Effect of cobalt substitution on structural, elastic, magnetic and optical properties of zinc ferrite nanoparticles

The aim of this study is to investigate in-depth the effect of Co2+ ions doping on ZnFe2O4 nanoparticles in term of morphology, magnetic and optical properties. Zn1-xCoxFe2O4 (x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5) powders were prepared by co-precipitation method. X-ray diffraction (XRD) and Energy Dispersive Spectroscopy (EDS) confirmed the incorporation of Co2+ ions within ZnFe2O4 host lattice, and an increase of the crystallite size from 37 to 51 nm in agreement with TEM analysis. FTIR revealed a slight change in two main bands u(1) and u(2) in the frequency range of 400-4000 cm(-1), which caused by stretching vibrations at the A-and B-sites respectively. The elastic moduli such as stiffness constant, Young's modulus, rigidity modulus, bulk modulus, Poisson's ratio, wave velocity and Debye temperature have been calculated using FTIR data. VSM showed transformation of magnetic behavior from paramagnetic to ferromagnetic as a result of Co2+ ions doping. With higher Co2+ (x = 0.2 to x = 0.5) content, the saturation magnetization (Ms) increased rapidly from 5.7 emu/g to 82 emu/g respectively. The remanance magnetization (Mr) and coercivity (Hc) were influenced by Co2+ content too and this was mainly related to the change in crystallite size. The optical band gap (Eg) of Co-Zn ferrite samples was determined by means of diffuse reflectance spectra. The optical band gap value estimated from Tauc plots was found to decrease from 1.89 to 1.31 eV with increasing Co2+ content. (C) 2017 Elsevier B.V. All rights reserved.