Dissertations / Theses on the topic 'Hydridic earth'
To see the other types of publications on this topic, follow the link: Hydridic earth.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 23 dissertations / theses for your research on the topic 'Hydridic earth.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Verbraeken, Maarten Christiaan. "Doped alkaline earth (nitride) hydrides." Thesis, St Andrews, 2009. http://hdl.handle.net/10023/714.
Full text
2
Treuil-Dussouet, Félix. "Photoconductivity in rare earth metal-oxy-hydrides." Thesis, Uppsala universitet, Materialteori, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-416695.
Full textAbstract:
In this project the evolution of resistivity under light exposition in materials like rare earth metal-oxy-hydrides is studied. These materials observe a decrease of the resistance when exposed under the light of a 19,5 W power lamp, and slowly tend to return to their initial resistance. After having developed a resistance measurement setup, the photoconductivity of different samples (Gd, YHO) was measured in function of the oxygen concentration and in different conditions such as the face of illumination.
3
Osterwalder, Jürg. "On the electronic structure of the light rare earth hydrides /." [S.l.] : [s.n.], 1985. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=7766.
Full text
4
Kazi, Suraya. "Electric Transport of Rare-earth Metal Oxy-hydride Thin Films." Thesis, Uppsala universitet, Materialfysik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-440954.
Full textAbstract:
In this project, I investigate the photoconductivenature of photochromic rare-earth metal oxy hydrides (REMHO). Such materials have received increasingscientific attention since they show a color-neutralphotochromic effect that can be applied, e.g., in smartwindows or chromogenic devices. Photochromicmaterials reversibly turn opaque from transparentunder illumination with light of optical wavelength. Inrecent studies it was found that these materials alsoshow an instant decrease in resistivity whenilluminated which can be used in optical sensors. Tounderstand the nature of this photoconductive effect,I grew yttrium oxy hydride thin films by reactivemagnetron sputtering. I measured the resistivity forillumination from front and substrate side, opticaltransmission and compositions of the samples andrelated the results to photoconductivity. I show thatphotoconductivity is a bulk effect and not directlyrelated to photochromism. Samples that almost lostphotochromism due to aging, still show strongphotoconductivity. Moreover, it was observed that theresistance increased faster during bleaching for frontillumination than for back illumination.
5
Kramer, Mathias. "Cationic alkyl and hydride complexes of the rare earth metals." Aachen Shaker, 2009. http://d-nb.info/998740497/04.
Full text
6
Pianalto, Frederick Scott 1961. "Laser spectroscopy of strontium-sulfide and alkaline earth monoborohydrides." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276739.
Full textAbstract:
Three gas phase alkaline earth molecules were analyzed using dye laser spectroscopy. The A¹Σ⁺ - X¹Σ⁺ transition of gas phase SrS was studied with high resolution techniques. The 0-0, 0-1, 1-1, 2-1, 3-0, 3-2, 4-1, 5-1, and 5-2 bands were rotationally analyzed and spectroscopic constants were determined. The A¹Σ⁺ state was extensively perturbed. Ground state (X¹Σ⁺) constants derived from the analysis of the nine vibrational levels include: ωₑ = 388.2643 cm⁻¹, Bₑ = 0.1208034(33) cm⁻¹, and rₑ = 2.439687(14) Å. Excited state (A¹Σ⁺) constants determined include: Tₑ = 13932.7068(10) cm⁻¹, ωₑ = 339.1454(20) cm⁻¹, Bₑ = 0.1139895(38) cm⁻¹, and rₑ = 2.511601(17) Å. The spectra of calcium and strontium borohydrides were observed using low resolution laser spectroscopy. The spectra were assigned to the òA₁ - Ẋ²A₁ and Ḃ²E - Ẋ²A₁ transitions of CaBH₄ and SrBH₄. The vibrational frequencies of the metal-ligand stretch determined for CaBH₄ were 457 cm⁻¹ (Ẋ²A₁), 473 cm⁻¹ (Ā²A₁), and 465 cm⁻¹ (Ḃ²E). The corresponding SrBH4 frequencies were 399 cm⁻¹, 420 cm⁻¹, and 421 cm⁻¹.
7
Aðalsteinsson, Sigurbjörn Már. "Study of rare-earth oxy-hydrides as candidates for photochromic materials." Thesis, Uppsala universitet, Tillämpad kärnfysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-396533.
Full text
8
Kramer, Mathias [Verfasser]. "Cationic Alkyl and Hydride Complexes of the Rare-Earth Metals / Mathias Kramer." Aachen : Shaker, 2009. http://d-nb.info/1161300929/34.
Full text
9
Sobaczynski, Adam [Verfasser], and Rhett [Akademischer Betreuer] Kempe. "Alkane Elimination Reactions between Transition Metal Hydrides and Rare-Earth Alkyls / Adam Sobaczynski. Betreuer: Rhett Kempe." Bayreuth : Universität Bayreuth, 2014. http://d-nb.info/1060010151/34.
Full text
10
Ekvall, Katrin. "Time resolved laser spectroscopy : non-linear polarisation studies in condensed phase and lifetime studies of alkaline earth hydrides /." Stockholm, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3063.
Full text
11
Aðalsteinsson, Sigurbjörn Már. "A study of the photochromic effect in oxygen containing rare-earth metal hydride thin films and multilayer structures." Thesis, Uppsala universitet, Tillämpad kärnfysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-418111.
Full textAbstract:
In this work, we have studied the photochromic response of several oxygen containing rare-earth hydride thin films (REHO, RE = Y, Nd, Gd, and Dy). Their chemical composition was characterized by an iterative multi-method approach based on ion beams, while the photochromic effect was measured by means of optical spectrometry. We report photochromic responses for YHO, NdHO, GdHO and DyHO of several thicknesses but averaged chemical compositions described by the formula REH2-δOδ; in the range of 0.45 < δ < 1.5 (δ being the [O]/[RE] ratio). Possible side-effects of the ambient conditions on the photochromic effect in YHO thin films were investigated by comparing the optical properties (photochromic response and bleaching) of YHO films capped with two different diffusion barrier layers (Al2O3 and Si3N4) to their respective uncapped sample. The ambient atmosphere was found to play no significant role in the photochromic effect. In sequence, identical YHO thin films were prepared on three different (transparent) substrates (i.e., soda lime glass, CaF2, and Al2O3 as buffer layer). The effect of substrate induced stress in the YHO thin films was investigated in details and no significant correlation between the substrate and photochromic effect was observed. Finally, isotope labeling in double layers of YHO and YDO was done to investigate possible diffusion of hydrogen/deuterium within the REHO layers. No diffusion of hydrogen/deuterium could be observed in the double layered structure during a one-week period and one illumination/bleaching cycle.
12
ZARPELON, LIA M. "Estudo das características eletroquímicas e microestruturais de eletrodos de hidreto metálico à base de LaNi com adições de elementos de liga." reponame:Repositório Institucional do IPEN, 2016. http://repositorio.ipen.br:8080/xmlui/handle/123456789/27133.
Full textAbstract:
Submitted by Mery Piedad Zamudio Igami (mery@ipen.br) on 2017-03-10T15:20:01Z
No. of bitstreams: 1
22060.pdf: 3959215 bytes, checksum: 0a58b276270c30e02d2f6935bafba229 (MD5)Made available in DSpace on 2017-03-10T15:20:01Z (GMT). No. of bitstreams: 1 22060.pdf: 3959215 bytes, checksum: 0a58b276270c30e02d2f6935bafba229 (MD5)
Neste trabalho avaliou-se a ação positiva da substituição de lantânio por praseodímio e de lantânio por magnésio na performance eletroquímica de eletrodos de ligas de armazenamento de hidrogênio em estado bruto de fusão e com tratamento térmico. O La foi substituído por Mg nas ligas La0,7-xMgxPr0,3Al0,3Mn0,4Co0,5Ni3,8 (x=0,0-0,7) e por Pr nas ligas La0,7-yPryMg0,3Al0,3Mn0,4Co0,5Ni3,8 (y=0,0-0,7). Os parâmetros eletroquímicos analisados foram ativação, capacidade de descarga, retenção da capacidade de descarga, autodescarga e alta taxa de descarga. As ligas apresentaram comportamento passivo em relação à corrosão. As análises por MEV/EDS e por DRX com refinamento por Rietveld revelaram a presença majoritária de fases similares às fases LaNi5, PrNi5, LaMg2Ni9 e PrMg2Ni9 em função das composições das ligas estudadas. Os parâmetros de rede e os volumes da célula unitária das fases diminuíram com a substituição crescente de La por Mg e de La por Pr. As capacidades de descarga máxima decresceram com a substituição crescente de La por Mg e de La por Pr, acompanhando o decréscimo da abundância da fase similar à fase LaNi5 e o aumento da abundância da fase similar à fase LaMg2Ni9. Comparativamente, menores taxas de autodescarga e maior estabilidade cíclica foram observadas para o eletrodo da liga na condição x=0,1, ao passo que o eletrodo da liga na condição y=0,0 apresentou maiores valores de alta taxa de descarga, indicando melhor performance cinética.
Tese (Doutorado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
13
Santoru, Antonio [Verfasser]. "Insights into the structure and reaction mechanism of alkali and alkaline-earth metal amide-metal hydride composite systems for hydrogen storage / Antonio Santoru." Hamburg : Helmut-Schmidt-Universität, Bibliothek, 2018. http://d-nb.info/1162510706/34.
Full text
14
CASINI, JULIO C. S. "Hidrogenação de ligas à base de terras raras para fabricação de eletrodos negativos de bateriais de níquel-hidreto metálico." reponame:Repositório Institucional do IPEN, 2011. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9958.
Full textAbstract:
Made available in DSpace on 2014-10-09T12:33:14Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:06:12Z (GMT). No. of bitstreams: 0
Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
15
Laou, Lamyaa. "Evaluation du comportement mécanique sous sollicitations thermohydriques d'un mur multimatériaux (bois, terre crue, liants minéraux) lors de sa construction et de son utilisation." Thesis, Limoges, 2017. http://www.theses.fr/2017LIMO0066/document.
Full textAbstract:
Les problèmes climatiques planétaires nous poussent à concevoir des systèmes constructifs à faible consommation d’énergie. L’utilisation des murs constitués d’écomatériaux (ossature bois avec un remplissage de brique de terre crue et assemblage parmortier minéral) apparaît comme une solution alternative intéressante et conforme aux objectifs en matière de développement durable. Dans une démarche de conception de ce type de système constructif, un outil de modélisation thermo-hydro-mécanique a été développé. Il vise d’une part à prédire la capacité de la paroi à réguler les conditions hygrothermiques ambiantes lors des alternances jour/nuit en fonction des différentes stratégies de ventilation, et d’autre part à identifier les différents scénarios décrits en termes de température et d’humidité pouvant induire l’apparition de fissures dans la paroi, aussi bien en phase de construction qu’en conditions de service. La rareté des travaux réalisés sur les propriétés de la terre crue nous a poussés à développer une campagne expérimentale multidisciplinaire pour caractériser les propriétés thermiques, hydriques et mécaniques sous différents états hydriques. Ces propriétés alimentent le modèle, dont les adaptations nécessaires sont présentées. Les résultats portent à la fois sur l’impact sur le confort hygrothermique et sur l’effet des variations hydriques sur la durabilité mécanique de la paroiGlobal climate problems push us to design energy-saving constructive systems. The use of walls made of eco-materials (wooden frame with a filling of brick of raw earth and assembled by mineral mortar) appears as an interesting alternative solution being in linewith the objectives in terms of sustainable development. In order to use a numerical simulation approach to this type of constructive system, a thermo-hydro-mechanical modeling tool was developed. On the one hand, it aims to predict the wall's ability to regulate the ambient hygrothermal conditions during day / night alternations according to the different ventilation assumptions and, on the other hand, to identify the various scenarios described in terms of temperature which can induce the appearance of cracks in the wall, both during construction and operating conditions. The originality of the work carried out on the properties of the raw earth make us able to develop a multidisciplinary experimental campaign to characterize the thermal, hydric and mechanical properties under different humidity conditions. These properties feed the numerical model with the necessary adaptations presented. The results present both the impact on hygrothermal comfort and to the effect of humidity changes on the mechanical durability of the wall
16
GALEGO, EGUIBERTO. "Estudo de ligas e imás preparados pelo processo hidrogenação, desproporção, dessorção e recombinação (HDDR) a base de Pr-Fe-B com adição de dopantes e elementos de liga." reponame:Repositório Institucional do IPEN, 2008. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11611.
Full textAbstract:
Made available in DSpace on 2014-10-09T12:53:50Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T13:58:58Z (GMT). No. of bitstreams: 0
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
17
FERREIRA, ELINER A. "Estudo da hidrogenação para pulverização de ligas à base de terras raras com Nb para eletrodos de hidreto metálico." reponame:Repositório Institucional do IPEN, 2013. http://repositorio.ipen.br:8080/xmlui/handle/123456789/26390.
Full textAbstract:
Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-06-22T13:51:24Z
No. of bitstreams: 0Made available in DSpace on 2016-06-22T13:51:24Z (GMT). No. of bitstreams: 0
Tese (Doutorado em Tecnologia Nuclear)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
18
Zarpelon, Lia Maria Carlotti. "Estudo das características eletroquímicas e microestruturais de eletrodos de hidreto metálico à base de LaNi com adições de elementos de liga." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-19012017-092218/.
Full textAbstract:
Neste trabalho avaliou-se a ação positiva da substituição de lantânio por praseodímio e de lantânio por magnésio na performance eletroquímica de eletrodos de ligas de armazenamento de hidrogênio em estado bruto de fusão e com tratamento térmico. O La foi substituído por Mg nas ligas La0,7-xMgxPr0,3Al0,3Mn0,4Co0,5Ni3,8 (x=0,0-0,7) e por Pr nas ligas La0,7-yPryMg0,3Al0,3Mn0,4Co0,5Ni3,8 (y=0,0-0,7). Os parâmetros eletroquímicos analisados foram ativação, capacidade de descarga, retenção da capacidade de descarga, autodescarga e alta taxa de descarga. As ligas apresentaram comportamento passivo em relação à corrosão. As análises por MEV/EDS e por DRX com refinamento por Rietveld revelaram a presença majoritária de fases similares às fases LaNi5, PrNi5, LaMg2Ni9 e PrMg2Ni9 em função das composições das ligas estudadas. Os parâmetros de rede e os volumes da célula unitária das fases diminuíram com a substituição crescente de La por Mg e de La por Pr. As capacidades de descarga máxima decresceram com a substituição crescente de La por Mg e de La por Pr, acompanhando o decréscimo da abundância da fase similar à fase LaNi5 e o aumento da abundância da fase similar à fase LaMg2Ni9. Comparativamente, menores taxas de autodescarga e maior estabilidade cíclica foram observadas para o eletrodo da liga na condição x=0,1, ao passo que o eletrodo da liga na condição y=0,0 apresentou maiores valores de alta taxa de descarga, indicando melhor performance cinética.In this work, the positive action of the substitution of lanthanum by praseodymium and lanthanum by magnesium in the electrochemical performance of the as-cast and annealed hydrogen storage alloys electrodes had been evaluated. La was replaced by Mg in La0.7-xMgxPr0.3Al0.3Mn0.4Co0.5Ni3.8 (x=0.0-0.7) alloys and by Pr in La0.7-yPryMg0.3Al0.3Mn0.4Co0.5Ni3.8 (y=0.0-0.7) alloys. The electrochemical parameters analyzed were activation, discharge capacity, discharge capacity retention, self-discharge rate and high-rate dischargeability. The alloys showed a passive corrosion behavior. The analyses by SEM/EDS and XRD with Rietveld refinement revealed the majority presence of LaNi5, PrNi5, LaMg2Ni9 and PrMg2Ni9 similar reference phases depending on the compositions of the studied alloys. The lattice parameters and cell volumes of the component phases decreased with increasing substitution of La for Mg and with La for Pr. The maximum discharge capacity decreased with increasing substitution of La for Mg and with La for Pr, following the decrease in the abundance of LaNi5 similar phase and the increase in the abundance of to the LaMg2Ni9 similar phase. Lower self-discharge rates were observed for the alloy electrode when x=0.1, while higher high-rate dischargeability for the alloy electrode when y=0.0 indicated better kinetic performance, comparatively.
19
Tencé, Sophie Marie-Hélène. "Propriétés et structures d’hydrures et de composés magnétocaloriques à base de terres rares." Thesis, Bordeaux 1, 2009. http://www.theses.fr/2009BOR13834/document.
Full textAbstract:
Les structures magnétiques de deux familles de composés sont déterminées et discutées : (i) celles des hydrures RTXH (R = terre rare, T = métal de transition et X = Si, Ge) cristallisant dans la structure de type ZrCuSiAs et obtenus par insertion d’hydrogène dans les intermétalliques quadratiques de type CeFeSi. L’hydrogénation induit des transitions magnétiques variées engendrées par la compétition entre la dilatation anisotrope de la maille cristalline causée par l’absorption d’hydrogène et l’apparition de la liaison chimique R-H; (ii) celles des siliciures ternaires R6T1.67Si3 (R = Ce, Nd, Gd, Tb et T = Co, Ni) présentant des propriétés magnétocaloriques significatives autour de leur température de Curie, en particulier ceux à base de gadolinium Gd6T1.67Si3. Les composés à base de Ce, Nd et Tb présentent des comportements magnétiques originaux qui sont expliqués par la détermination de leurs structures magnétiques. La nature complexe de ces propriétés résulte en partie de la présence de deux sites magnétiques pour R et d’un désordre atomique de l’élément T dans la structure cristallographiqueMagnetic structures of two families of compounds are determined and discussed : (i) those of the hydrides RTXH (R = Rare earth, T = transition metal and X = Si, Ge) crystallizing in the ZrCuSiAs-type structure and obtained by hydrogen insertion in the intermetallics adopting the tetragonal CeFeSi-type structure. Hydrogenation induces various magnetic transitions governed by the competition between the anisotropic unit cell expansion linked to hydrogen absorption and the occurrence of the R-H chemical bonding ; (ii) those of the ternary silicides R6T1.67Si3 (R = Ce, Nd, Gd, Tb and T = Co, Ni) which show significant magnetocaloric properties around their Curie temperature, especially those based on gadolinium Gd6T1.67Si3. The compounds based on Ce, Nd and Tb present original magnetic behaviors which are explained by their magnetic structures determination. The origin of these complex properties results especially from the presence of two magnetic sites for R and from an atomic disorder of the T element in the crystallographic structure
20
Rauch, Michael S. "Main Group Metal Hydride, Alkyl and Fluoride Complexes: Towards CO2 Functionalization with Earth Abundant Metals." Thesis, 2019. https://doi.org/10.7916/d8-t4qw-ak42.
Full textAbstract:
As levels of carbon dioxide continue to increase in the atmosphere, it is appealing to consider the prospect of utilizing CO2 as a C1 building block for the synthesis of value-added organic chemicals. Such transformations offer potential to directly counteract environmental concerns, and could also enhance the recyclability of current materials. To meet this challenge, the development of metal catalysts capable of promoting the functionalization of carbon dioxide is necessary. Furthermore, there is great interest in employing main group metals for these transformations, particularly those metals that are earth-abundant, non-toxic and affordable. To address these needs and others, the research herein has been driven by the synthesis and characterization of main group metal hydride, alkyl and fluoride complexes with the ultimate aim of developing catalysts for CO2 functionalization.
Chapter 1 investigates the synthesis of magnesium, zinc and calcium complexes supported by the tris[(1-isopropylbenzimidazol-2-yl)dimethylsilyl)]methyl ligand, [TismPriBenz]. Most significantly, the magnesium carbatrane compound, [TismPriBenz]MgH, which possesses a terminal hydride ligand, has been synthesized and structurally characterized. The corresponding magnesium methyl derivative, [TismPriBenz]MgMe, was also prepared, and the reactivity of these compounds with respect to both metathesis and insertion is explored in great detail. The synthesis and characterization of the corresponding zinc hydride complex, [κ3 TismPriBenz]ZnH, is also described, as well as the preparation of a rare example of a monomeric calcium benzyl compound, [TismPriBenz]CaCH2Ph. Some reactivity of the zinc and calcium derivatives is also described.
In Chapter 2, the aforementioned magnesium and zinc compounds and their reactivity towards CO2 is described in detail. Systems comprised of [TismPriBenz]MH (M = Mg, Zn) and tris(pentafluorophenyl)borane are highly effective for the room temperature reduction of CO2 with R3SiH to afford sequentially the bis(silyl)acetal, H2C(OSiR3)2, and CH4 (R3SiH = PhSiH3, Et3SiH and Ph3SiH). Notably, the selectivity of the catalytic system may be controlled by the nature of the silane. Catalytic intermediates were isolated and structurally characterized, including an interesting magnesium formatoborate complex, which has helped elucidate an understanding of the mechanism of the catalysis. Most significantly, it was found that H2C(OSiPh3)2 can be prepared on a multi-gram scale as a crystalline solid and can be converted directly into formaldehyde (CH2O), which is an important industrial chemical. Thus, H2C(OSiPh3)2 can serve as a formaldehyde surrogate and its ability to provide a means to incorporate CH and CH2 moieties into organic molecules is described. Isotopologues of H2C(OSiPh3)2, namely D2C(OSiPh3)2, H213C(OSiPh3)2, and D213C(OSiPh3)2, may be synthesized from the appropriate combinations of (12C/13C)O2 and Ph3Si(H/D), thereby providing a direct and convenient means to use carbon dioxide as a source of isotopic labels in complex organic molecules.
In Chapter 3, details pertaining to other transformations catalyzed by [TismPriBenz]MgR (R = H, Me) are provided and their mechanisms are discussed. Notably, [TismPriBenz]MgR is a catalyst for hydrosilylation and hydroboration of styrene to afford exclusively the Markovnikov products, Ph(Me)C(H)SiH2Ph and Ph(Me)C(H)Bpin; the magnesium alkyl intermediate in the catalytic process, [TismPriBenz]MgCH(Me)Ph, has been isolated and structurally characterized, providing the first structural evidence for the insertion of an olefin into a magnesium hydride bond. Other catalytic transformations are described, including hydroboration of carbodiimides to form N-boryl formamidines and hydroboration of pyridine to provide N-boryl 1,4- and 1,2-dihydropyridines. Additionally, the ability for the magnesium hydride and methyl complexes to catalyze dehydrocoupling reactions is discussed. Finally, the ability for [TismPriBenz]MgMe to catalyze the isomerization of a terminal alkyne is reported.
Chapter 4 outlines the chemistry of magnesium and zinc compounds supported by a different scaffold, namely, the tris(3-tert-butyl-5-methylpyrazolyl)hydroborato, [TpBut,Me], ligand. The magnesium methyl compound, [TpBut,Me]MgMe, was used as a precursor to prepare [TpBut,Me]MgF via metathesis with Me3SnF, and is the first example of a structurally characterized monomeric magnesium fluoride complex. The reactivity of [TpBut,Me]MgF is described, including its ability to serve as a hydrogen bond and halogen bond acceptor, such that it forms adducts with indole and C6F5I. Corresponding zinc chemistry was studied, including interesting reactivity of [TpBut,Me]ZnH and [TpBut,Me]ZnF. Finally, new heterobimetallic compounds containing magnesium or zinc supported by the [TpBut,Me] ligand and tungsten were synthesized and structurally characterized.
21
Auer, Henry, Robin Guehne, Marko Bertmer, Sebastian Weber, Patrick Wenderoth, Thomas Christian Hansen, Jürgen Haase, and Holger Kohlmann. "Hydrides of Alkaline Earth–Tetrel (AeTt) Zintl Phases: Covalent Tt–H Bonds from Silicon to Tin." 2017. https://ul.qucosa.de/id/qucosa%3A33406.
Full textAbstract:
Zintl phases form hydrides either by incorporating hydride anions (interstitial hydrides) or by covalent bonding of H to the polyanion (polyanionic hydrides), which yields a variety of different compositions and bonding situations. Hydrides (deuterides) of SrGe, BaSi, and BaSn were prepared by hydrogenation (deuteration) of the CrB-type Zintl phases AeTt and characterized by laboratory X-ray, synchrotron, and neutron diffraction, NMR spectroscopy, and quantum-chemical calculations. SrGeD4/3–x and BaSnD4/3–x show condensed boatlike six-membered rings of Tt atoms, formed by joining three of the zigzag chains contained in the Zintl phase. These new polyanionic motifs are terminated by covalently bound H atoms with d(Ge–D) = 1.521(9) Å and d(Sn–D) = 1.858(8) Å. Additional hydride anions are located in Ae4 tetrahedra; thus, the features of both interstitial hydrides and polyanionic hydrides are represented. BaSiD2–x retains the zigzag Si chain as in the parent Zintl phase, but in the hydride (deuteride), it is terminated by H (D) atoms, thus forming a linear (SiD) chain with d(Si–D) = 1.641(5) Å.
22
Mašková, Silvie. "Struktura a magnetické vlastnosti sloučenin s f-elektrony a jejich hydridů." Doctoral thesis, 2013. http://www.nusl.cz/ntk/nusl-328732.
Full textAbstract:
Title: Structure and magnetic properties of f-electron compounds and their hydrides Author: Silvie Mašková Department: Deparment of Condensed Matter Physics Supervisor: Doc. RNDr. Ladislav Havela, CSc., Deparment of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Prague, The Czech Republic Abstract: Magnetic properties were studied in several types of actinide- and lanthanide-based ternary compounds. We have shown indirect that anisotropy of compressibility and thermal expansion can be related to the direction of magnetic moments at U-compounds with "soft" directions (where the closest U-U links are) perpendicular to the moments direction. Comparison of U and RE compounds of the 2-2-1 type indicates that contrary to U compounds, RE compounds can absorb much more hydrogen. The involvement of the f-states in metallic bond, which takes place at actinides and not in lanthanides, makes the U-based compounds apparently more stable against hydrogenation. Basic electronic properties were established for ζ -Pu19Os, which is a close analogy to β-Pu, and for its low-temperature variety η -Pu19Os. The results confirm that the volume is not the main parameter driving Pu properties, as β-Pu with intermediate volume is the most strongly correlated Pu phase. Keywords: uranium compounds,...
23
"First principles exploration of crystal structures and physical properties of silicon hydrides KSiH3 and K2SiH6, alkali and alkaline earth metal carbides, and II-V semiconductors ZnSb and ZnAs." Doctoral diss., 2013. http://hdl.handle.net/2286/R.I.18130.
Full textAbstract:
abstract: This dissertation is focused on material property exploration and analysis using computational quantum mechanics methods. Theoretical calculations were performed on the recently discovered hexahydride materials A2SiH6 (A=Rb, K) to calculate the lattice dynamics of the systems in order to check for structural stability, verify the experimental Raman and infrared spectrospcopy results, and obtain the theoretical free energies of formation. The electronic structure of the systems was calculated and the bonding and ionic properties of the systems were analyzed. The novel hexahydrides were compared to the important hydrogen storage material KSiH3. This showed that the hypervalent nature of the SiH62- ions reduced the Si-H bonding strength considerably. These hydrogen rich compounds could have promising energy applications as they link to alternative hydrogen fuel technology. The carbide systems Li-C (A=Li,Ca,Mg) were studied using \emph{ab initio} and evolutionary algorithms at high pressures. At ambient pressure Li2C2 and CaC2 are known to contain C22- dumbbell anions and CaC2 is polymorphic. At elevated pressure both CaC2 and Li2C2 display polymorphism. At ambient pressure the Mg-C system contains several experimentally known phases, however, all known phases are shown to be metastable with respect to the pure elements Mg and C. First principle investigation of the configurational space of these compounds via evolutionary algorithms results in a variety of metastable and unique structures. The binary compounds ZnSb and ZnAs are II-V electron-poor semiconductors with interesting thermoelectric properties. They contain rhomboid rings composed of Zn2Sb2 (Zn2As2) with multi-centered covalent bonds which are in turn covalently bonded to other rings via two-centered, two-electron bonds. Ionicity was explored via Bader charge analysis and it appears that the low ionicity that these materials display is a necessary condition of their multicentered bonding. Both compounds were found to have narrow, indirect band gaps with multi-valley valence and conduction bands; which are important characteristics for high thermopower in thermoelectric materials. Future work is needed to analyze the lattice properties of the II-V CdSb-type systems, especially in order to find the origin of the extremely low thermal conductivity that these systems display.Dissertation/Thesis
Ph.D. Physics 2013