For the development of ceramic candidates for thermal barrier coatings, two kinds of new ceramics, Y 3 Ce 7 Ta 2 O 23.5 and Yb 3 Ce 7 Ta 2 O 23.5 , were synthesized by sintering at 1873 K for 10 h. The obtained samples were composed of a single fluorite-type phase, and their relative densities are greater than 90%. Because of phonon scattering caused by the complex lattice, the large number of oxygen vacancies, and substituted atoms, the thermal conductivity is lower than that of 8YSZ. The coefficients of thermal expansion (CTEs) of these two p...
