A new design AMTEC converter model was developed, and its effectiveness as a design tool was evaluated. To develop the model, requirements of the model were defined, several new design models were successively developed, and finally an optimal new design model was developed. The model was created within Sinda/Fluint, with its graphical interface, Thermal Desktop, a software package that can be used to conduct complex thermal and fluid analyses. Performance predictions were then correlated and compared with actual performance data from the Road Runner II AMTEC converter. Predicted performance results were within 10% of actual performance data for all operating conditions analyzed. This accuracy tended to increase within operating ranges that would be more likely encountered in AMTEC applications. Performance predictions and parametric design studies were then performed on a proposed new design converter model with a variety of annular condenser heights and with potassium as a working fluid to evaluate the effects of various design modifications. Results clearly indicated the effects of the converter design modifications on the converter's power and efficiency, thus simplifying the design optimization process. With the close correlation to actual data and the design information obtained from parametric studies, it was determined that the model could serve as an effective tool for the design of AMTEC converters.

A new design AMTEC converter model was developed, and its effectiveness as a design tool was evaluated. To develop the model, requirements of the model were defined, several new design models were successively developed, and finally an optimal new design model was developed. The model was created within Sinda/Fluint, with its graphical interface, Thermal Desktop, a software package that can be used to conduct complex thermal and fluid analyses. Performance predictions were then correlated and compared with actual performance data from the Road Runner II AMTEC converter. Predicted performance results were within 10% of actual performance data for all operating conditions analyzed. This accuracy tended to increase within operating ranges that would be more likely encountered in AMTEC applications. Performance predictions and parametric design studies were then performed on a proposed new design converter model with a variety of annular condenser heights and with potassium as a working fluid to evaluate the effects of various design modifications. Results clearly indicated the effects of the converter design modifications on the converter's power and efficiency, thus simplifying the design optimization process. With the close correlation to actual data and the design information obtained from parametric studies, it was determined that the model could serve as an effective tool for the design of AMTEC converters.

Philosophiae Doctor - PhD / Aqueous ion-intercalation batteries (AIB’s) have the potential to provide both high power for hybrid-electric transport, and low cost bulk energy storage for electric grid supply. However, a major setback to AIB development is the instability of suitable ionintercalation anode material in aqueous electrolyte. To counter this problem, the use of activated carbon (AC) (a supercapacitor anode) paired against the low cost ionintercalation cathode spinel LiMn2O4 (LMO) provides a stable alternative. This thesis comprises two novel areas of investigation concerning: (1) the development of the AC/LMO cell for high power applications, and (2) the introduction of PbSO4 as a high capacity alternative anode material paired against LMO for low cost bulk energy storage. The study on AC/LMO explores the electrode combination’s practical specific energy and power capability at high P/E (power to energy ratio) of 50:1 suitable for hybrid electric vehicle batteries. To study the relationship between electrode material loading density, active material performance, and current collector mass contribution, a specially designed cell was constructed for galvanic cycling of different thicknesses of electrode. Between a loading density range of 25 – 100 mg, ~50 mg of total active material between two 1 cm2 current collectors produced the highest 50:1 P/E ratio values of 4 Wh/kg and 200 W/kg, constituting a 4-fold reduction of the active material values of thin films at 50:1 P/E. The cycling potentials of the individual electrodes revealed that doublings of electrode film loading density increased the LMO electrode’s polarization and voltage drop to similar levels as doublings in applied current density. However, by increasing the charging voltage from 1.8 V to 2.2 V, 6 Wh/kg and 300 W/kg was obtainable with minimal loss of energy efficiency. Finally a large-format cell of a calculated 3 Ah capacity at 50:1 P/E was constructed and tested. The cell produced ~60% of the anticipated capacity due to a suspected high level of resistance in the electrode contact points. The overall conclusion to the study was that AC/LMO holds promise for high power applications, and that future use of higher rate capability forms of LMO offers a promising avenue for further research. v The second part of this thesis presents the development of a novel cell chemistry, PbSO4/LMO, that has yet to be reported elsewhere in existing literature. The cell uses aqueous pH 7, 1 M, Li2SO4 electrolyte, and forms an electrode coupling where the PbSO4 anode charge/discharge is analogous to that in Pb-acid batteries. The average discharge voltage of the cell was 1.4 V and formed a flat charge/discharge plateau. The use of a low cost carbon coating method to encapsulate PbSO4 microparticles had a marked improvement on cell performance, and compared to uncoated PbSO4 improved both rate capability and specific capacity of the material. The active materials of the carbon-coated PbSO4/LMO cell produced a specific energy 51.1 Wh/kg, which, if a 65% yield is possible for a practical cell format, equals 38.4 Wh/kg, which is 15 Wh/kg higher than AC/LMO bulk storage cells at 23 Wh/kg, but lower than Pb-acid batteries at ~25-50 Wh/kg. Interestingly, the specific capacity of PbSO4 was 76 mAh/g compared to 100 mAh/g in Pb-acid cells. The predicted cost of the cell, providing a 65% value of the active material specific energy for a practical cell can be realized, is on par with Pb-acid battery technology and, importantly, uses 2.3 × less Pb/kWh. The cycling stability achieved thus far is promising, but will require testing over comparable cycle life periods to commercial batteries, which could be anywhere between 5 – 15 years.

L’intercalation de métaux dans le graphite a été réalisée pour la première fois en 1926. Depuis cette découverte, de nombreux composés binaires et ternaires ont été synthétisés. Au cours de ce travail, la méthode solide-liquide en milieu alliage fondu à base d’alcalin a d’abord été utilisée afin d’intercaler l’or dans le graphite à l’aide du potassium. Puis, l’intercalation du calcium dans des matériaux B-C-N de structure graphitique a été réalisée par le biais du lithium. La diffraction des rayons X, l’analyse par faisceau d’ions, la microscopie électronique ainsi que les techniques spectroscopiques associées ont été mises en œuvre pour caractériser ces nouveaux composés. Dans le cas du système graphite-potassium-or, trois nouveaux composés ternaires de premier stade et de distances interplanaires très différentes (1311, 953 et 500 pm) ont pu être synthétisés. Le composé K1,3Au1,5C4 a été isolé de façon reproductible et présente selon l’axe c une séquence d’empilement K-Au-Au-Au-K pour l’insérat. L’étude du mécanisme d’intercalation menant à ce composé a mis en évidence un intermédiaire réactionnel de formule K1,6Au0,7C4 dont le feuillet inséré est tricouche. Le troisième composé, KAu0,7C4, constitué de deux couches mixtes or-potassium, s’est quant à lui révélé métastable. Parallèlement, l’intercalation d’un alliage Li-Ca dans le matériau B-C-N a été réalisée avec succès. L’analyse par faisceau d’ions de l’hôte a permis de doser sur un même échantillon la teneur en bore, carbone et azote, conduisant à une formule B2C5N. Les mesures effectuées sur le matériau intercalé montrent la préservation du réseau hôte et l’insertion de 0,6 atome de lithium par atome de calcium / Since the discovery in 1926 of the first graphite intercalation compounds containing alkali metals, numerous binary and ternary compounds have been synthesized. In this work, solid-liquid method in alkali metal based molten alloys has been employed to intercalate gold into graphite using potassium as an intercalation vector for opening the van der Waals’s gaps and decreasing the reaction temperature. Then, lithium has been used to assist the intercalation of calcium into B-C-N compounds. X-ray diffraction, ion beam analysis, electron microscopy and associated spectroscopy techniques have been performed to characterize the as-prepared compounds. In the case of graphite-potassium-gold system, three novel ternary first stage intercalation compounds with very different repeat distances (1311, 953 and 500 pm) have been synthesized. The K1.3Au1.5C4 compound, isolated in a reproducible fashion, presents a K-Au-Au-Au-K c-axis stacking sequence for the intercalated sheets. The study of its intercalation mechanism evidenced an intermediate product which chemical formula is K1.6Au0.7C4, with three-layered intercalated sheets. The third compound KAu0.7C4 is metastable and contains in each van der Waals‘s gap two successive layers containing a mixture of gold and potassium. Elsewhere, the intercalation of a Li-Ca alloy into B-C-N host material has been successfully carried out. The ion beam analysis of the pristine B-C-N lead to determine on a same sample the amount of boron, carbon and nitrogen with the corresponding B2C5N formula. The experiments realized on the intercalated compound showed the preservation of the host lattice and the intercalation of 0.6 lithium per calcium atom

No description available.

Alkali metal chloride melts are used to refine refractory metals and as a heat carrier for promising nuclear reactors. The oxygen content is a critical parameter for such systems. It determines technological process and the quality of obtained products. The work is devoted to the development of methods for the determination of oxygen in chloride melts. HORIBA EMGA-620W/C gas analyzer was used. The paper presents information on the choice of methods for determining oxygen in various oxygen-containing compounds of tungsten and molybdenum. An inert chamber has been developed and combined with a gas analyzer. This allowed to determine low oxygen contents in volatile matrices with high affinity for oxygen. / Системы хлоридных расплавов щелочных металлов применяются для рафинирования ряда тугоплавких металлов и в качестве теплоносителя в перспективных реакторах нового типа. Содержание кислорода в таких системах является критическим параметром, обуславливающим правильный ход технологического процесса и качество получаемой продукции. Работа посвящена разработки методики определения кислорода в хлоридных расплавах. Для измерений использовали газоанализатор HORIBA EMGA-620W/C. В работе представлены сведения о выборе способов определения кислорода в различных кислородсодержащих соединениях вольфрама и молибдена. Разработана и совмещена с газоанализатором инертная камера, позволяющая проводить определения низких содержаний кислорода в относительно летучих матрицах, в том числе с макрокомпонентами, имеющими высокое сродство к кислороду. Выбраны оптимальные условия проведения измерений.

In dieser Arbeit wird eine, zeitabhängige, nicht störungstheoretische numerische Methode entwickelt, welche Ionisation und Anregung von Atomen oder Molekülen in Stößen mit entweder PB oder P beschreibt und auf der impact-parameter Methode basiert. Es wird eine spektrale close-coupling Methode verwendet, um die zeitabhängige Schrödinger-Gleichung zu lösen, in welcher die Wellenfunktion in (effektive) Ein- oder Zwei-Elektronen-Eigenzustände des Targets entwickelt wird. Dies beinhaltet auch eine erstmalige volle Zwei-Elektronen-Beschreibung von H2 in PB-Stößen. Rechnungen werden für PB-Stöße mit H, H2+ und H2 sowie He und den Alkaliatomen Li, Na, K und Rb durchgeführt. Daten für P-Stöße werden für H2 und die Alkaliatomen Li, Na und K erzielt. Die Methode wird durch einen detaillierten Vergleich der erhaltenen Ergebnisse für P-Stöße und für PB + He mit Literaturdaten verifiziert. Andererseits ergänzen die totalen und differentiellen Wirkungsquerschnitte für Ionisation und Anregung der Targets in PB-Stößen die spärliche Literatur. Sowohl die Resultate für verschiedene Targets als auch für PB- und P-Stöße werden miteinander verglichen. Ein Schwerpunkt dieser Arbeit liegt auf der Untersuchung von PB + H2, welche die Abhängigkeit der Wirkungsquerschnitte vom Kernabstand und von der relativen Ausrichtung der molekularen Achse beinhaltet. Weiterhin werden Ergebnisse mit Ein-Elektronen-Modellpotentialen erzielt und mit der vollen Zwei-Elektronen-Beschreibung von H2 verglichen. Außerdem werden Energieverluste in PB-Stößen bestimmt. / In this work a nonperturbative, time-dependent numerical approach is developed which describes ionization and excitation of atoms or molecules by either PB or P impact based on the impact-parameter method. A spectral close-coupling method is employed for solving the time-dependent Schrödinger equation in which the scattering wave function is expanded in (effective) one- or two-electron eigenstates of the target. This includes for the first time a full two-electron, two-center description of the H2 molecule in PB collisions. The radial part of the one-electron eigenstates is expanded in B splines while the two-electron basis is obtained with a configuration-interaction approach. Calculations are performed for PB collisions with H, H2+, and H2 as well as with He and alkali-metal atoms Li, Na, K, and Rb. Additionally, data are obtained for P collisions with H2, Li, Na, and K. The developed method is tested and validated by detailed comparison of the present findings for P impacts and for PB + He collisions with literature data. On the other hand, total and differential cross sections for ionization and excitation of the targets by PB impact complement the sparse literature data of this kind. Results gained from different targets as well as from PB and P impact are compared with each other and assessed. Furthermore, results obtained with one-electron model potentials are compared to the full two-electron description of H2. Finally, stopping powers for PB impacts are determined.

In vorliegender Arbeit wurden Synthese, Kristallstruktur und thermisches Verhalten von sauren und basischen Monofluorophosphate untersucht. Es wurden Salze mit Alkalimetall- und N-haltigen Kationen dargestellt und kristallographisch charakterisiert. Die Strukturen dieser Verbindungen wurden dann mit denen der isoelektronischen Hydrogensulfate verglichen. Mit Hilfe des Kationenaustausches und der Gefriertrocknung konnte ein erfolgreicher Syntheseweg fuer diese Verbindungen entwickelt werden. Die Gefriertrocknung hinderte die Abspaltung von HF und Kondensation des Phosphats und ermöglichte die Isolierung der Rohprodukte. Auf diesem Weg gelang die Darstellung der reinen Verbindungen in höherer Ausbeute, so daß es möglich wurde, die Substanzen mit unterschiedlichen Methoden zu untersuchen. Hergestellt und kristallographisch untersucht wurden folgende Verbindungen: - Hydrogenmonofluorophosphate mit × Alkalimetallkationen: Na, K, Rb, Cs × N-haltigen Kationen: NH4, NMe4, NH2Et2, NHEt3, [C(NH2)3], {HOC[NH(CH3)]2}, [H2N(CH2CH2)NH2], - basische Monofluorophosphate: Na2PO3F·10H2O und [C(NH2)3]2PO3F - gemischte Salze: Cs3(NH4)2(HPO3F)3(PO3F)2 und Na5[NMe4](PO3F)3·18H2O. Die Kristallstrukturen zeigen eine Vielzahl an Strukturtypen, definiert durch die Verknüpfung der verzerrten HPO3F Tetraeder über kurze O-H···O Wasserstoffbrückenbindungen zu Ketten, Dimere oder Tetramere. Diese sind ihrerseits über längere N-H···O und Ow-H···O Wasserstoffbrückenbindungen verknüpft. Kompliziertere Strukturmotive sind in den Strukturen der basischen Monofluorophosphate und der gemischten Salze zu finden. Allgemein werden nur Wasserstoffbrückenbindungen des Typs N-H...O und O-H...O gefunden, dagegen werden keine N-H···F Bindungen in den Strukturen beobachtet. Auch ist mehrheitlich keine Isotypie zwischen sauren und basischen Monofluorophosphaten einerseits und den entsprechenden Sulfaten andererseits zu finden. Isotyp sind nur die Strukturen [NMe4]HPO3F·H2O mit [NMe4]HSO4·H2O und Na2PO3F·10H2O mit Na2SO4·10H2O. Interessanterweise wurden genau in einer dieser isotypen Strukturen, nämlich der des Na2PO3F×10H2O, als Ausnahme zwei O-H···F Bindungen gefunden. Die O···F Abstände liegen im Bereich der Abstände der Ow···O Bindungen in der Struktur. Eine Erklärung für das seltene Auftreten von H-Brücken mit Fluor als Akzeptor ist eine fast vollständige Valenz des Fluors durch seine Bindung zum Phosphor. Mehrere Strukturen widerspiegeln diese Tatsache mit der Orientierung der P-F Bindung. Die Bindung wird nach inerten Stellen, wo kein Metall- oder Wasserstoffatom in der Struktur vorhanden ist, ausgerichtet, um ein weiteres Binden des Fluors (Metallkoordination, Wasserstoffbrückenbindung) zu vermeiden. Weiterhin wurde das thermische Verhalten der Verbindungen NaHPO3F, NaHPO3F·2.5H2O, CsHPO3F und [NHEt3]HPO3F untersucht. Dies erfolgte mit dem Ziel, Information über mögliche Phasenübergänge und die unterschiedlichen Zersetzungstypen zu bekommen. Sowohl der Kation wie auch die Anwesenheit von Kristallwasser haben Einfluß auf den thermischen Abbau. Die Na-Verbindungen zeigen eine Zersetzung über mehrere Schritte, die zu unterschiedlichen Endprodukten führt (Na3P3O9 für NaHPO3F und (NaPO3)n für das Hydrat). Im Vergleich dazu zersetzt sich CsHPO3F nach dem Schmelzen direkt zum Endprodukt, ohne stabile Zwischenprodukte zu bilden. Ähnlich verläuft der thermische Abbau der [NHEt3] Verbindung, die sich allerdings mit einem Masseverlust von 92,27%, also ohne Bildung eines signifikanten Endproduktes, vollständig zersetzt. Während des thermischen Abbaus wurde die Freisetzung von HF und H2O bei allen Verbindungen beobachtet, die sich aber bezüglich der Zersetzungstemperatur und -menge zwischen den Substanzen unterscheiden. Es wurden keine Phasenübergänge erster Ordnung beobachtet. Dies war insbesondere für CsHPO3F überraschend, da das isoelektronische Hydrogensulfat mehrere Phasenübergänge aufweist [2]. Das Ausbleiben von Phasenübergängen allgemein und auch für CsHPO3F wird folgendermassen erklärt. Während das Sulfat Bindungsmöglichkeiten an allen vier Ecken des SO4-Tetraeders hat, besitzt der (H)PO3F-Tetraeder nur eine begrenzte Flexibilität wegen der Anwesenheit von Fluor an einer Ecke. Fluor bevorzugt eine "isolierte" Position am Phosphor. Anhand der vorliegenden Ergebnisse kann die Schlußfolgerung gezogen werden, daß Fluor auf Grund seiner niedrigeren Valenz im Vergleich zu Sauerstoff andere strukturelle und funktionelle Charakteristika aufweist. Die Valenzunterschiede zwischen Sauerstoff und Fluor haben einen starken Einfluß auf das Wasserstoffbrückenbindungssystem in den Kristallstrukturen der Hydrogenmonofluorophosphate und folglich auf die "Nicht-Isotypie" zu den Hydrogensulfaten. / In this thesis, the crystal structures and thermal behavior of hydrogen monofluorophosphates and basic monofluorophosphates with alkali metal and N-containing cations were studied. A comparison to the analogous hydrogen sulfates showed interesting structural variations and differences in thermal behavior. Synthesis of the studied monofluorophosphates involved cation exchange and freeze drying. Freeze drying enabled the isolation of raw products by avoiding the escape of HF and consequent phosphate condensation. This method of preparation led to the synthesis of the hydrogen monofluorophosphates with the following cations: - the alkali metals: Na+, K+, Rb+, and Cs+, - N-containing cations: NH4+, [NMe4]+, [NH2Et2]+, [NHEt3]+, [C(NH2)3]+, {HOC[NH(CH3)]2}+, and [H2N(CH2CH2)NH2]2+, and the basic monofluorophoshates, Na2PO3F·10H2O and [C(NH2)3]2PO3F. The following mixed salts were also obtained with partial cation exchange: - Cs3(NH4)2(HPO3F)3(PO3F)2 - Na5[NMe4](PO3F)3·18H2O. In the crystal structures, the HPO3F tetrahedra were hydrogen-bonded to chains, dimers, and tetramers in the structures of the hydrogen monofluorophosphates. Extensive hydrogen bonding in the basic monofluorophosphates due to high amounts of crystal water led to more complicated structural motifs. Limitations on the bonding of fluorine were observed in each of the structures, whether it be metal coordination or hydrogen bonding. The valency of fluorine is filled by its bond to phosphorus and thus, generally, the fluorine atom does not participate in additional bonds. This explains why, for the most part, the hydrogen monofluorophosphates are not isostructural with the hydrogen sulfates. Only three atoms of the tetrahedron instead of four atoms are available for hydrogen bonding, which influences the crystal structure. This was further confirmed by the comparison of the decahydrates, Na2PO3F×10H2O and Na2SO4×10H2O, which are consequently isostructural based on two O-H×××F bonds formed in Na2PO3F·10H2O. These were the only hydrogen bonds found that involved fluorine as an hydrogen acceptor or donor. The investigations on the thermal behavior of NaHPO3F, NaHPO3F·2.5H2O, CsHPO3F, and [NHEt3]HPO3F found no first-order phase transitions. Stepwise decompositions were observed for the sodium salts, which was attributed to the formation of stable intermediates identified with simulated experiments. The Cs and [NHEt3] compounds demonstrated a direct decomposition postmelting. In general, the release of H2O from the melt occured at lower temperatures, while HF escaped at higher temperatures. The temperatures, at which this initially occured, and the first maximum observed were dependent on the cation and the presence of crystal water. The immediate decomposition of CsHPO3F after melting differs from that of the hydrogen sulfate, CsHSO4, which undergoes several phase transitions before decompositon. This suggests that the sulfate has more structural flexibility on the basis of the four oxygen corners of the tetrahedra. In comparison, the monofluorophosphate is limited in its bonding mobility due to the presence of fluorine on one of the tetrahedral vertices. Therefore, phase transitions are not observed prior to decomposition. It was concluded that fluorine functions differently in the crystal structures on the basis of its lower valency. Thus, the difference in valency between fluorine and oxygen affects the hydrogen bonding of the hydrogen monofluorophosphates and thus pervents the expected isotypy of the isoelectronic hydrogen monofluorophosphates and hydrogen sulfates.

No description available.