(Ba0.5Sr0.5)(Ti0.25Zr0.25Hf0.25Sn0.25)O3: A novel thermal barrier material with low thermal conductivity and excellent resistance to CMAS corrosion

High entropy ceramics are considered as promising materials for thermal barrier coatings due to phonon scattering caused by lattice distortion. In this study, perovskite high-entropy ceramics (Ba 0.5 Sr 0.5 )(Ti 0.25 Zr 0.25 Hf 0.25 Sn 0.25 )O 3 (BSTZHS) were successfully prepared by dramatically increasing the conformational entropy of ceramics with complex crystal structures. The results showed that the sample exhibits a single-phase perovskite crystal structure with a dense surface, each element of the sample was uniformly distributed. Moreover, the thermal conductivity of (Ba 0.5 Sr 0.5 )(Ti 0.25 Zr 0.25 Hf 0.25 Sn 0.25 )O 3 decreased significantly compared to SrZrO 3 and BaZrO 3 (the minimum thermal conductivity is 1.37 W/(m·K) at 273–1273 K). This study also identified descriptors for predicting the decrease in thermal conductivity of perovskite high-entropy ceramics. As well, the samples not only exhibit outstanding mechanical properties (Young’s modulus E = 255.7 ± 8.6 GPa、flexural strength F b = 142.1 ± 4.8 MPa), but also good resistance to CMAS corrosion. Various results support that (Ba 0.5 Sr 0.5 )(Ti 0.25 Zr 0.25 Hf 0.25 Sn 0.25 )O 3 is potential to be used for thermal barrier coatings.