Abstract
The influence of Ca content on the morphology and related electrical properties of Co1.5−xCaxMn1.2Ni0.3O4 (x = 0, 0.2, 0.4, 0.8) ceramics was studied. Appropriate addition of Ca will reduce the grain size, but when the content of Ca is 0.4, the holes will appear on the surface. As the Ca content of Co1.5−xCaxMn1.2Ni0.3O4 increases from 0 to 0.8, the temperature-dependent resistivity (ρ25) decreases from 1291.5 to 180.8 Ω cm, and the value of B25/50 decreases from 3860 to 3077 K. This is because the addition of Ca ions promotes the valence conversion of Mn3+ ions to Mn4+ ions, reduces the ratio of Mn3+/Mn4+, and thereby reduces the resistivity. The results show that when the Ca content is 0.4, the material has small grain size, low resistivity, and B value. It can be used as a NTC thermistor potential candidate materials in the temperature range of 223 K to 323 K.
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