Potential thermal barrier coating material: High entropy ceramic (Ca0.5Sr0.5)(5RE)2O4 with enhanced thermophysical properties

Single-phase high entropy ceramic (Ca0.5Sr0.5)(5RE)2O4 (RE = Y, Sm, Gd, Dy, Yb) (CSHO) with anti-spinel structure was synthesized via solid-state reaction method. The CSHO has good high-temperature phase stability at 1600 °C for 10–50 h. In addition, the CSHO ceramics exhibit much lower thermal conductivity and higher thermal expansion coefficient than that of SrY2O4, towing to the intensified phonon-point defect scattering and the enhanced anharmonic vibrations of the lattice. The thermal conductivity of CSHO is 1.48–1.81 W∙m−1 K−1 (25–1500 °C), and the thermal expansion coefficient is 11.5–12.0 × 10−6 K−1 (1000–1500 °C). The obtained results suggest that CSHO has the potential to become the next-generation thermal barrier coating materials.