Phase stability and thermophysical properties of neodymium cerium composite oxide

Nd2CexO3+2x (x = 2.25, 2.5, 2.75, 3.0) were synthesized by solid-state reaction, and their phase stabilities and thermophysical properties were investigated. The X-ray diffraction (XRD) results indicated that Nd2CexO3+2x with fluorite structure were stable after long-term annealing at 1673 K. They have higher thermal expansion coefficients (TECs) than yttria-stabilized zirconia (YSZ) which is the typical thermal barrier coating (TBC) material, especially the thermal expansion as a function of temperature is parallel to that of the nickel-based superalloy. This behavior is beneficial to the reduction of the residual stresses induced by the thermal expansion mismatch at the interface between the ceramic layer and bond coat. The reduction of sintering abilities of Nd2CexO3+2x coatings was achieved by the addition of excess CeO2 into the starting powders to make a nearly stoichiometric Nd2Ce2O7 coating. Nd2CexO3+2x can be explored as a new candidate material for TBCs.