Role of mixed entropy in sintering of manganite-based perovskite oxides: Faster densification with delayed grain growth

Abstract

High entropy perovskite oxides (HEPOs) have garnered significant attention due to their superior performance compared to conventional perovskite oxides. However, there is a limited understanding of the sintering behavior of HEPOs. This study aims to obtain a mechanistic understanding of how the sintering of the manganite-based perovskite oxides varies with the mixed entropy. Based on systematic sintering experiments, detailed microstructural characterization, and molecular dynamics simulations, we found that the densification process of manganite-based perovskite oxides with increasing mixed entropies follows a similar pattern to conventional perovskite oxides. The mixed entropy significantly influences the final and middle stages of densification but has negligible effects in the initial stage. More importantly, the densification becomes easier and faster with the increased mixed entropy, while the grain growth is delayed to the higher relative density and the corresponding activation energy for grain growth is also significantly enhanced. Consequently, this creates a more ideal situation for achieving denser materials with smaller grain sizes during sintering, shedding light on rational optimization of the sintering and resulting properties of high entropy perovskite oxide.