Дисертації з теми "Metal precursor"
Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Metal precursor.
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 дисертацій для дослідження на тему "Metal precursor".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
1
Dinnage, Christopher Walker. "Molecular precursor routes to transition metal sulfides." Thesis, University College London (University of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252054.
Повний текст джерела
2
Peters, Emily Sarah. "Precursor synthesis and chemical vapour deposition of transition metal sulfides." Thesis, University College London (University of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408505.
Повний текст джерела
3
Marnell, Lisa. "Adsorption of precursor molecular magnets on single crystal metal surfaces." Thesis, University of Liverpool, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.439490.
Повний текст джерела
4
Rehermann, Carolin. "Exploring the Precursor-Process-Property Space in Metal Halide Perovskite Thin-Films." Doctoral thesis, Humboldt-Universität zu Berlin, 2021. http://dx.doi.org/10.18452/23095.
Повний текст джерелаАнотація:
Die Anpassung der Bandlücke und die Herstellung mittels lösungsbasierter Prozesse charakterisieren Metallhalogenid-Perowskite. Sie sind vielversprechend für die Anwendung in optoelektronischen Bauteilen, die die Abscheidung von hochwertigen Dünnschichten erfordern. Deren Qualität hängt stark vom Kristallisationsverhalten ab, welches durch die Komposition der Lösung bestimmt ist. Ziel dieser Arbeit ist es, Korrelationen im Präkursor-Prozess-Eigenschaftsraum von Metallhalogenid-Perowskit zu bewerten und Formierungsprozesse zu rationalisieren.
Phasenreinheit, Morphologie und Absorptionseigenschaften zeichnen die Qualität der Perowskit-Dünnschichten aus. Die Optimierung der Herstellung von hochwertigen Filmen über einen breiten Bandlückenbereich wird zuerst beleuchtet. Die Rationalisierung der Formierungsprozesse erweist sich als fundamental, um reproduzierbare Präparationsroutinen für hochwertige Filme zu entwickeln.
Anschließend wird ein optischer in-situ Aufbau zur Rationalisierung von Formierungsprozessen vorgestellt. Abhängig vom Halogenidverhältnis in der MAPb(IxBr1-x)3-Reihe werden verschiedene Formierungswege eingeschlagen. Während sich das reine Bromid direkt und Iodid reiche Perowskite über die intermediäre Solvatphase (MA)2(DMSO)2Pb3I8 bilden, bilden sich gemischte Halogenide zwischen 0.1 ≤ x ≤ 0.6 über beide Wege. Die Formierung über konkurrierende Wege erklärt die kompositorische Heterogenität der gemischten Halogenidproben.
Zuletzt werden Formierungsprozesse von Bromid-Perowskiten rationalisiert und Abhängigkeiten der Kinetik von der Lösungskonzentration zeigen sich. Niedrige Konzentrationen führen zu einer beschleunigten Kristallisation und Schichtdickenabnahme des Nassfilms. Dieser Trend wird durch geringere Kolloidwechselwirkungen und niedriger koordinierte Blei-Bromid-Komplexe in verdünnten Lösungen erklärt. Die Korrelation im Präkursor-Prozess-Eigenschaftsraum hebt die Herstellung von Perowskiten aus chemischer Sicht zu einem nicht-trivialen Prozess.Bandgap tunability by ion substitution and the fabrication due to solution-based processes characterize metal halide perovskites. They are promising for application in various thin-film opto-electronic devices, which require the deposition of high-quality thin-films. The quality strongly depends on the crystallization behavior predetermined by the precursors in solution. This thesis aims to evaluate correlations in the vast precursor-process-property space of metal halide perovskite and rationalizes formation processes. Phase purity, morphology, and absorption properties determine the perovskite thin-film quality. The first part focuses on optimizing the perovskite fabrication to obtain high-quality films over a wide bandgap range. From high-quality films, the exciton binding energy is determined. The rationalization of formation processes proves essential to design reproducible preparation routines for high-quality films. The second part presents an optical in-situ setup to rationalize perovskite formation processes. Different formation pathways are taken, depending on the halide ratio in the MAPb(IxBr1-x)3 series. While the pure bromide forms directly and iodide-rich perovskites form via the intermediate solvate phase (MA)2(DMSO)2Pb3I8, mixed halides between 0.1 ≤ x ≤ 0.6 form via both. Such a heterogeneous formation process via two competing pathways rationalizes the compositional heterogeneity of mixed halide samples. The third part focuses on rationalizing the formation process of pure bromide perovskites and reveals a dependency of the formation kinetics on the solution concentration. Lower concentrations lead to accelerated crystallization kinetics and increase wet-film thinning. Lower colloid interaction and lower coordinated lead-bromide complexes in diluted solutions explain this trend. The strong correlation in the precursor-process-property space raises the preparation of perovskites via spin-coating to a non-trivial process from a chemical point of view.
5
Gao, Xiang. "Carboxylate Precursor Effects on MOD Derived Metal Oxide (Ni/NiO) Thin Films." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1331300391.
Повний текст джерела
6
Dill, Kathryn Ann. "Process Optimization for the Synthesis of Gold Nanoparticles from a Mixed Metal Precursor Solution." VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5326.
Повний текст джерелаАнотація:
Separation methods involving a mixture of metals typically include upfront processing that leads to one final product. To lower the waste and ultimately environmental burden, the potential to synthesize multiple functional products from a mixed metal precursor solution is explored. The initial precursor solutions contained varying ratios of gold and copper, gold and nickel, and finally a ternary solution of gold, copper, and nickel. The amount of gold was kept constant, while the amount of copper and/or nickel was sequentially increased. Two separate synthesis processes were tested, the traditional Turkevich method involving trisodium citrate and another chemical reduction method involving sodium borohydride. The particle size and chemical composition of the synthesized particles were characterized using TEM, DLS and ICP-OES. It was determined that gold nanoparticles still formed at a ratio of 1 to 2 gold to copper while using trisodium citrate or sodium borohydride as the reducing agent. The same limiting ratio was observed for the gold to nickel reactions in the presence of either trisodium citrate or sodium borohydride. The ternary mixture limit for gold nanoparticle formation was a molar ratio of 1 to 1 to 1 gold to copper to nickel. The repeatability and stability results for the optimized binary reaction conditions indicate that using sodium borohydride as the reducing agent consistently produces more stable particle suspensions. Quantifying the environmental impact using green chemistry metrics indicate the Turkevich reactions for the optimized reactions have the lower environmental factors.
7
Glatz, Christoph Johannes Germund. "From aminopyridinato complexes via metal containing SiCN precursor ceramics to heterogeneous recyclable oxidation catalysts." kostenfrei, 2009. http://opus.ub.uni-bayreuth.de/volltexte/2009/599/.
Повний текст джерела
8
Rehermann, Carolin [Verfasser]. "Exploring the Precursor-Process-Property Space in Metal Halide Perovskite Thin-Films / Carolin Rehermann." Berlin : Humboldt-Universität zu Berlin, 2021. http://d-nb.info/1238073964/34.
Повний текст джерела
9
Choujaa, Hamid. "Synthesis of novel single-source precursors for CVD of mixed-metal tungsten oxide." Thesis, University of Bath, 2008. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.478944.
Повний текст джерелаАнотація:
There is a considerable interest in the use of tungsten oxide in the research and development of new materials and devices, such as gas sensors and as photocatalysts. In order to improve the photocatalytic properties of WO3, its combination with metals which allows the preparation of WMxOy materials are believed to be promising photocatalysts under visible light. The present work deals with the synthesis of homo- and hetero-metallic tungsten alkoxide and amide compounds using the single source precursor approach for potential chemical vapour deposition precursors of mixed-metal oxide films.
10
Yu, Zexin. "Development and characterization of metal oxide semiconductor films deposited by solution precursor thermal spray process." Thesis, Bourgogne Franche-Comté, 2018. http://www.theses.fr/2018UBFCA036.
Повний текст джерелаАнотація:
Les procédés de photodégradation, de conversion photocatalytique du CO2 et la technologie des supercondensateurs représentent des options intéressantes pour palier aux problèmes environnementaux et pour apporter des réponses à la crise énergétique. Dans ces trois domaines, les matériaux à base d'oxydes métalliques sont très prometteurs. Cependant, les voies classiques (c'est-à-dire par voies hydrothermales ou de sol-gels) présentent un certain nombre d’inconvénients tels que leur longues durées de préparation et leurs rendements limités. En outre, la mise en oeuvre de nanopoudres suppose une opération de post-filtration dans les procédés de photodégradation et l’utilisation supplémentaire d’un liant dans la confection d’électrodes de supercondensateurs, ce qui non seulement réduit les performances respectives de ces deux procédés mais entrave également leur développement au niveau industriel. Dans cette thèse, les technologies SPPS (Solution Precursor Plasma Spray) et SPFS (Solution Precursor Flame Spray) ont été introduites pour préparer des films d'oxydes métalliques à base de ZnO, en bénéficiant des avantages de rapidité et simplicité de ces techniques de formation de dépôts. Les films ainsi obtenues ont ensuite été testés dans des expériences de photodégradation, de conversion photocatalytique du CO2 et sous forme de supercondensateurs. Tout d'abord, à notre connaissance, c'est la première fois que l'on synthétise directement des nanostructures de ZnO (par exemple des nanotubes ou des nanofils) par des procédés SPPS. Ces films nanostructurés et hiérarchisés présentent non seulement une croissance préférentielle le long du plan cristallin (002), mais contiennent aussi des lacunes d'oxygène dans leurs réseaux. La mise en œuvre de simulations DFT a permis de proposer un mécanisme possible de croissance des nanostructures de ZnO lors de leur synthèse par la voie SPPS. Deuxièmement, divers films “composites”, constitués de ZnO et d’un second oxide “MO” ont également été préparés par SPPS afin de réduire les bandes d'énergie interdites. Dans cette partie de la thèse, nous avons étudié l’effet du rapport molaire MO/ZnO sur la structure des films MO/ZnO obtenus (M = Mn et Cu); nous avons aussi préparé, par cette nouvelle méthode, des films fins CuO/ZnO et CeO2/ZnO ainsi que des films de ZnO “décorés”. Troisièmement, des films mettant en œuvre des structures du type spinelle (tels que les oxydes mixtes ZnFe2O4, NiCo2O4, ZnCo2O4 et Co3O4) ont également été synthétisés et déposés à l’aide des techniques SPPS et SPFS, ceci en raison de leur grand intérêt pour les applications susmentionnées. Il a été constaté que les structures obtenues sont très sensibles aux rapports MO/ZnO et que les morphologies de surface dépendent davantage des paramètres d'injection des solutions. En outre, la puissance de la torche joue un rôle plus critique dans la synthèse in situ de la phase spinelle binaire que la température de préchauffage du substrat. Enfin, la voie de préparation par SPPS favorise la formation de dépôts de textures floconneuses, notamment dans le cas des films de NiCo2O4 et Co3O4, tandis que des particules de formes sphériques ont été plutôt observées dans les échantillons préparés par la voie SPFSThe fields of research dealing with photodegradation, photocatalytic conversion of CO2 and supercapacitors are important to address environmental problems and respond to the energy crisis. Metal oxides are promising materials in these three domains. However, the conventional routes (i.e. hydrothermal, sol-gel) suffer from major deficiencies, namely their multi-step natures, their long preparation duration and small-scaled yields. Moreover, the usage of nanopowders implies a post-filtration operation at the end of the photodegradation processes and requires an additional binder in supercapacitor electrodes. In this thesis, “Solution Precursor Plasma Spray” (SPPS) and “Solution Precursor Flame Spray” (SPFS) technologies have been introduced to develop metal oxide films in view of the three aforementioned applications, benefiting from the facility and rapidity advantages of this one-step process.Firstly, to our best knowledge, it is the first time that films composed by ZnO nanostructures (e.g. nanorods, nanowires) are directly synthesized via a SPPS process. These hierarchical ZnO nanostructured films not only exhibit preferential orientation growth along the (002) crystal plane, but also feature in-situ oxygen vacancies. As a result, a possible growth mechanism of ZnO nanostructures via SPPS route was proposed.Secondly, various metal oxides composite films containing ZnO and a second metal oxide were also prepared by SPPS in an effort to narrow the energy bandgaps. In this work, not only the effect of the molar CuO/ZnO and MnO/ZnO ratio was investigated, but also laminated CuO/ZnO and CeO2/ZnO films and CuO, Co3O4 and Fe2O3 decorated ZnO nanorods films were pioneeringly deposited via this novel route.Thirdly, films involving spinel-type materials (including ZnFe2O4, NiCo2O4, ZnCo2O4 and Co3O4) were also synthesized and deposited by the SPPS and SPFS technologies, owing to their high-interest in the aforementioned applications. We found that the phase compositions are more sensitive to the Fe/Zn and Ni/Co ratios and that the surface morphologies are more dependent on the patterns of the solution injection. In addition, the power of the torch plays a more critical role on the in-situ synthesis of binary spinel phase. Besides, the SPPS route promotes the formation of flake-like particles both in the NiCo2O4 and Co3O4 films, while sphere-like particles were observed in the SPFS-prepared samples.Finally, some as-prepared films were selected to evaluate their performances within the three applications. On the one hand, Orange II was successfully (100%) degraded within 2h under UV irradiation and about 85% was removed within 6h under visible light irradiation. On the other hand, Co3O4 samples exhibited specific capacitances up to 1190 F g−1 with a retention capacity of 136% after 2500 cycles at a 20 mV/s scanning rate in 2 M KOH electrolyte. Finally, when using ZnCo2O4 as photocatalyst, CO2 was converted into CO by visible light irradiation with a maximum turnover number as high as 61.38 and a selectivity as high as 90.5 %.Overall, this work not only improves the performances of the three studied processes thanks to the use of novel, fast preparation methods, but also suggests that “Solution Precursor Thermal Spray” should be a highly promising technology for further, alternative functional applications that involve finely structured metal oxides film
11
Kondo, Hiroki, Shinnya Sakurai, Mitsuo Sakashita, Akira Sakai, Masaki Ogawa, and Shigeaki Zaima. "Metal-organic chemical vapor deposition of high-dielectric-constant praseodymium oxide films using a cyclopentadienyl precursor." American Institute of Physics, 2010. http://hdl.handle.net/2237/14181.
Повний текст джерела
12
Soussi, Khaled. "Precursor chemistry of novel metal triazenides : Solution and vapor phase elaborations of Fe and Al13Fe4 nanomaterials." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1006/document.
Повний текст джерелаАнотація:
La production de polyéthylène par la polymérisation de l'éthylène est un procédé industriel de grande importance. L'éthylène, issue de la pétrochimie contient des impuretés d'acétylène (1%), ce qui empoisonne le catalyseur de polymérisation, et donc le besoin d'un catalyseur qui soit sélectif pour hydrogéner l'acétylène en éthylène. Le composé intermétallique Al13Fe4 a été développé par Armbuster et al. en 2012 comme un catalyseur actif et sélectif pour la semi-hydrogénation de l'acétylène pour la production de polyéthylène. Il présente une structure cristalline avec des distances interatomiques Fe-Fe élevées et un faible nombre de coordination des atomes de fer, qui tombe sous le concept de "site isolation principle". Ce composé est également intéressant en raison de son faible coût (sans métaux nobles par rapport à Pd /Al2O3 catalyseurs industriels) et une faible toxicité. Cependant, il a été produit sous la forme de poudre non supportée par la méthode Czochralski ce qui limite son utilisation dans le domaine du génie catalytique. Dans ce contexte, supporter le catalyseur présente de nombreux avantages comme la facilité de séparation du catalyseur hétérogène à partir du mélange réactionnel obtenue par une variété de procédés telle que la filtration par exemple. Un autre avantage des catalyseurs supportés est la plus grande surface exposée du catalyseur ou dispersion. Etant donné que la catalyse est une réaction de surface, maximiser la surface d'un catalyseur, en le dispersant sur le support améliorera / optimisera l'activité catalytique. Les procédés de "chimie douce" dénommés Metal Organic Chemical Vapor Deposition (MOCVD) et Metal Organic Deposition (MOD) sont réputés pour être efficaces et économiquement compétitifs pour déposer des nanoparticules ou des films minces, à partir de précurseurs moléculaires appropriés. Notre travail vise donc à développer Al13Fe4 sous forme de films ou de nanoparticules supportées par MOCVD. La première étape pour atteindre cet objectif est le développement des précurseurs moléculaires d'aluminium métallique et de fer, dans des conditions compatibles suivies par codépôt ou dépôt séquentiel des deux précurseurs de Fe et Al pour former le composé intermétallique dans la bonne stœchiométrie. Parmi les nombreux précurseurs d'Al, le diméthyl ethylaminealane (DMEAA, [AlH3(NMe2Et)]) est utilisé en raison de sa pression de vapeur importante et des températures de dépôt faibles. En outre, l'absence de liaisons Al-O et Al-C conduit à la production de films sans impuretés carbone et oxygène. Cependant, des précurseurs moléculaires de fer pour le dépôt pour MOCVD de films de fer purs sont rares et moins développés. En dehors du pentacarbonyle de fer qui produit des films de fer pur, amidinates et guanidinates sont utilisés comme précurseurs de fer. Cependant, l'oxygène et des carbures sont présents dans des pourcentages élevés. Ainsi, l'objectif principal de ce travail de thèse est de concevoir et de synthétiser de nouveaux complexes moléculaires de fer qui servent de précurseurs pour la MOCVD. Dans ce travail, des nanoparticules de composé intermétallique Al13Fe4 sont préparées par réduction en solution et des films par dépôt séquentiel MOCVD en utilisant DMEAA et Fe(CO)5 en tant que précurseurs moléculaires. Les propriétés catalytiques ont été étudiées et ont montré d'une activité très peu active dans la réaction d'hydrogénation de l'acétylène: moins de 1% avant de se désactiver rapidement. La régénération sous hydrogène ou sous oxygène n'a qu'une faible restauration de l'activité. Les tests catalytiques ont été encore étendus à Al13Fe4 poudre préparée par réduction en solution ainsi que Al13Fe4 en poudre commerciale et a constaté que Al13Fe4 était non catalytiquement actif sous toutes ses formes (dans nos conditions de réaction)Polyethylene production from the polymerization of ethylene is an industrial process of great importance. Ethylene stream for the polymerization of polyethylene is produced by the steam cracking of a wide range of hydrocarbon feedstock and usually contains acetylene impurities (1%) which poison the polymerization catalyst. The ethylene steam has to be purified by the selective semi-hydrogenation of acetylene which requires a catalyst with high selectivity to hydrogenate acetylene to ethylene. The intermetallic compound Al13Fe4 was introduced in 2012 by Armbuster et al. as an active and selective catalyst for the semi-hydrogenation of acetylene for polyethylene production. It has a crystal structure with high average inter-atomic distances Fe-Fe and a low coordination number of iron atoms, which falls under the concept of "site isolation principle". This compound is also attractive because of its low cost (without any noble metals compared to Pd/Al2O3 industrial catalysts) and low toxicity. However, it has been produced in the form of unsupported powder by the Czochralski method which limits its use in catalytic engineering. In this context, supporting the catalyst presents many advantages as the ease of separation of the heterogeneous catalyst from the reaction mixture. In contrast to homogeneous catalysts in which separation is often costly and difficult, separating the supported heterogeneous catalyst can be achieved by a variety of methods such as filtration for example. Another advantage of supported catalysts is the higher surface area of the catalyst. Since catalysis is a surface reaction, consequently, maximizing the surface area of a catalyst by distributing it over the support will enhance/optimize the catalytic activity.Chemical synthetic routes such as Metal Organic Chemical Vapor Deposition (MOCVD) and Metal Organic Deposition (MOD) referred as “Chimie douce” process are reputed to be flexible and economically competitive methods to prepare nanoparticles or thin films. Our work is thus aimed at developing Al13Fe4 as supported films or nanoparticles by MOCVD and/or MOD. The first step to meet our objective is the development of compatible molecular precursors of metallic aluminum and iron followed by MOCVD or MOD of those precursors to form the intermetallic compound in the good stoichiometry. Among the numerous aluminum MOCVD precursors used in the literature, dimethyl ethylamine alane (DMEAA, [AlH3(NMe2Et)]) is used due to its properties such as high vapor pressure and low deposition temperatures. Moreover, the absence of Al-O and Al-C bonds leads to the production of carbon and oxygen free films. However, iron molecular precursors for the MOCVD of pure iron films are scarce and less developed. Apart from iron pentacarbonyl that produces pure iron films, amidinates and guanidinates are used as iron precursors. However, oxygen and carbides impurities are present in high percentages. Thus the main objective of this Ph-D work is to design and synthesize novel and original iron molecular complexes that serve as precursors for the low temperature MOCVD of iron films. In this Ph-D work, nanoparticles of the intermetallic complex were prepared via solution reduction of novel Fe triazenide precursors and Al metal. Supported films were also prepared via sequential MOCVD by using DMEAA and Fe(CO)5 as molecular precursors. Its catalytic properties have been explored and showed that it is very little active in the hydrogenation reaction of acetylene. Regeneration under hydrogen or oxygen was not very successful and only some activity restored. The catalytic tests have been further extended to Al13Fe4 powder prepared by solution reduction as well as to commercial Al13Fe4 and found that Al13Fe4 was inactive catalytically in all forms (in our conditions of reactions)
13
Parala, Harish. "Precursor routes to selected metal and semiconductor nanomaterials crystals, composites, colloids of Au, GaN, InN, CdSe and TiO₂ /." [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=96870901X.
Повний текст джерела
14
Parala, Harish. "Precursor routes to selected metal and semiconductor nanomaterials crystals, composites, colloids of Au, GaN, InN, CdSe and TiO2 /." [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=96870901X.
Повний текст джерела
15
Sen, Selda. "Activity Of Carbon Supported Platinum Nanoparticles Catalysts Toward Methanol Oxidation Reaction: Role Of Metal Precursor And A New Surfactant." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/3/12609273/index.pdf.
Повний текст джерелаАнотація:
In this thesis, carbon supported platinum nanoparticle catalysts were prepared using PtCl4 and H2PtCl6 as starting materials and 1-heptanethiol, tert-nonyl mercaptan, 1-hexadecanethiol, 1-octadecanethiol as surfactants. These new catalysts were employed for methanol oxidation reaction which are used for direct methanol fuel cells. Tert-nonyl mercaptane was used for the first time in this type of reaction and the other surfactants were used for comparison of the catalysts performance. Cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used in order to determine the nature of the catalysts.
The average platinum crystallite particle sizes of all prepared catalysts were determined by both X-ray diffraction and transmission electron microscopy. It was found that platinum crystallizes in face-centered cubic structure and the surfactant play an important role on the size of platinum nanoparticles, branch surfactant, such as tert-nonyl mercaptane, causes an increase in the size of platinum nanoparticles, about 3 nm, compared to linear surfactant, such as 1-heptanethiol, about 2 nm.
The oxidation states of platinum and their ratios were determined by XPS technique. These results indicated that platinum has two different oxidation states, zero and +4, and Pt(0) to Pt(IV) ratio is about 7.5 to 2.5. In addition to this, O 1s region of XPS was also examined and found that the surface of all of the catalysts covered by adsorbed hydroxide except the catalyst which was prepared by PtCl4 and tert-nonyl mercaptane (Catalyst IIa), where adsorption of water were observed and the catalyst which was prepared by H2PtCl6 and tert-nonyl mercaptane (Catalysts IIb), where adsorption of 65% of hydroxide and 35% of water were identified.
Electrochemical studies indicated that Catalyst IIa has the maximum activity (
342 A/gPt at 0.612 V) towards methanol oxidation reaction while Catalyst IIIb (H2PtCl6 and 1-hexanethiol were used to prepare this catalyst) has the minimum activity (&
#61566
91A/gPt at 0.580V). XRD, TEM and XPS results indicated that the optimum catalyst for methanol oxidation reaction contains about 3 nm of platinum nanoparticles, adsorbed hydroxide and water on the surface of catalyst, but sulphur. These results are in agreement with the proposed mechanism.
16
Zhou, Cong [Verfasser], Ralf [Akademischer Betreuer] Riedel, and Zhaoju [Akademischer Betreuer] Yu. "Ternary Si-Metal-N Ceramics: Single-Source-Precursor Synthesis, Nanostructure and Properties Characterization / Cong Zhou ; Ralf Riedel, Zhaoju Yu." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2017. http://d-nb.info/1130323242/34.
Повний текст джерела
17
Kim, Jiyeon [Verfasser], Roland A. [Gutachter] Fischer, and Anjana [Gutachter] Devi. "Organometallic chemistry of transition metal-group 13 complexes and metal-organic precursor synthesis for ALD cobalt oxide thin films / Jiyeon Kim ; Gutachter: Roland A. Fischer, Anjana Devi." Bochum : Ruhr-Universität Bochum, 2017. http://d-nb.info/1144613949/34.
Повний текст джерела
18
Denmeade, Joshua J. "Investigation of Novel Precursor Routes for Incorporation of Oxynitride Spinel Phases into Ceramic-Metallic Composites Formed via the TCON Process." Youngstown State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1391684337.
Повний текст джерела
19
Abdelhady, Ahmed Mohammed Said lutfi. "Developing novel processes in chemistry for several types of nanoparticles." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/developing-novel-processes-in-chemistry-for-several-types-of-nanoparticles(0712d3c6-e2d5-415a-b787-c9ce457e1355).html.
Повний текст джерелаАнотація:
The work presented in this thesis reports the use of a series of novel thiobiuret metal complexes [M(SON(CNiPr2)2)n] (M = Cu, Ni, Fe, Zn, Cd or In; n = 2 or 3) for the first time as single source precursors for the colloidal synthesis of metal sulfide nanoparticles. Other single source precursor(s) were also used for the synthesis of CdSe, CdS, CdSe/CdS core/shell, CdSeS alloys and Cu2-xS nanoparticles in microfluidic reactors. Thermolysis experiments of [Cu(SON(CNiPr2)2)2] using only oleylamine produced Cu7S4 nanoparticles as a mixture of monoclinic and orthorhombic phases. Pure orthorhombic Cu7S4 nanoparticles were obtained when a solution of precursor in octadecene was injected into hot oleylamine whereas, Cu1.94S nanoparticles were obtained when a solution of the precursor in oleylamine was injected into hot dodecanethiol. The thermolysis of [Ni(SON(CNiPr2)2)2] gave Ni3S4 in all cases except when precursor solution in oleylamine was injected into hot octadecene which produced NiS nanoparticles. The thermolysis of [Fe(SON(CNiPr2)2)3] in oleylamine/oleylamine produced Fe7S8 nanoparticles but other combinations, in most cases, gave amorphous material. Thermolysis of [Zn(SON(CNiPr2)2)2] in oleylamine produced spherical ZnS nanoparticles. Particles with size smaller than 4.3 nm had a cubic phase, whereas the particles with size larger than 4.3 nm had a hexagonal crystal structure as suggested by the selected area electron diffraction. Powder X-Ray diffraction showed that the CdS nanoparticles obtained from the thermolysis of [Cd(SON(CNiPr2)2)2] in oleylamine were cubic under all reaction conditions except when dodecanethiol was used as an injection solvent which produced hexagonal CdS. β-In2S3 were synthesized from the thermolysis of [In(SON(CNiPr2)2)3]. Transmission electron microscopy showed that the copper, nickel and iron sulfide nanoparticles had various morphologies such as spherical, hexagonal disks, trigonal disks, rods or wires; depending on the reaction temperature, concentration of the precursor, the growth time and the solvent/capping agent combination. The zinc and cadmium sulfide nanoparticles were mostly spherical whereas the indium sulfide nanoparticles were produced in the form of ultra-thin (< 1.0 nm) nanorods or nanowires. ZnxCd1-xS and CuInS2 nanoparticles were synthesised from the 1,1,5,5-tetra-iso-propyl-4-thiobiureto complexes of Zn, Cd and Cu, In, respectively. Powder X-Ray diffraction showed that the obtained ZnxCd1-xS nanoparticles are cubic under all reaction conditions. The ZnxCd1-xS nanoparticles had an average diameter between 3.5 to 6.4 nm as shown by transmission electron microscopy. The optical properties of the ZnxCd1-xS nanoparticles were highly dependent on the ZnS to CdS precursor ratio and the solvents/capping agents. Chalcopyrite (tetragonal), wurtzite (hexagonal) or a mixture of both CuInS2 nanoparticles were obtained depending on the reaction conditions. TEM showed that the CuInS2 nanoparticles could be synthesised with different morphologies (spherical, hexagonal, trigonal or cone). Luminescent CuInS2 nanoparticles were obtained only in the absence of oleylamine. [Cd(S2CNMenHex)2], [Cd(Se2P(iPr)2)2] and [Cu(SON(CNiPr2)2)2] were used as single source precursor(s) for the synthesis of CdS, CdSe, CdSe/CdS core/shell, CdSeS alloys and Cu2-xS in microfludic reactor. The CdS nanoparticles were in size range of 5.0 to 8.0 nm whereas the CdSe nanoparticles were ultra small (ca. 2 nm) with blue luminescence. The CdSe/CdS core/shell and the CdSeS alloys were bluish green or green luminescent depending on their size. The copper sulfide nanoparticles were found to be monoclinic Cu7S4 or monoclinic Cu7S4 with minor impurities of rhombohedral Cu9S5 depending on the reaction conditions.
20
Ramunno, Monica V. "Preparation and Characterization of Spinel-based Interpenetrating Phase Composites via Transformation of 3-D Printed Precursor Shapes." Youngstown State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1472555655.
Повний текст джерела
21
Dumbrell, Kathy. "Athlone in the early twentieth century - a precursor to working class housing on the Cape Flats, 1900-1930." Bachelor's thesis, University of Cape Town, 1998. http://hdl.handle.net/11427/5607.
Повний текст джерелаАнотація:
Bibliography: leaves 56-58.The initial work for this project was a photographic survey of the existing wood and iron buildings in Athlone. I was at the time a volunteer in the Urban Conservation Unit of the Cape Town City Council (hereafter UCU). My task was to docment the existing wood-and-iron buidlings in order to aid later development control decision-making. to a large extent, it was the results of the fieldwork, which both uncovered a need for further research and directed later archival and textual research.
22
Brazda, Petr. "Preparation of Fe2O3/SiO2 nanocomposites from molecular precursor by the sol-gel method and the doping of iron (III) by trivalent metal cations." Strasbourg, 2009. http://www.theses.fr/2009STRA6289.
Повний текст джерелаАнотація:
Les travaux que nous présentons dans cette thèse se concentrent sur la préparation de nanocomposite de silice sol-gel amorphe comme matrice de synthèse de nanocristaux de epsilon-Fe2O3 purs. La souplesse du procédé de synthèse nous a permis d’envisager et de réaliser la substitution partielle et raisonnée du fer par l’aluminium et gallium. Pour cela nous avons élaboré les nanocomposites Al0. 25Fe1. 75O3/SiO2, Al0. 50Fe1. 50O3/SiO2, Al0. 75Fe1. 25O3/SiO2, Ga0. 25Fe1. 75O3/SiO2, Ga0. 50Fe1. 50O3/SiO2 and Ga0. 75Fe1. 25O3/SiO2. Nous avons pu grâce à la maitrise de la synthèse du précurseur et des traitements thermiques raisonnés déterminer les conditions optimales permettant de préparer presque pure une phase métastable de l’oxyde de fer, la phase e-Fe2O3. La majorité d'échantillons substitués n'a pas contenu d'autre que la phase epsilon. Les mesures de spectroscopie par RMN à 4. 2K nous ont permis de voir sous un autre angle les attributions des sous spectres de spectroscopie Mössbauer et d’expliquer plus finement le lien entre données structurales et propriétés magnétiques de epsilon-Fe2O3Presented work is focused on preparation of nanocomposite of epsilon-Fe2O3 crystallites embedded in amorphous SiO2 matrix using new sol-gel technique. Another aim of our study was to prepare epsilon iron(III) oxide with part of iron atoms substituted by diamagnetic aluminium or gallium atoms. From this reason nanocomposites of compositions of Al0. 25Fe1. 75O3/SiO2, Al0. 50Fe1. 50O3/SiO2, Al0. 75Fe1. 25O3/SiO2, Ga0. 25Fe1. 75O3/SiO2, Ga0. 50Fe1. 50O3/SiO2 and Ga0. 75Fe1. 25O3/SiO2 were prepared. Thanks to the optimal conditions, the non-substituted samples prepared were very pure. The majority of substituted samples did not contain other than epsilon phase. The anisotropy of hyperfine fields at 4. 2 K observed by NMR spectroscopy led to an alternative assignment of the subspectra in Mössbauer spectrum of epsilon phase. Fine structure of Mössbauer spectra induced by the substitution permitted a deeper understanding of the relationship between structure and magnetic properties of epsilon-Fe2O3
23
Myers, Kyle M. "Investigation of Novel Precursor Routes for Incorporation of Titanium Alloys and Nano-Sized Features into Ceramic-Metallic Composites Formed via the TCON Process." Youngstown State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1365507702.
Повний текст джерела
24
Du, Guodong. "Group 4 Metalloporphyrin diolato Complexes and Catalytic Application of Metalloporphyrins and Related Transition Metal Complexes." Washington, D.C. : Oak Ridge, Tenn. : United States. Dept. of Energy. Office of Science ; distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2004. http://www.osti.gov/servlets/purl/835301-irsXCw/webviewable/.
Повний текст джерела
25
Erbe, Manuela, Jens Hänisch, Thomas Freudenberg, Anke Kirchner, Stefan Kaskel, Ingolf Mönch, Ludwig Schultz та Bernhard Holzapfel. "Improved REBa₂Cu₃O₇₋ₓ (RE ═ Y, Gd) structure and superconducting properties by addition of acetylacetone in TFA-MOD precursor solutions". Royal Society of Chemistry, 2014. https://tud.qucosa.de/id/qucosa%3A36162.
Повний текст джерелаАнотація:
For developing commercially utilized high-performance high-temperature superconductors, the fabrication of biaxially textured (RE)Ba₂Cu₃O₇₋ₓ (REBCO, RE ═ Y, Gd) coated conductors via metal–organic decomposition of trifluoroacetate precursors (TFA-MOD) has become an interesting strategy for industrial scale-up due to low costs and simple operation. However, the hygroscopic nature of commonly used precursor solutions makes them very sensitive to water pollution through air humidity. This can lead to a degradation of the final microstructure, which in return deteriorates critical current densities. Here, we present a new method to overcome that problem by using a moderator of 2,4-pentanedione (acac) in a pre-existing REBCO precursor solution. Our results show that even initially low-performance solutions can be enhanced to such an extent that they finally outperform standard high-performance solutions and the temperature window for their optimal growth widens significantly. Scanning electron microscopy gives evidence of considerable microstructural improvements, e.g. avoidance of pore formation and grooves, reduction of buckling and surface granularity. X-ray investigations indicate texture improvements, and electrical measurements reveal that transport critical current densities (Jc) increase in self-field and applied magnetic fields. For YBCO, a molar ratio of acac/RE ═ 0.64 is most effective and leads to an increase of the maximum pinning force density Fmaxp from 1.0 to 2.4 GN mˉ³ at 77 K. For GdBCO, a broad window of annealing temperatures (790–840°C) is possible for films with Jc values above 2.9 MA cmˉ² and Fmaxp above 3 GN mˉ³ at 77 K.
26
Young, Kay. "Mixed metal alkoxides as catalyst precursors." Thesis, Durham University, 1989. http://etheses.dur.ac.uk/6528/.
Повний текст джерелаАнотація:
This thesis describes research carried out to explore the use of mixed metal alkoxides as precursors of materials with catalytic activity in synthesis-gas chemistry. The alkoxide derived catalyst materials are compared against catalysts prepared by traditional co-precipitation methods. A discussion of the project objectives introduces the work and Chapter 1 includes a chronological survey of the literature up to the present day. A brief discussion of the commercial uses of alkoxides is given. Chapter 2 describes the general methods of synthesis and the properties of simple and bimetallic alkoxides; M(OR)(_x) and M[M'(OR)(_n)](_x) respectively. A more detailed treatment of the alkoxides of the first row transition elements is given, with emphasis on the properties and characteristics responsible for their possible potential as catalyst precursors. Chapter 3 deals with the catalytic aspects of ammonia and methanol synthesis. The preparation of industrial, heterogeneous catalysts has traditionally been carried out by co-precipitation of, for example, basic carbonates. The catalytic materials obtained may display catalytic activities which vary markedly (and not always controllably) with the precipitation, ageing, calcinations and/or reduction conditions employed. A discussion of the reaction mechanisms involved in ammonia and methanol syntheses is included. Several mixed metal alkoxides have been prepared from metals known to have catalytic activity in synthesis-gas chemistry (i.e. Mn, Fe, Co, Cu, Zn and Al). These metal alkoxides (e.g. Cu[Al(OPr(^1) (_4)](_2) ) have been characterised and found to compare well with literature data. Analyses, Infra-red and Mass-spectra are reported. After conversion to catalytic materials the alkoxide derived compounds were examined for surface properties ( oxide phases present, copper surface area, crystallite size, pore size distributions and pore volumes). The alkoxide materials compared quite well with the precipitated analogues and there was a difference in the properties of materials derived from different alkoxy groups. These studies were limited to the copper-aluminium alkoxides. The formation of a nickel (II) chloride, HMPA adduct is reported.
27
McAtamney, Karen Marie. "Transition metal aryloxides as ferrite precursors." Thesis, Queen's University Belfast, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326372.
Повний текст джерела
28
Catherall, Amanda Louise. "(Thio)amidate precursors to metal chalcogenides." Thesis, University of Bath, 2017. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760913.
Повний текст джерела
29
Ramasamy, Karthik. "New molecular precursors for metal sulfides." Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/new-molecular-precursors-for-metal-sulfides(49bcd8c0-4a37-4eb1-892e-7a7973f8f3cd).html.
Повний текст джерелаАнотація:
Metal sulfide thin films are important class of materials which have applications in photovoltaics, microelectronics and displays. Chemical vapour deposition (CVD) is well known method for the deposition of high quality thin films. Very few classes of single source precursors (eg: dithiocarbamates, xanthates) were successful for the deposition of good quality metal sulfide films by MOCVD. This limited choice was due to the difficulties of finding precursors with suitable physico-chemical properties. Hence, it is important to develop precursors with suitable volatility, solubility and being able to deposit films with little or no contamination. This work describes the synthesis of a series of metal (Fe, Co, Ni, Zn, Cd) complexes of thio- and dithio-biuret ligands, their structural and spectroscopic characterization and thermal decomposition. The complexes were used as single source precursors for the deposition of iron, cobalt, nickel, zinc, cadmium and zinc cadmium sulfide thin films by AACVD. The effect of alkyl groups, coordinating atoms, deposition temperatures on phases and morphology of the films were studied. The deposited films were characterised by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and atomic force microscopy (AFM). The complex [Fe(SON(CNiPr2)2)3] gave hexagonal troilite FeS films with small amount of tetragonal pyrrhotites Fe1-xS at 300 °C, whereas only troilite FeS was deposited at 350, 400 or 450 °C. Complexes [Fe2(µ-OMe)2 (SON(CNEt2)2)2] and [Fe(SON(CNEt2)2)3] deposited a mixture of hexagonal troilite FeS and cubic pyrite FeS2 films at all temperatures. [Fe(SON(CNMe2)2)3] deposited very thin films of FeS at all temperatures as troilite. Complexes [Co(N(SCNMe2)2)3] and [Co(N(SCNEt2)2)3] deposited hexagonal Co1-xS films at all temperatures of 350-500 °C, whereas [Co(SON(CNiPr2)2)2] gave mixture of cubic and hexagonal Co4S3 films at 280-400 °C. Thiobiuret complex [Ni(SON(CNMe2)2)2] gave orthorhombic Ni7S6. Complexes [Ni(SON(CNMe2CNEt2))2] and [Ni(SON(CNEt2)2)2] gave mixtures of hexagonal Ni17S18 and orthorhombic Ni7S6. In contrast, [Ni(SON(CNiPr2)2)2] gave orthorhombic Ni9S8. Dithiobiuret complexes [Ni(N(SCNMe2SCNEt2))2] and [Ni(N(SCNEt2)2)2] gave hexagonal NiS1.03 at 360 and 400 °C, orthorhombic Ni7S6 phase at 440 and 480 °C. The zinc complexes [Zn(N(SCNMe2)2)2] and [Zn(SON(CNiPr2)2)2] deposited cubic ZnS at 300 and 350 °C, whereas at 400 and 450 °C hexagonal ZnS were apparent [Zn(N(SCNEt2)2)2] gave hexagonal ZnS films at all deposition temperatures. Cadmium complexes [Cd(N(SCNMe2)2)2], [Cd(N(SCNEt2)2)2] and [Cd(SON(CNiPr2)2)2] gave hexagonal CdS films at all deposition temperatures.
30
Fan, Haibo. "HfC structural foams synthesized from polymer precursors." Auburn, Ala., 2005. http://repo.lib.auburn.edu/2005%20Fall/Dissertation/FAN_HAIBO_30.pdf.
Повний текст джерела
31
Veitch, Charles D. "The preparation of polycrystalline mixed-metal oxide phases from metal-organic precursors." Thesis, Glasgow Caledonian University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335019.
Повний текст джерела
32
Marsh, Patrica Ann. "Metal complexes as precursors for film deposition processes." Thesis, Open University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262973.
Повний текст джерела
33
Linney, Rachel E. "The laser powered pyrolysis of metal deposition precursors." Thesis, University of Leicester, 1993. http://hdl.handle.net/2381/33788.
Повний текст джерела
34
Hayward, James. "Supported metal catalysts for the production of chemical precursors." Thesis, Cardiff University, 2013. http://orca.cf.ac.uk/53589/.
Повний текст джерелаАнотація:
Supported metal catalysts have applications across a broad range of industrial processes. The metal species are often the active catalysts in these processes, but supporting these materials upon a different material can produce desirable characteristics in the overall catalyst. These effects can include, but are not limited to, increased dispersion of active material, increased stability of the active material, and, depending on the supporting material, beneficial metal-support interactions can be generated. The production of benzaldehyde from benzyl alcohol is a reaction with high commercial value. Gold-palladium catalysts have been shown to be effective at production of benzaldehyde from benzyl alcohol under relatively mild, solvent-free conditions. It has also been shown that the selectivity of this reaction is dependent upon the acidic or basic character of the support material. Perovskites are a class of highly stable minerals with a general formula of ABO3, with A being a cation with a larger ionic radius than B. The acidic and basic character of a perovskite is strongly determined by the nature of the A cation, which allows for the possibility of adjusting this character by metal substitution. This study investigates the effects of gradual substitution of lanthanum for strontium in vanadate perovskites, and showed that incorporation of the substituted metal is effective up to a certain point, beyond which the material switches to two spate perovskite phases. The substitution of the metal ions was shown to have an effect on the acidic and basic properties of the perovskite materials using the Isopropyl Alcohol (IPA) reaction, which forms different products on acidic or basic sites. Following this, substitution with a wider range of group II metals was investigated and tested, both in the IPA reaction and as supports for precious metals in the production of benzaldehyde. A separate series of investigations were performed on Fischer-Tropsch (FT) catalysts. Fischer-Tropsch is a name given to a wide range of catalytic processes involving the production of hydrocarbons from a mixture of carbon monoxide and hydrogen, known as syngas. The formation of products is generally believed to proceed through a chain-lengthening process using single-carbon units. This leads to a broad distribution of products Abstract as opposed to a single highly selective product, and the selectivity pattern is often described using the Shulz-Florey-Anderson distribution. Much of the work on FT catalysts is involved in modifications of the catalyst system to produce a tighter distribution of products. In this study a series of investigations have been made into the effects that variations of the preparation method of CoMnOx supported on activated carbon. The basic preparation is an impregnation method, and several changes in catalyst activity and selectivity were observed following changes to this. An investigation into the effects of altering the amount of manganese relative to cobalt in the system also highlighted several trends, leading to a greater understanding of the factors affecting the conversion and selectivity of the catalyst system. A separate are of research in FT-style reactions is the production of alcohols from syngas, typically at higher pressures. As in the previous section, these an attempt was made to improve the activity and selectivity of these catalysts by alterations to the preparation methods, and also by alteration of the amount of secondary metal relative to cobalt. The catalysts used in these investigations consisted of CoMoOx supported on activated carbon. The standard preparation used a coprecipitation method based upon a similar method used for the production of CoMoS2 catalysts, which were also investigated in this study. Later investigations, notably those in which the amount of molybdenum relative to cobalt was altered, were prepared using an impregnation method. A series of improvements to a base catalyst were achieved by alteration to the preparation conditions, but more substantial improvements were observed when the alteration of the metal ratios was investigated. With regards to the use of activated carbon as a support material, it was also observed that it was possible to bring about the reduction of the cobalt species, and to a lesser extent the manganese and molybdenum species, by heating the catalysts to a high temperature in an inert atmosphere, namely helium.
35
Kamada, Rui. "Copper(indium,gallium)selenide film formation from selenization of mixed metal/metal-selenide precursors." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 226 p, 2009. http://proquest.umi.com/pqdweb?did=1654501631&sid=4&Fmt=2&clientId=8331&RQT=309&VName=PQD.
Повний текст джерела
36
Trindade, Tito Da Silva. "The synthesis of metal chalcogenide nanocrystallites using single molecule precursors." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363125.
Повний текст джерела
37
Hermans, S. "Mixed-metal clusters as precursors for bimetallic supported nanoparticle catalysts." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.603977.
Повний текст джерелаАнотація:
This thesis describes in a first part the synthesis of new mixed-metal clusters of ruthenium in association with palladium, platinum and tin. The use of monometallic dichloro complexes of Pd or Pt in reactions with negatively charged penta- or hexaruthenium clusters in the presence of a chlorine scavenger has been moderately successful in the case of Pd, but highly successful in the case of Pt. High yields were obtained in many instances. The mixed clusters [Ru5C(CO)14Pt(COD)], [Ru6C(CO)16Pt(COD)], [Ru6C(CO)15(Pt(COD))2] and [{Ru6C(CO)16}2Pt(MeCN)2] were characterised by X-ray crystallography. On the other hand, the use of [Pt(PPh3)4] allowed the isolation and structure determination of [Ru6C(CO)16PPh3] rather than mixed species. The reactivity of [Ru5C(CO)14Pt(COD)] and [Ru6C(CO)16Pt(COD)] with CO, PPh3 and dppm was investigated, and led to the isolation of other mixed-metal and homometallic compounds. The crystal structures of the clusters [Ru5C(CO)11Pt(CO)(dppm)2], [Ru6C(CO)13(dppm)2] and [Ru6C(CO)16Pt3(dppm)2] were determined. Several Ru-Sn mixed clusters were also synthesised, and in particular reactions involving [PPN]2[Ru6C(CO)16] and SnCl4 led to the isolation of [PPN][Ru6C(CO)16SnCl3] and [Ru6C(CO)16SnCl2], which were characterised crystallographically. In a second part, some of the new mixed-metal clusters were used as precursors for nanoparticle heterogeneous catalysts, using the mesoporous silica MCM-41 or carbon nanotubes as supports. A Ru-Pd/MCM-41 catalyst derived from a Pd6Ru6 cluster was shown to be extremely active for the hydrogenation of alkenes to alkanes and of naphthalene to cis-decalin selectively. This material was characterised by STEM and in situ FTIR and EXAFS, which confirmed the bimetallic nature of the nanoparticles and their homogeneous small sizes and dispersion on the support. The shape of the nanoparticles was further assessed by theoretical calculations. A Ru-Sn/MCM-41 catalyst was prepared from [PPN][Ru6C(CO)16SnCl3] and shown to hydrogenate selectively cyclic poly-enes to their mono-enes, under solvent-free and low temperature conditions. This catalyst was also characterised by STEM and in situ FTIR and EXAFS, which indicated that the tin atom is the anchoring point for the bimetallic nanoparticles on the siliceous walls of MCM-41. Finally, the clusters [Ru5C(CO)14Pt(COD)], [Ru6C(CO)16Pt(COD)], [PPN][Ru6C(CO)16SnCl3] and [Ru6C(CO)16SnCl2] were used as ideal precursors for small-sized and evenly dispersed bimetallic nanoparticles supported on carbon nanotubes.
38
Tobin, Neil Lawrence. "Improved precursors for the chemical vapour deposition of metal oxides." Thesis, University of Liverpool, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417972.
Повний текст джерела
39
Ogrodnik, Virginie. "Silver complexes having potential as precursors for metal film deposition." Thesis, University of Bath, 1998. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284402.
Повний текст джерела
40
Richards, Stephen Paul. "Imidazolium salts as convenient precursors to novel metal-carbene complexes." Thesis, University of Bath, 2004. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.413916.
Повний текст джерела
41
Enderle, Bryan Anthony. "Bridging the gaps in catalysis : novel metal complexes as zeolite probes and metal cluster precursors /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2002. http://uclibs.org/PID/11984.
Повний текст джерела
42
Barstow, Sean J. "Use of photosensitive metal-organic precursors to deposit metal-oxides for thin-film capacitor applications." Diss., Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04082004-180015/unrestricted/barstow%5Fsean%5Fj%5F200312%5Fphd.pdf.
Повний текст джерела
43
Ezenwa, Emmanuel. "N,N-diethyl-N'-naphthoylacylchalcogourea to metal (II)complexes as precursors for ternary metal chalcogenide thin films via AACVD." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/nndiethylnnaphthoylacylchalcogoureatometal-iicomplexes-as-precursors-for-ternary-metal-chalcogenide-thin-films-via-aacvd(85420a4c-89d4-4465-9734-ca40a75ba924).html.
Повний текст джерелаАнотація:
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.
44
Redshaw, Carl. "Oxo and organoimido precursors for non-aqueous polytungstate synthesis." Thesis, University of Newcastle Upon Tyne, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328135.
Повний текст джерела
45
Pearce, Amber Marie. "Synthesis and characterisation of metal chalcogenide thin films." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/synthesis-and-characterisation-of-metal-chalcogenide-thin-films(7a22c662-639c-4aaf-a4cc-f2ae655115c0).html.
Повний текст джерелаАнотація:
There is much interest in the electronic potential of ‘nano’-semiconductors. The avenue of research pursued in this project was in inorganic analogues of graphene, namely metal chalcogenides MxEy (M = metal, E = S, Se, Te, x ≠ y = integer value). Thin films of these materials have been used in solar cells, ambient thermoelectric generators and IR detectors, due to their interesting properties, such as: optoelectronics, magnetooptic, piezoelectric, thermoelectric and photovoltaic, as well as electrical conductivity. The key issues with the use of these materials are the formation of controlled films, especially in terms of stoichiometry, crystallinity and uniformity, and also the precursor system used. The aim of this research was to synthesise and isolate novel precursor compounds for use in the deposition of metal sulfide thin films (for use with molybdenum and tungsten). The potential viability of the compounds as single source precursors (ssp) was judged following ThermoGravimetric Analysis (TGA). The compounds were also subjected to analysis using NMR (1H, 13C and 31P where applicable), infrared and UV-Vis spectroscopy, as well as elemental analysis. Cadmium sulfide (CdS) is one of the key direct band gap II-VI semiconductors, having vital optoelectronic applications for laser light-emitting diodes, and optical devices based on non-linear properties. The ratio of these films should ideally be 1:1, however, during the formation of cadmium sulfide films, particularly at elevated temperatures, a common problem encountered is the production of sulfur deficient films. These films have a formula consistent with 〖Cd〗_x S_y, where x is an integer value greater than y, but the sulfur deficiency is generally no greater than 10 %. In order to correct this sulfur deficiency, it was decided to investigate deposition making use of both a ssp and an additional sulfur source, with the aim of producing uniform films with 1:1 Cd:S.Molybdenum disulfide films have been deposited previously from multi source precursors and more recently using ssp. In this project MoS2 was deposited using novel ssps in both LP and AACVD on a variety of substrates with the aim of producing uniform thin films and assessing any differences in the morphology of the deposition. This work was continued with the deposition of WS2 and MoxW1-xS2 from ssps which had not been reported previously. The films deposited were analysed using XRD, SEM, EDX (when available) and Raman spectroscopy.
46
Venable, Margaret Hamm. "Syntheses, structures and support interactions of potential metal oxide catalyst precursors." Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/26940.
Повний текст джерела
47
Keeble, Andrew David. "Studies on metal alkoxides and carboxylates for use as catalyst precursors." Thesis, Durham University, 1990. http://etheses.dur.ac.uk/6181/.
Повний текст джерелаАнотація:
This thesis describes research carried out to investigate the feasibility of preparing high activity heterogeneous catalysts from the thermal decomposition of mixed metal alkoxides, carboxylates and hydroxycarboxylates, focusing in particular on the Cu/ZnO/Al(_2)0(_3) methanol synthesis catalyst. The rationale behind the project is discussed in the opening chapter of the thesis which is followed by literature reviews of heterogeneous catalysis and the chemistry of metal alkoxides, carboxylates and hydroxycarboxylates. Series of co-precipltation/crystallisation reactions of copper and zinc formates, oxalates and adipates were carried out as potential routes to double salts, Some such compounds were formed but in most cases mixtures of the individual salts resulted (xrd).Thermal decompositions of alkoxides and carboxylates of copper and zinc were investigated both as separate compounds and as mixtures. The nature of volatile species evolved (gas-phase ir) and of the solid residues (microanalysis, xrd) was different for the mixed decompositions compared to the individual ones, The conditions employed in decompositions of copper (II) formate with zinc methoxide (e.g. under vacuum or a stream of or N(_2) or N(_2)/H(_2)) affected the physical nature of the copper metal/zinc oxide residues, smallest particles resulting when using a N(_2) stream (transmission electron microscopy). Some of these materials showed activity for methanol synthesis. The reaction of soluble copper alkoxides (e.g. Cu(_I)0Bu) with anhydrous zinc 2-hydroxybenzoate, Zn(OzCCeH*(OH))^, led to the formation of apparently mixed metal compounds, for example CuZn(0(_2)CC(_6)H(_4)0)(_2)Py. The preparation of a new soluble alkoxy derivative of zinc is also reported: Li(_2)ZnCl(_2)(0CH(_2)CH(_2)(X:H(_2)CH(_2)0CH(_3))(_2).A summary of the results of the experimental work is given in relation to the project as a whole.
48
Rubiano, Rodrigo R. (Rubiano Ray). "Low temperature deposition of metal carbide films from single source precursors." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/34692.
Повний текст джерелаАнотація:
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1994, and Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Materials Science & Engineering, 1994.Includes bibliographical references (leaves 71-73).
by Rodrigo R. Rubiano.
B.S.
M.S.
49
Ashworth, Andrew Paul. "FTIR study of the thermolysis of some MOCVD precursors." Thesis, University of Nottingham, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315078.
Повний текст джерела
50
Mendoza-Espinosa, Daniel. "Synthesis and characterization of metallocalixarenes as precursors for the SOHIO model catalyst." [Fort Worth, Tex.] : Texas Christian University, 2009. http://etd.tcu.edu/etdfiles/available/etd-10162009-104543/unrestricted/Mendoza-Espinosa.pdf.
Повний текст джерела