Characterization of temperature sensitivity of V-modified CuFe 2 O 4 ceramics for NTC thermistors

Copper ferrite ceramics, CuFe 2− x V x O 4 ( x = 0, 0.015, 0.03, 0.04 and 0.05), were prepared by a wet-chemical synthesis method followed by the traditional ceramic sintering process. The influence of V-ion content on phase component, ionic valence states, microstructures and electrical properties of the ceramics was investigated. The X-ray diffraction analysis shows that all the ceramics have cubic structure of spinel CuFe 2 O 4 phase. All ceramics show the typical characteristic of negative temperature coefficient (NTC) of resistivity in the measurement temperature region between 25 and 250 °C. The temperature-sensitivity parameters of the ceramics can be adjusted from 3319 to 4920 K by changing the content of V-ions. The analysis of complex impedance revealed that both grain effect and grain-boundary effect contributed to the electrical properties of the ceramics. The possible conduction mechanism was proposed to be a thermal-activated polaron hopping conduction.