الفهرس 
ACKNOWLEDGEMENTSOnly 14 pages are availabe for public view
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Abstract
The main goal of this master is the preparation and characterization of nanomaterial’s based on undoped and Cr doped ZnO nanoparticles with composition of Zn1-xCrxO ((x = 0, 0.02, 0.04, 0.06 and 0.08) that were prepared by co-precipitation method. The calcinations temperature was identified in terms of differential scanning colorimetry thermo gravimetric analysis (TGA) and its differentiation in order to obtain nano crystalline powder. The elemental compositions of the ZnO and Cr-doped ZnO nanostructures were determined by EDAX analyses. Structural properties of Zn1-xCrxO (x = 0.0, 0.02, 0.04, 0.06 and 0.08) were investigated by XRD that illustrate the XRD patterns with distinct peaks, corresponded to the (100), (002), (101), (102), (110), (103), (112) and (201) lattice planes, reveals that as prepared nanoparticles have a wurtizte (hexagonal) structure from XRD analysis using Williamson-Hall method, the crystallite size decreases and the lattice strain increases but the lattice strain increases with increasing Cr at expense of Zn content in the Zn1−xCrxO nanoparticles. Such the increase in the lattice strain and the decrease in the crystallite size reflect the increase in concentration of lattice imperfections due to addition of Cr to the ZnO. TEM studies have also been checked for Zn1-xCrxO (x = 0.0, 0.04and 0.08) nanoparticles. The mean particle size in terms of TEM is found to be higher than that obtained from XRD calculation because the TEM gives the particle size that may consist more than one crystallite. FTIR spectra of undoped and Cr-doped ZnO nanoparticles carried out in the wave number range 2000 to 400 cm-1. According to these spectra, the absorption significant band at 448 and 530 cm-1 is assigned to the characteristic stretching of Zn-O and Cr-O bond. Peak located at 880 cm-1 are due to C-H (out-of-plane bending). Absorption band at 3435 cm-1 arises due to the stretching mode of O-H group that reveals the existence of a small amount of water absorbed by the ZnO nanostructure. Stretching modes of C-O and C=O are observed at 1460 and 1626 cm-1. The peak located at 2926 cm-1 is due to asymmetric C-H bonds. It is noticeable from the given FTIR spectra that after doping wave number increases, showing blue shift which is credited to optical phonon confinement of nanostructures. The spectrophotometer (in wavelength range 350-1100 nm) was adopted to obtain the absorbance for undoped and Cr doped ZnO. The energy band gap was calculated from the Tauc relationship. It was reported that the band gap decrease with increasing Cr concentration. It may be attributed to the s-d and p interactions and the quantum confinement.The magnetic measurements show that the Cr-doped ZnO samples are ferromagnetic in nature with a well- defined hysteresis at room temperature. and the remnant magnetization increase with increasing doping concentrations. The appearance of ferromagnetism in Cr-doped ZnO nanoparticles may attributed to two factors, the first is due to the increasing of the number of defects and oxygen vacancies, the second is due to the exchange interactions between Cr ions and O ions spin moments, for instance.