Less magnetic and larger Zr4+–Zn2+ ions co-substituted structural and magnetic properties of ordered Li0.5Fe2.5O4 nanoparticles

Samples of Zr4+ and Zn2+ co-substituted Li0.5Fe2.5O4 nanoparticles were prepared by the sol–gel auto-combustion method. The samples were obtained by annealing at relatively low temperature at 600 °C and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM) and Fourier transform infrared (FT-IR) spectroscopy. Lattice parameter, X-ray density, specific surface area and porosity were found to increase, whereas bulk density and crystallite size showed the decreasing trend with the Zr4+ and Zn2+ substitution. Cation distribution estimated from XRD results suggests that Zn2+ and Li+ occupy tetrahedral A- and octahedral B-site respectively, whereas Zr4+ and Fe3+ occupy both the available sites. The FT-IR spectra show two major absorption bands at 715–749 cm−1 (ν1) and 484–507 cm−1 (ν2) related to spinel structure of ferrite. Magnetization results exhibit collinear ferrimagnetic structure for x ≤ 0.2, and changed to the non-collinear for x > 0.2. Observed and calculated magneton number shows discrepancy in their values that gives rise to Yafet–Kittle angle for x > 0.2.