Ces travaux contribuent à l'amélioration du procédé de synthèse de dispositifs photovoltaïques en couches minces à base d'alliage Cu(In, Ga)(S, Se)2. Dans cette étude, l'étape d'électrodépôt de Cu-In-Se a été étudiée. Le principal enjeux de cette thèse était l'optimisation de la distribution de courant pendant le procédé d'électrodépôt. La distribution de courant, principalement contrôlée par les conditions hydrodynamiques, est optimisée pour deux types d'électrolyseurs : l'électrolyseur à peigne, qui est le système d'agitation standard à l'IRDEP, et un électrolyseur alternatif à jets. Pour l'optimisation des conditions d'agitations, un système électrochimique (Cu-Ni) a été développé et utilisé pour modéliser les phénomènes de transport de matière pendant le procédé d'électrodépôt de Cu-In-Se. Pour les deux systèmes, l'effet de la variation des paramètres géométriques des électrolyseurs a été étudié, et un paramètre de contrôle a été développé. Le contrôle des conditions hydrodynamiques par le biais de ce paramètre permet d'augmenter l'homogénéité des électrodépôts.

Les techniques d'élaboration par déformation plastique intense permettent d'obtenir des matériaux nanostructurés à l'état massif. La grande quantité de défauts (dislocations, lacunes,...) peut donner lieur à des transformations de phases hors équilibre. L'objectif de ce travail à été de produire par HPT (high pressure torsion) une solution solide hors équilibre à partir du système modèle Cu-Fe et de comprendre les mécanismes physiques à l'origine de sa formation. Le matériau initial est un nanocomposite filamentaire Cu-cfc/Fe-α. Des tranches de ce composite ont été déformées par HPT pour une large gamme de taux de déformation. Le matériau obtenu a été caractérisé par DRX, spectroscopie Mössbauer, MET et sonde atomique tomographique. Les filaments de ferrite sont dans une premier temps amincis jusqu'à environ 5nm. Le mélange forcé commence alors par diffusion de Fe dans Cu-cfc pour enfin aboutir à une solution solide homogène de Fe dans Cu-cfc. A la vue des données, les dislocations et le cisaillement répété des interfaces ne peuvent pas expliquer la formation du mélange forcé. Celle-ci est attribuée à la diffusion accélérée par les lacunes en excès.

<p>In this thesis the magnetic and structural properties of ultra-thin 3d transition metals films have been investigated, in particular Fe, Ni and Co films. X-ray Magnetic Circular Dichroism (XMCD) has provided element specific spin (m_s ) and orbital (m_l ) moments per atom by utilizing the magneto optic sum-rules. Element specific hysteresis curves have been measured by means of X-ray Resonant Magnetic Scattering (XRMS), and the local crystallographic structure has been investigated using Extended X-ray Absorption Fine Structure (EXAFS). </p><p>By performing XMCD on Fe/Ag(100) we observe a spin reorientation from in-plane to out-of-plane as the Fe thickness is lowered. At temperatures below 300K it occurs around 5-7 mono layers (ML) of Fe. While reorienting the magnetization out-of-plane the orbital moment increases with 125% but only a minor increase (5%) of the spin moment is observed. Extended X-ray Absorption Fine Structure (EXAFS) measurements indicate that films 6 ML and thicker have a bulk-like bcc structure. For the thin out-of-plane films, the local crystallographic structure is more complicated. </p><p>The spin reorientation of the Au/Co/Au tri-layer system has been studied as a function of temperature, Co layer and Au cap thickness. An unexpected behavior of the orbital moment upon spin reorientation is found in these systems. An ex-situ prepared sample shows a smooth spin reorientation from an in-plane to an out-of-plane easy magnetization direction as the temperature is lowered from 300K to 200K. In-situ prepared samples have also been investigated and a novel phase diagram has been identified. The Au/Co interface has been explored during the Au capping by means of photoemission measurements. </p><p>In the bi- and tri-layer system of Fe and Ni we have been able to manipulate the spin reorientation by varying the Fe and Ni thickness. A novel non-collinear interlayer exchange interaction for 3d ferro magnets in direct contact has been discovered for a set of samples. This exchange interaction is found to be strongly dependant on the preparation conditions.</p>

Résumé: Parmi les aspects les plus passionnants de l'étude du développement dans les sociétés modernes on trouve celui de la dimension culturelle de la modernité et, plus spécialement, les différents courants et les propositions élaborées sur le terrain conflictuel des relations interethniques. Historiquement les sociétés latino-américaines ont vécu une relation complexe, tendue et irrésolue à l'égard de leurs populations indigènes. D'innombrables courants idéologiques et politiques se sont succédé à travers le temps sans résoudre cette tension, résultat de l'intégration de différentes cultures dans un projet de développement social commun. Même en tenant compte de la grande variété des réalités sociales, démographiques, économiques et politiques que la population indigène a expérimentées dans cette région, l'on constate une sorte de résurgence générale de l'identité indigène dans le milieu urbain, ce qui est mis en évidence tant au travers de données de type quantitatif que qualitatif. Ce processus de ré articulation indigène dans la ville a stimulé un nouveau débat ainsi qu'une série de questionnements à l'égard des processus identitaires émergeant au sein de ces sociétés. Partant de cette constatation empirique, ce travail a été orienté vers la recherche de certaines réponses à ces questions, analysant les éléments théoriques relevant du thème central de cette étude, c'est-à-dire, l'identité ethnique dans le cas des indigènes mapuche du Chili. Resumen: Entre los procesos más interesantes del estudio del desarrollo en las sociedades modernas se encuentra el de la dimension cultural de la modernidad, y más especificamente, el terreno conflictivo de las relaciones inter éntnicas. Históricamente, las sociedades latinoamericanas han vivido una relación compleja, tensa e irresuelta frente a sus poblaciones indígenas. Numerosas corrientes ideológicas y políticas se han sudedido a través del tiempo sin lograr resolver satisfactoriamente dicha tensión, resultado, entre otros factores, de la integración forzada de diferentes culturas en un proyecto de desarrollo social comun. Incluso considerando la gran variedad de realidades sociales, demográficas, económicas y políticas que la población indígena presenta en la región, se puede constatar en el último tiempo una suerte de resurgimiento general de la identidad indígena en el medio urbano, evidenciado tanto por datos cuantitativos, como cualitativos. Partiendo de esta constatación empírica, este documento se orienta a la búsqueda de respuestas a dichos procesos, analizando elementos teóricos relevantes y pertinentes al tema central y profundizando con el estudio de casos propuesto, es decir, la identidad étnica de los indígenas mapuche en Chile. Summary: Among the most interesting processes in developmental studies of modern societies we find the cultural dimension of modernity and, more specifically, the conflictive domain of inter ethnical relations. Latin American societies have historically lived a very complex, tense and unresolved relation with their indigenous peoples. Uncountable ideological and political schools of thought have tried to resolve this tension, consequence of the imposition of a common social project, without success. Even considering the vast variety of social, demographic, economic and political realities the indigenous peoples present in the region, lately a sort of re emergency of the indigenous identity in urban areas has taken place. Starting from this empirical evidence, this document searches for answers to explain such identity processes through a rich articulation between the analysis of relevant theoretic elements and the in-depth study case proposed which is the mapuche indigenous population in Chile.

Dynamic Mechanical Analyzer (DMA) was used to study the frequency dependence of storage and loss modulus of amorphous Pd₄₀Ni₁₀Cu₃₀P₂₀ alloy over a broad frequency range around its glass transition temperature. The amorphous samples were subjected to two testing conditions: constant frequency with continuous heating and isothermal with frequency sweep. The storage modulus E′ exhibited a sigmoidal change from about 90 GPa to a low value of about 0 GPa over the glass transition region. The loss modulus, E″, was characterized by an asymmetrical peak with a smaller slope at the low temperature side than at the high temperature side upon heating. These changes in moduli were associated with mechanical relaxation due to atomic motion. Similar results were also obtained under isothermal condition. The Kohrausch-Williams-Watts function was used to fit the data obtained under the isothermal condition. The peak frequencies obtained were then fitted to the VFT equation and the scaling law equation. / Singapore-MIT Alliance (SMA)

The use of solar cells for energy production has indeed a bright future. Reduction of cost for fabrication along with increased efficiency are key features for a market boom, both achieved as a result of increased knowledge of the technology. Especially the thin film solar cell technology with absorbers made of Cu(In,Ga)Se2 (CIGS) is promising since it has proven high power conversion efficiency in combination with a true potential for low cost fabrication. In this thesis different recipes for fabrication of the Cu(In,Ga)Se2 absorber layer have been studied. The deposition technique used has been co-evaporation from elemental sources. For all depositions the substrate has been heated to a constant temperature of 500 ºC in order for the growing absorber to form a chalcopyrite phase, necessary for the photovoltaic functionality. The selenium has been evaporated such to always be in excess during depositions whereas the metal ratio Cu/(In+Ga) has been varied according to different recipes but always to be less than one at the end of the process. In the work emphasis has been on the radiative properties of the CIGS film during growth. The substrate heater has been temperature controlled to maintain the constant set temperature of the substrate, regardless of varying emitted power caused by changing surface emissivity. Depending on the growth conditions the emissivity of the growing film is changing, leading to a readable variation in the electrical power to the substrate heater. Since the thermal radiation from the substrate during growth has been of central focus, this has been studied in detail. For this reason the substrate has been treated as an optical stack composed of glass/Mo/Cu(In,Ga)Se2/CuxSe which determine the thermally radiated power by its emissivity. An optical model has been adopted to simulate the emissivity of the stack. In order to use the model, the optical constants for Cu(In,Ga)Se2 and CuxSe have been derived for the wavelength interval 2 μm to 20 μm. The simulation of the emissivity of the stack during CIGS growth agreed well with what has been seen for actual growth. Features of the OP-signal could hereby be explained as a result of film thickness of Cu(In,Ga)Se2 and CuxSe respectively. This is an important knowledge for an efficient fabrication in large scale.

No description available.

Processing of nanostructured WC-Co and W-Co powders,modelling of Fe-Mn-Si alloy, swelling of Fe-Cu alloy, andmechanical properties and sintering of Fe-Mn-Si steels havebeen studied in the present thesis. W-Co precursors made by chemical synthesis were used toproduce nanostructured WCCo and W-Co powders by calcination,reduction and carburization. The phase constituents in thecalcined powders depend on temperature and atmospheres. Cobaltcan accelerate the reduction rate of the W-Co precursors as acatalyst, and cobalt influences the formation of intermediatephases during the reduction of the precursors. The ratio of carbon monoxide to carbon dioxide controlscarburization process, gives different intermediate phases andcarburization rates. There exist several intermediate phases: W6Co6C, W3Co3C, W2C due to varying carbon monoxide content in thecarburization gases. Nanostructured WC-Co powders with aparticle size of 20-50 nm have been obtained. The effect of silicon content on the particle sizedistribution of milled Fe-Mn-Si master alloy powders is muchmore significant than that of manganese content. A finer finalparticle size can be obtained in the alloy powders with highersilicon compositions. Long time milling results in theagglomeration of small particles. The grinding process can bedescribed using classic batch grinding equation based on thepopulation balance model. A swelling model for Fe-Cu alloyssintered at the temperatures above the melting point of copperhas been established based on the penetration mechanism. In themodel, the particle coordination number and heating rate wereused to express the porosity and the thickness of the diffusionlayers between iron and copper particles respectively. The effects of sintering temperature and time on theproperties of sintered steels have been studied. Fe-Mn-Simaster alloys made by cast-milling, atomizing, and acombination of atomization and milling have been covered. Themilled, and atomizationmilled alloy steels showed goodmechanical properties with small dimensional change. Transientliquid phase of the Fe-Mn-Si alloys accelerates densification,and offer fast diffusion of alloying elements. The addition ofa small amount of Fe-Mn-Si master alloy to Astaloy 85Mo powdercan lead to high strength with zero dimensional change. <b>Key words:</b>Processing; Modelling; Nanostructured powder;WC-Co; W-Co; Calcination; Reduction; Carburization; Particlesize; Sintered steel; Fe-Cu alloy; Swelling; Fe-Mn-Si masteralloy; Mechanical properties; Sintering parameters.

Joining of electronic components onto the circuit boards is done by soldering operation, during production of all electronic devices. In many countries, including Turkey, traditionally used tin-lead (Sn-Pb) solder alloys have been restricted to be used in consumer electronics appliances because of the toxic effects of lead (Pb) within these alloys. Tin-silver-copper (Sn-Ag-Cu) based alloys have been developed as the most promising candidate that can replace the Sn-Pb alloys. However, various problems have emerged with the increasing trend in use of Sn-Ag-Cu solder alloys in electronics industry, namely large intermetallic compound formation, low wettability and thermal shock resistance. Many researches have been done in the past decade to overcome these problems. The solutions are based on changing the undercooling of the solder alloy / which was determined to be done by either changing the composition of the solder alloy by micro-alloying or changing the cooling rate during soldering operation. In this thesis study Sn-3.5Ag-0.9Cu (wt. %) lead-free solder having the eutectic composition, was micro-alloyed with additions of aluminum (Al), iron (Fe) and titanium (Ti). Experimental results were compared with commercially available near-eutectic Sn-40Pb (wt. %) solder, a commercially available Sn-3.0Ag-0.5Cu (wt. %) solder and also eutectic Sn-3.5Ag.0.9Cu (wt. %) and near-eutectic Sn-3.7Ag-0.9Cu (wt. %) solders that were produced for this thesis study. In the first stage of the study, the effects of 0.05 wt. % of Al, Fe and Ti micro-alloying were investigated. When preliminary results of mechanical and thermal test were compared, Fe was found to make positive effect on shear strength and undercooling. Further research was carried out to establish a relationship between the Fe compositions and solder properties. Therefore, 0.01, 0.03, 0.07 and 0.1 wt. % Fe additions were also studied and results were reported. 0.01 wt. % and 0.07 wt. % Fe added solders were found to have a smaller undercooling, resulting with dispersed intermetallic compound (IMC) and thus has highest shear strength. Different cooling rates / 0.017, 0.17 and 1.7 &deg / C/sec were applied to solder-copper joints and microstructures were investigated. Large IMC-free microstructure was achieved by 0.01 wt. % Fe micro-alloyed solder, which was cooled with 1.7 &deg / C/sec rate. Wetting of copper substrate was found to be improved by additions of Al, Fe and Ti compared to alloy with eutectic composition of Sn-Ag-Cu alloy. Selected SAC+X alloys have been subjected to thermal shock experiments for crack formation analysis on the copper substrate-solder joints. The results showed that SAC+0.05Al solder has the higher thermal shock resistance, which no cracks were observed after 1500 cycles of thermal shock. In order to understand the insights of SAC performance, some of the lead-free solders were applied onto printed circuit boards for thermal shock resistance test. These results have indicate that the cracking may occur after thermal shock cycles due to process conditions of soldering operation (i.e. cooing rate), independent of the solder alloy composition.

Printed Circuit Board (PCB) industry is one of the two major Integrated Circuit (IC) part manufacturing industries in Taiwan, but it derives many environmental problems because large amount of chemicals and special materials are used in its process, especially copper sludge generated from wastewater treatment. Although the heavy metal sludge can be treated by solidification, heavy metals contained in the sludge may still be leached out due to longtime exposure to acid rain. Therefore, there are urgent needs of research and development of technologies regarding how to reduce both quantity and volume of the hazardous heavy metal sludge and how to recycle the valuable heavy metals. Acid leaching method, chemical exchange method and ferrite process are applied to study how to recycle and stabilize copper sludge of PCB industry. The ultimate goal is to achieve cleaning production and sustainable development by transforming the hazardous waste into valuable byproducts, reducing the amount of the waste and lowering the treatment costs. Experimental results show that a method is successfully developed to recycle copper from the sludge generated by PCB industry by using the combination of acid leaching, chemical exchange and ferrite process. Via this method, not only is pure copper powder recycled, but highly valuable nano-scaled catalyst-CuFe2O4 is also produced. Hence, the problem that copper sludge has nowhere to go is solved, as well as the high cost of catalyst in catalytic incineration is reduced to nearly zero. The achievements of this study are summarized as follow: (1) Characteristic analysis of industrial sludge Water content and pH of the sludge is 60% and 7.05, respectively. The drop in quantity of ignition is 23%. The screening test results show that particle size of the sludge varies from 0.4 £gm to 200 £gm, with D50 of 25.0 £gm. Cu, Pb, Cd, Zn, Ni and Cr are found in the sludge, and the biggest part of heavy metals is Cu, with a concentration of 158,000 mg/kg (dry basis), whereas the other heavy metals are all below 105 mg/kg (dry basis). (2) Study of recycling of pure copper powder The optimal operational condition of acid leaching method is that concentration of sulfuric acid is 2.0 N, temperature is 50¢J and treatment time is 60 minutes. Under this operational condition, more than 99% of heavy metals can be extracted to liquid phase and the sediment of treated sludge meet Toxicity Characteristic Leaching Procedure (TCLP) standards and therefore is considered as general industrial waste. The optimal operational condition of chemical exchange method is that molar ratio of Fe/Cu is 5.0, pH is 2.0 and treatment temperature is 50¢J. Under this operational condition, more than 95.0% of Cu can be recovered. The optimal operational condition of ferrite process is that Fe/Cu=10.0, pH=9.0, treatment temperature=80¢J, aeration rate=3 L/min/per liter waste liquid and reaction time = 30 min. Under this operational condition, TCLP concentrations of all heavy metals of both supernatant and sludge are well below regulatory standards, which proves that ferrite process is very effective. (3) Resourcing of spinel sludge In the potential of catalytic incineration of volatile organic compounds test, the sludge generated from ferrite process is used to catalyze the isopropyl alcohol (IPA). The catalyst is replaced by the same volume of glass wool on a reactive bed as a blank. Experimental result shows that the conversion of IPA is only 10% at 200¢J and 75% at 500¢J in the absence of catalyst under the conditions that IPA inlet concentration=1,700 ppm, space velocity=24,000 hr-1, O2 concentration=21%, and relative humidity=19%, which indicates that the destruction of IPA is associated with the consumption of much energy when no catalyst was used. But when ferrite catalyst is applied, IPA is decomposed completely at 200¢J, showing that the sludge has great potential of catalyst. (4) Synthesizing five VOCs catalyzing ferrite catalysts via ferrite process As to the synthesis of five ferrite catalysts in the laboratory, IPA conversion rate is higher than 58% at 200¢J. The sequence of IPA conversion from good to bad is Cu-ferrite catalyst > Mn-ferrite catalyst > Ni-ferrite catalyst > Zn-ferrite catalyst > Cr-ferrite catalyst, where Cu/Fe is most efficiency, with IPA conversion rate of 75% at 150¢J and 100% at 200¢J.