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

Abstract The aim of this study is to investigate in-depth the effect of Co 2+ ions doping on ZnFe 2 O 4 nanoparticles in term of morphology, magnetic and optical properties. Zn 1-x Co x Fe 2 O 4 (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 Co 2+ ions within ZnFe 2 O 4 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 υ 1 and υ 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 Co 2+ ions doping. With higher Co 2+ (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 Co 2+ 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 Co 2+ content.