Tesis sobre el tema "Thermodynamic instabilities and phase transition"
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Burger, Florian. "The finite temperature QCD phase transition and the thermodynamic equation of state". Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2013. http://dx.doi.org/10.18452/16679.
Texto completoIn this thesis we report about an investigation of the finite temperature crossover/phase transition of quantum chromodynamics and the evaluation of the thermodynamic equation of state. To this end the lattice method and the Wilson twisted mass discretisation of the quark action are used. This formulation is known to have an automatic improvement of lattice artifacts and thus an improved continuum limit behaviour. This work presents first robust results using this action for the non-vanishing temperature case. We investigate the chiral limit of the two flavour phase transition with several small values of the pion mass in order to address the open question of the order of the transition in the limit of vanishing quark mass. For the currently simulated pion masses in the range of 300 to 700 MeV we present evidence that the finite temperature transition is a crossover transition rather than a genuine phase transition. The chiral limit is investigated by comparing the scaling of the observed crossover temperature with the mass including several possible scenarios. Complementary to this approach the chiral condensate as the order parameter for the spontaneous breaking of chiral symmetry is analysed in comparison with the O(4) universal scaling function which characterises a second order transition. With respect to thermodynamics the equation of state is obtained from the trace anomaly employing the temperature integral method which provides the pressure and energy density in the crossover region. The continuum limit of the trace anomaly is studied by considering several values of Nt and the tree-level correction technique.
Teng, Lidong. "Thermodynamic investigations of transition metal systems containing coabon and nitrogen". Doctoral thesis, KTH, Materials Science and Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-24.
Texto completoIn view of the important applications of carbides and carbo-nitrides of transition metals in the heat-resistant and hard materials industries, the thermodynamic activities of Cr and Mn in the Cr-C, Fe-Cr-C, Mn-Ni-C and Mn-Ni-C-N systems have been studied in the present work by the use of the galvanic cell technique. CaF2 single crystals were used as the solid electrolyte. The phase relationships in selected regions of the systems in question were investigated by the use of the equilibration technique. The phase compositions and microstructures of the alloys were analysed by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM).
In the Cr-C system, the Gibbs energy of formation of Cr3C2 were obtained from ElectroMotive Force (EMF) measurements conducted in the temperature range 950-1150 K. The values of the enthalpy of formation of Cr3C2 were evaluated by the third-law method. The ground-state energy of the hypothetic end-member compound CrC3, in the bcc structure at 0 K, was calculated by use of the Ab-initio method. Based on the obtained results the Cr-C system was reassessed by use of the CALPHAD approach.
In the Fe-Cr-C system, 16 different alloys were quenched at 1223 K and their equilibrium phases identified by XRD. The experimental results show that the substitution of Cr by Fe in the (Cr,Fe)7C3 carbide changes the lattice parameters of the phase. A slight decrease of the lattice parameters with an increase in the Fe content was established. The lattice parameters of the γ-phase in the Fe-Cr solid solution did also show a decrease with an increase of the Fe content. The activities of chromium in Fe-Cr-C alloys were investigated in the temperature range 940-1155 K. The activity of chromium decreases with an increase in the Fe content when the ratio of C/(Cr+C) was constant. It was also established that the activity of chromium decreases with an increase of the carbon content when the iron content was constant. The experimental results obtained were compared with the data calculated by use of the Thermo-Calc software.
In the Mn-Ni-C system the phase relationships were investigated at 1073 K as well as at 1223 K. The experimental results obtained showed that the site fraction of Ni in the metallic sublattice of the carbides M23C6, M7C3 and M5C2 (M=Mn and Ni) was quite low (approximately 2~3 percent). The activities of manganese in Mn-Ni-C alloys were investigated in the temperature range 940-1165 K. The three-phase region γ/M7C3/graphite was partly constructed at 1073 K.
In the Mn-Ni-C-N system, nitrogen was introduced into Mn-Ni-C alloys by equilibrating with N2 gas. It was established that the solubility of nitrogen in the investigated alloys was effected by the carbon content, and that a (Mn,Ni)4(N,C) compound was formed in the nitrided alloys. EMF measurements were performed on Mn-Ni-C-N alloys in the temperature interval 940-1127 K. The addition of nitrogen to Mn-Ni-C alloys was found to decrease the activity of manganese. The negative effect of nitrogen on the activity of manganese was found to decrease as the carbon content increased.
Keywords: Thermodynamic activity; Galvanic cell technique; Transition metal carbides; Transition metal nitrides; Phase equilibrium; Thermodynamics; Differential thermal analysis; Scanning electron microscopy; Transmission electron microscopy; Ab-initio calculations; CALPHAD approach;
Chen, Xiaoye. "Transport and thermodynamic studies of the superconductors A3T4Sn13 and YFe2Ge2". Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/270025.
Texto completoSen, Sema. "Calculation Of Phase Diagrams And The Thermodynamic Quantities From The Mean Field Models Close To Phase Transitions In Molecular And Liquid Crystals". Phd thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/2/12610436/index.pdf.
Texto completoZhao, Ding. "Spherulitic Growth and Thermodynamic Equilibrium in Multicomponent Elastic Films Under Solvent-vapor Annealing". UKnowledge, 2018. https://uknowledge.uky.edu/math_etds/56.
Texto completoMa, Hong-Hao. "Thermodynamic properties of QCD matter and multiplicity fluctuations /". Guaratinguetá, 2019. http://hdl.handle.net/11449/190985.
Texto completoResumo: Uma característica vital da cromodinâmica quântica (QCD) está relacionada à simetria quiral. Isso é particularmente intrigante devido ao papel crítico da simetria quiral não abeliana dos spinores de Lorentz na física teórica moderna. Muitos esforços teóricos foram dedicados à sua quebra espontânea no vácuo, bem como a restauração da mesma no ambiente extremamente quente ou denso. Além disso, quarks e glúons tornam-se os graus de liberdade relevantes por meio da transição de desconfinamento do estado dos hádrons. O significado desta última está intimamente ligado às implicações da equação de Callan-Symanzik e à teoria do grupo renormalizado. No entanto, em princípio, ambas as transições acima podem ser descritas pela QCD. Os estudos da QCD na rede demonstraram que a transição do sistema é um cruzamento suave com a densidade bariônica nula e a massa de quarks estranhos grandes. No potencial químico finito, por outro lado, uma variedade de modelos prevê a ocorrência de uma transição de fase de primeira ordem entre a fase hadrônica e o plasma de quarks e glúons (QGP). Esses resultados indicam que um ponto crítico (CEP) pode estar localizado em algum lugar no diagrama de fases da QCD no qual a linha de transições de fase de primeira ordem termina. Espera-se que a transição seja de segunda ordem neste caso. De fato, entre outros objetivos estabelecidos, o programa Beam Energy Scan (BES) em andamento no Relativistic Heavy Ion Collider (RHIC) é impulsionado pela busca do CEP. Nesta t... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: One vital characteristic of the quantum chromodynamics (QCD) is regarding the chiral symmetry. This is particularly intriguing owing to the critical role of non-abelian gauge symmetry of Lorentz spinors in modern theoretical physics. Many theoretical efforts have been devoted concerning its spontaneously breaking in the vacuum, as well as the restoration at the extremely hot or dense environment. Furthermore, quarks and gluons become the relevant degrees of freedom through the deconfinement transition from the hadron state of matter. The significance of the latter is closely connected to the implications of the Callan-Symanzik equation and the theory of the renormalized group. Nonetheless, in principle, both of the above transitions can be described by the QCD. Lattice QCD studies demonstrated that the transition of the system is a smooth crossover at vanishing baryon density and large strange quark mass. At finite chemical potential, on the other hand, a variety of models predict the occurrence of a first-order transition between the hadronic phase and quark-gluon plasma (QGP). These results indicate that a critical endpoint (CEP) might be located somewhere on the QCD phase diagram at which the line of first-order phase transitions terminates. The transition is expected to be of second-order at this point. As a matter of fact, among other established goals, the ongoing Beam Energy Scan (BES) program at the Relativistic Heavy Ion Collider (RHIC) is driven by the search for th... (Complete abstract click electronic access below)
Doutor
Nowotny, Thomas. "Phase transitions and multifractal properties of random field Ising models". Doctoral thesis, Universitätsbibliothek Leipzig, 2004. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-37023.
Texto completoIn this work random field Ising models with quenched dichotomous symmetric random field are considered for the one-dimensional case and on the Bethe lattice. To this end the canonical partition function is reformulated to the partition function of one spin in an effective field. In the first part of the work the multifractal spectrum of this effective field is investigated, transitions in the spectrum are explained and inequalities between local and global generalized fractal dimensions are proven which allow to characterize the multifractal spectrum bei various bounds. A further part of the work is dedicated to the characterization of the measure of the local magnetization which is obtained by convolution of the measure of the effective field with itself. In this context the convolution of multifractals is investigated in a more general setup and relations between the multifractal properties of the convolution and the multifractal properties of the convoluted measures are proven. The phase transition from ferro- to paramagnetismus for the model on the Bethe lattice is investigated in the third part of the thesis. Apart from improved exact bounds for the uniqueness of the paramagnetic state essentially three criteria for the transition are developped and numerically evaluated to determine the transition line. The multifractal properties of the effective field for the model on the Bethe lattice finally turn out to be trivial because the interesting dimensions do not exist
Jones, Nicholaos John. "Ineliminable idealizations, phase transitions, and irreversibility". Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1163026373.
Texto completoSotiropoulou, Georgia. "The Arctic Atmosphere : Interactions between clouds, boundary-layer turbulence and large-scale circulation". Doctoral thesis, Stockholms universitet, Meteorologiska institutionen (MISU), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-134525.
Texto completoAt the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Manuscript.
Hiratsuka, Tatsumasa. "Kinetic Nature of Capillary Condensation in Nanopores". 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225638.
Texto completoLiu, Xiaomeng. "Study on composition dependent phase stability of Ni50MnxIn50-x shape memory alloys by ab-initio simulation". Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0050.
Texto completoA series of first-principle calculations to discover the martensitic transition of the Ni-Mn-In alloys were implemented using the pseudopotential method by VASP and the full charge density method by EMTO-CPA within the framework of the Density Functional Theory (DFT). In the stoichiometric Ni50Mn25In25 alloy, the effect of effective Coulomb and exchange parameters (U + J) on the phase stability, structural and magnetic properties was studied. The lattice parameters and the phase stability vary with the U and J couplings in the cubic L21 austenite. However, the bandgap is still showing metallic bonding in the cubic Ni50Mn25In25 alloy. To figure out the effect of excess Mn atoms on the preference of the martensite structure, the tetragonal distortion was employed in the off-stoichiometric Ni50MnxIn50-x alloys with different Mn contents. The calculations were conducted with the optimization of the magnetic structure, where the stoichiometric Ni50Mn25In25 alloy was served as the reference. The ground state-energy-resolved tetragonal distortion reveals that the excess Mn changes the preferred stable structure from the perfect cubic L21 structure to the tetragonally distorted structures. Furthermore, to find out more accurate preference of the martensite structure, the formation energies were calculated. The results show that, the orthorhombic structure is preferred at lower Mn concentrations (between 29 at. % and 40 at. %), whereas the tetragonal L10 structure is more stable at the higher Mn concentrations (above 40 at. %). Moreover, the effect of the Mn concentration on the magnetic properties was also studied. With the increase of the excess Mn content, the magnetic moment increases linearly in the ferromagnetic cubic L21 structure, whereas it varies in the two kinds of martensite. The excess Mn could lead to the coexistence of ferromagnetism and antiferromagnetism. The appearance of the antiferromagnetism could be attributed to the Ni-Mn antiferromagnetic interaction in the tetragonal martensite. Furthermore, the effects of Mn concentration and thermally excited contributions (including the vibrational, electronic excitation and magnetic contributions) on the phase stability of austenite and martensite from 0 K to finite temperatures in Heusler type Ni50MnxIn50-x shape memory alloys were also studied. Results show that at 0 K, the energy differences between the non-modulated (NM) martensite and the austenite become negative when extra Mn is added, indicating that the added Mn stabilizes the martensite and promotes martensitic transformation. At finite temperatures, the three thermal contributions (the vibrational, electronic excitation and magnetic contributions) were further calculated based on the equilibrium structure at 0 K. It was revealed that the vibrational entropies of the two phases increase with the increase of the temperature for all Mn contents. Under the two effects (temperature and Mn-content), the austenite has a larger vibrational entropy than the martensite, which indicates that the vibrational entropy contributes to promoting the martensitic transition. The Mn content and the temperature show a similar influence on the electronic entropies of the two phases. And the magnetic moments increase linearly with the Mn content, however, the influence of temperature is relatively small. Above 100 K, the magnetic moment of the austenite is higher than that of the martensite in ferromagnetic Ni50Mn29.25In20.75 alloy, suggesting that the magnetic entropy makes a similar contribution to promote the martensitic transformation, like the vibrational and electronic excitation entropies. The present work provides fundamental knowledge to understand the martensitic transition of off-stoichiometric Ni50MnxIn50-x alloys, which could be used for the design of ferromagnetic shape memory alloys with improved functional performances
Burger, Florian [Verfasser], Michael [Akademischer Betreuer] Müller-Preußker, Maria-Paola [Akademischer Betreuer] Lombardo y Edwin [Akademischer Betreuer] Laermann. "The finite temperature QCD phase transition and the thermodynamic equation of state : an investigation employing lattice QCD with N f = 2 twisted mass quarks / Florian Burger. Gutachter: Michael Müller-Preußker ; Maria-Paola Lombardo ; Edwin Laermann". Berlin : Humboldt Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2013. http://d-nb.info/1031956018/34.
Texto completoPagliari, L. "PARTICLE SIZE EFFECT ON KINETICS AND THERMODYNAMICS OF PHASE TRANSITIONS IN MINERALS". Doctoral thesis, Università degli Studi di Milano, 2015. http://hdl.handle.net/2434/260489.
Texto completoMoles, Jordan. "On concentration inequalities for equilibrium states in lattice and symbolic dynamical systems". Thesis, Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAX102.
Texto completoThis thesis deals with the existence of Gaussian concentration for sufficiently mixing equilibrium states for lattice systems. Moreover, we show that such a property ensures uniqueness.In the first chapter, we show that if an equilibrium state associated to a shift-invariant and absolutely summable potential satisfies a Gaussian concentration bound then it is à fortiori mixing and unique em i.e. there is no phase transition.Thereafter, We study numerically a particular physical model which allows phase transition to occur: the ferromagnetic Ising model in two dimensions. We evaluate concentration constants through classical estimates at all temperature. Thank to the behavior of these parameters, we emphasize divergence of the Gaussian concentration constant at the critical temperature deduce that such property doesn't hold.Later on, we prove that the Gaussian concentration behavior holds for all temperature above the critical one for this model.Then, we dedicate a chapter to the study of an unidimensional symbolic dynamics on a finite alphabet: chains with complete connections. In particular, we study the concentration properties of a unique equilibrium state associated to a potential (or transition probability) satisfying Walters' condition.In the end, we review the high-noise regime in probabilistic cellular automata. In particular, we prove that in this regime, the probabilistic cellular automata satisfies a Gaussian concentration for a certain class of spatio-temporal observables
Ghesmoune, Mohammed. "Avancement de la méthode de saturations négatives pour les écoulements multi-composants multi-phasiques avec gravité et diffusion". Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0031/document.
Texto completoIn this thesis, two problems related to compositional multiphase flow in porous media have been treated. The first part is devoted to develop a new approach which gives a form of equilibrium equations which can be solved analytically even for multi-component non ideal systems and even in the presence of capillary effects, which reduce significantly computational time. In this approach, separate behaviors of gas, liquid and two phase fluid may be described using very simple equations of state (EOS). Capacity of EOS?s to capture two phase state is called: consistency conditions. These conditions are formulated in this part for multi-components systems. The second part is devoted to develop the negative saturations method which was proposed earlier by our group for the case of two-phase binary mixtures. First, we have developed the mathematical theory of the method for ideal mixtures in 1D case. Next, we have generalized the method for the case of any number of phases and chemical components. We have obtained the new equivalent uniform multi-phase equations which contain additional non-classical terms responsible of diffusion and gravity across the interfaces of phase transition
Tastevin, Geneviève. "Helium trois polarise : ondes de spin et liquefaction du gaz". Paris 6, 1987. http://www.theses.fr/1987PA066114.
Texto completoDerenne, Sylvie. "Contribution a l'etude des proprietes physiques de mineraux du manteau inferieur". Paris 6, 1988. http://www.theses.fr/1988PA066281.
Texto completoGachon, Jean-Claude. "Enthalpies de formation des composés binaires de métaux de transition par réaction directe dans un calorimètre 1800 K. : Discussion de méthodes de prévisions thermodynamiques et structurales". Nancy 1, 1986. http://www.theses.fr/1986NAN10055.
Texto completoBelgacem, Bouzida Aïssa. "Méthodes calorimétriques appliquées aux systèmes métalliques : 1) Thermodynamique du système (MO, GA) et première approche du système (NB, GA) : 2) Mesure automatique des capacités thermiques". Nancy 1, 1989. http://www.theses.fr/1989NAN10464.
Texto completoЗаскока, Антон Миколайович, Антон Николаевич Заскока y Anton Mykolaiovych Zaskoka. "Фазові переходи в ультратонких твердоподібних плівках мастила при межовому терті". Thesis, Вид-во СумДУ, 2015. http://essuir.sumdu.edu.ua/handle/123456789/43321.
Texto completoДиссертация посвящена исследованию процессов граничного трения в рамках термодинамической модели плавления ультратонкой пленки смазки, зажатой между двумя атомарно-гладкими твердыми поверхностями. Плавление и затвердевание смазки описываются как фазовые переходы первого и второго рода. Описано поведение двух механических аналогов трибологических систем – при сдвиге верхней поверхности в одну сторону и при внешнем знакопеременном воздействии. Показано, что в зависимости от параметров системы возможна реализация режимов сухого, прерывистого и жидкостного трения. Выяснено, что увеличение температуры смазки и/или скорости сдвига приводит к уменьшению максимальных значений силы трения. Изучено влияние коэффициента пропорциональности между вязкостью и скоростью сдвига, коэффициента жесткости пружины, циклической частоты, различных типов смазок (псевдопластических, дилатантных и ньютоновских) на поведение трибологических систем. Анализ термодинамического потенциала позволил выделить критические значения температур плавления и затвердевания смазки, которые совпадают при реализации в системе фазового перехода второго рода, и различны при протекании фазового перехода первого рода. Установлено, что ширина гистерезиса по температуре значительно увеличивается при наличии пружины между блоком и внешним приводом. Гистерезис по скорости сдвига в таком случае отсутствует. Проведен учет универсальной зависимости вязкости полимерных смазок от температуры и градиента скорости. Эта зависимость показывает, что логарифм эффективной вязкости пропорционален логарифму скорости сдвига. Коэффициент пропорциональности изменяет свое значение от 1 в твердоподобном состоянии до 0 в жидкоподобном (ньютоновская жидкость). При этом исследованы свойства смазки при низких температурах и скоростях сдвига. Построена трехмерная зависимость силы трения от температуры и скорости сдвига. С помощью учета зависимости вязкости от температуры и градиента скорости удалось описать квазистатическую компоненту силы трения. Построена зависимость силы трения от времени при продолжительной остановке внешнего привода. Смоделированы эффекты памяти граничной смазки, которые проявляются в том, что поведение системы в последующий момент времени зависит от предыдущего состояния. Изучено поведение при различных значениях внешней нагрузки. Построены зависимости для параметров смазок, состоящих из алканов различной длины, продемонстрированы и объяснены отличия для различных типов смазок. Проведена дальнейшая модификация термодинамического потенциала путем учета линейного слагаемого в разложении свободной энергии по степеням параметра порядка. Рассчитаны критические значения температуры и скоростей плавления и затвердевания смазки в этом случае для фазовых переходов первого и второго рода. Найдено соотношение между параметрами разложения при которых в системе реализуется фазовый переход первого либо второго рода. Показано, что расплавленному состоянию смазки может отвечать ненулевое значение параметра порядка. Такой вид потенциала дал возможность описать квазистатическую силу трения базируясь на новом подходе. На его основе изучено поведение трибологической системы при различных временах остановки внешнего привода для различных времен релаксации параметра порядка. Полученные результаты расчета качественно совпадают с экспериментальными данными других авторов.
The thesis is devoted to the boundary friction processes investigation using thermodynamic model of ultrathin lubricant melting, which is grabbed between two atomically-smooth solid surfaces. The behavior of two simple mechanical analogues of tribological systems have been described: during the shearing of upper block in one direction and during the external periodical influence. It has been found out that depending on lubricant control parameters, regimes of dry, interrupted and sliding friction can be realized. Further thermodynamical potential modification allows us to describe first-order phase transition in the system. The presence of the elastic connection between block and external drive significantly changes temperature and shear velocity hysteresis’s. The universal dependence of viscosity of lubricant on temperature and velocity gradient has been took into consideration. Herewith, the lubricant characteristics have been investigated at the low temperatures and low shear velocities. The guasi-static friction force was described using the viscosity dependence. The further thermodynamic potential modification has been performed. For this purpose, the linear term was added in the free energy expansion into series. The critical values of lubricant melting and solidification were calculated for the phase transitions of the first- and second-order. The relation was found between expansion parameters for which first- or second-order phase transition are realized in the system. Obtained results qualitatively coincide with experimental data.
Küchemann, Stefan. "Thermodynamic and kinetic properties of metallic glasses during ultrafast heating". Doctoral thesis, 2014. http://hdl.handle.net/11858/00-1735-0000-0022-5FE2-B.
Texto completoAntonioli, John. "Compensation Functions for Shifts of Finite Type and a Phase Transition in the p-Dini Functions". Thesis, 2013. http://hdl.handle.net/1828/4896.
Texto completoGraduate
0405
antoniol@uvic.ca
Kherb, Jaibir. "Specific Cation Effects in Biological Systems: Thermodynamic and Spectroscopic Insights". Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10443.
Texto completoNowotny, Thomas. "Phase transitions and multifractal properties of random field Ising models". Doctoral thesis, 2001. https://ul.qucosa.de/id/qucosa%3A10924.
Texto completoIn this work random field Ising models with quenched dichotomous symmetric random field are considered for the one-dimensional case and on the Bethe lattice. To this end the canonical partition function is reformulated to the partition function of one spin in an effective field. In the first part of the work the multifractal spectrum of this effective field is investigated, transitions in the spectrum are explained and inequalities between local and global generalized fractal dimensions are proven which allow to characterize the multifractal spectrum bei various bounds. A further part of the work is dedicated to the characterization of the measure of the local magnetization which is obtained by convolution of the measure of the effective field with itself. In this context the convolution of multifractals is investigated in a more general setup and relations between the multifractal properties of the convolution and the multifractal properties of the convoluted measures are proven. The phase transition from ferro- to paramagnetismus for the model on the Bethe lattice is investigated in the third part of the thesis. Apart from improved exact bounds for the uniqueness of the paramagnetic state essentially three criteria for the transition are developped and numerically evaluated to determine the transition line. The multifractal properties of the effective field for the model on the Bethe lattice finally turn out to be trivial because the interesting dimensions do not exist.
Hubkowska-Kosińska, Katarzyna. "Elektrochemiczne właściwości stopów palladu z rutenem". Doctoral thesis, 2016. https://depotuw.ceon.pl/handle/item/1429.
Texto completoIn the framework of this dissertation the specific conditions of the electrochemical deposition of the palladium-ruthenium (Pd-Ru) alloys as limited volume electrodes (thin coatings deposited on the conducive substrate) were elaborated and their electrochemical properties were examined with the special emphasis on the process of hydrogen electrochemical absorption. Research included the influence of the potential value, alloy composition and temperature on the process of electrochemical sorption of hydrogen and surface oxidation. Pd-Ru alloys are particularly important in the context of its utilization in hybrid hydride cells, since – according to the results of this study – Pd-Ru alloys are able to store even 20% more hydrogen than the pure palladium. Until recently it has been thought that the addition of the other noble metal to the pure palladium could only result in the decrease in its hydrogen storage ability (with the exception of the Pd-Rh system). Furthermore in the literature, there is available only residual information on Pd-Ru alloys and none of articles concerns the electrochemical deposition and examination of detailed properties of Pd-Ru samples. Experiments that have been conducted, allowed to describe the conditions of deposition (galvanic baths compositions, deposition potentials) of 1 µm thick samples with reproducible compositions. Receiving samples of the indicated thickness gave ability to work with limited volume electrodes. This approach allowed to distinguish, in the detailed manner, the signals from the electrochemical processes taking place in the bulk and on the surface of the sample. Palladium-ruthenium alloys were analyzed with respect to two processes: (1) hydrogen absorption in the bulk (also with simultaneous hydrogen adsorption on the surface); (2) alloy surface oxidation. The first one is responsible for hydrogen absorbing properties (hydrogen storage), while the second one – for electrocatalytic properties (catalyst). Received results indicate that the applied electrochemical method of the alloys deposition gives ability to obtain successfully thin alloy layers in the wide range of compositions (homogeneous in the bulk, with the surface enrichment with Ru). Pd-Ru alloys were characterized with several physicochemical techniques, such as: scanning electron spectroscopy (SEM) with energy dispersive spectroscopy (EDS), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction and electrochemical techniques such as: chronoamperometry (CA), cyclic chronovoltammetry (CV), as well as electrochemical quartz crystal microbalance (EQCM). In the connection with the differences in the bulk and surface compositions of alloys the non-destructive method of surface composition estimation, based on the linear dependence of the surface composition (obtained from the X-ray photoelectron spectroscopy – XPS) and the reduction potential of surface oxides (received from the cyclic chronovoltammetry – CV), was proposed. Thereby only on the basis of CV data it is possible to obtain surface composition without the need of XPS analysis. In the framework of this dissertation the hypothesis, that not only Pd-Rh alloys are able to absorb more hydrogen than Pd, was confirmed. It was found that Pd-Ru alloys containing only 1% of Ru (in the bulk) are able to absorb 20% (maximum hydrogen to metal atomic ratio: H/M=0,88) more hydrogen than Pd (H/M=0,74). Pd-Ru alloys lose their ability to form hydrides already for samples containing only 7-8% of Ru. Alloying palladium with ruthenium allows also for facilitation of the process of hydrogen desorption as well as in the most cases for the reduction of hydrogen sorption time. Hydrogen sorption experiments conducted in temperature range 283-313 K gives ability to estimate the value of thermodynamic functions (the change of Gibbs energy, the change of enthalpy and the change of entropy) of hydrogen sorption. Calculated values of entropy changes indicate that in the crystal structure of alloy hydrogen occupies preferably Pd neigbouring interstices. Experiments performed by the use of the electrochemical quartz crystal microbalance indicates that both (even single) hydrogen absorption and Ru addition influence on the increase in alloy resistance on the electrochemical dissolution. EQCM experiments also allowed to determine the level of stresses (apparent molar mass) in the crystal lattice that accompanied the process of hydrogen absorption in Pd-Ru alloys. With the increase in the hydrogen content the magnitude of stresses in Pd-Ru alloys increase, wherein the maximum value of frequency (originating from stresses) decrease with the increase in Ru content in the sample. The course of hydrogen absorption-desorption curve did not overlap, what implies that the distribution of stresses varies depending on the type of the sorption process. Results of these studies provide missing and necessary information, which allows to describe in details properties of Pd-Ru alloys. I expect that the results of these experiments appeared to be helpful in the interpretation of the processes occurring on the electrode materials on the potential importance for hydride and fuel cells and electrochemical supercapacitors in the aspect of basic application issues. Obtained results can be helpful i.a. to design systems where tested material will cooperate with commercial hydrogen-absorbing alloys forming coupled system for hydrogen absorption and storage and will be successfully utilized as a catalyst in ethanol fuel cell, which becoming more and more important in the automotive and military industry. In the scientific literature the first few articles using the published results of the project have appeared. It provides proof of the validity of the conducted research and the topicality of taken subject.