Formation and properties of Ca2+ substituted (Ce0.2Zr0.2Ti0.2Sn0.2Hf0.2)O2 high-entropy ceramics

Abstract

Five equimolar multicomponent oxides were synthesized by replacing one of five cations in (Ce0.2Zr0.2Ti0.2Sn0.2Hf0.2)O2 with Ca2+. The results reveal that except for the one in which Ce4+ replaced by Ca2+, the other four components can form single-phase high-entropy fluorite oxides (HEFOs) at different temperatures, which indicates that Ce4+ is very important for the formation of single-phase HEFOs. The sintering behavior, lattice parameter and properties containing density, porosity, flexural strength and thermal conductivity of the four single-phase HEFOs were investigated. With the change of substituted ions, grain size, relative density, flexural strength and thermal conductivity of the materials vary greatly, which are correlated to the size disorder and mass disorder of these materials. The results of this paper provide a reference for the composition designing and performance tailoring of equimolar HEFOs.