Structural and DC conductivity studies of samarium substituted Ni–Zn ferrites

G J Shankaramurthy; H S Jayanna

Volume : VI, Issue : IV, April - 2016

Structural and DC conductivity studies of samarium substituted Ni–Zn ferrites

G J Shankaramurthy, H S Jayanna

Abstract :

Polycrystalline ferrites having the general formula NixZn1–xFe2–ySmyO4 (x = 0.00, 0.25, 0.50, 0.75, 1.00; y = 0.00, 0.05, 0.10) were prepared by standard ceramic method. The samples were characterized by XRD techniques. The single–phase spinel formation of ferrites was confirmed by X– ray diffraction technique. The IR spectra show four absorption bands in the frequency range 300 cm–1 to 800 cm–1. The first band ν1 around 600 cm–1 and second band ν2 around 400 cm–1 were assigned to the octahedral metal complexes. The other low frequency bands ν3 assigned to the octahedral metal–oxygen complexes, and ν4 related to some type of viations of the tetrahedral of octahedral metal oxygen complexes.The DC electrical conductivity of the palletized samples was measured by two–probe method in the temperature range 300K to 840K. The electrical conductivity in ferrites can be explained on the basis of exchange of electrons between ions of the same element that are present in more than one valence state, distributed randomly over equidistant crystallographic lattice sites. The electrical conductivity in ferrites to be due to the simultaneous presence of both Fe2+ and Fe3+ ions and due to electron hopping between Fe2+ and Fe3+ ions of octahedral sites. The electrical properties of ferrites are affected by the distribution of cations in sites by magnetic and non magnetic substitutions, the amount of Fe2+ ions present, sintering conditions, grain size and grain growth. The experimental results reveal that the DC conductivity increases as temperature increases and as the Zn2+ and Sm3+ ion content decreases. The electrical conduction mechanism in these ferrites is on octahedral sites. The activation energy for ferrimagnetic region is lower than in paramagnetic region. The addition of Sm3+ impedes conduction in samples. Thus, the activation energy is higher for Sm3+ substituted samples than those for the corresponding undoped samples in both the regions.