This paper discusses the use of Box Behnken design (BBD) approach to plan the experiments for turning the yield of CVD, thickness and layer number of graphene sheets with an overall objective of optimizing the process to provide higher graphene production volume, fewer layers and thinness structure of graphene. BBD is having the maximum efficiency for an experiment involving four factors such a...

We report a combined experimental and modeling study of microwave-activated dilute CH4/N2/H2 plasmas, as used for chemical vapor deposition (CVD) of diamond, under very similar conditions to previous studies of CH4/H2, CH4/H2/Ar, and N2/H2 gas mixtures. Using cavity ring-down spectroscopy, absolute column densities of CH(X, v = 0), CN(X, v = 0), and NH(X, v = 0) radicals in the hot plasma have ...

chemical vapor deposition (cvd) is one of the most important methods for producing carbon nanotubes (cnts). in this research, a numerical model, based on finite volume method, is investigated. the applied method solves the conservation of mass, momentum, energy and species transport equations with aid of ideal gas law. using this model, the growth rate and thickness uniformity of produced cnts,...

Very short arrays of continuous single-wall carbon nanotubes (SWNTs) are grown incrementally in steps as small as 25 nm using pulsed chemical vapor deposition (CVD). In-situ optical extinction measurements indicate that over 98% of the nanotubes reinitiate growth on successive gas pulses, and high-resolution transmission electron microscopy (HR-TEM) images show that the SWNTs do not exhibit seg...

Stationary phases that provide high resolutions and are stable at high temperatures are of significant importance in chromatographic analysis. Carbon nanotubes (CNTs) are known to have high thermal and mechanical stability and have the potential to be high-performance separation media that utilize the nanoscale interactions. Here, we report the first application of self-assembled CNTs in long c...

Gas-phase silver nanoparticles were coated with silicon dioxide (SiO2) by photoinduced chemical vapor deposition (photo-CVD). Silver nanoparticles, produced by inert gas condensation, and a SiO2 precursor, tetraethylorthosilicate (TEOS), were exposed to vacuum ultraviolet (VUV) radiation at atmospheric pressure and varying temperatures. The VUV photons dissociate the TEOS precursor, initiating ...

AIMS Dietary fats are routinely considered key determinants of cardiovascular risk, yet the scientific basis of this association has never been demonstrated using objective measures of fat intakes in a large prospective study in a general population. METHODS AND RESULTS Adipose tissue was taken from 3944 participants, predominantly aged 40-59 years, in Scotland, 1984-87. Percentages of indivi...

Simple kinetic models of carbon nanotube growth have been able to successfully link together many experimental parameters involved in the growth of carbon nanotubes for practical applications including the prediction of growth rates, terminal lengths, number of walls, activation energies, and their dependences on the growth environment. The implications of recent experiments utilizing in situ m...

Silicon microspheres produced in gas-phase by hot-wall CVD offer unique quality in terms of sphericity, surface smoothness, and size. However, the spheres produced are polydisperse in size, which typically range from 0.5 μm to 5 μm. In this work we show through experiments and calculations that thermophoretic forces arising from strong temperature gradients inside the reactor volume effectively...

Abstract: In this study, carbon nanotubes (CNTs) were grown directly in the pores of micro porous pyrex membranesand consequently ceramic membranes with very fine pores and high porosity were achieved. Our experiment was donein two stages. Initially cobalt powder with different percent was homogeneously mixed with pyrex powder. In order toproduce row membranes, each of these mixtures were compa...