Electronic structure and thermal properties of Sm³⁺-doped La₂Zr₂O₇: First-principles calculations and experimental study

By applying the first-principles calculation, the electronic structure, mechanical and thermal properties of Sm³⁺-doped La₂Zr₂O₇ were investigated, and experiments were carried out to verify the theoretical results. As the Sm³⁺ doping rate increases, the lattice parameters decrease while the theoretical density increases. The doping of Sm³⁺ promotes the transformation from pyrochlore structure to defective fluorite structure. The Young's modulus of pure La₂Zr₂O₇ shows obvious anisotropy, while it tends to be isotropy with the doping of Sm³⁺. The calculated theoretical hardness is positively correlated with the doping rate, yet due to the solid solution strengthening effect, the materials with doping rate of 50% get the highest hardness. Based on the calculations and experiments, the optimal Sm³⁺ doping rate of La₂Zr₂O₇ is 50%. LaSmZr₂O₇ has hardness of 11.35 GPa, the thermal conductivity of 1.35 W/(m·K) at 1173 K, and the thermal expansion coefficient of 10.12 × 10⁻⁶/K at 1173 K. The above results indicate that LaSmZr₂O₇ has good mechanical and thermal properties, which provides new ideas for the selection of thermal barrier coating materials.