Mechanical properties, thermophysical properties and electronic structure of Yb3+ or Ce4+-doped La2Zr2O7-based TBCs

First-principles calculations based on density functional theory were performed to investigate the cohesive energies, elastic modulus, Debye temperatures, thermal conductivities and density of states of La2−xYbxZr2O7, La2Zr2−xCexO7 and La2−xYbxZr2−xCexO7 (x = 0.00, 0.25, 0.50, 0.75, 1.00) ceramics. The results show that doping Yb3+ or Ce4+ into La2Zr2O7 reduces its elastic modulus, thermal conductivity and Debye temperature. Compared with La2−xYbxZr2O7 (x ≠ 0.00), La2Zr2−xCexO7 compounds have better ductility and lower Debye temperature. The Debye temperature values of La2Zr2−xCexO7 (x ≠ 0.00) compounds are in the range of 485.0–511.5 K. Among all components, the fluorite-type La2−xYbxZr2−xCexO7 (x = 0.75, 1.00) compounds exhibit better mechanical and thermophysical properties, and their thermal conductivity values are only 1.213–1.246 W/(m∙K) (1073 K), which are 14.5%–16.7% lower than that of the pure La2Zr2O7. Thus, our findings open an entirely new avenue for TBCs.