Rietveld refinement and switching properties of Cr3+ substituted NiFe2O4 ferrites

A series of ferrite samples of the chemical formula NiCrxFe2-xO4 (x = 0.0 to x = 1.0) were prepared by a wet chemical co-precipitation method and annealed at 600 degrees C for 4 h. The prepared samples were shown to have the cubic spinel structure by applying the full pattern fitting of the Rietveld method using the Full Prof program. The unit cell dimension, discrepancy factor and interatomic distance have been determined. It was observed that the unit cell dimensions decrease with an increase in Cr3+ content x. The grain size of the synthesized powder has been determined from XRD data and strain graph. The grain size of all samples is in the range of 26 to 40 nm. The IR spectra show three absorption bands in the wave number range of 200 to 800 cm(-1). All samples were studied for electrical switching. Current controlled negative resistance type switching was observed for all samples. (C) 2009 Elsevier B.V. All rights reserved.