Facile Synthesis and Temperature Dependent Dielectric Properties of MnFe2O4 Nanoparticles

Manganese ferrite (MnFe2O4) nanoparticles have been synthesized by polyvinylpyrrolidone assisted autocombustion process. X-ray diffraction study confirmed the crystalline nature and phase purity of manganese ferrite. MnFe2O4 nanoparticles calcined at 1000 C for 2.5 hour has spinel crystal structure with lattice constant 8.4163A. The desired stoichiometric ratio 2:1 of Fe:Mn was confirmed by EDAX analysis. An increase in crystallite size was observed in calcined MnFe2O4 nano samples. The dielectric properties of MnFe2O4 were studied at varying frequency range (20kHz - 2MHz) and varying temperature range (100 K - 400 K). The frequency dependence of epsilon' and tan delta was explained by hopping mechanism of electrons between Fe2+ and Fe3+ on octahedral sites of MnFe2O4. Increase in ac conductivity with increasing temperature was observed for all frequencies due to the increase in thermally activated charge carriers and active grain conductivity in the material.