Abstract: A composition comprising an yttria-rare earth-doped zirconium oxide is provided that has a tetragonal structure and a formula: YaLnbCexZr1-a-b-xO2-? where Ln is a mixture of rare earth elements; 0.01?a?0.051; 0.01?b?0.051 such that Y and each rare earth element is included in the composition in substantially equal molar amounts; 0.05?(a+b)?0.07; 0?x?0.051; and 0???0.05. Methods of forming a coating that includes this composition, along with the resulting coated components, are also provided.

Abstract: A composition is provided of a rare earth-doped zirconium oxide having a tetragonal structure and having a formula: YaLnbTaxNbzZr1-a-b-x-zO2-? where Ln is a rare earth element or a mixture of rare earth elements; 0?a?0.06; 0.06?b?0.12; 0?x?0.1; 0?z?0.1; 0.08?(x+z)?0.1; 0.16?(a+b+x+z)?0.22; and 0.01???0.05. Methods of forming a coating with this composition, along with the coated components, are also provided.

Abstract: A composition comprising a rare earth-doped zirconium/hafnium oxide is provided that has a defect-fluorite structure or a pyrochlore structure. The rare earth-doped zirconium/hafnium oxide has a formula: (Ln1aLn2aLn3aLn4aLn5b)2M2O7 where each of Ln1, Ln2, Ln3, Ln4, and Ln5 is a different rare earth element such that Ln1 and M have a first atomic radius ratio that is 1.35 to 1.45, Ln2 and M have a second atomic radius ratio that is 1.35 to 1.45, Ln3 and M have a third atomic radius ratio that is 1.46 to 1.78, and Ln4 and M have a fourth radius ratio that is 1.46 to 1.78; a is 0.2 or 0.25; b is 0.2 when a is 0.2, and b is 0 when a is 0.25; and M is Zr, Hf, or a mixture thereof. Methods of forming a coating that includes this composition, along with the resulting coated components, are also provided.