Electronic structure and thermal properties of Sm <sup>3+</sup> ‐doped La <sub>2</sub> Zr <sub>2</sub> O <sub>7</sub> : First‐principles calculations and experimental study
Yiming Li, Xuanyu Meng, Qian Chen, Jiatong Zhu, Jie Xu, Michael J. Reece, Feng Gao
Abstract
Abstract By applying the first‐principles calculation, the electronic structure, mechanical and thermal properties of Sm 3+ ‐doped La 2 Zr 2 O 7 were investigated, and experiments were carried out to verify the theoretical results. As the Sm 3+ doping rate increases, the lattice parameters decrease while the theoretical density increases. The doping of Sm 3+ promotes the transformation from pyrochlore structure to defective fluorite structure. The Young's modulus of pure La 2 Zr 2 O 7 shows obvious anisotropy, while it tends to be isotropy with the doping of Sm 3+ . 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 Sm 3+ doping rate of La 2 Zr 2 O 7 is 50%. LaSmZr 2 O 7 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 LaSmZr 2 O 7 has good mechanical and thermal properties, which provides new ideas for the selection of thermal barrier coating materials.