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Este trabajo se propone avanzar en la comprensión de los procesos históricos de pintado del sitio arqueológico de Oyola (Sierra El Alto-Ancasti, Catamarca, Argentina). En particular, se evalúan similitudes y diferencias en la composición material de las mezclas pigmentarias para entrever la existencia de antiguas recetas pictóricas en la confección de las pinturas rupestres negras. Para ello se realizaron análisis microestratigráficos de 28 motivos mediante microscopía electrónica de barrido con análisis elemental por espectroscopía dispersiva en energía de rayos X (MEB-EDS), y microespectroscopía Raman (RS). Su estudio comparativo señaló el uso alternativo de dos pigmentos negros (carbón vegetal y óxidos de manganeso) combinados, en algunos casos, con un aditivo (sulfato de calcio). De esta forma, fue posible conocer ciertos aspectos de las recetas pictóricas que orientaron la preparación de las mezclas pigmentarias negras, aproximándonos a algunas de las tradiciones y saberes retomados. Para alcanzar una comprensión histórica de dichas recetas, se evaluó la distribución espacial, temporal y algunas características formales de los motivos rupestres realizados con ellas. Al no identificarse tendencias claras, se propone una definición menos normativa de receta pictórica que resalta los aspectos compartidos entre distintos episodios de pintado sin perder de vista las posibilidades creativas de cada evento.
Zn(S,O,OH) Chemical Bath Deposited (CBD) remains one of the most studied Cd-free buffer layer for replacing the CBD-CdS buffer layer in a Cu(In,Ga)Se2-based (CIGSe) solar cells and has already demonstrated its potential to lead to high-efficiencies. However, in order to further increase the deposition rate of the Zn(S,O,OH) layer during the CBD, the inclusion of additives can be a reasonable strategy, as long as the efficiencies of solar cells are maintained. The aim of this work is to understand the effect of the introduction of additives such as hydrogen peroxide (H2O2), H2O2+ethanolamine (C2H7NO) and H2O2+tri-sodium citrate (Na3C6H5O7) during CBD on the deposition mechanism, the growth rate and the quality of the buffer layer. It has been shown that the combined use of H2O2 and citrate in the bath formulation allows the deposition of Zn(S,O,OH) via a mix of “ion-by-ion” and “cluster-by-cluster” mechanisms that have good properties as buffer layers leading to high efficiency solar cells.
Polyurethane catheters made of Pellethane 2363-80AE® were treated with a low temperature plasma developed for the decontamination of reusable polymer devices in hospitals. We investigated the modifications of the polymer surface by studying the topographic modifications, the chemical modifications, and their consequences on the wettability and bacterial adhesion. This study showed that plasma treatment modified the topography and grafted oxygen and nitrogen species onto the surface, resulting in an increase in the surface polarity. This effect could be correlated to the number of nitrogen atoms interacting with the surface. Moreover, this study demonstrated the significance of multiscale heterogeneities, and the complexity of industrial medical devices made from polymers. Their surface can be heterogeneous, and they contain additives that can migrate and change the surface composition.
Hydrogen (deuterium used as tracer) diffusion experiments were performed on undoped and boron doped diamond films ([B] = 1019and 1020 cm−3) grown by plasma CVD or hot-filament assisted CVD. The samples were exposed either to a radiofrequency plasma or a microwave plasma at different temperatures between 400°C and 900°C. The deuterium profiles were analysed by secondary ion mass spectrometry (SIMS). The deuterium diffusion was explained mainly in term of trapping on intergranular defects. The passivation of boron acceptors, by B-D complex formation in the deuterium diffused superficial layers of the diamond films, was followed by electrochemical and mercury probe capacitance measurements. The results suggest a strong decrease of the free carrier density, which is in accordance with passivation of free carriers by deuterium trapping on dopant.
This paper presents optimization studies on the formation of cadmium free buffer layers for high efficiency copper indium diselenide (CIGS) thin film solar cells using a vapor phase route. Indium sulfide layers have been deposited on CIGS substrates by Atomic Layer Deposition (ALD) at substrate temperatures between 140 and 260 °C using indium acetylacetonate and hydrogen sulfide precursors. The parametric study of the deposition temperature shows an optimal value at about 220°C, leading to an efficiency of 16.4 % which is a technological breakthrough. The analysis of the device shows that indium sulfide layers give an improvement of the blue response of the cells as compared a standard CdS processed cell, due to a high apparent band gap (2.7-2.8 eV), higher open circuit voltages (up to 665 mV) and fill factor (78 %). This denotes high interface quality of the system. Atomic diffusion processes of sodium and copper in the buffer layer are evidenced.
Chemistry of co-evaporated CIGS surfaces submitted to chemical treatments relevant to fabrication steps were investigated by XPS and admittance spectroscopy. A Se XPS signal specific of the CIGS surfaces was identified. Surface states seen by Admittance and surface chemistry are seen to change significantly during the elaboration steps. Consequences for device elaboration are briefly discussed.
We study the optical behavior of Au-TiO2 thin cermet films, the gold volume fraction of which is
varied over the range 10−3 to 8 × 10−2. In this low concentration range, it is mainly governed by the
metallic particles size, which very much depends on the deposition substrate temperature and the
annealing time and temperature. The samples structure and morphology are characterized by several
complementary techniques. Spectrophotometric measurements at quasi-normal incidence have been
performed in visible and near infrared regions. Using a short pulse Nd:YAG laser, we also look for nonlinear optical behavior due to the enhancement of the electromagnetic field close to the surface plasmon
resonance of the metallic grains.
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