Structural and thermal-mechanical properties of Ln3Ta5O15 (Ln = Ce, Pr, Nd, Sm, Eu, Gd, Tb) for thermal barrier coatings

In this paper, first-principles calculations are carried out on investigating the structural, elastic, mechanical, and thermophysical properties of rare-earth tantalates Ln3Ta5O15 (Ln = Ce, Pr, Nd, Sm, Eu, Gd, Tb) compounds. The results show that tetragonal Ln3Ta5O15 compounds exhibit low thermal conductivity (1.143–1.225 W/m∙K for Cahill’s model and 1.013–1.102 W/m∙K for Clarke’s model), indicating their prominent thermal insulation performance. In addition, the ceramics exhibit compatible coefficients of thermal expansion (1.924–2.101 × 10−5 K−1) and high melting points (1887.39–2024.10 K). Furthermore, their excellent mechanical properties (HV: 10.472–11.813 GPa, KIC: 1.761–1.958 MPa∙m1/2), good thermal shock resistance and superior damage tolerance are comparable to those of YSZ, making them potential applications as new thermal barrier coatings.