Electrical and magnetic properties of NiCrxFe2-xO4 spinel (0 <= x <= 0.6)

The spinel ferrite NiCrxFe2-xO4 system was synthesized under atmospheric pr essure, and showed single spinel phase in the XRD pattern. The lattice para meter decreased with increasing amount of Cr. For the study of cation distr ibution in this system, magnetic measurements and Mossbauer spectroscopy we re carried out. It was found that ions at the B site moved to the A site, a nd that this system varied from an inverse to a normal spinel structure. It was observed that the magnetic moment of the systems and Curie Temperature decreased by substitution effect. Using a thermopower measurement, this sy stem was found to exhibit n-type semiconductivity. In the electrical conduc tivity measurements, an abrupt change exists near the Tc, owing to the magn etic spin arrangement relaxation. The electrical conduction mechanism of sp inel is an electron transfer between the +2 and +3 cations at the B site, s o called polaron hopping mechanism. From the conductivity result, this syst em is closely related to the electron-hole-compensation between electrons a nd holes. (C) 1999 Elsevier Science S.A. All rights reserved.