Teses / dissertações sobre o tema "Disulfure de molybdène (MoS2)"
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Casademont, Hugo. "Semi-conducteurs 2D pour l’électronique flexible : évaluation du potentiel du MoS2 monocouche en tant que matériau de canal". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS365/document.
Texto completo da fonteThis PhD thesis is dedicated to the assessment of the potential of monolayers of molybdenum disulfide (MoS2) as a N-type channel material for flexible electronics. This 2D semiconductor of atomic-scale thickness is chemically stable, mechanically robust and has a direct bandgap of 1.9 eV. This work includes the synthesis of MoS2 monolayers by Chemical Vapor Deposition (CVD) and the characterization of this material. The MoS2 monolayers were integrated in air-stable N-type transistors. The study highlighted the impact on the device performances of both the environment and the resistances at the MoS2/metal interfaces. Electronic mobilities of 20 cm²/(V.s) in combination with ION/IOFF ratios > 106 were achieved. These performances allowed integrating MoS2 monolayers in flexible transistors. This work was combined with the study of electrografted organic ultrathin films used as gate dielectrics and their integration in MoS2 transistors. This thesis shows that MoS2 monolayers are a viable option for flexible electronics operating at low bias, in particular when they are associated with ultrathin organic dielectrics
Rabaso, Pierre. "Nanoparticle-doped lubricants : Potential of Inorganic Fullerene-like (IF-) molybdenum disulfide for automotive applications". Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0103/document.
Texto completo da fonteThe growing environmental concerns, along with the continuous increase in the price of fossil fuels, have highly motivated car manufacturers worldwide to improve the efficiency of their vehicles. The tribological properties of engine and gearbox lubricants have a significant impact on the global efficiency of vehicles, as they contribute to reducing friction in many contacts and allow the downsizing of various components by providing their surfaces with anti-wear protection. The recent breakthroughs in nanoparticle synthesis have opened new prospects in terms of lubricant additivation, with the discovery of the excellent friction and wear reducing properties of nanoparticles such as Inorganic Fullerene-like (IF-) molybdenum or tungsten disulfides. The tribological potential of IF-MoS2 for automobile applications was investigated in this work. The respective influences of nanoparticle size and structure were first of all studied, revealing that poorly crystalline nanoparticles were more efficient in maintaining low-friction tribofilms on steel substrates in severe boundary lubrication regimes regardless of size (for the range studied). All the nanoparticles tested however showed similar performances when proper oil recirculation was ensured, providing a continuous feeding of the contact in nanoparticles. The IF-MoS2 nanoparticles lost their lubricating abilities when added to fully-formulated lubricants. This behavior was attributed to the presence of dispersants in the oil, which dispersed the nanoparticles effectively but prevented them from forming tribofilms on the rubbing surfaces. The well-dispersed IF-MoS2 were shown to enter the contact and exfoliate, but an excessive adsorption of the dispersants on the released MoS2 platelets and/or the steel surfaces is thought to prevent tribofilm adhesion. A balance between nanoparticle dispersion and tribological performance was then found, by using very low concentrations of dispersants. The behavior of nanoparticle-doped oils in various scenarios related to automobile applications was finally explored. The IF-MoS2 provided significant friction and wear reduction at ambient temperature and in milder rolling/sliding test conditions, for smooth and rough surfaces. The risks related to the presence of nanoparticles in the oil in full-film lubrication regimes were partially lifted, with no significant influence on friction witnessed for all the test conditions considered. The ability of IF-MoS2 nanoparticles to protect steel surfaces from surface-initiated Rolling Contact Fatigue was finally shown
Normant, Antoine. "Durabilité d’interfaces tribologiques lubrifiées par des couches minces sous ultravide". Electronic Thesis or Diss., Ecully, Ecole centrale de Lyon, 2024. http://www.theses.fr/2024ECDL0016.
Texto completo da fonteThe use of thin films for the tribological functionalization of surfaces is widespread in industry. The aim is to control wear or friction, depending on whether the coatings are hard or solid lubricants. In the context of dry contacts under vacuum, where adhesive phenomena predominate, mater transfers between surfaces occur. This leads to the formation of an interface that determines the tribological behavior of the contact. Following an analysis of the degradations of a thin layer of TiN in contact with steel in a real mechanism, an appropriate experimental modelling was set up to reproduce those degradations on model surfaces in an environment control tribometer. The sphere/plane geometry of the contact, with the coating deposited on the ball, induces a continuous exposure of the coating to friction, thus accelerating the appearance of degradation. This modelling uses a unique tribometer, enabling tribological experiments to be carried out in all directions of the plane and the measurement of displacement resisting forces in all directions of space, thanks to its 6-axis force sensor. This experimental study highlighted the formation and rupture processes of adhesive junctions in contacts involving commercial thin films of various natures, whether hard (TiN) or with solid lubrication capabilities (MoS2 and hydrogenated amorphous carbon a-C:H). The tribological behavior of the lubricating coatings is compared with that of the hard TiN coating. An analysis of the transfer phenomena in these contacts highlights the distinction between the durability of the coating (tearing for hard coatings and wear for soft ones) and the durability of the contact (characterized by the appearance of macroscopic seizure). The durability of the contact is intrinsically linked to the evolution of the interfacial material formed during the transfer of matter between surfaces, resulting from adhesive phenomena. This study highlights the diversity and complexity of surface modifications induced by friction. An original approach, based on the crossing of friction tracks, converts the tribometer into an analytical tool. It allows to dissociate the respective roles of the various surface modifications on the tribological behavior of the contact. This approach has been applied to the specific case of friction between steel and a thin layer of amorphous hydrogenated carbon
Hadouda, Hamid. "Etude du disulfure de molybdene : mos#2 des premiers depots aux couches minces photoconductrices". Nantes, 1996. http://www.theses.fr/1996NANT2016.
Texto completo da fonteZavala, Sanchez Luz Adela. "Supported metal disulfide (TMS) catalysts for ultra-deep HDS : coupling of IR spectoscopy and microscopy for a deeper insight into active sites". Thesis, Normandie, 2019. http://www.theses.fr/2019NORMC258.
Texto completo da fonteThis work was focused on obtaining an atomic scale characterization of the (Co)MoS2 and (Ni)WS2 slabs of hydrotreating catalysts supported on alumina and to determine the impact of citric acid (CA) addition. In this study, advanced techniques were implemented such as low temperature CO adsorption followed by IR spectroscopy (IR/CO), DFT calculations and high resolution electron microscopy observations in transmission mode and by STEM HAADF.On the non-promoted W and Mo catalysts, CO adsorption makes it possible to discriminate between the sites of the M- and S- edges of the TMS slabs. The determination of the molar extinction coefficients of the adsorbed CO bands allows the morphology of the slabs to be deduced. HR STEM HAADF confirms that the addition of CA modifies the morphology of the TMS slabs from a truncated triangle to a hexagonal shape.On the promoted NiW and CoMo catalysts, electron microscopy shows that the addition of CA decreases the size of the TMS slabs and also leads to the creation of very small clusters (<1 nm). The analysis of isolated particles by HR STEM HAADF allows identifying the nature of the atoms on the edge of the TMS slabs. Thus microscopy and IR/CO show that within the same sulfide slabs, can coexist edges that are fully promoted and partially promoted
Sampieri-Croda, Alvaro. "Synthèse de catalyseurs à base de sulfures de molybdène et nickel-molybdène supportés sur oxydes mésoporeux MCM-41 et SBA-15 : Application en hydrodésulfuration". Paris 6, 2005. http://www.theses.fr/2005PA066071.
Texto completo da fonteBui, Hong Son. "Etude de l'influence physicochimique des environnements gazeux sur le comportement tribomécanique du bi-sulfure de molybdène MoS2". Poitiers, 2012. http://www.theses.fr/2012POIT2331.
Texto completo da fonteThe aim of this study is to characterize experimentally and theoretically the evolution of the friction coefficient of molybdenum disulfide MoS2 in various gases such as in the high vacuum at 10-5 Pa and in the various components gases of the ambient air. We present and discuss the experimental results of the contact XC48/ MoS2/XC48. Our tribological tests are performed on a pin on disk tribometer which located in an ultra high vacuum chamber and which is equipped with one system of gas introduction valves. To clarify the effect of each gas, tribological tests were carried out in the high vacuum (10-5 Pa), in the helium and in the argon at 105 Pa as inert gases, in the nitrogen and in the carbon dioxide at 105 Pa as the less reactive gases, in the oxygen at 105 Pa as the strong reactive gas, in the water vapour with a permanent dipole and in the air ambient with or without the presence of moisture. The tribological nature of molybdenum disulfide MoS2 obtained in high vacuum will be discussed. The influence of gases on the tribological behaviour of molybdenum disulfide will be also discussed and interpreted according to the dipolar character of these gases. A simple calculation of interaction forces MoS2-gas in terms of Van der Waals forces will be presented. Moreover, the influence of Van der Waals forces according to the nature of the gas around the tribocontact on the elastic tensor or on the stress of cleavage of the anisotropic lamellar layers of MoS2 will be discussed too
Conan, Françoise. "Contribution à l'élaboration de nouveaux squelettes organiques via l'étude de la réactivité d'un groupe disulfure de carbone coordine au molybdène". Brest, 1988. http://www.theses.fr/1988BRES2017.
Texto completo da fonteBarreau, Nicolas. "Elaboration et étude de couches minces de disulfure de molybdène et de dérivés de sulfure d'indium : Contribution à la réalisation de photopiles". Nantes, 2001. http://www.theses.fr/2001NANT2024.
Texto completo da fonteWambeke, Anne. "Description et performances en hydrogénation et isomérisation des sites de MoS2/[gamma]Al2O3 modifiés ou non par des métaux de la première série de transition". Lille 1, 1987. http://www.theses.fr/1987LIL10104.
Texto completo da fonteMok, Jinmyoung. "Etude ultra-sensible en phase de nano-structures par interferométrie optique à balayage en champ proche". Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0086/document.
Texto completo da fonteIn this thesis, near-field scanning optical interferometry (NSOI), which combinesNSOM with interferometer, is proposed for the phase measurement. The shear-forcedetection scheme is applied for distance regulation. The hardware of the systemis constructed by combining various electronic devices, and the operating softwareis coded by LabVIEW. Unwanted background signal is removed by simple calculationbased on interference theory. By using this, the near-field optical measurementand the ultra-sensitive phase investigation of nano-materials are performed. 2D materialssuch as graphene and monolayer MoS2 are investigated. It is shown thatatomic-scale thickness can be resolved by the NSOI. Especially, the grain boundariesof graphene and the seed of MoS2 can be found by phase detection. In addition,direct laser writing (DLW) on silver-containing glass is observed by using NSOM,and NSOI. For the first time, the writing threshold is correlatively observed in thefluorescence imaging and the near-field phase image
Rahali, Radia. "Structuration of SrTiO3 surfaces and MoS2 2D material induced by swift heavy ion irradiation at grazing incidence". Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMC203.
Texto completo da fonteMaterials modification has enabled significant advancements in the technological fields by allowing for precise control and manipulation of material properties. To ensure successful applications, it is crucial to have techniques that offer control over the size, shape, and morphology of the structures created. This thesis explores the use of swift heavy ions (SHI) to create nano- and microstructures on the surfaces of strontium titanate (SrTiO3) and molybdenum disulphide (MoS2) under grazing incidence geometry. The results show that SHI irradiation can induce various surface modifications, such as elongated surface defects, wave-like structures, and amorphization. This research demonstrates that by adjusting the fluence and angle of incidence of the ion beam, periodic wave-like structures can be formed on the surface of SrTiO3. These structures can be deepened to obtain more pronounced valley, which can be used to directly grow two-dimensional materials and obtain heterostructures with well-defined interfaces. The results also demonstrates that SHI irradiation can induce foldings in MoS2 samples. The angle of incidence of the ion beam and the substrate used can control the defects. The choice of substrate can also influence folds density and length. It is shown that using SrTiO3 as a substrate allows the folding with variable lengths without the need for specific crystallographic orientation conditions
Cadot, Stéphane. "Élaboration de monocouches de dichalcogénures de métaux de transition du groupe (VI) par chimie organométallique de surface". Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1075/document.
Texto completo da fonteMoS2, a transition metal dichalcogenide (TMD) possessing a mica-like layered structure, has been widely used over the past century as solid lubricant and hydrotreating catalyst. Since 2010, the discovery of new semiconducting (direct gap) and photoluminescence properties emerging in monolayer MoS2 has attracted much interest, with a wide range of potentialities for next-generation electronics or energy storage devices. Beyond MoS2, this discovery also concerns other TMDs (WS2, NbS2, MoSe2, WSe2,…), displaying a wide variety of electronic and optical properties, and whose combination with other 2D materials (graphene, BN,…) offers outstanding opportunities. While exfoliated materials have provided a convenient way to demonstrate the feasibility of proof-of-concept-devices, the development of reliable synthesis methods allowing the industrial production of monolayer TMDs has now to be investigated.In this booming research field, currently dominated by high-temperature CVD processes which are time-consuming and often require the use of epitaxial substrates, we investigated the potentiality of a low-temperature chemical vapor deposition approach on amorphous SiO2 substrates. This work allowed us to identify suitable precursors for the CVD or ALD of ultrathin amorphous molybdenum or tungsten sulfide deposits below 250°C, and to point out their ability to self-reorganize into crystalline MoS2 and WS2 monolayers upon thermal annealing
Dominguez, Garcia Elizabeth. "Εffect οf the suppοrt οn the activity and mοrphοlοgy οf hydrοdesulfurizatiοn catalysts". Thesis, Normandie, 2017. http://www.theses.fr/2017NORMC258/document.
Texto completo da fonteThe influence of the support effect on the sulfide phases formation, i.e. morphology, sites dispersión, structure and catalytic activity for hydrotreating catalysts was studied. The study started by Mo catalysts and followed by CoMo catalysts supported on alumina silica and titania. The support effect appeared to be the key factor to control the morphology of MoS2 slabs. The morphology was studied using a powerful technique so-called IR/CO, i.e. CO adsorption followed by FTIR spectroscopy. This method allows the distinction of two types of edge exposed on the MoS2 slabs so-called M- and S-edge and then permits the study of the morphology by the S-/M-edge ratio. Thus, for a weak interaction MoS2-support deformed hexagon morphology was detected whereas for a strong interaction triangle morphology was observed. These different morphologies were used to study the Co localization by the same method, IR/CO. This method also allows the distinction between non- and promoted sites as well as Co located on M- and S-edges. Hence, the comparison between S-/M-edge ratio and promotion degree (promoted/non-promoted sites ratio) showed that Co is present on both M- and S-edges for the three CoMo supported catalysts. Additionally, a detailed study showed that Co preferentially decorates S-edge sites. Consequently, the CoMoS site structures for each catalyst has been studied by 2D IRIS method. This novel method developped in LCS allows the resolution of overlapping IR/CO bands which were previously a limitation for CoMoS sites characterization. This advance in the CoMo characterization lead to the study of detailed CoMoS structure. After the assignment of three bands which are observed in the promoted range of IR/CO spectra, it appeared that S-edge sites were partially promoted by Co, whereas M-edge sites could be partially and totally promoted by Co. The different proportion of those sites have an effect on HDS (hydrodesulfuration) reactivity. Thus, higher intrinsic activity was found for M-edge partially promoted by Co followed by totally promoted and finally the S-edge partially promoted sites
Takeda, Sho. "A Study of the Consolidation Process of Cu from Powder to Plate by Compression Shearing Method". Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEC047.
Texto completo da fonteCompression shearing method at room temperature (COSME-RT) is a molding technique for materials (especially metals) from powder to plate by applying simultaneous biaxial force at room temperature and an ambient atmosphere. COSME-RT differs from conventional molding techniques in that it can fabricate materials without a heating process and can thus develop new materials that cannot be formed by conventional methods. However, the consolidation mechanism of materials by COSME-RT has not been clarified because of the difficulty of controlling the process. To control the consolidation process of metal materials by COSME-RT, I attempted two experiments to control the shearing force: (1) the suppression of the shearing force by dispersing solid lubricant particles into Cu powder particles; and (2) the unidirectional friction test on the uniaxial compressed powder sample to create and observe the change of the bonding condition in the depth direction of the sample. As a result, I successfully obtained new knowledge about the consolidation process of Cu plate from powder by COSME-RT and built the new consolidation model of Cu by COSME-RT
Ullberg, Nathan. "Visibility and charge density imaging of 2-dimensional semiconductors and devices studied using optical microscopy techniques IRM and BALM". Electronic Thesis or Diss., université Paris-Saclay, 2023. http://www.theses.fr/2023UPAST219.
Texto completo da fonteOptical microscopy has played an instrumental role in 2-dimensional (2D) materials research. In particular, the phenomenon of thin-film interference of light has been leveraged to improve contrast and vertical resolution of 2D materials down to the sub-nanometer scale, often via Fabry-Pérot (FP) thin-film resonators. In this thesis, interference reflection microscopy (IRM) and backside absorbing layer microscopy (BALM), both of which harbor FP effects, are developed and utilized to study visibility and topographic inhomogeneities of the 2D semiconductor MoS₂. Experimental contrast data are compared against Fresnel-based simulations of contrast. For IRM, an optimal configuration was found by tuning of incident wavelength and top medium refractive index, yielding ≈ 80% contrast. For BALM, the optical properties were measured for both the anti-reflective absorbing layer of nanometric Cr/Au, and an additional insulating AlOₓ layer, where for the first time the contrast spectrum for this system was acquired and simulated, yielding a maximum experimental contrast of ≈ 79% for 2D MoS₂. Simulations of the optical stack across a variable range of aperture stop diameters and FP layer thicknesses predict further improvement of BALM conditions for high-contrast MoS₂ visibility. Additional aspects including z-focus, optical noise, image post-processing, and others were also considered. Building on the visibility aspects, a charge density imaging capability for 2D MoS₂ and other transition metal dichalcogenide crystals was developed by leveraging the charge-dependent complex refractive index near the wavelengths of the excitons. Capacitors and field-effect transistors (FET) of MoS₂ were realized, with multiple in operando experiments performed in widefield at throughputs up to 4 fps. In IRM mode, a liquid electrolyte gate was used, where charging delays and inhomogeneities due to intra- and inter-flake resistances in polycrystalline MoS₂ are presented. For Schottky barrier MoS₂ FETs, the drain versus gate voltage competition for control of the local charge density in the channel was studied for the first time by optical microscopy. Solid-state MoS₂ capacitor devices integrated in a BALM optical stack are also presented for the first time, both by experiments and simulations. A preliminary solid-state FET device was realized, exemplifying the powerful idea of combining optical charge imaging with electrical characterization in tandem. This work on visibility and charge imaging aspects aims to widen the role and impact of optical microscopy techniques in the space of 2D materials research
Ninh, Thi Kim Thoa. "Une nouvelle approche dans l’évaluation de l’effet de support des catalyseurs d’hydrodésulfuration". Thesis, Lyon 1, 2011. http://www.theses.fr/2011LYO10028/document.
Texto completo da fonteThe main objective of this work was to evaluate the support and the promoting effect on the catalytic properties of HDS catalysts. In order to obtain appropriate catalytic systems, we applied the “acac method” which consists to add the promoter as an acetylacetonate complex (of Co, Ni or Fe) onto the supported molybdenum sulfide (on γ-Al2O3, SiO2, TiO2 and ZrO2). The various solids obtained were characterized by TEM, IR(CO) and XPS in particular to quantify the active phases, and then they have been tested in the HDS reactions of thiophene and 4,6-DMDBT. The catalytic activity has been correlated to the characterization datas by a new approach which consists in calculating the apparent catalytic activity by NiMoS or CoMoS site. This approach showed that the quality of the active sites is the best on SiO2 and comparable on γ-Al2O3, TiO2 and ZrO2. Moreover, this “acac method” allowed us to study supported CoNiMoS catalysts synthesized by adding Co and Ni either simultaneously or successively to MoS2. This study represents an important experimental contribution which allow to discuss the hypothesis developped in theoretical studies about the different affinities of Co and Ni for the S-edge and Mo-edge on γ-Al2O3 and TiO2
Baubet, Bertrand. "Influence de la morphologie 2D de la phase active sur la sélectivité des catalyseurs sulfures en HDS des essences". Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10067.
Texto completo da fonteThis thesis examines the influence of the morphology of particles of molybdenum sulfide on selectivity of hydrotreating catalysts. Nanoparticles of active phase present two types of edges called “M-edge” and “S-edge” which may lead to different reactivities. The change in morphology of the 2D sheets could change the proportions of M and S edges exposed and thus the catalytic properties of sulfide catalysts. For this, non-promoted (Mo) and promoted (CoMo) catalysts, supported on alumina were prepared by dry impregnation and sulfide in various conditions (gas and temperature). Catalytic tests in selective hydrodesulfurization (HDS) of FCC gasoline (selectivity HDS /HYD) were then used to assess the impact of the morphology based on geometrical models which were constructed with DFT calculations and experimental characterizations (TEM, IR (CO), TPR, XPS). The results for Mo catalysts seem to confirm the influence of the 2D morphology selectivity HDS / HYD, M-edge appearing to be the most selective for non-promoted catalysts. They also highlight the importance of the reducibility more or less pronounced of the edges on the catalytic properties, especially on the M-edge. The different conditions of sulfidation seem to affect the morphology of the particles but also the specific chemical properties at each edge. Regarding to the promoted catalysts, the different conditions of sulfidation appear to act primarily at the distribution of the promoter between the M and S edges. However, interactions with the carrier appear to constitute an obstacle to promoting effects. In this context, sulfidations at high temperature in pure H2S lead to obtain significant gains in activity and selectivity. These results appear to be due to weak interactions with the carrier and to the presence of the promoter on the S-edge which could promote the HDS reaction and limit the HYD reaction. Finally, the interpretations made in terms of 2D morphology tend to confirm that this parameter can be an interesting line of development for hydrotreating catalysts. Optimization of the sulfidation conditions could effectively allow to vary the morphology and the rate of decoration of promoted catalysts which significantly improve the activity and selectivity