Yttria-alumina fibers

A method of making a continuous ceramic oxide fiber, said method comprising the steps of

• 1) providing a stable, spinnable aqueous-based mixture comprising
• a) a solution comprising an alumina precursor salt dissolved in water, wherein said alumina precursor salt is represented by Al(OH).sub.3-X (D).sub.x, wherein x is a number in the range from about 0.5 to about 2.0 and D is a counterion selected from the group consisting of chloride, nitrate, carboxylate, and combinations thereof;
• and
• b) a colloidal yttria precursor dispersion,
• wherein said alumina precursor salt and said colloidal yttria precursor dispersion are each present in an amount sufficient to provide, after step (3), said ceramic oxide fiber having an Y.sub.2 O.sub.3 content in the range from 28.5 to 90.7 percent by weight and an Al.sub.2 O.sub.3 content in the range from 71.5 to 9.3 percent by weight, the sum of the total Y.sub.2 O.sub.3 content and the total Al.sub.2 O.sub.3 content being at least 80.0 percent by weight, based on the total oxide content of the fiber;
• 2) forming said aqueous-based mixture into a green continuous fiber;
• and
• 3) heat-treating said green continuous fiber to a temperature and for a time sufficient to provide a continuous ceramic oxide fiber comprising Al, Y, and O, wherein said fiber comprises at least one of amorphous regions and polycrystalline regions, wherein said fiber has a Y.sub.2 O.sub.3 content in the range from 28.5 to 90.7 percent by weight and a total Al.sub.2 O.sub.3 content in the range from 71.5 to 9.3 percent by weight, and wherein the sum of said Y.sub.2 O.sub.3 content and said Al.sub.2 O.sub.3 content is at least 80.0 percent by weight, based on the total oxide content of the fiber.