Theoretical investigation of mechanical and thermal properties of RE2Hf2O7 (RE=La, Ce, Pr, Nd, Pm and Sm) pyrochlore oxides

Abstract We applied first-principles calculations to study the relationship between structure and properties (e.g. the thermal conductivity and the elastic stiffness) of the rare-earth pyrochlores with the general formula RE 2 Hf 2 O 7, where RE is La, Ce, Pr, Nd, Pm and Sm. The lattice parameters of these pyrochlores increase with the RE radii increasing in the order from Sm to La. RE 2 Hf 2 O 7 with RE  = Ce, Pr, Nd, Pm and Sm have similar mechanical and thermal properties. However, for mechanical and thermal properties, La 2 Hf 2 O 7 is lower than other pyrochlores. Thermal conductivities of these materials are in the range of 1.38–1.62 W m −1  K −1 which are all lower than the thermal conductivity of yttria stabilized zirconia. Therefore, rare earth hafnate pyrochlores are predicted to promising candidates as thermal barrier coatings.