Characterization of temperature sensitivity of V-modified CuFe2O4 ceramics for NTC thermistors
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Copper ferrite ceramics, CuFe2−xVxO4 (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 CuFe2O4 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.
The authors acknowledge the support by the National Natural Science Foundation of China (No. 51767021) and the Jiangxi Yunjia High Tech Co., Ltd. (No. 738010128).