Effects of sintering temperature on ac conductivity, permittivity, and permeability of manganese doped cobalt ferrite nanoparticles

Abstract

This paper reports on the effects of magnetic and electric properties of a non-stoichiometric composition of cobalt ferrite nanoparticles doped with manganese content at the weight percent 0.25. Its toroid and disc-shaped samples were sintered at two different temperatures 750 °C and 1050 °C. The studied results show the dependence of the permittivity and permeability on the microstructural features, particularly crystallite/grain size that change with the sintering temperature. The anomalous behavior of ac conductivity is marked outside a hump region with a decreased sintering temperature. A rightward shift of the characteristic frequency in the absorption of electric modulus is observed with the increased sintering temperature. Similarly, a rightward shift of the resonance frequency in the spectra of the imaginary part of the magnetic modulus is marked with the increased sintering temperature. The higher magnitude of the imaginary part of the electric modulus at the characteristic frequency is expected to dissipate as eddy current loss. Similarly, the higher magnitude of the imaginary part of the magnetic modulus at the resonance frequency is assumed to dissipate as a residual loss. Both of them are selectable by the sintering temperature. This behavior may make this material suitable to be used in thermoelectric and thermomagnetic sensors/switches.

Keywords

• Conductivity
• Permittivity
• Permeability
• Modulus
• Eddy current loss
• Residual loss