Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 134 for “"Fe-Co"”.
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Isotropic nanocrystalline (Nd,Pr)(Fe,Co)B permanent magnets
… aufgrund von Oberflächen- und Grenzflächeneffekten, die verschieden von denen massiver oder mikrokristalliner Materialien sind. Diese Arbeit zeigt Ergebnisse einer systematischen Untersuchung der Beziehung zwischen Mikrostruktur und magnetischen Eigenschaften von isotropen nanokristallinen …
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Ultrafast electron dynamics in Fe(CO)5 and Cr(CO)6
In this thesis, the two prototype catalysts Fe(CO)₅ and Cr(CO)₆ are investigated with time-resolved photoelectron spectroscopy at a high harmonic setup. In both of these metal carbonyls, a UV photon can induce the dissociation of one or more ligands of the complex. The mechanism of the dissociation …
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Neuartige Synthese magnetischer Nanostrukturen: Metallcarbide und Metallnitride der Übergangsmetalle Fe/Co/Ni
… Eigenschaften gesucht werden muss. Eisencarbid (Fe3C) kann eine dieser Verbindungen sein. Dieses besitzt vergleichbare positive Eigenschaften wie Eisenoxid, jedoch viel bessere magnetische Eigenschaften, speziell eine höhere Sättigungsmagnetisierung. Bis jetzt wurde Fe3C hauptsächlich in …
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Microstruture & High Frequency Property of Fe- & Co- Based Nano-Grain Thin Films
… the electromagnetic properties that can control the high frequency permeability. In this research, the permeability measurement method at high frequency for soft magnetic thin films was investigated; some Fe- and Co-based magnetic thin films deposited by rf magnetron sputtering were …
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Structural and magnetic characterization of Nd-based Nd-Fe and Nd-Fe-Co-Al metastable alloys
… characterize a metastable hard magnetic phase referred to as "A1" in Nd-Fe alloys, which forms as a part of the fine eutectic depending on the composition and cooling rate. In order to define the range of composition for the formation of A1, Nd100-xFex (x = 20, 25, 40) alloys are cooled …
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Phase stability and the Portevin-Le Chatelier effect in Cr-Mn-Fe-Co-Ni High-Entropy Alloys
… a new class of metallic materials based on the combination of multiple principal elements, often with the intention to form a concentrated solid solution. It has been suggested that these solid solution phases could offer enhanced mechanical properties, due to fluctuations in their local atomic …
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Two dimensional magnetic surface compounds: The c(2x2) Mn-induced superstructures on the fcc-(001) surfaces of Cu, Fe, Co and Ni
… zu Rechnungen der Bandstruktur außerdem festgestellt werden, daß Teile des Minoritätsspinbandes besetzt werden. Die Fermioberfläche des c(2x2)MnCu/Cu(001) Systems wurde mittels Photoemission untersucht. Es konnte weiterhin gezeigt werden, daß Kupfer epitaktisch auf dieser Oberfläche …
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Germanium hydride derivatives of transition metal carbonyls
Compounds of the type Fe(CO)₄(GeR₃)₂ containing two different methylgermyl substituents have been prepared and characterised. The preparation was via the exchange reaction Fe(CO)₄(GeR₃)₂ + [Mn(CO)₅]⁻ → [Fe(CO)₄(GeR₃)]⁻ + Mn(CO)₅(GeR₃) [Fe(CO)₄(GeR₃)]⁻ + GeXR’₃ → Fe(CO)₄(GeR₃)(GeR’₃) The compounds …
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Synthesis and stabilities of mononuclear iron (II) dicarbonyls derived from neutral NNS ligands : structural models of the apo-active site of mono-iron (Hmd) hydrogenase
… and characterization of iron dicarbonyl complexes derived from tridentate ortho-substituted Schiff base pyridine/thioether ligands ([subscript R]NNS) and (Fe(CO)₄(Br)₂). Two general synthetic routes are reported for the isolation of such iron carbonyls. First, metalation of [subscript …
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Catalytic and magnetic properties of nanostructured materials generated by ultrasound
High intensive ultrasound is a new and effective technique to generate nanostructured materials. The synthesis, characterization, and properties of three kinds of nanostructured materials produced sonochemically will be discussed in this thesis. Silica supported iron catalysts have been generated …
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Aspects of group 14 element - transition metal cluster chemistry
The synthesis of Sn[Fe₂(CO)₈]₂ from the SnCl₄/[Fe(CO)₄]²⁻ and SnCl₄/[Fe₂(CO)₈]²⁻ systems has been investigated. The reaction of SnCl₄ with the product mixture obtained by Na/amalgam reduction of Fe(CO)₅ provided the optimum yield (64% based on Sn). E[Co₂(CO)₇]₂ (E = Si, Ge), (CO)₄CoECo₃(CO)₉ (E = …
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Chemistry of Ruthenium and Rhodium Eta(4)-Thiophene Complexes
… (OTf)$\sb2$ (1d) with Cp$\sb2$Co produces (arene)Ru($\eta\sp4$-C$\sb4$R$\sb4$S) (2a-d). 2d is unstable $>-20\sp\circ$C. It reacts with Fe(CO)$\sb5$ in the presence of Me$\sb3$NO to yield the thermally stable $(\eta\sp5$-$\rm C\sb4Me\sb4S)Ru(\eta\sp4{:}\eta\sp1$-$\rm …
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Structure and bonding: The synthesis and characterization of heteronuclear clusters
… with methanolic solutions of KOH and $\rm Fe(CO)\sb5$ produces the isoelectronic clusters ($\rm HAs\{Fe(CO)\sb4\}\sb3\rbrack\sp{2-}, \lbrack Te\{Fe(CO)\sb4\}\sb3\rbrack\sp{2-}$, and $\rm \lbrack Se\{Fe(CO)\sb4\}\sb3\rbrack\sp{2-}$. The selenium cluster, however, is unstable and rapidly …
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Studies on polygermanyl-transition metal (carbonyl) derivatives
The compounds Ge₂ H₅Mn(CO)₅, Ge₂H₅Co(CO)₄ (Ge₂H₅)₂Fe(CO)₄, Ge₃H₇Mn(CO)₅, [GeH₂Mn(CO)₅] ₂ and [GeH₂Co(CO)₄] ₂ have been prepared by alkali-halide elimination reactions between the appropriate polygermanyl halides and metal carbonyl anions. The characterisation by infrared, Raman, n.m.r. and mass …
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Hydrogen Production From Model Complexes of the [iron-Iron]- and [nickel-Iron]-Hydrogenase Active Sites
Unlike the [FeFe]-hydrogenases, model complexes for the [NiFe]-hydrogenases were unknown prior to the crystal structure in 1996. However, most synthetic efforts focused on structural models for the active site, and neglected the catalytically imperative hydride ligand. Thus, we sought a nickel-iron …
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Electrospray-friendly ligands for the mass spectral analysis of transition-metal complexes
The key aim of this project was to develop the concept of electrospray-friendly ligands as a new ionisation method for the analysis of neutral metal complexes by electrospray mass spectrometry (ESMS). This involved introducing active functional groups into traditional ligands which do not otherwise …
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New high nuclearity carbonyl clusters
… and the chemical, structural and spectroscopic characterization of a series of new Rhodium and Au-Fe carbonyl clusters. Most new high-nuclearity rhodium carbonyl clusters have been obtained by redox condensation of preformed rhodium clusters reacting with a species in a different oxidation …
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Synthetic, structural and molecular modelling studies of organoiron complexes of catalytic importance
… dicarbonyl pentaznethylcyclopentadienyl iron compounds, [(η⁵-C₅(CH₃)₅)Fe(CO)₂R], is the starting point for an investigation of these compounds and their relevance as models for catalytic reactions. The compounds have been synthesized by the reaction of Na[(η⁵-C₅(CH₃)₅)Fe(CO)₂] with the …
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Darstellung, Reaktivität und Struktur von Mono- und Di-Manganiophosphonium Salzen sowie Lewis-Säure-Base-Addukte von Ferraten mit metallorganischen Lewissäuren
… mit dem 17-VE-Komplexfragment Cp’Mn(CO)(NO) vorgestellt. Aus 1a,b lassen sich mit Ph2PH die Monomanganiophosphonium-Salze [{Cp'Mn(CO)(NO)}PPh2H] +X- (X = BF4 -, PF6 -) (2a,b) darstellen. Diese werden mit Hilfe von DABCO zum Monomanganiophosphan 3 deprotoniert, das allerdings so …
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