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Nickel-doped zinc-oxide nanoparticles are synthesized by the solvothermal method at different doping concentrations (x = 0.02, 0.04, 0.06, and 0.08). The structural properties of undoped and nickel-doped zinc oxide nanoparticles are carried out. X-ray diffraction analysis confirms the hexagonal wurtzite structure (belonging to the space group p63mc) and optical properties are analyzed through UV–visible, Fourier-transformed infrared, and hotoluminescence. Energy bandgap values are found using the Tauc plot method. The Lande splitting factor is calculated using EPR analysis. Magnetic properties of the sample are measured using a vibrating sample magnetometer at room temperature. It is observed that their behavior changes from paramagnetic to superparamagnetic structure with an increase in their doping values. In the large saturation magnetization, it is very suitable for magnetic storage device applications. [ABSTRACT FROM AUTHOR]

Zn1-xNixO aerogel nanopowders with nickel concentration in the range of 0.05 ⩽ x ⩽ 0.25, were synthesized by the sol-gel processing technique and post-annealed in air at 500 °C. Structural, vibrational, thermal and magnetic properties of the as-prepared and annealed Zn1-xNixO powdered samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman scattering, thermal gravimetric analysis (TGA) and electron paramagnetic resonance (EPR) spectroscopy. In addition to the ZnNiO phase, XRD analysis revealed the formation of a secondary NiO phase when the Ni content was greater than or equal to 10 %. The TEM images confirm that the particle size is in the range of 20 nm to 40 nm, in accordance with XRD results, and the particles are well dispersed. Raman scattering measurements confirm the wurtzite structure of the synthesized Zn1-xNixO nanopowders and show that intrinsic host-lattice defects are activated when Ni2+ ions are substituted to the Zn sites. Room temperature ferromagnetic order was observed in all of the samples and was strongly dependent on the Ni content and thermal annealing. These results indicate that the observed room temperature ferromagnetism in ZnNiO may be attributed to the substitutional incorporation of Ni at Zn sites. [ABSTRACT FROM AUTHOR]

In this research, Ni-doped ZnO (ZnNiO: x = 0.02, 0.04, 0.06, and 0.08) nanoparticles have been synthesized using a simple wet chemical precipitation method. X-ray diffraction analysis reveals the Ni-doped ZnO crystallized in a hexagonal wurtzite structure and confirming phase purity. The lattice parameters of Ni-doped ZnO decreased slightly with increasing doping concentration. The vibrating sample magnetometry measurement results of samples at room temperatures and annealed at 400 °C show a weak magnetic hysteresis loop that confirms the ferromagnetic properties of the samples. The origin of magnetic behavior in Ni-doped ZnO could be the presence of O vacancies and exchange interaction between Ni ions. Also, the magnetic saturation of the samples increased with increasing Ni concentration in the range of 1.2 × 10 to 5.0 × 10 (emu/g). The effects of annealing on the morphology of Ni-doped ZnO nanoparticles were investigated using scanning electron microscopy. The crystallite size of the nanoparticles increased and the magnetic saturation decreased slightly at the annealing temperature 400 °C. [ABSTRACT FROM AUTHOR]

Zn 0.98 Ni 0.02 O nanoparticles have been synthesized successfully by the sol–gel method. Effects of thermal annealing temperature (400, 500 and 600 °C) and atmosphere (argon and air) on the structural, magnetic and optical properties of the samples were investigated. Results indicated that Ni ions were successfully incorporated into the ZnO matrix and replaced Zn ions. By varying temperature and atmosphere of the thermal annealing treatment, we found that Zn 0.98 Ni 0.02 O nanoparticles exhibited ferromagnetism at room temperature and this behavior was believed to be from oxygen vacancies. [ABSTRACT FROM AUTHOR]