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In this study, at first the magnetite (Fe₃O₄) nano particles were prepared by sol-gel method under inert atmosphere using ferric nitrate (Fe (NO₃)₃.9H₂O) and ethylene glycol (C₂H₆O₂) as precursors. In the next stage, magnetite nanoparticles were modified by Sodium citrate under Ar atmosphere. Also zinc oxaid (ZnO) nanoparticles were provided via co-precipitation route and heat treatment using ammonium carbonate and zinc acetate as precursors. The precursor was dried and then calcined at 350^oC. Finally with the ZnO and modified Fe₃O₄ nanoparticles, core–shell system was produced. X-ray diffraction pattern (XRD) considered structure characteristic and the size of crystallites. Morphology and the average size of particles were determined by SEM and TEM electron microscope. The UV absorption spectra show that absorption wavelength value for Fe₃O₄/ZnO core-shell is increased in comparison with ZnO pure nanoparticles.  FT-IR Spectra indicated the characteristic absorption of Zn–O bond is at 443/81 cm^-1 and   Fe–O bond is at 540/20 m^-1. Variation of magnetization of samples with respect to the external field was investigated by Vibrating Sample Magnetometer (VSM). Investigation shows that Fe₃O₄ nanoparticles are super paramagnetic but Fe₃O₄/ZnO core-shell nanopowders are ferromagnetic. On the other hand, in core-shell system, the amount of remanence or coercivity field have not had a considerable changes with increasing in molar ratio of ZnO to magnetite.                                                     

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In this research, work nanopowders of Zn_1-xMn_xO (0.0) dilute magnetic semiconductor were prepared via sol-gel autocombustion method. The crystal structure and phase purity of samples were confirmed by X-ray powder diffraction (XRD) analysis. The particle sizes were found to be 5-35 nm from Transmission Electron Microscopy (TEM) and Scherer's formula. The hysteresis in the M-H behavior shows the presence of room temperature ferromagnetism in Mn  doped ZnO. XPS results show that there is Mn²⁺ions in all Mn doped samples. Antiferromagnetic interaction between neighboring Mn-Mn ions suppressed the ferromagnetism at higher doping concentrations of Mn.

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In this article, the Zn_1-xNi_xO nanoparticles with x= 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.08 and 0.1 have been produced by mechanochemical method. To investigate the structural, morphological, optical and magnetic properties of the samples, the X-ray diffraction, field emission scanning electron microscope, UV-visible spectroscopy, photoluminescence and vibrating sample magnetometer have been used. The results of X-ray diffraction revealed that the Zn_1-xNi_xO nanoparticles with x up to x = 0.03 are single-phase and the impurity phase does not appear in the crystal structure of ZnO, but from x = 0.04 the impurity phase appears in this structure. The results of field emissions canning electron microscope showed average particle size of the ZnO increases with Ni doping. The study of UV-visible spectroscopy showed that the optical band gap of the ZnO nanoparticles decreases by Ni doping, which can be due to sp-d exchange interaction between the band electrons and d-electrons of the Ni²⁺ ions. The study of vibrating sample magnetometer of the zinc oxide nanoparticles and Ni-doped samples showed that in the range of magnetic field from zero to about 2000 Oe they are in the ferromagnetic state. In the higher magnetic field (more than 5000 Oe) the
Zn_1-xNi_xO nanoparticles with x = 0, 0.01 are diamagnetic and for x more than 0.01 they show paramagnetic property.

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In this research, ZnO thin films with Al impurity as dopant were coated onto cleaned glass substrates by the spray pyrolysis technique. Crystal structure of the thin films was studied via XRD, and UV-vis spectroscopy was carried out to investigate their optical properties. Finally, in order to study the effect of Al impurity in ZnO thin films, the band structures of both pure and doped systems were calculated and compared using ab initio calculations in the frame work of DFT. The results show that polycrystalline thin films with hexagonal wurtzite structure have been grown, and the crystal size of the (002) ones is 25.41 nm. Moreover, the transmission in the visible region is more than 80%. Furthermore, Fermi energy is shifted into the conduction band in the case of Al doped ZnO which leads to increasing the electrical conductivity and changing the optical transmission threshold.

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In this research, zinc oxide thin films with gallium impurity have been deposited using the spray pyrolysis technique. The structural and optical properties of these films are investigated as a function of gallium doping concentrations. The ZnO and ZnO:Ga  films grown at a substrate temperature of 350 ºC with gallium doping concentrations from 1.0 to 5.0.%. The XRD analysis indicated that ZnO films have nanocrystalline wurzite structure with (002) preferential orientation and grain size varied from 39.1 to 16.1 nm. The optical properties of the thin films have been performed using UV-Vis spectrophotometer and band gap energy values are determined. The results show that the transmittance of these films was higher than 90% in the visible region and by adding Ga up to 5.0%, band gap films have been increased.