of the oxygen-containing inert gas is flowed over the mixture and rare earth-containing alumina wires are deposited on a substrate at the location of the mixture or downstream from it.
8. A method of making rare earth element containing alumina wires as recited in claim 6 in which the rare earth element is at least one of cerium and lanthanum.
9. A method of making rare earth element containing alumina wires as recited in claim 6 in which the mixture comprises aluminum and a rare earth halide.
10. A method of making rare earth element containing alumina wires as recited in claim 6 in which the mixture comprises aluminum and a rare earth iodide.
11. A method of making rare earth element containing alumina wires as recited in claim 6 in which the aluminum and rare earth containing mixture is heated to about 1300° C.
12. A method of making rare earth element containing alumina wires as recited in claim 6 in which oxygen in oxygen-containing argon is reacted with the aluminum vapor and the vapor from the rare earth compound.
13. Alpha-alumina nanowires as recited in claim 1 containing one or more oxides of one or more rare earth elements on or within the nanowires and further comprising nanoparticles of one or more catalytic materials supported on the nanowires.
14. Alpha-alumina nanowires as recited in claim 13 in which the catalytic material is a platinum group metal.
15. A method of making rare earth element containing alumina wires as recited in claim 6 in which nanoparticles of one or more catalytic materials are deposited on the formed alumina nanowires.