Abstract: Barium zirconate, a perovskite oxide has been synthesized by a new procedure
using solid state metathesis reaction precursors subjected to sonication. We report
the lowest temperature of synthesis with particle size ranging from 20 to 30 nm.
The initial stage involves formation of composite hydroxide nanoparticles by the
solid state reaction of precursor salts with KOH at ambient temperature followed
by sonication. BaZrO3 formation as a consequence of ultrasonicator output power
variation and ultrasonic time variation has been studied. Results indicate that the
process is convenient, low energy, environmentally benign and having narrow
particle size distribution of BaZrO3.
Abstract: In this study, a new nanoporous carbon was prepared by anodic oxidation treatment to remove noxic ammonia gas. The acid- and base values of the nanoporous carbon were determined by Boehm’s titration method. And, the surface properties of the carbons were investigated by XPS analysis. Also, N2/77K adsorption isotherm characteristics, including the specific surface areas and
nano/micropore volumes were studied by BET and t-plot methods, respectively. The ammonia removal efficiency was confirmed by gas-detecting tube technique. As a result, it was revealed in the case of acidic treatment on nanoporous carbons that the ammonia removal was greatly effective due to the increase of OH groups in carbon surfaces without significant changes of nanostructural properties. It
was then found that the acidic anodization of nanoporous carbons was a suitable method for the effective removal of ammonia gas, which could be attributed to the increase of acceptor-donor interactions between acidic oxygen functional groups of carbon adsorbent and basic adsorbate in an adsorbent-adsorbate system.
Abstract: X-ray photoelectron spectroscopy (XPS) has been used to characterize the Si nanocrystals (nc-Si) incorporated in SiO2 by ion implantation and subsequent thermal annealing. XPS results suggest that the as-implanted films contain a composition of a few suboxide SiOx (x<2). The dependence of XPS spectra on annealing temperature show that these suboxides decompose into SiO2 and Si nanocrystals. Due to the implanted Si+ depth profile, thermal annealing will lead to the
formation of nc-Si with different sizes corresponding to the depth. Si0 peak shifts arising from the size effect of nc-Si can be clearly observed. Photo-induced charge effect from the nc-Si has been studied in this work. The potential wells induced by nc-Si in the SiO2 band gap substantially enhance the charging effect, which causes a significant shift in Si0 and C1s core levels.
Abstract: Nano-scale Gd2O3:Eu phosphor powders were synthesized by combustion method. In this process, the grain sizes of nano-scale Gd2O3:Eu were controlled by changing the amount of citric acid. Compared with micro-scale powders obtained from co-precipitation process, XRD revealed that the lattice parameter of nano-scale powders Gd2O3:Eu decreased. Further detailed study show that the luminescent properties were related to the grain size of nano Gd2O3:Eu powders under UV excitation.
Abstract: This paper reported on the one-step synthesis of polystyrene-quantum dots (PS@QD)nanoparticles using microemulsion polymerization method. The synthesized QD and PS@QD nanoparticles were characterized by UV, fluorescence spectroscopy, transmission electron microscopy (TEM) and fluorescence microscopy. The PS@QD is highly luminescent, which have the potential to be used as fluorescent probes in biological staining and diagnostics.
Abstract: This paper presents the results of an experimental procedure where a grid is applied to the edge of a specimen and the local crack-tip displacement fields are calculated using finite element technique. Increasingly, the objective of finite element simulations is to predict the response of the mechanics of material failure are related to microstructural process that occur in the materials as a result of the loading conditions. At the same time, The influences of coating thickness, coating stiffness, and assume crack pattern on the stresses concentration between the neighbouring layers of material are evaluated. Consequently, one approach to simulating the
response of structures is to explicity model the mechanisms of damage and failure in the material.
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.
Abstract: Nanocrystalline diamond (NCD) films have been prepared by microwave plasma
chemical vapor deposition (MWCVD) from methane/nitrogen mixtures, and the influence of the gas phase composition on the basic properties of the films (composition, morphology, topography, crystallinity and bonding structure) was investigated.
Abstract: The electron field emission from carbon nanotubes on nanocrystalline diamond films was investigated. Carbon nanotubes and nano-diamond films were deposited on Si substrates by hot filament chemical vapor deposition. The experimental results showed that the carbon nanotubes on nanostructured films exhibited a lower value of the turn-on electric field than those of carbon nanotubes and nano-diamond. It was found that the turn-on field of nanotubes on nano-diamond was about 0.9V/μm, which was lower than those of carbon nanotubes and nano-diamond.
Abstract: The intrinsic stress of tetrahedral amorphous carbon film as a function of annealing
temperature is investigated. The film was deposited using the filtered cathodic vacuum arc technique and subsequently annealed at various temperatures. The stress is determined by Stoney’s equation using surface profilometry, and the microstructure is studied using atomic force microscopy, visible and ultraviolet Raman spectroscopy. It is found that as the annealing temperature increases the film stress decreases slowly up to 500 oC and then falls quickly at 600 oC.
It is interesting to note that at this temperature sp3 fraction retains while sp2 clustering begins, which contributes to the sharp decrease in the stress.