Thermal-physical performances of novel pyrochlore-type Ca3Ln3Ce7Ta2O26.5(Ln = Nd and Dy) oxides

To identify candidates for thermal barrier coatings, two complicated oxides, Ca(3)Nd(3)Ce(7)Ta(2)O(26.5 )and Ca3Dy3Ce7Ta2O2.65, were prepared via a high-temperature sintering method. The lattice-type and thermal physical properties of these two oxides were studied. The obtained products have a single pyrochlore-type lattice. Because of the high atomic weights, complex element compositions, and complicate lattice structures, the thermal conductivities of the obtained products are lower than that of the yttria-stabilized zirconia (YSZ). The thermal conductivity of Ca3Dy3Ce7Ta2O26.5 is lower than that of Ca3Nd3Ce7Ta2O26.5. The coefficients of thermal expansion for Ca(3)Ln(3)Ce(7)Ta(2)O(26.5) (Ln = Dy and Nd) oxides at 1473 K are approximately 11.92 x 10(-6)/K and 12.1 x 10(-6)/K, respectively. The thermal conductivities and expansion coefficients of these two oxides meet the demands for thermal barrier coatings.