Evaluation of New Properties of Calcined Magnetite Doped with Zinc and Lanthanum Nanoparticles Prepared in Oxygen and Nitrogen Atmospheres

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Abstract The aim of the present research is the preparation of magnetite nanoparticles doped with Zn and La of the general formula ZnLa(x)Fe(3-x)O4 where x =0.0, 0.1, 0.15, 0.2, 0.25 and 0.3; which were prepared via co-precipitation method, separated and calcined at 800oC under oxygen and nitrogen atmospheres. The stoichiometric ratios of the elements in the given general formula had been proved and confirmed by elemental analyses using XRF. Various techniqueshave been used to analyze the prepared nanoparticles. X-ray diffraction (XRD) confirmed the formation of one single phase of nanoparticles components with average crystalline size ranged from 6 to 9 nm at oxygen atmosphere and from 6 to 8 at nitrogen atmosphere.These size values had been calculated by Debye-Scherrer equation. The optical properties carried out by Cary Eclipse fluorescence spectrophotometer.The morphology of the prepared magnetite nanoparticles was studied using field emission scanning electron microscope (FE-SEM) and high-resolution transmission electron microscope (HRTEM). Optical properties were demonstrated by UV–visible–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. These proved the lower values of energy band gap in both conditions. The lowering of energy band gap 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 incorporation of Zn cation. These results are confirmed by photo luminscence spectra (PL) measurements of the prepared samples. Magnetic properties of the given samples obtained from vibrating sample magnetometer (VSM);showed that most of these samples exhibited almost superparamagnetic behavior. These magnetic values (32.87 and 24.79 emu/g) infer super saturation magnetization of the given samples prepared in O2 and N2 gas at room temperature, respectively. Examination of the magnetic properties revealed decrease in saturation magnetization with increasing La ion concentrations incorporation up to x = 0.3. The evaluated magnetic and optical properties of the novel prepared ZnLa(x)Fe(3-x)O4nano-materials revealed their possible use in different industrial fields like bio-applications, in electronic components, cosmetics, antibacterial agents, and in solar cells. The antibacterial activity study of the prepared NPs revealed them highly efficient against different kinds of bacteria that increase with increase of La % doped in their entity.

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