Structural, Morphological, Optical, and Room Temperature Magnetic Characterization on Pure and Sm-Doped ZnO Nanoparticles

摘要

Nano crystalline Zn_(1-x)Sm_xO, (0.00 ≤ x ≤ 0.10), were prepared by wet chemical coprecipitation method. The effect of samarium doping on the structural, morphological, optical, and magnetic properties of ZnO nanoparticles was examined by X-ray powder diffraction (XRD), Transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), Ultravioletvisible spectroscopy (UV) and M-H magnetic hysteresis. XRD analysis showed the hexagonal wurtzite structure of ZnO. The absence of Sm_2O_3 as separate phase may be attributed to the complete dissolving of samarium in ZnO lattice. The lattice parameters (a and c) of Zn_(1-x)Sm_xO were calculated and they fluctuated with the increase of Sm doping which indicated that the structure of ZnO was perturbed by the doping of Sm. The crystallite size was computed for all the samples using Debye- Scherrer’s method. The crystallite size decreased with the increase of Sm doping. TEM micrographs revealed that the size and the shape of the ZnO nanocomposites were changed by modifying the doping level of samarium. FTIR analysis spectrum confirmed the formation of ZnO phase and revealed a peak shift between pure and Sm-doped ZnO. The band gap energy and Urbach energy were calculated for Zn_(1-x)Sm_xO, (0.00 ≤ x ≤ 0.10). The band energy gaps of pure and Sm doped ZnO samples are in the range 2.6–2.98 eV. M-H hysteresis inspection, at room temperature, showed that the pure ZnO exhibited a ferromagnetic behavior incorporated with diamagnetic and paramagnetic contributions. Ferromagnetic behavior was reduced for the doped samples with x = 0 01 and x = 0 04. The samples with x = 0 02 and 0.06 ≤ x ≤ 0.10 tend to be superparamagnetic. The saturation magnetization (M_s), the coercivity (H_c), and the retentivity (M_r) were recorded for Zn_(1-x)Sm_xO, (0.00 ≤ x ≤ 0.10).