Physical Sciences and Mathematics Commons^™

Characterization And Luminescence Dynamics Of Mgf2:W Ceramics, A.V. Strelkova, V. M. Lisitsyn, L. A. Lisitsyna, T.A. Koketai, D. A. Mussakhanov, Zh.T. Karipbayev, A. M. Zhunusbekov

Eurasian Journal of Physics and Functional Materials

This study delves into the synthesis and characterization of luminescent ceramics based on tungstenactivated magnesium fluoride (MgF₂) complemented with varying concentrations of lithium hydroxide (LiOH). Utilizing a distinctive sintering process conducted in an open-air milieu under robust radiation conditions, we successfully synthesized a series of tungsten-activated ceramics. Study revealed that the resultant ceramics prominently display luminescent properties, which can be excited by UV radiation in the spectrum of 200-300 nm, as well as by high-energy electron fluxes. The spectral characteristics of these ceramics, in terms of band position, half-width, and excitation spectra, are strikingly analogous to those observed …

Luminescent Properties Of Baxmg(2−X)F4:W Ceramics, T.A. Koketai, A.V. Strelkova, A.M. Zhunusbekov, Zh.T. Karipbayev, L.A. Lisitsyna, A.M. Chakin

Eurasian Journal of Physics and Functional Materials

Ceramics based on alkaline earth metal fluorides activated by tungsten has been obtained by radiation synthesis. The synthesis was realized by direct action on the mixture with an activator of a powerful flow of high-energy electrons without the use of any additives to facilitate the synthesis. It has been established that the resulting ceramics have luminescent properties characteristic of tungsten-activated materials based on metal fluorides.

Seven Coordinate Molybdenum And Tungsten Complexes Containing Tpm And Tpm Derivatives And The Impact Of Ligand Substitution On Nmr Chemical Shifts, Cole Seager

Undergraduate Honors Thesis Collection

A series of known and new seven coordinate molybdenum and tungsten complexes of tris(pyrazolyl)methane (Tpm) and substituted Tpm, [TpmM(CO)3X]+, have been synthesized. Depending on the identity of X, (bromo, iodo, hydrido) and the substitution of the Tpm ligand, substantial chemical shift differences are observed for the hydrogen on the central carbon of the Tpm ligand. Factors impacting the chemical shift of the hydrogen on the central carbon of the Tpm ligand, such as the electron donating ability of the Tpm ligand and the electronegativity of the additional ligand on the metal, will be discussed.

Increasing The Longevity Of Tungsten Filaments In A Zone Refiner, Byron D. Greenlee

Senior Theses

Zone refining is used for its ability to purify material and grow single crystals. To produce these single crystals, a suspended molten zone, generated by electron bombardment, passes along the polycrystalline stock. During a zone refining run, the filaments that produce the electron bombardment can fail. In this project, the longevity of tungsten filaments in a zone refiner was investigated. A new bombardment geometry was constructed to attempt to increase the longevity of the filaments. The new geometry had a shield machined into it to prevent line-of-sight impurities originating in the molten zone from striking the filaments. It was found …

The Electrochemical Behavior Of Molybdenum And Tungsten Tri-Nuclear Metal Clusters With Ethanoate Ligands, Edward Nelson Kennedy

Browse all Theses and Dissertations

The goal of this research was to study the electrochemical behavior of tri-nuclear clusters of molybdenum and tungsten. In addition, the feasibility of using these clusters as catalysts for the purpose of oxidizing ethanol was investigated. Four tri-nuclear cluster compounds were studied: hexa-Mu2-acetatotriaquadi-Mu3-oxotrimolybdenum (IV, IV, IV) trifluoromethanesulfonate [Mo3O2(O2CCH3)6(H2O)3](CF3SO3)2, hexa-Mu2-acetatotriaquadi-Mu3-oxodimolybdenum (IV, IV) tungsten (IV) trifluoromethanesulfonate [Mo2W2O2(O2CCH3)6(H2O)3](CF3SO3)2, hexa-Mu2-acetatotriaquadi-Mu3-oxomolybdenum (IV) ditungsten (IV, IV) trifluoromethanesulfonate [MoW2O2(O2CCH3)6(H2O)3](CF3SO3)2, and hexa-Mu2-acetatotriaquadi-Mu3-oxotritungsten (IV, IV, IV) trifluoromethanesulfonate [W3O2(O2CCH3)6(H2O)3](CF3SO3)2.Data was gathered from experimental results with cyclic voltammetry for the four tri-nuclear clusters. Initially, an ionic liquid, EMIBF4 (1-ethyl-3-methylimidazolium tetrafluoroborate), was used as the solvent. Subsequent solvents for use with these …

Materials For Giant Spin Hall Effect Devices, Avyaya Jayanthinarasimham

Legacy Theses & Dissertations (2009 - 2024)

Studies presented in this thesis are an effort to control the growth of β W and explore

Development Of A Sample Preparation Strategy For The Determination Of Tungsten In Soil Samples By Inductively Coupled Plasma Mass Spectrometry Using A Response Surface Methodology, Ümran Seven Erdemi̇r

Turkish Journal of Chemistry

An alternative rapid digestion method has been developed for the determination of tungsten (W) in soil samples using fractionation studies and response surface methodology. The digestion method using the Kjeldahl instrument was applied to samples, and soluble tungsten was determined via inductively coupled plasma mass spectrometry. Digestion parameters were selected depending on the results of fractionation studies and optimized using a four-factor and five-level central composite design. The contributions of the phosphoric acid concentration (X$_{1})$, digestion temperature (X$_{2})$, digestion time (X$_{3})$, and hydrochloric acid concentration (X$_{4})$ were evaluated for the determination of W from samples in which its levels were …

Bimetallic Centers With Open Coordination Sites And Magnetic Nanocomposites For Water Remediation, Karen Ventura

Open Access Theses & Dissertations

The development of effective, renewable and environmentally friendly energy sources is essential to supply the growing global energy demands. The use of fossil fuels to fulfill those energy demands have led to the increase of greenhouse gases and water contamination. The extraction of oil and gas requires a large amount of pressurized water, resulting in contaminated water as a byproduct. Meanwhile, ensuring access to clean water is one of the greatest global challenges of this century.

The following study is presented in three sections. In the first section, a bimetallic system with open coordination sites that can be used as …

Synthesis, Reactivity, And Nmr Trends Of Early Transition Metal Compounds, Tabitha Marie Cook

Doctoral Dissertations

This dissertation focuses of three different subjects. The first is the synthesis and characterization of heptacoordinate amidinate compounds. Heptacoordinate compounds are not common, but their structures have been studied. Group 4 amidinate compounds have been used as precursors in the CVD/ ALD processes. Ancillary ligands, such as amidinates, have been used to reduce air-sensitivity of complexes. Reactions of these complexes with water have been used to make metal oxide thin films.

In the first study, the complexes Zr[MeC(NⁱPr)₂]₃Cl [zirconium trisamidinate chloride], Hf[MeC(NⁱPr)₂]₃Cl [hafnium trisamidinate chloride], Zr[MeC(NⁱPr) …

Paragenesis And Geochemistry Of The Calvert Tungsten Skarn Deposit, Pioneer Mountains, Montana, Joshua Messenger

Graduate Theses & Non-Theses

The Calvert tungsten skarn deposit is located in the northern extent of the West Pioneer Mountains, approximately 40 miles southwest of Butte, Montana. The orebody was a significant tungsten producer from 1956-1957 and 1960-1962 during which time the mine produced a total of approximately 113,000 tons of ore averaging 1.10% WO₃. The mine has a measured reserve of 128,000 tons at 1.10% WO₃. The scheelite-bearing deposit occurs within skarn developed in the Pennsylvanian Amsden Formation near or in contact with a satellite pluton of the Late Cretaceous Pioneer Batholith.

Mineral paragenetic studies reveal at least three …

Improvement Of Atomic Layer Deposition Techniques Of Tungsten Using Hydrogen As A Reducing Agent, Jason Kyle Anderson, Dr. David Allred

Journal of Undergraduate Research

Introduction: Traditional micro fabrication processes are confined to a small subset of possible materials due to limitations on etching. They are also confined to low aspect ratio fabrication due to limits in both etching process and stability of thicker film deposition processes. Carbon Nanotube Templated Microfabrication (CNT-M) technology has introduced a dramatically different approach to micro fabrication that fabricates without significant etching processes and achieves thick features with the equivalent of thin depositions. This is achieved by forming the desired structure in carbon nanotubes and then filling, or infiltrating, that structure with the material of choice. Optimal materials infiltration for …

A Study Of Ti-Doped Wo3 Thin Films Using Comparative Theoretical And Experimental Approach, Aurelio Paez

Open Access Theses & Dissertations

Metal oxides like Tungsten Oxide (WO3) are well documented and characterized in the literature, with uses in darkening windows and mirrors, flat computer displays, solar panel cooling, and sensors (of interest in this study). Ti doping of WO3 is less documented and the focus of this study. Sample thin films of pure WO3 and varyingly Ti doped WO3 were prepared using Radio Frequency magnetron sputtering (RF) (13.56 MHz) to grow thin films on a silicon substrate. This study aims to compare multiple Ti doping percentages in WO3 theoretically and then compare with experimental data taken from thin films of various …

Atomistic Simulation Of Plasma Interaction With Plasma Facing Components In Fusion Reactors, Xue Yang

Open Access Dissertations

The interaction between plasma and fusion relevant materials is one of the critical issues in successfully using those materials in Tokamak reactors. This research uses molecular dynamics, kinetic Monte Carlo and binary collision approximation methods to model fusion relevant material bombarded by energetic particles to investigate retention, deposition, sputtering, erosion, blistering effects, diffusion, and so on.

The deuterium bombardment of monocrystalline tungsten was modeled by LAMMPS code using Tersoff type interatomic potential. The deuterium trapping rate, implantation depth, and stopping time in 600-2000 K tungsten bombarded by 5-100 eV deuterium atoms were simulated. Irradiated monocrystalline tungsten became amorphous prior to …

Soil Geochemistry And Pathfinder Element Distribution Associated With The Hillgrove Antimony-Gold-Tungsten Deposit, New England Orogen, Nsw, R Ellsmore, Solomon Buckman, C Simpson

Solomon Buckman Dr.

No abstract provided.

Dynamics Of The Solvent Exchange Reaction Of Weakly Bound Organic Solvents To Group 6 Transition Metal Carbonyls And The Molybdenum Hexacarbonyl Mediated Pauson-Khand Reaction, Richard J. Gates

Theses and Dissertations

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 …

Coordination Chemistry Of Bis(Benzyl)Phosphinate, John S. Maass

Dissertations, Master's Theses and Master's Reports - Open

The work presented in this dissertation deals with the coordination chemistry of the bis(benzyl)phosphinate ligand with vanadium, tungsten and cobalt. The long term goal of this project was to produce and physically characterize high oxidation state transition metal oxide phosphinate compounds with potential catalytic applications.

The reaction of bis(benzyl)phosphinic acid with VO(acac)₂ in the presence of water or pyridine leads to the synthesis of trimeric vanadium(IV) clusters (V₃(µ₃-O)O₂)(µ₂-O₂P(CH₂C6H5)₂)₆(H2O) and (V₃(µ₃-O)O₂)(µ₂-O₂P(CH₂C_{6 …}

Synthesis And Reactions Of A Tungsten Dioxo Complex, Deborah Bryant

Master's Theses (2009 -)

Metal dioxo complexes are largely known for their ability to epoxidize olefins. The importance of these reactions is reflected in the patents for the ARCO and Halcon processes from the late 1960's. It is very difficult to find literature that shows other indications for metal dioxo complexes.

Catalytic olefin dimerization has become significant in the realm of green chemistry for "atom economical" reactions. Many transition metals have been examined as catalysts for olefin dimerization, but the largest volume of work has been performed using group 8 transition metals, particularly nickel, palladium and platinum. This is especially true for the specific …

Soil Geochemistry And Pathfinder Element Distribution Associated With The Hillgrove Antimony-Gold-Tungsten Deposit, New England Orogen, Nsw, R Ellsmore, Solomon Buckman, C Simpson

Faculty of Science - Papers (Archive)

No abstract provided.

Electrochemistry Of Trinuclear Metal Clusters Of Molybdenum And Tungsten In 1-Ethyl-3- Methylimidazolium Tetrafluoroborate, Tracey Lynn Harris

Browse all Theses and Dissertations

The imidazolium based ionic liquid: 1-ethyl-3-methylimidizoliumtetrafluoroborate, (EMIBF4) was synthesized to be used as a solvent for the electrochemical investigation of molybdenum and tungsten. The electrochemical window is about 4.2V after removing traces of impurities such as Cl^- and H₂O. Electronic spectra of metal clusters [Mo₃O₂(O₂CCH₃)₆(H₂O)₃]⁺² ; [W₃O₂(O₂CCH₃)₆(H₂O)₃]⁺² ; [MoW₂O₂(O₂CCH₃)₆(H₂O)₃]⁺² and [Mo_{2 …}

Synthesis And Optical Properties Of Four Oligothiophene-Ruthenium Complexes And Synthesis Of A Bidentate Ligand For C-F Bond Activation, Joseph S. Bair

Theses and Dissertations

Photovoltaic cells and fluorescence sensing are two important areas of research in chemistry. The combination of photon-activated electron donors with electron acceptors provides a strong platform for the study of optical devices. A series of four oligothiophene-ruthenium complexes has been synthesized. Variation in oligothiophene length and bipyridine substitution allowed comparison of these variables on electronic properties. The longer oligothiophenes display lower energy absorption and emission compared to the shorter ones. Aromatic conjugation appears more complete with para-, rather than meta-, substitution. Oligothiophenes and Ru(bpy)32+ are highly fluorescent individually, but fluorescence is quenched when connected. Bonds of carbon to fluorine are …

Diffusion Effect On The Anodic Reactions Of Tungsten, Mustafa Anik, Tuba Cansizoğlu, Si̇nem Çevi̇k

Turkish Journal of Chemistry

Potentiodynamic and potentiostatic polarizations, and a rotating disk electrode technique were used to study the influence of diffusion on the anodic reactions of tungsten (W) in a broad pH range (\sim 0.3--13.5) in H_3PO_4 buffered solutions. The anodic current was controlled totally by the kinetics of H^+ -assisted dissolution below pH 1 (Region A). At around pH 2.5 (Region B), in addition to the kinetics of H_2O-assisted dissolution, specimen rotation had an effect on the current. This observation was attributed mainly to the physical damage to an oxide phase by hydrodynamic effects and partly to the diffusion of surface H_2WO_4(aq) …

Dimethylsulfoxide Reductase: An Enzyme Capable Of Catalysis With Either Molybdenum Or Tungsten At The Active Site, Lisa J. Stewart, Susan Bailey, Brian Bennett, John M. Charnock, C. David Garner, Alan S. Mcalpine

Physics Faculty Research and Publications

DMSO reductase (DMSOR) from Rhodobacter capsulatus, well-characterised as a molybdoenzyme, will bind tungsten. Protein crystallography has shown that tungsten in W-DMSOR is ligated by the dithiolene group of the two pyranopterins, the oxygen atom of Ser147 plus another oxygen atom, and is located in a very similar site to that of molybdenum in Mo-DMSOR. These conclusions are consistent with W L_III-edge X-ray absorption, EPR and UV/visible spectroscopic data. W-DMSOR is significantly more active than Mo-DMSOR in catalysing the reduction of DMSO but, in contrast to the latter, shows no significant ability to catalyse the oxidation of DMS.

Textured Mos 2 Thin Films Obtained On Tungsten: Electrical Properties Of The W/Mos 2 Contact, E. Gourmelon, J. C. Bernède, J. Pouzet, S. Marsillac

Electrical & Computer Engineering Faculty Publications

Textured films of molybdenum disulfide have been obtained by solid state reaction between the constituents in thin films form when a (200) oriented tungsten sheet is used as substrate. The crystallites have their c axis perpendicular to the plane of the substrate. The annealing conditions are T=1073K and t=30 min. The films are stoichoimetric and p type. Such highly textured films are achieved without foreign atom addition (Ni, Co...). It appears, as shown by x-ray photoelectron spectroscopy, that a thin WS₂ layer is present at the interface W/MoS₂. The crystallization process is discussed by a …

^{13}C-And ^{31}P-Nmr Study Of Tetracarbonylbis(Diphenylphosphino)Alkanemetal(0) Complexes Of The Group 6 Elements, Zahi̇de Özer, Sai̇m Özkar

Turkish Journal of Chemistry

Tetracarbonylbis(diphenylphosphino)alkanemetal(0) complexes of the general formula M(CO)_4[(C_6H_5)_2P (CH_2)_nP(C_6H_5)_2] (M: Cr, Mo, W; n: 1, 2, 3) were synthesized from the reaction of M(CO)_4(\eta^{2:2}-1,5-cyclooctadiene) with the appropriate ligand and characterized by means of IR and NMR (^{13}C and ^{31}P) spectroscopy. Spectroscopic data shows that two phosphorus atoms in the complexes are identical and occupy two cis-coordiantion sites in a pseudo-octahedral coordination sphere of the metal. The comparative study of the coordination shift and the ^{31}P-^{13}C coupling constant reveals that two carbonyl groups trans to one of two phosphorus atoms in the diphosphine ligand are shifted toward the lower magnetic field more …

Surface Core-Level Shifts And Atomic Coordination At A Stepped W(110) Surface, D. Mark Riffe, B. Kim, J. L. Erskine, N. D. Shinn

All Physics Faculty Publications

Core-level 4f_7/2 photoemission spectra have been measured from a single, bifacial W crystal, which has both a flat W(110) and a vicinal, stepped W(110) [W(320)] surface. This procedure reduces uncertainties in the quantitative description of peaks in the spectra from W(320). Various analyses, including nonlinear least-squares curve fitting, show that the average surface core-level shift (SCS) for W(320) is only ∼-140 meV, compared to -310 meV for W(110) and that, at a maximum, only two of five terrace rows are isoelectronic to W(110) surface atoms. The absence of a large SCS for the step-edge atoms contradicts earlier interpretations of …

Surface Core-Level Shifts Of Ta(110) And W(110) Vs. Alkali-Atom Coverage: Implications For Thealkali-Substrate Interaction, A. B. Andrews, D. Mark Riffe, G. K. Wertheim

All Physics Faculty Publications

The change in the average surface-atom core-level shift (SCS) produced by submonolayer coverages of alkali adsorbates is quite small for both Ta(110) and W(110), less than 45 meV in magnitude. The small change of the measured SCS’s as a function of coverage decisively supports the covalent-bonding picture of alkali adsorption proposed by Ishida and Terakura.

The Decomposition Of Calcium Tungstate And Synthetic Scheelite With Hydrochloric Acid, Robert R. Beebe

Bachelors Theses and Reports, 1928 - 1970

The decomposition of scheelite with hydrochloric acid was studied under conditions of variable acid concentration, time and temperature. The reactions were traced by weigh­ing material untransformed and, in some cases, by analyzing the transformation products.

The Benefication Of A Low-Grade, Montana Scheelite Ore, Walter G. Parker

Bachelors Theses and Reports, 1928 - 1970

The increasing importance of tungsten as an industrial metal and the recent discoveries of extensive deposits of low-grade tungsten ores in Montana led to the investigation which is reported in this paper. The purpose of this investigation was to determine if a saleable concentrate could be obtained from one of these low-grade, Montana scheelite ores.

Flotation Of Huebnerite, Henry Albright

Bachelors Theses and Reports, 1928 - 1970

The development of suitable beneficiation processes for treating domestic low-grade tungsten ores is a problem now facing the mineral industry. While we are now consuming more tungsten than normally because of the defense program, we are no longer able to import ores from the world's principal source, China. The problem then, is to increase our domestic production so as to ac­quire a greater degree of self-sufficiency.

The Birdie Mine Tungsten Deposit Butte Mining District, Silverbow County, Montana, Bernard A. Fahm

Bachelors Theses and Reports, 1928 - 1970

The importance of tungsten has encouraged the search for minerals of this metal, and consequently new deposits have been discovered, and known deposits have been re-examined. Western Montana has rather widespread deposits if low-grade types are also considered. Many deposits were known long ago, but abandoned because the use of tungsten was still in its beginning stage and therefore little attention was given to this type of mineral.