Silver-doped ZnO nanoparticles were successfully fabricated at 400• C via a simple and rapid method based on short time solid state milling and calcination of precursor powders. The effect of Ag dilute doping on the structural, optical, and photocatalytic properties of ZnO nanoparticles was investigated by X-ray diffraction (XRD), UV-vis spectrophotometer and photoluminescence (PL) spectroscopy. X-ray analysis revealed that Ag doped ZnO solidified in hexagonal wurtzite structure. The intensity of deep level emission was reduced with increasing silver doping in PL measurement. The X-ray photoelectron spectroscopy (XPS) measurement predicted that Ag was mainly in the metallic state and ZnO was in the wurtzite structure. This metallic state accompanied by unique zinc oxide properties decolorized the methyl violet, efficiently. The first-principles calculation represented Ag deep level in ZnO with an n-type behavior, while in ZnO structure with grain boundary p-type nature via shallow states is dominant same as powder samples as studied in this present work. It was suggested that these Ag-doped ZnO nanoparticles may have good applications in optoelectronics, spintronics and wastewater treatment.
The magnetization of thin films of cobalt ferrite frequently falls far below the bulk value of 455 kAm -1 , which corresponds to an inverse cation distribution in the spinel structure with a significant orbital moment of about 0.6 µB that is associated with the octahedrally-coordinated Co 2+ ions. The orbital moment is responsible for the magnetostriction and magnetocrystalline anisotropy, and its sensitivity to imposed strain. We have systematically investigated the structure and magnetism of films produced by pulsed-laser deposition on different substrates (TiO2, MgO, MgAl2O4, SrTiO3, LSAT, LaAlO3) and as a function of temperature (500-700C) and oxygen pressure (10 -4 -10 Pa). Magnetization at room-temperature ranges from 60 to 440 kAm -1 , and uniaxial substrate-induced anisotropy ranges from +220 kJm -3 for films on deposited on MgO (100) to -2100 kJm -3 for films deposited on MgAl2O4 (100), where the roomtemperature anisotropy field reaches 14 T. No rearrangement of high-spin Fe 3+ and Co 2+ cations on tetrahedral and octahedral sites can reduce the magnetization below the bulk value, but a switch from Fe 3+ and Co 2+ to Fe 2+ and low-spin Co 3+ on octahedral sites will reduce the lowtemperature magnetization to 120 kAm -1 , and a consequent reduction of Curie temperature can bring the room-temperature value to near zero. Possible reasons for the appearance of low-spin cobalt in the thin films are discussed.
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