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241.
Franck Bassani Priyanka Periwal Bassem Salem Nicolas Chevalier Denis Mariolle Guillaume Audoit Pascal Gentile Thierry Baron 《固体物理学:研究快报》2014,8(4):312-316
Silicon nanowires (SiNWs) with axial doping junctions were synthesized via the Au‐catalyzed vapor–liquid–solid growth method with the use of HCl. In this work, dopant profiling from three axially doped SiNWs with p–i, p–n and n–i–p junctions were investigated using both scanning electron microscopy (SEM) and scanning capacitance microscopy (SCM). It turns out that observed doping contrasts in SEM are also affected by the surface roughness and sample charging. In contrast, SCM allows us to delineate with sub‐10 nm resolution the electrical junctions and provides a relative value of the doping concentration in each segment of the NW. SCM clearly evidences the expected doping regions within these SiNWs thanks to the addition of HCl during the growth that strongly prevents shell overgrowth. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
242.
Nadine Eckstein Rodolphe Decourt Bernard Chevalier 《Journal of solid state chemistry》2011,184(4):778-785
A selection of mixed conducting silver chalcogenide halides of the general formula Ag5Q2X with Q=sulfur, selenium and tellurium and X=chlorine and bromine has been investigated due to their thermoelectric properties. Recently, the ternary counterpart Ag5Te2Cl showed a defined d10-d10 interaction in the disordered cation substructure at elevated temperatures where Ag5Te2Cl is present in its high temperature α-phase. A significant drop of the thermal diffusivity has been observed during the β−α phase transition reducing the values from 0.12 close to 0.08 mm2 s−1. At the same transition the thermopower reacts on the increasing silver mobility and jumps towards less negative values.Thermal conductivities, thermopower and thermal diffusivity of selected compounds with various grades of anion substitution in Ag5Q2X were determined around the silver-order/disorder β−α phase transition. A formation of attractive interactions could be observed for selenium substituted phases while no effect was detected for bromide and sulfide samples. Depending on the grade and type of substitution the thermopower changes significantly at and after the β−α phase transition. Thermal conductivities are low reaching values around 0.2-0.3 W m−1 K−1 at 299 K. Partial anion exchange can substantially tune the thermoelectric properties in Ag5Q2X phases. 相似文献
243.
Designs, Codes and Cryptography - 相似文献
244.
Film formation with latex particles 总被引:2,自引:0,他引:2
Y. Chevalier C. Pichot C. Graillat M. Joanicot K. Wong J. Maquet P. Lindner B. Cabane 《Colloid and polymer science》1992,270(8):806-821
The coalescence of latex particles is investigated through small-angle neutron scattering and electron microscopy. The particles are made of a soft polymeric core protected by a hydrophilic membrane, and they are dispersed in water. This dispersion is spread on a substrate, and water is removed to form a dry film. As the membranes of neighboring particles come into contact, they may break up to allow fusion of the particle cores. This is found to occur when the membranes are made of short-chain surfactant molecules; then all hydrophilic material is expelled to the film surface or to large isolated lumps. Alternatively, the membranes may remain until the film is completely dry; this is found to occur when they are made of hydrophilic polymers which are grafted onto the core. Hence, the fusion of particles is controlled by the connectivity of membranes.This work used the neutron beams of ILL in Grenoble and LLB in Saclay 相似文献
245.
Protein refolding at high concentrations always leads to aggregation, which limits commercial application. An ion-exchange chromatography process with gradient changes in urea concentration and pH was developed to refold denatured lysozyme at high concentration. After adsorption of the denatured protein onto an ion-exchange medium, elution was carried out in combination with a gentle decrease in urea concentration and elevation of pH. Protein would gradually refold along the column with high activity yield. Denatured and reduced lysozyme at 40 mg/ml was loaded into a column filled with SP Sepharose Fast Flow, resulting in 95% activity recovery and 98% mass yield within a short period of time. 相似文献
246.
247.
K. Noble A.B. Seddon M.L. Turner P. Chevalier D.L. Ou 《Journal of Sol-Gel Science and Technology》2003,26(1-3):419-423
Porous hybrid materials have been fabricated by sol-gel processing of tetraethoxysilane (TEOS) and 1,3,5,7-tetramethyl-tetrakis(ethyltriethoxysilane)-cyclotetrasiloxane (1) in the presence of the cationic surfactant, cetyltrimethylammonium bromide (CTAB). The chemical and physical properties of these materials have been analysed by FT-IR spectroscopy, solid state 29Si NMR spectroscopy, powder X-ray diffraction and nitrogen adsorption-desorption studies. FT-IR spectroscopy established that the CTAB surfactant can be extracted from a crushed gel using ethanol as a solvent. Solid state 29Si NMR spectroscopy showed the presence of D, T and Q species as expected from the structure of the precursors. Broad bands observed for the D units at –18 ppm and the T units at –63 ppm suggested that the cyclotetrasiloxane was held in a rigid environment and bound to the Q species of the silica matrix derived from the TEOS. NMR spectroscopy confirmed that solvent extraction resulted in further condensation of the silica matrix. Powder X-ray diffraction indicated that the materials possess short-range order and small domain sizes, as shown by broad diffraction peaks. The condensation induced by solvent extraction led to a decrease in the lattice and domain size of the samples, generally resulting in a less ordered material. Nitrogen adsorption-desorption isotherms were typical of microporous materials with pore diameters of 18 Å and a narrow size distribution. 相似文献
248.
Characterisation of different inulin samples by DSC: Influence of polymerisation degree on melting temperature 总被引:1,自引:0,他引:1
Blecker C. Chevalier J.-P. Fougnies C. Van Herck J.-C. Deroanne C. Paquot M. 《Journal of Thermal Analysis and Calorimetry》2003,71(1):215-224
Melting behaviour of powder inulin has been studied by differential scanning calorimetry. DSC curves show two endothermic peaks, relative to water elimination and to inulin melting, respectively. The second peak is dependent on inulin type and a shift to a higher temperature is observed with increasing average polymerisation degree (DP) of the sample. For similar crystallinity index, linear relations have been underlined and so predicting inulin mean DP can be done by DSC analysis. The study shows that a relatively high heating rate (25°C min–1) can be used and brings a supplementary interest by an important reduction of analysis time.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
249.
250.