Enhanced Structural and Aging Stability in Cation-Disordered Spinel-Type Entropy-Stabilized Oxides for Thermistors

Entropy-stabilized ceramics (ESCs) are an emerging group of solid solutions that contain five or more elemental species. These materials possess great compositional flexibility and are of vital technical and scientific significance in many applications, covering catalysis, lithium-ion batteries, thermal barrier coatings, super-ionic conductors, etc. Here, a novel class of (Co0.2Mn0.2Fe0.2Zn0.2Ni0.2)3O4 ESCs was designed and synthesized using the solid-state reaction technique for thermistor applications following the entropy-stabilized design strategy. Moreover, as a critical parameter in the formation of entropy stability, the influences of sintering temperature on structural and electrical behavior were systematically investigated at 1150–1225 °C. Our results indicate that each of the synthesized samples exhibits a single spinel structure in the space group Fd-3m (227), and all five species are uniformly distributed on the nanometer scale, indicating entropy stabilization. Also, the fabricated ESCs manifest excellent negative temperature coefficient (NTC) characteristics and outstanding aging stability (ΔR/R0 = 0.19%). Such ESCs will be an attractive candidate material for thermistor applications and provide new insights into the further development of advanced electronic ceramics.