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Swaminathan, Narasimhan. "Stress-defect transport interactions in ionic solids." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/28273.
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Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2009.Committee Chair: Qu, Jianmin; Committee Member: Kohl,Paul A.; Committee Member: Liu, Meilin; Committee Member: McDowell, David L.; Committee Member: Zhu, Ting.
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Melle-Franco, Manuel. "Computer simulation of ionic solids of technological interest." Thesis, University of Kent, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327447.
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Zachariah, Manesh. "Electronic & ionic conduction & correlated dielectric relaxations in molecular solids." Doctoral thesis, Universitat Politècnica de Catalunya, 2016. http://hdl.handle.net/10803/404446.
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The study of crystalline materials has played a prominent role in solid state physics, whose basic theories were formulated for crystalline matter. However, disordered materials are more abundant in nature than crystalline ones, and, moreover, many practical applications use materials which are weakly or strongly disordered, such as molecular crystals, glasses, plastic crystals, liquids, polymers, or liquid crystals. In glasses, for example, the arrangement of the constituent atoms or molecules lacks any long-range order. From a fundamental viewpoint, we still lack an understanding of the properties of disordered materials and of the glass transition: understanding the many fascinating issues related with disorder requires in fact the use of concepts that are far from the well-known solid-state concepts associated with periodicity. From an applied perspective, the intense research in disordered solids is driven by the technological importance of these materials in daily life. From an electrical viewpoint, disordered solids can conduct electricity by transport of either electrons or ions. In the first case, disordered materials display lower electrical conductivity than their crystalline counterparts, due to localization of conduction electrons due to disorder, so that electron hopping is the main charge transport mechanism. On the other hand, the same disorder may allow the diffusion of ions through interstitial sites; the ionic conductivity of disordered materials is normally higher than the crystalline counterparts.
This thesis presents an experimental study of the conduction properties and molecular dynamics of molecular solids made of fullerene derivatives (C60Br6, C60(ONa)24) and of dinitrile molecules such as succinonitrile (C2H4(CN)2) and glutaronitrile (C3H6(CN)2). The studied materials display, depending on the case, mainly electronic, protonic, or ionic conduction. The thesis provides insight into the different possible types of charge conduction in organic molecular materials and on related physical processes such as space-charge relaxations.
In C60Br6 we observe n-type electronic conduction below room temperature and a non-trivial phase behavior. The temperature dependence of the dc conductivity of this organic semiconductor is in agreement with the variable-range hopping model. C60(ONa)24 has even richer phase behavior. It is synthesized as a polycrystalline hydrate, and can be obtained as pure material by heating to high temperature. We show that while the pure material is an n-type (electron) semiconductor, exposing it to humid atmosphere leads to a dramatic conductivity enhancement due to charge transport through the hydration layers, which is likely mediated by a proton exchange mechanism as in bulk water and ice. We also show that the dc conductivity of the hydrate is strongly temperature dependent across the dehydration process, and that both pure and hydrated forms display a conductivity-related dynamic process associated with accumulation of electrons at grain boundaries. The presence of water has strong impact on such frequency-dependent charge-accumulation dynamics.
We finally analyze the relaxation dynamics and the ionic conductivity of plastic-crystalline ionic conductors, in particular the plastic cocrystals of succinonitrile with glutaronitrile. In plastic crystals, the molecules occupy lattice sites but undergo free rotational motions about their centers of mass. We find that succinonitrile-glutaronitrile cocrystals are the first ever known plastic crystals to display a perfect correlation between the ion drift and the on-site reorientational dynamics. Doping the cocrystals with Li salts boosts the conductivity but breaks down this perfect correlation. This indicates that the rotation-drift correlation is only valid when charge transport is dominated by self-diffusion of molecular (dinitrile) ions, and that it is a consequence of the correlation between rotational and diffusional time scales.El estudio de los materiales cristalinos juega un papel destacado en la física del estado sólido. Sin embargo, los materiales desordenados son más abundantes en la naturaleza que los cristalinos y, además, muchas de las aplicaciones prácticas utilizan materiales que son débilmente o fuertemente desordenados, como vidrios, líquidos, cristales plásticos, cristales moleculares, polímeros, o cristales líquidos. Desde un punto de vista fundamental, aún carecemos de una comprensión de de los materiales desordenados y de la transición vítrea: la comprensión de las propiedades asociadas desorden requiere el uso de conceptos que se alejan de los aplicables al estado cristalino. Desde una perspectiva aplicada, la investigación en los sólidos desordenados está promovida por la importancia tecnológica de estos materiales en la vida cotidiana. Los sólidos desordenados pueden conducir electricidad por transporte de electrones o de iones. En el primer caso, los materiales desordenados muestran menor conductividad que sus respectivas fases cristalinas, debido a la localización de los electrones de conducción por la existencia de desorden, que da lugar a saltos de electrones como principal mecanismo de transporte de carga. Por otro lado, el mismo desorden puede permitir la difusión de iones a través de intersticios; la conductividad iónica de materiales desordenados es más alta que sus fases homólogas cristalinas. Esta tesis presenta un estudio experimental de la conducción eléctrica y de la dinámica molecular de sólidos moleculares formados por derivados de fullereno (C60Br6, C60(ONa)24) o por moléculas con dos grupos nitrilos (succinonitrila (C2H4(CN)2), glutaronitrila (C3H6 (CN)2)). Estos materiales presentan, según el caso, conducción electrónica, protónica, o iónica. La tesis analiza los diferentes tipos de conducción de carga en materiales moleculares así como los procesos físicos relacionados, tales como las relajaciones de carga espacial. En el material C60Br6 observamos conducción electrónica tipo n y un comportamiento de fase no trivial. La dependencia de la conductividad con la temperatura está de acuerdo con el modelo de salto de rango variable (VRH). El C60(ONa)24 tiene un comportamiento de fase aún más rico. Se sintetiza como un hidrato policristalino, y se puede obtener como material puro por calentamiento. Mientras que el material puro es un semiconductor de tipo n, su exposición a una atmósfera húmeda aumenta la conductividad de forma dramática debido al transporte de carga a través de las capas de hidratación, lo que probablemente se debe a un mecanismo de intercambio de protones como en el agua pura o en el hielo. La conductividad del hidrato depende fuertemente de la temperatura en el proceso de deshidratación. Ambas formas, pura e hidratada, muestran un proceso dinámico asociado a la acumulación de electrones en los límites de grano. La presencia de agua tiene un fuerte impacto en tal proceso. Por último se analizan la dinámica molecular y la conductividad iónica de cristales plásticos, en particular, de las aleaciones moleculares en fase plástica formadas entre la succinonitrila y la glutaronitrila. En las fases plásticas las moléculas ocupan los sitios cristalográficos de la red, pero se encuentran orientacionalmente desordenadas. Se demuestra que las aleaciones succinonitrila-glutaronitrila son los primeros cristales plásticos que se conocen en los que existe una correlación perfecta entre la corriente de iones y la dinámica reorientational de las moléculas en los sitios cristalográficos. El dopaje de las aleaciones con sales de Li aumenta la conductividad pero destruye la correlación anterior, lo que indica que la correlación sólo es válida cuando el transporte de carga está dominado por la difusión de iones moleculares. Tal correlación puede ser consecuencia de una correlación entre las escalas de tiempo de rotación y de difusión.
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Datta, Biswajit. "Exploration of miscellaneous interfaces of some ionic solids and ionic liquids Prevailing in various solvent systems by the process of psysicochemical contrivance." Thesis, University of North Bengal, 2017. http://ir.nbu.ac.in/handle/123456789/2673.
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Burgess, Kevin. "Solid-State Nuclear Magnetic Resonance of Exotic Quadrupolar Nuclei as a Direct Probe of Molecular Structure in Organic Ionic Solids." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/31971.
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In the past decade, the field of NMR spectroscopy has seen the emergence of ever more powerful superconducting magnets, which has opened the door for the observation of many traditionally challenging or non-receptive nuclei. In this dissertation, a variety of ionic solids with organic coordination environments are investigated using quadrupolar solid-state NMR experiments with an ultrahigh-field magnet (21.1 T). Two general research directions are presented including a 79/81Br solid-state NMR study of a series of 6 triphenylphosphonium bromides for which single-crystal X-ray structures are reported herein. A second research direction is also presented wherein alkaline-earth metal (25Mg, 43Ca, and 87Sr) solid-state NMR is used to characterize a systematic series of 16 aryl and alkyl carboxylates. In both studies, the quadrupolar nuclei studied are deemed “exotic” due to their unreceptive nature to NMR spectroscopic analysis including low natural abundances, large quadrupole moments, or low resonance frequencies. A variety of coordination modes to alkaline-earth metals, including N-atom coordination, are characterized herein for the first time using alkaline-earth metal solid-state NMR. In all cases, the electric field gradient (EFG) and chemical shift (CS) tensors are characterized and correlated to structural features such as interatomic distances measured from the crystal structure of the compound under study.
In all of the projects undertaken herein, the gauge-including projector-augmented-wave density functional theory (GIPAW DFT) method is used, which allows for the prediction and rationalization of the experimental EFG and CS tensor parameters based on the input crystal structure. In the case of 43Ca solid-state NMR experiments reported in this dissertation, a linear correlation between the calculated and experimental 43Ca quadrupolar coupling constants, CQ, is used as a calibration curve for GIPAW DFT calculations performed on the 18 structural models currently available for the vaterite polymorph of CaCO3. Vaterite cannot be fully characterized by X-ray diffraction alone; therefore an NMR crystallography protocol is used in order to identify the model that best accounts for 43Ca solid-state NMR experiments performed on vaterite. It is expected that the conclusions from this dissertation can be used for future studies involving structural refinement and elucidation of solid materials containing challenging quadrupolar nuclei.
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Swartz, Charles W. "First Principles Calculations for Liquids and Solids Using Maximally Localized Wannier Functions." Diss., Temple University Libraries, 2014. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/274283.
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PhysicsPh.D.
The field of condensed matter computational physics has seen an explosion of applicability over the last 50+ years. Since the very first calculations with ENIAC and MANIAC the field has continued to pushed the boundaries of what is possible; from the first large-scale molecular dynamics simulation, to the implementation of Density Functional Theory and large scale Car-Parrinello molecular dynamics, to million-core turbulence calculations by Standford. These milestones represent not only technological advances but theoretical breakthroughs and algorithmic improvements as well. The work in this thesis was completed in the hopes of furthering such advancement, even by a small fraction. Here we will focus mainly on the calculation of electronic and structural properties of solids and liquids, where we shall implement a wide range of novel approaches that are both computational efficient and physically enlightening. To this end we routinely will work with maximally localized Wannier functions (MLWFs) which have recently seen a revival in mainstream scientific literature. MLWFs present us with interesting opportunity to calculate a localized orbital within the planewave formalism of atomistic simulations. Such a localization will prove to be invaluable in the construction of layer-based superlattice models, linear scaling hybrid functional schemes and model quasiparticle calculations. In the first application of MLWF we will look at modeling functional piezoelectricity in superlattices. Based on the locality principle of insulating superlattices, we apply the method of Wu et al to the piezoelectric strains of individual layers under iifixed displacement field. For a superlattice of arbitrary stacking sequence an accurate model is acquired for predicting piezoelectricity. By applying the model in the superlattices where ferroelectric and antiferrodistortive modes are in competition, functional piezoelectricity can be achieved. A strong nonlinear effect is observed and can be further engineered in the PbTiO 3 /SrTiO 3 superlattice and an interface enhancement of piezoelectricity is found in the BaTiO 3 /CaTiO 3 superlattice. The second project will look at The ionization potential distributions of hydrated hydroxide and hydronium which are computed within a many-body approach for electron excitations using configurations generated by ab initio molecular dynamics. The experimental features are well reproduced and found to be closely related to the molecular excitations. In the stable configurations, the ionization potential is mainly perturbed by solvent water molecules within the first solvation shell. On the other hand, electron excitation is delocalized on both proton receiving and donating complex during proton transfer, which shifts the excitation energies and broadens the spectra for both hydrated ions. The third project represents a work in progress, where we also make use of the previous electron excitation theory applied to ab initio x-ray emission spectroscopy. In this case we make use of a novel method to include the ultrafast core-hole electron dynamics present in such situations. At present we have shown only strong qualitative agreement with experiment.
Temple University--Theses
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Mbogo, Francis Njagi. "Vibrational spectroscopy and latent symmetry effects in metal tricarbonyls and ionic solids : and dynamics of unusually H-bonded systems." Thesis, University of East Anglia, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304529.
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Shakhov, Alexander. "Structure-Dynamics Relationships in Complex Fluids and Disordered Porous Solids Assessed using NMR." Doctoral thesis, Universitätsbibliothek Leipzig, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-153105.
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A NMR study of the structure-dynamics relationships in heterogeneous materials is presented. In the first part, transport in soft-matter systems is studied using the pulsed field gradient NMR technique (PFG NMR). The molecular crowding effect in biological matter has been addressed using polymer solutions as model systems. By performing ensemble-based diffusion studies, the earlier obtained data on anomalous diffusion have been complemented. The transition to normal diffusion on a larger time scale has been shown. Taking advantages of the NMR approach, transport properties of microemulsions consisting of micellar colloids dissolved in liquid crystals have been investigated. The self-diffusivities measured under equilibrium conditions have shown weak correlations with microscopic ordering and macroscopic phase transitions occurring in the systems under study. The formation of micelles is shown to be decisive for macroscopic separation at the isotropic-nematic transition.
The second part of the thesis covers heterogeneous effects in diffusion for fluids in porous solids, as probed using a combination of NMR diffusometry and structure characterization methods. Ionic liquids have been investigated, revealing a complex behavior under confinement. The attempts to correlate the observed characteristics of the ionic liquids with their internal chemical structure were undertaken. Finally, the series of nanoporous glasses with tunable pore structure characteristics were studied. Strong correlations between their structure and the preparation conditions as well as between the resulting transport properties have been shown.
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Castillo, Adriana. "Structure et mobilité ionique dans les matériaux d’électrolytes solides pour batteries tout-solide : cas du grenat Li7-3xAlxLa3Zr2O12 et des Nasicon Li1.15-2xMgxZr1.85Y0.15(PO4)3." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLX107/document.
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L’un des enjeux pour le développement des batteries tout-solide est d’augmenter la conductivité ionique des électrolytes solides. Le sujet de la thèse porte sur l’étude de deux types de matériaux d’électrolytes solides inorganiques cristallins: les Grenat Li7- 3xAlxLa3Zr2O12 (LLAZO) et les Nasicon Li1.15- 2xMgxZr1.85Y0.15(PO4)3 (LMZYPO). L’objectif de cette étude est de comprendre dans quelle mesure les propriétés conductrices des matériaux étudiés sont impactées par des modifications structurales générées soit par un procédé de traitement particulier, soit par une modification de la composition chimique, et ce grâce au croisement des données structurales acquises par diffraction des rayons X (DRX) et Résonance Magnétique Nucléaire (RMN) MAS avec des données de dynamique des ions déduites de mesures de RMN en température et de spectroscopie d’impédance électrochimique (SIE).Les poudres ont été synthétisées après optimisation des traitements thermiques par méthode solide-solide ou solgel. La densification des pastilles utilisées pour les mesures de conductivité ionique par SIE a été réalisée par la technique de frittage Spark Plasma Sintering (SPS).Dans le cas des grenats LLAZO, l’originalité de notre travail est d’avoir montré qu’un traitement de frittage par SPS, au-delà de la densification attendue des pastilles, engendre également des modifications structurales qui ont des conséquences directes sur la mobilité des ions lithium dans le matériau et par conséquent sur la conductivité ionique. Une augmentation franche de la dynamique microscopique des ions lithium après frittage par SPS a en effet été observée par des mesures en température de RMN de 7Li et le suivi des constantes de relaxation.La deuxième partie de l’étude constitue un travail exploratoire sur la substitution de Li+ par Mg2+ dans LMZYPO. Nous avons ainsi étudié les propriétés de conduction ionique de ces composés mixtes Li/Mg, en parallèle d’un examen minutieux des phases cristallines formées. Nous avons notamment montré que la présence de Mg2+ favorise la formation des phases β’ (P21/n) et β (Pbna) moins conductrices ce qui explique la diminution de la conductivité ionique avec le taux de substitution de Li+ par Mg2+ observée dans ces matériaux de type Nasicon.Nos travaux soulignent donc l’importance primordiale des effets de structure sur les propriétés de matériaux d’électrolytes solides de type céramiqueOne of the issues for the development of all-solid-state batteries is to increase the ionic conductivity of solid electrolytes. The thesis work focuses on two types of materials as crystalline inorganic solid electrolytes: a Garnet Li7-3xAlxLa3Zr2O12 (LLAZO) and a Nasicon Li1.15-2xMgxZr1.85Y0.15(PO4)3 (LMZYPO). The objective of this study is to understand to what extent the conduction properties of the studied materials are impacted by structural modifications generated either by a particular treatment process, or by a modification of the chemical composition. Structural data acquired by X-ray diffraction (XRD) and Magic Angle Spinning (MAS) Nuclear Magnetic Resonance (NMR) were then crossed with ions dynamics data deduced from NMR measurements at variable temperature and electrochemical impedance spectroscopy (EIS).The powders were synthesized after optimizing thermal treatments using solid-solid or sol-gel methods. Spark Plasma Sintering (SPS) technique was used for the densification of the pellets used for ionic conductivity measurements by EIS.In the case of garnets LLAZO, the originality of our work is to have shown that a SPS sintering treatment, beyond the expected pellets densification, also generates structural modifications having direct consequences on the lithium ions mobility in the material and therefore on the ionic conductivity. A clear increase of the lithium ions microscopic dynamics after SPS sintering was indeed observed by variable temperature 7Li NMR measurements and the monitoring of the relaxation times.The second part of the study provides an exploratory work on the substitution of Li+ by Mg2+ in LMZYPO. We studied the ionic conduction properties of these mixed Li/Mg compounds, in parallel with a fine examination of the crystalline phases formed. We have showed in particular that the presence of Mg2+ favors the formation of the less conductive β’ (P21/n) and β (Pbna) phases, which explains the decrease of the ionic conductivity with the substitution level of Li+ by Mg2+ observed in these Nasicon type materials.Our work therefore highlights the crucial importance of structural effects on the conduction properties of ceramic solid electrolyte materials
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Mu, Xiaoke [Verfasser], Hans-Joachim [Akademischer Betreuer] Kleebe, and Peter A. van [Akademischer Betreuer] Aken. "TEM study of the structural evolution of ionic solids from amorphous to polycrystalline phases in the case of alkaline earth difluoride systems: Experimental exploration of energy landscape / Xiaoke Mu. Betreuer: Hans-Joachim Kleebe ; Peter A. van Aken." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2013. http://d-nb.info/1107771218/34.
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Saha, Sujoy. "Exploration of ionic conductors and Li-rich sulfides for all-solid-state batteries." Electronic Thesis or Diss., Sorbonne université, 2020. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2020SORUS041.pdf.
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Les besoins croissants en stockage de l’énergie exigent une amélioration continue des batteries lithium-ion. Le mécanisme de redox anionique qui permet d’augmenter la densité d’énergie des électrodes positives mais est associé à divers inconvénients (hystérésis et décroissance de tension, cinétique lente, etc.) qui restent à résoudre. De plus, la sécurité des batteries lithium-ion peut être améliorée en concevant des batteries tout-solide. Dans cette thèse, nous nous sommes d'abord concentrés sur le développement de nouveaux électrolytes solides à base d'oxydes pour des applications dans les batteries tout-solide. Nous avons exploré l’influence du désordre structural sur conductivité ionique des électrolytes solides et montré comment il était possible d’augmenter la conductivité en stabilisant à température ambiante les phases désordonnées présentes à haute température. Ensuite, nous avons conçu des électrodes à base de sulfures riches en Li présentant du rédox anionique, qui en outre présentent une excellente réversibilité. Ainsi, les matériaux d'électrode nouvellement conçus ouvrent une direction possible pour atténuer les problèmes liés au rédox anionique. Enfin, nous avons utilisé les sulfures comme électrode positive dans des batteries tout-solide avec des électrolytes solides à base de sulfures; ces systèmes montrent une excellente cyclabilité, soulignant ainsi l’importance de la compatibilité interfaciale dans les batteries tout-solideGrowing needs for energy storage applications require continuous improvement of the lithium ion batteries (LIB). The anionic redox chemistry has emerged recently as a new paradigm to design high-energy positive electrodes of LIBs, however with some issues (i.e., voltage hysteresis and fading, sluggish kinetics, etc.) that remained to be solved. In addition, the safety of the LIBs can be improved by designing all-solid-state batteries (ASSB). In this thesis, we first focused on the development of new oxide-based solid electrolytes (SE) for applications in ASSBs. We explored the influence of disorder on the ionic conductivity of SEs and demonstrated how to increase the conductivity by stabilizing disordered high-temperature phases. Furthermore, we designed Li-rich layered sulfide electrodes that undergo anionic sulfur redox, with excellent reversibility. Thus, the newly designed electrode materials show a possible direction to mitigate the issues related to anionic redox. Lastly, we used the Li-rich sulfides as positive electrode in ASSB with sulfide-based SEs that demonstrate excellent cyclability, thereby highlighting the importance of interfacial compatibility in ASSBs
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Yousif, F. N. "Core excitons in ionic systems." Thesis, University of York, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377291.
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Young, Kevin Edward. "Ionic conductivity in silicate - containing solid electrolytes." Thesis, University of Exeter, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335654.
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Rageb, Shakir Mahmud. "Ionic transport in lithium salts and composites." Thesis, University of Kent, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278268.
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Avala, Usha Kranthi. "Ionic Conductivity in Non-Ionic Compounds." TopSCHOLAR®, 2013. http://digitalcommons.wku.edu/theses/1279.
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The main objective of this work is to investigate the ionic conductivity of the drugs under certain conditions and also to compare the ionic conductivities of drugs determined by single surface sensors and parallel plate sensors. The ionic conductivity of various materials at their pre-melt and melt states are studied in order to further study a recently discovered phenomenon. Polar solids like Lidocaine, Ketoconazole, Procainamide and Nifedipine were examined in this study. Experimental studies show an increase in ionic conductivity in both pre-melt (20 -30 °C below melting temperature) and melt transition regions. Results of ionic conductivity of both parallel plate and single surface sensor at different frequencies are compared. At 1000 Hz, all the samples show an increase in ionic conductivity with both parallel plate and single surface sensor, but at 0.1 Hz frequency, no increase in ionic conductivity is observed with parallel plate sensor except for Nifedipine.
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Harris, Mark Jonathan. "Phase transitions in related ionic nitrates and carbonates." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386688.
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Chen, Jing. "Solution and solid state interactions between ionic [pi]-systems." Lexington, Ky. : [University of Kentucky Libraries], 2006. http://lib.uky.edu/ETD/ukychem2006d00388/DISSERTATION%5FJING%5FCHEN.pdf.
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Thesis (Ph. D.)--University of Kentucky, 2006.Title from document title page (viewed on March 28, 2006). Document formatted into pages; contains xiv, 167 p. : ill. (some col.). Includes abstract and vita. Includes bibliographical references (p. 128).
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Chen, Jing. "SOLUTION AND SOLID STATE INTERACTIONS BETWEEN IONIC π-SYSTEMS." UKnowledge, 2006. http://uknowledge.uky.edu/gradschool_diss/289.
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Although attractive interactions between π systems (π-π interaction) have been known for many years, understanding of its origin is still incomplete. Quantitative measuring of π-stacking is challenging due to the weak nature of the π-π interaction. This dissertation aims at elucidating a quantitative conformational analysis by NMR ring current anisotropy of an organic compound capable of intramolecular π-stacking in solution and studying charge effects on the stacking of π-systems. This dissertation offers four contributions to the area. (1) A general approach to four-state, conformational analysis based on the magnetic anisotropy of molecules undergoing fast dynamic exchange is described. (2) Study unveiled the importance of charges in the conformation of a dication in the solution. (3) Novel aromatic salt pairs of triangulene derivatives with the delocalized cation-anion interaction were synthesized and studied. (4) Study unveiled ionic π-systems preferred face-to-face stacking due to strong cation-π and anion-cation attractions.
A general protocol for the application of magnetic anisotropy to quantitative multi-state conformational analysis of molecules undergoing fast conformational exchange was suggested in the current study. The reliability of this method of conformational analysis was checked by the mass balance. VT-NMR was also conducted to study the enthalpic parameters. This technique can be further used to study canonical interactions such as ion pairing, hydrogen boning, and molecular recognition.
In the current study, dependence of the probe conformations on the dispersive interactions at the aromatic edges between solvent and probes was tested by conformational distributions of the fluorinated derivatives (2b and 2c) of the probe molecule (1a). Solution and solid studies of these molecules put the previous conclusion drawn by the Cammers group in question. Current studies show that the dispersive interaction at the aromatic edge could not be the predominant force on the conformational changes in the probe molecule 1a during the fluoroalkanol perturbation. This study indicated that charges might be important in the formation of the folding conformations in the solution and solid state of 1a, 2b, and 2c. A contribution of this thesis was to prepare and study a conformational model that lacked charges. The previous molecules were charged.
The solid-state structures of pyridinium-derived aromatic rings from the CSD (Cambridge Structural Database) were studied to investigate the π-π interaction between cationic π-systems in solid state. Novel aromatic salt pairs of triangulene derivatives with the delocalized cation-anion interaction were synthesized to study the π-π interaction between two aromatic rings that carried opposite charges. This study showed that the interaction between ionic π-systems can be enhanced by cation-π and anion-cation attractions. The stackings of these π-systems introduce more overlap, closer packing and stronger atomic contact than that of the solid states of comparable neutral species. Cation-π and anion-cation attractions are synergistic in aromatic salts.
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Oleksy, Anna. "Wetting transitions of ionic solutions at charged solid substrates." Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611681.
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Hjalmarsson, Nicklas. "Ionic liquids : The solid-liquid interface and surface forces." Doctoral thesis, KTH, Yt- och korrosionsvetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-186267.
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Ionic liquids (ILs) present new approaches for controlling interactions at the solid-liquid interface. ILs are defined as liquids consisting of bulky and asymmetric ions, with a melting point below 373 K. Owing to their amphiphilic character they are powerful solvents but also possess other interesting properties. For example, ILs can self-assemble and are attracted to surfaces due to their charged nature. As a result, they are capable of forming nanostructures both in bulk and at interfaces. This thesis describes how the solid-IL interface responds to external influences such as elevated temperatures, the addition of salt and polarisation. An improved understanding of how these factors govern the surface composition can provide tools for tuning systems to specific applications such as friction. Normal and friction forces are measured for ethylammonium nitrate (EAN) immersed between a mica surface and a silica probe, at different temperatures or salt concentrations. The results demonstrate that an increase in temperature or low concentrations of added salt only induce small changes in the interfacial structure and that the boundary layer properties remain intact. In contrast, at sufficiently large salt concentrations the smaller lithium ion prevails and the surface composition changes. The interfacial layer of a similar IL is also investigated upon the addition of salt and the results reveal that lithium ions affect the surface composition differently depending on the ion structure of the IL. This demonstrates that the surface selectivity strongly depends on the ion chemistry. Remarkably, a repulsive double layer force manifests itself for EAN at 393 K, which is not observed for lower temperatures. This indicates a temperature dependent change in EAN’s microscopic association behaviour and has general implications for how ILs are perceived. A new method is developed based on a quartz crystal microbalance to investigate how the surface compositions of ILs respond to polarisation. The approach demonstrates that interfacial layers of both a neat IL and an IL dissolved in oil can be controlled using potentials of different magnitudes and signs. Furthermore, the method enables two independent approaches for monitoring the charges during polarisation which can be used to quantify the surface composition. The technique also provides information on ion kinetics and surface selectivity. This work contributes to the fundamental understanding of the solid-IL interface and demonstrates that the surface composition of ILs can be controlled and monitored using different approaches.Jonvätskor möjliggör nya tillvägagångssätt för att kontrollera interaktioner vid gränsskiktet mellan fasta ytor och vätskor. Jonvätskor definieras som vätskor som består av stora och asymmetriska joner med en smältpunkt under 373 K. På grund av sin amfifila karaktär är de starka lösningsmedel men har också andra intressanta egenskaper. Jonvätskor kan till exempel självorganisera sig och attraheras till ytor på grund av sin laddning. En följd av detta är att de bildar nanostrukturer både i bulk och på ytor. Denna avhandling beskriver hur gränsskiktet mellan fasta ytor och jonvätskor svarar på yttre påverkan såsom en ökning i temperatur, tillsättning av ett salt samt polarisering. En ökad förståelse för hur dessa faktorer styr ytkompositionen av jonvätskor kan bidra med verktyg för att kontrollera system till specifika applikationer såsom friktion. Normala- och friktionskrafter mäts för etylammonium nitrat (EAN) mellan en glimmeryta och en kolloidprob vid olika temperaturer eller saltkoncentrationer. Resultaten visar att en ökning av temperatur eller låga koncentrationer av tillsatt salt bara marginellt framkallar ändringar i strukturen på gränsytan och att det adsorberade lagret förblir intakt. När saltkoncentrationen emellertid var tillräckligt hög får den mindre litiumjonen överhanden och ytsammansättningen ändras. Ytlagret av en liknande jonvätska undersöks också vid tillsättning av salt och resultaten avslöjar att litiumjoner påverkar ytsammansättningen annorlunda beroende på jonstrukturen av jonvätskan. Detta visar att ytselektiviteten starkt beror på jonkemin. En repulsiv dubbellagerkraft yttrar sig anmärkningsvärt för EAN vid 393 K vilket inte observeras vid lägre temperaturer. Detta indikerar en ändring i EANs mikroskopiska sammansättningsbeteende och har generella återverkningar för hur jonvätskor uppfattas. En ny metod har utvecklats baserad på en kvartskristall mikrovåg för att undersöka hur ytsammansättningen av jonvätskor reagerar på polarisering. Denna metod visar att det adsorberade lagret av både en ren jonvätska och en jonvätska löst i olja kan kontrolleras genom att applicera spänningar med olika tecken och storlekar. Dessutom möjliggör metoden två oberoende tillvägagångssätt för att övervaka laddningarna under polarisering vilket kan användas för att kvantifiera ytsammansättningen. Tekniken ger också information om jonkinetik och ytselektivitet. Detta arbete bidrar till den grundläggande förståelsen av gränsskiktet mellan fasta ytor och jonvätskor och visar att ytsammansättningen av jonvätskor kan kontrolleras och övervakas med olika tillvägagångssätt.
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Martins, Dália Teresa Al-Alavi. "Compact ion-source based on superionic rubidium silver iodide (RbAg4I5) solid electrolyte." Master's thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/11037.
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Dissertação para obtenção do Grau de Mestre em
Engenharia FísicaA compact ion-beam source based on rubidium silver iodide (RbAg4I5) solid electrolyte, deposited on a sharpened silver tip, has been developed and studied. Through an accelerating potential above 10 kV, established between emitter and collector, silver positive ions move through the electrolyte towards the emitting surface, where they are emitted from and accelerated. Via partial redox reaction occurring at the silver/RbAg4I5 interface, silver atoms are oxidised into Ag+ ions and migrate into the electrolyte, compensating the loss of emitted ions in the apex region. The emitted ions are collected by a Faraday cup, producing an electric current in the level of tens picoamperes. It was found that silver ions (atomic or clustered) make a major contribution to the measured ion current, although rubidium ions were also detected with concentration in six times lower than silver. The apex diameters of the final emitters were estimated in the range of 4-9 μm. The highest stable current was produced by an emitter whose apex diameter corresponds to 8.2 ± 0.5 μm. This current remained in the level of 20-25 pA for nearly 90 minutes and it was obtained at 92ºC, using an extraction voltage of 20 kV. Furthermore, it was observed that the current increased exponentially with temperature and linearly with applied voltage, at least for temperatures below 150 ºC and voltages in the range of 10-22 kV. Dependence on the apex diameter was not studied, since the RbAg4I5 film deposited on silver tips was not totally uniform. Several improvements should be performed to optimize the deposition methods, the design of heating system and methodology of the measurements (m/z characterization of the emitted particles). However, the developed ion-beam source can produce a stable current over a long period of time with minimal expenditure of energy and source material. Such sources have potential applications in materials science and spacecraft engineering as principal elements of miniaturized electric propulsion systems (ionic thrusters).
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Koronaios, Peter. "Studies of transport and thermodynamic properties of ionic liquids." Thesis, University of Southampton, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243047.
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Chable, Johann. "Électrolytes solides fluorés pour batteries tout solide à ions F-." Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0276/document.
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Ce travail porte sur la synthèse, la mise en forme et la caractérisation desolutions solides de type tysonite RE1-xMxF3-x (RE = La, Sm, Ce et M = Ba, Ca, Sr). Dans unpremier temps, une démarche d’étude rigoureuse est mise en place pour la solution solide ditede référence, La1-xBaxF3-x. Les synthèses menées à l’état solide aboutissent à une maîtrise dela composition chimique et à l'établissement de lois de variations des paramètres structuraux.Une meilleure compréhension de l’influence de la structure sur la mobilité des ions F- estégalement acquise. L’influence du frittage dans l’obtention de bonnes valeurs de conductivitéionique est également à souligner. Dans un second temps, les effets de la nanostructurationpar mécanobroyage sur les propriétés de conductivité sont évalués. L’utilisation de laméthodologie des plans d’expériences mène à la mise au point des réglages optimums debroyage. Il apparaît alors que la synthèse des électrolytes peut être accélérée et mise àl’échelle tout en gardant des valeurs optimales de conductivité. Enfin, la démarche déterminéeest appliquée à d'autres solutions solides de type tysonite et à la recherche du conducteurionique le plus performant. Si les composés issus de la substitution Ce/Sr ou encore Sm/Casemblent les plus prometteurs, la plus grande stabilité chimique de la solution solide La1-xSrxF3-x est le compromis idéal pour l'utiliser comme électrolyte solide lors des mesuresélectrochimiques des batteriesThis work deals with the synthesis, shaping and characterization of RE1-xMxF3-x (RE = La, Sm, Ce et M = Ba, Ca, Sr) tysonite-type solid solutions. In a first part, onemeticulous approach has been set up for La1-xBaxF3-x solid solution, chosen as a reference.The solid-state synthesis of these materials led to a better knowledge of their chemicalcomposition (Vegard’s laws) and of the structure-ionic mobility correlations. The impact ofthe sintering process on the ionic conductivity is also highlighted. In a second part, the effectsof the nanostructuration conducted by ball-milling of the microcrystalline samples areevaluated. The use of the Design of Experiments methodology led to identify the optimummilling conditions. It appears that the synthesis of electrolytes can be sped- and scaled-up,while keeping high ionic conductivity properties. At last, this approach is applied on othertysonite-type solid solutions, to look for the best electrolyte. The Ce/Sr and Sm/Casubstitutions generate very promising ionic conductors but not really (electro)chemicallystable compounds. A compromise has been found with the choice of the La1-xSrxF3-x solidsolution as the FIB electrolyte for the electrochemical performances tests, regarding its higherchemical stability
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Anaredy, Radhika Sudhakar. "The study of ionic liquid behavior at solid-liquid interfaces." Diss., University of Iowa, 2018. https://ir.uiowa.edu/etd/6540.
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Ionic liquids are organic salts with room temperature melting points. Their unique physicochemical properties make them popular choices in the fields of tribology, energy storage and production, and extractions. Previous studies show that IL’s interfacial volume, extending some nanometers from an adjacent surface, is characterized by the self-assembly of IL molecules into ordered structures. This ordering imparts unique properties which often govern the properties of ILs and affect their application in the aforementioned areas. This thesis describes research conducted to understand the behaviors and interactions of ILs at interfaces, along with investigations of bulk IL structures and transitions in the presence of water. The findings reported will help the scientific community by giving insight into the physical and chemical processes surrounding IL behavior, allowing ILs’ physicochemical properties to be more accurately tailored, via judicious synthesis, to a desired application.
Major findings of this work show that the ordered interfacial region may extend up to two orders of magnitude further from the interface than previously thought. Specifically, this thesis shows several examples of reversible IL self-assembly into long-range ordered films that extend up to ~ 2 μm from a surface. This is approximately twelve times the thickness of interfacial region previously reported.
Temperature controlled studies on the bulk structure of an IL at its phase transition temperatures aid in understanding the structural arrangement of molecules in the bulk fluid as a function of temperature. Spectroscopic analyses of these bulk studies and the above interfacial systems showed no similarities, indicating that the self-assembled interfacial structures are, in fact, unique.
Being hygroscopic in nature, water is the most common impurity found in ILs. Water can affect IL intermolecular forces and the resulting structures in bulk fluids as well as at the interface. One of the chapter of this thesis describes these interactions, and the variably hydrated IL structures for two classes of ILs via spectroscopic and electrochemical techniques.
The outcomes of this thesis will aid the community in understanding interfacial and bulk structures of ILs, as well as influences of temperature and water on these structures. The description of extended IL structures provides valuable insights into new design principles for truly task-specific ILs.
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Zhang, Long. "CHARGE TRANSPORT IN ELECTRONIC-IONIC COMPOSITES." UKnowledge, 2017. http://uknowledge.uky.edu/cme_etds/79.
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The goal of this thesis is to generate fundamental understandings of charge transport behaviors of composites consisting of garnet structured Al substituted Li7La3Zr2O12 (LLZO) electrolyte and LiCoO2 electrode. In order to take full advantage of all-solid-state batteries, bulk type composite electrodes should be introduced to increase energy and power density. However, the charge utilization of bulk type composite electrodes is quite low. Understanding ionic conduction behavior is, therefore, important for improving the performance of all-solid-state batteries, because ion conduction within solids depends on effective pathways. Electronic conductivity can be easily compensated by adding carbon black, but ionic conductivity can only depend on composites electrode itself. Here, we show that electronic and ionic conductivities of composites consisting of LiCoO2 and Al doped LLZO can be achieved separately. 3D reconstructed image obtained from focused ion beam-scanning electron microscope (FIB-SEM) demonstrates that porosity, percolation, and grain boundaries often play antagonistic roles in controlling the charge transport behaviors in the composite electrodes, resulting in an overall conductivity dominated by electrons. This work suggests an approach to optimize electronic and ionic conductivities for bulk type composite electrodes, which may eventually be utilized in all-solid-state batteries.
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Hammam, E. S. "Studies of the electrical properties of solid ionic halides and oxides." Thesis, University of Kent, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374832.
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Wang, Xiaodi. "Ionic Conducting Composite as Electrolyte forLow Temperature Solid Oxide Fuel Cells." Licentiate thesis, KTH, Functional Materials, FNM, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-24723.
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Solid oxide fuel cells (SOFCs) are considered as one of the most promising powergeneration technologies due to their high energy conversion efficiency, fuel flexibilityand reduced pollution. The current SOFCs with yttria-stabilized zirconia (YSZ)electrolyte require high operation temperature (800-1000 °C), which not only hinderstheir broad commercialization due to associated high cost and technologicalcomplications. Therefore, there is a broad interest in reducing the operating temperatureof SOFCs. The key to development of low-temperature SOFCs (LTSOFCs) is to explorenew electrolyte materials with high ionic conductivity at such low temperature (300-600 °C).Recently, ceria-based composite electrolyte, consisting of doped cerium oxide mixedwith a second phase (e.g. Na2CO3), has been investigated as a promising electrolyte forLTSOFCs. The ceria-based composite electrolyte has shown a high ionic conductivityand improved fuel cell performance below 600 °C. However, at present the developmentof composite electrolyte materials and their application in LTSOFCs are still at an initialstage. This thesis aims at exploring new composite systems for LTSOFCs with superiorproperties, and investigates conductivity behavior of the electrolyte. Two compositesystems for SOFCs have been studied in the thesis.In the first system, a novel concept of non-ceria-salt-composites electrolyte, LiAlO2-carbonate (Li2CO3-Na2CO3) composite electrolyte, was investigated for SOFCs. TheLiAlO2-carbonate electrolyte exhibited good conductivity and excellent fuel cellperformances below 650 oC. The ion transport mechanism of the LiAlO2-carbonatecomposite electrolyte was studied. The results indicated that the high ionic conductivityrelates to the interface effect between oxide and carbonate.In the second system, we reported a novel core-shell samarium-doped ceria(SDC)/Na2CO3 nanocomposite which is proposed for the first time, since the interface isdominant in the nanostructured composite materials. The core-shell nanocompositeparticles are smaller than 100 nm with amorphous Na2CO3 shell. The nanocompositeelectrolyte was applied in LTSOFCs and showed excellent performance. Theconductivity behavior and charge carriers have been studied. The results indicated that H+conductivity in SDC/Na2CO3 nanocomposite is predominant over O2- conductivity with1-2 orders of magnitude in the temperature range of 200-600 °C. It is suggested that theinterface in composite electrolyte supplies high conductive path for proton, while oxygenions are most probably transported by the SDC nano grain interiors. Finally, a tentativemodel “swing mechanism” was proposed for explanation of superior proton conduction.
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Zhang, Yuelan. "Synthesis and Characterization of Nanostructured Electrodes for Solid State Ionic Devices." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14000.
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The demands for advanced power sources with high energy efficiency, minimum environmental impact, and low cost have been the impetus for the development of a new generation of batteries and fuel cells. One of the key challenges in this effort is to develop and fabricate effective electrodes with desirable composition, microstructure and performance. This work focused on the design, fabrication, and characterization of nanostructured electrodes in an effort to minimize electrode polarization losses.
Solid-state diffusion often limits the utilization and rate capability of electrode materials in a lithium-ion battery, especially at high charge/discharge rates. When the fluxes of Li+ insertion or extraction exceed the diffusion-limited rate of Li+ transport within the bulk phase of an electrode, concentration polarization occurs. Further, large volume changes associated with Li+ insertion or extraction could induce stresses in bulk electrodes, potentially leading to mechanical failure. Interconnected porous materials with high surface-to-volume ratio were designed to suppress the stress and promote mass transport. In this work, electrodes with these unique architectures for lithium ion batteries have been fabricated to improve the cycleability, rate capability and capacity retention.
Cathodic interfacial polarization represents the predominant voltage loss in a low-temperature SOFC. For the first time, regular, homogeneous and bimodal porous MIEC electrodes were successfully fabricated using breath figure templating, which is self-assembly of the water droplets in polymer solution. The homogeneous macropores promoted rapid mass transport by decreasing the tortuosity. And mesoporous microstructure provided more surface areas for gas adsorption and more TPBs for the electrochemical reactions. Moreover, composite electrodes were developed with a modified sol-gel process for honeycomb SOFCs. The sol gel derived cathodes with fine grain size and large specific surface area, showed much lower interfacial polarization resistances than those prepared by other existing processing methods.
Nanopetals of cerium hydroxycarbonate have been synthesized via a controlled hydrothermal process in a mixed water-ethanol medium. The formation of the cerium compound depends strongly on the composition of the precursors, and is attributed to the favored ethanol oxidation by Ce(IV) ions over Ce(IV) hydrolysis process. Raman studies showed that microflower CeO2 preferentially stabilizes O2 as a peroxide species on its surface for CO oxidation.
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ruan, cunfan. "Constructing an Ionic diode using Solid Supported Lipid bilayers: A Proposal." Scholarship @ Claremont, 2018. http://scholarship.claremont.edu/cmc_theses/1829.
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Ionic-type transistors are important devices for precise chemical control and biosensing applications. Previous work by Tybrandt et al. has demonstrated a novel approach to constructing an ionic transistor using conducting polymers poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and quarternized- polyvinyl benzyl chloride (q-PVBC). This approach could be combined with the 3D stamp method of generating concentration gradients in supported lipid bilayers (SLBs) as shown by Liu et al. to create a charged lipid-based ionic polar junction transistor. An electric potential applied across the SLB would drive charged lipids towards the opposite electrode, thus generating current flow across the SLB. Incorporation of a charged-lipid functionalized PEDOT derivative as demonstrated by Johansson et al. would allow a longer period of current flow before charge carriers are depleted. Such a device could offer novel approaches to biosensing.
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Zhao, Qichao. "Ionic Liquid Materials as Gas Chromatography Stationary Phases and Sorbent Coatings in Solid-Phase Microextraction." University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1320963975.
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Xie, ZongHai. "Nuclear spin relaxation studies of ionic and defect mobility in lithium oxide." Thesis, University of Kent, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387044.
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Otaduy, Maria Concepcion Garcia. "A nuclear magnetic resonance study of ionic dynamics in solid polymer electrolytes." Thesis, University of Kent, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263697.
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Joshi, Manishkumar Dilipkumar. "Synthesis of New Classes of Ionic Liquids and Polymeric Ionic Liquids and their Applications in Microextraction Techniques." University of Toledo / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1372871956.
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Given, M. J. "The influence of ions on water tree growth in polyethylene." Thesis, University of Strathclyde, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381492.
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De, Vita Alessandro. "The energetics of defects and impurities in metals and ionic materials from first principles." Thesis, Keele University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332301.
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The study of defects in metals and ionic solids has been the subject of great theoretical and experimental interest, in basic as well as applied research areas. The present work collects two series of calculations on the energetics of a variety of defective systems, in a metal host matrix (Al), and in two ionic oxides (MgO and Li20) . The energetics and the electronic ground state of the vacancy, of the self-interstitial, and of the hydrogen impurity systems in Al were investigated. The formation and migration energies of Schottky defects in MgO and Frenkel Defects in Li20 were also studied. All results are in close agreement with experiment, while the work gives new insight into the localisation of defects, the role played by lattice relaxation effects, and the defectinduced redistribution of valence electrons. The calculations are based on density functional and pseudopotential theory, make use the supercell approach, and employ in different implementations the conjugate gradients technique to minimise the total energy functional. For the calculations on oxides, we made use of a newly developed parallel computing methodology
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Sivapalan, Nagalingam. "Electrical and electrochemical studies of some solid electrolytes." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.236018.
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In Chapter 1 solid electrolytes are reviewed. The historical development, mechanism of ionic conduction in solids and the properties and applications of important solid electrolytes are given. Chapter 2 discusses impedance methods as applied to electrochemistry and the equivalent circuit representation of the solid electrolyte/electrode interface. The application of a computer program that gives theoretical impedance and/or admittance plots is also described. The application of four-electrode conductivity measurements to solid electrolytes is described in Chapter 3. Since this is the first time these four-electrode measurements have been employed with solid electrolytes, a detailed review of the theoretical calculations and the errors involved are presented. The results from the experiments on the solid electrolyte PyAg5I6(Py=C5H6N) are also given. In Chapter 4, the cathodic deposition of silver from PyAg5I6 and its subsequent recovery by anodic polarisation are examined. The behaviour of solid silver and silver painted electrodes in this perspective is compared. The solid electrolyte galvanic cell AgmidPyAg5I6midMe4NI5, C is investigated in Chapter 5. Various cell parameters are measured and the charge/discharge characteristics examined. Finally in Chapter 6 the behaviour of zeolites as solid ionic conductors is reviewed and the results of some preliminary studies on zeolite-Y are presented.
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Bokun, G. S., Ya G. Groda, R. N. Lasovsky, and V. S. Vikhrenko. "Charge Distribution Around Nanoscale Nonhomogeneities in Solid State Ionics." Thesis, Sumy State University, 2015. http://essuir.sumdu.edu.ua/handle/123456789/42717.
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The system of Nernst-Planck-Poisson equations is modified by including the gradient terms in the chemical potential expression. The gradient terms are important in the regions of significant inhomogeneities, e. g. near the interface boundaries. These modified equations are used for investigating the particle density distribution in the vicinity of interphase boundary of a solid electrolyte. The differential equation
of the fourth order for the problem of contact between two solid phases is formulated. Its analytic solution which describes non monotonic distribution of charge in both phases is obtained. It is shown that the gradient component added in the transport equations makes a decisive contribution in the double layer region. The approach is further expanded to the system composed of bulk phases and the intergrain layer between
them. The particle density distributions at different conditions are investigated. The quasy-one dimensional lattice model of the fuel cell is considered in the frame of kinetic Monte Carlo simulation. It is shown that the electrostatic interaction between ions makes a significant contribution to the activation energy of migration of the particles. On the other hand, the fluctuations of the energy barriers slightly increase the particle
migration activation energy. It is found that at blocked electrodes in the near electrode regions electrical double layers are formed. The thickness of the electrical double layer is around few lattice constants.
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Santos, Ana Rute Duarte dos. "Study on solubility of pharmaceutical compounds in ionic liquids." Master's thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/9660.
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Dissertation to obtain the degree of master in Chemical and Biochemical EngineeringThe sufficient solubility of N-acetyl-L-cysteine (NAC), coumarin (COU) and 4-hydroxycoumarin (4HC) in alternative solvents obtained in this work can open new perspectives in pharmaceutical processing. Solid–liquid equilibrium (SLE) measurements have been made using a dynamic (synthetic) method. The melting point and the enthalpy of fusion of the pharmaceutical compounds were acquired using differential scanning calorimetry (DSC). The solubility of N-acetyl-L-cysteine and 4-hydroxycoumarin in trifluoromethanesulfonate ionic liquids was found to be significantly higher than in the studied bis(trifluoromethylsulfonyl)imide ionic liquids, and when compared, coumarin have the opposite behaviour. The best solvent amongst studied for this antioxidant (NAC) and anticoagulants (COU and 4HC) was discovered. The solid–liquid phase equilibrium were described using six different correlation equations which revealed relatively good description with the acceptable standard deviation temperature range. Moreover, the solubility data was used to calculate the 1-octanol/water partition coefficients and experimental partition coefficients (logP) was found to be negative in N-acetyl-L-cysteine and positive in the case of coumarin, at five temperatures with N-acetyl-L-cysteine being more hydrophilic and coumarin more hydrophobic; These results are also proof of the possibility of using these compounds as pharmaceutical products.
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Najafi, Ali. "Application of Polymeric Ionic Liquid Solid-Phase Microextraction Sorbent Coatings and Ionic Liquid Stationary Phases for Liquid and Multidimensional Gas Chromatographic Techniques." University of Toledo / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1449846148.
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Chiabrera, Francesco Maria. "Interface Engineering in Mixed Ionic Electronic Conductor Thin Films for Solid State Devices." Doctoral thesis, Universitat de Barcelona, 2019. http://hdl.handle.net/10803/667601.
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Interface-dominated materials such as nanocrystalline thin films have emerged as an enthralling class of materials able to engineer functional properties of transition metal oxides widely used in energy and information technologies. In this direction, it has been recently proved that grain boundaries (GBs) in the perovskite La1-xSrxMnO3±δ (manganite) deeply impact its functional properties, boosting the oxygen mass transport while abating the electronic and magnetic order. The impact of grain boundary in nanocrystalline thin films is so relevant to radically change the behaviour of the material, transforming an electronic conductor into a mixed ionic-electronic conductor functional for redox-based solid state devices. Based on these preliminary studies, it became crucial to understand the origin of this enhancement, in order to gain engineering capabilities and potentially extend it to other functional perovskite materials.
Following this approach, this thesis focuses in analysing the remarkable properties of GBs in manganites and, ultimately, investigating the possibility of engineering these interfaces. First, the structural and chemical characterization of the LSM thin films deposited by pulsed laser deposition (PLD) is presented. The compositional analysis of the layers revealed a severe Mn deficiency, ascribed to the plasma-background interactions during the deposition. The analysis of the GBs of these Mn-deficient thin films revealed a remarkable local modification of ionic composition, consisting in a Mn and O depletion along with a La and Sr enrichment (viz. GBdef). Then, through a PLD combinatorial approach, Mn was progressively inserted in the perovskite structure, altering the overall cationic ratio of the thin films (Mn/(La+Sr)). The variation of cationic chemical potential of the thin films was observed to significantly affect the GB composition, which passed from Mn depletion (La-enrichment) to Mn enrichment (La-depletion), while maintaining an O deficiency character (viz. GBrich). This behaviour suggests that through the tuning of the overall cationic concentration in the thin films the GB composition can be altered, offering an innovative way for engineering chemical defects in strained interfaces.
The effect of these different GBs on the electrical conductivity and the oxygen mass transport properties of LSM thin films with different Mn content was then measured. It was found that in the layers characterized by GBdef, the lack of Mn hinders the low temperature metal insulator transition and, in its place, a variable range hopping mechanism occurs, where electrons tunnels across the GBs for reaching distant Mn atoms. Moreover, a simultaneous decrease of activation energies of both GB oxygen diffusivity and GB oxygen surface exchange coefficient was observed further decreasing the Mn concentration in these thin films, indicating a strong interdependence between the two phenomena. The results suggest that the GB accumulation of oxygen vacancies is at the origin of the large improvement of both oxygen mass transport parameters observed in LSM polycrystalline thin films.
In LSM thin films characterized by GBrich, the low temperature metallic behaviour is progressively restored and an increase of electronic conductivity is observed in the entire temperature range. Additionally, in these layers relative changes of Mn do not give rise to a variation of the oxygen diffusivity, meaning that the GBs oxygen vacancy concentration is not altered anymore. Overall, the results demonstrate the possibility of engineering the functional properties of LSM polycrystalline thin films by modifying the GB cationic composition.
In the third part of the thesis, the effect of Co substitution on LSMC functional properties was investigated. The LSMC thin films were produced by combinatorial PLD, which allow a direct measure of real-continuous spread LSMC system. The oxygen mass transport properties of bulk and GB were evaluated by finite element model fitting of 18O exchange profiles. The results revealed that GBs enhance the transport properties of the whole material in the range of composition under study, although for high Co concentration the GB effect is concealed by the high bulk diffusion.
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Petit, Dominique, Jean-Pierre Korb, Pierre Levitz, Jean LeBideau, and D. Brevet. "Molecular dynamics of ionic liquids confined in solid silica matrix for lithium batteries." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-191885.
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We present the first results of the magnetic field dependence of the longitudinal nuclear magnetic relaxation of anion-cation
pair of ionic liquids (Li+-ionogels) confined within a silica-like mesoporous matrices designed for lithium batteries. These results are in favour of a very-correlated dynamical motion of the anion-cation pair within the solid and disordered silica matrix.
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Petit, Dominique, Jean-Pierre Korb, Pierre Levitz, Jean LeBideau, and D. Brevet. "Molecular dynamics of ionic liquids confined in solid silica matrix for lithium batteries." Diffusion fundamentals 10 (2009) 7, S. 1-3, 2009. https://ul.qucosa.de/id/qucosa%3A13045.
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We present the first results of the magnetic field dependence of the longitudinal nuclear magnetic relaxation of anion-cation
pair of ionic liquids (Li+-ionogels) confined within a silica-like mesoporous matrices designed for lithium batteries. These results are in favour of a very-correlated dynamical motion of the anion-cation pair within the solid and disordered silica matrix.
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Chinnam, Parameswara Rao. "MULTI-IONIC LITHIUM SALTS FOR USE IN SOLID POLYMER ELECTROLYTES FOR LITHIUM BATTERIES." Diss., Temple University Libraries, 2015. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/311780.
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ChemistryPh.D.
Commercial lithium ion batteries use liquid electrolytes because of their high ionic conductivity (>10-3 S/cm) over a broad range of temperatures, high dielectric constant, and good electrochemical stability with the electrodes (mainly the cathode cathode). The disadvantages of their use in lithium ion batteries are that they react violently with lithium metal, have special packing needs, and have low lithium ion transference numbers (tLi+ = 0.2-0.3). These limitations prevent them from being used in high energy and power applications such as in hybrid electric vehicles (HEVs), plug in electric vehicles (EVs) and energy storage on the grid. Solid polymer electrolytes (SPEs) will be good choice for replacing liquid electrolytes in lithium/lithium ion batteries because of their increased safety and ease of processability. However, SPEs suffer from RT low ionic conductivity and transference numbers. There have been many approaches to increase the ionic conductivity in solid polymer electrolytes. These have focused on decreasing the crystallinity in the most studied polymer electrolyte, polyethylene oxide (PEO), on finding methods to promote directed ion transport, and on the development of single ion conductors, where the anions are immobile and only the Li+ ions migrate (i.e. tLi+ = 1). But these attempts have not yet achieved the goal of replacing liquid electrolytes with solid polymer electrolytes in lithium ion batteries. In order to increase ionic conductivity and lithium ion transference numbers in solid polymer electrolytes, I have focused on the development of multi-ionic lithium salts. These salts have very large anions, and thus are expected to have low tanion- and high tLi+ transference numbers. In order to make the anions dissociative, structures similar to those formed for mono-ionic salts, e.g. LiBF4 and lithium imides have been synthesized. Some of the multi-ionic salts have Janus-like structures and therefore can self-assemble in polar media. Further, it is possible that these salts may not form non-conductive ion pairs and less conductive ion triplets. First, we have prepared nanocomposite electrolytes from mixtures of two polyoctahedral silsesquioxanes (POSS) nanomaterials, each with a SiO1.5 core and eight side groups. POSS-PEG8 has eight polyethylene glycol side chains that have low glass transition (Tg) and melt (Tm) temperatures and POSS-phenyl7(BF3Li)3 is a Janus-like POSS with hydrophobic phenyl groups and -Si-O-BF3Li ionic groups clustered on one side of the SiO1.5 cube. The electron-withdrawing POSS cage and BF3 groups enable easy dissociation of the Li+. In the presence of polar POSS-PEG8, the hydrophobic phenyl rings of POSS-phenyl7(BF3Li)3 aggregate and crystallize, forming a biphasic morphology, in which the phenyl rings form the structural phase and the POSS-PEG8 forms the conductive phase. The -Si-O-BF3- Li+ groups of POSS-phenyl7(BF3Li)3 are oriented towards the polar POSS-PEG8 phase and dissociate so that the Li+ cations are solvated by the POSS-PEG8. The nonvolatile nanocomposite electrolytes are viscous liquids that do not flow under their own weight. POSS-PEG8/POSS-phenyl7(BF3Li)3 at O/Li = 16/1 has a conductivity, σ = 2.5 x 10-4 S/cm at 30°C, 17 x greater than POSS-PEG8/LiBF4, and a low activation energy (Ea ~ 3-4 kJ/mol); σ = 1.6 x 10-3 S/cm at 90°C and 1.5 x 10-5 S/cm at 10°C. The lithium ion transference number was tLi+ = 0.50 ± 0.01, due to reduced mobility of the large, bulky anion and the system exhibited low interfacial resistance that stabilized after 3 days (both at 80°C). Secondly, solid polymer electrolytes have been prepared from the same salt, POSS-phenyl7(BF3Li)3 and polyethylene oxide (PEO). These exhibit high ambient temperature conductivity, 4 x 10-4 S/cm, and transference number, tLi+ = 0.6. A two-phase morphology is proposed in which the hydrophobic phenyl groups cluster and crystallize, and the three -BF3- form an anionic pocket, with the Li+ ions solvated by the PEO phase. The high ionic conductivity results from interfacial migration of Li+ ions loosely bonded to three -BF3- anions and the ether oxygens of PEO. Physical crosslinks formed between PEO/Li+ chains and the POSS clusters account for the solid structure of the amorphous PEO matrix. The solid polymer electrolyte has an electrochemical stability window of 4.6 V and excellent interfacial stability with lithium metal. In order to further enhance the ionic conductivity of solid polymer electrolytes, we have made two improvements. First, we have used so called half cube structures, T4-POSS, that contain 4 phenyl groups on one side of a Si-O- ring, and 4 ionic groups on the other side, and so are true Janus structures. They contain a 4/4 ratio of phenyl/ionic groups, unlike the previous structures that contain 7 phenyl groups/3 ionic groups. At the same O/Li ratio, the ionic conductivity of [PhOSi(OLi)]4 with POSS-PEG8 is higher than POSS-phenyl7Li3 because of more Li+ dissociation in the former case. Second, we have increased the dissociation of the lithium salts by replacing the Si-O-BF3Li groups with Si-(C3H4NLiSO2CF3)4. Both T4-POSS-(C3H4NLiSO2CF3)4 and POSS-(C3H4NLiSO2CF3)8 have been synthesized and characterized, with some preliminary conductivity data obtained.
Temple University--Theses
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Pornprasertsuk, Rojana. "Ionic conductivity studies of solid oxide fuel cell electrolytes and theoretical modeling of an entire solid oxide fuel cell /." May be available electronically:, 2007. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Currie, David Blake. "A study of cation replacement in perovskite-related systems including high temperature superconductors." Thesis, University of the West of Scotland, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254391.
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Keen, David Anthony. "Determination of the structure of disordered materials by neutron scattering." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.253382.
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Tole, Philip. "Ab initio studies of polarisabilities of ions in crystals." Thesis, University of Exeter, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.236521.
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Cox, Paul Andrew. "Theoretical and experimental studies of superionic mixed-metal fluorides." Thesis, Keele University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277151.
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Saha, Sudipto. "Lithium Ionic Conductivity and Stability Of Cubic Li7La3Zr2O12 Solid Electrolyte A First-Principles Study." Thesis, North Dakota State University, 2020. https://hdl.handle.net/10365/32052.
Full textAbstract:
Garnet structured cubic LLZO crystal (Li56La24Zr16O96) is one of the most promising solid electrolytes for next-generation solid-state lithium-ion batteries. Ab initio molecular dynamics simulations have been employed to study the impacts of lithium vacancy defect and doping concentration on the lithium ionic conductivity and stability of LLZO. The number of lithium atoms in a unit cell of LLZO has been reduced from 56 to 53, where 56 lithium atoms represent the structure of stoichiometric LLZO, i.e., Li7La3Zr2O12. Similarly, the effect of Al and Ga doping on the conductivity and stability of LLZO material was also investigated. Our computational results confirm that both the defects help in enhancing the conductivity of LLZO and the concentration of defect introduced controls the trade-off between the conductivity and stability. Overall, this study provides a valuable insight into the enhancement of conductivity of cubic LLZO garnet material along with structural stability.
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WInd, Julia. "A combined experimental and computational approach to understanding and developing new solid-state ionic conductors." Thesis, The University of Sydney, 2017. http://hdl.handle.net/2123/17610.
Full textAbstract:
Materials that exhibit significant mobility of several different types of charge carriers (e.g., oxide ions, protons and electrons) have diverse potential applications as fuel-cell membranes, electrodes, batteries, and sensors. A thorough understanding of the fundamental atomic-scale mechanisms of the conduction processes in these materials and their relationship to chemical composition, crystal structure and lattice dynamics is necessary to suggest ways in which the local chemistry and structure of these materials can be modified to lower activation barriers and optimise pathways for conduction. This project set out to thoroughly characterise the crystal structures and dynamics of ionic conductivity in complex solid-state materials, at a level that would permit the rational design of new and improved versions, using a combined experimental and computational approach. On the experimental side, powder samples and single crystals of promising materials were synthesised. These materials were characterised structurally using a variety of diffraction techniques combined with X-ray absorption spectroscopy measurements, to understand the relationship between the average structure and local coordination environments. The central techniques were then inelastic and quasielastic neutron scattering (INS, QENS). Being sensitive to all dynamic processes – the incoherent diffusive motions and coherent lattice vibrations – INS and QENS are able to provide an overview of the entire dynamic processes in the material over the time scale of several femtoseconds to a few picoseconds. Finally, ab initio density functional theory calculations, in the form of single point energy calculations, geometry optimisations and molecular dynamics simulations were used to supplement our experiments and help correlate physical properties with structure and dynamics.