NTC thermo-sensitive ceramics with low B value and high resistance at low temperature in Li-doped Mn0.6Ni0.9Co1.5O4 system

Abstract

In this paper, negative temperature coefficient (NTC) thermistors Mn0.6Ni0.9Co1.5−xLixO4 (x = 0, 0.05, 0.1, 0.2) used for low temperature were synthesized by the co-precipitation method. XRD indicates the formation of single-phase LiMn2O4 spinel. SEM shows that the incorporation of lithium reduces the sintering activity and increases the grain size 2 to 6.8 μm. XPS presents that the remarkable change of the contents of Mn3+/Mn4+ and Co2+/Co3+ confirms the conduction mechanism of the variable ion transition. The relationship between the electrical resistivity and the temperature shows that the doping of Li benefits the Mn0.6Ni0.9Co1.5O4 material to increase the resistance value and reduce the material constant B value. This is significant because of traditional thermal-sensitive materials with high resistance and high B, while low-B high resistance materials have been scarcely reported. The materials are expected to be used for deep sea thermal detector.