Hyperfine and electrical properties of nickel -chromium ferrites

Spinel ferrite series of NiCrxFe2-xO4 with x ranges from 0.0 to 1.0 has been prepared. Moessbauer effect spectra recorded at room temperature for these compounds show a ferrimagnetic ordering and fitted into two Zeeman sextets due to ferric ions at tetrahedral A - and octahedral B -sites. The obtained parameters are discussed as a function of Cr concentration. Using the cation distribution obtained from the Fe3+ ratio at the two sublattices, the magnetic moments of these compounds are found to exhibit a collinear ferrimagnetic structure. Results of conductivity measurements for these materials as a function of frequency and temperature reveal a semiconducting behavior. All compositions exhibit a transition temperature, which decreases as Cr concentration increases. The dielectric permittivity and dielectric losses are discussed in the light of hopping conduction mechanism occurred at the octahedral B - site