Design and synthesis of thermistor materials with high aging stability: Multicomponent equiatomic Mn-Co-Ni-Al-Zn-O ceramics

High entropy oxide (HEO) is a new class of ceramic materials. It is well known for its unique microstructure and remarkable property. In this work, a multicomponent equiatomic Mn–Co–Ni–Al–Zn–O oxide was synthesized using a solid-state reaction route based on entropic engineering. The phase composition of the samples was investigated, which showed the formation of two main phases: Fm 3‾ m for the rock salt phase and Fd 3‾ m for the spinel phase. In addition, the electrical behavior of Mn–Co–Ni–Al–Zn–O ceramic was investigated. The 5-cation ceramic exhibits extremely high aging stability with a resistance drift of 0.27% under accelerated aging conditions at 125 °C for 500 h. In contrast, the aging drift rate of the 4-cation samples is at approximately 2%. It was found that the design of multicomponent equiatomic oxide brings a significant benefit to the aging stability of the material. Thus, it provides an opportunity to improve the aging stability.