Structural and Magnetic Studies of Nano-crystalline Ferrites MFe2O4 (M = Zn, Ni, Cu, and Co) Synthesized Via Citrate Gel Autocombustion Method

Abstract

Nano-crystalline ferrites with the chemical formula MFe2O4 (M = Zn, Ni, Cu, and Co) were synthesized via autocombustion route with citric acid as fuel. The ratio of citric acid to metal nitrate was taken as 1:1. The synthesized samples were characterized by powder X-ray diffraction and far-IR spectroscopy. The measured lattice constants and observed characteristic IR absorption bands of all samples were in good agreement with the reported values and showed the formation of a cubic spinel structure. The crystallite sizes of all samples were determined using high-intensity peaks and a W-H plot. The crystallite sizes of all samples were observed to be in the range of 16–26 nm with the least crystallite size of 16.8 nm for copper ferrite. All structural parameters were calculated using an experimental lattice constant and an oxygen positional parameter and correlated with far-IR results. Zinc and copper owing to their large cation radii showed the expansion of the lattice in view of the oxygen positional parameter. Magnetic measurements were carried out using a vibrating sample magnetometer at room temperature, and parameters such as saturation magnetization, coercivity, remanence, squareness ratio, and Bohr magnetons were calculated. Among all synthesized nano-ferrites, cobalt nano-ferrite showed the highest saturation magnetization of 41 emu/g, whereas zinc ferrite displayed a low saturation magnetization value of 12.87 emu/g.