Combustion triggered route for synthesizing nanostructured nickel substituted cobalt ferrites: investigations on their structural, morphological, electrical, dielectric and magnetic properties

Nanomaterials are found to show interesting properties in the past few decades. One among such promising nanomaterials is nano spinel ferrites which have amazing structural, electrical, dielectric and magnetic properties which fascinates researchers. Our proposed research work deals with the synthesis of the 'as prepared' nickel substituted cobalt ferrites, Ni_xCo_1-xFe₂O₄ where x=0.1(N1), 0.3(N3) and 0.5(N5) by combustion method employing tartaric acid as a fuel. The XRD pattern of the 'as prepared' ferrites showed formation of monophasic cubic spinel structure.There is a decrease in the lattice parameter with an increase in the nickel concentration. The IR spectra depict two characteristic absorption peaks of spinel at around 600 cm^-1 and 400 cm^-1. The SEM micrographs show nearly spherical nano-sized particles, which are largely agglomerated. The EDAX spectra confirmed the presence of desired metal ions on the surface of the ferrites without any impurity peak. The electrical property measurements indicate a decrease in resistivity with increase in temperature, and also decrease with an increase in the cobalt content. The variation of dielectric properties as a function of frequency shows high values at lower frequencies which decreases with increase in frequency and remains constant at high frequencies. The Curie temperature determined from A.C. susceptibility measurements found to increase with increase in nickel content. The VSM plots of all the ferrites indicate ferromagnetic nature and show a decrease in saturation magnetization (Ms) with increase in the nickel content in Ni-Co ferrites. (author)