الفهرس 
ACKNOWLEDGEMENTS
Magnetic semiconductorsOnly 14 pages are availabe for public view
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Abstract
Ni-doped ZnO nanoparticles (NPs) synthesized by Coprecipitation method. This method is simple and low cost effective. The structure, optical and magnetic properties of prepared samples were investigated using X-ray diffraction (XRD), Energy dispersive spectroscopic analysis (EDS), Scanning electron microscope (SEM), Transmission electron microscope (TEM), UV–visible absorption spectroscopy (UVVis), Photoluminescence (PL), Fourier transform infrared (FTIR), Raman Spectroscopy, Vibrating sample magnetometer (VSM) and Electron spin resonance (ESR). A typical XRD pattern revealed hexagonal wurtzite structure. EDS spectroscopy was used to identify the elemental constituents of a material. In order to investigate the shape and size distribution for Zn1-xNixO, SEM and TEM images were obtained. Also, TEM investigations give further insight to the morphology and the structural features of Ni-doped ZnO nanorods. The energy band gap and optical properties were also characterized. Photoluminescence spectra of Ni doped ZnO were measured using UV (325nm) as exciting wavelength. All samples display ultraviolet (UV) near band-edge (NBE) emission due to free excitonic emission through an exciton - exciton collision. The presence of absorption bands and their position not only depend on crystal structure but also depend on chemical composition and the particle morphology. The magnetization behavior was discussed considering the magnetic shape anisotropy of the small size ZnO nanorods (NRs). The observed value of Mr/Ms equals 0.5 which is a typical value for randomly oriented NRs having uniaxial magnetic anisotropy. In addition to the uniaxial anisotropy, the surface effects play a crucial role resulting from the in-plane magnetic anisotropy at the NR surface which aligns the magnetic moments in the surface plane. The surface magnetic moments require higher energy to rotate out of the surface resulting in larger magnetic coercivity. On the other hand, the surface band bending results in a charge separation of carriers which enhances the mediated ferromagnetic exchange coupling at the NRs surface. These effects haven’t been well highlighted in the previous reported literature that discussed the magnetic properties of diluted magnetic semiconductors. The shape anisotropy in Diluted Magnetic semiconductor (DMS) samples is an important parameter, however magnetocrystalline anisotropy is not expected to exist in DMS.