Two types of rare earth tantalite oxides, Sm3Ce7Ta2O23.5 and Gd3Ce7Ta2O23.5, were synthesised using a high-temperature sintering technique. The phase-structures, micro-morphologies, element compositions, thermal conductivities, and thermal expansion performances were investigated. The final conclusions show that these two ceramics are approximately composed of 2RETa0.5Ce2.5O8.25 and RETaCe2O7. The relative densities are above 90%, and the interfaces between grains are clear. Owing to the relatively high total atomic weights, complicated element...
