Sintering and electrical properties of spinel-type high-entropy ceramics (Co,Mn,Fe,Zn,Ni,Mg,Al,Cr)3O4 for NTC thermistors

In this study, single-phase high-entropy ceramics (HECs) with the composition (Co,Mn,Fe,Zn,Ni,Mg,Al,Cr) 3 O 4 were successfully synthesized using five different types of spinel raw materials. The resulting material demonstrates excellent performance in the negative temperature coefficient (NTC) thermistor field. X-ray diffraction (XRD) analysis confirmed the structure as a cubic spinel with a single Fd-3m space group. The electron microscope image reveals the growth of ceramic grains with increasing sintering temperature, with a uniform distribution of all elements. After 1800 h of accelerated aging at 150 °C, the Δ R / R 0 value was only 0.41 %, indicating the ceramic's exceptional structural stability. X-ray photoelectron spectroscopy(XPS) analysis reveals that electrical conductivity are mainly governed by electron hopping between Mn 3+ and Mn 4+ ions in the octahedral sublattice sites. Impedance spectroscopy further shows that grain boundary resistance is the dominant contributor to the total resistance. This study provides new insights into the synthesis of single-phase HECs materials and proposes strategies to enhance material stability for future applications.