3.2.3. Effect of Fe co-doped with cobalt in Ni0.7Mn1.8−xCo0.5FexO4
Owing to the fact that Fe ion has some specialities, such as changeable valency Fe2+ and Fe3+, the flexible occupation of A-site and B-site in spinel structure, Fe ion has complicated influence on electrical properties of electroceramics [8]. Introduction of Fe3+ ion into the Ni–Mn–Co–O system may arouse an interesting change in electrical properties of NTC thermistors. Some reports were published with Fe substituting the Co in Ni–Mn–Co–O systems [12] and [13]. In this work, Fe is substituted for Mn by keeping the Ni:Co ratio constant.