Metal oxides are used as Thermal Barrier Coatings (TBCs) in gas turbines to protect metal alloy components from degradation at the extreme temperatures at which these turbines are operated. The current industry standard, 7%Yttria-stablized Zirconia, becomes structurally compromised as temperatures approach 1300 °C, motivating the search for alternative TBC systems. Herein, the Yttria-Tantala Zirconia system is investigated as a potential TBC, via synthesis of oxide powders. Phases present in the resulting powders are analyzed using X-Ray Diffraction, and Scanning Electron Microscopy. An isothermal section of the ternary system’s phase diagram at 1250 °C, currently unexplored, is investigated in order to better understand phase equilibria in the system. Understanding of phase equilibria will allow for evaluation of the system’s potential as an effective TBC for use in the aerospace and powergeneration industries.