<p>Quasicrystals is a new kind of material that have several interesting aspects to it. The unusual atomic structure entails many anomalous and unique physical properties, for example, high hardness, and extremely low electrical and thermal conductivity. In thin films quasicrystals would enable new functional materials with a combination of attractive properties.In this work, AlCuFe and Nanoflex steel, materials that are known to form quasicrystals in bulk, have been deposited as thin films on Si and Al2O3 substrates using DC magnetron sputtering. These thin films were heat treated, and the formation and growth of different phases, among other approximant and quasicrystalline phases, were studied using mainly in-situ X-ray diffraction.During the project several problems with the formation of quasicrystals were encountered, and it is proposed how to overcome these problems, or even how to make use of them. Finally, the quasicrystalline phase was realized, although it was not completely pure. In the end some suggestions for future work is presented.</p>

No description available.

The focus of this study was analytical investigations of Egyptian paintings, mainly Coptic icons and Islamic wooden ceilings, dating from 1300-1900 using multi-instrumental techniques. Twenty three Coptic icons and three wooden ceilings dated from different periods and painted by different painters in case of icons were examined. The materials used including pigments, media, varnishes, ground layers and gold layers. The surface stratigraphy of paint samples, their layered structured and the composition of materials used in each layer were analysed. Variations in painting techniques, pigments palettes, paint media and varnishes applied in Egyptian paintings according to painters, time and type of paintings were revealed. A total of twenty-eight organic and inorganic pigments were identified in this study, of which nine have never been previously included as a part of the Egyptian pigment palettes, namely; smalt, lapis lazuli, indigo, pararealgar, Prussian blue, chrome yellow, barium yellow, barium white and hydromagnesite. The identification of hydromagnesite, which has never been to date considered as a pigment either in Egypt or elsewhere and the identification of smalt from the mid-14th century, whose reported earliest large scale use was in the 16th century. Two types of resins were identified as a constituent of the oil/resin varnish applied on Coptic icons of which Venice turpentine has been identified for the first time as an ingredient of Egyptian varnishes. The identification of mosaic gold in an 18th C. icon, a novel usage of dammar resin and the multilayered structure of the white ground layers were revealed.

No description available.

In this thesis complexes of acylchalcogoureas with cadmium (II), lead (II) and nickel (II) have been synthesised and investigated as single source precursors for the formation of metal chalcogenide thin films viaaerosol assisted chemical vapour deposition (AACVD). Routes to binary thin films have been explored using homoleptic complexes of the general structure bis(N,N-diethyl-N'-naphthoylchalcogoureato)metal(II). Analysis of the thin films produced showed the successful deposition of the binary materials from the synthesised complexes when characterised by powder XRD, ICP-OES, SEM and EDX. Routes to ternary thin films with the general structure MExE'1-x, where M represents a metal (Cd, Ni and Pb); and E chalcogen (S or Se) have been investigated using heteroleptic metal complexes of cadmium, nickel or lead including different chalcogen containing N,N-diethyl-N'-naphthoylchalcogoureato ligands and diethyldithiocarbamate. The precursors were fully characterised and novel compounds had their crystal structures determined. The heteroleptic complexes were thermolysed by AACVD forming the MExE'1-x thin films. In the cases of lead, nickel and cadmium the thin films produced showed that the composition of the film tended heavily towards the metal selenide. Ternary films of type MS1-xSex was prepared by mixing their binary precursors of type bis(N,N-diethyl-N'-naphthoylselenoureato)metal(II) and bis(N,N-diethyl-N'-naphthoylthioureato)metal(II) [metal = Cd, Ni and Pb]. In the case of lead and cadmium chalcogenide films variation of the ratio of sulphur and selenium containing precursors allowed for the full transition in composition between metal sulphide and metal selenide. In the case of CdS1-xSexthe band gap of the films was determined from UV-visible spectroscopy to vary from 2.4 eV (CdS) to 1.7 eV(CdSe). In the case of NiS1-xSex the movement from sulphide to selenide was less simple with multiple phases of nickel chalcogenides produced.

Cette étude a pour objet d'apporter des éléments de compréhension quant à l'amélioration de la résistance à la corrosion des alliages de ZnMg(Al), en comparaison du Zn, en milieu atmosphérique chloré. Le cheminement de réflexion part de considérations fondamentales et tend vers des conditions réelles d'utilisation. La première étape a consisté à synthétiser et caractériser des films de ZnO dopé Mg et notamment l'évolution de la structure cristalline, la structure électronique, la résistivité, (...) avec le dopage. La pertinence de ces paramètres a ensuite été évaluée et discutée au regard de la stabilité de ces films en solution. Dans un second temps, les produits de corrosion formés, en laboratoire, en présence ou non de chlorures, sur des phases pures de Zn et ZnMg, ont été caractérisés. Les processus physico-chimiques liés à la formation de ces produits ont ensuite été discutés, afin de mettre en lumière le rôle du Mg dans l'amélioration de la résistance à la corrosion. La dernière étape, s'est attachée à caractériser des produits de corrosion formés après 6 mois en milieu naturel, en atmosphère marine, sur des phases pures de Zn et ZnMg, et des revêtements industriel de type ZnMgAl. Les résultats obtenus ont permis de mettre en évidence une meilleure stabilité en solution des films de Zn0.84Mg0.16O en comparaison du ZnO, en corrélation avec une présence accrue de liaisons hydroxyles, une augmentation de la résistivité et de la fonction de travail. Ces trois paramètres sont apparus également pertinents, sur les produits de corrosion formés en laboratoire et naturellement en présence de Mg et de Mg, Al, et corrélés à l'amélioration de la résistance à la corrosion.

The thermal formation of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), biphenyls (PCBs), and naphthalenes (PCNs) is a major problem in waste incineration. Ideally, rather than relying on air cleaning systems and treatment techniques, their formation should be minimized or, if possible eliminated. The work presented in this thesis was conducted to obtain a deeper understanding of the thermal formation of PCDDs, PCDFs, PCBs, and PCNs during incineration using a 5 kW laboratory scale incinerator and two artificial wastes that were designed to reflect regional differences in waste composition. The first part of the thesis focuses on the validation of a recently-developed flue-gas sampling probe with enhanced cooling capabilities. Artifact formation of PCDDs and PCDFs can occur during the sampling of hot flue gases if the cooling is insufficient. The new probe was successfully used to collect samples at 700 °C without biasing the measured POP levels. The thermal formation of PCDDs, PCDFs, PCBs, and PCNs in the post-combustion zone of the incinerator was then studied by collecting flue gas samples at 400 °C, 300 °C, and 200 °C during the incineration of the two artificial wastes. Highly chlorinated POPs were formed in larger quantities when burning the waste with the higher content of metals and chlorine, which suggests that high metal levels in the waste favor the chlorination of less chlorinated POPs or otherwise facilitate the formation of highly chlorinated polyaromatics, possibly via the condensation of highly chlorinated phenols. The concentrations of these pollutants and the abundance of highly chlorinated homologues increased as the flue gas cooled. Fly ash particles play an important role in thermal POP formation by providing essential elements (carbon, chlorine, etc.) and catalytic sites. The chemical and mineralogical properties of fly ash samples were studied by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), Scanning Electron Microscopy/Energy Dispersive X-ray (SEM/EDX), and X-ray photoelectron spectroscopy (XPS) to determine their impact on thermal POP formation. Orthogonal Partial Least Squares (OPLS) modeling was used to identify correlations between the observed POP distributions and the physicochemical data. This investigation provided new insights into the impact of fly ash chemistry on thermal POP formation. In addition, the POP isomer distribution patterns generated during waste combustion were examined. These patterns are used to “fingerprint” mechanisms of POP formation. It was found that wastes containing large quantities of metals and chlorine favored the formation of highly chlorinated homologues including the very toxic 2,3,7,8-congeners. The data suggest that reducing fly ash emissions might increase the SO2 content of the flue gas and thereby suppress the Deacon process and the formation of harmful highly chlorinated aromatic species.

Sulfate-reducing bacteria (SRB) frequently occur in the deep granitic rock aquifers at the Äspö Hard Rock Laboratory (Äspö HRL), Sweden. The new SRB strain Desulfovibrio äspöensis could be iso-lated. The objective of this project was to explore the basic interaction mechanisms of uranium, curium, neptunium and plutonium with cells of D. äspöensis DSM 10631T. The cells of D. äspöensis were successfully cultivated under anaerobic conditions as well in an optimized bicarbonate-buffered mineral medium as on solid medium at 22 °C. To study the interaction of D. äspöensis with the actinides, the cells were grown to the mid-exponential phase (four days). The collected biomass was usually 1.0±0.2 gdry weight/L. The purity of the used bacterial cultures was verified using microscopic techniques and by applying the Amplified Ribosomal DNA Restriction Enzyme Analysis (ARDREA). The interaction experiments with the actinides showed that the cells are able to remove all four actinides from the surrounding solution. The amount of removed actinide and the interaction mechanism varied among the different actinides. The main U(VI) removal occurred after the first 24 h. The contact time, pH and [U(VI)]initial influence the U removal efficiency. The presence of uranium caused a damaging of the cell membranes. TEM revealed an accumulation of U inside the bacterial cell. D. äspöensis are able to form U(IV). A complex interaction mechanism takes place consisting of biosorption, bioreduction and bioaccumulation. Neptunium interacts in a similar way. The experimental findings are indicating a stronger interaction with uranium compared to neptunium. The results obtained with 242Pu indicate the ability of the cells of D. äspöensis to accumulate and to reduce Pu(VI) from a solution containing Pu(VI) and Pu(IV)-polymers. In the case of curium at a much lower metal concentration of 3x10-7 M, a pure biosorption of Cm(III) on the cell envelope forming an inner-sphere surface complex most likely with organic phosphate groups was detected. To summarize, the strength of the interaction of D. äspöensis with the selected actinides at pH 5 and actinide concentrations ≥10 mg/L ([Cm] 0.07 mg/L) follows the pattern: Cm > U > Pu >> Np.

Grâce à ses propriétés d'antioxydant, d'anti-usure et éventuellement d'extrême pression le dithiophosphate de zinc (ZDDP) fait partie des additifs les plus utilisés dans les lubrifiants pour moteurs thermiques. De nos jours, dans un souci de respect de l'environnement, de nouveaux lubrifiants possédant de bonnes performances en lubrification (frottement faible et usure limitée) sont développés en prenant compte des limitations d'utilisations actuelles du ZDDP. L'idée étant de réduire dans ceux-ci les teneurs en phosphore et soufre (Normes euros VI), éléments essentiels du ZDDP qui endommagent les pots catalytiques. L'objectif de cette thèse est l'étude du comportement tribologique du phosphate de zinc di alkyl (ZP) en comparaison avec le ZDDP. La méthodologie expérimentale étudiée pour comprendre le mécanisme d'action de ces additifs, associe des essais de frottement à descaractérisations physico-chimiques des surfaces frottantes après essais.Cette comparaison a été effectuée en fonction de la température (25°C et 100°C), la vitesse de glissement (25, 50 et 100 mm/s) et la concentration en additif (200 et 600 ppm dephosphore). Les meilleures actions anti-usure sont obtenues avec le ZDDP pour une température de 100°C et une vitesse de glissement de 100 mm/s et le ZP pour une température de 25°C et une vitesse de glissement de 25 mm/s. Les analyses de surface XPS, AES, XANES et MET-EDX ont permis de mettre en évidence la présence d'un film protecteur constitué principalement de phosphate de zinc, ceci pour les deux additifs.Une synergie de comportement tribologique a été mise en évidence avec un lubrifiantconstitué de ZP (usure faible) et d'oléate d'urée (frottement faible). Des essais complémentaires sur un tribomètre dynamique ont permis d'étudier le niveau de frottement du tribofilm formé à partir du ZDDP. Le caractère visqueux du tribofilm de ZDDP a été mis en évidence.

No description available.