Thesis (M.Sc.) - Cairo University - Faculty of Science - Department of Analytical Chemistry

A comparative study of structural and magnetic properties for the Zn²⁺ and La³⁺ ions co-doped magnetite nanoparticles of the general formula [(1-x)Fe₃O₄:Zn:xLa where x =0.0, 0.1, 0.15, 0.2, 0.25 and 0.3] were prepared via co-precipitation method under oxygen and nitrogen atmospheres. The stoichiometric ratios of the elements in the given general formula had been proved and confirmed by elemental analyses of the prepared nano-materials by spectrophotometric, ICP and atomic absorption data. Various analytical and characterization techniques have been used to analyze and characterize the prepared nanoparticles. X-ray diffraction (XRD) confirms the formation of one single phase of nanoparticles components with average crystalline size ranges from 6-9 nm at oxygen atmosphere and 4.6-8 at the nitrogen atmosphere.These size values had been calculated by the Debye-Scherrer formula.The morphology of Zn²⁺ and La³⁺ ions co-doped magnetite nanoparticles was studied using field emission scanning electron microscopy (FE-SEM) and High-resolution transmission electron microscopy (HRTEM).Optical properties were demonstrated by UV{u2013}visible{u2013}NIR spectrophotometer.The high absorbance values of Zn La(x)Fe(3-x)O₄ were found to 80-97 and 80-99 % in the visible wavelength range of 400-800 nm for the prepared samples in presence of O₂ and N2 gas at room temperature, respectively; proved the lower values of energy bandgap in both conditions. The lowering of energy bandgap of 1.89 eV for nanoparticles prepared in O₂ gas and 1.78 eV for prepared in N₂ gas in most samples may be attributed to the incorporation of Zn cation. Magnetic properties of the given samples, obtained from vibrating sample magnetometer (VSM); show that most of these samples exhibit almost superparamagnetic behavior

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