Formation Of Zinc Oxide Nanoparticles Research Articles

Bacillus cereus as a biotemplating agent for the synthesis of zinc oxide with raspberry- and plate-like structures

Currently the development of green chemistry approach with the use of biomaterial-based activities of microbial cells in the synthesis of various nanostructures has attracted a great attention. In this study, we report on the use of bacterium, Bacillus cereus as a biotemplating agent for the formation of zinc oxide nanoparticles with raspberry- and plate-like structures through a simple thermal decomposition of zinc acetate by maintaining the original pH of the reaction mixtures. Possible mechanism on the formation of the nanostructures is proposed based on the surface chemistry and biochemistry processes involved organic-inorganic interactions between zinc oxide and the microbial cells.

Fabrication and characterization of zinc oxide nanoparticles by DC arc plasma

Zinc oxide nanoparticles were synthesized by DC arc plasma in pure oxygen atmosphere. High DC currents were passed through two approaching zinc rods in different oxygen pressures between 50 to 5000 mbars. Samples were characterized by TEM, SEM, XRD and electron diffraction analysis. The formation of zinc oxide nanoparticles were successfully proved by those analyses, although in some cases we had some unwanted materials. The XRD patterns show crystalline formation of zinc oxide, but in low pressures we have an excess peak belong to pure zinc. The height of this peak was reduced by increase in oxygen pressure and finally vanished completely at high pressure. The TEM and SEM images of samples show that in low pressures the samples mainly tend to have rod like shapes structures, but by increasing the oxygen pressure the structures steady revolve to the hexagonal nanocrystals. Upon the resulted data, the best conditions of arc plasma for desire product were inferred.

The effect of parameters on the formation of ZnO nanoparticles by statistical experimental design method in vibrating milling process

Zinc oxide (ZnO) nanoparticles were synthesized by vibrating milling process. Amorphous ZnO powders prepared by the milling process were washed with water to remove NaCl, and then the powders were sintered at 300–500 °C for 2 h. In this work, statistical experimental design method was used and it was found that the particle size and size distribution of ZnO nanoparticles were dependent on the milling time and mass ratio of ball to powder. Therefore, ZnO nanoparticles with about 100 nm of mean crystallite size were obtained.

Production of Zinc Oxide Nanoparticles by Liquid Phase Processing: an Investigation on Optical Properties

In the recent years, many researchers have been interested in nanoparticles because of their unique properties. In this study, a method for producing ZnO nanoparticle colloids is proposed. The colloids were characterized by spectroscopic analyzer. By absorption spectrum study, we found out that colloids were consisted of nanoparticles with less than 10 nanometer size. The quantum confinement effect in these spectrums was recognized through blue shift of onset absorption wavelengths. These wavelengths shift from 370 nm to 340 nm by decreasing the particles size. Transmittion electron micrographs showed formation of zinc oxide nanoparticles.

Formation of zinc-oxide nanoparticles in SiO2 by ion implantation combined with thermal oxidation

Metal-ion implantation followed by thermal oxidation was carried out to fabricate zinc-oxide (ZnO) nanoparticles (NPs) in silica glass (SiO2). A SiO2 substrate was implanted with Zn+ ions of 60keV up to 1.0×1017ions/cm2. In the as-implanted state, the sample shows a strong absorption peak at ∼4.8eV and a weak one at ∼1.2eV due to Zn metallic NPs. After annealing in oxygen gas at 700°C for 1h, the absorption in the visible region disappears and a new absorption edge appears at ∼3.25eV. The grazing incidence X-ray diffraction (GXRD) confirms the formation of ZnO NPs. The ZnO NPs show a photoluminescence (PL) peak at 3.32eV under pulsed nitrogen-laser excitation at 3.68eV. Annealing at 900°C induces an additional shift of the absorption edge to ∼5.3eV. The additional shift indicates the formation of a Zn2SiO4 phase which was confirmed by GXRD.

Formation of zinc oxide nanoparticles by mechanochemical reaction

The synthesis of zinc oxide (ZnO) nanocrystallites by mechanochemical reaction of ZnCl2 and Na2CO3 with NaCl as diluent and following thermal treatment was investigated using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Calcination of the as milled powder at 600°C in air and removal of NaCl through washing formed ZnO nanocrystallites with an average crystal size of ~ 21 nm, which increased with increasing thermal treatment temperature. Milling time and NaCl/ZnCl2 molar ratio exerted prominent effects on the crystal size of the ZnO nanoparticles. The mechanism of nanocrystallite growth is discussed.

Green Photoluminescence Suppression in ZnO Embedded in Porous Opal

The photoluminescence (PL) and transmittance characteristics of zinc oxide (ZnO) embedded in voids of silicon dioxide synthetic opal by the technologically simple sol–gel method are reported. The uniform formation of ZnO nanoparticles inside of the opal matrix can be obtained after its infiltration in an aqueous solution containing a zinc nitrite hexahydride precursor followed by thermal annealing. The green-PL suppression is observed due to the inhibition of spontaneous emission through oxygen vacancies in ZnO. The strong redshift of the transmittance characteristics signifies the essential filling of voids in the fcc packed structure. The infiltration of nanocrystals into synthetic opal may be used as an inexpensive method for the fabrication of polycrystalline ZnO with dominant ultraviolet-blue PL. This technology may also be promising for the fabrication of color light sources, such as RGB pixels in secondary-electron-emission or field-emission displays.

Formation of zinc oxide nanoparticles in supercritical water

Supercritical water provides an excellent reaction medium for hydrothermal synthesis of metal oxide nanoparticles. In this work, zinc oxide nanoparticles are produced by oxidation of zinc acetate in supercritical water in a continuous tubular reactor. Less than 1 min is enough for the reaction to occur, and the temperatures are much lower than in the flame combustion or zinc evaporation processes. Effect of flow rates and feed concentrations are studied. Based on transmission electron microscopy and dynamic light scattering analyses, spherical zinc oxide particles are obtained in the range 39–320 nm.