Electrical and magnetic properties of spinel ZnCr2-xFexO4 (0≤x≤1.0)

The spinel ZnCr2-xFexO4 (0 less than or equal to X less than or equal to 1.0) systems were synthesized in air under atmospheric pressure, and showed single spinel phases in the XRD patterns, and lattice parameters increased by increasing Fe3+ ion substitution. From IR measurement, it was found that the Zn2+ ion was only at tetrahedral site and the Fe3+ ion was only at octahedral site by substitution. In the electrical conductivity measurements, it was shown that the more substitution of Fe ions, the less conductivity because of electron-hole compensation of Fe2+-hole produced from Fe3+ ion. Electroconduction mechanism was a small polaron hopping mechanism, which was explained by electron exchange between Cr3+ and Cr4+, and between Fe3+ and Fe2+. The thermal EMF measurement showed that these systems were n-type semiconductors. From the magnetic and susceptibility measurements, the spinel ZnCr2-xFexO4 systems were found to exhibit anti-ferromagnetism. It was also found that the A site was occupied by only Zn2+ ion, and that magnetic moments depend upon B-B sub-lattice interaction. (C) 2002 Published by Elsevier Science B.V.