On the Purity of Atmospheric Glow-Discharge Plasma

Purity of the glow-discharge plasma at atmospheric pressure for surface modification applications is always debatable, since it works at ambient atmosphere. We have demonstrated on the use of optical emission spectroscopy to test the purity of this kind of plasma. The effect of gas flow pattern, nature of gas, and its flow rate on the plasma chemistry was studied. The importance of proper system design in maintaining a uniform flow of heavy and inert gases as carrier gas in atmospheric glow-discharge plasma was confirmed. The surface of a plasma-treated PET sample was analyzed using X-ray photoelectron spectroscopy to verify the studies on plasma purity done using emission spectrum

Wetting characteristics of vertically aligned graphene nanosheets

Vertically aligned graphene nanosheets (VAGNs) are a class of graphitic carbon in which few layers of graphene nanosheets are aligned perpendicular to the plane of the substrate. The change in water contact angle (from 103 degrees to 135 degrees) with VAGNs, as a function of change in the surface geometry, is analysed. Theoretical calculations and comparison with the experimental data shows that the apparent contact angle values of VAGNs are closer to that of the fully non-wetting mode or ideal Cassie mode of wetting. The ideal Cassie mode of wetting also explains the variation of the water contact angle of VAGNs with the surface morphology of the material and predicts how surface parameters can be modified to get the required wettability for a certain application of this material

Growth and characterization studies of ZnS thin films prepared by single source evaporation technique

Zinc sulfide thin films are deposited on glass substrates using thermal evaporation technique. Effect of thickness on the properties of as-deposited ZnS films is studied. ZnS films exhibited cubic structure with preferential orientation along (111) plane. All the films exhibited n-type conductivity with resistivity ranging in the order of 10(5) to 10(6) Omega-cm. The transmittance in the visible region is in the range of 80 to 89% and the band gap of the material varied from 3.65 to 3.52 eV. The as-deposited films can be used as window layer for fabrication of hetero-junction solar cell

Correlation between anodization variables and surface properties of titania nanotube arrays for dye-sensitized solar cells

The effect of anodization variables on the morphology and surface properties of oriented titania nanotube arrays (TNAs) was investigated. The arrays were synthesized using hydrofluoric acid based ethylene glycolelectrolyte. The results show that the anodization time plays a significant role in the surface properties as well as length of the nanotubes. However, the contribution of anodization potential to debris formation was found to be negligible within the investigated range of the potential. The F- ion concentration and aging of electrolyte were found to play crucial roles in the formation of ordered clean nanotubes. The studies conducted by employing these TNAs as photo-anodes for dye-sensitized solar cells (DSCs) show that the morphology variations alone alter the photovoltaic properties of DSCs to a great extent

Estimating the number density and energy distribution of electrons in a cold atmospheric plasma using optical emission spectroscopy

Cold atmospheric plasmas are generous sources of chemically active species, the reaction rates which can be predicted only if the electron number density and the electron energy distribution function are known. Here, the authors present a procedure for estimating both these parameters from the optical emission spectrum of an argon plasma. The peaks in the spectrum were curve fitted with Voigt profiles, and their widths and areas were mapped to the number density and energy distribution of electrons in the plasma, using the mathematical models for Stark broadening and Corona population, respectively. These plasma parameters were optimized to establish a good match between the simulated and the experimental peak attributes. This analysis estimated the value of the electron number density to be approximately 1.5 x 10(15) cm(-3) and the mean electron temperature to be approximately 0.37 eV in their plasma. It also predicted that the energy distribution of electrons can be closely approximated using a Maxwellian distribution. Published by the AVS

Analysis of integrated optofluidic lab-on-a-chip sensor based on refractive index and absorbance sensing

The analysis of a fully integrated optofluidic lab-on-a-chip sensor is presented in this paper. This device is comprised of collinear input and output waveguides that are separated by a microfluidic channel. When light is passed through the analyte contained in the fluidic gap, optical power loss occurs owing to absorption of light. Apart from absorption, a mode-mismatch between the input and output waveguides occurs when the light propagates through the fluidic gap. The degree of mode-mismatch and quantum of optical power loss due to absorption of light by the fluid form the basis of our analysis. This sensor can detect changes in refractive index and changes in concentration of species contained in the analyte. The sensitivity to detect minute changes depends on many parameters. The parameters that influence the sensitivity of the sensor are mode spot size, refractive index of the fluid, molar concentration of the species contained in the analyte, width of the fluidic gap, and waveguide geometry. By correlating various parameters, an optimal fluidic gap distance corresponding to a particular mode spot size that achieves the best sensitivity is determined both for refractive index and absorbance-based sensing

Atomic Defects Influenced Mechanics of II–VI Nanocrystals

Mechanical properties of nanocrystals are in fluenced by atomic defects. Here, we demonstrate the effect of planar defects on the mechanics of ZnO nanorods using atomic force microscopy, high-resolution transmission electron microscopy,and large-scale atomistic simulation. We study two different conditionally grown single nanorods. One contains extended I1-type stacking fault (SF) and another is defect free. The SF containing nanorods show buckling behaviors with reduced critical loading, whereas the other kinds show linear elastic behavior. We also studied the size dependence of elastic modulus and yield strength. The elastic modulus in both nanorods is inversely proportional to their size. Similar trend is observed for yield strength in the SF containing nanorods; however, the opposite is observed in the SF-free nanorods. This first experimental and theoretical study will guide toward the development of reliable electromechanical devices

An Investigation of Facile One-Pot Synthesis of Li2FeSiO4/C Composite for Li Ion Batteries

Li2FeSiO4 and its carbon composite are prepared by an urea-assisted combustion method. The synthesis has been carried out in different urea concentrations, namely 1 Molar (M), 2 M and 3 M urea in the cost-effective ambient atmospheric condition. The x-ray diffraction analysis confirms the orthorhombic structure of Li2FeSiO4 compounds. The urea-assisted combustion reaction enhanced the phase purity of the compound and prevented the oxidation of ferrous ions in Li2FeSiO4. The x-ray photo electron spectroscopy analysis further confirmed the reduction of Fe3+ concentration in Li2FeSiO4 while adding urea. The Li2FeSiO4 compound formation in the presence of urea occurred at a temperature < 623 K. The one-pot synthesis of Li2FeSiO4/C with the help of starch and urea in ambient atmospheric condition resulted in Li2FeSiO4 with an orthorhombic crystal structure. The carbon coating in an amorphous nature is observed and the lattice dimension values of Li2FeSiO4/C are 6.248 , 5.330 , and 5.029 . The lattice parameter has remained unchanged with carbon addition. The addition of 5% carbon to Li2FeSiO4 improves the electrical conductivity and lithium diffusion coefficient to 7.24 x 10(-4) S cm(-1) and 5.54 x 10(-6) cm(2), respectively. The coulombic efficiency and capacity retention after 50 cycles of Li2FeSiO4/C composite are around 83% and 95%, respectively

Nanometric chemical decomposition of infertile Himalayan soils from Uttarakhand

We present the nanometric chemical decomposition of Himalayan agricultural soils. The motivation to use this state-of-the-art material characterisation in the soil is to reduce the testing cost while increasing the efficiency of the characterisation. In India, a bulk volume of soil is still required for the characterisation of agricultural soil. The fertility of micronutrient contents and crop supply capacity vary greatly depending on soil types, crop types, ecology, and agroclimatic variability. Since total levels of micronutrients are rarely predictive of the availability of a nutrient to plants, knowledge of the differences in soil micronutrients that are available to plants is essential for the sensible management of micronutrient fertility and toxicity. In the state of Uttarakhand, low levels of micro-nutrients in the soil are frighteningly common, and this issue is made worse by the fact that many current cultivars of important crops are extremely vulnerable to low mineral levels. These baseline results are to be used to inform local farmers about the potential remedies, costs, and consequential benefits and durability. We intend not to present a generalized or generalized solution. Therefore, we limit our soil sample collections to five arc minutes (8.6 square kilometers) and document variations and heterogeneity in the chemical components of the soil. In this study, we used scanning electron microscopy to chemically deconstruct the barren Himalayan soils from Uttarakhand. Aluminium, carbon, oxygen, and silicon were identified as the primary elements that contributed more than 5% of the total weight and atomic percentage. Other elements include less than 4% of iron, titanium, nitrogen, sodium, magnesium, chloride, phosphorus, sulfur, potassium, and calcium