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Tesis sobre el tema "Diffusion du lithium"

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Publicado: 29 de marzo de 2025

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1

Senyshyn, A., M. Monchak, O. Dolotko y H. Ehrenberg. "Lithium Diffusion and Diffraction". Diffusion fundamentals 21 (2014) 4, S.1, 2014. https://ul.qucosa.de/id/qucosa%3A32392.

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In the current contribution the application of bond valence method for the prediction (and diffraction-based techniques for the evalution) of ion diffusion pathways in different materials for electrochemical energy conversion and storage will be presented and discussed.
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2

Li, Juchuan. "UNDERSTANDING DEGRADATION AND LITHIUM DIFFUSION IN LITHIUM ION BATTERY ELECTRODES". UKnowledge, 2012. http://uknowledge.uky.edu/cme_etds/12.

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Lithium-ion batteries with higher capacity and longer cycle life than that available today are required as secondary energy sources for a wide range of emerging applications. In particular, the cycling performance of several candidate materials for lithium-ion battery electrodes is insufficient because of the fast capacity fading and short cycle life, which is mainly a result of mechanical degradation. This dissertation mainly focuses on the issue of mechanical degradation in advanced lithium-ion battery electrodes. Thin films of tin electrodes were studied where we observed whisker growth as a result of electrochemical cycling. These whiskers bring safety concerns because they may penetrate through the separator, and cause short-circuit of the electrochemical cells. Cracking patterns generated in amorphous silicon thin film electrodes because of electrochemical cycling were observed and analyzed. A two-dimensional spring-block model was proposed to successfully simulate the observed cracking patterns. With semi-quantitative study of the cracking pattern features, two strategies to void cracking in thin-film electrodes were proposed, namely reducing the film thickness and patterning the thin-film electrodes. We also investigated electrodes consisting of low melting point elements and showed that cracks can be self-healed by the solid-to-liquid phase transformation upon cycling. Using gallium as an example, mechanical degradation as a failure mechanism for lithium-ion battery electrodes can be eliminated. In order to quantitatively understand the effect of surface modification on electrodes, we analyzed diffusion equations with boundary conditions of finite interfacial reactions, and proposed a modified potentialstatic intermittent titration technique (PITT) as an electro-analytical technique to study diffusion and interfacial kinetics. The modified PITT has been extended to thin-film geometry and spherical geometry, and thus can be used to study thin-film and composite electrodes consisting of particles as active materials.
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3

Heitjans, Paul. "Diffusion in lithium ion conductors – from fundamentals to applications". Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-181798.

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4

Swanson, Claudia H., Michael Schulz, Holger Fritze, Jianmin Shi, Klaus-Dieter Becker, Peter Fielitz y Günter Borchardt. "Examinations of high-temperature properties of stoichiometric lithium niobate". Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-186802.

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5

Epp, Viktor, Christian Brünig, Martin Wilkening, Michael Binnewies y Paul Heitjans. "Lithium diffusion studies of gas-phase synthesized amorphous oxides". Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-188235.

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6

Heitjans, Paul. "Diffusion in lithium ion conductors – from fundamentals to applications". Diffusion fundamentals 20 (2013) 19, S. 1-2, 2013. https://ul.qucosa.de/id/qucosa%3A13583.

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7

Rahn, J., E. Hüger, E. Witt, P. Heitjans y H. Schmidt. "Lithium Self-Diffusion in Single Crystalline and Amorphous LiAlO2". Diffusion fundamentals 21 (2014) 16, S.1, 2014. https://ul.qucosa.de/id/qucosa%3A32425.

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8

Berggren, Elin. "Diffusion of Lithium in Boron-doped Diamond Thin Films". Thesis, Uppsala universitet, Molekyl- och kondenserade materiens fysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-413090.

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In this thesis, the diffusion of lithium was studied on boron-doped diamond (BDD) as a potential anode material in lithium ion batteries (LIB). The initial interaction between deposited lithium and BDD thin films was studied using X-ray Photoelectron Spectroscopy (XPS). Diffusion is directly linked to reactions between lithium and carbon atoms in the BDD-lithium interface. By measuring binding energies of core-electrons of carbon and lithium before and after deposition, these reactions can be analyzed. Scanning Electron Microscopy (SEM) was used to study the BDD surface and the behaviour of deposited lithium. Experiments show that a chemical interaction occurs between lithium and carbon atoms in the surfacelayers of the BDD. The diffusion of lithium is discussed from spectroscopic data and suggests that surface diffusion is occurring and no proof of bulk diffusion was found. The results do not exclude bulk diffusion in later states but it was not found in the initial interaction at the interface after depositing lithium. SEM images show that lithium clusters in the nanometer range are formed on the BDD surface. The results of this study give insights in the initial diffusion behaviour of lithium at the BDD interface and possible following events are discussed.
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9

Ohlendorf, Gerd, Denny Richter, Jan Sauerwald y Holger Fritze. "High-temperature electrical conductivity and electromechanical properties of stoichiometric lithium niobate". Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-192902.

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High temperature properties such as electrical conductivity (σ) and resonance behaviour of stoichiometric lithium niobate (LiNbO3) are determined in the temperature range from 20 to 950 °C. The activation energy of the conductivity is found to be 0.9 and 1.7 eV in the temperature range from 500 to 750 °C and from 800 to 950 °C, respectively. During thermal treatments in ambient air up to 950 °C and back, the conductivity remains unchanged at a given temperature, i.e., the crystal is stable under these conditions. The oxygen partial pressure (pO2) dependence of the conductivity shows two distinct ranges. At 750 °C, the property remains unchanged down to 10−15 bar. Below 10−15 bar, the conductivity increases according to σ ~ (pO2)−1/5. Z-cut LiNbO3 plates can be excited to thickness mode vibrations up to at least 900 °C. At this temperature, the quality factor Q is found to be between 30 and 100. As for changes of the conductivity, a decrease of the resonance frequency is observed below 10−15 bar indicating a correlation of both properties. In order to evaluate the lithium evaporation, the crystals are tempered at 900 °C in ambient air for 24 h. A depth profile of the constituents does not indicate lithium loss within the accuracy of the secondary ion mass spectroscopy. The preliminary results underline the potential of stoichiometric LiNbO3 for high-temperature applications and justify its closer investigation.
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10

Moore, Charles J. (Charles Jacob). "Ab initio screening of lithium diffusion rates in transition metal oxide cathodes for lithium ion batteries". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/79562.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 57-62).
A screening metric for diffusion limitations in lithium ion battery cathodes is derived using transition state theory and common materials properties. The metric relies on net activation barrier for lithium diffusion. Several cathode materials are screened using this approach: [beta]'-LiFePO4, hexagonal LiMnBO3, monoclinic LiMnBO3, Li 3Mn(CO3)(PO4), and Li9V3 (P2O7)3(PO4) 2. The activation barriers for the materials are determined using a combined approach. First, an empirical potential model is used to identify the lithium diffusion topology. Second, density functional theory is used to determine migration barriers. The accuracy of the empirical potential diffusion topologies, the density functional theory migration barriers, and the overall screening metric are compared against experimental evidence to validate the methodology. The accuracy of the empirical potential model is also evaluated against the density functional theory migration barriers.
by Charles J. Moore.
S.M.
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11

Swanson, Claudia H., Michael Schulz, Holger Fritze, Jianmin Shi, Klaus-Dieter Becker, Peter Fielitz y Günter Borchardt. "Examinations of high-temperature properties of stoichiometric lithium niobate". Diffusion fundamentals 12 (2010) 48, 2010. https://ul.qucosa.de/id/qucosa%3A13886.

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12

Pharr, Matt Mathews. "Diffusion, Deformation, and Damage in Lithium-Ion Batteries and Microelectronics". Thesis, Harvard University, 2014. http://dissertations.umi.com/gsas.harvard:11593.

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This thesis explores mechanical behavior of microelectronic devices and lithium-ion batteries. We first examine electromigration-induced void formation in solder bumps by constructing a theory that couples electromigration and creep. The theory can predict the critical current density below which voids do not form. Due to the effects of creep, this quantity is found to be independent of the solder size and decrease exponentially with increasing temperature, different from existing theories.
Engineering and Applied Sciences
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13

Krsulich, Kevin D. "Pulsed field gradient magnetic resonance measurements of lithium-ion diffusion". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/95617.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 2014.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 102-119).
The transport of lithium ions between the electrolyte-electrode interface and the electrode bulk is an essential and presently rate limiting process in the high-current operation of lithium-ion batteries. Despite their importance, few methods exist to experimentally investigate these macroscopic diffusion processes and, as a result, much remains unknown regarding their underlying mechanisms and the resulting macroscopic transport. Gradient nuclear magnetic resonance measurements are a mature and effective means of investigating macroscopic transport phenomena and posses several advantages over competing measures of transport in ionic solids. However, short coherence times, slow diffusion rates and a small gyromagnetic ratio have, to date, limited their usefulness for measurements of room-temperature transport in solid lithium-ion conductors. Recent developments in quantum control have demonstrated methods for extending the coherence times of dipolar-coupled nuclear spins by several orders of magnitude, into a regime enabling gradient measurements of slow lithium-ion diffusion. This thesis proposes and demonstrates, through the utilization of a dipolar refocusing sequence and a strong pulsed magnetic field gradient, a nuclear magnetic resonance method for the direct measurement of the lithium ion self-diffusion coefficient within room-temperature lithium-ion conductors. Magnetic resonance field gradient measurements derive ensemble transport statistics through observation of the residual phase mismatch following two position dependent phase rotations, implemented as DC pulses of a spatially varying gradient field, separated in time by a transport period. Generating sufficiently fine spatial encodings to be sensitive to slow diffusion has proven challenging in solids where strong relaxation due to the homonuclear dipole-dipole interaction drastically shortens coherence times and thus limits the duration of applied gradient pulses. This study utilizes a magic echo based refocusing sequence to nullify the dominant decoherence mechanism allowing effective gradient pulses on the order of one millisecond. Combined with a custom-built pulsed field gradient, spatial encodings on the order of 1 [mu]m are obtained. For a demonstrative sample, the lithium-ion conductor lithium sulfide is chosen both for its favorable NMR properties and for its role in the recent renewal of interest in nanostructured integration cathode materials. Initial sample characterization reveals two ⁷Li NMR lines distinguished by their static line widths and refocusing behavior. A modified version of the 1D EXSY selective inversion experiment is performed to characterize an exchange process between these two lines and extract their intrinsic spin-lattice relaxation rates. Two stimulated echo diffusion measurements are performed to identify the apparent diffusion coefficients of each line in the presence of exchange. The observed diffusion coefficient of the narrow line is determined to be 2.39 +/- 0.34 . 10-⁸ cm²/s. Diffusive attenuation is not observed for the broad line. These results are analyzed through a two bath exchange model parameterized by the results of the earlier exchange experiments. The influence of exchange on the observed diffusion coefficients is determined to be negligible as diffusion times are limited by the inverse of the exchange rates.
by Kevin D. Krsulich.
Ph. D.
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14

Petit, Dominique, Jean-Pierre Korb, Pierre Levitz, Jean LeBideau y 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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15

Chen, Chao-Hsu. "Atomistic Computer Simulations of Diffusion Mechanisms in Lithium Lanthanum Titanate Solid State Electrolytes for Lithium Ion Batteries". Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc700110/.

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Solid state lithium ion electrolytes are important to the development of next generation safer and high power density lithium ion batteries. Perovskite-structured LLT is a promising solid electrolyte with high lithium ion conductivity. LLT also serves as a good model system to understand lithium ion diffusion behaviors in solids. In this thesis, molecular dynamics and related atomistic computer simulations were used to study the diffusion behavior and diffusion mechanism in bulk crystal and grain boundary in lithium lanthanum titanate (LLT) solid state electrolytes. The effects of defect concentration on the structure and lithium ion diffusion behaviors in LLT were systematically studied and the lithium ion self-diffusion and diffusion energy barrier were investigated by both dynamic simulations and static calculations using the nudged elastic band (NEB) method. The simulation results show that there exist an optimal vacancy concentration at around x=0.067 at which lithium ions have the highest diffusion coefficient and the lowest diffusion energy barrier. The lowest energy barrier from dynamics simulations was found to be around 0.22 eV, which compared favorably with 0.19 eV from static NEB calculations. It was also found that lithium ions diffuse through bottleneck structures made of oxygen ions, which expand in dimension by 8-10% when lithium ions pass through. By designing perovskite structures with large bottleneck sizes can lead to materials with higher lithium ion conductivities. The structure and diffusion behavior of lithium silicate glasses and their interfaces, due to their importance as a grain boundary phase, with LLT crystals were also investigated by using molecular dynamics simulations. The short and medium range structures of the lithium silicate glasses were characterized and the ceramic/glass interface models were obtained using MD simulations. Lithium ion diffusion behaviors in the glass and across the glass/ceramic interfaces were investigated. It was found that there existed a minor segregation of lithium ions at the glass/crystal interface. Lithium ion diffusion energy barrier at the interface was found to be dominated by the glass phase.
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16

Ohlendorf, Gerd, Denny Richter, Jan Sauerwald y Holger Fritze. "High-temperature electrical conductivity and electromechanical properties of stoichiometric lithium niobate". Diffusion fundamentals 8 (2008) 6, S. 1-7, 2008. https://ul.qucosa.de/id/qucosa%3A14152.

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High temperature properties such as electrical conductivity (σ) and resonance behaviour of stoichiometric lithium niobate (LiNbO3) are determined in the temperature range from 20 to 950 °C. The activation energy of the conductivity is found to be 0.9 and 1.7 eV in the temperature range from 500 to 750 °C and from 800 to 950 °C, respectively. During thermal treatments in ambient air up to 950 °C and back, the conductivity remains unchanged at a given temperature, i.e., the crystal is stable under these conditions. The oxygen partial pressure (pO2) dependence of the conductivity shows two distinct ranges. At 750 °C, the property remains unchanged down to 10−15 bar. Below 10−15 bar, the conductivity increases according to σ ~ (pO2)−1/5. Z-cut LiNbO3 plates can be excited to thickness mode vibrations up to at least 900 °C. At this temperature, the quality factor Q is found to be between 30 and 100. As for changes of the conductivity, a decrease of the resonance frequency is observed below 10−15 bar indicating a correlation of both properties. In order to evaluate the lithium evaporation, the crystals are tempered at 900 °C in ambient air for 24 h. A depth profile of the constituents does not indicate lithium loss within the accuracy of the secondary ion mass spectroscopy. The preliminary results underline the potential of stoichiometric LiNbO3 for high-temperature applications and justify its closer investigation.
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17

Fujimura, Koji. "Theoretical Studies of Lithium-Ion Diffusion in LISICON-Type Solid Electrolytes". Master's thesis, 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/180501.

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18

Wiedemann, Dennis, Suliman Nakhal, Stefan Zander y Martin Lerch. "Slowly but Surely—Pathways of Ultraslow Lithium Diffusion in γ-LiAlO2". Diffusion fundamentals 21 (2014) 15, S.1, 2014. https://ul.qucosa.de/id/qucosa%3A32423.

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19

Toyoura, Kazuaki. "Lithium diffusion in graphite intercalation compounds based on transition state theory". 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/136279.

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20

Ruprecht, Benjamin y Paul Heitjans. "Ultraslow lithium diffusion in Li 3 NbO 4 probed by 7 Li stimulated echo NMR spectroscopy". Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-188226.

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21

Epp, Viktor, Christian Brünig, Martin Wilkening, Michael Binnewies y Paul Heitjans. "Lithium diffusion studies of gas-phase synthesized amorphous oxides: an NMR investigation". Diffusion fundamentals 12 (2010) 102, 2010. https://ul.qucosa.de/id/qucosa%3A13913.

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22

Dunford, David V. "Development of diffusion bonding techniques and testing of bonded joints in Al - Li 8090 alloy". Thesis, Imperial College London, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318755.

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23

Ruprecht, Benjamin, Jessica Heine, Martin Wikening, Sylvio Indris, Joseph Wontcheu, Wolfgang Bensch, Thomas Bredow y Paul Heitjans. "Influence of anion substitution on the lithium diffusivity in hexagonal Li x TiS 2-y Se y". Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-188254.

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24

Wilkening, Martin. "Ultralangsame Ionenbewegungen in Festkörpern NMR-spektroskopische Studien an Lithium-Ionenleitern". Berlin Logos-Verl, 2005. http://deposit.ddb.de/cgi-bin/dokserv?id=2686936&prov=M&dok_var=1&dok_ext=htm.

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25

Ciampolillo, Maria Vittoria. "Diffusion of Iron in Lithium Niobate for applications in integrated optical devices". Doctoral thesis, Università degli studi di Padova, 2010. http://hdl.handle.net/11577/3427049.

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In the field of optical signal processing and all-optical integrated devices, photorefractive crystals can be used because of their capability to keep memory of a spatially varying light pattern. Among them, lithium niobate is particularly interesting because its photorefractive response can be improved or inhibited by adding selected dopants: this opens the possibility of producing an integrated device in a lithium niobate single crystal, where each stage has different properties and different functions according to the doping. In particular, a photorefractive stage can be created by doping with Fe, which is known to enhance photorefractive effect. In the context of integrated devices, it is necessary to perform a local doping of lithium niobate with Fe, in order to obtain a suitable substrate for photorefractive recording. This thesis deals with the preparation and characterisation of the locally doped crystal, i.e. with an investigation of the preparation conditions and how they affect the crystal quality. Many characterisation techniques, customary in materials science, such as secondary ion mass spectrometry, spectrophotometry and others, have been used and refined specifically for Fe doped lithium niobate. Besides the practical aim to find the best preparation conditions, many basic properties and features of this material have been investigated, leading to an advance in the knowledge of this material, as well as an advance in the usage of characterisation tools.
Nel campo del trattamento di segnali ottici e dei dispositivi ottici integrati, i cristalli fotorifrattivi sono impiegati per via della loro capacità di mantenere memoria di un pattern di luce. Tra questi, il niobato di litio è particolarmente interessante per via del fatto che la sua risposta fotorifrattiva può essere migliorata o inibita aggiungendo determinati droganti: è quindi possibile produrre, in un cristallo singolo di niobato di litio, un dispositivo integrato in cui ciascuna parte ha differenti proprietà e differenti funzioni a seconda del drogaggio. In particolare, si può realizzare una zona fotorifrattiva drogando con Fe, che come noto aumenta l'eetto fotorifrattivo. Nel contesto dei dispositivi ottici integrati, è necessario drogare localmente con Fe il niobato di litio per ottenere un substrato adatto alla registrazione fotorifrattiva. Questa tesi tratta la preparazione e la caratterizzazione del cristallo drogato localmente, studiando le condizioni di preparazione e come esse in uenzano la qualità del cristallo. Molte tecniche di caratterizzazione abituali in scienza dei materiali, come la spettrometria di ioni secondari, la spettrofotometria ed altre, sono state utilizzate ed affinate specificamente per questo materiale. Accanto all'obiettivo pratico di trovare le migliori condizioni di preparazione, molte proprietà e caratteristiche di base di questo materiale sono state approfondite, progredendo sia nella conoscenza del materiale, sia nell'uso degli strumenti di caratterizzazione.
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26

Petit, Dominique, Jean-Pierre Korb, Pierre Levitz, Jean LeBideau y 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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27

Huynh, Tan-Vu. "Etude par résonance magnétique nucléaire de la mobilité du lithium dans les électrolytes à base de polymères". Thesis, Orléans, 2015. http://www.theses.fr/2015ORLE2054/document.

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Dans les matériaux de batterie, le contrôle de la mobilité des cations lithium est la clé pour repousser les limites de la puissance et des vitesses de charge des batteries. La spectroscopie RMN permet de mesurer les coefficients d’auto-diffusion des espèces porteuses d’un spin nucléaire en utilisant des gradients de champ pulsés qui mesurent le déplacement atomique sur une échelle de 1-2 μm. La relaxation des spins nucléaires `a des champs magnétiques élevés, d’autre part, est régie par les fluctuations des interactions à des fréquences proches de la fréquence de Larmor (fluctuant donc à l’échelle de la nanoseconde), et celles-ci sont généralement liées à des mouvements atomiques sur 1 Å - 1 nm. Dans cette thèse, nous avons mesuré les coefficients d’auto-diffusion et les temps de relaxation du ⁷Li pour deux électrolytes polymères: LiTFSI dans de l’oxyde de polyéthylène (PEO) et dans un copolymère à blocs PS-PEO(LiTFSI)-PS. Les temps de relaxation ont été mesurées à trois champs magnétiques élevés (4.7, 9.4 et 17.6 Tesla) nous permettant d’effectuer une étude simple par relaxométrie des mouvements du Li+ à l’échelle de la nanoseconde. Afin de reproduire l’ensemble des vitesses de relaxation, il est apparu nécessaire d’introduire un modèle simple à deux temps de corrélation. Ceci a montré pour la première fois que la dynamique de lithium dans PS-PEO(LiTFSI)-PS est ralentie par la présence de domaines de PS par rapport au PEO pur avec des longueurs de chaîne similaires. Les résultats sont analysés et comparés à d’autres études basées sur des modèles de dynamique moléculaire ou de diffusion dans les polymères. Une deuxième série d’électrolytes polymères en gel à base de poly(fluorure de vinylidène-co-hexafluoropropylène (PVDF-HFP), PEGM (Poly-éther méthylique d’éthylèneglycol méthacrylate)/PEGDM (Poly diméthacrylate d’éthylèneglycol), et LiTFSI dans les liquides ioniques ont également été étudiés. L’ajout de polymères oxygénés permet d’augmenter la rétention des liquides ioniques, mais ralentit la diffusion expliquant ainsi la baisse de performance de ces batteries à vitesse de charge élevée
In battery materials, the mobility of lithium cations is the key to the limitations in battery power and charging rates. NMR spectroscopy can give access to self-diffusion coefficients of spin bearing species using pulsed field gradients which measure atomic displacement over 1 − 2μm length scales. The relaxation of nuclear spins at high magnetic fields, on the other hand, is governed by fluctuations of NMR interactions resonant with the Larmor frequency, at the nanosecond timescale, and these are usually related to atomic motions over 1 Å - 1 nm. In this thesis, we recorded self-diffusion coefficients and ⁷Li relaxation rates for two polymer electrolytes: LiTFSI in polyethylene oxide (PEO) and in a block-copolymer PS-PEO(LiTFSI)-PS. We first investigated the effect of magic-angle spinning (MAS) on diffusion and relaxation, showing that MAS can help retrieve coefficient diffusion when relaxation is fast and diffusion is slow, and second, that lithium motion is not perturbed by the partial alignment of PEO under MAS induced pressure. The relaxation rates of 7Liwere measured at three high magnetic fields (4.7, 9.4 and 17.6 Tesla) allowing us to perform a simple relaxometry study of Li+motion at the nanosecond timescale. In order to reproduce the transverse and longitudinal relaxation behaviors, it proved necessary to introduce a simple model with two correlation times. It showed for the first time that the lithium dynamics in PS-PEO(LiTFSI)-PSis slowed down by the presence of PS domains compared to the pure PEO with similar chain lengths. The results are analyzed and compared to other studies based on molecular dynamics or physical models of diffusion in polymers. A second series of gel polymer electrolytes based on poly(vinylidene fluoride-co-hexafluoropropylene (PVdF-HFP), PEGM(Poly ethyleneglycol methyl ether methacrylate)/PEGDM (Poly ethyleneglycol dimethacrylate), and LiTFSI in ionic liquids were also studied. Adding oxygenated polymers to increase the retention of ionic liquids slowed the diffusion down and explained why the battery performance was degraded at higher charging rates
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28

Lyons, Daniel J. "Application and Challenges of Neutron Depth Profiling to In-Situ Battery Measurements". The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1610060345543143.

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29

Canales, Sepúlveda Iván Eduardo. "Modeling of diffusion-induced stress in a lithium ion battery using isogeometric analysis". Tesis, Universidad de Chile, 2018. http://repositorio.uchile.cl/handle/2250/164013.

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Ingeniero Civil Mecánico
El desarrollo de baterías de litio de alta potencia es la piedra de tope para el surgimiento de vehículos eléctricos económicos y autónomos, así como para el almacenamiento de electricidad producida por fuentes renovables intermitentes. El principal desafío es la presencia de niveles de deformación y esfuerzo demasiado altos en las zonas activas de los electrodos, a causa del proceso cíclico de intercalación de litio durante la carga y la descarga, llegando incluso a producirse deformación plástica, nucleación de grietas, y fracturas, limitando la vida útil de las baterías. Modelar el fenómeno de la intercalación de litio es complejo, pues los gradientes químicos inducen campos de esfuerzos y, a su vez, los esfuerzos favorecen o dificultan la difusión química a través de la microestructura. Existen modelos que involucran la cinética molecular y la deformación de la microestructura del electrodo. Otros modelos continuos, más sencillos y más fáciles de implementar, han permitido resolver las ecuaciones diferenciales acopladas que dan cuenta del balance termodinámico del sólido involucrado. La mayoría de los modelos están restringidos a geometrías unidimensionales o muy simples. El objetivo de este trabajo es extender el uso de modelos continuos existentes a dos dimensiones, y resolver numéricamente, mediante el análisis isogeométrico, un sistema de ecuaciones diferenciales y acopladas. Con este procedimiento, se espera caracterizar la distribución de esfuerzos y concentratión en una partícula de electrodo de batería, y obtener los niveles de concentración de esfuerzos alrededor de los vacíos y las discontinuidades.
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30

Zaltron, Annamaria. "Local doping of lithium niobate by iron diffusion: a study of photorefractive properties". Doctoral thesis, Università degli studi di Padova, 2011. http://hdl.handle.net/11577/3425330.

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In the last decades the electronic data transmission technology has progressively reached its performance limits and it is nowadays evident that further advances can be achieved only by all-optical signal processing systems. Thus the research in nonlinear optics have been rapidly expanding in the last twenty years, developing many applications of photonics which are now relevant for industrial and consumer markets. In particular, in electro-optic materials the phenomena based on the photorefractive effect are doubtless playing a major role in the building up of optoelectronic signal transmission and processing devices and lithium niobate (LiNbO3) is a promising material due to its high electro-optic and nonlinear optical coefficients. Moreover, lithium niobate offers incredible versatility as substrate for integrated optics, allowing to realize on the same crystal optical elements with different functions, by exploiting various microstructural technologies. This kind of devices require the capability to locally change the physical properties of the material, by doping it with the proper element only in a limited area of the substrate. In particular, it is known that by doping the lithium niobate with iron the photorefractive properties of the material are enhanced, thus to realize an integrated optical system with a photorefractive stage an iron local doping has to be performed. In this work the thermal diffusion process is exploited to realize iron locally doped lithium niobate crystals and the structural and photorefractive properties of the doped layer are studied. In particular it has been designed and built-up a new optical set-up able to investigate only a limited area of the doped layer, thus allowing to relate at each depth the examined iron concentration with the corresponding photorefractive response of the material. In this way it is possible to realize in depth-profiles of the main physical photorefractive parameters involved in the photorefractive effect and physical mechanisms never studied before can be now investigated.
Negli ultimi decenni la tecnologia di trasmissione di dati elettronici ha progressivamente raggiunto i suoi limiti di prestazione ed al giorno d'oggi è evidente che ulteriori sviluppi possono essere raggiunti solo con l'utilizzo di sistemi ottici integrati. Perciò la ricerca relativa all'ottica non lineare ha avuto una rapida espansione negli ultimi ventanni, sviluppando molte applicazioni fotoniche che risultano rilevanti sia per il mercato industriale che per quello privato. In particolare, tra i materiali elettro-ottici i fenomeni che si basano sull'effetto fotorifrattivo stanno senza dubbio avendo un ruolo importante nella realizzazione di dispositivi per la trasmissione e il trattamento di segnali optoelettronici e il niobato di litio (LiNbO3) è un materiale promettente, dati i suoi alti coefficienti elettro-ottici e ottici non lineari. Inoltre il niobato di litio offre un incredibile versatilità come substrato per ottiche integrate, permettendo di realizzare sullo stesso cristallo elementi ottici con differenti funzioni, sfruttando varie tecnologie di microstrutturazione. Questo tipo di dispositivi richiede la capacità di cambiare localmente le proprietà fisiche del materiale, drogandolo con un opportuno elemento su una regione limitata del substrato. In particolare, è noto che drogando il niobato di litio con ferro le proprietà fotorifrattive del material vengono notevolmente migliorate, così per realizzare un sistema ottico integrato che presenti uno stadio fotorifrattivo si deve realizzare un drogaggio locale con ferro. In questo lavoro il processo di diffusione termica è sfruttato per realizzare cristalli di niobato di litio drogati localmente con ferro e sono studiate le proprietà strutturali e fotorifrattive dello strato drogato. In particolare è stato sviluppato e costruito un apparato ottico in grado di investigare solo un'area limitata dello strato drogato, permettendo in tal modo ad ogni profondità all'interno della zona drogata di mettere in relazione la concentrazione di ferro esaminata con la corrispondente risposta fotorifrattiva del materiale. In questo modo è possibile realizzare profili in profondità delle principali grandezze fisiche coinvolte nell'effetto fotorifrattivo e meccanismi fisici mai studiati prima possono essere ora investigati.
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31

Ruprecht, Benjamin y Paul Heitjans. "Ultraslow lithium diffusion in Li 3 NbO 4 probed by 7 Li stimulated echo NMR spectroscopy". Diffusion fundamentals 12 (2010) 100, 2010. https://ul.qucosa.de/id/qucosa%3A13912.

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32

Brenet, Gilles. "Simulations multi-échelles de la cinétique dans les matériaux pour l'énergie : le silicium solaire et les composés d'intercalation pour les batteries lithium-ions". Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAY028/document.

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La production et le stockage de l'énergie est un grand défi de notre société. Les propriétés de certains matériaux sont dues principalement aux défauts qu'ils contiennent. Afin d'améliorer les matériaux que nous utilisons, il est nécessaire de pouvoir les modéliser. Ce travail est centré sur l'étude de divers défauts dans deux matériaux, le silicium et le graphite lithié. Au travers de la simulation multi-échelles, nous modélisons les défauts et leur cinétique, afin de pouvoir prédire leur formation mais aussi leur vieillissement.La première partie est centrée sur les différentes méthodes que nous avons employées. Ces méthodes sont réparties dans trois catégories, qui donnent accès chacune à une échelle de simulation. En démarrant sur des modèles électroniques et des simulations textit{ab initio}, nous avons pu mener des simulations atomistiques grâce à des algorithme stochastiques. Ces résultats ont ensuite mené vers des modèles macroscopiques, afin de pouvoir les comparer aux résultats expérimentaux.La seconde partie développe nos analyse sur les défauts ponctuels dans le silicium : carbones, oxygènes, lacunes et interstitiels. Ces défauts se regroupent et forment des complexes dans le silicium irradié. En analysant le comportement de ces complexes à l'échelle atomique, nous avons pu construire un modèle permettant de simuler la cinétique de multiples défauts, ainsi que la chaîne de réactions, sur plusieurs dizaines d'années. Ainsi, il est possible de déterminer les conditions permettant un meilleur contrôle de la formation et du vieillissement des complexes.La dernière partie présente l'analyse du graphite lithié. Ce composant de base des batteries lithium-ion est du graphite dans lequel s'intercale des atomes de lithium lors de la charge. La cinétique de la charge prédit le regroupement des atomes en îles, qui se déplacent lors de la charge. La propagation des atomes de lithium des bords de l'électrode vers le centre du graphite est également analysé
Energy production and storage is a big challenge in our society. The properties of some materials are mainly due to the defects therein. To improve the materials we use, it is necessary to be able to model them. This work focuses on the study of various defects in both materials, silicon and lithium graphite. Through the multi-scale simulation, we model the defects and their kinetics in order to predict their formation but also aging.The first part focuses on the various methods we used. These methods are divided into three categories, each providing access to a simulation scale. By starting on electronic models with textit{ab initio} simulations, we were able to simulate defects behavior with atomistic simulations using stochastic algorithm. These results then led to macroscopic models, in order to compare our simulations with the experimental results.The second part develops our analysis of point defects in silicon: carbon, oxygen, vacancies and interstitials. These defects gather and form complexes in the irradiated silicon. By analyzing the behavior of these complexes at the atomic scale, we could build a model to simulate the kinetics of multiple defects, and the reaction chain, over several decades. Thus, it is possible to determine the conditions for greater control of the formation and aging of various complexes.The last part presents the analysis of lithium graphite. This component of lithium-ion batteries is made of graphite in which lithium atoms intercalate during charging. The kinetics of the charging predicts the grouping of lithium atoms in islands, which move during charging. The lithium atoms diffusion from the edges of the electrode towards the center of the graphite is also analyzed
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33

Ruprecht, Benjamin, Jessica Heine, Martin Wikening, Sylvio Indris, Joseph Wontcheu, Wolfgang Bensch, Thomas Bredow y Paul Heitjans. "Influence of anion substitution on the lithium diffusivity in hexagonal Li x TiS 2-y Se y". Diffusion fundamentals 12 (2010) 106, 2010. https://ul.qucosa.de/id/qucosa%3A13915.

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Islam, Mazharul M. y Thomas Bredow. "Li Diffusion in Various Polymorphs of LiTiS2: Insights from Theory". Diffusion fundamentals 21 (2014) 12, S.1, 2014. https://ul.qucosa.de/id/qucosa%3A32418.

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In the present contribution, the stoichiometric and defect properties in 1T, c and 3R polymorphs of lithium titanium disulphide (LixTiS2) are investigated theoretically with periodic quantum chemical methods.
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35

Heine, Jessica [Verfasser]. "NMR- und impedanzspektroskopische Untersuchungen an Lithium-Ionenleitern mit eingeschränkter Dimensionalität der Diffusion / Jessica Heine". Hannover : Gottfried Wilhelm Leibniz Universität Hannover, 2020. http://d-nb.info/1219652202/34.

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36

Witt, E., J. Rahn, H. Schmidt, S. Nakhal, M. Lerch, C. V. Chandran y P. Heitjans. "Nuclear Magnetic Resonance and Impedance Spectroscopy Studies on Lithium Ion Diffusion in γ-LiAlO2". Diffusion fundamentals 21 (2014) 27, S.1, 2014. https://ul.qucosa.de/id/qucosa%3A32437.

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37

Moulin, Béatrice. "Spectrométrie de diffusion Raman pulsée pour les hautes températures : application à LiNbO3 et d'autres oxydes modèles". Orléans, 2002. http://www.theses.fr/2002ORLE2050.

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On présente un système de spectroscopie de diffusion Raman pulsée pour réduire l'émission thermique lors de mesures à haute température. Deux voies de détection pulsée ont été utilisées : un commutateur de Pockels et un détecteur ICCD. L'ensemble a été testé sur des oxydes modèles : l'alumine et la zircone jusque vers 2000ʿC. Le cas du niobate de lithium liquide a été considéré plus en détails. Au dessus de la température de fusion (Tf = 1260ʿC), des inclusions solides apparaissent. Les caractérisations Raman et de diffraction X montrent qu'il s'agit de LiNbO3 solide, probablement ferroélectrique. Un changement d’environnement du niobium pourrait être à l'origine de ce phénomène.
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38

Melkior, Thierry. "Etude méthodologique de la diffusion de cations interagissant dans des argiles : application : mise en œuvre expérimentale et modélisation du couplage chimie-diffusion d'alcalins dans une bentonite synthétique". Châtenay-Malabry, Ecole centrale de Paris, 1999. http://www.theses.fr/1999ECAP0652.

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Ce travail entre dans le cadre du projet de stockage souterrain de déchets radioactifs. Il concerne l'étude de la migration de radionucléides à travers des argiles. Le phénomène de transport considéré comme majoritaire dans ces matériaux étant la diffusion, des expériences de diffusion sont menées pour caractériser le transfert de radioéléments. La durée de ces essais est particulièrement longue, lorsque les espèces considérées présentent des affinités chimiques importantes avec le matériau. Une solution alternative consiste à estimer d'une part les propriétés de diffusion à l'aide de mesures effectuées avec un traceur de l'eau (espèce non réactive), les interactions chimiques étant d'autre part déduites d'expériences réalisées en tubes à essais. Ces données sont alors utilisées pour simuler le transfert de ces éléments à l'aide d'outils numériques permettant de traiter le couplage chimie-diffusion. L'objectif de cette thèse est de tester la validité d'une telle approche, en comparant les simulations aux résultats d'expériences de diffusion réalisées avec des espèces inter agissantes. Le sujet est envisagé dans le cas du transfert de césium, lithium et sodium à travers une bentonite sodique. Les expériences de diffusion sont réalisées par la technique de la through-diffusion. La comparaison entre l'expérience et le modèle montre que la méthodologie proposée tend à sous-estimer la propagation des espèces considérées. Les écarts pourraient être dus à la présence de diffusion surfacique et à la diminution de l'accessibilité aux sites de fixation entre les suspensions d'argile en tubes à essais d'une part et les échantillons compactes d'autre part. Par ailleurs, une étude de l'influence des dispositifs expérimentaux utilisés pour réaliser les essais de diffusion sur les mesures a montré qu'ils doivent être pris en compte lors de l'interprétation des données expérimentales. Un modèle spécifique a donc été développé à l'aide du code de calcul CASTEM 2000
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39

Fei, Yao. "Carbon-Based Nanomaterials as an Anode for Lithium Ion Battery". Palaiseau, Ecole polytechnique, 2013. http://pastel.archives-ouvertes.fr/docs/00/96/79/13/PDF/20130912_Fei_YAO_thesis_Ecole_submission.pdf.

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Dans ce travail de thèse, nous avons exploré l'utilisation des nanomatériaux à base de carbone comme anode pour les batteries lithium-ion. Par rapport aux matériaux d'anode classiques qui sont de type carbone graphitique a des tailles de grains de l'ordre du micromètre, les matériaux de carbone de taille nanométrique présentent un grand potentiel non seulement pour l'application pratique en tant que matériau d'anode, mais aussi du point de vue de la science fondamentale car permettent l'exploration fine des phénomènes de diffusion des ions lithium. Dans le cadre de l'application pratique, nous avons exploré les nanofibres unidimensionnelles de carbone (CNF) en tant que matériau d'anode. Cette structure d'anode comporte un substrat métallique comme collecteur de courant mais n'avons pas utilisé des liants ce qui bénéficie a la stabilité à long terme. Pourtant, la densité d'énergie que nous avons obtenu était encore limitée à 370 mAh /g similaire à celle du carbone conventionnel. Afin d'améliorer la capacité des nanofibres de carbone bruts, nous les avons recouverts de silicium (par dépôt électrochimique), un matériau d'insertion de lithium avec une bien plus importante capacité de stockage. Le tapis hybrides Si / CNF ont permis d'améliorer nettement la capacité des matériaux de carbone jusqu'à deux fois de plus pour la plupart des cas. Du point de vue des études fondamentales, le graphène matériau bidimensionnel, a été synthétisé par dépôt chimique en phase vapeur (CVD) et utilisé comme un support pour mettre en évidence les chemins de diffusion des ions lithium. Par rapport à du graphite classique qui contient à la fois les deux plans de type basal et prismatique, seulement un plan basal bien défini et d'une grande surface spécifique peut être réalisé dans le cas du graphène. Nous avons découvert que la réaction électrochimique a l'électrode (substrat / graphène) est non seulement liée au nombre de couches de graphène mais s'appuie également sur la présence de défauts dans le plan de graphène. Combinant les résultats expérimentaux et les calculs de théoriques, nous avons pu prouver que le plan basal empêche la diffusion des ions de lithium avec une hauteur de barrière de diffusion élevé, alors que les divacancies et les défauts d'ordre supérieur peuvent constituer des raccourcis pour la diffusion des ions de lithium
In this thesis work, carbon-based nanomaterials using as an anode for lithium ion battery have been generally investigated. Compared to typical micron-sized carbon materials, nanosized carbon materials exhibited great potentials not only in practical anode application but also in the fundamental science exploration of Li ion diffusion. In the case of practical application, one dimensional carbon nanofibers (CNFs) fabricated by electrospinning was prepared for anode material. The structure involves neither a metal substrate nor binders and therefore eventually benefited the capacity and long term stability. Yet, the energy density is still limited to 370 mAh/g of conventional carbon. In order to improve the capacity of raw carbon nanofibers, silicon, a high Li storage material, was incorporated by electrochemical deposition. The resulted Si/CNF mat improved clearly the capacity of carbon materials more than twice for most of cases. In the case of fundamental study, chemical vapor deposition (CVD)-synthesized two dimensional graphene was chosen to be a media to reveal the diffusion pathways of Li ion. Compared to typical graphite which contains both basal and edge planes, a well defined basal plane with large area can be realized in graphene to provide a comprehensive picture of lithium diffusion mechanism. We have discovered that electrochemical reaction of electrode (substrate/graphene) not only is related to the number of graphene layers but also relies on the defect sites on the basal plane of graphene. Combing the experimental results and density functional theory calculations, we proved that basal plane hindered lithium ion diffusion with a high diffusion barrier height, whereas divacancies and higher order defects can be shortcuts for lithium ion diffusion
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40

Chaloux, Sophie. "Stabilité interfaciale d'électrolytes binaires et ternaires face au lithium et coefficient de diffusion de l'ion lithium dans des cathodes d'oxydes mixtes LiNi[indice](1-y)Co[indice]yO[indice]2". Sherbrooke : Université de Sherbrooke, 2000.

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41

Volgmann, K., V. Epp, P. Bottke, C. V. Chandran, S. Nakhal, M. Lerch, M. Wilkening y P. Heitjans. "Multinuclear Solid-State NMR Study of Local Structure and Dynamics in Li0.7Nb3S4". Diffusion fundamentals 21 (2014) 24, S.1, 2014. https://ul.qucosa.de/id/qucosa%3A32434.

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42

Wiemhöfer, Hans-Dieter. "Lithium Ion Transport in Polymer Electrolyte Films for Solid State Batteries – An Overview on Concepts, Techniques and Results". Diffusion fundamentals 21 (2014) 7, S.1, 2014. https://ul.qucosa.de/id/qucosa%3A32399.

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43

Sonntag, Iris. "Die Verteilung von Lithium, Beryllium und Bor in Phänokristallen von kalkalkalischen Gesteinen am Beispiel der Insel Nisyros (Ägäis)". [S.l. : s.n.], 2007. http://nbn-resolving.de/urn:nbn:de:bsz:16-opus-81203.

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44

Grisard, Arnaud. "Lasers guides d'onde dans le niobate de lithium dopé erbium". Phd thesis, Université de Nice Sophia-Antipolis, 1997. http://tel.archives-ouvertes.fr/tel-00089120.

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Le niobate de lithium dopé à l'erbium permet de tirer parti des propriétés optiques des ions terre rare et du fort coefficient électro-optique de la matrice. Il constitue ainsi un matériau prometteur pour la réalisation de lasers déclenchés monolithiques émettant vers 1,5 µm. En configuration guidée, l'obtention d'impulsions à forte puissance crête est en particulier envisageable à partir d'un pompage par diode laser du commerce et avec de faibles tensions de commande.
Dans cette perspective, un mécanisme prépondérant de réduction du gain aux fortes concentrations de dopant, caractéristique des cristaux dopés dans la masse, a été identifié et une méthode originale développée pour évaluer simplement ses effets de façon quantitative.
Ce mémoire souligne l'excellent accord entre les prévisions théoriques du modèle d'amplification optique mis en place puis adapté au cas de guides monomodes et les mesures réalisés sur les composants fabriqués dans le même temps par diffusion de bandes de titane dans des substrats dopés dans la masse et en surface.
Ceci a permis d'observer pour la première fois l'effet laser en continu dans des guides d'onde sur niobate de lithium dopé à l'erbium dans la masse et pompés par une diode à 1,48 µm. L'intégration de modulateurs électro-optiques a également conduit à l'observation d'impulsions déclenchées. Pour l'instant limitées par la puissance de pompe disponible, elles devraient pouvoir atteindre plusieurs centaines de watts de puissance crête avec des durées de quelques nanosecondes.
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45

Rycroft, Stuart N. "Small angle neutron scattering study of diffusion of oxygen in silicon, the nickel superalloy SRR99 and aluminium lithium alloys". Thesis, University of Reading, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389641.

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46

Volgmann, Kai Tristan [Verfasser]. "Untersuchung der Diffusion von Lithium- und Natrium-Ionen in Festkörpern unter Berücksichtigung der Dimensionalität des Kristallgitters / Kai Tristan Volgmann". Hannover : Technische Informationsbibliothek (TIB), 2016. http://d-nb.info/1122119372/34.

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47

Wilkening, Martin. "From Ultrafast to Extremely Slow Li Ion Dynamics in (Nano-)crystalline Solids ― Dimensionality Effects and Structural Disorder". Diffusion fundamentals 21 (2014) 8, S.1-2, 2014. https://ul.qucosa.de/id/qucosa%3A32400.

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48

Wagner, Reinhard, Daniel Rettenwander, Maria Maier, Walter Schmidt, Julia Langer, Martin Wilkening y Georg Amthauer. "Synthesis of Coarse-grained Garnet-type Li-ion Conductor Li7-3x(Al/Ga)xLa3Zr2O12 and its Li-ion Dynamics". Diffusion fundamentals 21 (2014) 9, S.1-2, 2014. https://ul.qucosa.de/id/qucosa%3A32401.

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Strŭzik, M., J. L. M. Rupp, S. Buecheler y M. Rawlence. "Physical and Electronic Characterization of Li7La3Zr2O12 Doped Thin Films". Diffusion fundamentals 21 (2014) 10, S.1, 2014. https://ul.qucosa.de/id/qucosa%3A32403.

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50

Hüger, Erwin, Bujar Jerliu, Lars Dörrer, Michael Bruns, Harald Schmidt y Günter Borchardt. "A combined SIMS and XPS Study on the Mechanism of Amorphous Silicon Electrode Lithiation in Li-Ion Batteries". Diffusion fundamentals 21 (2014) 17, S.1, 2014. https://ul.qucosa.de/id/qucosa%3A32426.

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