Papers by Keyword: Colloid

Abstract: The Ag nanoparticles colloid was prepared by pulsed laser ablation for different time in 10 ml distilled water without any surface active agent, and it was analysed by means of UV-visible spectrophotometer and transmission electron microscopy (TEM). The results showed that the ablation efficiency and absorbance increased fast and shift to higher energies with increasing ablation time from 5 to 10 min, then increased slowly from 10 to 20 min, and increased fast again from 20 to 25 min. The morphologies of most Ag nanoparticles were nearly spherical. The average diameter and its distribution decreased from 5 to 7.5 min, then increased from 7.5 to 15 min, and decreased from 15 to 25 min.

Abstract: 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.

Abstract: To prepare the vibrated casting slurries of waste tile particles, ultrafine colloids of the waste tile was added as a binder materials and as a thixotropic agent to avoid segregation between large and fine grains. The plasticity of the slurries was controlled by the rheology of colloids of the waste tile. To give thixotropic behavior, the dispersion and coagulation behavior of the colloidal suspension were investigated by the zeta potentiometer. The point of zero charge of the suspension was shown near pH 5 and maximum zeta potential was -55[mV] near pH 11. Maximum agglomerate particles were appeared near to the point of zero charge. The bending strength and water absorption of sintered bodies were more than 8.35kgf/cm2, and less than 5.0% above 1100 oC respectively. In addition, crystalline phase of sintered bodies were quarts and mullite. The micro-structure of the sintered body has a uniform pore size and distribution.

Abstract: Zinc Oxide (ZnO) is a very useful as a solid state gas sensor material. In chemical sensing the surface and interface interactions between the analyte molecules and the sensing material is all but important that is read through the changes in electrical conductance. In that sense, nano-objects with a large surface atom/bulk atom ratio, like nanoparticles and nanowires, are potentially the best chemical sensors. The mechanism envisioned involves the adsorption (and eventually diffusion) of the analyte molecule at the surface that induces a change in the electrical resistance of the nano-object. The most convenient way to measure changes in electrical resistance in such devices is to obtain the specific material as nanowires or as connected nanoparticles. Here, we will discuss about a low-temperature wet-chemical process of synthesizing ZnO nanoparticles, nanowires and nanobelts for application as gas sensors.