Improvement in the electrical stability of Mn–Ni–Co–O NTC thermistors by substituting Cr2O3 for Co3O4

The as-sintered Mn1.1Ni1.4Co0.5−xCrxO4 (0 ≤ x ≤ 0.35) samples were crystallized in a cubic spinel Mn- and Ni-rich oxides. The substituted Cr led to a significant decrease in the resistivity change of the Mn1.1Ni1.4Co0.5−xCrxO4 negative temperature coefficient (NTC) thermistors after the thermal constraint. This indicates that the Cr-substituted Mn1.1Ni1.4Co0.5−xCrxO4 NTC thermistors have good electrical stability in comparison to the Cr-free Mn1.1Ni1.4Co0.5O4 thermistors. We strongly propose that the Cr substitution is highly desirable for the fabrication of stable high-performance NTC thermistors.