High-entropy pyrochlores with low thermal conductivity for thermal barrier coating materials

High-entropy pyrochlore-type structures based on rare-earth zirconates are successfully produced by conventional solid-state reaction method. Six rare-earth oxides (La 2 O 3 , Nd 2 O 3 , Sm 2 O 3 , Eu 2 O 3 , Gd 2 O 3 , and Y 2 O 3 ) and ZrO 2 are used as the raw powders. Five out of the six rare-earth oxides with equimolar ratio and ZrO 2 are mixed and sintered at different temperatures for investigating the reaction process. The results demonstrate that the high-entropy pyrochlores (5RE 1/5 ) 2 Zr 2 O 7 have been formed after heated at 1000°C. The (5RE 1/5 ) 2 Zr 2 O 7 are highly sintering resistant and possess excellent thermal stability. The thermal conductivities of the (5RE 1/5 ) 2 Zr 2 O 7 high-entropy ceramics are below 1 W·m –1 ·K –1 in the temperature range of 300–1200°C. The (5RE 1/5 ) 2 Zr 2 O 7 can be potential thermal barrier coating materials.