Structural and transport properties of nanocrystalline MnFe2O4 synthesized by co-precipitation method

Nanocrystalline MnFe2O4 has been synthesized by co-precipitation methods. X-ray diffraction studies were carried out for the determination of phase purity, crystal structure and average crystallite size. X-ray Absorption Fine Structure spectroscopy has been used to determine the valence state and cationic distribution; these results show that nanocrystalline MnFe2O4 has cubic symmetry with 80% inversion. The electrical transport properties were investigated by employing impedance spectroscopy; it has been observed that the dielectric constant decreases with the increase in frequency, the effects of frequency on dielectrical properties are more prominent in the low frequency region, where dielectric constant increases as temperature is increased. However, the ac conductivity is independent of frequency in the low frequency region, <100 Hz, but increases with frequency above 500 Hz. For ac conduction mechanism two models have been presented: in the lower temperature region (233 K-278 K) the small polaron (SP) model has been suggested, whereas for higher temperature regions (above 278 K) the correlated barrier hopping (CBH) mechanism has been proposed. (C) 2012 Elsevier Masson SAS. All rights reserved.