Electrical switching in CdxCo1−xFe2−yCryO4 system

Polycrystalline samples of CdxCo1−xFe2−yCryO4 (x = 0, 0.25, 0.50, 0.75, and 1.00; y = 0, 0.15, and 0.30) were prepared by standard ceramic method and characterized by X-ray diffraction (XRD), IR, and scanning electron microscopy (SEM). The pelletized samples were studied for electrical switching. The current controlled negative resistance (CCNR)-type switching is observed in samples with x = 0.75 and 1.00 (y = 0, 0.15, and 0.30), i.e., paramagnetic materials only. It was found that the switching field required for Cd ferrites is lowest. The Cr3+ substitution in this ferrite increases the required switching field, while the same in Cd-rich (x = 0.75) Cd–Co ferrite initially decreases it considerably for y = 0.15 and then increases it for y = 0.30. It was also found that the observed phenomenon is reproducible, having no aging effect. The results are interpreted on the basis of cation distribution, exchange between divalent and trivalent ions on B sites under applied electric field and other models.