Functional metal oxides and methods of making same
AssigneeThe Johns Hopkins University
InventorsWilliam A. Phelan, Tanya Berry, Mekhola Sinha, Tyrel Matthew McQueen
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Abstract
Metal oxides and method for forming the method oxides are provided. The disclosed functional metal oxides are single crystalline or polycrystalline metal oxides, such as, for example, SrVO3, and have dimensions, phase purity, and crystalline quality previously unachievable. The disclosed methods include a combination of a gas atmosphere, vacuum sintering, and laser-based directional solidification of a seed rod in contact with a feed rod that is scalable for production quantities.
Claims16
A method of making a metal oxide material comprising
- positioning a seed rod comprising an isostatically pressed metal oxide powder within a heating zone;
- heating an end of the seed rod to form a melt portion at the end of the seed rod;
- contacting the melt portion of the seed rod with an end of a feed rod in the heating zone, wherein the feed rod comprises an isostatically pressed metal oxide powder, and wherein a metal oxide of the seed rod is the same as a metal oxide of the feed rod;
- forming a molten zone comprising the melt portion of the end of the seed rod and a melt portion of the end of the feed rod;
- and
- moving the seed rod and feed rod together through the heating zone at a translation rate that allows solidification of a portion of the molten zone to form a single crystalline metal oxide capable of thermionic emission and extension of the molten zone to a portion of the feed rod adjacent to the melt portion;
- wherein the heating zone comprises a forming gas mixture of argon:
- hydrogen in a ratio of 95%:5%;
- and
- wherein the seed rod and the feed rod comprise AMO3, wherein A is Ca, Sr, Ba, or a combination thereof, and Mis V, Nb, Ta, Mo, or a combination thereof.
A method of making a metal oxide material comprising
- positioning a seed rod comprising an isostatically pressed metal oxide powder within a heating zone;
- heating an end of the seed rod to form a melt portion at the end of the seed rod;
- contacting the melt portion of the seed rod with an end of a feed rod in the heating zone, wherein the feed rod comprises an isostatically pressed metal oxide powder, and wherein a metal oxide of the seed rod is the same as a metal oxide of the feed rod;
- forming a molten zone comprising the melt portion of the end of the seed rod and a melt portion of the end of the feed rod;
- and
- moving the seed rod and feed rod together through the heating zone at a translation rate that allows solidification of a portion of the molten zone to form a single crystalline metal oxide capable of thermionic emission and extension of the molten zone to a portion of the feed rod adjacent to the melt portion;
- and wherein:
- the seed rod or the feed rod comprise Sr2V2O7 and SrVO3.
Dependencies are inferred from the claim text.