US 12,247,317 B2
Functional metal oxides and methods of making same
William A. Phelan, Baltimore, MD (US); Tanya Berry, Baltimore, MD (US); Mekhola Sinha, Baltimore, MD (US); and Tyrel Matthew McQueen, Baltimore, MD (US)
Assigned to THE JOHNS HOPKINS UNIVERSITY, Baltimore, MD (US)
Appl. No. 17/639,805
Filed by THE JOHNS HOPKINS UNIVERSITY, Baltimore, MD (US)
PCT Filed Sep. 4, 2020, PCT No. PCT/US2020/049490
§ 371(c)(1), (2) Date Mar. 2, 2022,
PCT Pub. No. WO2021/046410, PCT Pub. Date Mar. 11, 2021.
Claims priority of provisional application 62/895,854, filed on Sep. 4, 2019.
Prior Publication US 2022/0325439 A1, Oct. 13, 2022
Int. Cl. C30B 13/16 (2006.01); C30B 29/30 (2006.01); H01J 1/144 (2006.01)
CPC C30B 29/30 (2013.01) [C30B 13/16 (2013.01); H01J 1/144 (2013.01); H01J 2201/2817 (2013.01)] 16 Claims
OG exemplary drawing
 
1. 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.