Abstract
High-entropy oxides (HEOs) are widely researched as potential materials for thermal barrier coatings (TBCs). However, the relatively low thermal expansion coefficient (TEC) of those materials severely restricts their practical application. In order to improve the poor thermal expansion property and further reduce the thermal conductivity, high-entropy (La0.2Nd0.2Sm0.2Eu0.2Gd0.2)2Ce2O7 is designed and synthesized in this work. The as-prepared multicomponent material is formed in a simple disordered fluorite structure due to the high-entropy stabilization effect. Notably, it exhibits a much higher TEC of approximately 12.0 × 10−6 K−1 compared with those of other high-entropy oxides reported in the field of TBCs. Besides, it presents prominent thermal insulation behavior with a low intrinsic thermal conductivity of 0.92 W·m−1·K−1 at 1400 °C, which can be explained by the existence of high concentration oxygen vacancies and highly disordered arrangement of multicomponent cations in the unique high-entropy configuration. Through high-temperature in-situ X-ray diffraction (XRD) measurement, this material shows excellent phase stability up to 1400 °C. Benefiting from the solid solution strengthening effect, it shows a higher hardness of 8.72 GPa than the corresponding single component compounds. The superior thermo-physical performance above enables (La0.2Nd0.2Sm0.2Eu0.2Gd0.2)2Ce2O7 a promising TBC material.
Highlights
Inspired by the remarkable research developments inJ Adv Ceram 2022, 11(4): 615–628 entropy nitrides [5], high-entropy borides [6,7], highentropy sulfides [8], and high-entropy silicides [9,10].Currently, there is no specific definition for HECs, while Xiang et al [11] defined them as multi-principalcomponent solid solutions in which the near-equiatomic cations share one or more Wyckoff sites simultaneously.Among the various high-entropy materials, High-entropy oxides (HEOs) have aroused extensive research interest
In the measurement of thermal diffusivities (λ), the sample was cut into a size of φ 10 mm × 3 mm disc and evaporated with gold and graphite on both sides to protect the sample from laser reflection of ion beam and weaken the high-temperature heat radiation
An optimal pre-sintering temperature is extremely crucial for the preparation of dense ceramic bulk
Summary
J Adv Ceram 2022, 11(4): 615–628 entropy nitrides [5], high-entropy borides [6,7], highentropy sulfides [8], and high-entropy silicides [9,10]. HECs are successfully confirmed to be a promising candidate for TBCs with lower thermal conductivity than their corresponding constituent materials Such excellent thermal insulation property largely originates from the cocktail effect in high-entropy compound. The research on thermal contraction behavior of cerium oxide-based high-entropy oxides is still a lack of deep study To address these problems, a new highentropy ceramic (La0.2Nd0.2Sm0.2Eu0.2Gd0.2)2Ce2O7 with fluorite structure is designed and successfully synthesized in this work. As TBC material, (La0.2Nd0.2Sm0.2Eu0.2Gd0.2)2Ce2O7 manifests obvious improvement compared with that of other single component rare-earth cerates reported in the literature Such prominent thermo-physical properties largely attribute to the cocktail effect of high-entropy material, which combine the properties of the constituent components and eventually exceed them. This work further enriches the research content for the family of high-entropy materials
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
