Dissertations / Theses on the topic 'Phase diagram'
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Fallas, Chinchilla Juan Carlos. "Pressure-temperature phase diagram of LiA1H₄." abstract and full text PDF (UNR users only), 2009. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1464434.
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Azevedo, Cesar R. de Farias. "Phase diagram and phase transformations in Ti-Al-Si system." Thesis, Imperial College London, 1996. http://hdl.handle.net/10044/1/1278.
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Prins, Sara Natalia. "The AI-Pt-Ru ternary phase diagram." Diss., Pretoria : [s.n.], 2003. http://upetd.up.ac.za/thesis/available/etd-09192005-163724/.
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Attwood, Brian Christopher. "Global phase diagram for monomer/dimer mixtures." NCSU, 2001. http://www.lib.ncsu.edu/theses/available/etd-20011012-113555.
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The objective of this thesis is to calculate the global phase diagram predicted by the Generalized Flory Dimer equation of state for mixtures of square-well monomers and dimers. Towards that goal, we first extend the Generalized Flory Dimer (GFD) theory for hard sphere monomer/dimer mixtures to square-well monomer/dimer mixtures. Theoretical predictions for the compressibility factor as a function of volume fraction are compared to discontinuous molecular dynamic simulation results on monomer/dimer mixtures at well depth ratios 0.5 - 1.5 and dimer mole fractions 0.111 - 0.667 and on monomers/8-mer mixtures at well depth ratios 0.5 - 1.5. Agreement is found generally to be good and consistent with the agreement obtained when the GFD theory is applied to other square-well systems. Next we calculate the GFD predicted global phase diagram for square-well monomer/dimer mixtures using a brute force method. The locus of critical points in the direction implies that monomer/dimer systems have a greater tendency towards liquid-liquid immiscibility in our system than in monomer/monomer systems.
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Huang, Gang 1971. "Phase diagram for liquid crystalline polymerpolycarbonate blends." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33973.
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Blends containing a thermotropic liquid crystalline polymer and an engineering thermoplastic polymer have recently received considerable attention, because liquid crystalline polymers display low melt viscosity, excellent chemical resistance, thermal stability and mechanical performance. A novel mechanism to form binary polymer blends is through phase separation by spinodal decomposition in the unstable region of the phase diagram. The overall objective of this work is to investigate the effects of thermally induced phase separation by spinodal decomposition on the morphology development of liquid crystalline polymer/polycarbonate blends and to obtain a thermodynamic binary phase diagram. The blends were obtained using a twin-screw extruder at various processing melt temperatures. To study miscibility of the blends and the resulting morphology, techniques such as differential scanning calorimetry and scanning electron microscopy were used. The liquid crystalline polymer/polycarbonate blend undergoes phase separation during thermally induced spinodal decomposition exhibiting a miscibility window reminiscent of a lower critical solution temperature. The blend is found to be miscible, when blend Tg slightly decreases. On the other hand, the blend is found to be immiscible as blend Tg increases. A thermodynamic two-phase transition curve phase diagram was obtained using an innovative practical experimental technique in conjunction with twin screw extrusion and scanning electron microscopy.
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Duncan, Graham Kirk. "Phase diagram studies of the beta-aluminas." Thesis, University of Aberdeen, 1985. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=201758.
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Chang, Fwu-Ranq. "Optimal Growth and Impatience: A Phase Diagram Analysis." 名古屋大学大学院経済学研究科附属国際経済政策研究センター, 2004. http://hdl.handle.net/2237/11954.
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Assawasunthonnet, Wathid. "Second order critical point in QCD phase diagram." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/51611.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2009.Includes bibliographical references (p. 57).
In this thesis I explore the theoretical model based on Asakawa and Nonaka's idea[l]. I start by arguing that the critical point of the QCD phase diagram is second order and belongs to the three dimensional Ising model universality class. Then the singular part of the equation of state is derived. The singular part and non-singular part equation of state are glued together to find the general form of the equation of state. This equation of state includes the critical point. With this equation of state, we construct the isentropic trajectories. The pathology of these trajectories is discussed. Moreover the validation of the signature of the critical point suggested by Asakawa and Nonaka is also discussed.
by Wathid Assawasunthonnet.
S.B.
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Mikula, Hynek. "Fázový diagram chladiva LiF-NaF-KF." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-374735.
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In introduction this graduation theses discource about phase diagrams and thein fission. Next part is about concrete phase diagrams NaF – KF, NaF – LiF, KF – LiF. Their determination trough use of cooling surves and their specification trough use of numerical method. Conclusion contains proposal of method for concrete phase diagram of NaF – KF – LiF.
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Sevelev, Maxime. "Phase diagram, jamming and glass transitions in the non-convex perceptron." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS331.
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Cette thèse de doctorat traite du « modèle de perceptron sphérique », un modèle simple et exactement soluble qui présente un comportement visqueux et d'encombrement qui a été généralisé aux valeurs négatives du paramètre de produit scalaire κ. Le problème classique d'apprentissage par machine qui consiste en la classification des motifs aléatoires par le perceptron fait partie des problèmes de satisfaction des contraintes (PSC) convexes. Même quand le « paramètre de stabilité » du modèle κ devient négatif, le problème reste toujours correctement posé et peut être interprété comme le problème de placement des particules sur une sphère N-dimensionnelle en évitant les obstacles placés au hasard. Dans ce cas, le PSC correspondant n'est pas convexe. Cette thèse étudie le problème en détail dans le domaine non convexe. Une étude systématique est rendue possible en faisant correspondre à un problème de satisfaction de contraintes un problème d'optimisation sur le même support, mais doté d'un Hamiltonien (fonction de coût) qui mesure les violations des contraintes en fonction de la configuration du système. Le lien entre le PSC aléatoire et la phénoménologie vitreuse en physique est bien connue et a été explorée en détail pour les modèles à variables discrètes. La présence de variables continues dans le modèle de perceptron (sphérique) nous permet de dévoiler, en PSC aléatoire, la transition caractéristique SAT/UNSAT où le système subit une transition du régime satisfaisable (dans lequel l'état fondamental possède une énergie nulle) à celui insatisfaisable (dans lequel l'état fondamental possède une énergie positive). Cette transition de phase peut également être interprétée comme une transition d'encombrement similaire à celles démontrées par les modèles des sphères sans friction. La simplicité du modèle étudié permet de trouver exactement son diagramme de phase à température zéro en fonction des deux paramètres de contrôle: la densité des obstacles et leur taille. Ainsi identifiée, la transition d'encombrement est complètement caractérisée dans le présent document. Sont également étudiées en détail de diverses phases vitreuses de caractère stable et marginalThis thesis treats the «spherical perceptron model», a simple exactly solvable model for glassy behavior and jamming suitably generalized to negative values of scalar product parameter κ. The classical machine-learning problem of random pattern classification by the perceptron is a convex constraint satisfaction problem (CSP). Even when the «stability parameter» κ of the model becomes negative, the problem still make sense and can be interpreted as the problem of particles on an N-dimensional sphere trying to avoid randomly placed obstacles. In this case, the corresponding CSP is non-convex. This thesis studies the problem in detail in the non-convex domain. Systematic study is made possible by assigning to a constraint satisfaction problem its corresponding optimization version endowed with a Hamiltonian function (cost function) quantifying the violations of the constraints, as a function of the system's configuration. The connection between random CSP and glassy phenomenology in physics is well known and has been explored in detail for models with discrete variables. The presence of continuous variables in the (spherical) perceptron model enables us to unveil, in random CSP, the characteristic SAT/UNSAT transition where the system transits from the satisfiable regime (where the ground state has zero energy) to the unsatisfiable one (where the ground state energy is positive). This phase transition can also be interpreted as a jamming transition similar to the one that exhibit models with frictionless spheres. The simplicity of the considered model allows the exact determination of the zero temperature phase diagram as a function of the control parameters: the density of obstacles and their size. In the present thesis, the jamming transition thus identified is completely characterized and several glass phases of stable and marginal character are studied in detail
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Yamamoto, Masahiro, Hiromichi Ohta, and Kunihito Koumoto. "Thermoelectric phase diagram in a CaTiO3- SrTiO3 - BaTiO3 system." American Institute of Physics, 2007. http://hdl.handle.net/2237/8769.
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Günther, Jana [Verfasser]. "Lattice investigations of the QCD phase diagram / Jana Günther." Wuppertal : Universitätsbibliothek Wuppertal, 2017. http://d-nb.info/1128844818/34.
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Steinert, Thorsten [Verfasser]. "The QCD phase diagram within effective models / Thorsten Steinert." Gießen : Universitätsbibliothek, 2018. http://d-nb.info/116167036X/34.
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Ubbens, Menke Ubbo Heert. "The superconducting phase diagram of the t-J model." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/32130.
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Epifano, Enrica. "Study of the U-Am-O ternary phase diagram." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLX084/document.
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Les isotopes de l’Américium sont les principaux contributeurs à la radioactivité des déchets nucléaires. Parmi les scénarios pour diminuer la toxicité des déchets, la transmutation dans les réacteurs à neutrons rapides utilisant des pastilles d’oxyde mixte (U,Am)O2 est une voie prometteuse. Dans ce cadre, la connaissance des propriétés thermodynamiques du système U-Am-O est essentielle pour prédire le comportement des pastilles (U,Am)O2 en conditions nominale et accidentelle. Cette thèse est dédiée à l’étude expérimentale d’oxydes mixtes (U,Am)O2 dans une large gamme de composition (7,5 % at. ≤ Am/(Am+U) ≤ 70 % at.). L’objectif est d’acquérir des données pour développer un modèle thermodynamique avec la méthode semi-empirique CALPHAD. Les résultats peuvent être classés en trois catégories : données structurales, données de diagramme de phase et données thermodynamiques. Pour la modélisation thermodynamique d’un système ternaire, l’optimisation des sous-systèmes binaires est nécessaire. Comme des questions restaient en suspens sur le système Am-O, le diagramme de phase Am-O a tout d’abord été étudié par diffraction des rayons X à haute température. L’existence d’un domaine de composition de la phase bcc AmO1.61 a été mis en évidence et la lacune de miscibilité dans la phase fluorite, proposée dans la littérature, n’a pas été confirmée. Grâce à ces nouveaux résultats, le modèle CALPHAD de Gotcu et al a été modifié. Dans une deuxième étape, des analyses structurales des dioxydes (U,Am)O2±x ont été effectuées par DRX, XAS et spectroscopie RAMAN. La DRX a permis de confirmer que tous les échantillons sont constitués d’une seule phase de structure fluorite. Le rapport O/M (avec M=U+Am) mesuré à température ambiante est inférieur à 2 ; la stabilité de l’Américium trivalent Am3+ a été mise en évidence. Celle-ci induit l’oxydation partielle de l’U4+ en U5+. Cette distribution de charge s’accompagne par la formation de défauts de l’oxygène complexes dans la structure fluorite. Lors de l’étude par DRX HT des oxydes mixtes sous air, il a été montré que la présence d’Am3+ stabilise la phase fluorite par rapport aux oxydes plus riches en oxygène (U4O9, U3O8). De nouvelles données de diagramme de phase ont été obtenues : des conodes dans les domaines biphasés M4O9-M3O8 and MO2+x-M3O8 et la solubilité de l’Américium dans les oxydes M4O9 et M3O8. L’étude du diagramme de phase U-Am-O a été poursuivie par la détermination des températures de solidus/liquidus des oxydes mixtes par une technique de chauffage laser, sous argon et sous air, et par la caractérisation des échantillons après fusion par SEM et XAS. La température de fusion des oxydes mixtes diminue avec une teneur croissante d’Américium (Am/(Am+U)) et d’oxygène (O/(Am+U)). Finalement, les propriétés thermodynamiques des oxydes (U,Am)O2±x ont été mesurées : les incréments enthalpiques par calorimétrie de chute et les pressions partielles des espèces gazeuses par Spectrométrie de Masse couplée à une cellule de Knudsen (KEMS). Une contribution d’excès de la capacité calorifique a été observée à haute température, attribuée à la réduction des oxydes (avec formation de lacunes d’oxygène). Les résultats de KEMS ont permis de déterminer une composition congruente de vaporisation à 2300 K, pour un rapport Am/(Am+U) de 0,6 et un rapport O/(U+Am) inférieur à 1,9. Finalement, la modélisation thermodynamique du système U-Am-O par la méthode CALPHAD a été abordée par la description de la phase fluorite. Un bon accord est obtenu entre le modèle et les données de potentiel d’oxygène pour l’oxyde (U0.5Am0.5)O2±x et de distribution des cations. De plus, le modèle permet de reproduire de façon satisfaisante les données de KEMS. En perspective de ce travail, la modélisation thermodynamique du ternaire sera étendue à la description des équilibres de phase mettant en jeu les oxydes M4O9, M3O8 et la phase liquideAmericium isotopes are the main contributors to the long-term radiotoxicity of the nuclear wastes, after the plutonium extraction. Among the reprocessing scenarios, the transmutation in fast neutron reactors using uranium-americium mixed oxide (U,Am)O2±x pellets seems promising. In this frame, the knowledge of the thermodynamics of the U-Am-O ternary system is of essential for the prediction of the behavior of (U,Am)O2 pellets and their possible interaction with the cladding, under normal and accidental conditions. This thesis is dedicated to the experimental investigation of U-Am mixed oxides on a wide range of Am contents (7.5 at.% ≤ Am/(Am+U) ≤ 70 at.%), with the aim to collect data for developing a thermodynamic model based on the semi-empirical CALPHAD method. The obtained results can be classified in three categories: structural, phase diagram and thermodynamic data. For the thermodynamic modeling of the ternary system, the assessment of the binary sub-systems is first required. As open questions still existed on the Am-O system, a first part of the work was dedicated to the study of the Am-O phase diagram by high-temperature (HT) XRD. The existence of a composition range of the bcc AmO1.61 phase was highlighted and the miscibility gap in the fluorite phase, proposed in the literature, was not found. Thanks to the new experimental data, the existing CALPHAD model of Gotcu et al. was modified. In a second step, structural investigations were performed on synthesized (U,Am)O2±x dioxides by coupling XRD, XAS and Raman spectroscopy. For all the compositions, the XRD confirmed the formation of a single fluorite structure. The O/M ratio (with M=U+Am) at room temperature was determined to be lower than 2; the stability of trivalent americium Am3+ in the dioxide solid solution was highlighted, which induces a partial oxidation of uranium from U4+ to U5+. This charge distribution, peculiar for a dioxide, is accompanied by the formation of complex oxygen defects in the fluorite structure. By a HT-XRD investigation of the mixed oxides under air combined with XAS characterization of the oxidized samples, it was shown that the presence of Am3+ leads to a stabilization of the dioxide fluorite phase toward the formation of oxides richer in oxygen, in comparison to the U-O system. New phase diagram data were obtained in the oxygen rich region at 1470 K: tie-lines in the M4O9-M3O8 and MO2+x-M3O8 domains were determined and the solubility of americium in the M4O9 and M3O8 oxides was estimated. The investigation of the U-Am-O phase diagram continued at higher temperature with the study of the solidus/liquidus transitions using a laser-heating technique, under argon and air, and post-melting characterizations conducted by SEM and XAS. The melting temperature of Am-U dioxides decreases with the increase of both the Am/(Am+U) and O/M ratios. Finally, thermodynamic properties of the U1-yAmyO2±x oxides were measured: enthalpy increments using drop calorimetry, partial vapor pressures by Knudsen cell effusion mass spectrometry (KEMS). An excess contribution to the heat capacity at high temperature was observed and this was attributed to the reduction of the dioxides at high temperature (formation of oxygen vacancies). The KEMS results lead to determine the congruent vaporization composition at 2300 K, for a Am/(Am+U) ratio of 0.6 and an O/M ratio lower than 1.9. Finally, the CALPHAD thermodynamic assessment of the U-Am-O system was started, by focusing the attention on the modelling of the fluorite phase. A good agreement between the model and the oxygen potential data for (U0.5Am0.5O2±x) and the cation distribution was achieved. Furthermore, the model is able to satisfactorily reproduce the KEMS data and hence the equilibrium between the dioxide and gas phase. For the perspectives of this work, the optimization of the thermodynamic model should be extended to describe the phase equilibria involving the M4O9, M3O8 oxides and the liquid phase
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Maelger, Jan. "Perturbative perspectives on the Phase diagram of Quantum ChromoDynamics." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLX050/document.
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L'étude du diagramme des phases de la Chromodynamique Quantique (QCD) et des transitons associées (déconfinement et restoration de la symétrie chirale) représentent des défis majeurs de la Physique moderne et nombreuses sont les approches théoriques qui visent à en sonder les multiples facettes. Du fait de l'intensité de l'interaction forte dans les régimes d’énergie pertinents pour les transitions susmentionnées, ces approches sont en général de nature non-perturbative, la théorie des perturbations étant réputée inapplicable à ces échelles. Il est, cependant, bien établi que le point de départ de la théorie usuelle des perturbations, basée sur la procédure de fixation de jauge de Faddeev-Popov, est ambigu à ces échelles (ambiguïté de Gribov). Dans ce contexte, une approche perturbative modifiée, basée sur le Lagrangien de Curci et Ferrari, a été proposée, via l’ajout phénoménologique d'un terme de masse effectif pour le gluon en jauge de Landau. Cette approche a été testée avec succès, notamment dans sa capacité à reproduire les fonctions de corrélation de la théorie Yang-Mills (et QCD dans la limite de quarks lourds) et la thermodynamique à temperature et potentiel chimique non nuls.Dans cette thèse, nous avons testé la robustesse de ces résultats en évaluant la structure de phase de la QCD avec quarks lourds au deuxième ordre de la théorie des perturbations dans le modèle de Curci-Ferrari et en comparant nos résultats à ceux d'approches nonperturbatives. Nos résultats indiquent que, dans ce régime de quarks lourds, le diagramme de phases est contrôlée perturbativement. Nous avons égalementétendu notre étude au cas de la QCD avec quarks légers en utilisant un schéma de resommation qui exploite la présence de petits paramètres dans le régime infrarouge de la QCD. Dans le secteur des quarks, cette démarche donne lieu à la resommation des fameux diagrammes dits "arc-en-ciel”. Ici, nous généralisons ce formalisme à temperature et densité non nulles et en presence d'un champ de fond gluonique. Nous réalisons une toute première étude qualitative des prédictions du modèle CF concernant l’existence possible d’un point critique dans le diagramme de phases de QCD sur la base d’une version simplifiée des équations générales ainsi obtenuesUnravelling the structure of the QCD phase diagram and its many aspects such as (de)confinementand chiral symmetry breaking, is one of the big challenges of modern theoretical physics, and manyapproaches have been devised to this aim. Since perturbation theory is believed to cease feasibilityat low energy scales, these approaches treat the relevant order parameters, the quark condensate andthe Polyakov loop, non-perturbatively. However, it is also well-established that the starting point forperturbation theory, the Fadeev-Popov gauge-fixing procedure, is inherently ill-defined in the infrareddue to the presence of Gribov ambiguities. In this context, a modified perturbative approach based onthe Curci-Ferrari Lagrangian has been introduced, where a phenomenologically motivated effective gluonmass term is added to the Landau gauge-fixed action. Prior to the beginning of the thesis, this approach hasproven extremely fruitful in its descriptions of (unquenched) Yang-Mills correlation functions and thermodynamics at (non)zero temperature and density.Throughout the thesis we extend this analysis to the entire phase structure of QCD and QCD-liketheories and test the validity of the model in various regimes of interest. For instance, to further aprevious one-loop study in the regime of heavy quark masses, we have computed the two-loop quarksunset diagram in the presence of a non-trivial gluon background in a finite temperature and densitysetting. We come to the conclusion that the physics underlying center symmetry is well-described by our perturbative model with a seemingly robust weak-coupling expansion scheme. Furthermore, we study the regime of light quarks by means of a recently proposed resummation scheme which exploits the presence of actual small parameters in the Curci-Ferrari description of infrared QCD. In the quark sector, this leads to the renown rainbow equations. We extend this first-principle setup to nonzero temperature, chemical potential, and gluon background. We perform a first qualitative analysis of the prediction of the model concerning the possible existence of a critical endpoint in the QCD phase diagram by using a simplified version of these general equations
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Pandiyan, Manoj Soundhira. "Phase diagram and control of thermoelectric properties of sodium cobaltate." Thesis, University of London, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.603508.
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The temperature-composition phase diagram of sodium cobaltate, NaxCo02, was determined over the range 0.32 < x < 0.85 and 90 < T < 500K. Sodium de-intercalation was achieved using Brz/CI-hCN as an oxidising agent, and the superstructures were determined using X-ray diffraction. A kaleidoscope of Na+ ion patterns were found, including both commensurate and incommensurate structures. The sodium ion patterning of some of the superstructures was solved via a model independent approach using Reverse Monte Carlo. Diffuse scattering was observed above the sodium ordering temperature. For high x, it was possible to reproduce the data using Monte Carlo simulations of short-range ordered 8lTangements of multi-vacancy clusters. For x :::: 0.5, the ordering consists of small regions of the superstructure confined to a single sodium plane. Old samples of sodium cobaltate are found to have de-intercalated so that the surface layer has a superstructure corresponding to a lower value of x than the bulk. The thermoelectric and magnetic properties change dramatically when the superstructures change from di-vacancies to tri-vacancies. In the case of x = 0.5 we are able to understand the resonant X-ray scattering from the electronic ordering directly from the superstructure.
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Gagliardi, Giuseppe [Verfasser]. "The QCD Phase Diagram from Strong Coupling Expansion / Giuseppe Gagliardi." Bielefeld : Universitätsbibliothek Bielefeld, 2020. http://d-nb.info/1211474089/34.
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Anzellini, Simone. "Phase diagram of iron under extreme conditions measured with time resolved methods." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066155/document.
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Cette thèse concerne l'étude du diagramme de phase du fer en conditions extrêmes de pression et température. La Terre possède un noyau interne solide et un noyau externe liquide, qui sont principalement composés de fer. Une détermination fiable de la température de fusion du fer à 330 GPa, pression au-delà de laquelle le noyau terrestre est solide, permet de contraindre la température du noyau, ce qui est essentiel pour comprendre la dynamique terrestre. Le diagramme de phase du fer a été étudié jusqu'à 200 GPa en cellule à enclumes de diamant chauffée par laser utilisant la diffraction par rayon X comme diagnostic de l¿apparition de la fusion. Les températures obtenues sont en accord avec celles mesurées par compression dynamique, aux incertitudes expérimentales près, et sont plus élevées que celles obtenues lors de précédentes expériences statiques utilisant un critère de fusion différent. L'appareil, les méthodes et la métrologie utilisés pour les expériences en cellule à enclume de diamant chauffée par laser sont présentées ainsi que les problèmes rencontrés dans les expériences statiques à de telles conditions extrêmes. La possibilité d'utiliser le signal de diffraction des rayons X du joint en Re à des fins d'étalonnage de la pression pour l'expérimentation dans le domaine du multi-Mbar est aussi abordée. Dans ce but, l'équation d¿état du Re a été mesurée à 144 GPa. En fin, un test préliminaire a été effectué pour vérifier la possibilité d'utiliser la spectroscopie d'absorption des rayons X en dispersion d'énergie comme une technique complémentaire à la diffraction des rayons X pour la détermination de la courbe de fusion du ferThis thesis concerns the study of the phase diagram of iron at extreme conditions of pressure and temperature. Iron is the main constituent of the terrestrial planetary cores. In particular, the Earth has a solid inner core and a liquid outer core which are mainly composed of iron. The accurate determination of the melting temperature of iron at the inner core boundary pressure, 330 GPa, would provide an important constraint on the temperature of the core, which is essential to understand how the dynamic Earth works. The phase diagram of iron has been investigated in laser-heated diamond anvil cell experiments up to 200 GPa using synchrotron-based fast X-ray Diffraction as a primary melting diagnostic. The obtained melting temperatures agree within the experimental uncertainties with the ones obtained from shock wave experiments and are higher than those reported by previous static experiments, where a different melting criterion was used. The apparatus, methods and metrology used in the static laser heated diamond anvil cell are discussed together with the issues encountered in static experiments at such extreme conditions. The possibility of using the X-ray diffraction signal of Re gasket for pressure calibration purpose for experiment in the multi-Mbar range is also discussed. For this purpose, Re equation of state has been measured up to 144 GPa. Finally, a preliminary test has been performed to check the possibility of using energy dispersive X-ray absorption spectroscopy as a technique complementary to fast X-ray diffraction in the investigation of the melting curve of iron
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Skellern, Matthew G. "Structural and electronic properties of barium lanthanum vanadates." Thesis, University of Aberdeen, 2003. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU167989.
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A study of the subsolidus region of the BaO-La2O3-V 2O5 phase diagram has been carried out. Four ternary phases can be prepared, one of which has not been previously identified. The four ternary phases are a palmierite solid solution Ba3-3xLa2x V2O8, Ba2LaV3O11, BaLa10V4O26 (new phase) and Ba3La 40V12O93. Addition of BaLa10V 4O26 and the previously omitted phase La1.42V 0.58)3.58 to the ternary system has resulted n a re-determination of the complete phase diagram. A comprehensive study of the Ba3-3xLa 2xV2O8 solid solution has been carried out, employing a number of techniques including x-ray diffraction, infra-red spectroscopy, thermogravemetric analysis, impedance spectroscopy, electron paramagenetic resonance spectroscopy, inductively coupled plasma mass spectroscopy and x-ray absorption near edge structure spectroscopy. Conductivity measurements show the end-member Ba3V2O8 to be an oxide ion conductor, with the conduction mechanism being facilitated by the ease of transformation of the BaO3 layers to BaO2 and vice versa. The La-doped members show an increase in conductivity, with electrons becoming the dominant conducting species. The crystal structure of Ba2LaV 3O11 was confirmed to be isostructural with Ba2BiV 3O11. A full refinement of the structural parameters has been performed. The unit cell is primitive monoclinic, a = 12.44510(3)A, b = 7.78854(12)A, c = 11.26245(21)A and beta = 103.134(4)°, space group P21/c. Preliminary structural studies have begun on the new phase BaLa10V4O26. The x-ray powder pattern has been fully indexed and a possible monoclinic unit cell of a = 20.2939A, b = 5.886A, c = 12.6234A and beta = 118.05° is proposed. The serendipitous synthesis of a barium-deficient celsian phase, Ba0.8A11.6 Si2.4O8, is reported; the structure was solved using Patterson methods. The phase has a monoclinic unit cell with, a = 8.6090(8)A, b = 13.0858(12)A, c = 7.2047(7)A and beta = 115.418(2)°, space group C2/m.
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Bourov, Geuorgui Kostadinov. "SIMULATION STUDIES OF SELF-ASSEMBLY AND PHASE DIAGRAM OF AMPHIPHILIC MOLECULES." Doctoral diss., University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3486.
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The aim of this dissertation is to investigate self-assembled structures and the phase diagram of amphiphilic molecules of diverse geometric shapes using a number of different computer simulation methods. The semi-realistic coarse-grained model, used extensively for simulation of polymers and surfactant molecules, is adopted in an off-lattice approach to study how the geometric structure of amphiphiles affects the aggregation properties. The results of simulations show that the model system behavior is consistent with theoretical predictions, experiments and lattice simulation models. We demonstrate that by modifying the geometry of the molecules, self-assembled aggregates are altered in a way close to theoretical predictions. In several two and three dimensional off-lattice Brownian Dynamics simulations, the influence of the shape of the amphiphilic molecules on the size and form of the aggregates is studied systematically. Model phospholipid molecules, with two hydrophobic chains connected to one hydrophilic head group, are simulated and the formation of stable bilayers is observed. In addition, (practically very important) mixtures of amphiphiles with diverse structures are studied under different mixing ratios and molecular structures. We find that in several systems, with Poisson distributed chain lengths, the effect on the aggregation distribution is negligible compared to that of the pure amphiphilic system with the mean length of the Poisson distribution. The phase diagrams of different amphiphilic molecular structures are investigated in separate simulations by employing the Gibbs Ensemble Monte Carlo method with an implemented configurational-bias technique. The computer simulations of the above mentioned amphiphilic systems are done in an area where physics, biology and chemistry are closely connected and advances in applications require the use of new theoretical, experimental and simulation methods for a better understanding of their self-assembling properties. Obtained simulation results demonstrate the connection between the structure of amphiphilic molecules and the properties of their thermodynamically stable aggregates and thus build a foundation for many applications of the remarkable phenomena of amphiphilic self-assembly in the area of nanotechnology.Ph.D.
Department of Physics
Arts and Sciences
Physics
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Huang, Gang. "Synthesis and study of crystalline hydrogels, guided by a phase diagram." Thesis, University of North Texas, 2004. https://digital.library.unt.edu/ark:/67531/metadc4698/.
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Monodispersed nanoparticles of poly-N-isopropylacrylamide-co-allylamine (PNIPAM-co-allylamine) and PNIPAM-co-acrylic acid (AA) have been synthesized and used as building blocks for creating three-dimensional networks. The close-packed PNIPAM-co-allylamine and PNIPAM-co-AA nanoparticles were stabilized by covalently bonding neighboring particles at room temperature and at neutral pH; factors which make these networks amicable for drug loading and release. Controlled release studies have been performed on the networks using dextran markers of various molecular weights as model macromolecular drugs. Drug release was quantified under various physical conditions including a range of temperature and molecular weight. These nanoparticle networks have several advantages over the conventional bulk gels for controlling the release of biomolecules with large molecular weights. Monodispersed nanoparticles of poly-N-isopropylacrylamide-co-allylamine (PNIPAM-co-allylamine) can self-assemble into crystals with a lattice spacing on the order of the wavelength of visible light. By initiating the crystallization process near the colloidal crystal melting temperature, while subsequently bonding the PNIPAM-co-allylamine particles below the glass transition temperature, a nanostructured hydrogel has been created. The crystalline hydrogels exhibit iridescent patterns that are tunable by the change of temperature, pH value or even protein concentration. This kind of soft and wet hydrogel with periodic structures may lead to new sensors, devices, and displays operating in aqueous solutions, where most biological and biomedical systems reside. The volume-transition equilibrium and the interaction potential between neutral PINPAM particles dispersed in pure water were investigated by using static and dynamic light-scattering experiments. From the temperature-dependent size and energy parameters, the Sutherland-like potential provides a reasonable representation of the inter-particle potential for PNIPAM particles in swollen and in collapsed phases. An aqueous dispersion of PNIPAM particles can freeze at both high and low temperatures. At low temperatures, the freezing occurs at a large particle volume fraction, similar to that in a hard-sphere system; while at high temperature, the freezing occurs at low particle concentrations, driven by the strong van der Waals attraction due to the collapsed microgel particles. The calculated phase diagram has been confirmed semi-quantitatively by experiments.
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Patel, Keyurkumar S. "Automatic generation of global phase equilibrium diagram from equation of state." [Tampa, Fla] : University of South Florida, 2007. http://purl.fcla.edu/usf/dc/et/SFE0002327.
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Lutsyk, V. I., and V. P. Vorobeva. "Reasons for Contradiction of T-X-Y Diagram Au-Bi-Sb in “Atlas of Phase Diagrams for Lead-Free Soldering”." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35472.
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The paper describes how 3D computer models of phase diagrams may be used for searching and correction
of mistakes in projections and sections of phase diagrams, designed by known thermodynamic methods.
The system Au-Bi-Sb from the Atlas of Phase Diagrams for Lead-Free Soldering is an example to
demonstrate searching of mistakes and reconstruction of missing surfaces and phase regions with a help of
3D computer model of its T-x-y diagram.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35472
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Sterpetti, Edoardo. "Phase diagram and fluctuations in two dimensional space charge doped Bi2Sr2CaCu2O8+x." Electronic Thesis or Diss., Sorbonne université, 2018. http://www.theses.fr/2018SORUS100.
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Le diagramme de phase des supraconducteurs à haute température critique en fonction du dopage et de la température a été étudié de manière intensive avec une variation chimique du dopage. Le dopage chimique peut provoquer des changements structurels et du désordre, masquant les effets intrinsèques. Alternativement, des échantillons ultra-minces dopés électrostatiquement peuvent être utilisés à travers des dispositifs de type transistors à effet de champ (FET). Cependant, nombreux défis technologiques sont à affronter lorsque des supraconducteurs à haute température sont concernés. Dans cette thèse nous surmontons ces obstacles en utilisant des techniques développées dans notre laboratoire et nous nous concentrons sur le supraconducteur à haute température BSCCO-2212 dont le diagramme de phase n'a jamais été étudié par effet électrostatique. Notamment, nous fabriquons des dispositifs supraconducteurs de BSCCO-2212 de haute qualité et utilisons une méthode électrostatique originale appelée dopage de charge d'espace, et mesurons les caractéristiques de transport de 330~K à basse température. Nous extrayons les paramètres et les températures caractéristiques sur une grande plage de dopage et établissons un diagramme de phase complet pour les échantillons BSCCO-2212 d'épaisseur 1~u.c. en fonction du dopage, de la température et du désordre. Nous identifions aussi la plage critique de dopage où une transition de phase quantique est prédite. Enfin, nous examinons de près la transition supraconductrice dans la limite de la bi-dimensionnalité. Les dispositifs BSCCO-2212 à 1 maille cristalline d'épaisseur. Les fluctuations et les effets extrinsèques sont décrits par des formalismes théoriques appropriés et le caractère bidimensionnel de la transition supraconductrice de BSCCO-2212 est analyséThe phase diagram of hole-doped high critical temperature superconductors as a function of doping and temperature has been intensively studied with chemical variation of doping. Chemical doping can provoke structural changes and disorder, masking intrinsic effects. Alternatively, electrostatically doped ultra-thin samples can be used through Field-Effect Transistor (FET) devices. The electrostatic modulation of charge carrier density in 2D materials is an elegant and clean approach that presents many technological challenges when high temperature superconductors are concerned. In this thesis we overcome these technological obstacles by using proprietary techniques developed in our laboratory for the study of 2D materials, and we focus on the high temperature superconductor BSCCO-2212, whose phase diagram has so far never been studied via electrostatic effect. Notably we fabricate ultra-thin high quality superconducting BSCCO-2212 devices and use an original electrostatic method called space charge doping to measure transport characteristics from 330~K to low temperature. We extract parameters and characteristic temperatures over a large doping range and establish a comprehensive phase diagram for one-unit-cell-thick BSCCO-2212 samples as a function of doping, temperature and disorder. We also identify the critical doping range where a quantum phase transition is predicted. Finally we take a closer look at the superconducting transition in the two dimensional limit. Fluctuations and extrinsic effects are accounted for using appropriate theoretical formalism and the two dimensional character of the superconducting transition of BSCCO-2212 is analysed
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Herrero, Bocco Bernardo. "Assessment of the ternary phase diagram on the stoichiometric and hypo-stoichiometric U-Nd-O system." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASC008.
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Cette thèse concerne l’étude expérimental et la modélisation thermodynamique du comportement des combustibles avancés utilisés dans les centrales nucléaires actuelles et de future génération. L’objet de la thèse est plus précisément l’étude du système ternaire (U-Nd-O) et pour comparaison du système ternaire (U-Ce-O). Ce système est particulièrement représentatif des produits de fissions accumulés dans le combustible pour des taux de combustion élevés mais aussi du dopage initial du combustible avec des poisons neutroniques utilisés dans des combustibles à fort taux d’enrichissement en mesure d’espacer les arrêts réacteur. L’étude de ce système présente des défis importants en raison du conflit ouvert entre phénomènes thermodynamiques et cinétiques. Il s’agit en effet d’un système hors équilibre où la mise en ordre à longue porté des structures locales est frustrée par la faiblesse du transport cationique dans la plage de températures d’intérêt pour les applications. Au cours de cette thèse, une révision de la littérature existante a motivé la fabrication d’échantillons aux caractéristiques bien définies par des méthodes de métallurgie des poudres et par des méthodes de chimie douce aboutissant à un contrôle des distributions des dopants. Les résultats obtenus par de nombreuses techniques de caractérisation (DRX, MEB, MET, XAS) sur des échantillons traités thermiquement dans des conditions oxydantes ou réductrices ont permis une réévaluation critique des diagrammes de phases actuellement utilisés. Nous avons pu proposer des modifications aboutissant à un nouveau diagramme de phases permettant une meilleure connaissance des limites d’utilisation des combustibles dans des conditions de sécurité optimalesThis thesis concerns the experimental study and thermodynamic modeling of the behavior of advanced fuels used in current and future generation nuclear power plants. The subject of the thesis is more precisely the study of the ternary system (U-Nd-O) and for comparison purposes of (U-Ce-O). This system is particularly representative of the fission products accumulated in the fuel for high combustion rates but also of the initial atomic substitutions in the fuel by neutron poisons, used in nuclear fuels with high enrichment levels and capable of spacing out nuclear reactor outages. The study of this system presents significant challenges due to the open conflict between thermodynamic and kinetic phenomena. It is indeed an out of equilibrium system where the long-range ordering of local structures is frustrated by the negligible of atomic transport in the cation sublattice in the range of temperatures of interest for applications. During this thesis, a review of the existing literature motivated the manufacture of samples with well-defined characteristics by powder metallurgy methods and by soft chemistry methods leading to a control of dopant distributions. The results obtained by numerous characterization techniques (XRD, SEM, TEM, XAS) on samples treated thermally under oxidizing or reducing conditions have allowed a critical re-evaluation of the phase diagrams currently used. We have modelled a new phase diagram that includes new experimental results. This allows a better knowledge of the limits of use of nuclear fuels respecting optimal safety conditions
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Ikoma, Daisaku, Hiroki Tsuchiura, and Jun-ichiro Inoue. "Magnetic phase diagram of metallic pyrochlore lattice in the double-exchange model." The American Physical Society, 2003. http://hdl.handle.net/2237/7114.
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Gräfe, Uwe. "Investigation of the Superconducting and Magnetic Phase Diagram of Off-Stoichiometric LiFeAs." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-233972.
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At their discovery in 2008, iron pnictide superconductors (IPS) provoked tremendous scientific interest, comparable to the discovery of the cuprate superconductors. So far, IPS reached critical temperatures T c up to 56K. Typically, they show an antiferromagnetic (afm) spin density wave (SDW) which has to be suppressed by doping before superconductivity develops, which then is supported by further doping. Due to the close vicinity of the magnetic and the superconducting (sc) phase, magnetic fluctuations are discussed to be responsible for the sc pairing mechanism in IPS.
A special member of the IPS is LiFeAs, because it does not need doping to become sc. It is a stoichiometric superconductor at a T c of 18K. In fact, doping is suppressing its T c . Also, there is no sign of an afm SDW present. Therefore, LiFeAs is a interesting material to study the properties of the IPS in an undisturbed material. In 2010, experiments of the Leibniz Institute for Solid State and Materials Research Dresden (IFW Dresden) revealed further surprising properties of LiFeAs. Samples with a Li deficiency undergo a ferromagnetic (fm) phase transition at 165K. Theoretical calculations suggest that fm fluctuations could induce triplet superconductivity in LiFeAs. This would cause a nonvanishing dynamic susceptibility below T c , which is supported by nuclear magnetic resonance (NMR) experiments.
This thesis is discussing the results of the IFW Dresden experiments, and concludes that this ferromagnetism is of weak itinerant nature. The origin might be an increase of the density of states (DOS) at the Fermi level, which is causing an instability towards fm order, as proposed by the Stoner model. For further doping experiments, the synthesis procedure of polycrystalline LiFeAs was optimized to get samples with maximum T c and minimum impurities. Therefore, nuclear quadrupole resonance (NQR) was used. The NQR line width is a measure of impurities in the sample. By minimizing the NQR line width, optimal samples were synthesized. These samples are able to compete with the properties of single crystals. To investigate the doping behavior of LiFeAs, a scenario with four different kinds of impurities and deficiencies was performed with the optimized synthesis procedure. 24 different samples were analyzed, by means of NQR and electrical conductivity. It was found that in fact Fe excess is responsible for changing the physical properties of LiFeAs, and not Li deficiency. It is causing a shrinking of the unit cell volume, as seen by X-ray diffraction (XRD) measurements and it causes a decrease of T c . It also leads to a decrease of room temperature resistivity, which is supporting an increase of the DOS at the Fermi level. The NQR frequency is scaling with the amount of Fe excess and can be used to draw the sc and fm phase diagram of off-stoichiometric LiFeAs. At an amount between 3.2 and 3.6% o f Fe excess LiFeAs undergoes the fm transition.
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Horrocks, P. J. "Phase diagram and thermodynamics of the Ag-Cd-In ternary alloy system." Thesis, University of Manchester, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.508170.
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Steinberg, Aman. "The Functional Renormalisation Group and the Phase Diagram of Strongly Interacting Matter." Thesis, Uppsala universitet, Kärnfysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-213291.
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Jacobs, Thorsten. "Unraveling the cuprate superconductor phase diagram : Intrinsic tunneling spectroscopy and electrical doping." Doctoral thesis, Stockholms universitet, Fysikum, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-129270.
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High-temperature superconductors belong to the group of strongly correlated materials. In these compounds, complex repulsive electron interactions and a large number of degrees of freedom lead to a rich variety of states of matter. Exotic phases like the pseudogap, charge-, spin- and pair-density waves, but also the remarkable phenomenon of superconductivity emerge, depending on doping level and temperature. However, up to now it is unclear what exactly causes these states, to what extent they are coexisting or competing, and where their borders in the phase diagram lie. A better understanding could help in finding the mechanism behind high-temperature superconductivity, but would also provide a better insight into the puzzling behavior of strongly correlated materials. This thesis tries to resolve some of these questions with focus on the underdoped pseudogap regime. Mesa structures of bismuth-based cuprate superconductors were studied using intrinsic tunneling, which allows spectroscopic characterizations of electronic density of states inside the material. A micro/nano fabrication method was developed to further reduce mesa areas into the sub square-micrometer range, in order to minimize the effect of crystal defects and measurement artifacts caused by heating induced by the measurement current. The comparison of energy scales in Bi-2201 and Bi-2212 cuprates shows that the pseudogap phenomenon is not connected to superconductivity, but possibly represents a competing spin-singlet order that is universal to all cuprates. The analysis of the upper critical field in Bi-2201 reveals a low anisotropy, which gives evidence of paramagnetically limited superconductivity. Furthermore, a new electrical doping method is demonstrated, which enables the reversible tuning the doping level of Bi-2212 and study a broad doping range upon a single sample. Using this method, two distinct critical points were observed under the superconducting dome in the phase diagram: one at the overdoped side, associated with the onset of the pseudogap and a metal to insulator transition, and one at optimal doping, associated with an enhanced "dressed" electron energy. Finally, a novel angular-dependent magnetotunneling technique is introduced, which allows for the separation of the superconducting and non-superconducting contributions to the pseudogap phenomenon. The method reveals that after an abrupt decay of the energy gap for T→Tc, weak superconducting correlations persist up to several tens of degrees above Tc.
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Zhang, Haiwa. "Experimental investigation of the phase diagram of ammonia monohydrate at high pressure and temperature." Electronic Thesis or Diss., Sorbonne université, 2019. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2019SORUS410.pdf.
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Cette thèse de physique expérimentale explore le diagramme de phase du monohydrate d'ammoniac (AMH) à haute pression (0This thesis in experimental physics investigates the phase diagram of ammonia monohydrate (AMH) at high pressure (0
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Ichihara, Terukazu. "Fluctuations in QCD phase diagram in the strong coupling limit of lattice QCD." 京都大学 (Kyoto University), 2016. http://hdl.handle.net/2433/215301.
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権利表示を行うこと, 出典表示を行うこと, 出版社版へのリンクを表示することKyoto University (京都大学)
0048
新制・課程博士
博士(理学)
甲第19488号
理博第4148号
新制||理||1596(附属図書館)
32524
京都大学大学院理学研究科物理学・宇宙物理学専攻
(主査)教授 大西 明, 准教授 菅沼 秀夫, 教授 田中 貴浩
学位規則第4条第1項該当
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Welzbacher, Christian Andreas [Verfasser]. "Quarks and gluons in the phase diagram of quantum chromodynamics / Christian Andreas Welzbacher." Gießen : Universitätsbibliothek, 2016. http://d-nb.info/1112909974/34.
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Haas, Lisa Marie [Verfasser], and Jan Martin [Akademischer Betreuer] Pawlowski. "On the phase diagram of QCD / Lisa Marie Haas ; Betreuer: Jan Martin Pawlowski." Heidelberg : Universitätsbibliothek Heidelberg, 2012. http://d-nb.info/117703963X/34.
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Yin, Yan. "The thermodynamics and phase diagram data for the system Zr02[subscript]-CaO-MgO." Thesis, University of Sheffield, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.579724.
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Michnick, Robin Beth. "Phase diagram determination and relative dielectric constant measurements of the butyronitrile-chloroethane system." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/32168.
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Lyman, Edward. "Phase Diagram of a Driven Lattice Gas of Two Species with Attractive Interactions." Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/27513.
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We study the phase diagram of an interacting lattice gas of two species of particles and holes, driven out of equilibrium by a local hopping bias (denoted by `E').
Particles interact by excluded volume and nearest-neighbor attractions. We present a detailed Monte Carlo investigation of the phase diagram. Three phases are found, with a homogenous phase at high temperatures and two distinct ordered phases at lower temperatures. Which ordered phase is observed depends on the parameter f, which controls the ratio of the two types of particles. At small f, there is nearly a single species, and a transition is observed into a KLS-type ordered phase. At larger f, the minority species are sufficiently dense to form a transverse blockage, and a sequence of two transitions are observed as the temperature is lowered.
First, a continuous boundary is crossed into an SHZ-type ordered phase, then at a lower temperature a first-order boundary is crossed into the KLS-type ordered phase. At some critical value of f is a bicritical point, where the first-order line branches from the two continuous boundaries. We also consider correlations in the homogenous phase, by constructing a continuum description and comparing to the results of simulations. Long range correlations are present in both the theoretical results and the simulations, though certain details of the theory do not fit the observations very well. Finally, we examine the beahvior of three-point correlations in the single-species (KLS) limit. Nontrivial three-point correlations are directly related to the nonzero bias E. We therefore consider the behavior of the three-point correlations as a function of E. We find that the three-point signal saturates very rapidly with E. There are some difficulties interpreting the data at small E.Ph. D.
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Parks, Michael Lawrence. "Efficient Numeric Computation of a Phase Diagram in Biased Diffusion of Two Species." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/32896.
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A lattice gas with equal numbers of oppositely charged particles, diffusing under the influence of a uniform electric field and an excluded volume condition undergoes an order-disorder phase transition, controlled by the particle density and the field strength. This transition may be continuous (second order) or continuous (first order). Results from previous discrete simulations are shown, and a theoretical continuum model is developed. As this is a nonequilibrium system, there is no associated free energy to determine the location of a first order transition. Instead, the model equations for this system are evolved in time numerically, and the locus of this transition is determined via the presence of a stable state with coexisting regions of order and disorder. The Crank-Nicholson, nonlinear Gauss-Seidel, and GMRES algorithms used to solve the model equations are discussed. Performance enhancements and limits on convergence are considered.Master of Science
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Cuk, Tanja. "Investigation of the high-Tc phase diagram using optical spectroscopies and high pressures /." May be available electronically:, 2007. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Sun, Chia-Chun, and 孫家駿. "ECG Analysis by Phase Diagram." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/92642355871288147489.
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Boniface, Tracy Diane. "The ruthenium-aluminium phase diagram." Thesis, 2016. http://hdl.handle.net/10539/20874.
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A dissertation submitted to the Faculty of Engineering, University of the Witwatersrand)
in partial fulfilment of the requirements for the degree of Master of Science in Engjneering
Johannesburg, 1994Recent international investigations into new advanced materials have shown that the intennetallic compound, RuA1, possesses prormising characteristics for high-temperature use in corrosive environments. In order to optimise production of this alloy, an understanding of the Ru-A1 system is necessary. [Abbreviated Abstract. Open document to view full version]
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Chen, Ta-Yuan, and 陳大元. "Phase Diagram of Dusty Plasma." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/57684432082505895383.
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Chen, Dai-Yuan, and 陳大元. "Phase Diagram of Dusty Plasma." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/62236262387051663526.
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Xiao, Xuhui, and 蕭旭暉. "Phase diagram of colloid-rod system." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/5834ac.
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碩士國立中央大學
物理研究所
97
The semi-grand ensemble theory [H.N.W. Lekkerkerker, Europhys. Lett. 20, 559 (1992)] in conjunction with the fundamental measure density functional theory [V.B. Warshavsky and Xueyu Song, Phys. Rev. E 69, 061113 (2004)] are used to construct the Helmholtz free energy density for both the solid and liquid phases. Given these free energy density functions, we apply the free energy density minimization method [G.F. Wang, S.K. Lai, Phys. Rev. E 70, 051402 (2004)] to crosshatch the coexistence regions of a mixture of uncharged colloidal hard spheres and colloidal rods. The calculated results show that the triangular area bounded by gas-liquid, gas-solid and liquid-solid coexisting phases which has been called coexistence region of gas-liquid-solid corresponds in fact to sets of two phases in coexistence. The phase boundaries which are delimitations of our calculated coexistence domains compare very well with previous theoretical calculations. The relevance of the phase-diagram domains to three phases in coexistence will be discussed.
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Liu, Chih-Hua, and 柳智華. "Zr-Cu-Ni Phase Diagram at 800℃." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/35921417714601195951.
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碩士國立中山大學
材料科學研究所
92
Zirconium base alloys have very good metallic glass forming ability. In this study,the Zr-Cu-Ni ternary isotherm at 800℃ were determined by using metallography,electron-probe microanalysis and X-ray diffraction.The main objective is to provide the necessary information for alloy design to form new Zr-base with better glass forming ability.
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Weng, Ying Che, and 翁穎哲. "The Phase Diagram Analysis for YBCO Material." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/60295305652900591890.
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Pereira, Renan Câmara. "Quantum Chromodynamics Phase Diagram Under Extreme Conditions." Doctoral thesis, 2021. http://hdl.handle.net/10316/95294.
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Tese no âmbito do Doutoramento em Física, ramo de Física Nuclear e das Partículas, apresentada ao Departamento de Física da Faculdade de Ciências e Tecnologia da Universidade de Coimbra.In this work, different aspects of the phase diagram of strongly interacting matter are explored using effective models of Quantum Chromodynamics (QCD) under various approximations. We use the Nambu-Jona-Lasinio (NJL) model, in its two and three flavour versions, including different types of quark interactions. We also consider the two flavour Quark-Meson (QM) model with vector interactions, which can be interpreted as a bosonized version of the NJL model. Considering the usual mean field approximation, an extended three flavour NJL model, which includes the Polyakov loop, with eight-quark scalar and pseudoscalar interactions is used to study the QCD phase diagram. We also analyse the properties of isentropic trajectories along the different regions of the diagram, including the crossing of the first-order phase transitions. We find that, within this model, it is possible to have two different critical endpoints with the respective first-order lines, related to the light and strange sectors of QCD. We apply the zero temperature three flavour NJL model, in beta-equilibrium to study the stability of neutron stars in accordance with the latest astrophysical constraints from NICER, LIGO/Virgo and the pulsars with approximately two solar masses, PSR J1614-2230 and PSR J0348+0432. The model includes four-quark and eight-quark vector-isoscalar interactions. We find quark matter in the core of moderately low mass neutron stars. The existence of quark matter inside these neutron stars imprints the tidal deformability when compared to the expected results for purely hadronic neutron stars. It follows that, low values of tidal deformability for low/intermediate mass stars, might be a possible observational signature for the existence of quark matter in the core of neutron stars. In a second part, we perform beyond mean field studies including the so-called one-meson-loop approximation to the NJL model and the Functional Renormalization Group (FRG) method applied to the QM model. In the case of the one-meson-loop NJL, quantum fluctuations are introduced in a symmetry conserving way, by including collective and non-collective modes in the gap equation of the model which originate from poles and branch cuts in the complex plane, respectively. The inclusion of these modes leads to a non-standard quark condensate as a function of temperature. However, it is possible to distinguish two regions, one with a large quark condensate and the other with a small quark condensate. These regions are separated by the melting temperature of the collective modes, the so-called Mott temperature. The application of the FRG to the two flavour QM model is known to lead to an unphysical region of negative entropy density, near the first-order phase transition of the model. We explore the connection between this unphysical region and the chiral critical region, especially the first-order and spinodal lines, using different vector interactions. We find scenarios where the phase diagram presents a first-order phase transition, without negative entropy, for a high enough vector interaction.
Neste trabalho exploram-se diferentes aspetos do diagrama de fases de matéria que interage fortemente, usando modelos efetivos da Cromodinâmica Quântica (QCD) sob várias aproximações. Para isso, recorre-se a modelos efetivos da QCD, nomeadamente ao modelo de Nambu-Jona-Lasinio (NJL), nas suas variantes de dois e três sabores, incluindo diferentes tipos de interações entre quarks, e também ao modelo Quark-Mesão (QM) com interações vetoriais, na versão de dois sabores, que pode ser interpretado como uma versão bosonizada do modelo de NJL. Numa primeira fase, considera-se a aproximação de campo médio para uma versão generalizada do modelo NJL, com três sabores, incluindo o loop de Polyakov e com interações de oito quarks escalares e pseudoescalares, para estudar o diagrama de fases da QCD. Também são analisadas as propriedades de trajetórias isentrópicas ao longo de diferentes regiões do diagrama de fases, incluindo as linhas que cruzam a região onde existe uma transição de fase de primeira ordem. Conclui-se que, neste modelo, é possível encontrar dois pontos críticos diferentes, assim como as respetivas linhas de transição primeira ordem, associados aos sectores leve e estranho da QCD. Numa aplicação à descrição de objetos compactos, usamos uma versão de três sabores do modelo NJL no limite de temperatura zero, em equilíbrio-beta para estudar a estabilidade de estrelas de neutrões que estão de acordo com as restrições astrofísicas impostas pelas observações de NICER, LIGO/Virgo e dos pulsares PSR J1614-2230 e PSR J0348+0432 com cerca de duas massas solares. O modelo também inclui interações vectoriais-isoscalares de quatro e oito quarks. Neste contexto, verificou-se que pode existir matéria de quarks no interior de estrelas de neutrões moderadamente leves. A existência de matéria de quarks no interior dessas estrelas de neutrões afeta a deformabilidade de maré, quando comparado ao resultado esperado de estrelas compostas apenas por matéria hadrónica. Conclui-se que valores baixos de deformabilidade de maré para estrelas com massas baixas/moderadas, pode ser usado como uma possível assinatura observacional da existência de matéria de quarks no núcleo de estrelas de neutrões. Numa segunda fase, realizaram-se estudos para além da aproximação de campo médio usando a aproximação de um-loop-mesónico no modelo de NJL e o Grupo de Renormalização Funcional (FRG) aplicado ao modelo de QM. No estudo envolvendo o modelo NJL com um-loop-mesónico, as flutuações quânticas são introduzidas de modo a não quebrar as simetrias do modelo, incluindo os modos coletivos e não coletivos na equação do gap com origem, respetivamente, nos polos e linhas de corte no plano complexo. A introdução destes modos leva a um comportamento não convencional do condensado de quarks em função da temperatura. Contudo, ainda é possível distinguir duas regiões, uma em que o condensado de quarks tem um valor elevado e outra onde ele é muito suprimido. Estas regiões são separadas pela temperatura em que os modos coletivos ``derretem'', a chamada temperatura de Mott. É sabido que a aplicação do FRG ao modelo QM de dois sabores leva ao aparecimento de uma região não-física de densidade de entropia negativa na vizinhança da linha de transição de primeira ordem do modelo. Ao investigar a ligação dessa região não-física e a região quiral crítica na presença de interações vetoriais diferentes, com ênfase na linha de primeira ordem e respetivas linhas spinodais, encontraram-se cenários, para interações vetoriais suficientemente intensas, em que o diagrama de fases apresenta uma transição de primeira ordem sem entropia negativa.
Projecto UID/FIS/04564/2019 - Fundação para a Ciência e a Tecnologia, I.P, Portugal
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Chang, Cheng-chun, and 張正群. "Ti-Co-Pd 800℃ phase diagram study." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/72057319517834869553.
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碩士國立中山大學
材料與光電科學學系研究所
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Titanium alloy has excellent mechanical properties, thermal properties and biocompatibility, it has been applied as aerospace materials and biomaterials. The adding of cobalt and palladium elements may improve the ductility and plasticity. The study of Ti-Co-Pd ternary phase diagram could provide the information of titanium alloy design. In this study, both the diffusion couple and the equilibrated alloys methods are applied to determine the Ti-Co-Pd 800℃isothermal phase diagram. The specimens were prepared by an electric arc furnace. then seal in a vacuum quartz tube, after high temperature heat treatment and metallurgical treatment, using electronic micro-finder (EPMA) to analysis the equilibrium phase composition. There are eleven three-phase equilibrium determined in this study. In comparison with the previous study, there are five different three-phase equilibrium as, TiCo2-Ti(Co,Pd)-TiPd2, Ti(Co,Pd)-TiCo2(h)-Ti2Co3Pd3, TiPd3-αTiPd2-Ti(Co,Pd) ,Ti2Co3Pd3-(Co,Pd)-TiCo3,βTi-Ti2Co-Ti2Pd observed in this study. The composition range of a ternary phase Ti2Co3Pd3: Ti: 23.09 at. % ~ 27.49at.%, Co: 27.55at.% ~ 47.87at.%, Pd: 26.08at.% ~ 42.96at.%, is also included.
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Scarola, Vito W. "Phase diagram of the fractional Quantum Hall." 2002. http://www.etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-173/index.html.
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