Investigation on Temperature-Dependent Electrical Transport Behavior of Cobalt Ferrite (CoFe2O4) for Thermistor Applications

Abstract

This paper discusses the temperature and frequency-dependent dielectric and electrical transport properties of cobalt ferrite (CoFe2O4) and its suitability for thermistor applications. The material is prepared through a high-temperature solid-state reaction route. The formation of the materials is checked by using an X-ray diffraction. Microstructure study is done through SEM analysis. Analysis of dielectric data shows a thermally activated relaxation process occuring in the material within the studied frequency range. Analysis of complex impedance (Nyquist) plots at different temperatures reveal the contribution of grain to the overall electrical response of the compound. The variation of dc conductivity with temperature shows the NTCR behavior of the material. Looking into the strong dependence of resistivity on temperature, the thermistor parameters are evaluated using the grain resistance at different temperatures, which suggest the possible application for thermistor-based devices as well as a temperature sensor. The temperature-dependent ac conductivity (σ ac) fits well with Jonscher’s universal power law. The activation energy calculated from the temperature-dependent spectroscopic plots of impedance and conductivity suggests the charge carriers involved in deciding transport properties.