Preparation and electrical conductivity of (Zr, Hf, Pr, Y, La) O high entropy fluorite oxides

A series of compositionally complex fluorite oxides (CCFOs) were prepared by ball milling the mixture of ZrO2, HfO2, Y2O3, La2O3, and Pr6O11 followed by conventional solid-state sintering. Both XRD and TG-DSC results demonstrated that single-phase (Zr0.2Hf0.2Pr0.2Y0.2La0.2)O2-δ was formed at 1400 °C. Elements in bulk ceramic were uniformly distributed without evident accumulation according to SEM-EDS pictures. TEM results revealed that polycrystalline ceramic powder was assignable to cubic Fm-3m fluorite structure. The electrical conductivity (σ) was measured via EIS technology and activation energy (Ea) of CCFOs was calculated in Arrhenius plots. In the temperature range of 300-750 °C, CCFOs preserved the same conduction mechanism and (Zr0.1667Hf0.1667Pr0.1667Y0.25La0.25)O2-δ possessed higher σ and lower Ea than other high entropy fluorite oxides which is related to the incorporation of Pr element or the connection of cation-Vo complex.