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1
Charron, Luc G. "Radiative properties of molybdenum sulfide and other transition metal dichalcogenides." Thesis, University of Ottawa (Canada), 2004. http://hdl.handle.net/10393/26599.
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Low temperature radiative properties of the layered transition metal dichalcogenides 2H-MoS2, 2H-WS2 and 2H-WSe 2 are investigated. Synthetically grown crystals of all three materials, natural 2H-MoS2 single crystals and several 2H-MoS2 and 2H-WS2 commercial powders are studied. Steady-state photoluminescence (PL) measurements performed on the samples reveal two distinct radiative regions in the near infrared. The first region consisting of several sharp lines is produced by bound excitons related to the halogen transport agent intercalated within the van der Waals gap of the layered compounds. The second weaker region, composed of a broad spectral band, originates from the radiative recombination between an intrinsic crystal lattice defect center and the valence band in the conditions of a strong electron-phonon coupling. Time decay analysis of the bound excitonic radiative transitions is performed with time-resolved and PL intensity ratio measurements. The spectral and temperature dependence of the total radiative emissions of all three compounds are described in the framework of a two-channel kinetic recombination model in thermal equilibrium conditions. A configuration coordinate diagram is also constructed for 2H-MoS 2. PL intensity measurements performed on the 2H-MoS2 and 2H-WS2 synthetic crystals reveal a sublinear PL dependence on excitation intensity. Finally a technique developed to intercalate halogen molecules in natural 2H-MoS2 single crystals is described.
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Arancon, Rick Arneil. "Exploration of Transition Metal Sulfide Catalysts Prepared by Controlled Surface Chemistry." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEN063.
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L'hydrotraitement est un procédé catalytique important dans le raffinage du pétrole qui utilise des catalyseurs bimétalliques sulfurés NiWS ou NiMoS (ou CoMoS) supportés sur alumine. Leur mode conventionnel de préparation implique l’imprégnation d'une solution aqueuse de sels de Mo/W et de Ni/Co, puis l’activation par un agent sulfo-réducteur (H2S/H2). Pour répondre aux exigences environnementales et améliorer l'efficacité de l'hydrotraitement, des améliorations permanentes de la performance de ces systèmes catalytiques sont attendues. Ce travail se concentre sur la préparation de catalyseurs d'hydrotraitement hautement actifs par une approche de chimie de surface contrôlée (CSC) qui implique l'imprégnation successive de précurseurs moléculaires de MoV et NiII en solvant organique sur un support silice-alumine traité thermiquement. Dans la première partie de cette thèse, la genèse de la phase active du catalyseur CSC et conventionnel Mo et NiMo est étudiée par quick-XAS combinée à d’autres techniques (chimiométrie, XPS, RPE, STEM-HAADF, modélisation moléculaire). Nous proposons ainsi des structures moléculaires depuis les précurseurs oxydes de Mo et Ni supportés jusqu’aux nombreuses espèces intermédiaires (oxysulfure et sulfures) en fonction de la température. Cette analyse multi-technique permet d'abord de révéler les spécificités de la genèse des catalyseurs CSC et conventionnels qui peuvent expliquer leurs différentes activités catalytiques. Ensuite, elle révèle également de nouvelles connaissances sur les mécanismes d’insertion du Ni dans la phase NiMoS en fonction de la préparation. Dans la seconde partie, la possibilité de remplacer Co et Ni comme promoteurs est explorée. Ceci est entrepris en synthétisant des catalyseurs alternatifs de type XYMoS, où X et Y sont des métaux de transition 3d. Comme suggéré par des études de modélisation quantiques antérieures, certaines formulations XYMoS peuvent présenter un effet de synergie analogue à ceux des phases actives CoMoS et NiMoS. L’étude des formulations les plus prometteuses méritent d'être approfondies afin de mieux comprendre leur fonctionnement<br>Hydrotreating is an important catalytic process in petroleum refining which uses sulfided bimetallic catalysts NiWS or NiMoS (or CoMoS) supported on alumina. Their conventional preparation involves an incipient wetness impregnation of an aqueous solution of Mo/W and Ni/Co salts, and then activation by a sulfo-reductive agent (such as H2S/H2). To meet environmental regulations and improve the energy efficiency of hydrotreatment, permanent improvements on the performance of these catalytic systems are expected. This work is thus focused on the preparation of highly active hydrotreating catalysts through a controlled surface chemistry (CSC) approach; which involves the successive impregnation of Mo5+ and Ni2+ molecular precursors in an organic solvent on a thermally treated silica-alumina support. In the first part of this thesis, the active phase genesis of CSC and conventional Mo and NiMo catalysts is studied by in situ quick-XAS combined with various other techniques (chemometrics, XPS, EPR, STEM-HAADF, molecular modeling). We thus propose molecular structures from the oxide of supported Mo and Ni precursors up to the numerous intermediate sulfided species as a function of temperature. This multi-technique analysis enables first to reveal the specific features of the genesis of CSC and conventional catalysts which may explain their different catalytic activities. Then, it also reveals new insights into the mechanisms of Ni promoter incorporation into the NiMoS phase as a function of the preparation. In the second part, the feasibility of replacing Co and Ni as promoters is explored. Using the CSC method, we attempted to synthesize alternative catalysts of the form XYMoS ternary sulfides, where X and Y are 3d transition metals. As suggested by previous quantum simulations, certain XY formulations possibly reveal a synergy effect as observed in CoMoS and NiMoS active phases. The most promising formulations merit further investigations
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Kim, Changsu. "Optical, laser spectroscopic, and electrical characterization of transition metal doped ZnSe and ZnS nano- and microcrystals." Birmingham, Ala. : University of Alabama at Birmingham, 2009. https://www.mhsl.uab.edu/dt/2009r/kim.pdf.
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Thesis (Ph. D.)--University of Alabama at Birmingham, 2009.<br>Title from PDF title page (viewed Feb. 3, 2010). Additional advisors: Renato Camata, Derrick Dean, Chris M. Lawson, Andrei Stanishevsky, Sergey Vyazovkin. Includes bibliographical references (p. 133-140).
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Genisel, Mustafa Fatih. "Synthesis Of Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn Sulfides By Solid-gas Reactions, Investigation Of Structural And Conducting Properties." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/12606746/index.pdf.
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In this study some of the first row transition metal oxides were transformed to metal sulfides by new solid gas reaction system.
Transition metal sulfides have wide application area in industry and technology. Several techniques are known for the production of metal sulfides. Such as reactions between metal or metal oxide with H2S, precipitation in several liquid medium, reaction between metal and sulfur in closed vessel, chemical vapor deposition (CVD) technique. These techniques will have some disadvantages<br>for example, reactants are rarely available or expensive materials, their production systems are complicated and hard to set up these systems, products contain oxygen or hydrogen or corresponding metal sulfate as impurities.
In our new sulfidizing system the reactants are metal oxides, carbon and SO2. These materials can be found easily. Especially, SO2 usage in this system is a big advantage of giving possibility of usage the hazardous waste product of SO2 in industry.
The sulfidizing gas mixture was obtained by passing SO2 over activated carbon at 750 OC in a vertical tubular furnace. The obtained gas contains, mainly, CS2, CO and COS. The sulfidizing reactions took place in the horizontal tubular furnace at 450OC-1250 OC. The duration of the reaction, (three hours), and flow rate (60ml/min) of the SO2 gas were kept constant. The products were examined by X-ray powder diffraction and Raman scattering spectroscopy.
All examined metal oxides were transformed to metal sulfides by sulfidizing gas mixture successfully. Ti3S5 was obtained from TiO2. Cr2S3 was obtained from Cr2O3. MnS (Alabandite) was obtained from MnO2. FeS and Fe1-xS (Pyrrhotite) were obtained from Fe2O3. Co9S8 (Cobaltpentlandite) and CoS (Jaipurite) were obtained from Co3O4. NiS was obtained from NiO. Cu7.2S, Cu1.6S (Calcocite-Q), Cu1.81S, Cu7S4 (Anilite) Cu9S5 (Digenite), Cu8S5 (Geerite) were obtained from CuO, ZnS was obtained from ZnO.
The electrical conductivity character of each product obtained by sulfidizing reaction was analyzed in the temperature range of 77 K-300 K. Titanium sulfide, cobalt sulfide and nickel sulfide showed metallic conductivity, cupper sulfide and iron sulfide showed semiconductor behavior in this temperature range.
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Gao, Suning [Verfasser], Rudolf [Gutachter] Holze, Rudolf [Akademischer Betreuer] Holze, and Qunting [Gutachter] Qu. "Layered transition metal sulfide- based negative electrode materials for lithium and sodium ion batteries and their mechanistic studies / Suning Gao ; Gutachter: Rudolf Holze, Qunting Qu ; Betreuer: Rudolf Holze." Chemnitz : Technische Universität Chemnitz, 2020. http://d-nb.info/1219910309/34.
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Stephens, Ifan Erfyl Lester. "Polysulfide electrocatalysis at transition metal sulfides." Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608910.
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Yuan, Yanan. "Oxidative of organic compounds by oxysulfur radicals in the presence of transition metal ions and sulfite." Thesis, Université Clermont Auvergne (2017-2020), 2018. http://www.theses.fr/2018CLFAC052.
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Ces dernières années, de plus en plus de composés organiques réfractaires et toxiques ont été détectés dans les eaux usées. Un bon nombre de ces polluants organiques sont difficilement dégradés par des traitements classiques. Les procédés d’oxydation avancée à base de radicaux sulfates (SR-AOP) sont apparus comme une méthode innovante dans le domaine de la décontamination oxydative des eaux polluées. Des études antérieures ont porté sur ces SR-AOP utilisant du peroxodisulfate (PS) ou du peroxomonosulfate (PMS) comme oxydants, en particulier des couples «métaux de transition et oxydants» (systèmes Fe (II)/PS, systèmes Ni(II)/PMS et Co (II))/PMS), où il a été confirmé que SO4•-·présentent des avantages (sélectivité) par rapport au radical hydroxyle (HO•) pour la décontamination des eaux usées contenant des polluants organiques.Dans cette thèse, nous avons généré des radicaux tels que le radical sulfite SO3•-, le radical sulfate SO4•-, le radical peroxomonosulfate SO5•- à partir d’ions métalliques (Cr(VI), le Co(II), le Fe(III)) capables d’activer le sulfite pour la dégradation des composés organiques. L'efficacité d'élimination et le mécanisme d'oxydation ont été étudiés et le rôle des espèces soufrées a été élucidé<br>In recent years, more and more refractory and toxic organic compounds are detected in wastewater. Many of these organic pollutants can hardly be degraded by conventional water treatments. Sulfate radical based advanced oxidation process (SR-AOPs), have emerged as a promising method in the field of oxidative decontamination of polluted water. Past studies focused on this SR-AOPs with peroxydisulfate (PS) or peroxymonosulfate (PMS) as oxidants, especially the ‘transition metal + oxidants’ (i.e. Fe(II)/PS system, Ni(II)/PMS system and Co(II)/PMS system), which has been confirmed that SO4·− has advantages over HO in the decontamination of wastewater containing organic pollutants. In this PhD thesis, oxysulfur radicals including sulfite radical SO3·−, sulfate radical SO4·−, peroxymonosulfate radical SO5·− produced by transition metal ions such as Cr(VI), Co(II), Fe(III) activated sulfite were used to degrade organic compounds. The removal efficiency, the oxidation mechanism were examined, and and the role of sulfur species were elucidated
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Rees, David Alan. "Synthesis of alkaline earth transition metal sulfides." Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311775.
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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.
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Medoukali-Daamach, Sakina. "Contribution a l'etude des phenomenes cinetiques en extraction liquide-liquide : cas de l'extraction du palladium (ii) par les sulfures de dialkyle en milieu acide chlorhydrique." Paris 6, 1988. http://www.theses.fr/1988PA066629.
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Holmes, Kathryn E. "Structural diversity within transition metal-sulfimide complexes." Thesis, Loughborough University, 2003. https://dspace.lboro.ac.uk/2134/35645.
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S,S'-diphenylsulfimide, Ph2SNH, 1, is an excellent ligand that readily forms N-bound complexes with a range of transition metals. Its importance as a ligand is enhanced by two significant features of the resulting complexes: (1) the strong hydrogen bonding interactions between the NH unit and the counterions; and (2) the ligand's ability to stabilise unusual structural combinations. By varying the counterions, the hydrogen bonding pattern can be changed and this affects the geometry at the metal centre. The anion also plays an important role in determining the coordination number of the metal. The hydrogen bonding interactions have been utilised to prepare extended arrays by the inclusion of appropriate outer sphere, bridging ligands, such as terephthalate and fumarate into the system. The fixation of atmospheric CO2 has been observed in a number of systems leading to the formation of both a bicarbonate dimer and a metal-bound carbonate ligand. These act as hydrogen bonding acceptors to give extended 2-D networks.
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Eversfield, Sharon Gail. "An investigation of some disordered transition metal sulfides and cyanides." Thesis, University of Reading, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288770.
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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.
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Walton, Richard I. "The characterisation and structure of amorphous and poorly crystalline transition-metal chalcogenides." Thesis, University of Reading, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388467.
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Thompsen, Jeffrey Matthew. "High-resolution millimeter-wave spectroscopy of 3d-block transition-metal sulfides." Thesis, The University of Arizona, 2001. http://hdl.handle.net/10150/278773.
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The first pure-rotational spectra of two transition-metal sulfides, copper sulfide (CuS) and manganese sulfide (MnS) have been determined. In addition, the millimeter/sub-millimeter spectra of SrS, SrNH₂ and SrND₂ have been determined for the first time. Electronic ground states have been confirmed with experimental evidence. Results indicate that the bonding trends of the transition-metals sulfides are slightly different than their isovalent analogs, the transition-metal oxides. Furthermore, the study of MnS has allowed for experimental testing of current high spin-state quantum theory, by analysing the spectra using third and fourth-order corrections to the effective Hamiltonian. Highly accurate spectroscopic constants and rotational transition frequencies have been determined for all species.
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Crudden, Cathleen Marie. "Transition metal catalyzed carbonylations of vinylsilanes, allyl sulfides and related systems." Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/10882.
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It has been demonstrated that the zwitterionic rhodium complex (Rh zw), [Rh(COD)+]BPh4-, is an effective catalyst for the hydroformylation of vinylsilanes. With vinyltrimethylsilane, the branched aldehyde could be obtained as the major aldehyde isomer if the CO:H2 ratio was 1:2 (total pressure = 200 psi). Under these conditions, 20-40% isolated yield was obtained and the low Yield of these reactions was confirmed by experiments performed in deuterated solvents. The hydroformylation of vinyltriethylsilane, on the other hand, gave 66% of the desired aldehydes after 4h. The branched isomer was, however, the minor isomer with B:L selectivities of ca. 35:65. A cationic rhodium complex [Rh(COD)2+]BF 4-, abbreviated as (Rh+), was also found to catalyze the hydroformylation of vinylsilanes, but only in aromatic solvents. With the addition of 1 equivalent of triphenylphosphine, the reaction did proceed in non-aromatic solvents. The addition of PPh3 to the Rhzw catalyzed reactions dramatically improved the yield and selectivity for the linear isomer such that after the addition of only 2 equivalents, the products were formed in 97% yield with a B:L ratio of 7:93. This system is therefore much more sensitive to the effect of phosphines than the neutral complexes reported previously by Takeuchi et al.66 where the addition of 50--100 equivalents of phosphine was required in order to obtain >90% selectivity for the linear isomer. The unique solvent effects observed in the reactions of [Rh(COD) 2+]BF4- were explained by postulating that the aromatic solvent was acting as a ligand for the low-ligated rhodium complex. Furthermore, the activity of the zwitterionic complex in non-aromatic solvents was explained by co-ordination of one of the phenyl rings of the counterion. To gain support for this proposal, the stability of Rhzw under the reaction conditions was examined using high pressure and simple NMR techniques. These experiments led us to conclude that under severe conditions (140°C, 16h), 40% of the counterion is decomposed to benzaldehyde, benzyl alcohol and benzene. The mixture that resulted from this exhaustive treatment was shown to catalyze the hydroformylation of vinyltriethylsilane. However, when the rhodium complex was exposed to the conditions normally employed for carbonylation reactions, (namely 75°C, 3h, 200 psi), less than 15% decomposition to benzaldehyde was observed, and no benzene or benzyl alcohol could be detected. Finally, we prepared a number of arene-rhodium complexes and showed that they catalyzed the hydroformylation of vinyltriethylsilane in non-aromatic solvents. Chiral arene complexes were also prepared in order to test the enantioselectivity of the hydroformylation, but in these reactions, the branched isomer was completely isomerized to the enol silyl ether which did not permit assessment of the enantioselectivity. Other olefins were poor substrates. Styrene and vinyl naphthalene were polymerized under the reaction conditions, and olefin isomerization was problematic in the attempted hydroformylation of aliphatic substrates. The insertion of carbon monoxide into 6-membered ring heterocycles was examined using a variety of 1-alkyl-1,2,3,4-tetrahydroquinoline derivatives. It was found that under forcing conditions using Pd/Cu or Ru/Co complexes, up to 15% of products resulting from insertion of carbon monoxide could be observed. The isolation of these compounds and the determination of their structure was complicated due to the large amounts of metal salts employed, the decomposition of the remaining starting material and the low yields. MS data, however, confirmed that insertion of carbon monoxide had occurred. Finally, we examined the carbonylation of allyl aryl and allyl alkyl sulfides and found that the combination of Pd(OAc)2 and DPPP was effective only if a 1:1 ratio of metal:ligand was employed. Under these conditions, the alpha,beta-unsaturated thioester resulting from carbonylation and isomerization was formed in fair to good yields. Analysis of this compound by 1H NMR indicated that it was 100% trans. When Ru3(CO)12 was employed, the carbonylation could also be effected in lower yields after longer reaction times, and no isomerization of the product was observed. Thus the beta, gamma-unsaturated thioester was obtained from this reaction. The palladium catalyzed carbonylation was shown to proceed through a pi-allyl intermediate since 2-butenyl and 1-(3-butenyl) phenyl sulfide gave the same product. Furthermore, this experiment suggests that the rate determining step was carbonylation and not oxidative addition.
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Zhang, Yuan. "Prepartion of multi-metal sulfides for electrochemical supercapacitors." Thesis, Lille 1, 2020. http://www.theses.fr/2020LIL1I014.
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Ces dernières années, les supercondensateurs électrochimiques (SE), en tant que systèmes de stockage d'énergie respectueux de l'environnement, sont confrontés à plusieurs défis liés aux performances, à la fonctionnalité et à la durabilité des matériaux clés. Parmi les différents types de supercondensateurs électrochimiques, les supercondensateurs hybrides combinent des électrodes avec différents mécanismes de stockage. En particulier, la combinaison d’électrodes à double couche (EDLC) et de type batterie devrait offrir une performance électrochimique améliorée. En ce qui concerne les supercondensateurs hybrides à comportement EDLC // type batterie, il a été largement reconnu que les matériaux en carbone, en raison de leur excellente conductivité électrique, de leur stabilité électrochimique et de leur grande surface spécifique, sont les candidats les plus prometteurs pour les matériaux d'électrode avec un comportement de type EDLC. En ce qui concerne les matériaux d'électrodes ayant un comportement de type batterie, il a été prouvé qu'en raison des réactions de transfert de charge faradiques impliquées dans le processus électrochimique, les matériaux à base de métaux de transition ont la capacité de stocker beaucoup de l'énergie et sont des candidats prometteurs pour les matériaux d'électrodes avec un comportement de type batterie. Dans cette thèse, différents matériaux d'électrodes en carbone, tels que l'oxyde de graphène réduit (rGO), l'oxyde de graphène réduit poreux (PrGO) et le polyéthylène-dioxythiophène-Fe-900 (PF-9), ont été préparés par une méthode d'oxydation et de réduction chimiques. De plus, des matériaux d'électrodes composés de métaux de transition, tels que CoS / support carboné (rGO ou PF-9), ZnCoS, ZnS / Ni3S2 et Sb2S3 / CoS2 / CrOOH ont été synthétisés par co-précipitation chimique et méthode d'échange d'ions. Une variété de techniques différentes (MES, MET, DRX, XPS, ICP-AES, BET, Raman) ont été utilisées pour caractériser les propriétés physico-chimiques des matériaux d'électrodes ainsi préparés. Leur performance électrochimique est également évaluée dans une cellule à 3 électrodes. Enfin, des supercondensateurs hybrides ont été assemblés et leur performance électrochimique a été évaluée dans un système à deux électrodes<br>In recent years, electrochemical supercapacitors (ESs), as environmentally-friendly energy storage systems, are facing several challenges associated with the performance, functionality, and durability of key materials. Among different types of ESs, hybrid supercapacitors, the combination of electrodes with different energy storage mechanisms, especially the combination of electrochemical double layer capacitance (EDLC) and battery-type behavior, are expected to offer enhanced electrochemical performance. Concerning hybrid supercapacitors consisting of EDLC//battery-type electrode materials, carbonaceous materials, owing to their excellent electrical conductivity, electrochemical stability, and large specific surface area, are the most promising candidates for electrode materials with EDLC-type behavior. For electrode materials with battery-type behavior, owing to the faradaic charge transfer reactions involved in the electrochemical process, transition metal compounds can store plenty of energy and represent one of the most promising candidates for electrode materials with battery-type behavior. In this thesis, different carbonaceous materials, such as reduced graphene oxide (rGO), porous reduced graphene oxide (PrGO), and poly-ethylene dioxythiophene-Fe-900 (PF-9), are prepared through chemical oxidation and reduction methods. Moreover, transition metal compounds, such as CoS/carbonaceous support (rGO or PF-9), ZnCoS, ZnS/Ni3S2 and Sb2S3/CoS2/CrOOH, are synthesized via chemical co-precipitation and ion-exchange method. A variety of different techniques, including XPS, SEM, ICP-AES, TEM, XRD, BET, and Raman, are used to investigate the physicochemical performance of as-prepared materials. Their corresponding electrochemical performance is also evaluated through a 3- electrode system. Additionally, hybrid supercapacitors consisting of as-prepared carbon and transition metal electrodes are assembled, respectively, and their electrochemical performance is evaluated through the 2- electrode system
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MUDARMAH, KHALIL. "REACTIVITY OF MOLYBDENUM AND TUNGSTEN SULFIDO COMPLEXESWITH FIRST-SERIES TRANSITION METALS." Cleveland State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=csu1566563467202265.
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Jiang, Nan. "First-Row Transition Metal Sulfides and Phosphides as Competent Electrocatalysts for Water Splitting." DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/6480.
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Conversion of renewable energy resources (such as solar and wind) through water splitting to hydrogen and oxygen has attracted increasing attention. The sole product of hydrogen combustion is water, rendering a carbon-neutral energy cycle. Water splitting consists of two redox half reactions: hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Both of these two transformations involve multi- electron/proton movement and thus are kinetically sluggish. In order to accelerate the reaction rates for practical application, efficient catalysts are needed. State-of-the-art catalysts for water splitting are usually composed of noble metals, such as platinum, ruthenium, and iridium, whose scarcity and high cost limit their wide employment. Consequently, it is of critical importance to develop competent and non-precious catalysts via low-cost preparation.
Owing to the thermodynamic convenience and potential application in proton exchange membrane and alkaline electrolyzers, traditionally, most HER catalysts were developed under strongly acidic conditions while OER catalysts under strongly alkaline conditions. In order to accomplish overall water splitting, the coupling of HER and OER catalysts in the same electrolyte is mandatory. This thesis will summarize our recent efforts towards developing 1st-row transition metal-based sulfides and phosphides for electrocatalytic water splitting under ambient conditions.
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Maheu, Clément. "Study of Titania supported transition metal sulfides for the photocatalytic production of hydrogen." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1172.
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La photocatalyse est une voie de synthèse prometteuse de l’hydrogène comme carburant solaire. La production photocatalytique est un moyen, à la fois de stocker l’énergie solaire sous forme d’énergie chimique et de produire des carburants de manière renouvelables en utilisant l’eau ou des alcools biosourcés comme matière première. L’objectif de cette thèse est d’étudier la déshydrogénation photocatalytique d’alcools à l’aide de sulfures de métaux de transitions, supportés sur TiO2 (MSx/TiO2). Ces sulfures de métaux de transitions ont des propriétés d’activation de l’hydrogène, des propriétés électrochimiques et des propriétés optiques intéressantes. Une série de sept MSx/TiO2 (M = Co, Ni, Cu, Mo, Ru, Ag, Hg) ont été étudiés. La réaction de déshydrogénation photocatalytique du propan-2-ol est utilisée comme réaction modèle. Des corrélations sont établies entre les propriétés intrinsèques de ces MSx/TiO2 et leur activité photocatalytique. De plus, la mesure d’énergie d’activation d’apparente apporte une compréhension supplémentaire sur les mécanismes photocatalytiques. Cette dernière montre que la production photocatalytique d’hydrogène est principalement limitée par les phénomènes de séparation et de transfert de charges dans les photocatalyseurs. Ainsi, une méthodologie combinant la spectroscopie de photoélectrons UV et la spectroscopie d’absorption UV-Visbile a été mis en place pour déterminer la structure électronique des poudre photocatalytiques. Ce travail conclue sur le caractère central de la structure électronique en photocatalyse. Dans le cas du photocatalyseur RuS2/TiO2, le transfert électronique est l’étape cinétiquement déterminante pour la déshydrogénation photocatalytique du propan-2-ol<br>Photocatalysis is a promising way to synthesize H2 as a solar fuel. On one hand, the photocatalytic H2 production stores solar energy under chemical energy. On the other hand, it produces H2 with a renewable process using water and bio-based alcohols as a feedstock. This Ph.D thesis aims to study the photocatalytic dehydrogenation of alcohols with transition metal sulfides supported on TiO2 (MSx/TiO2). Those transition metal sulfides have versatile and highly tunable properties. They can activate H2, they have promising electrochemical behavior and optical properties. Seven MSx/TiO2 (M = Co, Ni, Cu, Mo, Ru, Ag, Hg) are therefore studied. The photocatalytic dehydrogenation of propan-2-ol is used as a model reaction. Structure-activity relationships are found between the intrinsic properties of the MSx/TiO2 and their photocatalytic activity. Measuring an apparent activation energy provides additional mechanistic insights. It shows that the photocatalytic production of hydrogen is mostly limited by the charge carrier separation and by the electronic transfer. Therefore a method combining the UPS and the UV-Visbile absorption spectroscopies has been develop to establish the electronic structure of photocatalytic powders. This work concludes that the electronic structure plays a crucial role in photocatalysis. With RuS2/TiO2 photocatalyst, the electron transfer is evidenced as the rate-determining step of the photocatalytic dehydrogenation of propan-2-ol
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Zhou, Xiuquan. "Non-hydrolytic Sol-gel (NHSG) Synthesis of Transition Metal Sulfides and Theoretical Investigations." University of Toledo / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1365030696.
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Coleman, Nathaniel Jr. "Synthesis and characterization of metal doped titanium dioxide, transition metal phosphides, sulfides and thiophosphates for photocatalysis and energy applications." Diss., University of Iowa, 2015. https://ir.uiowa.edu/etd/2060.
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This thesis covers synthetic investigations, characterization, and applications of transition metal doped titanium dioxide materials and transition metal phosphide/sulfide structures. Both areas are useful in heterogeneous catalysis, battery energy storage, and in semiconductor light to energy conversion. Two main synthesis routes have been investigated: 1) rapid solid state metathesis (SSM) of transition metal oxides, phosphides, sulfides, and thiophosphates, and 2) sealed ampoule routes of transition metal phosphides and thiophosphates. SSM reactions tend to yield kinetically controlled multiphase products while sealed ampoule routes gave more thermodynamically favorable single phase materials.
Approximately 10 mol% of many first row transition metals (M = Cr, Mn, Fe, Co, Ni, Cu) were targeted for doping into TiO₂, using MClx, and sodium peroxide in SSM reactions, targeting an ideal mixed phase of M₀.₁Ti₀.₉O₂. X-ray diffraction showed rutile TiO₂ forms and no separate dopant metal phases were seen until subsequent 1000 °C annealing in air. EDS, ICP, and XPS analysis showed slightly lower than the targeted M:Ti ratios however, the manganese sample had more than the ideal 10 mol % of dopant. DRS data showed estimated bandgap energies of the doped samples within 1.33-2.55 eV. Magnetic susceptibility showed small paramagnetic responses from all samples that increase upon annealing. SEM showed that the doped SSM-TiO₂ samples were mixtures of aggregates and blocky particles.
The synthesized doped titanias were tested for methylene blue and methyl orange photodegradation under UV and visible light and for H₂ generation from water reduction under UV light. The doped titania samples absorb significant amounts of methylene blue dye in the dark with the manganese doped TiO₂ sample being the most absorbent. Degradation of methylene blue under UV illumination was observed, however, only modest degradation under visible light was observed. The samples all performed better than Degussa P25 TiO₂ standard under visible light. The doped titanias did not degrade methyl orange well under UV light and they did not show detectable H₂ generation from water in UV light even with surface platinum additions.
Transition metal phosphide, sulfide and thiophosphate materials were synthesized in two different ways. The metal halides FeCl₃, CoCl₂, NiCl₂, and CuCl₂, red phosphorus and elemental sulfur (or P₂S₅) were common to both SSM and ampoule reactions. Both SSM reactions and sealed glass ampoules are solvent-less direct solid state reactions to target FeP₂, CoP₃, NiP₂, CuP₂, FeS₂, CoS₂, NiS₂, CuS, FePS₃, CoPS₃, NiPS₃ and Cu₃PS₄ phases. SSM reactions utilized MClx/Li₃N mixtures to produce elemental metals to then react with P/S reagents leading to metal-rich phosphides, sulfur-rich phases or mixes of M-P-S and sulfur rich phases. Phosphorus-rich phases were seldom seen. Ampoule reactions in contrast, produced single phase phosphorus-rich phases and M-P-S products. Sulfide phases were not produced in ampoule systems.
To encourage unique product morphologies, the metal phosphide and thiophosphates were directly synthesized on P25 TiO₂ powders, and pre-made molten fluxes (KCl/LiCl eutectic, tin, or bismuth) to encourage crystal growth of unique structures. M-P products were successfully synthesized in the eutectic and tin fluxes, except for FeP₂ in the halide eutectic flux. FeP₂ was grown in the tin flux at lower than normal reaction temperatures (500 °C vs 700 °C). M-P-S products were seen in the eutectic flux only, while SnS, M-P, or M –Sn-P products were observed in tin fluxes. All reactions were unsuccessful in bismuth flux. The deposition reactions yielded M-P and M-P-S products on P25 TiO₂ powder. The NiP₂ and CuP₂ products were seen while FeP₂ and CoP₃ were not observed. From these samples, only FeP and CoP was detected on P25 TiO₂. The M-P-S reactions formed the targeted phases on P25 TiO₂ successfully. These deposited materials were tested for their photo-reactivity towards water reduction.
Preliminary tests for UV light induced and electrolytic hydrogen evolution were done using some ampoule synthesized M-P and M-P-S materials. None of the samples showed H₂ generation using UV light, however H₂ was detected from several MPx and MPxSy materials in this thesis under acidic electrochemical conditions at fairly low applied overpotentials of -40 mV to -240 mV.
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Verna, Frédérique. "Etude de l'interaction metal-compose sulfure en catalyse d'hydrogenation." Paris 6, 1988. http://www.theses.fr/1988PA066584.
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Dans la premiere partie de ce travail, l'adsorption de divers composes sulfures sur des catalyseurs palladium sur alumine a ete etudiee dans les conditions de l'hydrogenation en phase liquide et a une temperature inferieure a 100**(o)c. Dans une deuxieme partie, l'etude s'est portee sur l'influence du taux de couverture en soufre sur les proprietes catalytiques de pd/al::(2)o::(3) dans diverses reactions. Hydrogenation du butene-1, du butadiene-1,3, du butyne-1, ainsi que l'isomerisation du butene-1 en butene-2
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Araujo, Santos Ana. "Development of a novel integrated system for bioremediating and recovering transition metals from acid mine drainage." Thesis, Bangor University, 2018. https://research.bangor.ac.uk/portal/en/theses/development-of-a-novel-integrated-system-for-bioremediating-and-recovering-transition-metals-from-acid-mine-drainage(9587ab26-7e31-4728-8206-29850860ccfa).html.
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Mine-impacted water bodies are considered to be one of the most serious threats to the environment. These can be highly acidic and often contain elevated concentrations of sulfate and soluble metals. The microbial generation of H2S by reduction of more oxidized sulfur species, and consequent precipitation of metal sulfides, known as biosulfidogenesis, is a promising technology for remediating acid mine drainage (AMD). The objective of this work was to develop an integrated system for remediating a target AMD at an operating mine in northern Brazil using a single low pH anaerobic sulfidogenic bioreactor (aSRBR) and an aerobic manganese-oxidizing bioreactor. A synthetic version of the mine water, which contained 7.5 mM copper and lower concentrations (< 0.25 mM) of other transition metals (Zn, Ni, Co and Mn) was used in the experimental work. In the first stage, H2S generated in the aSRBR was delivered to an off-line vessel containing synthetic AMD, which removed > 99% copper (as CuS) while no co-precipitation of other metals was apparent. The partly-processed AMD was then dosed with glycerol and fed into the aSRBR where zinc, nickel and cobalt were precipitated. The effect of varying the pH and temperature of the bioreactor was examined, and > 99% of Ni, Zn and Co were precipitated in the aSRBR when it was maintained at pH 5.0 and 35ºC. The bacterial communities, which were included 4 species of acidophilic sulfate-reducing bacteria, varied in composition depending on how the bioreactor was operated, but were both robust and adaptable, and changes in temperature or pH had only short-term impact on its performance. Manganese was subsequently removed from the partly-remediated synthetic AMD using upflow bioreactors packed with Mn(IV)-coated pebbles from a freshwater stream which contained Mn(II)-oxidizers, such as the bacterium Leptothrix discosphora and a fungal isolate belonging to the order Pleosporales. This caused soluble Mn (II) to be oxidised to Mn (IV) and the precipitation of solid-phase Mn (IV) oxides. Under optimised conditions, over 99% manganese in the processed AMD was removed. Metal sulfides (ZnS, CoS and NiS) that had accumulated in the aSRBR over 2 years of operation were solubilised by oxidative (bio)leaching at low pH. With this, ~ 99% Zn, ~ 98% Ni and ~ 92% Co were re-solubilised, generating a concentrated lixiviant from which metals could be selectively recovered in further downstream processes. The use of methanol and ethanol either alone or in combination with glycerol were evaluated as alternative electron donors for biosulfidogenesis. Methanol was not consumed in the bioreactor, though sulfate reduction was not inhibited in the presence of up to 12 mM methanol. In contrast, ethanol was readily metabolised by the bacterial community and sulfate reduction rates were relatively high compared to glycerol. Two acidophilic algae were characterised and their potential to act as providers of electron donors for biosulfidogenesis was also evaluated. Although algal biomass was able to fuel sulfate reduction in pure cultures of aSRB and in the aSRBR, rates were much lower than when either glycerol or ethanol were used.
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Sundberg, Jill. "Triboactive Low-Friction Coatings Based on Sulfides and Carbides." Doctoral thesis, Uppsala universitet, Oorganisk kemi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-230989.
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For sustainable development, it is highly important to limit the loss of energy and materials in machines used for transportation, manufacturing, and other purposes. Large improvements can be achieved by reducing friction and wear in machine elements, for example by the application of coatings. This work is focused on triboactive coatings, for which the outermost layer changes in tribological contacts to form so-called tribofilms. The coatings are deposited by magnetron sputtering (a physical vapor deposition method) and thoroughly chemically and structurally characterized, often theoretically modelled, and tribologically evaluated, to study the connection between the composition, structure and tribological performance of the coatings. Tungsten disulfide, WS2, is a layered material with the possibility of ultra-low friction. This work presents a number of nanocomposite or amorphous coatings based on WS2, which combine the low friction with improved mechanical properties. Addition of N can give amorphous coatings consisting of a network of W, S and N with N2 molecules in nanometer-sized pockets, or lead to the formation of a metastable cubic tungsten nitride. Co-deposition with C can also give amorphous coatings, or nanocomposites with WSx grains in an amorphous C-based matrix. Further increase in coating hardness is achieved by adding both C and Ti, forming titanium carbide. All the WS2-based materials can provide very low friction (down to µ<0.02) by the formation of WS2 tribofilms, but the performance is dependent on the atmosphere as O2 and H2O can be detrimental to the tribofilm functionality. Another possibility is to form low-friction tribofilms by tribochemical reactions between the two surfaces in contact. Addition of S to TiC/a-C nanocomposite coatings leads to the formation of a metastable S-doped carbide phase, TiCxSy, from which S can be released. This enables the formation of low-friction WS2 tribofilms when a Ti-C-S coating is run against a W counter-surface. Reduced friction, at a moderate level, also occurs for steel counter-surfaces, likely due to formation of beneficial iron sulfide tribofilms. The studied coatings, whether based on WS2 or TiC, are thus triboactive, with the ability to form low-friction tribofilms in a sliding contact.
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Melzig, Laurin. "Sulfoxide-Controlled Functionalization of Arenes and Heterocycles Transition Metal-Catalyzed Cross-Coupling Reactions of Thioethers Chlorine-Zinc Exchange Reactions." Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-129202.
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Lemoine, Pascale. "Combinaisons ternaires soufrées formées par l'europium et un second métal : exemples de dérivés de l'europium à valence mixte; synthèse, structures et propriétés physiques." Paris 6, 1986. http://www.theses.fr/1986PA066416.
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L'études des combinaisons ternaires soufrées formées par l'europium et un second métal conduit dans de nombreux cas a des composes qui ne contiennent que de l'europium divalent, tels que Eu3Sb4S9, EuLn2S4 (Ln: Dy—Lu, Y) et Eu1,1Bi2S4. . Dans ces trois composes Eu (ii) présente un environnement 8-prismatique et le second métal, un environnement octaédrique. Dans Eu3Sb4S9, le doublet 5s2 non-engagé de Sb (iii) crée de larges tunnels au sein de la structure. Les composés EuLn2S4 ont une structure de type CaFe2O4. Le réseau du composé Eu1, 1Bi2S4 contient de larges canaux partiellement occupés par des atomes d'europium divalent d'environnement 9-prismatique. Dans quelques cas, lorsque le second métal est susceptible de stabiliser partiellement la valence iii de l'europium, des composés à valence mixte sont obtenus, tels Eu2BiS4 et Eu2CuS3 qui contiennent les deux valences de l'europium, mais de façon différenciée par des sites cristallographiques distincts. Dans Eu2BiS4, Eu(ii) a un environnement 7-prismatique, Eu (iii), 7-octaedrique et Bi (iii), octaédrique. Dans Eu2CuS3, Eu (ii) a un environnement 8-prismatique, Eu(iii), octaédrique et Cu (i),tétraédrique. Dans ces deux composés, il existe des feuillets perpendiculaires à l'axe b, de formule Eurs(3) (r = Cu ou Bi). Tous ces composés sont paramagnétiques et semi-conducteurs. Cette étude met en évidence la stabilité de l'état divalent de l'europium dans les sulfures et la nécessité pour obtenir des composes à valeur mixte ou intermédiaire de l'europium, de modifier les conditions d'études, telles que la température et la pression.
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Wagenhofer, Manuel Florian [Verfasser], Johannes A. [Akademischer Betreuer] Lercher, Johannes A. [Gutachter] Lercher, Klaus [Gutachter] Köhler, and Roel [Gutachter] Prins. "Unsupported transition metal sulfides for hydrotreating of conventional and renewable feedstock / Manuel Florian Wagenhofer ; Gutachter: Johannes A. Lercher, Klaus Köhler, Roel Prins ; Betreuer: Johannes A. Lercher." München : Universitätsbibliothek der TU München, 2020. http://d-nb.info/1220423718/34.
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Adigun, Risikat Ajibola. "Insight into the Reactivity of Metastasis Inhibitor, Imidazolium trans-[tetrachloro (dimethyl sulfoxide)(imidazole)ruthenate(III)], with Biologically-active Thiols." PDXScholar, 2012. https://pdxscholar.library.pdx.edu/open_access_etds/378.
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Imidazolium trans-[tetrachloro (dimethyl sulfoxide)(imidazole)ruthenate(III)], NAMI-A, is an experimental metastasis inhibitor whose specific mechanism of activation and action remains to be elucidated. In the nucleophilic and reducing physiological environment; it is anticipated that the most relevant and available reductants upon introduction of NAMI-A as a therapeutic agent will be the biologically-relevant free thiols. The kinetics and mechanisms of interaction of NAMI-A with biologically-active thiols cysteamine, glutathione, cysteine and a popular chemoprotectant, 2-mercaptoethane sulfonate (MESNA) have been studied spectrophotometrically under physiologically-relevant conditions. The reactions are characterized by initial reduction of NAMI-A with simultaneous formation of dimeric thiol and subsequent ligand exchange with water to various degrees as evidenced by Electospray Ionization Mass Spectrometry. Stoichiometry of reactions shows that one molecule of NAMI-A reacted with one mole of thiol to form corresponding disulfide cystamine, dimeric MESNA, oxidized glutathione and cystine. Observed rate constants, ko, for the reaction of NAMI-A with cysteamine, MESNA, GSH and cysteine were deduced to be 6.85 + 0.3 x 10-1, 9.4 + 0.5 x 10-2 , 7.42 + 0.4 x 10-3 and 3.63 + 0.3 x 10-2 s-1 respectively. Activation parameters determined from Arrhenius plots are indicative of formation of associative intermediates prior to formation of products. A negative correlation was obtained from the Brønsted plot derived from observed rate constants and the pKa of the different thiols demonstrating significant contribution of thiolate species towards the rate. In conclusion, interactions of NAMI-A with biologically-active thiols are kinetically and thermodynamically favored and should play significant roles in in vivo metabolism of NAMI-A.
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Matussek, Julia. "Syntheses and Characterization of Polyimidosulfate Complexes." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2014. http://hdl.handle.net/11858/00-1735-0000-0022-5DB9-8.
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Abdi, Djamila. "Application de l'electrode a disque tournant a l'etude du comportement electrochimique du cuivre en milieu neutre et en milieu acide en absence et en presence d'especes sulfurees." Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13176.
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Etude de la corrosion du cuivre en milieu acide (perchlorique acide) et saline (borate de sodium) par des techniques electrochimiques. Influence des especes sulfures sur la cinetique de corrosion des electrodes tournantes en cuivre
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Ben, Salem Azzedine. "Synthese et caracterisation physique et structurale des conducteurs unidimensionnels de type fe : :(1+x)nb::(3-x)se::(10)." Nantes, 1987. http://www.theses.fr/1987NANT2018.
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Ce compose est le prototype d'une serie de formulation (mm')nb::(2)s::(10)(mm' = fe,v,cr,nb,ta) presentant une chaine trigonale prismatique |nbse::(3)| et une double chaine oelaedrique |(mm')se::(6)|. Ces composes ont une transition metal isolant vers 140 k. L'observation d'une onde de densite de charge aux caracteristiques identiques a celles de nbse::(3) indique que la chaine conductrice est la chaine trigonale prismatique |nbse::(3)|. La variation de la conductivite au voisinage de la transition indique un mecanisme de localisation d'anderson. Les proprietes physiques du compose ou se a ete substitue par s ont ete etudiees. L'etude de l'insertion par li a ete effectuee
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Fraccaroli, Mathias. "Synthèse par CVD/ALD sur grandes surfaces d'un sulfure de vanadium transparent et conducteur." Thesis, Université Grenoble Alpes, 2020. http://www.theses.fr/2020GRALT006.
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Dans un contexte de diversification des fonctionnalités sur silicium (more than Moore), les sulfures de transition sont actuellement activement étudiés pour la réalisation de dispositifs optiques originaux. Dans cette famille, certains matériaux présentent une structure lamellaire structurellement semblables au graphène. C'est le cas de certains sulfures de vanadium. La synthèse de ces films lamellaires reste activement dominée par les procédés CVD à haute température (>550°C). Cependant, pour espérer le développement d'une synthèse fiable, il est important de diminuer cette température de dépôt qui conduit à des films souvent peu uniforme et conforme. Dans ce travail nous avons étudié la potentialité d'une approche de dépôt par voie chimique en phase vapeur à basse température (200°C). Cette synthèse a permis l'obtention d'un film de sulfure de vanadium amorphe sur un substrat de 300mm et a montré la capacité de ce film à se réorganiser pour obtenir un film lamellaire de V7S8 après recuit thermique. Un film de 5,2nm présente des propriétés optiques et électriques intéressantes ; ce film est conducteur il possède une densité de porteur de 1,1.1023 cm-3, les porteurs majoritaires sont les trous (type p), une mobilité de 0,2 cm2.(V.s) -1, une conductivité de 1063 S.cm-1, un travail de sortie de 4,8 eV tout en préservant une bonne transparence (transmittance de 75% pour une longueur d’onde de 550nm)<br>In the context of functional diversification (“More than Moore”), transition sulfides are currently being actively studied for original optical devices production. Some materials in this family have a lamellar structure, similar to graphene like vanadium sulfides. The synthesis of these lamellar films remains actively dominated by high-temperature CVD processes (> 550 ° C). However, in order to hope the development of a reliable synthesis methods, it's important to reduce this deposition temperature which leads to a poor uniformity and a poor conformity. In this work we have studied the potential of a chemical vapor deposition approach at low temperature (200 ° C). This method allow us to obtain an amorphous vanadium sulfide film on a 300 mm wafer and point out theirability to self-reorganize in order to obtain a lamellar film of V7S8 after thermal annealing. A 5.2nm film has interesting optical and electrical properties; this film is conductive with a carrier density of 1.1.1023 cm-3, the holes are the main charges carriers (type p), a mobility of 0.2 cm2. (Vs) -1, a conductivity of 1063 S.cm -1, an output work of 4.8 eV while preserving good transparency (transmittance of 75% for a wavelength of 550nm)
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Li, Zhigang. "Formation et simulation de l'image en microscopie electronique a haute resolution : application a la structure de composes de type "lamellaire"." Toulouse 3, 1987. http://www.theses.fr/1987TOU30282.
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Cette these etudie trois problemes specifiques de la microscopie electronique a haute resolution : le transfert du contraste des images, leur interpretation au moyen de simulations et l'application de cette technique a la determination des structures locales dans les materiaux cristallins, au niveau atomique. Obtention de resultats originaux en ce qui concerne la microstructure de materiaux de type lamelllaire : dans les composes de type re::(6) se::(8) cl::(2), avant et apres insertion d'hydrazine, dans les composes de type mps::(3) et dans taps::(6)se
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Dinia, Mohammed Aziz. "Etude des propriétés magnétiques et supraconductrices des composés : HoMo6S8, EuMo6S8 et CeMo6S8." Grenoble 1, 1987. http://www.theses.fr/1987GRE10072.
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Etude par des mesures magnetiques et electriques et par diffraction de neutrons, portant principalement sur la coexistence de la supraconductivite et du magnetisme dans homo::(6)s::(8). Cette coexistence est observee non seulement pour la structure magnetique modulee, mais aussi dans le cas d'une structure antiphase, la disparition de la supraconductivite etant liee au developpement des moments magnetiques des ions ho**(3+). Diagramme de phases; role des interactions electromagnetiques (interactions dipolaires, champ demagnetisant). Etat fondamental des ions lanthanide; role de l'effet kondo dans le cas de cemo::(6)s::(8)
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GERARD, BRUNO. "Luminescence retardee stimulee electriquement dans les sulfures de zinc et de cadmium actives au cuivre, a l'or ou a l'argent et coactives a l'aluminium : application a un imageur mammographique numerique a memoire." Paris 6, 1988. http://www.theses.fr/1988PA066252.
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Etude de la faisabilite de cet imageur utilisant, comme principe d'acquisition de l'image x, l'effet gudden-pohl, phenomene de luminescence retarde stimulee electriquement (lse). Seuls zns et cds dopes par cu, au ou ag donne l'effet lse adequat apres une phase de sensibilisation. Variation de la luminescence en fonction de la dose de rayons x, du champ electrique, de la temperature, du dopage, etc. Modelisation de l'effet lse: l'enregistrement de l'image se fait par piegeage de trous sur des accepteurs dans la couche d'appauvrissement superficielle, la recombinaison radiative se produisant avec ces trous lorsque le champ electrique applique abaisse la barriere de potentiel superficielle. Elaboration d'une maquette en vue du developpement d'un imageur mammographique numerique
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Catherin, Nelly. "Selective ring opening of naphthenes over bifunctional catalysts in the presence of H2S." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1246.
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L'ouverture sélective de cycle (OSC) d'hydrocarbures polycycliques vise à augmenter le nombre de cétane des carburants diesel. OSC efficace peut être atteint par l'hydroconversion sur des catalyseurs bifonctionnels métal noble/fonction acide. La décaline et, à plus faible mesure, le perhydroindane, le butylcyclohexane et la tétraline, ont été utilisés comme molécules modèles pour l'étude des l'OSC de sulfures de métaux de transition (TMSs) supportés sur zéolithes ou silice-alumine amorphe dans un réacteur à lit fixe sous haute pression (5 MPa) avec une concentration élevée d'H2S dans la charge réactionnelle (1 %). Les nombreux produits d'hydroconversion ont été identifiés grâce à la chromatographie gazeuse bidimensionnelle, qui nous a permis de mieux comprendre les mécanismes de réaction. Ce travail a consisté à l'étude de la nature et la charge du SMT et la nature du support. Comparé à la zéolithe seule, le catalyseur RuSx/HY (qui sert de référence) est plus stable et dix fois plus actif avec une sélectivité en produits d'ouverture proche des 30% à 240 °C. Les produits les plus abondants restent les produits d'isomérisation, ce qui suggère que l'acidité du support domine le schéma réactionnel. Quant à l'ajout de TMS, leur rôle est d'activer l'hydrogène, de favoriser les réactions d'hydrogénation/déshydrogénation et limiter le cokage des sites acides. NiSx/HY est aussi performant que les catalyseurs à base de Ru, Ir ou Rh et un effet de synergie est observé pour les catalyseurs ternaires Ni-Ru et Ni-Rh. Toutefois, comparé aux métaux nobles comme l'Ir et le Ru étudiés sans H2S, les catalyseurs sulfures sont quasiment non-hydrogénolysants. Enfin, la zéolithe HY présente des performances proches a la H-Beta mais avec moins de craquage<br>The selective ring opening (SRO) of polycyclic hydrocarbons aims at increasing the cetane numbers of diesel fuels. Efficient SRO can be achieved through hydroconversion over bifunctional noble metal/acid catalysts. Decalin and, to lower extents, perhydroindan, butylcyclohexane and tetralin, have been used as model molecules to investigate the SRO performances of transition metal sulfides (TMSs) supported on zeolites or amorphous silica-alumina in a high-pressure (5 MPa) flow-fixed bed reactor with a high concentration of H2S in the reactant feed (1 %). The numerous hydroconversion products have been identified using comprehensive two-dimensional chromatography for various levels of reactant conversions, which allowed us to gain insight into the reaction mechanisms. The presence, loading and nature of the TMS, and the nature of the support, have been investigated. With respect to the bare HY zeolite, RuSx/HY (which served as our reference) is more stable and ten times more active, with a ring-opening selectivity of up to 30 % at 240 °C. The most abundant products are skeletal-isomerization ones, which suggests that the acidic support dominates the reaction scheme. The TMS role is to activate hydrogen, catalyze hydrogenation/ dehydrogenation and prevent the coking of acidic sites. NiSx/HY performs similarly to Ru, Ir and Rh-based catalysts, and a synergetic promoting effect is observed for Ni-Ru and Ni-Rh combinations. However, with respect to noble metals such as Ir and Ru under H2S-free conditions, the sulfide counterparts appear much less (if not) hydrogenolytic. As compared to HY, the H-Beta support shows similar performance but promotes cracking
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Benkada, Assma [Verfasser], Wolfgang [Akademischer Betreuer] Bensch, and Norbert [Gutachter] Stock. "Synthesis of Thiostannates, Oxo-Thiostannates and Tin-Sulfides Applying Transition Metal Complexes Containing Macrocyclic Amine Molecules : Development of new synthetic routes to synthesize Sn-S and S-Sn-O compounds and investigation of their properties / Assma Benkada ; Gutachter: Norbert Stock ; Betreuer: Wolfgang Bensch." Kiel : Universitätsbibliothek Kiel, 2020. http://d-nb.info/1222974169/34.
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Saifi, Ali. "Contribution à l'étude des propriétés magnétiques des systèmes spinelles isolants CdCr2xIn2-2xS4 et ZnCr2xGa2-2xO4 : phases type verre de spin." Paris 6, 1986. http://www.theses.fr/1986PA066519.
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Ces systèmes présentent la percolation et la frustration. Le premier composé est ferromagnétique, tandis que le second présente des interactions antiferromagnétiques. On étudie en fonction de x les transitions de ces composés. Les transitions de phase du gallate ont été étudiées par effet Mössbauer. On a mis en évidence que pour x0,75 l'ordre magnétique tend vers un ordre caractéristique de la "vraie" phase verre de spin.
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Těšík, Jan. "Luminiscence polovodičů studovaná rastrovací optickou mikroskopií v blízkém poli." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-320110.
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This work is focused on the study of luminescence of atomic thin layers of transition metal chalkogenides (eg. MoS2). In the experimental part, the work deals with the preparation of atomic thin layers of semiconducting chalcogenides and the subsequent manufacturing of plasmonic interference structures around these layers. The illumination of the interference structure will create a standing plasmonic wave that will excite the photoluminescence of the semiconductor. Photoluminescence was studied both by far-field spectroscopy and near-field optical microscopy.
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Erdmann, Svenja [Verfasser]. "The effect of inorganic components on organic matter transformation under hydrothermal conditions : constraints from laboratory experiments studying the abiotic oxidation of n-octane in presence of iron mineral assemblages, additional transition metals and dissolved sulfate / Svenja Erdmann." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover (TIB), 2015. http://d-nb.info/1070285196/34.
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ANIPSITAKIS, GEORGIOS P. "COBALT/PEROXYMONOSULFATE AND RELATED OXIDIZING REAGENTS FOR WATER TREATMENT." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1130533674.
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Kuba, Jakub. "Studium fotoluminiscence tenkých vrstev MoS2." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-254284.
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The thesis deals with study of thin layers of transition metal dichalcogenides, especially of molybdenum disulfide. Nanostructures were fabricated on two-dimensional crystals of MoS2 and WSe2. Within followed analysis attention was paid to the photoluminescence properties. In the thesis transition metal dichalcogenides are reviewed and description of the modified process of preparation by micromechanical exfoliation is given.
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Berretil, Slimane. "Proprietes electroniques des semi-conducteurs magnetiques gamo : :(4)s::(8), gamo::(4)se::(8), gamo::(4)se::(4)te::(4) et ganb::(4)s::(8)." Paris 6, 1987. http://www.theses.fr/1987PA066262.
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Etudes effectuees en vue de preciser la nature des electrons qui participent ala conduction et au magnetisme de ces composes. Les composes, caracterises par la presence d'amas tetraedriques des ions metalliques mo et nb dans les bas etats d'oxydation, revelent des proprietes de magnetisme itinerant repondant au modele de stoner-wohlfarth avec les densites d'etats les plus elevees observees dans des composes intermetalliques 3d ou 4d. La rpe a confirme que les raies observees correspondant aux ions metalliques dans un etat s = 3/2 (ions mo**(3+) et nb**(3+)); leur elargissement est d'origine dipolaire retrecie par echange et les valeurs des integrales d'echange obtenues sont en bon accord avec celles obtenues a partir des temperatures de curie
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Wahbi, Mernissi Khalid. "Étude exploratoire du système AG-HG-S : Synthèse de l'imitérite AG::(2)HGS::(2) stabilité thermique, caractérisation électrique et optique." Nancy 1, 1989. http://www.theses.fr/1989NAN10090.
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Synthèse par précipitation de solutions aqueuses de nitrates de HG et de AG et de sulfure de NA A 70**(O)C A 10 <OU= PH <OU= 11. Détermination de la stabilité thermique par analyse enthalpique différentielle : décomposition en argentite et cinabre à 215**(O)C. Étude des propriétés électriques entre température ambiante et 185**(O)C: AG::(2)HGS::(2) est un semi-conducteur, mais la conductivité ionique, nulle à température ambiante, atteint 25% de la conductivité totale à 165**(O)C. Analyse de l'absorption optique entre 0,4 et 125 MU M : elle est très proche de celle des constituants et la théorie des groupes permet d'expliquer la variation des pics d'absorption dus aux vibrations du réseau
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Cheaito, Bassam. "Contribution à l'étude de la supraconductivité anormale du composé EuMo6S8." Grenoble 1, 1986. http://www.theses.fr/1986GRE10100.
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Etude de monocristaux de eumo::(6)s::(8) et d'echantillons frittes de yb::(1,2-x)eu::(x)mo::(6)s::(8) basee sur des mesures de transport sous pression et sous champ magnetique, des mesures de la susceptibilite magnetique et des mesures rpe; mise au point d'un dispositif automatise de mesures de transport. Correlations entre la temperature de transition structurale, la remontee de la resistivite a basse temperature et la transition supraconductrice sous pression; effets de la composition des echantillons frittes. Mise en evidence d'une valeur tres elevee du coefficient de chaleur massique electronique. Discussion des proprietes anormales dans le cadre d'un modele de melange de phases triclinique et rhomboedrique et d'un modele de supraconductivite propre
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Prouzet, Eric. "Ordre local dans de nouvelles formes de NiPS obtenues par chimie douce et par intercalation de lithium." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37617740f.
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Alvarez, Gonzalez Eleuterio. "Substitution d'ethers et d'alcools allyliques par differents nucleophiles en presence de complexes de nickel(0) : synthese stereoselective des dienes-1,4 a partir des sulfones dieniques avec le chlorure d'isopropylmagnesium en presence de sels de." Paris 6, 1987. http://www.theses.fr/1987PA066064.
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Giroud, Monique. "Etude expérimentale de supraconducteurs magnétiques : diagramme de phase de HoMo6S8 monocristallin et supraconductivité induite dans l'état ferromagnétique." Grenoble 1, 1987. http://www.theses.fr/1987GRE10123.
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Etude par des mesures de susceptibilite, de conductivite electrique et d'aimantation. Etude detaillee du diagramme de phase de homo::(6)s::(8); observation de transitions supraconductrices lors de cyclages en champ et en temperature, bien au-dessous du point de curie. Mise en evidence d'effet exceptionnellement faibles de l'echange sur la supraconductivite a partir de l'etude des champs critiques et de leur anisotropie; les transitions dans l'etat ferromagnetique sont expliquees par la reduction de l'induction magnetique lorsque le champ est antiparallele a l'aimantation spontanee. Recherche des effets des interactions d'echange sur la pente du champ critique a tc dans errh::(4)b::(4); mise en evidence d'une supraconductivite residuelle dans l'etat ferromagnetique, associee aux parois de bloch, dans le cas de sner::(4)rh::(6)sn::(18)
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Zhuang, Jui-Yi, and 莊君毅. "Studies of using MoS2-based mixed transition metal sulfides (Iron sulfide,Cobalt sulfide,Nickel sulfide)as anodes of SOFCs." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/91089279498463569581.
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碩士<br>國立成功大學<br>材料科學及工程學系碩博士班<br>96<br>Having high electrical conductivity and high fuel catalytic property is the key issue to select adequate electrode material for solid oxide fuel cell applications. Especially when small amount of hydrogen sulfide is present in common fuels like natural gas, the sulfidation of electrode material needs to be considered. Thus, searching for proper materials that are stable and functional in the H2S-containing environment is imperious and necessary.
Most transition metal sulfides have high electrical conductivity, and provide with the ability of reforming hydrogen sulfide. Hence, they are the potential anode materials for SOFC applications. In this work, molybdenm disulfide, iron sulide, cobalt sulfide, and nickel sulfide was investigated as the anode material of SOFCs. Among them, molybdenm disulfide is an n-type semiconductor and have high hydrogen sulfide reforming capability. However, the electrical conductivity of molybdenum disulfide is only around 1 S/cm at 800℃ in reducing atmosphere. The transition metal sulfides, such as iron sulfide, cobalt sulfide, and nickel sulfide, have conductivity of 100~400 S/cm at 800℃ in reducing atmosphere. Therefore, MoS2 was mixed with transition metal sulfide individually to enhance its conductivity in this study. The structural variation, electrical conduction, and polarization were examined using XRD, AC-impedance spectroscopy and current-interrruption methods.
The results show that most MoS2-transition metal sulfides mixtures remain unreacted two phases. Except for MoS2-FeS system, FeMo2S4 with defective NiAs structure was observed when the mixture of MoS2 and FeS was heated in reducing atmosphere at 800oC for 48h. Based on the results from ESCA analysis, the formation of FeMo2S4 is mainly due to the presence of divalent iron ions and trivalent molybdenum ions. The compatability of mixed sulfide with yttria stabilized zirconia(YSZ) electrolyte were examined using Dilamatic instrument. The thermal expansion coefficient of YSZ was found to be 10.26 ×10-6K-1 . Among sulfide mixtures, MoS2-FeS system exhibits very high thermal expansion coefficient of 22.09 ×10-6K-1 due to the contribution of FeS. For the systems of MoS2-Ni3S2 and MoS2-CoS, the thermal expansion coefficients were measured to be 10.96×10-6K-1 and 8.56×10-6K-1, respectively. Thus, MoS2-Ni3S2 and MoS2-CoS systems are thermally compatible with YSZ. The results of overpotential measurements indicate that the polarization of sulfide anode is significantly less than typical Ni-YSZ anode. The high polarization of Ni-YSZ is caused by the formation of nickel sulfide that suppress the path of gas transport. The reduced polarization in mixed sulfides is contributed by the presence of MoS2. According to H2S reforming experiments, it was observed that the decomposition of H2S started at temperature as low as 350oC when MoS2 is present. Without MoS2, the thermal decomposition of H2S began at 500oC.
Based on the results in this study and comparing the phase stability, polarization behavior,and H2S catalytic properties of mixed sulfides versus Ni-YSZ, MoS2-Ni3S2 and MoS2-CoS may be potential anode materials for SOFC applications when the H2S-containing fuel is used.