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Moudir N.,Blida University | Moulai-Mostefa N.,Blida University | Moulai-Mostefa N.,Dr. Yahia Fares University Center of Medea | Boukennous Y.,CRTSE
Particulate Science and Technology | Year: 2015

In this study we report the preparation and characterization of fine silver microparticles by simple chemical reduction of silver nitrate using two types of bases and poly(N-vinylpyrrolidone) as protective agent. The influence of silver nitrate concentration and the nature and concentration of bases, on the properties of the silver microparticles was investigated. The structural characteristics of microparticles were determined using X-ray diffraction, scanning electron microscopy, and particle distribution analysis. It was noticed that the structure and the shape of silver microparticles depend on the base nature and the concentration of silver nitrate added to the base. It was also noted the absence of agglomerates in the powder prepared with PVP. This polymer not only serves as both coordinating agent and stabilizing one, but also plays an important role in controlling the size and shape of metal particles. © 2015 Taylor and Francis Group, LLC.

Lounas A.,CRTSE | Nait Bouda A.,CDTA | Menari H.,CRTSE | Belkacem Y.,CRTSE | Gabouze N.,CRTSE
Surface Engineering | Year: 2014

Silicon etching in alkaline solutions has been employed for many years, in the fabrication of solar cells. Surface texturisation of crystalline silicon was performed by using different etching solutions. Recently, a strong oxidising reagent NaOCl has been used successfully by several authors to texture the silicon surface. In this work, the effect of the etching parameters such as solution composition on the silicon surface morphology is studied. The surface of etched samples was analysed by scanning electron microscopy (SEM), spectrophotometry and secondary ion mass spectroscopy (SIMS). The results clearly show that the presence of ethanol in the solution leads to the formation of pyramids, while its absence induces the formation of nanostructures (nanowire or nanoneedle). © 2014 Institute of Materials, Minerals and Mining.

Bouhafs D.,CRTSE | Khelifati N.,CRTSE | Kouhlane Y.,CRTSE
Acta Physica Polonica A | Year: 2016

We have investigated in this work the effect of the temperature profile during homogeneous phosphorous diffusion gettering (PDG) on multicrystalline (mc-Si) silicon p-type wafers destined for photovoltaic solar cells. Temperatures were varied from 800 °C to 950 °C with time cycle of 90 minutes. Phosphorous profile of n+p junction was measured by secondary ion mass spectroscopy (SIMS) from 0.45 μm to 2.4 μm. Chromium concentration profile measured on the same samples by SIMS shows a high accumulated concentration of Cr atoms in the gettering layer at 900 °C and 950 °C, compared to samples obtained at 800 °C and 850 °C. The effective lifetime (Teff) of minority charge carriers characterized by quasi-steady state photoconductance (QSSPC) is in correlation with these results. From the QSSPC measurements we have observed an amelioration of Teff from 7 μs before PDG to 26 μs in the samples after PDG, processed at 900 °C. This indicates the extraction of a non-negligible concentration (5 × 1014 cm-3 to 5 × 1015 cm-3) of Cr from the bulk to the surface gettering layer, as observed in the chromium SIMS profiles. A light degradation of Teff (18 μs) is observed in the samples treated at 950 °C due probably to a partial dissolution of the metallic precipitates, especially at the grain boundaries and in the dislocations vicinity. The related TCr-Impurity lifetime value of about 8.5 μs is extracted, which is the result of interstitial Cri or CriBs pairs, proving their strongest recombination activity in silicon.

Moudir N.,Blida University | Boukennous Y.,CRTSE | Moulai-Mostefa N.,Blida University | Moulai-Mostefa N.,Dr. Yahia Fares University Center of Medea | And 5 more authors.
Energy Procedia | Year: 2013

The preparation of fine silver particles is getting great attention due to their applications in electrical fields such as the fabrication of conductive pastes used in solar cell metallization. This study deals with the preparation of silver powders by a chemical reduction method using silver nitrate as a starting material, and either sodium or ammonium hydroxides as reactants, and formaldehyde as a reducing agent. The effects of ratio change between the silver nitrate and the base concentrations, on the characteristics of the silver micro particles, were examined. The physicochemical properties of the powders were evaluated using XRD, SEM, and granulometry. It was shown that the particle size and shape of the powder depend on the molar ratio of silver nitrate to base and, on the base nature. © 2013 The Authors.

Aoudj S.,CRTSE | Aoudj S.,University Blida1 | Khelifa A.,University Blida1 | Drouiche N.,CRTSE | And 2 more authors.
Chemical Engineering Journal | Year: 2015

A combined two-step EC-EF process was designed to simultaneously remove Cr(VI) and fluoride from pretreated acidic semiconductor effluents. The EC step comprises integrated reduction of chromium(VI) with coagulation of fluoride, while in the EF step, clarification takes place. In EC step a hybrid Fe-Al was used as sacrificial anode and stainless steel as cathode. Initially, the effect of anodic material on EC-EF efficiency was investigated and it was found that the combination 2Fe-2Al gives the optimum results. Most of Cr(VI) removal was ascribed to iron plates, while fluoride removal was mainly ascribed to aluminum plates. Presence of coagulants enabled the removal of suspended solids which are present in initial solution. Effects of initial pH, current intensity, anions nature, chloride concentration and initial concentration on EC-EF process efficiency using hybrid anode were studied. The behavior of the hybrid anode depends on both iron and aluminum individual properties toward pollutants. Under optimum conditions, residual concentrations of Cr(VI) and fluoride and turbidity after EC-EF were found under national discharge standards. © 2014 Elsevier B.V.

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