Abstract: Sm₂O₃ partly doped La₂Ce₂O₇ ceramic materials for thermal barrier coatings were prepared by high temperature solid-state reaction using La₂O₃, CeO₂ and Sm₂O₃ as raw materials. Their chemical formula is (Sm_xLa_1-x)₂Ce₂O₇. The phase composition of the samples was studied by X-ray diffraction (XRD). The doping ratio, firing temperature and firing time were investigated by an XRD pattern contrast analysis of the samples made in different conditions. It is found that the sample with fluorite structure has been prepared, and it can maintain its phase structure when the doping molar ratio Sm:La is 1:2 or 1:3. As the doping molar ratio Sm:La is 1:2 at the firing temperature of 1550℃ for 10 h, the prepared (Sm_0.33La_0.67)₂Ce₂O₇ has a good phase stability at 1600℃. This material can be potentially used as a new material for ceramic thermal barrier coatings.