Insights on Structural, Mechanical and Thermal Properties of High-Entropy Perovskite Oxide (Ca0.2Sr0.2Ba0.2La0.2Pb0.2)TiO3 from First-Principles Calculations

High-entropy perovskite oxides attract considerable attention due to their outstanding properties and extensive applications. In this work, the lattice distortion and the mechanical, thermal and electronic structure properties of high-entropy (Ca0.2Sr0.2Ba0.2La0.2Pb0.2)TiO3 (CSBLPT) are investigated through first-principles calculations. The results suggest that the influence of O atoms on lattice distortion is predominant, and the effect of overall A-site atoms plays a distinctly greater role than that of the B-site atoms. The mechanical results show that the high-entropy CSBLPT has a lower Young’s modulus and higher fracture toughness than ternary SrTiO3. The Debye temperature also indirectly indicates that the thermal expansion coefficient of the studied high-entropy perovskite is greater than that of SrTiO3. As for thermal conductivity, the obtained result of CSBLPT is also appreciably lower than that of SrTiO3, and the lowest thermal conductivity is along the [100] direction. The Fermi level of high-entropy CSBLPT is transferred to the conduction band, exhibiting a degenerate n-type semiconductor behavior with metallic-like characteristics, and the Bader charge values are also related to the local lattice distortion, which may cause differences in thermomechanical properties between high-entropy CSBLPT and SrTiO3. Above all, high-entropy CSBLPT is a preferable TBC material with excellent performance under working conditions compared to SrTiO3.