[pt] O aumento da concentração de dióxido de carbono na atmosfera vem sendo apontado como um possível causador das mudanças climáticas, o que tem incentivado o crescimento do número de estudos sobre formas de redução dos níveis deste gás na atmosfera. O objetivo deste trabalho é desenvolver materiais nanoestruturados que possam ser utilizados como adsorventes de CO2 em condições brandas de operação. A partir da avaliação de alguns processos pré-selecionados, foram sintetizados e caracterizados materiais que têm afinidade com este gás, apresentando alta área superficial e sítios básicos. Assim, foram produzidos óxidos de cálcio e magnésio, utilizando nitratos como precursores em uma técnica de precipitação em solução aquosa e calcinação. Estes óxidos foram analisados com o auxílio das técnicas de DRX e MEV/EDS, definindo a composição química elementar e a morfologia das superfícies. As áreas superficiais foram definidas por meio do método de BET, sendo 34 m2/g para o MgO, 19 m2/g para o CaO e 26 m2/g para a mistura MgO/CaO, e estimados os diâmetros de partícula, caracterizando-se os materiais como nanométricos. Os valores foram 49 nm para o MgO, 94 nm para o CaO e 67 nm para a mistura MgO/CaO. Finalmente, foram feitos testes de TPD, avaliando-se a capacidade de adsorção dos materiais sintetizados em condições prédeterminadas e a viabilidade de uso na adsorção do dióxido de carbono. Os resultados obtidos foram 103 micromol/g para o MgO, 126 micromol/g para o CaO e 319 micromol/g para a mistura MgO/CaO, sendo possível concluir que o processo proposto é viável tecnicamente, comparando-se esses resultados obtidos com os encontrados nos trabalhos previamente analisados. / [en] The increasing concentration of carbon dioxide in the atmosphere has been pointed out as one possible causer of climate changes, what has been encouraging the rising number of studies about means to reduce the level of this gas in the atmosphere. The purpose of this work is to develop nanosized materials that can be used as CO2 sorbents in mild operational conditions. Starting with the assessment of some preselected capture processes, materials that have affinity with this gas were synthesized and characterized, presenting high surface area and basic sites. Thus, calcium and magnesium oxides were produced using nitrates as precursors in a technique of precipitation in aqueous solution and calcination. These oxides were analyzed using DRX and MEV/EDS techniques, defining the elementary chemical composition and the morphology of their surfaces. Surface areas were defined by BET method, as 34 m2/g for MgO, 19 m2/g for CaO and 26 m2/g for the mixed oxides MgO/CaO, and the particle diameters were estimated, characterizing them as nanosized materials. Finally, TPD tests were made, evaluating the sorption capacity of the synthesized materials in preselected conditions and their viability in the adsorption of carbon dioxide. The results obtained were 103 micromol/g for MgO, 126 micromol/g for CaO and 319 micromol/g for the mixed oxides MgO/CaO, being possible to conclude that the proposed process is technically viable, comparing these results with the ones found in the previously analyzed works.

A versatilidade das espumas poliuretanas permite sua aplicação em inúmeros setores industriais, devido à possibilidade de se obter diferentes conjuntos de propriedades apenas alterando sua formulação básica. Um tipo recorrente de alteração é a incorporação de diferentes tipos de fibras em matrizes de poliuretano, vastamente estudada com o objetivo de gerar materiais compósitos com melhores propriedades mecânicas do que a matriz original. Inúmeros autores reportaram a utilização de celulose cristalina como uma alternativa renovável aos agentes de reforço e revelaram que a celulose utilizada como aditivo em matrizes poliméricas afetou as propriedades mecânicas da matriz original e, em menor escala, exerceu influência sobre a estabilidade térmica do compósito. O presente trabalho dedicou-se a isolar a celulose cristalina contida nas fibras de bananeira mediante tratamento com ácido acético concentrado. Os tratamentos químicos são necessários para modificar a superfície do material e melhorar a adesão do agente de reforço à matriz. Tendo em vista os resultados associados à estabilidade térmica dos compósitos de poliuretano reforçados com celulose, buscou-se sintetizar materiais híbridos de celulose e MgO.nH2O. Foi observado que, mesmo em pequenas quantidades, a presença do óxido hidratado de magnésio afetou significativamente a estabilidade térmica do HB 98:2. Estudos térmicos indicam que os materiais compósitos estudados apresentaram comportamento semelhante ao da matriz PU. Estudos das propriedades compressivas dos materiais poliméricos gerados mostraram que a incorporação do HB 98:2 ao PU afetou positivamente as propriedades mecânicas do material, sendo que o compósito PU + 1 HB 98:2 apresentou desempenho mecânico superior ao da matriz pura. / The versatility of polyurethanes foams allows its application in numerous industries because of the possibility of obtaining different sets of properties just by changing its basic formulation. A recurrent type of modification is the incorporation of different types of fibers in polyurethane matrices widely studied with the objective of generating composite materials with better mechanical properties than the original matrix. Numerous authors have reported the use of crystalline cellulose as a renewable alternative to fillers and showed that the cellulose used as additive in polymer matrices affect the mechanical properties of the original matrix and, to a lesser extent, influence upon thermal stability of the composite. This work was dedicated to isolate the crystalline cellulose contained in banana fibers by treatment with concentrated acetic acid. The chemical treatments are needed to modify the surface of the material and improve adhesion of the filler to the matrix. In view of the results associated with the thermal stability of the composite polyurethane reinforced with cellulose, sought to synthesize hybrid materials cellulose and MgO.nH2O. It has been observed that even in small quantities, the presence of hydrated magnesium oxide significantly affect the thermal stability of HB 98: 2. thermal studies indicate that the studied composites showed similar behavior to the PU matrix. Studies of the compressive properties of polymeric materials generated showed that the incorporation of HB 98: 2 to PU positively affect the mechanical properties of the material, and the composite PU + HB 98 1: 2 had mechanical performance superior to that of pure matrix.

Les ciments phosphomagnésiens sont des ciments inorganiques de la famille des ciments activés par des acides. Malgré le fait qu'ils soient connus depuis le début du XXème siècle, leur utilisation reste assez limitée dans le génie civil. Ces matériaux sont utilisés dans le cadre de réparation notamment pour des réparations routières qui nécessitent un développement rapide des résistances en compression. Plus récemment, ces ciments ont été utilisés pour des applications de stabilisation/solidification (S/S) des déchets et notamment de certains types de déchets chimiquement incompatibles avec le ciment Portland. Toutefois, les défis de mise en œuvre de ce type de ciment sont liés à la nature même de la réaction, très exothermique et très rapide. La phase liante de ces ciments, la k-struvite (MgKPO4.6H2O), est obtenue par un mélange de magnésie (MgO) et de dihydrophosphate de potassium (KH2PO4) en présence d'eau. MgO + KH2PO4 + 5H2O  MgKPO4.6H2OLes mécanismes qui régissent la prise de ce ciment sont encore mal connus et plusieurs théories, mettant en jeu ou non la formation de produits secondaires, ont été proposées. Nos travaux de recherche ont porté sur la compréhension des mécanismes de prise des ciments phosphomagnésiens ainsi que sur l'influence des paramètres de formulation sur les propriétés de ces ciments. L'étude a montré que la formation de la k-struvite passe par une réaction de précipitation-dissolution d'un produit intermédiaire, la newberyite (MgHPO4.3H2O). Les réactions de formation de ces deux produits sont contrôlées par le taux de sursaturation des espèces en solution et le pH du milieu réactionnel. L'étude met également en lumière la forte sensibilité de ces ciments à la quantité d'eau introduite. Avec un rapport E/C très faible comparativement à un ciment Portland (rapport E/C compris entre 0,1 et 0,25), une faible variation (0,02) entraine la ségrégation de la pâte de ciment et une hétérogénéité à la surface du matériau. Parmi les paramètres de formulation, le rapport molaire MgO/KH2PO4 (Mg/P) est le plus important. En effet, il influe sur la quasi-totalité des propriétés du ciment : résistance en compression, temps de prise, chaleur de réaction, fluidité de la pâte, …. L'utilisation de faibles rapports Mg/P entraine une mauvaise tenue à l'eau du ciment, la formation de cristaux à l'intérieur de la microstructure et visibles à la surface de l'échantillon (apparition d'une efflorescence) ainsi qu'un gonflement important de la pâte de ciment (pouvant aller jusqu'à la fissuration des échantillons). A l'issue de l'étude paramétrique une formulation d'une pâte a pu être définie. Des mesures de variations dimensionnelles, ainsi que des mesures de retrait chimique ont été effectuées, afin de mieux comprendre les mécanismes mis en jeu pour induire les phénomènes de gonflement. En support, des analyses de la microstructure (MEB, DRX, ATG) ainsi que des essais de lixiviation viennent compléter la campagne expérimentale. Ces résultats viennent confirmer l'influence d'un rapport Mg/P faible sur le gonflement et la tenue à l'eau du ciment phosphomagnésien. Pour finir, une étude sur l'influence des divers ajouts, dans le but d'améliorer ses performances, a montré que les fillers inertes (sable siliceux ou cendres volantes) retardent le temps de prise et réduisent la chaleur d'hydratation / Magnesium phosphate cements are the most representative cements of the activated-by-acid cements family. Despite the fact that they are known since the early 20th century, their use in civil engineering is fairly limited. These materials are used for road repairs where the fast compressive strength development is an advantage. Recently they have also been used in wastes stabilization/solidification (S/S), especially with wastes incompatible with Portland cement. The challenges of the use of these cements are related to the nature of their formation reaction: fast, very exothermic, with a very short setting time (only a few minutes).The bonding phase, k-struvite (MgKPO4.6H2O), is obtained from magnesium oxide mixed in water with monopotassium phosphate (KH2PO4).MgO + KH2PO4 + 5H2O  MgKPO4.6H2OThe setting mechanisms are still poorly known and various theories, involving or not secondary product formation, have been suggested. Our researches have aimed to understand the setting mechanisms, as well as the influence of the formulation parameters on the properties of the magnesium phosphate cement. Results show that the formation of k-struvite involved a precipitation-dissolution reaction of an intermediate product, the newberyite (MgHPO4.3H2O). Formation reactions of these two products are controlled by the supersaturation rate and the pH of the solution. The study highlights the strong effect of water on the properties of fresh cement paste. With a low mass ratio e/c in comparison of Portland cement (ratio e/c between 0,1 and 0,25), a slight modification of the ratio (0,02) leads to a segregation and a surface heterogeneity of the cement paste. Among the formulation parameters, the molar ratio MgO/KH2PO4 (Mg/P) seems the most important parameter. Indeed, it impacts most of the properties of the magnesium phosphate cement (compressive strength, setting time, reaction heat, paste fluidity …). Low Mg/P ratios lead to poor water resistance, to crystals formation inside the microstructure that can be seen on the surface of the sample (an efflorescence appearance), and to important swelling of the paste, leading to the cracking of the samples. After the parametric study, a magnesium phosphate cement paste has been defined. Dimensional changes and chemical shrinkage measurement were conducted to understand the mechanisms involved in this swelling phenomenon. In support, microstructural analyses (SEM, XRD, TGA) and leaching tests complete the experimental campaign. The results confirm the influence of a low Mg/P ratio on cement swelling and water resistance. Finally, a study on various additions to the paste has been conducted, with the purpose of improving the cement paste performances. It shows that the addition of an inert filler (siliceous sand or fly ashes) has a retarding effect and reduced the reaction heat

No description available.

In the copper smelting processes, the viscosity of the matte and the slag is an important factor for establishing efficiency. Impurities in the concentrates affect the viscosity not only by changing the melt structure but also by promoting precipitation of solid phase which sharply rises it. In this master thesis, a comprehensive methodology was established to study the MgO effects on the properties of a copper smelting slag. Thus, glassy samples were obtained and after confirmation of the composition and the glassy structure with EDS, SEM, and XRD analysis, they were examined through Ramanspectroscopy to study their glassy structure. Moreover, Mössbauer spectroscopy was used to determine the amount of Fe3+ in the samples. Models from the literature were compared to the experimental data. Coherence with the literature was found with the effect of MgO as a network modifier of the oxide melt structure and a promoter of high coordinated structures. Estimations through models were performed to study the iron redox equilibria of the melt and were compared with experimental data, but it was not possible to find the limit of Fe3+ at which precipitation of solid phase initiates. / I kopparsmältningsprocesserna är mattans och slaggens viskositet en viktig faktor för att uppnå effektivitet. Föroreningar i koncentraten påverkar viskositeten inte bara genom att ändra smältstrukturen utan också genom att främja utfällning av fast fas som kraftigt höjer den. I denna magisteruppsats fastställdes en omfattande metod för att studera MgO-effekterna på egenskaperna hos en kopparsmältningsslagg. Således erhölls glasiga prover och efter bekräftelse av kompositionen och den glasiga strukturen med EDS-, SEM- och XRD-analys undersöktes de genom Ramanspektroskopi för att studera deras glasstruktur. Dessutom användes Mössbauerspektroskopi för att bestämma mängden Fe3+ i proverna. Modeller från litteraturen jämfördes med experimentella data. Överensstämmelse med litteraturen hittades med effekten av MgO som ett nätverksmodifierare av oxidsmältstrukturen och en promotor för högkoordinerade strukturer. Uppskattningar genom modeller utfördes för att studera smältans järnredoxjämvikter och dessa jämfördes med experimentella data, men det var inte möjligt att hitta gränsen för Fe3+ vid vilken utfällning av fast fas initierades.

Die vorliegende Dissertation präsentiert eine detaillierte quantenchemische Untersuchung der H-Abstraktion von Methan durch MgO und Li dotiertes MgO. Motiviert wurde die durch das UniCat-Excellenz-Cluster, welches sich zum Ziel gesetzt hat, die oxidative Kupplung von Methan (OCM) im Detail zu verstehen. Basierend auf der Hypothese, dass Li+O•– Spezies für den H-Abstraktion Schritt verantwortlich sind, wurden kleine kationische MgO- und Li dotierte MgO-Cluster (die O•– Sites modellieren) untersucht. Zur Erstellung von möglichst realen Gasphasen-Modell-Systemen, wurde die globalen Minima der Gasphasencluster mittels eines genetischen Algorithmus bestimmt. Zum Vergleich wurden auch die Strukturen von neutralen MgO-Cluster bestimmt, um eventuelle strukturelle Unterschiede zu erkennen. Anschließend wurden die optimierten Cluster in Bezug auf ihre Eignung zur C-H-Bindungsaktivierung von Methan untersucht. Die Verwendung von kleinen Cluster-Größen ermöglicht es, die Reaktion im Detail zu studieren und verschiedene Methoden der Berechnung zu vergleichen. Die Ergebnisse für die kleinen Cluster wurden anschließend mit realistischeren Modellen verglichen, die eine genauere Beschreibung der Li dotierten Oberflächen ermöglichen, wie zum Beispiel non-embedded und embedded-Cluster und slab Modelle. Unerwartete Ergebnisse für die Betrachtung der Li+O•– Spezies haben zur Untersuchung von zusätzliche Arten von Defekten in MgO (wie niedrig koordinierten O2-Seiten, O-Leerstellen mit unterschiedlicher Ladung und Verunreinigungen) geführt, die als aktive Zentren in OCM fungieren können. Insbesondere wurden morphologische Defekte und verschiedene Arten von F Zentren untersucht. Die Aktivierung von Methan an defekten MgO-Oberflächen wurde innerhalb eines Cluster-Ansatzes untersucht und durch periodische Berechnungen mittels periodic slab models verifiziert. Die Ergebnisse wurden mit vorhandenen experimentellen Daten verglichen. / This work presents a detailed quantum chemical (mostly DFT) study of H abstraction from methane by MgO and Li doped MgO. It is motivated by the UniCat effort to understand the oxidative coupling of methane (OCM). Based on the hypothesis that an Li+O•– species is responsible for the H abstraction step in OCM small cationic MgO and Li doped MgO clusters (which model O•– sites) were investigated. Because we were interested in real gas phase model systems the global minimum structures of (MgO)n+ and LiO(MgO)n-1 clusters were first determined (by means of genetic algorithm) and then used in subsequent reactivity studies. To check if there are any structural differences between neutral and cationic MgO clusters the neutral species were studied as well. After structure determination, the activation of methane by the O•– radical sites was investigated. The small cluster sizes enabled to study the reaction in detail and to compare different methods of calculations. The results were verified by comparison with more realistic models that mimic Li doped MgO surface, like non-embedded and embedded clusters and slab models. However, unexpected results for the Li+O•– sites led to the consideration of additional types of sites in MgO that may be active for OCM – such as low-coordinated O2- sites, O vacancies with different charge and impurity defects. In particular morphological defects and different types of F centers were investigated. Methane activation by defective MgO surface was studied by a cluster approach and then followed by periodic calculations on periodic slab models. The results were compared to existing experimental data.

Die Erzeugung spinpolarisierter Ladungsträger in einem Halbleiter gilt als Grundvoraussetzung zur Realisierung spintronischer Bauelemente. Einen möglichen Ansatz zu deren Realisierung stellen Ferromagnet/Halbleiter(FM/HL)-Hybridstrukturen dar, deren Herstellung jedoch mit einigen Schwierigkeiten verbunden ist. Durch die Vermischung des ferromagnetischen Materials mit dem Halbleiter werden die elektronischen Eigenschaften der Hybridstruktur verändert und die Spininjektionseffizienz stark verringert. Durch das gezielte Einfügen einer dünnen Oxidschicht in den FM/HL-Grenzübergang kann die Diffusion unterdrückt, die Kristallqualität verbessert und die Effizienz der Struktur erhöht werden. Diese Arbeit beschäftigt sich mit dem Wachstum und der Charakterisierung dünner Oxidschichten, hergestellt mittels Molekularstrahlepitaxie. Zwei Seltenerdoxide, La2O3 und Lu2O3, werden auf GaAs-Substraten gewachsen und die Kristallqualität der Schichten miteinander verglichen. Mit der Heusler-Legierung Co2FeSi als Injektorschicht wird eine FM/Oxid/HL-Hybridstruktur auf Basis einer La2O3/GaAs(111)B-Struktur realisiert und magnetisch und elektrisch charakterisiert. Ein häufig verwendetes Barrierenmaterial in FM/HL-Hybridstrukturen ist Magnesiumoxid (MgO). In dieser Arbeit werden dünne MgO-Schichten auf GaAs(001) an der PHARAO-Wachstumsanlage am BESSY II erzeugt. Dies geschieht durch getrenntes Verdampfen von metallischem Mg bzw. Einleiten von molekularem Sauerstoff in die Wachstumskammer. Um die Oxidation des Halbleitersubstrats zu verhindern, wird vor dem MgO-Wachstum eine dünne Mg-Schicht abgeschieden. Abhängig von der Dicke dieser Schicht sind zwei in-plane-Orientierungen des MgO relativ zum GaAs kontrolliert einstellbar. Darüber hinaus werden Hybridstrukturen mit Eisen Fe als Injektorschicht und schrittweise erhöhter MgO-Schichtdicke gewachsen. Die Eindiffusion von Fe in das GaAs-Substrat nimmt mit zunehmender MgO-Schichtdicke um mehrere Größenordnungen ab. / The generation of spin-polarized charge carriers in a semiconductor is a basic building block for the implemention of spintronic devices. A feasible approach to their implementation are ferromagnet/semiconductur(FM/SC) hybrid structures, whose fabrication is associated with some issues. The intermixing of the ferromagnetic material with the semiconductor leads to distortion of the electrical properties of the hybrid structure and the spin injection efficiency is reduced. By intentionally inserting a thin oxide layer into the FM/SC interface diffusion can be suppressed while the crystal quality and the spin injection efficiency of the structure are both increased. In this thesis the growth and characterization of thin oxide films fabricated by molecular beam epitaxy are discussed. Two rare earth oxides, La2O3 and Lu2O3, are grown on GaAs substrates and their crystal qualities are compared. Based on La2O3/GaAs(111)B full FM/SC hybrid structures are grown with the Heusler alloy Co2FeSi as injection layer and characterized by magnetic and electrical means. Another material used as a barrier in FM/SC hybrid structures is magnesium oxide (MgO). Here, thin MgO layers are grown on GaAs(001) at the PHARAO system at BESSY II. The growth is conducted by the separated evaporation of metallic Mg and introducing molecular oxygen into the growth chamber. To avoid oxidation of the semiconducting substrate a thin Mg layer is deposited prior to the MgO growth. Depending on the Mg layer thickness two different MgO in-plane orientations can be achieved with respect to the GaAs substrate. Furthermore, FM/SC hybrid structures with iron Fe as injection layer are grown while the MgO layer thickness is increased gradually. The indiffusion of Fe into the GaAs substrate is suppressed by several orders of magnitude with increasing MgO layer thickness.

Dans cette étude, nous proposons d’utiliser la compression in situ dans le MET afin de caractériser les propriétés mécaniques de nanoparticules céramiques dont la taille caractéristique est de l’ordre de quelques dizaines de nanomètres. Nous appliquerons cette méthode à des nanocubes monocristallins de MgO, une céramique modèle dont la plasticité est bien connue dans le matériau massif. Les essais de nanocompression montrent que les nanocubes de MgO se déforment de façon homogène jusqu’à de grandes déformations (>50%) sans fissure apparente. L’analyse des résultats est assistée par des méthodes de corrélation d’images numériques et simulations de type dynamique moléculaire. Le mécanisme de déformation et l'effet de taille sur la limite élastique sont identifiés. Dans une deuxième partie de la thèse, nous présentons une étude sur des nanoparticules d’alumine de transition compactée en CED (Cellule à Enclumes en Diamant) à température ambiante, sous plusieurs pressions (5 GPa, 15 GPa et 20 GPa). Des lames minces préparées par FIB ont été étudiées en MET. Des images HRTEM montrent une texture cristallographique qui devient plus importante à des pressions plus élevées. Une orientation cristallographique préférentielle est observée, avec les plans {220} de la phase gamma de l’alumine la plupart du temps parallèles à la surface de contact avec une particule voisine. Ce comportement mécanique est cohérent avec un système de glissement, connu pour les structures spinelles. Une corrélation de ce comportement avec les tests in situ MET réalisés sur des nanoparticules similaires, par Emilie Calvié lors de sa thèse, est présentée. Enfin, des clichés de diffraction de type Debye Scherrer sont réalisés sur ces lames minces de nanoparticules d’alumine de transition compactées en CED à différentes pressions. L’analyse quantitative de ces clichés montre une transformation de phase de ces nanoparticules d’alumine de phase gamma en phase delta, de manière croissante avec la pression. / In this study, we propose an innovative mechanical observation protocol of ceramics nanoparticles in the 100nm size range. This Protocol consists of in situ TEM nanocompression tests of isolated nanoparticles. Load–real displacements curves, obtained by Digital Image Correlation, are analyzed and these analyses are correlated with Molecular Dynamics simulations. By this protocol a constitutive law with its mechanical parameters (Young modulus, Yield stress...) of the studied material at the nano-scale can be obtained. In situ TEM nano-compression tests on magnesium oxide nanocubes are performed. Magnesium oxide is a model material and its plasticity is very well known at bulk. The MgO nanocubes show large plastic deformation, more than 50% of plastic strain without any fracture. The TEM results are correlated to MD simulations and the deformation mechanism can be identified.The size effect and the electron beam effect on the yield strength are investigated. In a second part of the dissertation, we present a study on transition alumina nanoparticles compacted in a Diamond Anvil Cell at different uniaxial pressures. Thin Foils of these compacted nanoparticles are prepared by FIB for HRTEM Observations. Their analysis reveals the plastic deformation of the nanoparticles. The crystallographic texture observed inthese compacted nanoparticles in DAC shows a preferred orientation of the {110} lattice planes, orientated perpendicular to the compression direction. This is compatible with the slip system. This argument was reinforced with a preferred orientation of slip bands observed during in situ TEM nano-compression tests. Moreover, electron diffraction patterns (Debye Scherrer) analysis on these compacted transition alumina nanoparticles reveals the decrease of the presence of gamma-alumina and the increase of delta-alumina with increasing pressure. This reveals the phase transformation with increasing pressure from gamma to delta* alumina.

The synthesis and characterization of bis(ketoiminato)magnesium(II) complexes of composition [Mg(OCR2CH2CHR1NCH2CH2X)2] (X = NMe2: 3a, R1 = R2 = Me; 3b, R1 = Me, R2 = Ph. X = OMe: 3c, R1 = R2 = Me) are reported. Complexes 3a–c are accessible by the reaction of C(O)R2CH2CHR1N(H)CH2CH2X (X = NMe2: 1a, R1 = R2 = Me; 1b, R1 = Me, R2 = Ph. X = OMe: 1c, R1 = R2 = Me) with MgnBu2. The structure of 3b in the solid state was determined by a single crystal X-ray diffraction study, confirming that the Mg(II) ion is hexa-coordinated by two ketoiminato ligands, while each of the latter coordinates with its two N- and one O-donor atom in an octahedral MgN6O2 coordination environment in the OC-6-33 stereo-isomeric form. The thermal behavior of 3a–c was studied by TG and DSC under an atmosphere of Ar and O2 respectively. The respective Me-substituted complexes 3a,c decompose at lower temperatures (3a, 166 °C; 3c, 233 °C) than the phenyl derivative 3b (243 °C). PXRD studies indicate the formation of MgO. Additionally, TG-MS studies were exemplarily carried out for 3a, indicating the release of the ketoiminato ligands. Vapor pressure measurements were conducted at 80 °C, whereby 3a,c possess with 5.6 mbar (3a) and 2.0 mbar (3c) significantly higher volatilities than 3b (0.07 mbar). Complexes 3a–c were used as MOCVD precursors for the deposition of thin MgO films on silicon substrates. It was found that only with 3a,c thin, dense and rather granulated MgO layers of thicknesses between 28–147 nm were produced. The as-deposited MgO layers were characterized by SEM, EDX, and XPS measurements and the thicknesses of the as-deposited layers were measured by Ellipsometry and SEM cross-section images. Apart from magnesium and oxygen a carbon content between 3–4 mol% was determined.

The synthesis of complexes [M(OCHMeCH2NMeCH2)2] (5, M = Mg; 7, M = Zn) is described. Treatment of MeHNCH2CH2NMeH (1) with 2-methyloxirane (2) gave diol (HOCHMeCH2NMeCH2)2 (3), which upon reaction with equimolar amounts of MR2 (4, M = Mg, R = Bu; 6, M = Zn, R = Et) gave 5 and 7. The thermal behavior and vapor pressure of 5 and 7 were investigated to show whether they are suited as CVD (= chemical vapor deposition) and/or spin-coating precursors for MgO or ZnO layer formation. Thermogravimetric (TG) studies revealed that 5 and 7 decompose between 80–530 °C forming MgO and ZnO as evidenced by PXRD studies. In addition, TG-MS-coupled experiments were carried out with 7 proving that decomposition occurs by M–O, C–O, C–N and C–C bond cleavages, as evidenced from the detection of fragments such as CH4N+, C2H4N+, C2H5N+, CH2O+, C2H2O+ and C2H3O+. The vapor pressure of 7 was measured at 10.4 mbar at 160 °C, while 5 is non-volatile. The layers obtained by CVD are dense and conformal with a somewhat granulated surface morphology as evidenced by SEM studies. In addition, spin–coating experiments using 5 and 7 as precursors were applied. The corresponding MO layer thicknesses are between 7–140 nm (CVD) or 80 nm and 65 nm (5, 7; spin-coating). EDX and XPS measurements confirm the formation of MgO and ZnO films, however, containing 12–24 mol% (CVD) or 5–9 mol% (spin-coating) carbon. GIXRD studies verify the crystalline character of the deposited layers obtained by CVD and the spin-coating processes.