NiO nanoparticles with sizes of 3.5–12.4 nm were
grown by
thermal decomposing of nickel acetate at different temperatures in
NaCl and Li2CO3 alkalisalts. The properties
of the nanoparticles were characterized by X-ray diffraction spectrometer,
transmission electron microscope, absorption spectrometer, micro-Raman
microscope, and superconducting quantum interference device. The effects
of the nanoparticle sizes on the crystal structure, exciton ground
state energy, vibration modes, and magnetic properties were studied.
Lattice parameter of NiO increases with a decrease in nanoparticle
sizes. The band gap of NiO nanoparticles increases with a decrease
in the nanoparticle size. LO modes of NiO nanoparticles shift red,
and the intensity increases with a decrease in the nanoparticle sizes.
Surface phonon modes are observed. Bifurcation temperature and blocking
temperature of NiO nanoparticles shift to lower temperature with a
decrease in nanoparticle sizes. Two peaks are present in all nanoparticles’
zero-field-cooled magnetization curves, and the saturation magnetization,
remanet magnetization, and coercivity increase with a decrease in
the nanoparticle sizes. The nanoparticles exhibit size-dependent anomalous
magnetic properties that make the remagnetization curve surpass the
initial magnetization curve in the M–H hysteresis curves taken at 5 K.
Undoped and Al-doped ZnO films were synthesized by atomic layer deposition at 150°C and then annealed at 350°C in different atmospheres. Effects of doping and annealing on the film growth mode and properties were investigated. The undoped film has strong UV emission and weak Zn interstitial emission. Annealing introduces O vacancies, decreases Zn interstitials, and results in weakening and blue-shifting of the UV emission which is sensitive to annealing atmosphere. Al doping induces the film growing with its c-axis parallel to the substrate surface. It also introduces non-radiative centers and weakens the UV emission. Al doping widens the film bandgap, which has a quadratic dependence on Al content. Al doping decreases the film resistivity to 5.3 × 10−3 Ω · cm. Annealing has little effect on photoluminescence of the doped films, but it degrades undoped and doped ZnO film conductivity dramatically; and the degradation depends on the annealing ambient.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.