La3+ doped LiCo0.25Zn0.25Fe2O4 spinel ferrite nanocrystals: Insights on structural, optical and magnetic properties

Abstract

Abstract This paper addresses the manipulation of structural, morphology, optical and magnetic properties of LiCo0.25Zn0.25Fe2O4 ferrite via incorporation of different proportions of La3+ at the expense of iron ions using a sol-gel method. The samples were characterized using the X-ray diffraction technique (XRD), Fourier transform infrared (FT-IR) spectroscopy, the energy dispersive X-ray spectra (EDX), inductively coupled plasma optical emission spectroscopy (ICP-OES), high resolution scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area analysis, ultraviolet-diffuse reflectance spectroscopy (UV-DRS), and vibrating sample magnetometer (VSM) technique. The Rietveld refinements of the samples indicate that at higher concentrations of La3+, nanostructures with dual phase, i.e. cubic spinel and orthorhombic LaFeO3 perovskite with space group (Pbnm) appear. Optical studies show that the energy band gap (Eg) of the bare LiCo0.25Zn0.25Fe2O4 ferrite sample (2.18\xa0eV) reaches up to 2.47\xa0eV\xa0at x\xa0=\xa00.06 and above this concentration, it drops sharply to 2.00\xa0eV. Although the saturation magnetization and the coercivity of LiCo0.25Zn0.25LaxFe2–xO4 are lower than that of LiCo0.25Zn0.25Fe2O4 NPs. Overall, the superparamagnetic nature and low values of saturation magnetization and coercivity of LiCo0.25Zn0.25LaxFe2-xO4 NPs are suitable to be applied in transformers core.