Publications

Undoped and Mn-doped ZnO nanoparticles (Zn1−x1−xMnxO), with nominal weight percentages (0.00≤x≤0.10)(0.00≤x≤0.10), have been synthesized by co-precipitation technique. The synthesized nanoparticles are characterized by X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Ultraviolet-Visible spectroscopy (UV) and Fourier Transform Infrared Spectroscopy (FTIR). From XRD analysis, the compound ZnMnO3 is formed for x≥0.05x≥0.05 with cubic structure (a=8.3694a=8.3694Å) and its concentration increases with x. Moreover, XRD analysis reveals the wurtzite hexagonal crystal structure for ZnO. The lattice parameters (a and c) of Zn1−x1−xMnxO are calculated and they increase with the doping concentration of Mn as a consequence of the larger ionic size of Mn2+2+ ions compared to Zn2+2+ ions. The crystallite size is calculated for all the samples using Debye–Scherrer’s method (SSM), Williamson–Hall methods (UDM, USDM and UDEDM) and Size-Strain Plot method (SSP), and the results are in good agreement with TEM. The presence of functional groups and the chemical bonding is confirmed by FTIR spectra that shows a peak shift between undoped and doped ZnO. The energy bandgap (Eg)(Eg) is calculated for different concentrations of Mn (0.00≤x≤0.10)(0.00≤x≤0.10) by using the UV-visible optical spectroscopy, between 300nm and 800nm, showing a noticeable drop in EgEg with x. At room temperature, the magnetization of the samples reveals the intrinsic Ferromagnetic (FM) behavior of undoped ZnO, ferromagnetic behavior of ZnxMn1−x1−xO (0.01≤x≤0.03)(0.01≤x≤0.03) and the co-existence of ferromagnetic and paramagnetic behavior for ZnxMn1−x1−xO (0.05≤x≤0.10)(0.05≤x≤0.10). This ferromagnetism is decreased for the doped samples as a consequence of antiferromagnetic coupling between Mn ions. The two samples correspond to x=0.01x=0.01 and x=0.10x=0.10, tend to be superparamagnetic because of the formation of single domain particles as a consequence of small particle size. x=0.03x=0.03 shows an optimum value of Mn concentration for maximum saturation magnetization and the best ferromagnetic nature.