Effect of oleylamine on microwave synthesized Cu2ZnSnS4 nanocrystals for photovoltaic junctions

Cu₂ZnSnS₄ (CZTS) with its high absorption coefficient, optimal band gap, and non‐toxic, earth‐abundant elemental constituents is a promising absorber material for low cost and high‐performance photovoltaics. CZTS nanocrystals were prepared by microwave‐assisted thermolysis method using ethylene glycol solvent in a rapid and energy efficient process with and without oleylamine as additional capping agent. X‐ray diffraction data indicated crystallite sizes of 5 and 12 nm respectively. Raman spectra showed the formation of pure Cu₂ZnSnS₄ phase in both cases. With pure ethylene glycol solvent, field emission scanning electron microscopy images showed particle sizes around 250 nm, ultraviolet‐visible absorption data gave optical band gap of 1.52 eV and Hall measurements yielded electrical resistivity ~70 Ωcm, carrier density ~2.7 × 10¹⁶/cm³, and hole mobility ~3.24 cm²/Vs. Adding optimum amount of oleylamine reduced the particle size to 100 nm and lower. The optical band gap reduced to 1.48 eV and electrical resistivity, carrier concentration, and Hall mobility changed to ~5.9 × 10⁴ Ωcm, 2.57 × 10¹²/cm³, and 4.1 cm²/Vs respectively. A knee voltage of ~0.8 V shown by CZTS/CdS p‐n junction indicated that a good V_oc can be expected from a solar cell constructed with the CZTS nanocrystals as absorber layer.     

Simulation of temperature distribution by finite element analysis on different components of the EXAFS beamline at INDUS-II synchrotron source

An extended X-ray absorption fine structure (EXAFS) beamline is being developed for the INDUS-II synchrotron source. Several optical and mechanical components of the beamline are exposed to high intensity synchrotron radiation while in operation. The temperature rise on different components of the beamline on exposure to the synchrotron beam has been simulated by finite element analysis. Design of the cooling mechanism for each of these components has been carried out and estimation of the temperature rise has also been done incorporating the cooling mechanism.     

Electron field emission from <Emphasis Type="Italic">sp</Emphasis><Superscript>2</Superscript>-induced insulating to metallic behaviour of amorphous carbon (<Emphasis Type="Italic">a</Emphasis>-C) films

The influence of concentration and size of sp ² cluster on the transport properties and electron field emissions of amorphous carbon films have been investigated. The observed insulating to metallic behaviour from reduced activation energy derived from transport measurement and threshold field for electron emission of a-C films can be explained in terms of improvements in the connectivity between sp ² clusters. The connectivity is resulted by the cluster concentration and size. The concentration and size of sp ² content cluster is regulated by the coalescence of carbon globules into clusters, which evolves with deposition conditions.     

Quantification of organophosphate insecticides and herbicides in vegetable samples using the “Quick Easy Cheap Effective Rugged and Safe” (QuEChERS) method and a high-performance liquid chromatography-electrospray ionisation-mass spectrometry (LC-MS/MS) technique

A Quick Easy Cheap Effective Rugged and Safe (QuEchERS) extraction was developed and followed by selective analysis using a liquid chromatography-mass spectrometry method for the quantification of eighteen pesticides in vegetable samples. This method was accurate (?99.5%), and it exhibited limits of detection and quantification values in the 0.006-0.091 and 0.020-0.314 μg kg⁻¹ ranges, respectively. Furthermore, the coefficients of variations (?0.9999) were less than 1% at the low μg kg⁻¹ end of the method. Mean recoveries ranged between 94% and 102%, and relative standard deviations were below 10%. Based on these results, the methodology was proven to be highly efficient, robust, and suitable for monitoring the maximum residue limits (MRL) compliance of a wide range of commodity/pesticide combination. This method was successfully applied to the analysis of vegetable samples that were collected from different government farmers’ markets and street shops in urban areas. The presence of target pesticides was found in the range of 0.016 and 50.85 μg kg⁻¹.     

Synthesis and characterisation of starch/agar nanocomposite films for food packaging application

In the present work cassava starch/agar Ag and ZnO nanocomposite films were prepared by the solution casting method. The structural, physical and antimicrobial properties of the nanocomposite films were studied as a function of the concentration of Ag and ZnO nanoparticles. The results of the thermogravimetric analysis showed 8–15% degradation of both the nanocomposite films at 150°C endorsing the thermal stability of the films. Scanning electron microscopic analysis reveals the uniform blending of Ag and ZnO nanoparticles with a starch/agar matrix with tiny waves like appearance on the surface. The incorporation of Ag and ZnO nanoparticles in the film was found to reduce the moisture content, water solubility and water vapour permeability with increase in the concentration of Ag and ZnO nanoparticles. The growth kinetics study of Pseudomonas aeruginosa and Staphylococcus aureus in the presence of Ag and ZnO blended nanocomposite films showed promising results especially against Gram‐negative P. aeruginosa. Thus, the film synthesised in the present study bears the potential to be used as active packaging material to prevent food from bacterial contamination and spoilage.Inspec keywords: casting, microorganisms, scanning electron microscopy, nanoparticles, food preservation, solubility, thermal analysis, zinc compounds, food processing industry, food products, thermal stability, permeability, antibacterial activity, food packaging, contaminationOther keywords: water vapour permeability, food packaging, solution casting method, structural properties, physical properties, antimicrobial properties, water solubility, agar nanocomposite film, starch nanocomposite film, Pseudomonas aeruginosa, Staphylococcus aureus, bacterial contamination prevention, spoilage prevention, scanning electron microscopic analysis, thermogravimetric analysis, temperature 150.0 degC, Ag, ZnO     

印度Ispat CSP工厂生产优质热轧卷

1998年,印度Ispat公司开始投产CSP生产线(图1).这个生产线原计划年产300万t热轧卷,年产210万t高炉提供铁水.Midren装置年产160万吨海绵铁.