This master’s thesis deals with the plasmon resonance of the nanostructures of several selected tungsten oxides using Fourier transform infrared spectroscopy (FTIR spectroscopy). The physical principles of the plasmonics, the characteristics of the materials used, as well as the principle of operating and measuring on the FTIR spectrometer, are described in the first part of this thesis. The second part is focused on the preparation of samples and performing measurements on the FTIR spectrometer. This part ends by representing the final spectra and the results obtained.

The subject of this Diploma thesis was study of wear resistant deposits, including appropriate basic and filler materials and welding technologies suitable for a particular application of hard carbide overlays of blade mixer for foundry sand. Analysis of suitable filler materials focused on extreme abrasion and select tungsten carbide hardfacing, together with a selection of appropriate overlays welding methods for welding tungsten carbide, including the conditions and parameters surfacing. The practical part deals with the design and evaluation of the experiment, three samples welding of non-alloy structural steel, tungsten-carbide hardfacing, technology MCAW - WC flux cored electrode in protective active gas.

In the present thesis structure, morphology, chemical and electronic properties of the Pt - Au/tungsten oxide model system were investigated by means of RHEED, AFM and PES. The epitaxial tungsten oxide thin films were prepared by oxidation of W(110) single-crystal surface using a RF oxygen plasma source followed by thermal annealing. Gold and Platinum were deposited "in-situ" by evaporation. Gold or platinum deposition led to the growth of oriented particles having (111) epitaxial plane as well as to the growth of polycrystalline phase. Platinum encapsulation was proved by CO adsorption observed by SRPES. Deposition of the second metal led to the formation of core - shell bimetallic clusters. Detail structure of the bimetallic system depends on the order of deposited metals and the substrate temperature. Thermal stability of the system was investigated by heating up to 600 řC.

Tungsten oxide thin films were prepared by vacuum evaporation on surfaces of Pd(111), Cu(111), Cu(110) and Cu(100) single crystals and studied by RHEED, XPS and AFM methods. The tungsten oxide deposition was done at temperatures from 300 řC to 400 řC in UHV or in oxygen atmosphere. The best deposition conditions - substrate temperature of 400 řC and oxygen atmosphere - were found resulting in growth of epitaxial and only partially reduced thin films. Thin films grown on the Pd(111) and Cu(111) surfaces consisted of two phases: a nearly atomically flat phase with (100) epitaxial plane and a phase formed by three dimensional particles with (111) epitaxial plane. Thin film deposited on Cu(100) also consisted of two phases: a flat film with (100) epitaxial plane and self-organised 1D structures parallel to Cu[010] and Cu[001] directions. Thin film prepared on the Cu(110) surface contained solely 1D structures parallel to Cu[1-10] surface direction. Capability of the partially reduced thin films for oxidation was studied. We applied oxidation using RF oxygen plasma, O2 exposure at elevated temperature and exposure to atmosphere. Thermal stability of the WO3/Cu(110) system was also investigated by heating up to 620 řC.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemistry, 1982 / Includes bibliographical references. / by Lynda Gail Sturgeoff. / Ph. D. / Ph. D. Massachusetts Institute of Technology, Department of Chemistry

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第20484号 / エネ博第353号 / 新制||エネ||70(附属図書館) / 京都大学大学院エネルギー科学研究科エネルギー変換科学専攻 / (主査)教授 木村 晃彦, 教授 星出 敏彦, 教授 今谷 勝次 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

No description available.

Many organometallic reactions are solvent-dependent, suggesting solvent molecules interact with reaction intermediates. Studies of the solvent exchange reaction of group 6 transition metal carbonyls with moderately binding ligands have provided insight into these interactions, however, studies of the mechanism for this reaction with weakly binding ligands have not been performed. Experiments were conducted on the nanosecond time scale in methylcyclohexane over the temperature range of 4 to 44 °C using Step Scan FTIR (SS FTIR) spectroscopy with weakly binding ligands benzene and mesitylene. Upon photolysis of the metal hexacarbonyls, the kinetically favored product (M(CO)5(solv)), decays following pseudo-first-order kinetics to the thermodynamical favored product, M(CO)5(L). The decay is fit using a single exponential decay with a single exponential instrument response function, time zero and an offset. An Arrhenius plot yielded activation energies of 23.7 kJ/mol (M = Mo, L = benzene), 35.1 kJ/mol (M = W, L = benzene) and 29.8 kJ/mol (M = Mo, L = mesitylene). DFT calculations using NWCHEM gave binding energies of 45.8 and 54.3 kJ mol-1 for Mo(CO)5C6H12 and W(CO)5C6H12. The experimental and computational results suggest the exchange mechanism proceeds through an associative pathway, were slightly negative values of the entropy of reaction denote that the transition state has greater metal solvent bond breaking character then the more moderately binding ligands in the literature. Density Functional theory was used to calculate C-O vibrational frequencies of metal carbonyl complexes measured in our work and other complexes from the literature, with density functionals B3LYP, M06 and M06-L. Measured and computational frequencies were compared to obtain both an overall vibrational shift and a scaling factor. Scaling factors were found to be 0.9519±0.0095 for B3LYP, 0.9429 ± 0.0087 for M06 and 0.9565 ± 0.0095 for M06-L with overall shifts of 102 ± 16, 121 ± 15, 93 ± 17 cm-1, respectively. The molybdenum mediated Pauson-Khand reaction, a [2+2+1] cyclo-addition begins very similarly to the solvent exchange reaction on molybdenum. The initial product, the solvated complex, decays away with pseudo-first-order kinetics as the solvent is replaced by the C-C triple bond in 2-(2-propen-1-yl)-2-(2-propyn-1-yl)-,1,3-diethyl ester. An Arrhenius plot over the temperature range of -8 to 20° C yielded an energy of activation of 15.6 kJ/mol.

Yes / Titanium alloy Ti-6Al-4V is known for both its excellent mechanical properties and its low surface hardness. This study explores a two-step process for depositing a hard nanocrystalline coating onto the surface of the Ti-alloy, followed by surface melting, which embeds hard nanoparticles into a thin surface layer of the alloy. The treated surface layer was studied using X-ray diffraction, scanning electron microscopy, and Vicker's micro-hardness testing. The results of the study show that the surface of the Ti-6Al-4V alloy can be successfully hardened by embedding nanosized Al2O3 particles into the surface using gas tungsten arc welding to melt the surface of the material. Surface melting the Ti-6Al-4V alloy with a 50A welding current produced the maximum microhardness of 701 HV0.2kg. The micro-hardness of the treated surface layer decreased with the increasing size of the nanoparticles, while the roughness of the surface increased with the increasing welding current. The heat input into the surface during the surface melting process resulted in the formation of various intermetallic compounds capable of further increasing the hardness of the Ti-6Al-4V surface.

High surface area tungsten oxynitride samples have been prepared by the temperature programmed reaction (TPR) of W0₃ with NH₃. All samples were characterized by X-ray diffraction (XRD), nitrogen physisorption, and CO chemisorption. In addition, some sample compositions were determined by elemental analysis. Samples were prepared at various heating rates (β), allowing a Redhead analysis to be carried out giving an activation energy of nitridation of 109 kJ mol⁻¹. A heating rate of 0.016 K S⁻¹ gave optimum synthesis conditions. Solid state intermediates were studied by interruption of the temperature program at various stages. No distinct suboxide phases formed along the synthesis path were found using XRD. An increase in surface area, CO uptake and nitrogen weight content, were found to occur as the reaction progressed. Reactivity experiments showed reasonable hydro deoxygenation (HDO) and hydrodenitrogenation (HDN) activities, but little hydrogenation (HYD) or hydrodesulfurization (HDS) activities. / Master of Science