Electrical and aging properties of Mn2-xNi0.7Cu0.3ZnxO4 NTC ceramic thermistors for low-resistance applications

The electrical properties and aging phenomenon of negative temperature coefficient (NTC) Cu-based Mn2-xNi0.7Cu0.3ZnxO4 (x = 0 – 0.4) spinel ceramics for low-resistance applications were reported. Effect of composition, sintering process, and annealing treatment on the aging phenomenon of the ceramics was investigated. X-ray photoelectron spectroscopy (XPS) analysis showed that the suppressed aging was attributed to a decreased distribution of the unstable Cu+ cations in the ceramics. With the increase of Zn-substitution concentration, a significant increase in electrical resistivity and a slight increase in thermal constant were observed. Through composition tailoring and appropriate annealing, Mn2-xNi0.7Cu0.3ZnxO4 NTC thermistors with high performance: a relatively low resistivity (~ dozens of Ω cm), a high-level thermal constant B (> 3000 K) and high stability (aging coefficient < 2.0%) were obtained. The results indicate that the spinel structure and electrical properties can be adjusted in a desired range, depending on composition and processing conditions.