Sample records for hydration phase diagram

  1. Gas Hydrate Stability and Sampling: The Future as Related to the Phase Diagram

    Directory of Open Access Journals (Sweden)

    E. Dendy Sloan


    Full Text Available The phase diagram for methane + water is explained, in relation to hydrate applications, such as in flow assurance and in nature. For natural applications, the phase diagram determines the regions for hydrate formation for two- and three-phase conditions. Impacts are presented for sample preparation and recovery. We discuss an international study for “Round Robin” hydrate sample preparation protocols and testing.

  2. A composite phase diagram of structure H hydrates using Schreinemakers' geometric approach (United States)

    Mehta, A.P.; Makogon, T.Y.; Burruss, R.C.; Wendlandt, R.F.; Sloan, E.D.


    A composite phase diagram is presented for Structure H (sH) clathrate hydrates. In this work, we derived the reactions occurring among the various phases along each four-phase (Ice/Liquid water, liquid hydrocarbon, vapor, and hydrate) equilibrium line. A powerful method (though seldom used in chemical engineering) for multicomponent equilibria developed by Schreinemakers is applied to determine the relative location of all quadruple (four-phase) lines emanating from three quintuple (five-phase) points. Experimental evidence validating the approximate phase diagram is also provided. The use of Schreinemakers' rules for the development of the phase diagram is novel for hydrates, but these rules may be extended to resolve the phase space of other more complex systems commonly encountered in chemical engineering.

  3. Molecular Simulation of the Phase Diagram of Methane Hydrate: Free Energy Calculations, Direct Coexistence Method, and Hyperparallel Tempering. (United States)

    Jin, Dongliang; Coasne, Benoit


    Different molecular simulation strategies are used to assess the stability of methane hydrate under various temperature and pressure conditions. First, using two water molecular models, free energy calculations consisting of the Einstein molecule approach in combination with semigrand Monte Carlo simulations are used to determine the pressure-temperature phase diagram of methane hydrate. With these calculations, we also estimate the chemical potentials of water and methane and methane occupancy at coexistence. Second, we also consider two other advanced molecular simulation techniques that allow probing the phase diagram of methane hydrate: the direct coexistence method in the Grand Canonical ensemble and the hyperparallel tempering Monte Carlo method. These two direct techniques are found to provide stability conditions that are consistent with the pressure-temperature phase diagram obtained using rigorous free energy calculations. The phase diagram obtained in this work, which is found to be consistent with previous simulation studies, is close to its experimental counterpart provided the TIP4P/Ice model is used to describe the water molecule.

  4. Phosphatidylcholine: cholesterol phase diagrams. (United States)

    Thewalt, J L; Bloom, M


    Two mono-cis-unsaturated phosphatidylcholine (PC) lipid molecules, having very different gel-liquid crystalline phase transition temperatures as a consequence of the relative positions of the double bond, exhibit PC:cholesterol phase diagrams that are very similar to each other and to that obtained previously for a fully saturated PC:cholesterol mixture (Vist, M. R., and J. H. Davis. 1990. Biochemistry 29:451-464). This leads to the conjecture that PC:cholesterol membrane phase diagrams have a universal form which is relatively independent of the precise chemical structure of the PC molecule. One feature of this phase diagram is the observation over a wide temperature range of a fluid but highly conformationally ordered phase at bilayer concentrations of more than approximately 25 mol% cholesterol. This ;liquid ordered' phase is postulated to be the relevant physical state for many biological membranes, such as the plasma membrane of eukaryotic cells, that contain substantial amounts of cholesterol or equivalent sterols.

  5. Engineering Holographic Superconductor Phase Diagrams


    Chen, Jiunn-Wei; Dai, Shou-Huang; Maity, Debaprasad; Zhang, Yun-Long


    We study how to engineer holographic models with features of a high temperature superconductor phase diagram. We introduce a field in the bulk which provides a tunable "doping" parameter in the boundary theory. By designing how this field changes the effective masses of other order parameter fields, desired phase diagrams can be engineered. We give examples of generating phase diagrams with phase boundaries similar to a superconducting dome and an anti-ferromagnetic phase by including two ord...

  6. Phase diagrams for sonoluminescing bubbles

    NARCIS (Netherlands)

    Hilgenfeldt, Sascha; Lohse, Detlef; Brenner, Michael P.


    Sound driven gas bubbles in water can emit light pulses. This phenomenon is called sonoluminescence (SL). Two different phases of single bubble SL have been proposed: diffusively stable and diffusively unstable SL. We present phase diagrams in the gas concentration versus forcing pressure state

  7. Phase diagrams and crystal growth (United States)

    Venkrbec, Jan


    Phase diagrams are briefly treated as generalized property-composition relationships, with respect to crystal technology optimization. The treatment is based on mutual interaction of three systems related to semiconductors: (a) the semiconducting material systems, (b0 the data bank, (c) the system of crystallization methods. A model is proposed enabling optimatization on the path from application requirements to the desired material. Further, several examples of the selection as to the composition of LED and laser diode material are given. Some of molten-solution-zone methods are being successfully introduced for this purpose. Common features of these methods, the application of phase diagrams, and their pecularities compared with other crystallization methods are illustrated by schematic diagrams and by examples. LPE methods, particularly the steady-state LPE methods such as Woodall's ISM and Nishizawa's TDM-CVP, and the CAM-S (Crystallization Method Providing Composition Autocontrol in Situ) have been chosen as examples. Another approach of exploiting phase diagrams for optimal material selection and for determination of growth condition before experimentation through a simple calculation is presented on InP-GaP solid solutions. Ternary phase diagrams are visualized in space through calculation and constructions based on the corresponding thermodynamic models and anaglyphs. These make it easy to observe and qualitatively analyze the crystallization of every composition. Phase diagrams can be also used as a powerful tool for the deduction of new crystallization methods. Eutectic crystallization is an example of such an approach where a modified molten-solution-zone method can give a sandwich structure with an abrupt concentration change. The concentration of a component can range from 0 to 100% in the different solid phases.

  8. Phase diagram of Hertzian spheres

    NARCIS (Netherlands)

    Pàmies, J.C.; Cacciuto, A.; Frenkel, D.


    We report the phase diagram of interpenetrating Hertzian spheres. The Hertz potential is purely repulsive, bounded at zero separation, and decreases monotonically as a power law with exponent 5/2, vanishing at the overlapping threshold. This simple functional describes the elastic interaction of

  9. Phase diagram of boron crystals (United States)

    Shirai, Koun


    The current status of study on the phase diagram of boron is given from the theoretical viewpoint. Boron is the last elemental crystal whose phase diagram is missing. In the last decade, several new structures of boron allotropes were found, while some were disproven. Presently, even the number of allotropes of boron is uncertain. A simple reason for this is that there are many and complicated structures, and some are minimally different from the others. A theoretical study thus requires very high accuracy. The difficulty, however, is not merely a technical difficulty of computational scale. The physics involved is quite different from what is obtained by band theory, which is the most successful theory of solids. It is only recent that a fundamental problem of metal/insulator has been solved. We come to know that the interrelationships between nonstoichiometry, partially occupied sites, and the balance of intra/inter-icosahedral bonding, which were considered to be uncorrelated properties, inevitably determine the relative stability of various structures. The configuration of the defects in boron crystals is not capricious but there is some correlation among the defects. Many problems were solved on this ground, and contributed to the creation of the phase diagram. However, there are still many unsolved problems and some newly arose. In particular, for the tetragonal phase, sharp discrepancies are present in both experiment and theory. Thus, the problem of tetragonal phase is described in more detail. From the viewpoint of material research, the phase diagram provides the basis for searching new materials. State-of-the-art methods of structural prediction have stimulated researchers’ interest.

  10. Phase diagrams for surface alloys

    DEFF Research Database (Denmark)

    Christensen, Asbjørn; Ruban, Andrei; Stoltze, Per


    of the heat of segregation from the bulk and the sign of the excess interactions between the atoms in the surface (the surface mixing energy). We also consider the more complicated cases a with ordered surface phases, nonpseudomorphic overlayers, second layer segregation, and multilayers. The discussion......We discuss surface alloy phases and their stability based on surface phase diagrams constructed from the surface energy as a function of the surface composition. We show that in the simplest cases of pseudomorphic overlayers there are four generic classes of systems, characterized by the sign...... is based on density-functional calculations using the coherent-potential approximation and on effective-medium theory. We give self-consistent density-functional results for the segregation energy and surface mixing energy for all combinations of the transition and noble metals. Finally we discuss...

  11. High temperature phase equilibria and phase diagrams

    CERN Document Server

    Kuo, Chu-Kun; Yan, Dong-Sheng


    High temperature phase equilibria studies play an increasingly important role in materials science and engineering. It is especially significant in the research into the properties of the material and the ways in which they can be improved. This is achieved by observing equilibrium and by examining the phase relationships at high temperature. The study of high temperature phase diagrams of nonmetallic systems began in the early 1900s when silica and mineral systems containing silica were focussed upon. Since then technical ceramics emerged and more emphasis has been placed on high temperature

  12. Metastable phases and 'metastable' phase diagrams (United States)

    Brazhkin, V. V.


    The work discusses the qualitative nature of phase transitions for metastable states of substances. The objects of the physics of condensed media are primarily the equilibrium states of substances with metastable phases viewed as an exception, while in chemistry the overwhelming majority of organic substances under investigation are metastable. It turns out that at normal pressure many simple molecular compounds based on light elements (these include: most hydrocarbons; nitrogen oxides, hydrates, and carbides; carbon oxide (CO); alcohols, glycerin) are metastable substances too, i.e. they do not match the Gibbs free energy minimum for a given atomic chemical composition. At moderate temperatures and pressures, the phase transitions for particular metastable phases are reversible throughout the entire experimentally accessible time period with the equilibrium thermodynamics laws obeyed. At sufficiently high pressures (1-10 GPa), most molecular phases irreversibly transform to more energy efficient polymerized phases. These transformations are not consistent with the equality of the Gibbs free energies between the phases before and after transition, i.e. they are not phase transitions in the 'classical' meaning. The resulting polymeric phases at normal pressure can exist at temperatures above the melting one for an initial metastable molecular phase. Striking examples of such polymers are polyethylene and a polymerized modification of CO. Many energy-intermediate polymeric phases can apparently be synthesized by the 'classical' chemistry techniques at normal pressure. At higher pressures (10-100 GPa) polymerized modifications transform to a mixture of simple stable phases.

  13. Stereo 3D spatial phase diagrams

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Jinwu, E-mail:; Liu, Baicheng, E-mail:


    Phase diagrams serve as the fundamental guidance in materials science and engineering. Binary P-T-X (pressure–temperature–composition) and multi-component phase diagrams are of complex spatial geometry, which brings difficulty for understanding. The authors constructed 3D stereo binary P-T-X, typical ternary and some quaternary phase diagrams. A phase diagram construction algorithm based on the calculated phase reaction data in PandaT was developed. And the 3D stereo phase diagram of Al-Cu-Mg ternary system is presented. These phase diagrams can be illustrated by wireframe, surface, solid or their mixture, isotherms and isopleths can be generated. All of these can be displayed by the three typical display ways: electronic shutter, polarization and anaglyph (for example red-cyan glasses). Especially, they can be printed out with 3D stereo effect on paper, and watched by the aid of anaglyph glasses, which makes 3D stereo book of phase diagrams come to reality. Compared with the traditional illustration way, the front of phase diagrams protrude from the screen and the back stretches far behind of the screen under 3D stereo display, the spatial structure can be clearly and immediately perceived. These 3D stereo phase diagrams are useful in teaching and research. - Highlights: • Stereo 3D phase diagram database was constructed, including binary P-T-X, ternary, some quaternary and real ternary systems. • The phase diagrams can be watched by active shutter or polarized or anaglyph glasses. • The print phase diagrams retains 3D stereo effect which can be achieved by the aid of anaglyph glasses.

  14. Phase diagram of ammonium nitrate

    Energy Technology Data Exchange (ETDEWEB)

    Dunuwille, Mihindra; Yoo, Choong-Shik, E-mail: [Department of Chemistry and Institute for Shock Physics, Washington State University, Pullman, Washington 99164 (United States)


    Ammonium Nitrate (AN) is a fertilizer, yet becomes an explosive upon a small addition of chemical impurities. The origin of enhanced chemical sensitivity in impure AN (or AN mixtures) is not well understood, posing significant safety issues in using AN even today. To remedy the situation, we have carried out an extensive study to investigate the phase stability of AN and its mixtures with hexane (ANFO–AN mixed with fuel oil) and Aluminum (Ammonal) at high pressures and temperatures, using diamond anvil cells (DAC) and micro-Raman spectroscopy. The results indicate that pure AN decomposes to N{sub 2}, N{sub 2}O, and H{sub 2}O at the onset of the melt, whereas the mixtures, ANFO and Ammonal, decompose at substantially lower temperatures. The present results also confirm the recently proposed phase IV-IV{sup ′} transition above 17 GPa and provide new constraints for the melting and phase diagram of AN to 40 GPa and 400°C.

  15. Ferroelectric phase diagram of PVDF:PMMA

    NARCIS (Netherlands)

    Li, M.; Stingelin, N.; Michels, J.J.; Spijkman, M.-J.; Asadi, K.; Feldman, K.; Blom, P.W.M.; Leeuw, D.M. de


    We have investigated the ferroelectric phase diagram of poly(vinylidene fluoride) (PVDF) and poly(methyl methacrylate) (PMMA). The binary nonequilibrium temperature composition diagram was determined and melting of α- and β-phase PVDF was identified. Ferroelectric β-PVDF:PMMA blend films were made

  16. Ferroelectric Phase Diagram of PVDF : PMMA

    NARCIS (Netherlands)

    Li, Mengyuan; Stingelin, Natalie; Michels, Jasper J.; Spijkman, Mark-Jan; Asadi, Kamal; Feldman, Kirill; Blom, Paul W. M.; de Leeuw, Dago M.


    We have investigated the ferroelectric phase diagram of poly(vinylidene fluoride) (PVDF) and poly(methyl methacrylate) (PMMA). The binary nonequilibrium temperature composition diagram was determined and melting of alpha- and beta-phase PVDF was identified. Ferroelectric beta-PVDF:PMMA blend films

  17. Phase diagram of spiking neural networks. (United States)

    Seyed-Allaei, Hamed


    In computer simulations of spiking neural networks, often it is assumed that every two neurons of the network are connected by a probability of 2%, 20% of neurons are inhibitory and 80% are excitatory. These common values are based on experiments, observations, and trials and errors, but here, I take a different perspective, inspired by evolution, I systematically simulate many networks, each with a different set of parameters, and then I try to figure out what makes the common values desirable. I stimulate networks with pulses and then measure their: dynamic range, dominant frequency of population activities, total duration of activities, maximum rate of population and the occurrence time of maximum rate. The results are organized in phase diagram. This phase diagram gives an insight into the space of parameters - excitatory to inhibitory ratio, sparseness of connections and synaptic weights. This phase diagram can be used to decide the parameters of a model. The phase diagrams show that networks which are configured according to the common values, have a good dynamic range in response to an impulse and their dynamic range is robust in respect to synaptic weights, and for some synaptic weights they oscillates in α or β frequencies, independent of external stimuli.

  18. Phase Diagrams of Strongly Interacting Theories

    DEFF Research Database (Denmark)

    Sannino, Francesco


    We summarize the phase diagrams of SU, SO and Sp gauge theories as function of the number of flavors, colors, and matter representation as well as the ones of phenomenologically relevant chiral gauge theories such as the Bars-Yankielowicz and the generalized Georgi-Glashow models. We finally report...

  19. Uranium phase diagram from first principles (United States)

    Yanilkin, Alexey; Kruglov, Ivan; Migdal, Kirill; Oganov, Artem; Pokatashkin, Pavel; Sergeev, Oleg


    The work is devoted to the investigation of uranium phase diagram up to pressure of 1 TPa and temperature of 15 kK based on density functional theory. First of all the comparison of pseudopotential and full potential calculations is carried out for different uranium phases. In the second step, phase diagram at zero temperature is investigated by means of program USPEX and pseudopotential calculations. Stable and metastable structures with close energies are selected. In order to obtain phase diagram at finite temperatures the preliminary selection of stable phases is made by free energy calculation based on small displacement method. For remaining candidates the accurate values of free energy are obtained by means of thermodynamic integration method (TIM). For this purpose quantum molecular dynamics are carried out at different volumes and temperatures. Interatomic potentials based machine learning are developed in order to consider large systems and long times for TIM. The potentials reproduce the free energy with the accuracy 1-5 meV/atom, which is sufficient for prediction of phase transitions. The equilibrium curves of different phases are obtained based on free energies. Melting curve is calculated by modified Z-method with developed potential.

  20. Phase diagram of KHF2 and non-equilibrium effects (United States)

    Hobson, M. C.; Kellner, J. D.


    The equilibrium diagram for the KHF2-H2O system was constructed from cooling and heating curves for the compositions between 5 wt% and 40 wt% KHF2 and the results are shown. The phase diagrams shown is typical of that of a two component system with miscible liquid phases and whole solid phases consist of pure components. A eutectic point was found at approximately 15% KHF2 which remains completely liquid down to a temperature of -9.0 C. No hydrate formation was observed and no anomalous behavior such as the occurrence of solid transitions or metastable states was observed. The effect of rapid freezing on the equilibrium diagram did not appear, and cooling curves exhibited only one halt. Also, at rapid freezing rates, the supercooling of the solutions was smaller than those observed at the slow cooling rates. The existence of a eutectic composition and the slow rate of dissolution of the salt are used to interpret heat absorption behavior in practical applications of the KHF2-H2O system.

  1. Phase diagram of nucleosome core particles. (United States)

    Mangenot, S; Leforestier, A; Durand, D; Livolant, F


    We present a phase diagram of the nucleosome core particle (NCP) as a function of the monovalent salt concentration and applied osmotic pressure. Above a critical pressure, NCPs stack on top of each other to form columns that further organize into multiple columnar phases. An isotropic (and in some cases a nematic) phase of columns is observed in the moderate pressure range. Under higher pressure conditions, a lamello-columnar phase and an inverse hexagonal phase form under low salt conditions, whereas a 2D hexagonal phase or a 3D orthorhombic phase is found at higher salt concentration. For intermediate salt concentrations, microphase separation occurs. The richness of the phase diagram originates from the heterogeneous distribution of charges at the surface of the NCP, which makes the particles extremely sensitive to small ionic variations of their environment, with consequences on their interactions and supramolecular organization. We discuss how the polymorphism of NCP supramolecular organization may be involved in chromatin changes in the cellular context.

  2. Hydration states of AFm cement phases

    Energy Technology Data Exchange (ETDEWEB)

    Baquerizo, Luis G., E-mail: [Innovation, Holcim Technology Ltd., CH-5113 Holderbank (Switzerland); Matschei, Thomas [Innovation, Holcim Technology Ltd., CH-5113 Holderbank (Switzerland); Scrivener, Karen L. [Laboratory of Construction Materials, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland); Saeidpour, Mahsa; Wadsö, Lars [Building Materials, Lund University, Box 124, 221 000 Lund (Sweden)


    The AFm phase, one of the main products formed during the hydration of Portland and calcium aluminate cement based systems, belongs to the layered double hydrate (LDH) family having positively charged layers and water plus charge-balancing anions in the interlayer. It is known that these phases present different hydration states (i.e. varying water content) depending on the relative humidity (RH), temperature and anion type, which might be linked to volume changes (swelling and shrinkage). Unfortunately the stability conditions of these phases are insufficiently reported. This paper presents novel experimental results on the different hydration states of the most important AFm phases: monocarboaluminate, hemicarboaluminate, strätlingite, hydroxy-AFm and monosulfoaluminate, and the thermodynamic properties associated with changes in their water content during absorption/desorption. This data opens the possibility to model the response of cementitious systems during drying and wetting and to engineer systems more resistant to harsh external conditions.

  3. Topological phase diagram of superconducting carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Milz, Lars; Marganska-Lyzniak, Magdalena; Grifoni, Milena [Institut I - Theoretische Physik Universitaet Regensburg (Germany)


    The topological superconducting phase diagram of superconducting carbon nanotubes is discussed. Under the assumption of a short-ranged pairing potential, there are two spin-singlet states: an s-wave and an exotic p + ip-wave that are possible because of the special structure of the honeycomb lattice. The consequences for the possible presence of Majorana edge states in carbon nanotubes are addressed. In particular, regions in the magnetic field-chemical potential plane possibly hosting localized Majorana modes are discussed.

  4. Phase Diagram of Spiking Neural Networks

    Directory of Open Access Journals (Sweden)

    Hamed eSeyed-Allaei


    Full Text Available In computer simulations of spiking neural networks, often it is assumed that every two neurons of the network are connected by a probablilty of 2%, 20% of neurons are inhibitory and 80% are excitatory. These common values are based on experiments, observations. but here, I take a different perspective, inspired by evolution. I simulate many networks, each with a different set of parameters, and then I try to figure out what makes the common values desirable by nature. Networks which are configured according to the common values, have the best dynamic range in response to an impulse and their dynamic range is more robust in respect to synaptic weights. In fact, evolution has favored networks of best dynamic range. I present a phase diagram that shows the dynamic ranges of different networks of different parameteres. This phase diagram gives an insight into the space of parameters -- excitatory to inhibitory ratio, sparseness of connections and synaptic weights. It may serve as a guideline to decide about the values of parameters in a simulation of spiking neural network.

  5. Gas hydrate phase equilibria measurement techniques and phase rule considerations

    Energy Technology Data Exchange (ETDEWEB)

    Beltran, Juan G. [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, ON (Canada); Bruusgaard, Hallvard [Department of Chemical Engineering, McGill University, Montreal, QC (Canada); Servio, Phillip, E-mail: [Department of Chemical Engineering, McGill University, Montreal, QC (Canada)


    Highlights: > Inconsistencies found in hydrate literature. > Clarification to the number of variables needed to satisfy and justify equilibrium data. > Application of phase rule to mixed hydrate systems. > Thermodynamically consistent format to present data. - Abstract: A brief review of the Gibbs phase rule for non-reacting systems and its correct application to clathrate hydrates is presented. Clarification is provided for a common mistake found in hydrate phase-equilibria literature, whereby initial compositions are used as intensive variables to satisfy the Gibbs phase rule instead of the equilibrium values. The system of (methane + carbon dioxide + water) under (hydrate + liquid + vapor) equilibrium is used as a case study to illustrate key points and suggestions to improve experimental techniques are proposed.

  6. Cu-Zn binary phase diagram and diffusion couples (United States)

    Mccoy, Robert A.


    The objectives of this paper are to learn: (1) what information a binary phase diagram can yield; (2) how to construct and heat treat a simple diffusion couple; (3) how to prepare a metallographic sample; (4) how to operate a metallograph; (5) how to correlate phases found in the diffusion couple with phases predicted by the phase diagram; (6) how diffusion couples held at various temperatures could be used to construct a phase diagram; (7) the relation between the thickness of an intermetallic phase layer and the diffusion time; and (8) the effect of one species of atoms diffusing faster than another species in a diffusion couple.

  7. Lattice investigations of the QCD phase diagram

    Energy Technology Data Exchange (ETDEWEB)

    Guenther, Jana


    To understand the physics in the early universe as well as in heavy ion collisions a throughout understanding of the theory of strong interaction, quantum chromodynamics (QCD), is important. Lattice QCD provides a tool to study it from first principles. However due to the sign problem direct simulations with physical conditions are at the moment limited to zero chemical potential. In this thesis I present a circumvention of this problem. We can gain information on the QCD phase diagram and the equation of state from analytical continuation of results extracted from simulations at imaginary chemical potential. The topological susceptibility is very expensive to compute in Lattice QCD. However it provides an important ingredient for the estimation of the axion mass. The axion is a possible candidate for a dark matter, which plays in important role in the understanding of our universe. In this thesis I discuss two techniques that make it possible to determine the topological susceptibility and allow for an estimation of the axion mass. I then use this mass restrain to analyze the idea of an experiment to detect axions with a dielectric mirror.

  8. Phase diagram of Nitrogen at high pressures and temperatures (United States)

    Jenei, Zsolt; Lin, Jung-Fu; Yoo, Choong-Shik


    Nitrogen is a typical molecular solid with relatively weak van der Waals intermolecular interactions but strong intramolecular interaction arising from the second highest binding energy of all diatomic molecules. The phase diagram of solid nitrogen is, however, complicated at high pressures, as inter-molecular interaction becomes comparable to the intra-molecular interaction. In this paper, we present an updated phase diagram of the nitrogen in the pressure-temperature region of 100 GPa and 1000 K, based on in-situ Raman and synchrotron x-ray diffraction studies using externally heated membrane diamond anvil cells. While providing an extension of the phase diagram, our results indicate a ``steeper'' slope of the δ/ɛ phase boundary than previously determined^1. We also studied the stability of the ɛ phase at high pressures and temperatures. Our new experimental results improve the understanding of the Nitrogen phase diagram. 1. Gregoryanz et al, Phys. Rev. B 66, 224108 (2002)

  9. Nitrogen-assisted Three-phase Equilibrium in Hydrate Systems Composed of Water, Methane, Carbon Dioxide, and Nitrogen (United States)

    Darnell, K.; Flemings, P. B.; DiCarlo, D. A.


    Guest molecule exchange is a new and promising methane hydrate production technique in which methane gas is produced by injection of another gas without requiring depressurization or thermal stimulation. The technique is generally associated with injection of carbon dioxide, but injection of nitrogen and carbon dioxide mixtures are the most efficient and economical. However, thermodynamic behavior of injection mixtures is poorly understood, and it is unclear how nitrogen affects the exchange process. Here, we describe thermodynamic stability of hydrate systems that contain water, methane, carbon dioxide, and nitrogen. We present a series of ternary and quaternary phase diagrams and show the impact nitrogen has on hydrate stability. Our results demonstrate that nitrogen can either stabilize hydrate, de-stabilize hydrate, or produce three-phase equilibrium (gas, water, and hydrate) depending on its relative abundance. At low abundance nitrogen forms hydrate and directly contributes to the exchange process. At high abundance nitrogen de-stabilizes hydrate akin to traditional hydrate inhibitors, such as salt, alcohol, or mono-ethylene glycol. We show how the dual properties of nitrogen lead to three-phase equilibrium and how three-phase equilibrium may explain much of the behavior observed in methane production from nitrogen-rich injections. We apply our analysis to laboratory experiments and the methane hydrate field test on the northern Alaskan slope at Ignik Sikumi. These results can be extended to analyze dynamic evolution of mixed hydrate systems.

  10. Infrared thermography method for fast estimation of phase diagrams

    Energy Technology Data Exchange (ETDEWEB)

    Palomo Del Barrio, Elena [Université de Bordeaux, Institut de Mécanique et d’Ingénierie, Esplanade des Arts et Métiers, 33405 Talence (France); Cadoret, Régis [Centre National de la Recherche Scientifique, Institut de Mécanique et d’Ingénierie, Esplanade des Arts et Métiers, 33405 Talence (France); Daranlot, Julien [Solvay, Laboratoire du Futur, 178 Av du Dr Schweitzer, 33608 Pessac (France); Achchaq, Fouzia, E-mail: [Université de Bordeaux, Institut de Mécanique et d’Ingénierie, Esplanade des Arts et Métiers, 33405 Talence (France)


    Highlights: • Infrared thermography is proposed to determine phase diagrams in record time. • Phase boundaries are detected by means of emissivity changes during heating. • Transition lines are identified by using Singular Value Decomposition techniques. • Different binary systems have been used for validation purposes. - Abstract: Phase change materials (PCM) are widely used today in thermal energy storage applications. Pure PCMs are rarely used because of non adapted melting points. Instead of them, mixtures are preferred. The search of suitable mixtures, preferably eutectics, is often a tedious and time consuming task which requires the determination of phase diagrams. In order to accelerate this screening step, a new method for estimating phase diagrams in record time (1–3 h) has been established and validated. A sample composed by small droplets of mixtures with different compositions (as many as necessary to have a good coverage of the phase diagram) deposited on a flat substrate is first prepared and cooled down to ambient temperature so that all droplets crystallize. The plate is then heated at constant heating rate up to a sufficiently high temperature for melting all the small crystals. The heating process is imaged by using an infrared camera. An appropriate method based on singular values decomposition technique has been developed to analyze the recorded images and to determine the transition lines of the phase diagram. The method has been applied to determine several simple eutectic phase diagrams and the reached results have been validated by comparison with the phase diagrams obtained by Differential Scanning Calorimeter measurements and by thermodynamic modelling.

  11. Phase diagrams for geoscientists an atlas of the Earth's interior

    CERN Document Server

    Gasparik, Tibor


    Presented in this new, full-color edition, with the first polychrome phase diagrams to be published, this geoscientific atlas is backed by the author's unrivalled dataset, and amounts to the most complete survey yet of phase relations in Earth's chemistry.

  12. Reexamination of Kerker's conditions by means of the phase diagram (United States)

    Lee, Jeng Yi; Miroshnichenko, Andrey E.; Lee, Ray-Kuang


    For passive electromagnetic scatterers, we explore a variety of extreme limits on directional scattering patterns in a phase diagram, regardless of the details on the geometric configurations and material properties. By demonstrating the extinction cross sections with the power conservation intrinsically embedded in the phase diagram, we give an alternative interpretation for Kerker's first and second conditions, associated with zero backward scattering (ZBS) and nearly zero forward scattering (NZFS). Physical boundaries and limitations for these directional radiations are illustrated along with a generalized Kerker's condition with implicit parameters. By taking the dispersion relations of gold silicon core-shell nanoparticles into account, we reveal the realistic parameters to experimentally implement ZBS and NZFS at optical frequencies by means of a phase diagram.

  13. Phase diagrams of low-density polyethylene-alkylbenzene systems (United States)

    Ilyasova, A. N.; Kudryavtsev, Y. V.; Lebedeva, T. N.; Levashova, I. V.; Flyagina, Yu. A.; Pochivalov, K. V.


    Complete phase diagrams for mixtures of low-density polyethylene with p- and m-xylene are plotted by optical means in developing the concept of which partially crystalline polymers are microstructured liquids. It is shown that in contrast to the ones presented in the literature, both diagrams contain the solubility boundary curve of the low-molecular weight component in the polymer, above which the polyethylene has the structure of a single-phase gel (crosslinks formed by crystallites and amorphous regions saturated with xylene). At the figurative point on the diagrams, a situation is observed in which the dissolution of all the liquid contained in the initial two-phase system in the polymer is accompanied by its simultaneous complete amorphization. The parameters of the figurative point allow us to estimate the thermodynamic affinity of different alkylbenzenes toward polyethylene.

  14. Pressure induced reactions amongst calcium aluminate hydrate phases

    KAUST Repository

    Moon, Ju-hyuk


    The compressibilities of two AFm phases (strätlingite and calcium hemicarboaluminate hydrate) and hydrogarnet were obtained up to 5 GPa by using synchrotron high-pressure X-ray powder diffraction with a diamond anvil cell. The AFm phases show abrupt volume contraction regardless of the molecular size of the pressure-transmitting media. This volume discontinuity could be associated to a structural transition or to the movement of the weakly bound interlayer water molecules in the AFm structure. The experimental results seem to indicate that the pressure-induced dehydration is the dominant mechanism especially with hygroscopic pressure medium. The Birch-Murnaghan equation of state was used to compute the bulk modulus of the minerals. Due to the discontinuity in the pressure-volume diagram, a two stage bulk modulus of each AFm phase was calculated. The abnormal volume compressibility for the AFm phases caused a significant change to their bulk modulus. The reliability of this experiment is verified by comparing the bulk modulus of hydrogarnet with previous studies. © 2011 Elsevier Ltd. All rights reserved.

  15. Magnetic phase diagram of Ho/Er alloys

    DEFF Research Database (Denmark)

    Cowley, R.A.; Simpson, J.A.; Bryn-Jacobsen, C.


    are found, arising from the competition between the exchange and anisotropic crystal-field interactions, the latter of which are of opposite sign for Ho and Er. The magnetic phase diagram has five distinct phases with long-range magnetic order: basal-plane helical, tilted helical, cycloidal, c......-axis longitudinally modulated, and conical. The cycloid and tilted helix have both incommensurate and commensurate q = 1/4c* forms, and all of the thin films have a conical structure at low temperatures, even though corresponding films of pure Ho and Er do not exhibit this phase. There is a pentacritical point......, and probably a disordered phase which is completely surrounded in the phase diagram by magnetic phases with long-range order. A Landau theory is developed to describe these results....

  16. Phase diagram of compressively strained nickelate thin films

    Directory of Open Access Journals (Sweden)

    A. S. Disa


    Full Text Available The complex phase diagrams of strongly correlated oxides arise from the coupling between physical and electronic structure. This can lead to a renormalization of the phase boundaries when considering thin films rather than bulk crystals due to reduced dimensionality and epitaxial strain. The well-established bulk RNiO3 phase diagram shows a systematic dependence between the metal-insulator transition and the perovskite A-site rare-earth ion, R. Here, we explore the equivalent phase diagram for nickelate thin films under compressive epitaxial strain. We determine the metal-insulator phase diagram for the solid solution of Nd1-yLayNiO3 thin films within the range 0 ≤ y ≤ 1. We find qualitative similarity between the films and their bulk analogs, but with an overall renormalization in the metal-insulator transition to lower temperature. A combination of x-ray diffraction measurements and soft x-ray absorption spectroscopy indicates that the renormalization is due to increased Ni–O bond hybridization for coherently strained thin films.

  17. Phase diagram for droplet impact on superheated surfaces

    NARCIS (Netherlands)

    Staat, Erik-Jan; Tran, Tuan; Geerdink, B.M.; Riboux, G.; Sun, Chao; Gordillo, J.M.; Lohse, Detlef


    We experimentally determine the phase diagram for impacting ethanol droplets on a smooth, sapphire surface in the parameter space of Weber number We versus surface temperature T. We observe two transitions, namely the one towards splashing (disintegration of the droplet) with increasing We, and the

  18. Phase Stability Diagrams for High Temperature Corrosion Processes

    Directory of Open Access Journals (Sweden)

    J. J. Ramos-Hernandez


    Full Text Available Corrosion phenomena of metals by fused salts depend on chemical composition of the melt and environmental conditions of the system. Detail knowledge of chemistry and thermodynamic of aggressive species formed during the corrosion process is essential for a better understanding of materials degradation exposed to high temperature. When there is a lack of kinetic data for the corrosion processes, an alternative to understand the thermodynamic behavior of chemical species is to utilize phase stability diagrams. Nowadays, there are several specialized software programs to calculate phase stability diagrams. These programs are based on thermodynamics of chemical reactions. Using a thermodynamic data base allows the calculation of different types of phase diagrams. However, sometimes it is difficult to have access to such data bases. In this work, an alternative way to calculate phase stability diagrams is presented. The work is exemplified in the Na-V-S-O and Al-Na-V-S-O systems. This system was chosen because vanadium salts is one of the more aggressive system for all engineering alloys, especially in those processes where fossil fuels are used.

  19. Investigating the QCD phase diagram with hadron multiplicities at NICA

    Energy Technology Data Exchange (ETDEWEB)

    Becattini, F. [Universita di Firenze (Italy); INFN, Firenze (Italy); Stock, R. [Goethe University, Frankfurt am Main (Germany)


    We discuss the potential of the experimental programme at NICA to investigate the QCD phase diagram and particularly the position of the critical line at large baryon-chemical potential with accurate measurements of particle multiplicities. We briefly review the present status and we outline the tasks to be accomplished both theoretically and the experimentally to make hadronic abundances a sensitive probe. (orig.)

  20. Phase diagram of matrix compressed sensing (United States)

    Schülke, Christophe; Schniter, Philip; Zdeborová, Lenka


    In the problem of matrix compressed sensing, we aim to recover a low-rank matrix from a few noisy linear measurements. In this contribution, we analyze the asymptotic performance of a Bayes-optimal inference procedure for a model where the matrix to be recovered is a product of random matrices. The results that we obtain using the replica method describe the state evolution of the Parametric Bilinear Generalized Approximate Message Passing (P-BiG-AMP) algorithm, recently introduced in J. T. Parker and P. Schniter [IEEE J. Select. Top. Signal Process. 10, 795 (2016), 10.1109/JSTSP.2016.2539123]. We show the existence of two different types of phase transition and their implications for the solvability of the problem, and we compare the results of our theoretical analysis to the numerical performance reached by P-BiG-AMP. Remarkably, the asymptotic replica equations for matrix compressed sensing are the same as those for a related but formally different problem of matrix factorization.

  1. Phase Diagrams of Electrostatically Self-Assembled Amphiplexes

    Energy Technology Data Exchange (ETDEWEB)

    V Stanic; M Mancuso; W Wong; E DiMasi; H Strey


    We present the phase diagrams of electrostatically self-assembled amphiplexes (ESA) comprised of poly(acrylic acid) (PAA), cetyltrimethylammonium chloride (CTACl), dodecane, pentanol, and water at three different NaCl salt concentrations: 100, 300, and 500 mM. This is the first report of phase diagrams for these quinary complexes. Adding a cosurfactant, we were able to swell the unit cell size of all long-range ordered phases (lamellar, hexagonal, Pm3n, Ia3d) by almost a factor of 2. The added advantage of tuning the unit cell size makes such complexes (especially the bicontinuous phases) attractive for applications in bioseparation, drug delivery, and possibly in oil recovery.

  2. Magnetic phase diagrams of classical triangular and kagome antiferromagnets

    Energy Technology Data Exchange (ETDEWEB)

    Gvozdikova, M V [Department of Physics, Kharkov National University, 61077 Kharkov (Ukraine); Melchy, P-E; Zhitomirsky, M E, E-mail: [Service de Physique Statistique, Magnetisme et Supraconductivite, UMR-E9001 CEA-INAC/UJF, 17 rue des Martyrs, 38054 Grenoble (France)


    We investigate the effect of geometrical frustration on the H-T phase diagrams of the classical Heisenberg antiferromagnets on triangular and kagome lattices. The phase diagrams for the two models are obtained from large-scale Monte Carlo simulations. For the kagome antiferromagnet, thermal fluctuations are unable to lift degeneracy completely and stabilize translationally disordered multipolar phases. We find a substantial difference in the temperature scales of the order by disorder effect related to different degeneracy of the low- and the high-field classical ground states in the kagome antiferromagnet. In the low-field regime, the Kosterlitz-Thouless transition into a spin-nematic phase is produced by unbinding of half-quantum vortices.

  3. Phase diagram of the lattice SU(2) Higgs model

    Energy Technology Data Exchange (ETDEWEB)

    Bonati, C., E-mail: bonati@df.unipi.i [Dipartimento di Fisica and INFN, Pisa (Italy); Cossu, G., E-mail: cossu@post.kek.j [Scuola Normale Superiore and INFN, Pisa (Italy); D' Elia, M., E-mail: Massimo.Delia@ge.infn.i [Dipartimento di Fisica and INFN, Genova (Italy); Di Giacomo, A., E-mail: digiaco@df.unipi.i [Dipartimento di Fisica and INFN, Pisa (Italy)


    We perform a detailed study of the phase diagram of the lattice Higgs SU(2) model with fixed Higgs field length. Consistently with previsions based on the Fradkin-Shenker theorem we find a first order transition line with an endpoint whose position we determined. The diagram also shows cross-over lines: the cross-over corresponding to the pure SU(2) bulk is also present at nonzero coupling with the Higgs field and merges with the one that continues the line of first order transition beyond the critical endpoint. At high temperature the first order line becomes a crossover, whose position moves by varying the temperature.

  4. Study of cements silicate phases hydrated under high pressure and high temperature; Etude des phases silicatees du ciment hydrate sous haute pression et haute temperature

    Energy Technology Data Exchange (ETDEWEB)

    Meducin, F.


    This study concerns the durability of oil-well cementing. Indeed, in oil well cementing a cement slurry is pumped down the steel casing of the well up the annular space between it and the surrounding rock to support and protect the casing. The setting conditions of pressure and temperature may be very high (up to 1000 bar and 250 deg C at the bottom of the oil-well). In this research, the hydration of the main constituent of cement, synthetic tri-calcium silicate Ca{sub 3}SiO{sub 2}, often called C{sub 3}S (C = CaO; S = SiO{sub 2} and H H{sub 2}O), is studied. Calcium Silicate hydrates are prepared in high-pressure cells to complete their phase diagram (P,T) and obtain the stability conditions for each species. Indeed, the phases formed in these conditions are unknown and the study consists in the hydration of C{sub 3}S at different temperatures, pressures, and during different times to simulate the oil-well conditions. In a first step (until 120 deg C at ambient pressure) the C-S-H, a not well crystallized and non-stoichiometric phase, is synthesized: it brings adhesion and mechanical properties., Then, when pressure and temperature increase, crystallized phases appear such as jaffeite (Ca{sub 6}(Si{sub 2}O{sub 7})(OH){sub 6}) and hillebrandite (Ca{sub 2}(SiO{sub 3})(OH){sub 2}). Silicon {sup 29}Si Nuclear Magnetic Resonance (using standard sequences MAS, CPMAS) allow us to identify all the silicates hydrates formed. Indeed, {sup 29}Si NMR is a valuable tool to determine the structure of crystallized or not-well crystallized phases of cement. The characterization of the hydrated samples is completed by other techniques: X- Ray Diffraction and Scanning Electron Microscopy. The following results are found: jaffeite is the most stable phase at C/S=3. To simulate the hydration of real cement, hydration of C{sub 3}S with ground quartz and with or without super-plasticizers is done. In those cases, new phases appear: kilchoanite mainly, and xonotlite. A large amount of

  5. Mapping Isobaric Aging onto the Equilibrium Phase Diagram. (United States)

    Niss, Kristine


    The linear volume relaxation and the nonlinear volume aging of a glass-forming liquid are measured, directly compared, and used to extract the out-of-equilibrium relaxation time. This opens a window to investigate how the relaxation time depends on temperature, structure, and volume in parts of phase space that are not accessed by the equilibrium liquid. It is found that the temperature dependence of relaxation time is non-Arrhenius even in the isostructural case-challenging the Adam-Gibbs entropy model. Based on the presented data and the idea that aging happens through quasiequilibrium states, we suggest a mapping of the out-of-equilibrium states during isobaric aging to the equilibrium phase diagram. This mapping implies the existence of isostructural lines in the equilibrium phase diagram. The relaxation time is found to depend on the bath temperature, density, and a just single structural parameter, referred to as an effective temperature.

  6. Magnetic phase diagram of HoxTm1-x alloys

    DEFF Research Database (Denmark)

    Sarthour, R.S.; Cowley, R.A.; Ward, R.C.C.


    The magnetic phase diagram of the competing anisotropy system, Ho/Tm, has been determined by neutron-scattering techniques and the results compared with calculations based on a mean-field model. The crystal-field interactions in Ho favor alignment of the magnetic moments in the basal plane whereas......, with long-range order, were identified and the magnetic phase diagram, including a pentacritical point, determined. A mean-field model was used to explain the results and the results are in good agreement with the experimental results....... in Tm they favor alignment along the c axis. Single-crystal alloys were grown with molecular-beam epitaxy techniques in Oxford. The components of the magnetic moment alone the c direction and in the basal plane were determined from the neutron-scattering measurements. Five distinct magnetic phases...

  7. Phase diagram of a reentrant gel of patchy particles

    Energy Technology Data Exchange (ETDEWEB)

    Roldán-Vargas, Sándalo; Smallenburg, Frank; Sciortino, Francesco [Department of Physics, Sapienza, Università di Roma, Piazzale Aldo Moro 2, I-00185 Roma (Italy); Kob, Walter [Laboratoire Charles Coulomb, UMR 5221, CNRS and Université Montpellier 2, 34095 Montpellier (France)


    We study the phase diagram of a binary mixture of patchy particles which has been designed to form a reversible gel. For this we perform Monte Carlo and molecular dynamics simulations to investigate the thermodynamics of such a system and compare our numerical results with predictions based on the analytical parameter-free Wertheim theory. We explore a wide range of the temperature-density-composition space that defines the three-dimensional phase diagram of the system. As a result, we delimit the region of thermodynamic stability of the fluid. We find that for a large region of the phase diagram the Wertheim theory is able to give a quantitative description of the system. For higher densities, our simulations show that the system is crystallizing into a BCC structure. Finally, we study the relaxation dynamics of the system by means of the density and temperature dependences of the diffusion coefficient. We show that there exists a density range where the system passes reversibly from a gel to a fluid upon both heating and cooling, encountering neither demixing nor phase separation.

  8. Confinement in Polyakov gauge and the QCD phase diagram

    Energy Technology Data Exchange (ETDEWEB)

    Marhauser, Marc Florian


    We investigate Quantum Chromodynamics (QCD) in the framework of the functional renormalisation group (fRG). Thereby describing the phase transition from the phase with confined quarks into the quark-gluon-plasma phase. We focus on a physical gauge in which the mechanism driving the phase transition is discernible. We find results compatible with lattice QCD data, as well as with functional methods applied in different gauges. The phase transition is of the expected order and we computed critical exponents. Extensions of the model are discussed. When investigating the QCD phase diagram, we compute the effects of dynamical quarks at finite density on the running of the gauge coupling. Additionally, we calculate how these affect the deconfinement phase transition, also, dynamical quarks allow for the inclusion of a finite chemical potential. Concluding the investigation of the phase diagram, we establish a relation between confinement and chiral symmetry breaking, which is tied to the dynamical generation of hadron masses. In the investigations, we often encounter scale dependent fields. We investigate a footing on which these can be dealt with in a uniform way. (orig.)

  9. Cu–Ni nanoalloy phase diagram – Prediction and experiment


    Sopoušek Jiří; Vřešťál Jan; Pinkas Jiří; Brož Pavel; Buršík Jiří; Stýskalík Aleš; Škoda David; Zobač Ondřej; Lee Joonho


    The Cu-Ni nanoalloy phase diagram respecting the nanoparticle size as an extra variable was calculated by the CALPHAD method. The samples of the Cu-Ni nanoalloys were prepared by the solvothermal synthesis from metal precursors. The samples were characterized by means of dynamic light scattering (DLS), infrared spectroscopy (IR), inductively coupled plasma optical emission spectroscopy (ICP/OES), transmission electron microscopy (TEM, HRTEM), and differential scanning calorimetry (DSC). The n...

  10. Phase diagrams and lipid domains in multicomponent lipid bilayer mixtures. (United States)

    Feigenson, Gerald W


    Understanding the phase behavior of biological membranes is helped by the study of more simple systems. Model membranes that have as few as 3 components exhibit complex phase behavior that can be well described, providing insight for biological membranes. A number of different studies are in agreement on general findings for some compositional phase diagrams, in particular, those that model the outer leaflet of animal cell plasma membranes. These model mixtures include cholesterol, together with one high-melting lipid and one low-melting lipid. An interesting finding is of two categories of such 3-component mixtures, leading to what we term Type I and Type II compositional phase diagrams. The latter have phase regions of macroscopic coexisting domains of [Lalpha+Lbeta+Lo] and of [Lalpha+Lo], with domains resolved under the light microscope. Type I mixtures have the same phase coexistence regions, but the domains seem to be nanoscopic. Type I mixtures are likely to be better models for biological membranes.

  11. Quarks and gluons in the phase diagram of quantum chromodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Welzbacher, Christian Andreas


    In this dissertation we study the phase diagram of strongly interacting matter by approaching the theory of quantum chromodynamics in the functional approach of Dyson-Schwinger equations. With these quantum (field) equations of motions we calculate the non-perturbative quark propagator within the Matsubara formalism. We built up on previous works and extend the so-called truncation scheme, which is necessary to render the infinite tower of Dyson-Schwinger equations finite and study phase transitions of chiral symmetry and the confinement/deconfinement transition. In the first part of this thesis we discuss general aspects of quantum chromodynamics and introduce the Dyson-Schwinger equations in general and present the quark Dyson-Schwinger equation together with its counterpart for the gluon. The Bethe-Salpeter equation is introduced which is necessary to perform two-body bound state calculations. A view on the phase diagram of quantum chromodynamics is given, including the discussion of order parameter for chiral symmetry and confinement. Here we also discuss the dependence of the phase structure on the masses of the quarks. In the following we present the truncation and our results for an unquenched N{sub f} = 2+1 calculation and compare it to previous studies. We highlight some complementary details for the quark and gluon propagator and discus the resulting phase diagram, which is in agreement with previous work. Results for an equivalent of the Columbia plot and the critical surface are discussed. A systematically improved truncation, where the charm quark as a dynamical quark flavour is added, will be presented in Ch. 4. An important aspect in this investigation is the proper adjustment of the scales. This is done by matching vacuum properties of the relevant pseudoscalar mesons separately for N{sub f} = 2+1 and N f = 2+1+1 via a solution of the Bethe-Salpeter equation. A comparison of the resulting N{sub f} = 2+1 and N{sub f} = 2+1+1 phase diagram indicates

  12. Phase diagram and entanglement of two interacting topological Kitaev chains (United States)

    Herviou, Loïc; Mora, Christophe; Le Hur, Karyn


    A superconducting wire described by a p -wave pairing and a Kitaev Hamiltonian exhibits Majorana fermions at its edges and is topologically protected by symmetry. We consider two Kitaev wires (chains) coupled by a Coulomb-type interaction and study the complete phase diagram using analytical and numerical techniques. A topological superconducting phase with four Majorana fermions occurs until moderate interactions between chains. For large interactions, both repulsive and attractive, by analogy with the Hubbard model, we identify Mott phases with Ising-type magnetic order. For repulsive interactions, the Ising antiferromagnetic order favors the occurrence of orbital currents spontaneously breaking time-reversal symmetry. By strongly varying the chemical potentials of the two chains, quantum phase transitions towards fully polarized (empty or full) fermionic chains occur. In the Kitaev model, the quantum critical point separating the topological superconducting phase and the polarized phase belongs to the universality class of the critical Ising model in two dimensions. When increasing the Coulomb interaction between chains, then we identify an additional phase corresponding to two critical Ising theories (or two chains of Majorana fermions). We confirm the existence of such a phase from exact mappings and from the concept of bipartite fluctuations. We show the existence of negative logarithmic corrections in the bipartite fluctuations, as a reminiscence of the quantum critical point in the Kitaev model. Other entanglement probes such as bipartite entropy and entanglement spectrum are also used to characterize the phase diagram. The limit of large interactions can be reached in an equivalent setup of ultracold atoms and Josephson junctions.

  13. Phase diagrams and heterogeneous equilibria a practical introduction

    CERN Document Server

    Predel, Bruno; Pool, Monte


    This graduate-level textbook provides an introduction to the practical application of phase diagrams. It is intended for students and researchers in chemistry, metallurgy, mineralogy, and materials science as well as in engineering and physics. Heterogeneous equilibria are described by a minimum of theory illustrated by practical examples and realistic case discussions from the different fields of application. The treatment of the physical and energetic background of phase equilibria leads to the discussion of the thermodynamics of mixtures and the correlation between energetics and composition. Thus, tools for the prediction of energetic, structural, and physical quantities are provided. The authors treat the nucleation of phase transitions, the production and stability of technologically important metastable phases, and metallic glasses. Furthermore, the text also concisely presents the thermodynamics and composition of polymer systems.

  14. Moving through three-dimensional phase diagrams of monoclonal antibodies. (United States)

    Rakel, Natalie; Baum, Miriam; Hubbuch, Jürgen


    Protein phase behavior characterization is a multivariate problem due to the high amount of influencing parameters and the diversity of the proteins. Single influences on the protein are not understood and fundamental knowledge remains to be obtained. For this purpose, a systematic screening method was developed to characterize the influence of fluid phase conditions on the phase behavior of proteins in three-dimensional phase diagrams. This approach was applied to three monoclonal antibodies to investigate influences of pH, protein and salt concentrations, with five different salts being tested. Although differences exist between the antibodies, this extensive study confirmed the general applicability of the Hofmeister series over the broad parameter range analyzed. The influence of the different salts on the aggregation (crystallization and precipitation) probability was described qualitatively using this Hofmeister series, with a differentiation between crystallization and precipitation being impossible, however. © 2014 American Institute of Chemical Engineers.

  15. Intrinsic Ferroelastic Nanoscale Structure and Ideal Phase Diagrams of HTSC (United States)

    Phillips, J. C.


    HTSC occurs in oxide (not halide) perovskite and pseudoperovskite materials known for strong internal ferroelastic stresses. These stresses are relieved by domain formation, leaving residual giant Electron-Phonon (E-P) interactions. (This possibility led Bednorz and Mueller to discover HTSC.) Many experiments, reviewed by Jung, show domain formation in the HTSC cuprates (also CMR manganites) with domain diameters 3 nm. The popular parabolic generic phase diagram for HTSC is incomplete and misleading. It is based on LSxCO, where the Srx dopants have low mobility compared to Ox mobility in other HTSC; samples are not fully equilibrated even after annealing for months at high T. Nearly ideal phase diagrams occur in YBCO and Hg cuprate. With increasing x, Tc is at first insulating and then an Intermediate Phase (IP) appears continuously where Tc is represented by one or more plateaus. XAFS (Haskell, Stern) shows that local Orthorhombic Order (OO) exists, but is different from, non-zero macroscopic OO only for 0.15 related to ideal HTSC phase diagrams by a THREE-dimensional topological model that also explains atomic-level anomalies in neutron and infrared spectra, as well as pseudogaps. The platform is very broad: it also supports IPs in (1) semiconductor impurity bands, with E-dopant P interactions 25x normal E-P interactions, near the metal-insulator transition, and (2) in network glasses near the stiffness transition (Thorpe), where (NEW) the glass transition in the IP is nearly reversible (Boolchand). The model gives correct scaling exponents where observed.

  16. [Terminal phase hydration, pain and delirium

    DEFF Research Database (Denmark)

    Heick, A.


    Hydration of the terminal patient may relieve confusion and complaints of "dry mouth". But it may worsen oedema of the brain, lungs, and extremities, worsen terminal rattling and cause a need for frequent changing of diapers. The decision of whether and how to treat a dying patient with fluids sh...

  17. The intrinsic electronic phase diagram of iron-pnictide superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Hess, C.; Kondrat, A.; Narduzzo, A.; Hamann-Borrero, J.E.; Klingeler, R.; Grafe, H.; Lang, G.; Hammerath, F.; Paar, D.; Alfonsov, A.; Kataev, V.; Werner, J.; Behr, G.; Buechner, B. [Leibniz-Institute for Solid State and Materials Research, IFW Dresden, 01171 Dresden (Germany)


    We present a detailed study of the intrinsic electronic phase diagram of the oxypnictide superconductors in the normal state based on the analysis of the electrical resistivity {rho} of both LaO{sub 1-x}F{sub x}FeAs and SmO{sub 1-x}F{sub x}FeAs for a wide range of doping. Our data give clear-cut evidence for unusual normal state properties in these new materials. As a function of doping {rho} of LaO{sub 1-x}F{sub x}FeAs shows a clear transition from pseudogap to Fermi liquid-like behavior, mimicking the phase diagram of the cuprates. Moreover, our data reveal a correlation between the strength of the pseudogap signatures and the stability of the superconducting phase. The pseudogap signatures, which are clearly connected with the structural and magnetic transitions of the parent material, become stronger in SmO{sub 1-x}F{sub x}FeAs where superconductivity is enhanced and vanish when superconductivity is reduced in the doping region with Fermi liquid-like behavior. We further present evidence for the connection between the pseudogap signatures in electrical transport and the slowing-down of spin fluctuation.

  18. Phase diagram of a lattice of pancake vortex molecules

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Y., E-mail: y.tanaka@aist.go.j [National Institute of Advanced Industrial Science and Technology, Tsukuba (Japan); Crisan, A. [University of Birmingham, Birmingham (United Kingdom); National Institute of Materials Physics, Bucharest (Romania); Shivagan, D.D.; Iyo, A.; Shirage, P.M. [National Institute of Advanced Industrial Science and Technology, Tsukuba (Japan); Tokiwa, K.; Watanabe, T. [Tokyo University of Science, Noda (Japan); Terada, N. [Kagoshima University, Kagoshima (Japan)


    On a superconducting bi-layer with thickness much smaller than the penetration depth, lambda, a vortex molecule might form. A vortex molecule is composed of two fractional vortices and a soliton wall. The soliton wall can be regarded as a Josephson vortex missing magnetic flux (degenerate Josephson vortex) due to an incomplete shielding. The magnetic energy carried by fractional vortices is less than in the conventional vortex. This energy gain can pay a cost to form a degenerate Josephson vortex. The phase diagram of the vortex molecule is rich because of its rotational freedom.

  19. Phase Diagram of the Two-Chain Hubbard Model (United States)

    Park, Youngho; Liang, Shoudan; Lee, T. K.


    We have calculated the charge gap and spin gap for the two-chain Hubbard model as a function of the on-site Coulomb interaction and the interchain hopping amplitude. We used the density matrix renormalization group method and developed a method to calculate separately the gaps numerically for the symmetric and antisymmetric modes with respect to the exchange of the chain indices. We have found very different behaviors for the weak and strong interaction cases. Our calculated phase diagram is compared to the one obtained by Balents and Fisher using the weak coupling renormalization group technique.

  20. Magnetic phase diagrams from non-collinear canonical band theory

    DEFF Research Database (Denmark)

    Shallcross, Sam; Nordstrom, L.; Sharma, S.


    A canonical band theory of non-collinear magnetism is developed and applied to the close packed fcc and bcc crystal structures. This is a parameter-free theory where the crystal and magnetic symmetry and exchange splitting uniquely determine the electronic bands. In this way, we are able...... to construct phase diagrams of magnetic order for the fcc and bcc lattices. Several examples of non-collinear magnetism are seen to be canonical in origin, in particular, that of gamma-Fe. In this approach, the determination of magnetic stability results solely from changes in kinetic energy due to spin...

  1. Phase diagram of polar states in doped ferroelectric systems (United States)

    Wang, Dong; Ke, Xiaoqin; Wang, Yunzhi; Gao, Jinghui; Wang, Yu; Zhang, Lixue; Yang, Sen; Ren, Xiaobing


    We report a complete phase diagram that describes the relationships among all polar states in doped ferroelectrics, including the paraelectric (polar liquid), ferroelectric (polar crystal), relaxor (polar glass), and precursory states (partially frozen nanopolar domains). We employ a model that considers a randomly distributed local polarization field associated with point defects, which breaks the symmetry of the Landau free energy with respect to polarization. In the meantime, the model also takes into account the effect of point defects on the overall stability of the ferroelectric phase. Based on this model, the phase field simulations reproduce all the polar states and important characteristics associated with ferroelectric-glass (relaxor) transition observed in experiments, including rugged free energy, wide relaxation time, nanosized ferroelectric domain structure, “diffuse” transition, temperature dependence of third-order dielectric susceptibility, nonergodicity, frequency dependence of dielectric loss, and domain switching.

  2. Magnetic phase diagram of graphene nanorings in an electric field. (United States)

    Zhou, Aiping; Sheng, Weidong


    Magnetic properties of graphene nanorings are investigated in the presence of an electric field. Within the formalism of Hubbard model, the graphene nanorings of various geometric configurations are found to exhibit rich phase diagram. For a nanoring system which has degenerate states at the Fermi level, the system is shown to undergo an abrupt phase transition from the antiferromagnetic to a nonmagnetic state in an electric field applied cross its zigzag edges. However, the nanoring is found to always stay in the antiferromagnetic state when the electric field is applied cross its armchair edges. For the other nanoring system with a finite single-particle gap, the magnetic moments of its antiferromagnetic ground state is seen to decrease gradually to zero with the electric field applied cross the zigzag edges. When the electric field is applied cross the armchair edges, the nanoring is shown to undergo several magnetic phase transitions before settling itself in a nonmagnetic ordering.

  3. Phase diagrams of ferroelectric nanocrystals strained by an elastic matrix. (United States)

    Nikitchenko, Andrei; Azovtsev, Andrei V; Pertsev, Nikolay A


    Ferroelectric crystallites embedded into a dielectric matrix experience temperature-dependent elastic strains caused by differences in the thermal expansion of the crystallites and the matrix. Owing to the electrostriction, these lattice strains may affect polarization states of ferroelectric inclusions significantly, making them different from those of a stress-free bulk crystal. Here, using a nonlinear thermodynamic theory, we study the mechanical effect of elastic matrix on the phase states of embedded single-domain ferroelectric nanocrystals. Their equilibrium polarization states are determined by minimizing a special thermodynamic potential that describes the energetics of an ellipsoidal ferroelectric inclusion surrounded by a linear elastic medium. To demonstrate stability ranges of such states for a given material combination, we introduce an original phase diagram, where the inclusion's shape anisotropy and temperature are used as two parameters. The "shape-temperature" phase diagrams are calculated numerically for PbTiO3 and BaTiO3 nanocrystals embedded into representative dielectric matrices generating tensile (silica glass) or compressive (potassium silicate glass) thermal stresses inside ferroelectric inclusions. The developed phase maps demonstrate that the joint effect of thermal stresses and matrix-induced elastic clamping of ferroelectric inclusions gives rise to several important features in the polarization behavior of PbTiO3 and BaTiO3 nanocrystals. In particular, the Curie temperature displays a nonmonotonic variation with the ellipsoid's aspect ratio, being minimal for spherical inclusions. Furthermore, the diagrams show that the polarization orientation with respect to the ellipsoid's symmetry axis is controlled by the shape anisotropy and the sign of thermal stresses. Under certain conditions, the mechanical inclusion-matrix interaction qualitatively alters the evolution of ferroelectric states on cooling, inducing a structural transition in

  4. Aggregation of flexible polyelectrolytes: Phase diagram and dynamics (United States)

    Tom, Anvy Moly; Rajesh, R.; Vemparala, Satyavani


    Similarly charged polymers in solution, known as polyelectrolytes, are known to form aggregated structures in the presence of oppositely charged counterions. Understanding the dependence of the equilibrium phases and the dynamics of the process of aggregation on parameters such as backbone flexibility and charge density of such polymers is crucial for insights into various biological processes which involve biological polyelectrolytes such as protein, DNA, etc. Here, we use large-scale coarse-grained molecular dynamics simulations to obtain the phase diagram of the aggregated structures of flexible charged polymers and characterize the morphology of the aggregates as well as the aggregation dynamics, in the presence of trivalent counterions. Three different phases are observed depending on the charge density: no aggregation, a finite bundle phase where multiple small aggregates coexist with a large aggregate and a fully phase separated phase. We show that the flexibility of the polymer backbone causes strong entanglement between charged polymers leading to additional time scales in the aggregation process. Such slowing down of the aggregation dynamics results in the exponent, characterizing the power law decay of the number of aggregates with time, to be dependent on the charge density of the polymers. These results are contrary to those obtained for rigid polyelectrolytes, emphasizing the role of backbone flexibility.

  5. Navigating at Will on the Water Phase Diagram (United States)

    Pipolo, S.; Salanne, M.; Ferlat, G.; Klotz, S.; Saitta, A. M.; Pietrucci, F.


    Despite the simplicity of its molecular unit, water is a challenging system because of its uniquely rich polymorphism and predicted but yet unconfirmed features. Introducing a novel space of generalized coordinates that capture changes in the topology of the interatomic network, we are able to systematically track transitions among liquid, amorphous, and crystalline forms throughout the whole phase diagram of water, including the nucleation of crystals above and below the melting point. Our approach, based on molecular dynamics and enhanced sampling or free energy calculation techniques, is not specific to water and could be applied to very different structural phase transitions, paving the way towards the prediction of kinetic routes connecting polymorphic structures in a range of materials.

  6. Phase diagram for ortho-para-hydrogen monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, N S [Physics Department, University of Florida, PO Box 118400, Gainesville, FL 32611-8400 (United States); Kokshenev, V B [Departamento de FIsica, Universidade Federal de Minas Gerais, Caixa Postal 702, 30123-970, Belo Horizonte, Minas Gerais (Brazil)


    The phase diagram for orientational ordering of hydrogen monolayers on graphite and boron nitride is revised in view of current theory and experimental observations from nuclear magnetic resonance (NMR) studies recently reported for ortho-H{sub 2} concentrations 0.35 {<=} c {<=} 0.92 and temperatures 0.14 {<=} T {<=} 1.80 K. The characteristic interaction coupling {gamma}{sub 0} = 0.50 {+-} 0.03 K and the crystalline field amplitude V{sub 0} = 0.70 {+-} 0.10 K are derived from experimental data, and distinct types of the local orientationally ordered structures are analysed using a proposed model for site-diluted uniaxial quadrupoles on a triangular plane lattice of hexagonal symmetry. The long-range periodic pinwheel structure and the short-range quadrupolar glass (QG) phase are stable above the 2D site-percolation limit, c{sub p} = 0.72, and for 0.48 < c < c{sub p}, respectively, where quadrupolar-order effects dominate. At very low T, the QG phase shows instability with respect to local dipole-like polarization effects and the ground state changes to a hindered rotor state. Two para-rotational local ordered PRA and PRB structures driven, respectively, by positive and negative crystalline fields are well distinguished, experimentally and theoretically, and are rather different from the unique PR phase suggested earlier by Harris and Berlinsky.

  7. Liquid-ordered phases induced by cholesterol: a compendium of binary phase diagrams. (United States)

    Marsh, Derek


    Mixtures of phospholipids with cholesterol are able to form liquid-ordered phases that are characterised by short-range orientational order and long-range translational disorder. These L(o)-phases are distinct from the liquid-disordered, fluid L(alpha)-phases and the solid-ordered, gel L(beta)-phases that are assumed by the phospholipids alone. The liquid-ordered phase can produce spatially separated in-plane fluid domains, which, in the form of lipid rafts, are thought to act as platforms for signalling and membrane sorting in cells. The areas of domain formation are defined by the regions of phase coexistence in the phase diagrams for the binary mixtures of lipid with cholesterol. In this paper, the available binary phase diagrams of lipid-cholesterol mixtures are all collected together. It is found that there is not complete agreement between different determinations of the phase diagrams for the same binary mixture. This can be attributed to the indirect methods largely used to establish the phase boundaries. Intercomparison of the various data sets allows critical assessment of which phase boundaries are rigorously established from direct evidence for phase coexistence. Copyright 2010 Elsevier B.V. All rights reserved.

  8. Universal phase diagrams with superconducting domes for electronic flat bands (United States)

    Löthman, Tomas; Black-Schaffer, Annica M.


    Condensed matter systems with flat bands close to the Fermi level generally exhibit, due to their very large density of states, extraordinarily high critical ordering temperatures of symmetry-breaking orders, such as superconductivity and magnetism. Here we show that the critical temperatures follow one of two universal curves with doping away from a flat band depending on the ordering channel, which completely dictates both the general order competition and the phase diagram. Notably, we find that orders in the particle-particle channel (superconducting orders) survive decisively farther than orders in the particle-hole channel (magnetic or charge orders) because the channels have fundamentally different polarizabilities. Thus, even if a magnetic or charge order initially dominates, superconducting domes are still likely to exist on the flanks of flat bands. We apply these general results to both the topological surface flat bands of rhombohedral ABC-stacked graphite and to the Van Hove singularity of graphene.

  9. "Property Phase Diagrams" for Compound Semiconductors through Data Mining. (United States)

    Srinivasan, Srikant; Rajan, Krishna


    This paper highlights the capability of materials informatics to recreate "property phase diagrams" from an elemental level using electronic and crystal structure properties. A judicious selection of existing data mining techniques, such as Principal Component Analysis, Partial Least Squares Regression, and Correlated Function Expansion, are linked synergistically to predict bandgap and lattice parameters for different stoichiometries of GaxIn1-xAsySb1-y, starting from fundamental elemental descriptors. In particular, five such elemental descriptors, extracted from within a database of highly correlated descriptors, are shown to collectively capture the widely studied "bowing" of energy bandgaps seen in compound semiconductors. This is the first such demonstration, to our knowledge, of establishing relationship between discrete elemental descriptors and bandgap bowing, whose underpinning lies in the fundamentals of solid solution thermodyanamics.

  10. Phase Diagram and Electronic Structure of Praseodymium and Plutonium

    Directory of Open Access Journals (Sweden)

    Nicola Lanatà


    Full Text Available We develop a new implementation of the Gutzwiller approximation in combination with the local density approximation, which enables us to study complex 4f and 5f systems beyond the reach of previous approaches. We calculate from first principles the zero-temperature phase diagram and electronic structure of Pr and Pu, finding good agreement with the experiments. Our study of Pr indicates that its pressure-induced volume-collapse transition would not occur without change of lattice structure—contrarily to Ce. Our study of Pu shows that the most important effect originating the differentiation between the equilibrium densities of its allotropes is the competition between the Peierls effect and the Madelung interaction and not the dependence of the electron correlations on the lattice structure.

  11. Modelling of phase diagrams of nanoalloys with complex metallic phases: application to Ni-Sn. (United States)

    Kroupa, A; Káňa, T; Buršík, J; Zemanová, A; Šob, M


    A method for modelling of size-dependent phase diagrams was developed by combining the semiempirical CALPHAD method and ab initio calculations of surface stresses for intermetallic phases. A novel approach was devised for the calculation of surface energy, free of systematic errors from the selection of different parameters of the software (e.g. number of the k-points) and for handling layered structures and off-stoichiometric slabs. Our approach allows the determination of complex size-dependent phase diagrams of systems with intermetallic phases, which was not possible up to now. The method was verified for the modelling of the phase diagram of the Ni-Sn system and basic comparison with rare experimental results was shown. There is reasonable agreement between the calculated and experimental results. The modelling of size-dependent phase diagrams of real systems allows the prediction of phase equilibria existing in nanosystems and possible changes in material properties. There is a need for such knowledge and the existence of reliable data for simpler systems is crucial for further application of this approach. This should motivate future experimental work.

  12. Phase diagrams of exceptional and supersymmetric lattice gauge theories

    Energy Technology Data Exchange (ETDEWEB)

    Wellegehausen, Bjoern-Hendrik


    In this work different strongly-coupled gauge theories with and without fundamental matter have been studied on the lattice with an emphasis on the confinement problem and the QCD phase diagram at nonvanishing net baryon density as well as on possible supersymmetric extensions of the standard model of particle physics. In gauge theories with a non-trivial centre symmetry, as for instance SU(3)-Yang-Mills theory, confinement is intimately related to the centre of the gauge group, and the Polyakov loop serves as an order parameter for confinement. In QCD, this centre symmetry is explicitly broken by quarks in the fundamental representation of the gauge group. But still quarks and gluons are confined in mesons, baryons and glueballs at low temperatures and small densities, suggesting that centre symmetry is not responsible for the phenomenon of confinement. Therefore it is interesting to study pure gauge theories without centre symmetry. In this work this has been done by replacing the gauge group SU(3) of the strong interaction with the exceptional Lie group G{sub 2}, that has a trivial centre. To investigate G{sub 2} gauge theory on the lattice, a new and highly efficient update algorithm has been developed, based on a local HMC algorithm. Employing this algorithm, the proposed and already investigated first order phase transition from a confined to a deconfined phase has been confirmed, showing that indeed a first order phase transition without symmetry breaking or an order parameter is possible. In this context, also the deconfinement phase transition of the exceptional Lie groups F4 and E6 in three spacetime dimensions has been studied. It has been shown that both theories also possess a first order phase transition.

  13. Phase diagram for ortho-para-hydrogen monolayers

    CERN Document Server

    Sullivan, N S


    The phase diagram for orientational ordering of hydrogen monolayers on graphite and boron nitride is revised in view of current theory and experimental observations from nuclear magnetic resonance (NMR) studies recently reported for ortho-H sub 2 concentrations 0.35 <= c <= 0.92 and temperatures 0.14 <= T <= 1.80 K. The characteristic interaction coupling GAMMA sub 0 = 0.50 +- 0.03 K and the crystalline field amplitude V sub 0 = 0.70 +- 0.10 K are derived from experimental data, and distinct types of the local orientationally ordered structures are analysed using a proposed model for site-diluted uniaxial quadrupoles on a triangular plane lattice of hexagonal symmetry. The long-range periodic pinwheel structure and the short-range quadrupolar glass (QG) phase are stable above the 2D site-percolation limit, c sub p = 0.72, and for 0.48 < c < c sub p , respectively, where quadrupolar-order effects dominate. At very low T, the QG phase shows instability with respect to local dipole-like polariz...

  14. Hydrate Phase Assemblages in Calcium Sulfoaluminate - Metakaolin - Limestone Blends

    DEFF Research Database (Denmark)

    Pedersen, Malene Thostrup; Lothenbach, Barbara; Winnefeld, Frank


    as 27Al and 29Si NMR and compared with predictions from thermodynamic modelling. The results show almost full degrees of reaction for ye’elimite in all blends and that the degrees of reaction for belite and MK have an important impact on the hydrate phases and their quantities formed in the ternary...... systems....

  15. Matrix model approximations of fuzzy scalar field theories and their phase diagrams

    Energy Technology Data Exchange (ETDEWEB)

    Tekel, Juraj [Department of Theoretical Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, Mlynska Dolina, Bratislava, 842 48 (Slovakia)


    We present an analysis of two different approximations to the scalar field theory on the fuzzy sphere, a nonperturbative and a perturbative one, which are both multitrace matrix models. We show that the former reproduces a phase diagram with correct features in a qualitative agreement with the previous numerical studies and that the latter gives a phase diagram with features not expected in the phase diagram of the field theory.

  16. Phase Diagram Characterization Using Magnetic Beads as Liquid Carriers. (United States)

    Blumenschein, Nicholas; Han, Daewoo; Steckl, Andrew J


    Magnetic beads with ~1.9 µm average diameter were used to transport microliter volumes of liquids between contiguous liquid segments with a tube for the purpose of investigating phase change of those liquid segments. The magnetic beads were externally controlled using a magnet, allowing for the beads to bridge the air valve between the adjacent liquid segments. A hydrophobic coating was applied to the inner surface of the tube to enhance the separation between two liquid segments. The applied magnetic field formed an aggregate cluster of magnetic beads, capturing a certain liquid amount within the cluster that is referred to as carry-over volume. A fluorescent dye was added to one liquid segment, followed by a series of liquid transfers, which then changed the fluorescence intensity in the neighboring liquid segment. Based on the numerical analysis of the measured fluorescence intensity change, the carry-over volume per mass of magnetic beads has been found to be ~2 to 3 µl/mg. This small amount of liquid allowed for the use of comparatively small liquid segments of a couple hundred microliters, enhancing the feasibility of the device for a lab-in-tube approach. This technique of applying small compositional variation in a liquid volume was applied to analyzing the binary phase diagram between water and the surfactant C12E5 (pentaethylene glycol monododecyl ether), leading to quicker analysis with smaller sample volumes than conventional methods.

  17. Energy spectrum and phase diagrams of two-sublattice hard-core boson model

    Directory of Open Access Journals (Sweden)

    I.V. Stasyuk


    Full Text Available The energy spectrum, spectral density and phase diagrams have been obtained for two-sublattice hard-core boson model in frames of random phase approximation approach. Reconstruction of boson spectrum at the change of temperature, chemical potential and energy difference between local positions in sublattices is studied. The phase diagrams illustrating the regions of existence of a normal phase which can be close to Mott-insulator (MI or charge-density (CDW phase diagrams as well as the phase with the Bose-Einstein condensate (SF phase are built.

  18. Inhomogeneous hard-core bosonic mixture with checkerboard supersolid phase: Quantum and thermal phase diagram (United States)

    Heydarinasab, F.; Abouie, J.


    We introduce an inhomogeneous bosonic mixture composed of two kinds of hard-core and semi-hard-core bosons with different nilpotency conditions and demonstrate that in contrast with the standard hard-core Bose-Hubbard model, our bosonic mixture with nearest- and next-nearest-neighbor interactions on a square lattice develops the checkerboard supersolid phase characterized by the simultaneous superfluid and checkerboard solid orders. Our bosonic mixture is created from a two-orbital Bose-Hubbard model including two kinds of bosons: a single-orbital boson and a two-orbital boson. By mapping the bosonic mixture to an anisotropic inhomogeneous spin model in the presence of a magnetic field, we study the ground-state phase diagram of the model by means of cluster mean field theory and linear spin-wave theory and show that various phases such as solid, superfluid, supersolid, and Mott insulator appear in the phase diagram of the mixture. Competition between the interactions and magnetic field causes the mixture to undergo different kinds of first- and second-order phase transitions. By studying the behavior of the spin-wave excitations, we find the reasons of all first- and second-order phase transitions. We also obtain the temperature phase diagram of the system using cluster mean field theory. We show that the checkerboard supersolid phase persists at finite temperature comparable with the interaction energies of bosons.

  19. High-field phase-diagram of Fe arsenide superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Y.J.; Jaroszynski, J.; Yamamoto, A.; Gurevich, A.; Riggs, S.C.; Boebinger, G.S.; Larbalestier, D. [National High Magnetic Field Laboratory, Florida State University, Tallahassee-FL 32310 (United States); Wen, H.H. [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Zhigadlo, N.D.; Katrych, S.; Bukowski, Z.; Karpinski, J. [Laboratory for Solid State Physics, ETH Zuerich, CH-8093 Zuerich (Switzerland); Liu, R.H.; Chen, H.; Chen, X.H. [Hefei National Laboratory for Physical Science a Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Balicas, L., E-mail: balicas@magnet.fsu.ed [National High Magnetic Field Laboratory, Florida State University, Tallahassee-FL 32310 (United States)


    Here, we report an overview of the phase-diagram of single-layered and double-layered Fe arsenide superconductors at high magnetic fields. Our systematic magneto-transport measurements of polycrystalline SmFeAsO{sub 1-x}F{sub x} at different doping levels confirm the upward curvature of the upper critical magnetic field H{sub c2}(T) as a function of temperature T defining the phase boundary between the superconducting and metallic states for crystallites with the ab planes oriented nearly perpendicular to the magnetic field. We further show from measurements on single-crystals that this feature, which was interpreted in terms of the existence of two superconducting gaps, is ubiquitous among both series of single- and double-layered compounds. In all compounds explored by us the zero temperature upper critical field H{sub c2}(0), estimated either through the Ginzburg-Landau or the Werthamer-Helfand-Hohenberg single gap theories, strongly surpasses the weak-coupling Pauli paramagnetic limiting field. This clearly indicates the strong-coupling nature of the superconducting state and the importance of magnetic correlations for these materials. Our measurements indicate that the superconducting anisotropy, as estimated through the ratio of the effective masses gamma = (m{sub c}/m{sub ab}){sup 1/2} for carriers moving along the c-axis and the ab-planes, respectively, is relatively modest as compared to the high-T{sub c} cuprates, but it is temperature, field and even doping dependent. Finally, our preliminary estimations of the irreversibility field H{sub m}(T), separating the vortex-solid from the vortex-liquid phase in the single-layered compounds, indicates that it is well described by the melting of a vortex lattice in a moderately anisotropic uniaxial superconductor.

  20. Conformational properties of rigid-chain amphiphilic macromolecules : The phase diagram

    NARCIS (Netherlands)

    Markov, V. A.; Vasilevskaya, V. V.; Khalatur, P. G.; ten Brinke, G.; Khokhlov, A. R.

    The coil-globule transition in rigid-chain amphiphilic macromolecules was studied by means of computer simulation, and the phase diagrams for such molecules in the solvent quality-persistence length coordinates were constructed. It was shown that the type of phase diagram depends to a substantial

  1. Theoretical phase diagrams for [N(CD3)4]2ZnCl4 crystal (United States)

    Sannikov, D. G.


    A theoretical phase diagram of [N(CD3)4]2ZnCl4 crystal is constructed in the plane of two thermodynamic-potential coefficients. The orientation of the temperature ( T) and pressure ( P) axes is chosen in the diagram. The first diagram is used as a basis to construct the second theoretical T-P phase diagram, expanded to the region of weak negative pressures for nondeuterated [N(CH3)4]2ZnCl4 crystal. It is suggested that this region can be observed for deuterated [N(CD3)4]2ZnCl4 crystal.

  2. Prediction of phase equilibrium and hydration free energy of carboxylic acids by Monte Carlo simulations. (United States)

    Ferrando, Nicolas; Gedik, Ibrahim; Lachet, Véronique; Pigeon, Laurent; Lugo, Rafael


    In this work, a new transferable united-atom force field has been developed to predict phase equilibrium and hydration free energy of carboxylic acids. To take advantage of the transferability of the AUA4 force field, all Lennard-Jones parameters of groups involved in the carboxylic acid chemical function are reused from previous parametrizations of this force field. Only a unique set of partial electrostatic charges is proposed to reproduce the experimental gas phase dipole moment, saturated liquid densities and vapor pressures. Phase equilibrium properties of various pure carboxylic acids (acetic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoic acid) and one diacid (1,5-pentanedioic) are studied through Monte Carlo simulations in the Gibbs ensemble. A good accuracy is obtained for pure compound saturated liquid densities and vapor pressures (average deviation of 2% and 6%, respectively), as well as for critical points. The vaporization enthalpy is, however, poorly predicted for short acids, probably due to a limitation of the force field to correctly describe the significant dimerization in the vapor phase. Pressure-composition diagrams for two binary mixtures (acetic acid + n-butane and propanoic acid + pentanoic acid) are also computed with a good accuracy, showing the transferability of the proposed force field to mixtures. Hydration free energies are calculated for three carboxylic acids using thermodynamic integration. A systematic overestimation of around 10 kJ/mol is observed compared to experimental data. This new force field parametrized only on saturated equilibrium properties appears insufficient to reach an acceptable precision for this property, and only relative hydration free energies between two carboxylic acids can be correctly predicted. This highlights the limitation of the transferability feature of force fields to properties not included in the parametrization database.

  3. Phase diagram of a 4-component lipid mixture: DSPC/DOPC/POPC/chol. (United States)

    Konyakhina, Tatyana M; Wu, Jing; Mastroianni, James D; Heberle, Frederick A; Feigenson, Gerald W


    We report the first 4-component phase diagram for the lipid bilayer mixture, DSPC/DOPC/POPC/chol (distearoylphosphatidylcholine/dioleoylphosphatidylcholine/1-palmitoyl, 2-oleoylphosphatidylcholine/cholesterol). This phase diagram, which has macroscopic Ld+Lo phase domains, clearly shows that all phase boundaries determined for the 3-component mixture containing DOPC transition smoothly into the boundaries for the 3-component mixture containing POPC, which has nanoscopic phase domains of Ld+Lo. Our studies start from two published ternary phase diagrams, and show how these can be combined into a quaternary phase diagram by study of a few hundred samples of intermediate compositions. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Phase equilibra in binary Lennard-Jones mixtures: phase diagram simulation (United States)

    Canongia Lopes, J. N.

    A three-box version of the Gibbs ensemble Monte Carlo method was used to determine the phase diagram type of several binary mixtures of one-centre Lennard-Jones particles. The method can be used to establish a direct link between the intermolecular potential modelling the interactions in a given system and its fluid phase diagram, without the knowledge of the corresponding equation of state governing its pV T behaviour. As an example of the application of the method, closed-loop behaviour in an isotropic system could be found using a set of Lennard-Jones parameters exhibiting a cross-interaction diameter with a negative deviation from the Lorentz-Berthelot combination rule.

  5. Phase stability in nanoscale material systems: extension from bulk phase diagrams (United States)

    Bajaj, Saurabh; Haverty, Michael G.; Arróyave, Raymundo; Goddard Frsc, William A., III; Shankar, Sadasivan


    Phase diagrams of multi-component systems are critical for the development and engineering of material alloys for all technological applications. At nano dimensions, surfaces (and interfaces) play a significant role in changing equilibrium thermodynamics and phase stability. In this work, it is shown that these surfaces at small dimensions affect the relative equilibrium thermodynamics of the different phases. The CALPHAD approach for material surfaces (also termed ``nano-CALPHAD'') is employed to investigate these changes in three binary systems by calculating their phase diagrams at nano dimensions and comparing them with their bulk counterparts. The surface energy contribution, which is the dominant factor in causing these changes, is evaluated using the spherical particle approximation. It is first validated with the Au-Si system for which experimental data on phase stability of spherical nano-sized particles is available, and then extended to calculate phase diagrams of similarly sized particles of Ge-Si and Al-Cu. Additionally, the surface energies of the associated compounds are calculated using DFT, and integrated into the thermodynamic model of the respective binary systems. In this work we found changes in miscibilities, reaction compositions of about 5 at%, and solubility temperatures ranging from 100-200 K for particles of sizes 5 nm, indicating the importance of phase equilibrium analysis at nano dimensions.Phase diagrams of multi-component systems are critical for the development and engineering of material alloys for all technological applications. At nano dimensions, surfaces (and interfaces) play a significant role in changing equilibrium thermodynamics and phase stability. In this work, it is shown that these surfaces at small dimensions affect the relative equilibrium thermodynamics of the different phases. The CALPHAD approach for material surfaces (also termed ``nano-CALPHAD'') is employed to investigate these changes in three binary systems by

  6. Phase diagrams and physicochemical properties of Li+,K+(Rb+)//borate-H2O systems at 323 K (United States)

    Feng, Shan; Yu, Xudong; Cheng, Xinglong; Zeng, Ying


    The phase and physicochemical properties diagrams of Li+,K+(Rb+)//borate-H2O systems at 323 K were constructed using the experimentally measured solubilities, densities, and refractive indices. The Schreinemakers' wet residue method and the X-ray diffraction were used for the determination of the compositions of solid phase. Results show that these two systems belong to the hydrate I type, with no solid solution or double salt formation. The borate phases formed in our experiments are RbB5O6(OH)4 · 2H2O, Li2B4O5(OH)4 · H2O, and K2B4O5(OH)4 · 2H2O. Comparison between the stable phase diagrams of the studied system at 288, 323, and 348 K show that in this temperature range, the crystallization form of salts do not changed. With the increase in temperature, the crystallization field of Li2B4O5(OH)4 · H2O salt at 348 K is obviously larger than that at 288 K. In the Li+,K+(Rb+)//borate-H2O systems, the densities and refractive indices of the solutions (at equilibrium) increase along with the mass fraction of K2B4O7 (Rb2B4O7), and reach the maximum values at invariant point E.

  7. Ternary phase behaviour and vesicle formation of a sodium N-lauroylsarcosinate hydrate/1-decanol/water system (United States)

    Akter, Nasima; Radiman, Shahidan; Mohamed, Faizal; Rahman, Irman Abdul; Reza, Mohammad Imam Hasan


    The phase behaviour of a system composed of amino acid-based surfactant (sodium N-lauroylsarcosinate hydrate), 1-decanol and deionised water was investigated for vesicle formation. Changing the molar ratio of the amphiphiles, two important aggregate structures were observed in the aqueous corner of the phase diagram. Two different sizes of microemulsions were found at two amphiphile-water boundaries. A stable single vesicle lobe was found for 1∶2 molar ratios in 92 wt% water with vesicles approximately 100 nm in size and with high zeta potential value. Structural variation arises due to the reduction of electrostatic repulsions among the ionic headgroups of the surfactants and the hydration forces due to adsorbed water onto monolayer's. The balance of these two forces determines the aggregate structures. Analysis was followed by the molecular geometrical structure. These findings may have implications for the development of drug delivery systems for cancer treatments, as well as cosmetic and food formulations.

  8. The use of phase diagrams and thermodynamic databases for electronic materials (United States)

    Liu, X. J.; Kainuma, R.; Ohnuma, I.; Ishida, K.; Oikawa, K.


    Phase diagrams and a thermodynamic database constructed by the Calculation of Phase Diagrams approach offer powerful tools for alloy design and materials development. This article presents recent progress on the thermodynamic database for microsolders and copper-based alloys, which is useful for the development of lead-free solders and prediction of interfacial phenomena between solders and the copper substrate in electronic packaging technology. In addition, examples of phase diagram applications are presented to facilitate the development of Co-Cr-based magnetic recording media in hard disks and new ferromagnetic shape-memory alloys.

  9. Phase diagram of inverse patchy colloids assembling into an equilibrium laminar phase. (United States)

    Noya, Eva G; Kolovos, Ismene; Doppelbauer, Günther; Kahl, Gerhard; Bianchi, Emanuela


    We numerically study the phase behavior of colloidal particles with two charged patches at the poles and an oppositely charged equatorial belt. Interactions between particles are described using the inverse patchy colloid model, where the term inverse emphasizes the difference with respect to conventional patchy particles: as a consequence of the heterogeneous charge distribution, the patches on the particle surface repel each other, whereas the patches and non-patch regions mutually attract. For the model parameters considered in this work, the system exhibits an unusual equilibrium phase diagram characterized by a broad region where a novel structure composed of parallel colloidal monolayers is stable.

  10. The non-equilibrium phase diagrams of flow-induced crystallization and melting of polyethylene. (United States)

    Wang, Zhen; Ju, Jianzhu; Yang, Junsheng; Ma, Zhe; Liu, Dong; Cui, Kunpeng; Yang, Haoran; Chang, Jiarui; Huang, Ningdong; Li, Liangbin


    Combining extensional rheology with in-situ synchrotron ultrafast x-ray scattering, we studied flow-induced phase behaviors of polyethylene (PE) in a wide temperature range up to 240 °C. Non-equilibrium phase diagrams of crystallization and melting under flow conditions are constructed in stress-temperature space, composing of melt, non-crystalline δ, hexagonal and orthorhombic phases. The non-crystalline δ phase is demonstrated to be either a metastable transient pre-order for crystallization or a thermodynamically stable phase. Based on the non-equilibrium phase diagrams, nearly all observations in flow-induced crystallization (FIC) of PE can be well understood. The interplay of thermodynamic stabilities and kinetic competitions of the four phases creates rich kinetic pathways for FIC and diverse final structures. The non-equilibrium flow phase diagrams provide a detailed roadmap for precisely processing of PE with designed structures and properties.

  11. Binary Solid-Liquid Phase Diagram of Phenol and t-Butanol: An Undergraduate Physical Chemistry Experiment (United States)

    Xu, Xinhua; Wang, Xiaogang; Wu, Meifen


    The determination of the solid-liquid phase diagram of a binary system is always used as an experiment in the undergraduate physical chemistry laboratory courses. However, most phase diagrams investigated in the lab are simple eutectic ones, despite the fact that complex binary solid-liquid phase diagrams are more common. In this article, the…

  12. The effect of hydration stress solutes on the phase behavior of hydrated dipalmitoylphosphatidylcholine. (United States)

    Rudolph, A S; Goins, B


    We have investigated the interaction of solutes found to accumulate in biological systems during chilling, dehydration, and salt stress with fully hydrated multilamellar and unilamellar vesicles of dipalmitoylphosphatidylcholine (DPPC). We have focused on a series of mono-, di-, and tri-substituted amines (glycine, 4-hydroxyproline, proline, and betaine) and contrasted the action of these solutes to trehalose, a protective disaccharide. Differential scanning calorimetry studies show that when DPPC is scanned in the presence of increasing concentrations of these solutes (up to 3 M), there is a moderate increase in the pre-transition temperature (1-6 degrees C) with a smaller increase (1-2 degrees C) in the main transition temperature of hydrated multilamellar vesicles of DPPC. Other calorimetric parameters (delta H, delta T1/2, Cpmax) determined for the pre-transition and main transition were similar independent of the solute. In each case, the main phase transition was broadened with increasing solute while the transition enthalpy was not significantly affected.

  13. Phase diagram for one-way traffic flow with local control (United States)

    Lykov, A. A.; Malyshev, V. A.; Melikian, M. V.


    We consider one-way road deterministic traffic model with N particles. The simplest local control protocol, which reminds physical interaction is considered. We obtain complete phase diagram uniformly in N and study in detail its stable and unstable domains.


    Directory of Open Access Journals (Sweden)

    Alexei Baerle


    Full Text Available Phase state and the charge of colloidal particles in the gelatine-polyuronate system were studied. A method for comparative evaluation of molecular weight of colloids by means of viscosimetric measurements and electrophoresis was developed. It is shown that the Diagram {Phase state = f (composition, pH} contains six well-defined regions. The diagram explains and predicts the behaviour of protein-polysaccharide colloids, which are included in beverages or forms the shells of oil-containing microcapsules.

  15. Calculation of Liquid Water-Hydrate-Methane Vapor Phase Equilibria from Molecular Simulations

    DEFF Research Database (Denmark)

    Jensen, Lars; Thomsen, Kaj; von Solms, Nicolas


    Monte Carlo simulation methods for determining fluid- and crystal-phase chemical potentials are used for the first time to calculate liquid water-methane hydrate-methane vapor phase equilibria from knowledge of atomistic interaction potentials alone. The water and methane molecules are modeled...... potential of the zero-occupancy hydrate system using thermodynamic integration from an Einstein crystal reference state, and (iii) thermodynamic integration to obtain the water and guest molecules' chemical potentials as a function of the hydrate occupancy. The three-phase equilibrium curve is calculated...... value at corresponding conditions. While computationally intensive, simulations such as these are essential to map the thermodynamically stable conditions for hydrate systems....

  16. Phase diagrams of diblock copolymers in electric fields: a self-consistent field theory study. (United States)

    Wu, Ji; Wang, Xianghong; Ji, Yongyun; He, Linli; Li, Shiben


    We investigated the phase diagrams of diblock copolymers in external electrostatic fields by using real-space self-consistent field theory. The lamella, cylinder, sphere, and ellipsoid structures were observed and analyzed by their segment distributions, which were arranged to two types of phase diagrams to examine the phase behavior in weak and strong electric fields. One type was constructed on the basis of Flory-Huggins interaction parameter and volume fraction. We identified an ellipsoid structure with a body-centered cuboid arrangement as a stable phase and discussed the shift of phase boundaries in the electric fields. The other type of phase diagrams was established on the basis of the dielectric constants of two blocks in the electric fields. We then determined the regions of ellipsoid phase in the phase diagrams to examine the influence of dielectric constants on the phase transition between ellipsoidal and hexagonally packed cylinder phases. A general agreement was obtained by comparing our results with those described in previous experimental and theoretical studies.

  17. The water/n-octane/octyl-beta-D-glucoside/1-octanol system: phase diagrams and phase properties. (United States)

    Reimer, Johan; Nilsson, Markus; Alvarez Chamorro, Marta; Söderman, Olle


    The partial phase diagram of D2O/n-octyl-beta-D-alkyl-glucoside(C8G1)/n-octane has been determined at T=25 degrees C. The diagram contains a funnel-shaped micellar phase originating from the water corner of the phase diagram D2O/C8G1 with the stem forming a narrow three-phase region, in which the three phases in equilibrium are two microemulsions of similar composition and an excess oil phase. The microemulsions have been characterized with NMR self-diffusion measurements. At high surfactant concentration and no or low n-octane content, branched micelles exist. As the n-octane content is increased, discrete micelles are formed. Upon further addition of n-octane, the phase separation into two microemulsion phases is induced. Possible mechanisms causing the phase separation are discussed. The phase diagram of D2O/(C8G1)/1-octanol has been determined at 25 degrees C. Ten different phase regions were identified. The phases have been characterized with SAXS and deuterium heavy water NMR, and the swelling of the lamellar phase was investigated with SAXS.

  18. The Prognosis of the Phase Equilibrium Diagram of the System Al-Cu-Si


    Florentina Cziple


    The paper presents a model for establishing the mathematical functions of the liquidus and solidus curves, from the binary diagrams Al-Si, Si-Cu, Cu-Al and their use in the prognosis of the phase equilibrium diagram from the ternary system Al-Cu-Si. We have studied the model of the non-ideal liquid solution of the regular type. The calculus and graphic plotting of the equations for the binary systems has been performed on the computer

  19. Miscibility Phase Diagrams of Giant Vesicles Containing Sphingomyelin (United States)

    Veatch, Sarah L.; Keller, Sarah L.


    Saturated sphingomyelin (SM) lipids are implicated in lipid rafts in cell plasma membranes. Here we use fluorescence microscopy to observe coexisting liquid domains in vesicles containing SM, an unsaturated phosphatidylcholine lipid (either DOPC or POPC), and cholesterol. We note similar phase behavior in a model membrane mixture without SM (DOPC/DPPC/Chol), but find no micron-scale liquid domains in membranes of POPC/PSM/Chol. We delineate the onset of solid phases below the miscibility transition temperature, and detail indirect evidence for a three-phase coexistence of one solid and two liquid phases.

  20. Elasticity of methane hydrate phases at high pressure. (United States)

    Beam, Jennifer; Yang, Jing; Liu, Jin; Liu, Chujie; Lin, Jung-Fu


    Determination of the full elastic constants (cij) of methane hydrates (MHs) at extreme pressure-temperature environments is essential to our understanding of the elastic, thermodynamic, and mechanical properties of methane in MH reservoirs on Earth and icy satellites in the solar system. Here, we have investigated the elastic properties of singe-crystal cubic MH-sI, hexagonal MH-II, and orthorhombic MH-III phases at high pressures in a diamond anvil cell. Brillouin light scattering measurements, together with complimentary equation of state (pressure-density) results from X-ray diffraction and methane site occupancies in MH from Raman spectroscopy, were used to derive elastic constants of MH-sI, MH-II, and MH-III phases at high pressures. Analysis of the elastic constants for MH-sI and MH-II showed intriguing similarities and differences between the phases' compressional wave velocity anisotropy and shear wave velocity anisotropy. Our results show that these high-pressure MH phases can exhibit distinct elastic, thermodynamic, and mechanical properties at relevant environments of their respective natural reservoirs. These results provide new insight into the determination of how much methane exists in MH reservoirs on Earth and on icy satellites elsewhere in the solar system and put constraints on the pressure and temperature conditions of their environment.

  1. Phase Behaviour and Structural Aspects of Ternary Clathrate Hydrate Systems. The Role of Additives

    NARCIS (Netherlands)

    Mooijer-Van den Heuvel, M.M.


    In this study an experimental and modelling approach is applied to obtain fundamental insight into the phase behaviour of ternary systems, in which clathrate hydrates are formed. Proper interpretation of the phase behaviour requires knowledge on the clathrate hydrate structure in these systems,

  2. Conductivity, calorimetry and phase diagram of the NaHSO4–KHSO4 system

    DEFF Research Database (Denmark)

    Hind, Hamma-Cugny; Rasmussen, Søren Birk; Rogez, J.


    Physico-chemical properties of the binary system NaHSO4-KHSO4 were studied by calorimetry and conductivity, The enthalpy of mixing has been measured at 505 K in the full composition range and the phase diagram calculated. The phase diagram has also been constructed from phase transition...... temperatures obtained by conductivity for 10 different compositions and by differential thermal analysis. The phase diagram is of the simple eutectic type, where the eutectic is found to have the composition Χ(KHSO4)=0.44 (melting point ≈ 406 K). The conductivities in the liquid region have been fitted...... to polynomials of the form κ(X)=A(X)+B(X)(T-Tm)+C(X)(T-Tm)2, where Tm is the intermediate temperature of the measured temperature range and X, the mole fraction of KHSO4. The possible role of this binary system as a catalyst solvent is also discussed. (C) 2005 Elsevier B.V. All rights reserved....

  3. Equilibrium p-T phase diagram of boron: experimental study and thermodynamic analysis. (United States)

    Solozhenko, Vladimir L; Kurakevych, Oleksandr O


    Solid-state phase transformations and melting of high-purity crystalline boron have been in situ and ex situ studied at pressures to 20 GPa in the 1500-2500 K temperature range where diffusion processes become fast and lead to formation of thermodynamically stable phases. The equilibrium phase diagram of boron has been constructed based on thermodynamic analysis of experimental and literature data. The high-temperature part of the diagram contains p-T domains of thermodynamic stability of rhombohedral β-B106, orthorhombic γ-B28, pseudo-cubic (tetragonal) t'-B52, and liquid boron (L). The positions of two triple points have been experimentally estimated, i.e. β-t'-L at ~ 8.0 GPa and ~ 2490 K; and β-γ-t' at ~ 9.6 GPa and ~ 2230 K. Finally, the proposed phase diagram explains all thermodynamic aspects of boron allotropy and significantly improves our understanding of the fifth element.

  4. The topological pressure-temperature phase diagram of fluoxetine nitrate: monotropy unexpectedly turning into enantiotropy (United States)

    Céolin, René; Rietveld, Ivo B.


    The phase behavior of pharmaceuticals is important for regulatory requirements and dosage form development. Racemic fluoxetine nitrate possesses two crystalline forms for which initial measurements indicated that they have a monotropic relationship with form I the only stable form. By constructing the topological pressure-temperature phase diagram, it has been shown that unexpectedly form II has a stable domain in the phase diagram and can be easily obtained by heating and grinding. The pressure necessary to obtain form II is only 11 MPa, which is much lower than most pressure used for tableting in the pharmaceutical industry.

  5. Phase diagram of two-dimensional hard rods from fundamental mixed measure density functional theory. (United States)

    Wittmann, René; Sitta, Christoph E; Smallenburg, Frank; Löwen, Hartmut


    A density functional theory for the bulk phase diagram of two-dimensional orientable hard rods is proposed and tested against Monte Carlo computer simulation data. In detail, an explicit density functional is derived from fundamental mixed measure theory and freely minimized numerically for hard discorectangles. The phase diagram, which involves stable isotropic, nematic, smectic, and crystalline phases, is obtained and shows good agreement with the simulation data. Our functional is valid for a multicomponent mixture of hard particles with arbitrary convex shapes and provides a reliable starting point to explore various inhomogeneous situations of two-dimensional hard rods and their Brownian dynamics.

  6. Phase diagrams of vortex matter with multi-scale inter-vortex interactions in layered superconductors. (United States)

    Meng, Qingyou; Varney, Christopher N; Fangohr, Hans; Babaev, Egor


    It was recently proposed to use the stray magnetic fields of superconducting vortex lattices to trap ultracold atoms for building quantum emulators. This calls for new methods for engineering and manipulating of the vortex states. One of the possible routes utilizes type-1.5 superconducting layered systems with multi-scale inter-vortex interactions. In order to explore the possible vortex states that can be engineered, we present two phase diagrams of phenomenological vortex matter models with multi-scale inter-vortex interactions featuring several attractive and repulsive length scales. The phase diagrams exhibit a plethora of phases, including conventional 2D lattice phases, five stripe phases, dimer, trimer, and tetramer phases, void phases, and stable low-temperature disordered phases. The transitions between these states can be controlled by the value of an applied external field.

  7. Phase I (CATTS Theory), Phase II (Milne Point), Phase III (Hydrate Ridge)

    Energy Technology Data Exchange (ETDEWEB)

    None, None


    This study introduces a new type of cumulative seismic attribute (CATT) which quantifies gas hydrates resources in Hydrate Ridge offshore Oregon. CATT is base on case-specific transforms that portray hydrated reservoir properties. In this study we used a theoretical rock physics model to correct measured velocity log data.

  8. Existence of the phase drainage diagram in proton exchange membrane fuel cell fibrous diffusion media (United States)

    Medici, E. F.; Allen, J. S.

    It is well established that drainage in porous media can be characterized by two nondimensional numbers: the capillary number, Ca, and the viscosity ratio, M. Both quantities are useful to distinguish which force (viscous or capillary) is governing the fluid displacement behavior. This information is summarized in the Ca- M phase diagram. The Ca- M phase diagram is strongly dependent upon fluid properties and the porous medium morphology and wettability. Experimental evidence suggests that the morphology of the porous medium has an important role in the behavior in the fluid displacement. In this work, Ca- M phase diagram of fuel cell diffusion media layer (DM) is explored using a pseudo-Hele-Shaw experimental setup. This phase diagram will be explored together with the characteristic pressure curves of each displacement type. This Ca- M phase diagram will provide a fundamental resource for understanding the dynamics of the diffusion process and transport characteristics taking place inside of the DM as well as a characterization method for DMs.

  9. The phase diagram of scalar field theory on the fuzzy disc

    Energy Technology Data Exchange (ETDEWEB)

    Rea, Simone; Sämann, Christian [Maxwell Institute for Mathematical Sciences, Department of Mathematics,Heriot-Watt University,Colin Maclaurin Building, Riccarton, Edinburgh EH14 4AS (United Kingdom)


    Using a recently developed bootstrapping method, we compute the phase diagram of scalar field theory on the fuzzy disc with quartic even potential. We find three distinct phases with second and third order phase transitions between them. In particular, we find that the second order phase transition happens approximately at a fixed ratio of the two coupling constants defining the potential. We compute this ratio analytically in the limit of large coupling constants. Our results qualitatively agree with previously obtained numerical results.

  10. Kinetic Phase Diagrams of Ternary Al-Cu-Li System during Rapid Solidification: A Phase-Field Study. (United States)

    Yang, Xiong; Zhang, Lijun; Sobolev, Sergey; Du, Yong


    Kinetic phase diagrams in technical alloys at different solidification velocities during rapid solidification are of great importance for guiding the novel alloy preparation, but are usually absent due to extreme difficulty in performing experimental measurements. In this paper, a phase-field model with finite interface dissipation was employed to construct kinetic phase diagrams in the ternary Al-Cu-Li system for the first time. The time-elimination relaxation scheme was utilized. The solute trapping phenomenon during rapid solidification could be nicely described by the phase-field simulation, and the results obtained from the experiment measurement and/or the theoretical model were also well reproduced. Based on the predicted kinetic phase diagrams, it was found that with the increase of interface moving velocity and/or temperature, the gap between the liquidus and solidus gradually reduces, which illustrates the effect of solute trapping and tendency of diffusionless solidification.

  11. Phase behaviour and thermoelastic properties of ammonia hydrate and ice polymorphs from 0 - 2 GPa (United States)

    Fortes, A. D.; Wood, I. G.; Vocadlo, L.


    Ammonia remains amongst the most plausible planetary "antifreeze" agents, and its physical properties in hydrate compounds under the appropriate conditions (roughly 0 - 5 GPa, 100 - 300 K) must be known in order for it to be accommodated in planetary models. The pressure melting curve, and the expected polymorphism of the stoichiometric ammonia hydrates have implications for the internal structure of large icy moons like Titan, leading to phase layering and the possible persistence of deep subsurface oceans, the latter being sites of high astrobiological potential. Aqueous ammonia is also a candidate substance involved in cryomagmatism on Titan, and again the melting behaviour, and densities of liquids and solids, in the ammonia-water system must be known to model properly the partial melting and propagation of magma. We describe the results of a series of powder neutron diffraction experiments over the range 0 - 2.0 GPa, 150 - 280 K which were carried out with the objective of determining the phase behaviour and thermoelastic properties of ammonia dihydrate. In addition to the low-pressure cubic crystalline phase, ADH I, we have identified two closely related monoclinic polymorphs of ammonia dihydrate (ADH IIa and IIb) in the range 0.45 - 0.60 GPa (at 175 K), and have determined that this phase dissociates to a mixture of ammonia monohydrate phase II and ice II when warmed to ~190 K, which in turn melts at a binary eutectic at ~196 K; AMH II has a large (Z = 16) orthorhombic unit cell. Above 0.60 GPa, an orthorhombic polymorph of ammonia dihydrate, which we have referred to previously as ADH IV, persists to pressures > 3 GPa, and appears to be the liquidus phase over this whole pressure range. We have observed this phase co- existing with both ice II and ice VI. Here we describe the most plausible synthesis of the high-pressure phase diagram which explains our observations, and provide measurements of the densities, thermal expansion, bulk moduli, and crystal

  12. Elasticity of methane hydrate phases at high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Beam, Jennifer; Yang, Jing; Liu, Jin [Department of Geological Sciences, Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas 78712 (United States); Liu, Chujie [Laboratory of Seismology and Physics of Earth’s Interior, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui 230026 (China); Lin, Jung-Fu, E-mail: [Department of Geological Sciences, Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas 78712 (United States); Center for High Pressure Science and Advanced Technology Research (HPSTAR), Shanghai 201203 (China)


    Determination of the full elastic constants (c{sub ij}) of methane hydrates (MHs) at extreme pressure-temperature environments is essential to our understanding of the elastic, thermodynamic, and mechanical properties of methane in MH reservoirs on Earth and icy satellites in the solar system. Here, we have investigated the elastic properties of singe-crystal cubic MH-sI, hexagonal MH-II, and orthorhombic MH-III phases at high pressures in a diamond anvil cell. Brillouin light scattering measurements, together with complimentary equation of state (pressure-density) results from X-ray diffraction and methane site occupancies in MH from Raman spectroscopy, were used to derive elastic constants of MH-sI, MH-II, and MH-III phases at high pressures. Analysis of the elastic constants for MH-sI and MH-II showed intriguing similarities and differences between the phases′ compressional wave velocity anisotropy and shear wave velocity anisotropy. Our results show that these high-pressure MH phases can exhibit distinct elastic, thermodynamic, and mechanical properties at relevant environments of their respective natural reservoirs. These results provide new insight into the determination of how much methane exists in MH reservoirs on Earth and on icy satellites elsewhere in the solar system and put constraints on the pressure and temperature conditions of their environment.

  13. Color superconductivity. Phase diagrams and Goldstone bosons in the color-flavor locked phase

    Energy Technology Data Exchange (ETDEWEB)

    Kleinhaus, Verena


    The phase diagram of strongly interacting matter is studied with great experimental and theoretical effort and is one of the most fascinating research areas in modern particle physics. It is believed that color superconducting phases, in which quarks form Cooper pairs, appear at very high densities and low temperatures. Such phases could appear in the cores of neutron stars. In this work color superconducting phases are studied within the Nambu-Jona-Lasinio model. First of all, the phase diagram of neutral matter in beta equilibrium is calculated for two different diquark couplings. To this end, we determine the dynamical quark masses self-consistently together with the order parameters of color superconductivity. The interplay between neutrality and quark masses results in an interesting phase structure, in particular for the smaller diquark coupling. In the following, we additionally include a conserved lepton number to map the situation in the first few seconds of the evolution of a protoneutron star when neutrinos are trapped. This has a huge influence on the phase structure and favors the 2SC phase compared to the CFL phase. In the second part of this work we concentrate on the CFL phase which is characterized by a special symmetry breaking pattern. The properties of the resulting nine pseudoscalar Goldstone bosons (GB) are studied by solving the Bethe-Salpeter equation for quark-quark scattering. The GB are the lowest-lying excitations in the CFL phase and therefore play an important role for the thermodynamics of the system. The properties of the GB can also be described by the low-energy effective theory (LEET) for the CFL phase. There the respective low-energy constants are derived for asymptotically high densities where the strong force is weak and can be treated perturbatively. Our aim is the comparison of our results with these predictions, on the one hand to check our model in the weak-coupling limit and on the other hand to derive information about

  14. Phase diagram of coacervate complexes containing reversible coordination

    NARCIS (Netherlands)

    Wang, J.; Cohen Stuart, M.A.; Gucht, van der J.


    Phase separation of coacervate complexes from cationic PDMAEMA [poly(N,N-dimethylaminoethyl methacrylate)] and anionic reversible coordination polymers are studied in the present work. The coordination polymers are formed from zinc and a bis-ligand L2EO4

  15. Wetting phase diagrams of polyacid brush with a triple point.

    NARCIS (Netherlands)

    Mercurieva, A.A.; Iakovlev, P.A.; Zhulina, E.B.; Birshtein, T.M.; Leermakers, F.A.M.


    The (pre)wetting behavior of an annealed polyelectrolyte (PE) brush by an electrolyte solution that is strongly segregated from an apolar phase is analyzed. In this complex interface, there are interactions on various length scales. There are short-range interactions with the (uncharged) surface,

  16. First-Order Transitions and the Magnetic Phase Diagram of CeSb

    DEFF Research Database (Denmark)

    Lebech, Bente; Clausen, Kurt Nørgaard; Vogt, O.


    might exist in the magnetic phase diagram of CeSb at 16K for a field of approximately 0.3 T. The present study concludes that the transitions from the paramagnetic to the magnetically ordered states are of first order for fields below 0.8 T. Within the experimental accuracy no change has been observed......The high-temperature (14-17K) low-magnetic field (0-0.8 T) region of the phase diagram of the anomalous antiferromagnet CeSb has been reinvestigated by neutron diffraction in an attempt to locate a possible tricritical point. Previous neutron diffraction studies indicated that a tricritical point...

  17. Phase Diagrams of the Aqueous Two-Phase Systems of Poly(ethylene glycol)/Sodium Polyacrylate/Salts


    Adalberto Pessoa Junior; Hans-Olof Johansson; Eloi Feitosa


    Aqueous two-phase systems consisting of polyethylene glycol (PEG), sodium polyacrylate (NaPAA), and a salt have been studied. The effects of the polymer size, salt type (NaCl, Na2SO4, sodium adipate and sodium azelate) and salt concentrations on the position of the binodal curve were investigated. The investigated PEG molecules had a molar mass of 2,000 to 8,000 g/mol, while that of NaPAA was 8,000 g/mol. Experimental phase diagrams, and tie lines and calculated phase diagrams, based on Flory...

  18. Phase diagram study of a dimerized spin-S zig-zag ladder. (United States)

    Matera, J M; Lamas, C A


    The phase diagram of a frustrated spin-S zig-zag ladder is studied through different numerical and analytical methods. We show that for arbitrary S, there is a family of Hamiltonians for which a fully-dimerized state is an exact ground state, being the Majumdar-Ghosh point for a particular member of the family. We show that the system presents a transition between a dimerized phase to a Néel-like phase for S = 1/2, and spiral phases can appear for large S. The phase diagram is characterized by means of a generalization of the usual mean field approximation. The novelty in the present implementation is to consider the strongest coupled sites as the unit cell. The gap and the excitation spectrum is analyzed through the random phase approximation. Also, a perturbative treatment to obtain the critical points is discussed. Comparisons of the results with numerical methods like the Density Matrix Renormalization Group are also presented.

  19. T-p phase diagrams and the barocaloric effect in materials with successive phase transitions (United States)

    Gorev, M. V.; Bogdanov, E. V.; Flerov, I. N.


    An analysis of the extensive and intensive barocaloric effect (BCE) at successive structural phase transitions in some complex fluorides and oxyfluorides was performed. The high sensitivity of these compounds to a change in the chemical pressure allows one to vary the succession and parameters of the transformations (temperature, entropy, baric coefficient) over a wide range and obtain optimal values of the BCE. A comparison of different types of schematic T-p phase diagrams with the complicated T( p) dependences observed experimentally shows that in some ranges of temperature and pressure the BCE in compounds undergoing successive transformations can be increased due to a summation of caloric effects associated with distinct phase transitions. The maximum values of the extensive and intensive BCE in complex fluorides and oxyfluorides can be realized at rather low pressure (0.1-0.3 GPa). In a narrow temperature range around the triple points conversion from conventional BCE to inverse BCE is observed, which is followed by a gigantic change of both \\vertΔ S_BCE\\vert and \\vertΔ T_AD\\vert .

  20. Magnetic phase diagram and quantum phase transitions in a two-species boson model (United States)

    Belemuk, A. M.; Chtchelkatchev, N. M.; Mikheyenkov, A. V.; Kugel, K. I.


    We analyze the possible types of ordering in a boson-fermion model. The Hamiltonian is inherently related to the Bose-Hubbard model for vector two-species bosons in optical lattices. We show that such a model can be reduced to the Kugel-Khomskii type spin-pseudospin model, but in contrast to the usual version of the latter model, we are dealing here with the case of spin S =1 and pseudospin 1 /2 . We show that the interplay of spin and pseudospin degrees of freedom leads to a rather nontrivial magnetic phase diagram including the spin-nematic configurations. Tuning the spin-channel interaction parameter Us gives rise to quantum phase transitions. We find that the ground state of the system always has the pseudospin domain structure. On the other hand, the sign change of Us switches the spin arrangement of the ground state within domains from a ferro- to antiferromagnetic one. Finally, we revisit the spin (pseudospin)-1/2 Kugel-Khomskii model and see the inverse picture of phase transitions.

  1. Theory of multiple phase separations in binary mixtures: Phase diagrams, thermodynamic properties, and comparisons with experiments (United States)

    Goldstein, Raymond E.; Walker, James S.


    The lattice-gas models of phase separating binary liquid mixtures, introduced by Walker and Vause, are studied in detail and generalized within a high-temperature series expansion. This approximation allows for a straightforward study of rather complex, orientationally specific pair interactions, like those found in real systems. These theories can predict much of the complex miscibility phenomena often found in these mixtures, which are characterized by hydrogen-bonding interactions. Such phenomena include up to five critical solution points as a function of temperature. By comparisons with experiments, we determine the model parameters, thus mapping these experiments onto the global phase diagrams. These experiments include studies of the dependence of liquid/liquid miscibility on temperature, pressure, concentration of electrolytes, and addition of a dilute third component. Specifically, we make direct comparison with various experiments on the binary systems 2-butanol+H2O, 3-methyl pyridine+H2O(D2O), gylcerol +o- methoxy phenol and ethanol+H2O+electrolytes. Very simple and often easily interpreted trends in the parameters are found and quantitative agreement with experiments is possible with minimum parametric freedom. Explicit predictions of critical exponent renormalization in several systems are made. In addition, suggestions are made for a number of light scattering and specific heat experiments, some of which may demonstrate incipient critical behavior, such as the onset of long range correlations, in systems not undergoing phase separation.

  2. Magnetic phase diagram of magnetoelectric LiMnPO4

    DEFF Research Database (Denmark)

    Toft-Petersen, Rasmus; Andersen, Niels Hessel; Li, Haifeng


    The nature of the spin-flop (SF) transition in the magnetoelectric quasi-2D Heisenberg system LiMnPO4 is studied in fields applied along the a axis. A refinement of the magnetic structure using neutron diffraction data in the SF phase reveals that the spins reorient from being parallel...... to the a axis to be nearly along the c axis at magnetic fields between 4 and 4.7 T, depending on temperature. The low-field antiferromagnetic phase boundary is shown to join the spin-flop line tangentially at the so-called bicritical point, where there is a suppression of the ordering temperature....... At the bicritical field, we observe an increased intensity of the Lorentz broadened elastic scattering at magnetic Bragg peaks above TN as compared to zero field and 10 T, without an increase in peak width. This suggests an increased density of fluctuations at the bicritical field as compared to zero field....

  3. The Molybdenum titanium Phase Diagram Evaluated from Ab initio Calculations (United States)


    computational thermodynamics CALPHAD approach [13] and the Thermo-Calc software [14]. These studies led to two conflicting descriptions of the stability of...Department of Materials Science, NRCN, P.O.Box 9001, Beer-Sheva 84190, Israel. 2 Department of Mechanical Engineering and Materials Science, Duke University... thermodynamic properties of this binary system are not well known and two conflicting descriptions of the β-phase stability have been presented in the

  4. Phase Diagram Characterization Using Magnetic Beads as Liquid Carriers


    Blumenschein, Nicholas; Han, Daewoo; Steckl, Andrew J.


    Magnetic beads with ~1.9 µm average diameter were used to transport microliter volumes of liquids between contiguous liquid segments with a tube for the purpose of investigating phase change of those liquid segments. The magnetic beads were externally controlled using a magnet, allowing for the beads to bridge the air valve between the adjacent liquid segments. A hydrophobic coating was applied to the inner surface of the tube to enhance the separation between two liquid segments. The applied...

  5. Hydration Layer Coupling and Cooperativity in Phase Behavior of Stimulus Responsive Peptide Polymers (United States)

    Kurzbach, Dennis; Hassouneh, Wafa; McDaniel, Jonathan R.; Jaumann, Eva A.; Chilkoti, Ashutosh; Hinderberger, Dariush


    It is shown that hydrophilic (backbone) and hydrophobic (side chain) hydration layers of elastin-like polypeptides (ELPs), a class of stimulus responsive peptide polymers that exhibit lower critical solution temperature (LCST) phase transition behavior, can exist in a coupled and decoupled state. The decoupled hydration state consists of hydrophobic and hydrophilic hydration layers that respond independently to temperature while the coupled hydration state is characterized by a common, cooperative dehydration of both hydration layers. It is further shown that the primary sequence of an ELP can be tuned to exhibit either of the hydration layer coupling modes. Charged side chains lead to decoupling, while strongly hydrophobic side chains trigger stronger interaction between hydrophilic and hydrophobic hydration, leading to coupling of both layers. Further, for aprotic residues this coupling is fostered by decreasing bulkiness of hydrophobic side chains due to larger hydration numbers and water molecules mediating coupling between side chain and backbone hydration shells. For coupled hydration shells, the LCST phase transition characterized by spin probing continuous wave (CW) electron paramagnetic resonance (EPR) spectroscopy is reminiscent of a first order process even on nanoscopic length scales. In contrast, analogous synthetic polymers exhibit nanoscale phase transitions over a broad temperature range, indicating that their nanoscale phase behavior is not of first order. Hence, our results indicate that ELPs are the first identified class of polymers that exhibit a first-order inverse phase transition on nanoscopic length scales. These results may also provide insights into the role of hydration layers in governing the structure-function relationship of intrinsically disordered proteins. PMID:23822733

  6. METHODOLOGICAL NOTES: Metastable phases, phase transformations, and phase diagrams in physics and chemistry (United States)

    Brazhkin, Vadim V.


    Concepts of a 'phase' and a 'phase transition' are discussed for stable and metastable states of matter. While condensed matter physics primarily considers equilibrium states and treats metastable phases as exceptions, organic chemistry overwhelmingly deals with metastable states. It is emphasized that many simple light-element compounds — including most hydrocarbons; nitrogen oxides, hydrides, and carbides; carbon monoxide CO; alcohols and glycerin — are also metastable at normal pressure in the sense that they do not correspond to a minimum Gibbs free energy for a given chemical composition. At moderate temperatures and pressures, the phase transformations for these metastable phases are reversible with the fulfilment of all laws of equilibrium thermodynamics over the entire range of experimentally accessible times. At sufficiently high pressures (> 1-10 GPa), most of the metastable molecular phases irreversibly transform to lower-energy polymer phases, stable or metastable. These transitions do not correspond to the equality of the Gibbs free energy for the involved phases before and after the transition and so they are not first-order in the 'classical' sense. At normal pressure, the resulting polymer phases can exist at temperatures above the melting point of the original metastable molecular phase, as the examples of polyethylene and polymerized CO dramatically illustrate. As pressure is increased further to 20-50 GPa, the PV contribution to Gibbs free energy gives rise to stable high-density atomic phases. Many of the intermediate-energy polymer phases can likely be synthesized by methods of 'classical' chemistry at normal pressure.

  7. Phase diagram for the Eigen quasispecies theory with a truncated fitness landscape. (United States)

    Saakian, David B; Biebricher, Christof K; Hu, Chin-Kun


    Using methods of statistical physics, we present rigorous theoretical calculations of Eigen's quasispecies theory with the truncated fitness landscape which dramatically limits the available sequence space of information carriers. As the mutation rate is increased from small values to large values, one can observe three phases: the first (I) selective (also known as ferromagnetic) phase, the second (II) intermediate phase with some residual order, and the third (III) completely randomized (also known as paramagnetic) phase. We calculate the phase diagram for these phases and the concentration of information carriers in the master sequence (also known as peak configuration) x0 and other classes of information carriers. As the phase point moves across the boundary between phase I and phase II, x0 changes continuously; as the phase point moves across the boundary between phase II and phase III, x0 has a large change. Our results are applicable for the general case of a fitness landscape.

  8. The analysis of magnesium oxide hydration in three-phase reaction system (United States)

    Tang, Xiaojia; Guo, Lin; Chen, Chen; Liu, Quan; Li, Tie; Zhu, Yimin


    In order to investigate the magnesium oxide hydration process in gas-liquid-solid (three-phase) reaction system, magnesium hydroxide was prepared by magnesium oxide hydration in liquid-solid (two-phase) and three-phase reaction systems. A semi-empirical model and the classical shrinking core model were used to fit the experimental data. The fitting result shows that both models describe well the hydration process of three-phase system, while only the semi-empirical model right for the hydration process of two-phase system. The characterization of the hydration product using X-Ray diffraction (XRD) and scanning electron microscope (SEM) was performed. The XRD and SEM show hydration process in the two-phase system follows common dissolution/precipitation mechanism. While in the three-phase system, the hydration process undergo MgO dissolution, Mg(OH)2 precipitation, Mg(OH)2 peeling off from MgO particle and leaving behind fresh MgO surface.

  9. Water Phase Diagram Is Significantly Altered by Imidazolium Ionic Liquid

    DEFF Research Database (Denmark)

    Chaban, V. V.; Prezhdo, O. V.


    We report unusually large changes in the boiling temperature, saturated vapor pressure, and structure of the liquid-vapor interface for a range of 1-butyl-3-methyl tetrafluoroborate, [C4C1IM][BF4]-water mixtures. Even modest molar fractions of [C4C1IM][BF4] significantly affect the phase behavior...... of water, as represented, for instance, by strong negative deviations from Raoult's law, extending far beyond the standard descriptions. The investigation was carried out using classical molecular dynamics employing a specifically refined force field. The changes in the liquid-vapor interface and saturated...

  10. On a generalized phase diagram of simultaneous transport processes - a two velocity universal plane of invariance

    Energy Technology Data Exchange (ETDEWEB)

    Som, A. [General Electric Company, SC (United States)


    The problem concerning void fraction as an additional degree of freedom for a discontinuous density continuum e.g., two-phase systems, is theoretically investigated. A generalized phase diagram has been found to signify the evolution of two-phase systems. With due regard to the objective property of motion, the transformation functions and its properties clearly expose the invariance of relative velocity with superficial velocities as the vector quantities. A fundamental one-to-one mapping involving Euclidean point spaces has been derived demonstrating a two-velocity universal plane of invariance as two-phase equation-of-state. The utility of the phase diagram for steady-state operations is doubtless because of the fundamental property of motion. (author)

  11. Magnetoelectric phase diagrams of multiferroic GdMn2O5 (United States)

    Bukhari, S. H.; Kain, Th.; Schiebl, M.; Shuvaev, A.; Pimenov, Anna; Kuzmenko, A. M.; Wang, X.; Cheong, S.-W.; Ahmad, J.; Pimenov, A.


    Electric and magnetic properties of multiferroic GdMn2O5 in external magnetic fields were investigated to map out the magnetoelectric phases in this material. Due to strong magnetoelectric coupling, the dielectric permittivity is highly sensitive to phase boundaries in GdMn2O5 , which allowed us to construct the field-temperature phase diagrams. Several phase transitions are observed which are strongly field dependent with respect to field orientation and strength. The phase diagram for a magnetic field along the crystallographic a axis corresponds well to a polarization step, as induced by 90∘ rotation of Gd magnetic moments. Our results support the model of two ferroelectric sublattices, Mn-Mn and Gd-Mn, with strong R -Mn (4 f -3 d ) interaction for the polarization in R Mn2O5 .

  12. Phase diagram of the triangular extended Hubbard model. (United States)

    Tocchio, Luca F; Gros, Claudius; Zhang, Xue-Feng; Eggert, Sebastian


    We study the extended Hubbard model on the triangular lattice as a function of filling and interaction strength. The complex interplay of kinetic frustration and strong interactions on the triangular lattice leads to exotic phases where long-range charge order, antiferromagnetic order, and metallic conductivity can coexist. Variational Monte Carlo simulations show that three kinds of ordered metallic states are stable as a function of nearest neighbor interaction and filling. The coexistence of conductivity and order is explained by a separation into two functional classes of particles: part of them contributes to the stable order, while the other part forms a partially filled band on the remaining substructure. The relation to charge ordering in charge transfer salts is discussed.

  13. The NaNO2-NaNO3 system – a revised phase diagram

    DEFF Research Database (Denmark)

    Berg, Rolf W.; Kerridge, D.H.; Larsen, Peter Halvor


    Three earlier determinations of the phase diagram of the sodium nitrite/sodium nitrate binary system resulted in considerably different conclusions, ranging from simple eutectic to continuous solid solution types, together with different sub-solidus lines. Recent melting enthalpy measurements hav...

  14. Electronic phase diagram in the half-filled ionic Hubbard model with site-dependent interactions (United States)

    Hoang, Anh-Tuan; Nguyen, Thi-Hai-Yen; Le, Duc-Anh


    The ionic Hubbard model with spatially alternating interactions, which may be realized by cold atoms in optical lattices, is studied by mean of the coherent potential approximation. The paramagnetic phase diagram for the half-filled model at zero temperature is obtained. The possibility of enlarging an intermediate metallic region in the parameter space is addressed.

  15. Separable interactions and liquid 3He : V. Phase diagram in the presence of a Hubbard interaction

    NARCIS (Netherlands)

    Capel, H.W.; Nijhoff, F.W.; Breems, A. den


    A comparison is made between the various extrema of the Landau expansion of liquid 3He derived in a previous paper. As an application the phase diagram is investigated in the presence of an external magnetic field assuming that the Hubbard interaction is small as compared to the pairing interaction

  16. Phase diagrams on an unsignalized intersection for the cases of different maximum velocities of vehicles (United States)

    Li, Qi-Lang; Wang, Bing-Hong; Liu, Mu-Ren


    Using the cellular automaton traffic flow model, we investigate an unsignalized intersection which consists of two perpendicular one-lane roads. Both the roads cross at a point and the intersecting roads are cyclic. Each vehicle may pass or occupy the intersection where all the vehicles on both roads are not allowed to turn. Different from Ishibashi and Fukui's studies in which the update is carried out for both roads in turn, the parallel update is proposed and its detailed rules are presented in our model. In this work, the cases of different maximum vehicle velocities on both roads are considered. Based on simulation results and the principle for constructing phase diagrams, phase diagrams are mapped out and their specific flow formulas for all the regions in the phase diagrams are obtained for various vehicle densities, which are seldom done in previous studies. One also finds that the topology of phase diagrams depends on the update rules of eastbound and northbound roads and their maximum velocities of vehicles.

  17. Phase diagram and segregation of Ag-Co nanoalloys: insights from theory and simulation (United States)

    Zhao, Zheng; Fisher, Adrian; Cheng, Daojian


    Understanding the phase diagram is the first step to identifying the structure-performance relationship of a material at the nanoscale. In this work, a modified nanothermodynamical model has been developed to predict the phase diagrams of Ag-Co nanoalloys with the size of 1 ˜ 100 nm, which also overcomes the difference in the predicted results between theory and simulation for the first time. Based on this modified model, the phase diagrams of Ag-Co nanoalloys with various polyhedral morphologies (tetrahedron, cube, octahedron, decahedron, dodecahedron, rhombic dodecahedron, truncated octahedron, cuboctahedron, and icosahedron) have been predicted, showing good agreement with molecular dynamics simulations at the nanoscale of 1 ˜ 4 nm. In addition, the surface segregation of Ag-Co nanoalloys has been predicted with a Co-rich core/Ag-rich surface, which is also consistent with the simulation results. Our results highlight a useful roadmap for bridging the difference between theory and simulation in the prediction of the phase diagram at the nanoscale, which will help both theorists and experimentalists.

  18. State-of-the-art models for the phase diagram of carbon and diamond nucleation

    NARCIS (Netherlands)

    Ghiringhelli, L.M.; Valeriani, C.; Los, J.H.; Meijer, E.J.; Fasolino, A.; Frenkel, D.


    We review recent developments in the modelling of the phase diagram and the kinetics of crystallization of carbon. In particular, we show that a particular class of bond-order potentials (the so-called LCBOP models) account well for many of the known structural and thermodynamic properties of carbon

  19. Renormalization group improved computation of correlation functions in theories with nontrivial phase diagram

    DEFF Research Database (Denmark)

    Codello, Alessandro; Tonero, Alberto


    We present a simple and consistent way to compute correlation functions in interacting theories with nontrivial phase diagram. As an example we show how to consistently compute the four-point function in three dimensional Z2-scalar theories. The idea is to perform the path integral by weighting...

  20. Calculated Phase Diagram for the γ⇌α Transition in Ce

    DEFF Research Database (Denmark)

    Johansson, Børje; Abrikosov, I. A.; Aldén, Magnus


    We have calculated the pressure-temperature phase diagram of the γ⇌α isostructural transition in Ce on the basis of the Mott transition model. The theory correctly describes the linear variation of the transition temperature with pressure and the existence of a critical point. The quantitative ag...

  1. Phase diagram of the system Ca–Ti–O at 1200 K

    Indian Academy of Sciences (India)


    graphite anode and molten CaCl2 electrolyte. Keywords. Phase diagram; system Ca–Ti–O; calciothermic reduction of TiO2; reaction pathway. 1. Introduction. Although titanium and its alloys have excellent properties such as high strength, low density and very good corro- sion resistance, their use is restricted by high cost.

  2. Low-pressure phase diagram of crystalline benzene from quantum Monte Carlo

    CERN Document Server

    Azadi, Sam


    We study the low-pressure (0 to 10 GPa) phase diagram of crystalline benzene using quantum Monte Carlo (QMC) and density functional theory (DFT) methods. We consider the $Pbca$, $P4_32_12$, and $P2_1/c$ structures as the best candidates for phase I and phase II. We perform diffusion quantum Monte Carlo (DMC) calculations to obtain accurate static phase diagrams as benchmarks for modern van der Waals density functionals. We use density functional perturbation theory to compute phonon contribution in the free-energy calculations. Our DFT enthalpy-pressure phase diagram indicates that the $Pbca$ and $P2_1/c$ structures are the most stable phases within the studied pressure range. The DMC Gibbs free-energy calculations predict that the room temperature $Pbca$ to $P2_1/c$ phase transition occurs at 2.1(1) GPa. This prediction is consistent with available experimental results at room temperature. Our DMC calculations show an estimate of 50.6$\\pm$0.5 kJ/mol for crystalline benzene lattice energy.

  3. Calculation of the P-T phase diagram of nitrogen using a mean field model (United States)

    Enginer, Y.; Algul, G.; Yurtseven, H.


    The P-T phase diagram is calculated at low and moderate pressures by obtaining the phase line equations for the transitions considered in nitrogen using the Landau phenomenological model. For some transitions, a quadratic coupling between the order parameters is taken into account in the expansion of free energies in terms of the order parameters. A quadratic function in T and P is fitted to the experimental P-T data from the literature and the fitted parameters are determined. It is shown that the model studied here describes the observed data adequately, which can also be used to predict the thermodynamic properties of the phases of the molecular nitrogen within the temperatures and pressures of the P-T phase diagram of this system.

  4. Bifurcation analysis and phase diagram of a spin-string model with buckled states (United States)

    Ruiz-Garcia, M.; Bonilla, L. L.; Prados, A.


    We analyze a one-dimensional spin-string model, in which string oscillators are linearly coupled to their two nearest neighbors and to Ising spins representing internal degrees of freedom. String-spin coupling induces a long-range ferromagnetic interaction among spins that competes with a spin-spin antiferromagnetic coupling. As a consequence, the complex phase diagram of the system exhibits different flat rippled and buckled states, with first or second order transition lines between states. This complexity translates to the two-dimensional version of the model, whose numerical solution has been recently used to explain qualitatively the rippled to buckled transition observed in scanning tunneling microscopy experiments with suspended graphene sheets. Here we describe in detail the phase diagram of the simpler one-dimensional model and phase stability using bifurcation theory. This gives additional insight into the physical mechanisms underlying the different phases and the behavior observed in experiments.

  5. Phase diagrams of hexadecane-CO 2 mixtures from histogram-reweighting Monte Carlo (United States)

    Virnau, P.; Müller, M.; González MacDowell, L.; Binder, K.


    We investigate the phase behaviour of a hexadecane-CO 2 mixture with a coarse-grained off-lattice model. CO 2 is described by a single Lennard-Jones sphere and hexadecane by a chain of five LJ monomers with additional FENE interactions. Interaction parameters are derived from the critical points of pure hexadecane and CO 2 using a modified Lorentz-Berthelot mixing rule for the mixture. Simulations are based on grand-canonical histogram-reweighting Monte Carlo. A method to calculate interfacial tensions is described in detail. The analysis of the model includes simulated phase diagrams and interfacial tensions for pure hexadecane and CO 2 as well as a general phase diagram with complete critical lines for their mixture. We find evidence that a small change of interaction parameters between different species leads to qualitatively different phase behavior.

  6. The Prognosis of the Phase Equilibrium Diagram of the System Al-Cu-Si

    Directory of Open Access Journals (Sweden)

    Florentina Cziple


    Full Text Available The paper presents a model for establishing the mathematical functions of the liquidus and solidus curves, from the binary diagrams Al-Si, Si-Cu, Cu-Al and their use in the prognosis of the phase equilibrium diagram from the ternary system Al-Cu-Si. We have studied the model of the non-ideal liquid solution of the regular type. The calculus and graphic plotting of the equations for the binary systems has been performed on the computer

  7. Phase diagrams for an ideal gas mixture of fermionic atoms and bosonic molecules

    DEFF Research Database (Denmark)

    Williams, J. E.; Nygaard, Nicolai; Clark, C. W.


    We calculate the phase diagrams for a harmonically trapped ideal gas mixture of fermionic atoms and bosonic molecules in chemical and thermal equilibrium, where the internal energy of the molecules can be adjusted relative to that of the atoms by use of a tunable Feshbach resonance. We plot...... diagrams obtained in recent experiments on the Bose-Einstein condensation to Bardeen-Cooper-Schrieffer crossover, in which the condensate fraction is plotted as a function of the initial temperature of the Fermi gas measured before a sweep of the magnetic field through the resonance region....

  8. Pilot scale experiments of magnesia hydration under gas-liquid-solid (three-phase) reaction system (United States)

    Tang, Xiaojia; Lv, Qiwei; Yin, Lin; Nie, Yixing; Jin, Qi; Ji, Yangyuan; Zhu, Yimin


    Pilot scale experiments were conducted to prepare magnesium hydroxide by magnesia hydration under gas-liquid-solid (three-phase) reaction system. The effect of reaction pressure, reactivity and particle size of magnesia and the concentration of the pulp on the degree of hydration was investigated. The results indicated that the hydration reaction occurred at the first 30min mainly. During the set reaction condition, degree of hydration of 68% could be obtained at the reaction pressure of 0.2MPa, concentration of pulp of 5%w/w with high reactivity and fine powder. The promotion effect on the degree of hydration caused by the three-phase reaction system was mostly attributed to the exfoliation of steam.

  9. The p-T phase diagram for ferroelectric bis-thiourea pyridinium nitrate

    Energy Technology Data Exchange (ETDEWEB)

    Bilski, P. [Faculty of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznan (Poland); Czarnecki, P., E-mail: [Faculty of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznan (Poland); Lewicki, S.; Wasicki, J. [Faculty of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznan (Poland)


    Highlights: > Bis-thiourea pyridinium nitrate has been studied at high pressures up to 1 GPa. > p-T phase diagram has been obtained by NMR and dielectric method. > The triple point is observed in p-T diagram. > The continuous phase transition is changed to discontinuous at the pressure 450 Mpa. - Abstract: The effect of temperature and pressure on physical properties of the ferroelectric bis-thiourea pyridinium nitrate inclusion compound has been studied by dielectric spectroscopy and nuclear magnetic resonance (NMR). At ambient pressure the ferroparaelectric phase transition observed at T{sub 2} = 216 K is continuous in contrast to the nonferroelectric phase transition observed at T{sub 1} = 273 K. Under small pressures, the temperatures of the phase transitions T{sub 1} and T{sub 2} increase with increasing pressure. Starting from about 250 MPa, T{sub 1} temperature decreases with increasing pressure, while T{sub 2} temperature increases with increasing pressure. At 450 MPa and 245 K a triple point is observed. Bis-thiourea pyridinium nitrate undergoes a continuous phase transition from the ferroelectric to paraelectric phase under 450 MPa, while above this pressure the phase transition from the ferroelectric to paraelectric phase is discontinuous. The change in the phase transition character is related to the crystallographic change in the group-subgroup relation between the ferro- and paraelectric phases taking place with increasing pressure.

  10. Prediction of the phase equilibria of methane hydrates using the direct phase coexistence methodology

    Energy Technology Data Exchange (ETDEWEB)

    Michalis, Vasileios K.; Costandy, Joseph; Economou, Ioannis G., E-mail: [Chemical Engineering Program, Texas A and M University at Qatar, P.O. Box 23847, Doha (Qatar); Tsimpanogiannis, Ioannis N.; Stubos, Athanassios K. [Environmental Research Laboratory, National Center for Scientific Research NCSR “Demokritos,” Aghia Paraskevi, Attiki GR-15310 (Greece)


    The direct phase coexistence method is used for the determination of the three-phase coexistence line of sI methane hydrates. Molecular dynamics (MD) simulations are carried out in the isothermal–isobaric ensemble in order to determine the coexistence temperature (T{sub 3}) at four different pressures, namely, 40, 100, 400, and 600 bar. Methane bubble formation that results in supersaturation of water with methane is generally avoided. The observed stochasticity of the hydrate growth and dissociation processes, which can be misleading in the determination of T{sub 3}, is treated with long simulations in the range of 1000–4000 ns and a relatively large number of independent runs. Statistical averaging of 25 runs per pressure results in T{sub 3} predictions that are found to deviate systematically by approximately 3.5 K from the experimental values. This is in good agreement with the deviation of 3.15 K between the prediction of TIP4P/Ice water force field used and the experimental melting temperature of ice Ih. The current results offer the most consistent and accurate predictions from MD simulation for the determination of T{sub 3} of methane hydrates. Methane solubility values are also calculated at the predicted equilibrium conditions and are found in good agreement with continuum-scale models.

  11. Hydrate Phase Assemblages in Blends of Ye'elimite and Gypsum with Alite and Belite

    DEFF Research Database (Denmark)

    Pedersen, Malene Thostrup; Skibsted, Jørgen

    Calcium sulpho-aluminate (CSA) cements all contain ye’elimite, either as the main phase or in intermediate amounts, while they differ in their content of accessory phases. Belite is the main phase in most CSA cements, however, alite - CSA cements have been produced. The hydrate phases formed during...

  12. Hydrate Phase Assemblages in Blends of Ye’elimite and Gypsum with Alite and Belite

    DEFF Research Database (Denmark)

    Pedersen, Malene Thostrup; Skibsted, Jørgen


    Calcium sulpho-aluminate (CSA) cements all contain ye’elimite, either as the main phase or in intermediate amounts, while they differ in their content of accessory phases. Belite is the main phase in most CSA cements, however, alite - CSA cements have been produced. The hydrate phases formed during...

  13. Experimental Approach to the QCD Phase Diagram - Beam Energy Scan at RHIC (United States)

    Odyniec, G.


    The QCD phase diagram appears to be the most important single figure of our field. While recent progress in Lattice QCD (LQCD) and model calculations is impressive, the location of phase boundaries and the exact position of the hypothetical critical point (CP) remains unknown. The available theoretical estimates, however, indicate that the critical point might be in the region of the phase diagram probed by current heavy ion experiments. The Beam Energy Scan (BES) program at RHIC, described in this paper, was launched to expand the experimental study where theory cannot yet reach. Both large RHIC experiments, STAR and PHENIX, are in the process of preparing for the first run. Particularly STAR with its large, uniform acceptance and excellent particle identification capabilities, is uniquely positioned to cover this physics in unprecedented depth and detail.

  14. Origin of Invariant Gel Melting Temperatures in the c-T Phase Diagram of an Organogel. (United States)

    Christ, Elliot; Blanc, Christophe; Al Ouahabi, Abdelaziz; Maurin, David; Le Parc, Rozenn; Bantignies, Jean-Louis; Guenet, Jean-Michel; Collin, Dominique; Mésini, Philippe J


    Binary c-T phase diagrams of organogelators in solvent are frequently simplified to two domains, gel and sol, even when the melting temperatures display two distinct regimes, an increase with T and a plateau. Herein, the c-T phase diagram of an organogelator in solvent is elucidated by rheology, DSC, optical microscopy, and transmitted light intensity measurements. We evidence a miscibility gap between the organogelator and the solvent above a threshold concentration, cL. In this domain the melting or the formation of the gel becomes a monotectic transformation, which explains why the corresponding temperatures are nonvariant above cL. As shown by further studies by variable temperature FTIR and NMR, different types of H-bonds drive both the liquid-liquid phase separation and the gelation.

  15. Isomorphs in the phase diagram of a model liquid without inverse power law repulsion

    DEFF Research Database (Denmark)

    Veldhorst, Arnold Adriaan; Bøhling, Lasse; Dyre, J. C.


    the dynamics of the viscous Buckingham liquid is mimicked by a corresponding model with purely repulsive inverse-power-law interactions. The results presented here closely resemble earlier results for Lennard-Jones type liquids, demonstrating that the existence of strong correlations and isomorphs does......It is demonstrated by molecular dynamics simulations that liquids interacting via the Buckingham potential are strongly correlating, i.e., have regions of their phase diagram where constant-volume equilibrium fluctuations in the virial and potential energy are strongly correlated. A binary...... Buckingham liquid is cooled to a viscous phase and shown to have isomorphs, which are curves in the phase diagram along which structure and dynamics in appropriate units are invariant to a good approximation. To test this, the radial distribution function, and both the incoherent and coherent intermediate...

  16. Considerations Concerning Matrix Diagram Transformations Associated with Mathematical Model Study of a Three-phase Transformer

    Directory of Open Access Journals (Sweden)

    Mihaela Poienar


    Full Text Available The clock hour figure mathematical model of a threephase transformer can be expressed, in the most plain form, through a 3X3 square matrix, called code matrix. The lines position reflect the modification in the high voltage windings terminal and the columns position reflect the modification in the low voltage winding terminal. The main changes on the transformer winding terminal are: the circular permutation of connection between windings; terminal supply reversal; reverse direction for the phase winding wrapping; reversal the beginning with the end for a phase winding; the connection conversion from N in Z between phase winding or inverse. The analytical form of these changes actually affect the configuration of the mathematical model expressed through a transformations diagram proposed and analyzed in two ways: bipolar version and unipolar version (fanwise. In the end of the paper are presented about the practical exploitation of the transformations diagram.

  17. How little data is enough? Phase-diagram analysis of sparsity-regularized X-ray computed tomography

    DEFF Research Database (Denmark)

    Jørgensen, Jakob Sauer; Sidky, E. Y.


    We introduce phase-diagram analysis, a standard tool in compressed sensing (CS), to the X-ray computed tomography (CT) community as a systematic method for determining how few projections suffice for accurate sparsity-regularized reconstruction. In CS, a phase diagram is a convenient way to study...... and express certain theoretical relations between sparsity and sufficient sampling. We adapt phase-diagram analysis for empirical use in X-ray CT for which the same theoretical results do not hold. We demonstrate in three case studies the potential of phase-diagram analysis for providing quantitative answers...... measurements does not lead to improved performance compared with standard structured sampling patterns. Finally, we show preliminary results of how well phase-diagram analysis can predict the sufficient number of projections for accurately reconstructing a large-scale image of a given sparsity by means...

  18. Application of quaternary phase diagrams to compound semiconductor processing. Progress report, April 1, 1988--December 31, 1988

    Energy Technology Data Exchange (ETDEWEB)

    Schwartzman, A.


    This paper considers the application of quaternary phase diagrams to understanding and predicting the behavior of II-VI thin film interfaces in photovoltaic devices under annealing conditions. Examples, listed in a table, include semiconductor/insulator/semiconductor (SIS) layered structures, II-VI/II-VI and III-V/II-VI epitaxial heterojunctions and oxidation of ternary compounds. Solid solubility is taken into account for quaternary phase diagrams of semiconductor systems. Using free energies of formation, a method to calculate the quaternary phase diagrams was developed. The Ga-As-II-VI and Cd-Te-Zn-O phase diagrams are reviewed as examples of quaternary phase diagrams without and with solid solubility.

  19. Effect of organic matter on CO(2) hydrate phase equilibrium in phyllosilicate suspensions. (United States)

    Park, Taehyung; Kyung, Daeseung; Lee, Woojin


    In this study, we examined various CO2 hydrate phase equilibria under diverse, heterogeneous conditions, to provide basic knowledge for successful ocean CO2 sequestration in offshore marine sediments. We investigated the effect of geochemical factors on CO2 hydrate phase equilibrium. The three-phase (liquid-hydrate-vapor) equilibrium of CO2 hydrate in the presence of (i) organic matter (glycine, glucose, and urea), (ii) phyllosilicates [illite, kaolinite, and Na-montmorillonite (Na-MMT)], and (iii) mixtures of them was measured in the ranges of 274.5-277.0 K and 14-22 bar. Organic matter inhibited the phase equilibrium of CO2 hydrate by association with water molecules. The inhibition effect decreased in the order: urea phase equilibrium, while Na-MMT (expandable clay) affected the phase equilibrium because of its interlayer cations. The CO2 hydrate equilibrium conditions, in the illite and kaolinite suspensions with organic matter, were very similar to those in the aqueous organic matter solutions. However, the equilibrium condition in the Na-MMT suspension with organic matter changed because of reduction of its inhibition effect by intercalated organic matter associated with cations in the Na-MMT interlayer.

  20. Identification of phases of various oil, surfactant/ co-surfactants and water system by ternary phase diagram. (United States)

    Syed, Haroon K; Peh, Kok K


    The objective of this study was to select appropriate surfactants or blends of surfactants and oil to study the ternary phase diagram behavior and identify various phases obtained from the oil and surfactant/surfactant mixture combinations of different HLB. The phases include conventional emulsion, gel/viscous and transparent/translucent microemulsion. Pseudoternary phase diagrams of water, oil and S/Smix of various HLB values range of 9.65-15 were constructed by using water titration method at room temperature. Visual analysis, conductivity and dye dilution test (methylene blue) were performed after each addition and mixing of water, to identify phases as microemulsion, o/w or w/o emulsion (turbid/milky) and transparent gel/turbid viscous. High gel or viscous area was obtained with Tween 80 and surfactant mixture of Tween 80 and Span 80 with all oils. The results indicated that non-ionic surfactants and PG of different HLB values exhibited different pseudoternary phase diagram characteristics but no microemulsions originated from mineral and olive oils. The w/o emulsion occupied a large area in the ternary phase triangle when HLB value of the surfactant/Smix decreased. The o/w emulsion area was large with increasing HLB value of surfactant/Smix.

  1. Thermodynamic calculations in the system CH4-H2O and methane hydrate phase equilibria (United States)

    Circone, S.; Kirby, S.H.; Stern, L.A.


    Using the Gibbs function of reaction, equilibrium pressure, temperature conditions for the formation of methane clathrate hydrate have been calculated from the thermodynamic properties of phases in the system CH4-H 2O. The thermodynamic model accurately reproduces the published phase-equilibria data to within ??2 K of the observed equilibrium boundaries in the range 0.08-117 MPa and 190-307 K. The model also provides an estimate of the third-law entropy of methane hydrate at 273.15 K, 0.1 MPa of 56.2 J mol-1 K-1 for 1/n CH4??H 2O, where n is the hydrate number. Agreement between the calculated and published phase-equilibria data is optimized when the hydrate composition is fixed and independent of the pressure and temperature for the conditions modeled. ?? 2006 American Chemical Society.

  2. Inhibited phase behavior of gas hydrates in graphene oxide: influences of surface and geometric constraints. (United States)

    Kim, Daeok; Kim, Dae Woo; Lim, Hyung-Kyu; Jeon, Jiwon; Kim, Hyungjun; Jung, Hee-Tae; Lee, Huen


    Porous materials have provided us unprecedented opportunities to develop emerging technologies such as molecular storage systems and separation mechanisms. Pores have also been used as supports to contain gas hydrates for the application in gas treatments. Necessarily, an exact understanding of the properties of gas hydrates in confining pores is important. Here, we investigated the formation of CO2, CH4 and N2 hydrates in non-interlamellar voids in graphene oxide (GO), and their thermodynamic behaviors. For that, low temperature XRD and P-T traces were conducted to analyze the water structure and confirm hydrate formation, respectively, in GO after its exposure to gaseous molecules. Confinement and strong interaction of water with the hydrophilic surface of graphene oxide reduce water activity, which leads to the inhibited phase behavior of gas hydrates.

  3. Lyapunov exponents and phase diagrams reveal multi-factorial control over TRAIL-induced apoptosis. (United States)

    Aldridge, Bree B; Gaudet, Suzanne; Lauffenburger, Douglas A; Sorger, Peter K


    Receptor-mediated apoptosis proceeds via two pathways: one requiring only a cascade of initiator and effector caspases (type I behavior) and the second requiring an initiator-effector caspase cascade and mitochondrial outer membrane permeabilization (type II behavior). Here, we investigate factors controlling type I versus II phenotypes by performing Lyapunov exponent analysis of an ODE-based model of cell death. The resulting phase diagrams predict that the ratio of XIAP to pro-caspase-3 concentrations plays a key regulatory role: type I behavior predominates when the ratio is low and type II behavior when the ratio is high. Cell-to-cell variability in phenotype is observed when the ratio is close to the type I versus II boundary. By positioning multiple tumor cell lines on the phase diagram we confirm these predictions. We also extend phase space analysis to mutations affecting the rate of caspase-3 ubiquitylation by XIAP, predicting and showing that such mutations abolish all-or-none control over activation of effector caspases. Thus, phase diagrams derived from Lyapunov exponent analysis represent a means to study multi-factorial control over a complex biochemical pathway.

  4. Equilibrium p-T Phase Diagram of Boron: Experimental Study and Thermodynamic Analysis (United States)

    Solozhenko, Vladimir L.; Kurakevych, Oleksandr O.


    Solid-state phase transformations and melting of high-purity crystalline boron have been in situ and ex situ studied at pressures to 20 GPa in the 1500–2500 K temperature range where diffusion processes become fast and lead to formation of thermodynamically stable phases. The equilibrium phase diagram of boron has been constructed based on thermodynamic analysis of experimental and literature data. The high-temperature part of the diagram contains p-T domains of thermodynamic stability of rhombohedral β-B106, orthorhombic γ-B28, pseudo-cubic (tetragonal) t'-B52, and liquid boron (L). The positions of two triple points have been experimentally estimated, i.e. β–t'–L at ~ 8.0 GPa and ~ 2490 K; and β–γ–t' at ~ 9.6 GPa and ~ 2230 K. Finally, the proposed phase diagram explains all thermodynamic aspects of boron allotropy and significantly improves our understanding of the fifth element. PMID:23912523

  5. Using Fluid Inclusions to Bring Phase Diagrams to Life in a Guided Inquiry Instructional Setting (United States)

    Farver, J. R.; Onasch, C.


    A fundamental concept in mineralogy, petrology, and geochemistry is the generation and interpretation of phase diagrams for various systems. We have developed an exercise to strengthen student's familiarity with and confidence in employing phase diagrams by using fluid inclusions. The activity follows the 5Es (Engagement, Exploration, Explanation, Extension, Evaluation) guided inquiry instructional model in order to best facilitate student learning. The exercise follows an activity adapted from Brady (1992) wherein students collect data to generate the phase diagram for the Ice-Water-NaCl system. The engagement activity involves using a USGS-type fluid inclusion heating-cooling stage with a camera and projection system. We typically employ either a doubly-polished quartz sample or a cleaved section of fluorite and select a typical two phase (L + V) aqueous inclusion. Students first observe the inclusion at room temperature and pressure and are asked to predict what would happen if the sample is heated. Students then watch as the sample is heated to its homogenization temperature (Th) and are asked to explain what they see. The sample is then cooled until completely frozen and then slowly warmed until the first ice melting (at the eutectic, Te) and then until all ice melts (Tm). Again, students are asked to explain what they see and, if necessary, they are guided to remember the earlier phase diagram activity. The process is then repeated while students follow along the appropriate phase diagrams. In this fashion, students literally see the changes in phases present and their relative abundances as they move through the phase diagram. The engagement activity generates student interest in the exercise to insure minds-on as well as hands-on exploration. The exploration activities involve students observing and describing a wide range of fluid inclusion types (e.g., CO2, daughter crystals, multiple inclusion trails, etc) and hands-on collection of Th and Tm data for a

  6. Topological Phase Diagrams of Bulk and Monolayer TiS2−xTex

    KAUST Repository

    Zhu, Zhiyong


    With the use of ab initio calculations, the topological phase diagrams of bulk and monolayer TiS2−xTex are established. Whereas bulk TiS2−xTex shows two strong topological phases [1;(000)] and [1;(001)] for 0.44phases in three and two dimensions simultaneously.

  7. Stepwise shock compression with relation to phase diagram of C70 fullerite (United States)

    Borodina, Tatiana; Khishchenko, Konstantin; Milyavskiy, Vladimir


    Phase transitions of C70 fullerite with different initial phase compositions under stepwise shock compression are experimentally studied to pressure of 52 GPa and temperature of about 1700 K. The crystalline phase of fullerite C70 with a hexagonal close-packed structure remain practically unchanged under stepwise shock loading up to pressure of 8 GPa. Shock-induced transformation of the hexagonal phase into the face centered cubic phase is observed at pressures in the range 9 to 23.5 GPa. The amount of transformed material increases with the shock intensity. Upon further increase of the shock pressure, the destruction of C70 molecules occurs. This destruction is accompanied by a formation of the graphite phase of carbon. Pressure--temperature history of C70 specimens is estimated with the use of equation of state C60 fullerite [K.V. Khishchenko et al. Diamond and Relat. Mat. 2007 (16) 1204]. Analyzing this pressure-temperature history along with the tentative phase diagram of C70 [B. Sundqvist. Advances in Phys. 1999 (48) 1], we conclude that the observed conversion of the hexagonal to the cubic phase can not be described in the framework of this diagram.

  8. Magnetic transition phase diagram of cobalt clusters electrodeposited on HOPG: Experimental and micromagnetic modelling study

    Energy Technology Data Exchange (ETDEWEB)

    Rivera, M., E-mail: mrivera@fisica.unam.m [Imperial College London, Department of Chemistry, South Kensington Campus, London SW7 2AZ (United Kingdom); Rios-Reyes, C.H. [Universidad Autonoma Metropolitana-Azcapotzalco, Departamento de Materiales, Av. San Pablo 180, Col. Reynosa Tamaulipas, C.P. 02200, Mexico D.F. (Mexico); Universidad Autonoma del Estado de Hidalgo, Centro de Investigaciones Quimicas, Mineral de la Reforma, Hidalgo, C.P. 42181 (Mexico); Mendoza-Huizar, L.H. [Universidad Autonoma del Estado de Hidalgo, Centro de Investigaciones Quimicas, Mineral de la Reforma, Hidalgo, C.P. 42181 (Mexico)


    The magnetic transition from mono- to multidomain magnetic states of cobalt clusters electrodeposited on highly oriented pyrolytic graphite electrodes was studied experimentally using Magnetic Force Microscopy. From these images, it was found that the critical size of the magnetic transition is dominated by the height rather than the diameter of the aggregate. This experimental behavior was found to be consistent with a theoretical single-domain ferromagnetic model that states that a critical height limits the monodomain state. By analyzing the clusters magnetic states as a function of their dimensions, magnetic exchange constant and anisotropy value were obtained and used to calculate other magnetic properties such as the exchange length, magnetic wall thickness, etc. Finally, a micromagnetic simulation study correctly predicted the experimental magnetic transition phase diagram. - Research highlights: > Electrodeposition of cobalt clusters. > Mono to multidomain magnetic transition. > Magnetic phase diagram.

  9. Phase diagram of structure of radial electric field in helical plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Toda, S.; Itoh, K.


    A set of transport equations in toroidal helical plasmas is analyzed, including the bifurcation of the radial electric field. Multiple solutions of E{sub r} for the ambipolar condition induces domains of different electric polarities. A structure of the domain interface is analyzed and a phase diagram is obtained in the space of the external control parameters. The region of the reduction of the anomalous transport is identified. (author)

  10. Phase diagram of the two-dimensional negative-U Hubbard model (United States)

    Scalettar, R. T.; Loh, E. Y.; Gubernatis, J. E.; Moreo, A.; White, S. R.


    Theoretical arguments and numerical calculations are used to discuss the phase diagram of the two-dimensional negative-U Hubbard model. The results are consistent with (1) a vanishing transition temperature at half-filling but with a ground state having both superconducting and charge-density-wave long-range order, and (2) a Kosterlitz-Thouless transition at a finite temperature into a superconducting state with power-law decay of the pairing correlations away from half-filling.

  11. Insulator-insulator and insulator-conductor transitions in the phase diagram of aluminium trichloride

    Directory of Open Access Journals (Sweden)

    Romina Ruberto


    Full Text Available We report a classical computer-simulation study of the phase diagram of AlCl3 in the pressure-temperature (p, T plane, showing (i that melting from a layered crystal structure occurs into a molecular liquid at low (p, T and into a dissociated ionic liquid at high (p, T, and (ii that a broad transition from a molecular insulator to an ionic conductor takes place in the liquid state.

  12. Urea-temperature phase diagrams capture the thermodynamics of denatured state expansion that accompany protein unfolding (United States)

    Tischer, Alexander; Auton, Matthew


    We have analyzed the thermodynamic properties of the von Willebrand factor (VWF) A3 domain using urea-induced unfolding at variable temperature and thermal unfolding at variable urea concentrations to generate a phase diagram that quantitatively describes the equilibrium between native and denatured states. From this analysis, we were able to determine consistent thermodynamic parameters with various spectroscopic and calorimetric methods that define the urea–temperature parameter plane from cold denaturation to heat denaturation. Urea and thermal denaturation are experimentally reversible and independent of the thermal scan rate indicating that all transitions are at equilibrium and the van't Hoff and calorimetric enthalpies obtained from analysis of individual thermal transitions are equivalent demonstrating two-state character. Global analysis of the urea–temperature phase diagram results in a significantly higher enthalpy of unfolding than obtained from analysis of individual thermal transitions and significant cross correlations describing the urea dependence of and that define a complex temperature dependence of the m-value. Circular dichroism (CD) spectroscopy illustrates a large increase in secondary structure content of the urea-denatured state as temperature increases and a loss of secondary structure in the thermally denatured state upon addition of urea. These structural changes in the denatured ensemble make up ∼40% of the total ellipticity change indicating a highly compact thermally denatured state. The difference between the thermodynamic parameters obtained from phase diagram analysis and those obtained from analysis of individual thermal transitions illustrates that phase diagrams capture both contributions to unfolding and denatured state expansion and by comparison are able to decipher these contributions. PMID:23813497

  13. Phase diagram of the uniaxial and biaxial soft-core Gay-Berne model. (United States)

    Berardi, Roberto; Lintuvuori, Juho S; Wilson, Mark R; Zannoni, Claudio


    Classical molecular dynamics simulations have been used to explore the phase diagrams for a family of attractive-repulsive soft-core Gay-Berne models [R. Berardi, C. Zannoni, J. S. Lintuvuori, and M. R. Wilson, J. Chem. Phys. 131, 174107 (2009)] and determine the effect of particle softness, i.e., of a moderately repulsive short-range interaction, on the order parameters and phase behaviour of model systems of uniaxial and biaxial ellipsoidal particles. We have found that isotropic, uniaxial, and biaxial nematic and smectic phases are obtained for the model. Extensive calculations of the nematic region of the phase diagram show that endowing mesogenic particles with such soft repulsive interactions affect the stability range of the nematic phases, and in the case of phase biaxiality it also shifts it to lower temperatures. For colloidal particles, stabilised by surface functionalisation, (e.g., with polymer chains), we suggest that it should be possible to tune liquid crystal behaviour to increase the range of stability of uniaxial and biaxial phases (by varying solvent quality). We calculate second virial coefficients and show that they are a useful means of characterising the change in effective softness for such systems. For thermotropic liquid crystals, the introduction of softness in the interactions between mesogens with overall biaxial shape (e.g., through appropriate conformational flexibility) could provide a pathway for the actual chemical synthesis of stable room-temperature biaxial nematics. © 2011 American Institute of Physics

  14. Hydration, hydration, hydration

    National Research Council Canada - National Science Library

    Miller, Veronica S; Bates, Graham P


    .... Although the importance of adequate hydration in combating heat stress is universally recognized, studies in a range of worker groups have demonstrated a disturbingly poor hydration level in a high...

  15. Phase Diagrams of the Aqueous Two-Phase Systems of Poly(ethylene glycol/Sodium Polyacrylate/Salts

    Directory of Open Access Journals (Sweden)

    Adalberto Pessoa Junior


    Full Text Available Aqueous two-phase systems consisting of polyethylene glycol (PEG, sodium polyacrylate (NaPAA, and a salt have been studied. The effects of the polymer size, salt type (NaCl, Na2SO4, sodium adipate and sodium azelate and salt concentrations on the position of the binodal curve were investigated. The investigated PEG molecules had a molar mass of 2,000 to 8,000 g/mol, while that of NaPAA was 8,000 g/mol. Experimental phase diagrams, and tie lines and calculated phase diagrams, based on Flory-Huggins theory of polymer solutions are presented. Due to strong enthalpic and entropic balancing forces, the hydrophobicity of the added salt has a strong influence on the position of the binodal, which could be reproduced by model calculations.

  16. Handbook of gas hydrate properties and occurrence

    Energy Technology Data Exchange (ETDEWEB)

    Kuustraa, V.A.; Hammershaimb, E.C.


    This handbook provides data on the resource potential of naturally occurring hydrates, the properties that are needed to evaluate their recovery, and their production potential. The first two chapters give data on the naturally occurring hydrate potential by reviewing published resource estimates and the known and inferred occurrences. The third and fourth chapters review the physical and thermodynamic properties of hydrates, respectively. The thermodynamic properties of hydrates that are discussed include dissociation energies and a simplified method to calculate them; phase diagrams for simple and multi-component gases; the thermal conductivity; and the kinetics of hydrate dissociation. The final chapter evaluates the net energy balance of recovering hydrates and shows that a substantial positive energy balance can theoretically be achieved. The Appendices of the Handbook summarize physical and thermodynamic properties of gases, liquids and solids that can be used in designing and evaluating recovery processes of hydrates. 158 references, 67 figures, 47 tables.

  17. Gas hydrate formation rates from dissolved-phase methane in porous laboratory specimens (United States)

    Waite, William F.; Spangenberg, E.K.


    Marine sands highly saturated with gas hydrates are potential energy resources, likely forming from methane dissolved in pore water. Laboratory fabrication of gas hydrate-bearing sands formed from dissolved-phase methane usually requires 1–2 months to attain the high hydrate saturations characteristic of naturally occurring energy resource targets. A series of gas hydrate formation tests, in which methane-supersaturated water circulates through 100, 240, and 200,000 cm3 vessels containing glass beads or unconsolidated sand, show that the rate-limiting step is dissolving gaseous-phase methane into the circulating water to form methane-supersaturated fluid. This implies that laboratory and natural hydrate formation rates are primarily limited by methane availability. Developing effective techniques for dissolving gaseous methane into water will increase formation rates above our observed (1 ± 0.5) × 10−7 mol of methane consumed for hydrate formation per minute per cubic centimeter of pore space, which corresponds to a hydrate saturation increase of 2 ± 1% per day, regardless of specimen size.

  18. Prediction of Superconductivity in 3d Transition-Metal Based Antiperovskites via Magnetic Phase Diagram (United States)

    Shao, Dingfu; Lu, Wenjian; Tong, Peng; Lin, Shuai; Lin, Jianchao; Sun, Yuping


    We theoretically studied the electronic structure, magnetic properties, and lattice dynamics of a series of 3d transition-metal antiperovskite compounds AXM3 by density function theory. Based on the Stoner criterion, we drew the magnetic phase diagram of carbon-based antiperovskites ACM3. In the phase diagram, compounds with non-magnetic ground state but locating near the ferromagnetic boundary are suggested to have high N(EF) that may cause sizeable electron-phonon coupling and make the compounds superconducting. To approve this deduction, we systematically calculated the phonon spectra and electron-phonon coupling of a series of Cr-based antiperovskites ACCr3 and ANCr3. The results show that AlCCr3, GaCCr3, and ZnNCr3 could be moderate coupling BCS superconductors. The influence of spin fluctuation on superconductivity are discussed. Furthermore, other potential superconducting AXM3 including some new Co- and Fe-based antiperovskite superconductors are predicted from the magnetic phase diagram.

  19. Gold-copper nano-alloy, "Tumbaga", in the era of nano: phase diagram and segregation. (United States)

    Guisbiers, Grégory; Mejia-Rosales, Sergio; Khanal, Subarna; Ruiz-Zepeda, Francisco; Whetten, Robert L; José-Yacaman, Miguel


    Gold-copper (Au-Cu) phases were employed already by pre-Columbian civilizations, essentially in decorative arts, whereas nowadays, they emerge in nanotechnology as an important catalyst. The knowledge of the phase diagram is critical to understanding the performance of a material. However, experimental determination of nanophase diagrams is rare because calorimetry remains quite challenging at the nanoscale; theoretical investigations, therefore, are welcomed. Using nanothermodynamics, this paper presents the phase diagrams of various polyhedral nanoparticles (tetrahedron, cube, octahedron, decahedron, dodecahedron, rhombic dodecahedron, truncated octahedron, cuboctahedron, and icosahedron) at sizes 4 and 10 nm. One finds, for all the shapes investigated, that the congruent melting point of these nanoparticles is shifted with respect to both size and composition (copper enrichment). Segregation reveals a gold enrichment at the surface, leading to a kind of core-shell structure, reminiscent of the historical artifacts. Finally, the most stable structures were determined to be the dodecahedron, truncated octahedron, and icosahedron with a Cu-rich core/Au-rich surface. The results of the thermodynamic approach are compared and supported by molecular-dynamics simulations and by electron-microscopy (EDX) observations.

  20. Dark energy in six nearby galaxy flows: Synthetic phase diagrams and self-similarity (United States)

    Chernin, A. D.; Teerikorpi, P.; Dolgachev, V. P.; Kanter, A. A.; Domozhilova, L. M.; Valtonen, M. J.; Byrd, G. G.


    Outward flows of galaxies are observed around groups of galaxies on spatial scales of about 1 Mpc, and around galaxy clusters on scales of 10 Mpc. Using recent data from the Hubble Space Telescope (HST), we have constructed two synthetic velocity-distance phase diagrams: one for four flows on galaxy-group scales and the other for two flows on cluster scales. It has been shown that, in both cases, the antigravity produced by the cosmic dark-energy background is stronger than the gravity produced by the matter in the outflow volume. The antigravity accelerates the flows and introduces a phase attractor that is common to all scales, corresponding to a linear velocity-distance relation (the local Hubble law). As a result, the bundle of outflow trajectories mostly follow the trajectory of the attractor. A comparison of the two diagrams reveals the universal self-similar nature of the outflows: their gross phase structure in dimensionless variables is essentially independent of their physical spatial scales, which differ by approximately a factor of 10 in the two diagrams.

  1. Identification of the hydrate gel phases present in phosphate-modified calcium aluminate binders

    Energy Technology Data Exchange (ETDEWEB)

    Chavda, Mehul A.; Bernal, Susan A. [Department of Materials Science and Engineering, The University of Sheffield, Sheffield S1 3JD (United Kingdom); Apperley, David C. [Solid-State NMR Group, Department of Chemistry, Durham University, Durham DH1 3LE (United Kingdom); Kinoshita, Hajime [Department of Materials Science and Engineering, The University of Sheffield, Sheffield S1 3JD (United Kingdom); Provis, John L., E-mail: [Department of Materials Science and Engineering, The University of Sheffield, Sheffield S1 3JD (United Kingdom)


    The conversion of hexagonal calcium aluminate hydrates to cubic phases in hydrated calcium aluminate cements (CAC) can involve undesirable porosity changes and loss of strength. Modification of CAC by phosphate addition avoids conversion, by altering the nature of the reaction products, yielding a stable amorphous gel instead of the usual crystalline hydrate products. Here, details of the environments of aluminium and phosphorus in this gel were elucidated using solid-state NMR and complementary techniques. Aluminium is identified in both octahedral and tetrahedral coordination states, and phosphorus is present in hydrous environments with varying, but mostly low, degrees of crosslinking. A {sup 31}P/{sup 27}Al rotational echo adiabatic passage double resonance (REAPDOR) experiment showed the existence of aluminium–phosphorus interactions, confirming the formation of a hydrated calcium aluminophosphate gel as a key component of the binding phase. This resolves previous disagreements in the literature regarding the nature of the disordered products forming in this system.

  2. Uhlenbeck-Ford model: Phase diagram and corresponding-states analysis (United States)

    Paula Leite, Rodolfo; Santos-Flórez, Pedro Antonio; de Koning, Maurice


    Using molecular dynamics simulations and nonequilibrium thermodynamic-integration techniques we compute the Helmholtz free energies of the body-centered-cubic (bcc), face-centered-cubic (fcc), hexagonal close-packed, and fluid phases of the Uhlenbeck-Ford model (UFM) and use the results to construct its phase diagram. The pair interaction associated with the UFM is characterized by an ultrasoft, purely repulsive pair potential that diverges logarithmically at the origin. We find that the bcc and fcc are the only thermodynamically stable crystalline phases in the phase diagram. Furthermore, we report the existence of two reentrant transition sequences as a function of the number density, one featuring a fluid-bcc-fluid succession and another displaying a bcc-fcc-bcc sequence near the triple point. We find strong resemblances to the phase behavior of other soft, purely repulsive systems such as the Gaussian-core model (GCM), inverse-power-law, and Yukawa potentials. In particular, we find that the fcc-bcc-fluid triple point and the phase boundaries in its vicinity are in good agreement with the prediction supplied by a recently proposed corresponding-states principle [J. Chem. Phys. 134, 241101 (2011), 10.1063/1.3605659; Europhys. Lett. 100, 66004 (2012), 10.1209/0295-5075/100/66004]. The particularly strong resemblance between the behavior of the UFM and GCM models are also discussed.

  3. Experimental investigation and thermodynamic calculations of the Bi–In–Ni phase diagram

    Energy Technology Data Exchange (ETDEWEB)

    Premović, Milena [University in Priština, Faculty of Technical Science, Kosovo, Mitrovica (Serbia); Minić, Duško, E-mail: [University in Priština, Faculty of Technical Science, Kosovo, Mitrovica (Serbia); Manasijević, Dragan [University of Belgrade, Technical Faculty, Bor (Serbia); Ćosović, Vladan [University of Belgrade, Institute of Chemistry, Technology and Metallurgy, Belgrade (Serbia); Živković, Dragana [University of Belgrade, Technical Faculty, Bor (Serbia); Dervišević, Irma [University in Priština, Faculty of Technical Science, Kosovo, Mitrovica (Serbia)


    Highlights: • Calculated constitutive binary system based on literature data. • Experimentally determined (DTA) temperatures of phase transformations compared with analytical calculation. • Definition of several vertical sections. • Calculated horizontal section, confirmed by experimental SEM–EDS and XRD method. • Calculated liquidus surface projection and determined invariant reaction occurred in ternary Bi–In–Ni system. - Abstract: Phase diagram of the Bi–In–Ni ternary system was investigated using differential thermal analysis (DTA), scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS), and X-ray powder diffraction (XRD) analysis. Experimentally obtained results were compared with the results of thermodynamic calculation of phase equilibria based on calculation of phase diagram (CALPHAD) method and literature data. Phase transition temperatures of alloys with overall compositions along three selected vertical sections In–Bi{sub 0.8}Ni{sub 0.2}, x(Bi) = 0.6 and Bi–In{sub 0.5}Ni{sub 0.5} were measured by DTA. Liquidus temperatures were experimentally determined and compared with the results of thermodynamic calculation. Identification of coexisting phases in samples equilibrated at 100 °C, 300 °C and 350 °C was carried out using SEM–EDS and XRD methods. The obtained results were compared with the calculated isothermal sections of the Bi–In–Ni ternary system at corresponding temperatures. Calculated liquidus projection and invariant equilibria of the Bi–In–Ni ternary system were presented.

  4. Cluster Mean-Field Approach to the Steady-State Phase Diagram of Dissipative Spin Systems

    Directory of Open Access Journals (Sweden)

    Jiasen Jin


    Full Text Available We show that short-range correlations have a dramatic impact on the steady-state phase diagram of quantum driven-dissipative systems. This effect, never observed in equilibrium, follows from the fact that ordering in the steady state is of dynamical origin, and is established only at very long times, whereas in thermodynamic equilibrium it arises from the properties of the (free energy. To this end, by combining the cluster methods extensively used in equilibrium phase transitions to quantum trajectories and tensor-network techniques, we extend them to nonequilibrium phase transitions in dissipative many-body systems. We analyze in detail a model of spin-1/2 on a lattice interacting through an XYZ Hamiltonian, each of them coupled to an independent environment that induces incoherent spin flips. In the steady-state phase diagram derived from our cluster approach, the location of the phase boundaries and even its topology radically change, introducing reentrance of the paramagnetic phase as compared to the single-site mean field where correlations are neglected. Furthermore, a stability analysis of the cluster mean field indicates a susceptibility towards a possible incommensurate ordering, not present if short-range correlations are ignored.

  5. Fabrication of Colloidal Laves Phases via Hard Tetramers and Hard Spheres: Bulk Phase Diagram and Sedimentation Behavior (United States)


    Colloidal photonic crystals display peculiar optical properties that make them particularly suitable for application in different fields. However, the low packing fraction of the targeted structures usually poses a real challenge in the fabrication stage. Here, we propose a route to colloidal photonic crystals via a binary mixture of hard tetramers and hard spheres. By combining theory and computer simulations, we calculate the phase diagram as well as the stacking diagram of the mixture and show that a colloidal analogue of the MgCu2 Laves phase—which can serve as a precursor of a photonic band-gap structure—is a thermodynamically stable phase in a large region of the phase diagram. Our findings show a relatively large coexistence region between the fluid and the Laves phase, which is potentially accessible by experiments. Furthermore, we determine the sedimentation behavior of the suggested mixture, by identifying several stacking sequences in the sediment. Our work uncovers a self-assembly path toward a photonic structure with a band gap in the visible region. PMID:28787126

  6. Development of PEX explosives phase diagram studies. Quarterly report, October--December, 1971

    Energy Technology Data Exchange (ETDEWEB)

    Faubion, B.D.


    Experiments have been carried out to determine the solid-liquid phase diagrams of binary mixtures of FEFO, EDNP, BDNPA and BDNPF. Cooling curves for the mixtures give no indication of crystal formation. Penetration measurements indicate a glass transition for all of the mixtures below {minus}40 C. The existence of glassy states for the mixtures was confirmed by visual observation with a polarizing microscope. Thermomicroscopy has been used in the preliminary study of the phase behavior of four binary mixtures. So far no eutectic has been observed.

  7. Phase diagram and dynamic response functions of the Holstein-Hubbard model

    Energy Technology Data Exchange (ETDEWEB)

    Koller, W. [Department of Mathematics, Imperial College, 180 Queen' s Gate, London SW7 2AZ (United Kingdom); Meyer, D. [Department of Mathematics, Imperial College, 180 Queen' s Gate, London SW7 2AZ (United Kingdom)]. E-mail:; Hewson, A.C. [Department of Mathematics, Imperial College, 180 Queen' s Gate, London SW7 2AZ (United Kingdom); O-bar no, Y. [Department of Physics, Niigata University, Ikarashi, Niigata 950-2181 (Japan)


    We present the phase diagram and dynamical correlation functions for the Holstein-Hubbard model at half-filling and at zero temperature. The calculations are based on the dynamical mean field theory (DMFT). The effective impurity model is solved using exact diagonalization (ED) and the numerical renormalization group (NRG). Excluding long-range order, we find three different paramagnetic phases, metallic, bipolaronic and Mott insulating, depending on the Hubbard interaction U and the electron-phonon coupling g. We present the behaviour of the one-electron spectral functions and phonon spectra close to the metal-insulator transitions.

  8. Tuning the phase diagrams: the miscibility studies of multilactate liquid crystalline compounds

    Czech Academy of Sciences Publication Activity Database

    Bubnov, Alexej; Tykarska, M.; Hamplová, Věra; Kurp, K.


    Roč. 89, č. 9 (2016), s. 885-893 ISSN 0141-1594 R&D Projects: GA ČR GA13-14133S; GA MŠk(CZ) LD14007; GA ČR GA15-02843S Grant - others:EU - ICT(XE) COST Action IC1208 Institutional support: RVO:68378271 Keywords : miscibility study * binary mixture * polar smectic phase * lactic acid derivative * miscibility study * phase diagram * self-assembling behaviour Subject RIV: JJ - Other Materials Impact factor: 1.060, year: 2016

  9. Energetics and phase diagrams of Fe-Cr and Co-Cr systems from first principles

    Directory of Open Access Journals (Sweden)

    Vreštzál J.


    Full Text Available The first principles computations of the total energies of complex phases have been addressed recently. The structural energy differences, calculated by FLAPW (Full potential augmented plane wave method, enable us to utilize a more complete physical information about total energy of intermetallic phases and to propose a new model for their thermodynamic description. Our approach is based on the two-sublattice model, similarly as for solid solution phases, but the structural energy differences for end-members in the metastable or unstable structures are obtained by means of first-principles electronic structure calculations. Phase diagrams of Fe-Cr and Co-Cr systems containing the intermetallic sigma-phase (5 inequivalent lattice sites, 30 atoms in repeat cell are described here as an example of application of our new model.

  10. Phase Equilibria of H2SO4, HNO3, and HCl Hydrates and the Composition of Polar Stratospheric Clouds (United States)

    Wooldridge, Paul J.; Zhang, Renyi; Molina, Mario J.


    Thermodynamic properties and phase equilibria behavior for the hydrates and coexisting pairs of hydrates of common acids which exist in the stratosphere are assembled from new laboratory measurements and standard literature data. The analysis focuses upon solid-vapor and solid-solid-vapor equilibria at temperatures around 200 K and includes new calorimetric and vapor pressure data. Calculated partial pressures versus 1/T slopes for the hydrates and coexisting hydrates agree well with experimental data where available.

  11. Phase diagram of interacting spinless fermions on the honeycomb lattice: A comprehensive exact diagonalization study (United States)

    Capponi, Sylvain; Läuchli, Andreas M.


    We investigate the phase diagram of spinless fermions with nearest- and next-nearest-neighbor density-density interactions on the honeycomb lattice at half-filling. Using exact diagonalization techniques of the full Hamiltonian and constrained subspaces, combined with a careful choice of finite-size clusters, we determine the different charge orderings that occur for large interactions. In this regime, we find a two-sublattice Néel-like state, a charge modulated state with a tripling of the unit cell, a zigzag phase, and a charge ordered state with a 12-site unit cell we call Néel domain wall crystal, as well as a region of phase separation for attractive interactions. A sizable region of the phase diagram is classically degenerate, but it remains unclear whether an order-by-disorder mechanism will lift the degeneracy. For intermediate repulsion, we find evidence for a Kekulé or plaquette bond-order wave phase. We also investigate the possibility of a spontaneous Chern insulator phase (dubbed topological Mott insulator), as previously put forward by several mean-field studies. Although we are unable to detect convincing evidence for this phase based on energy spectra and order parameters, we find an enhancement of current-current correlations with the expected spatial structure compared to the noninteracting situation. While for the studied t -V1-V2 model, the phase transition to the putative topological Mott insulator is preempted by the phase transitions to the various ordered states, our findings might hint at the possibility for a topological Mott insulator in an enlarged Hamiltonian parameter space, where the competing phases are suppressed.

  12. A combined QXRD/TG method to quantify the phase composition of hydrated Portland cements

    Energy Technology Data Exchange (ETDEWEB)

    Soin, Alexander V.; Catalan, Lionel J.J. [Department of Chemical Engineering, Lakehead University, 955 Oliver Road, Thunder Bay, Ontario P7B 5E1 (Canada); Kinrade, Stephen D., E-mail: [Department of Chemistry, Lakehead University, 955 Oliver Road, Thunder Bay, Ontario P7B 5E1 (Canada)


    A new method is reported for quantifying the mineral phases in hydrated cement pastes that is based on a combination of quantitative X-ray diffractometry (QXRD) and thermogravimetry (TG). It differs from previous methods in that it gives a precise measure of the amorphous phase content without relying on an assumed stoichiometric relationship between the principal hydration products, calcium hydroxide (CH) and calcium silicate hydrate (C–S–H). The method was successfully applied to gray and white ordinary Portland cements (GOPC and WOPC, respectively) that were cured for up to 56 days. Phase distributions determined by QXRD/TG closely matched those from gray-level analysis of backscattered scanning electron microscope (BSEM) images, whereas elemental compositions obtained for the amorphous phase by QXRD/TG agreed well with those measured by quantitative energy dispersive X-ray spectroscopy (EDS)

  13. Phase diagram and quantum criticality of disordered Majorana-Weyl fermions (United States)

    Wilson, Justin; Pixley, Jed; Goswami, Pallab

    A three-dimensional px + ipy superconductor hosts gapless Bogoliubov-de Gennes (BdG) quasiparticles which provide an intriguing example of a thermal Hall semimetal (ThSM) phase of Majorana-Weyl fermions. We study the effect of quenched disorder on such a topological phase with both numerical and analytical methods. Using the kernel polynomial method, we compute the average and typical density of states for the BdG quasiparticles; based on this, we construct the disordered phase diagram. We show for infinitesimal disorder, the ThSM is converted into a diffusive thermal Hall metal (ThDM) due to rare statistical fluctuations. Consequently, the phase diagram of the disordered model only consists of ThDM and thermal insulating phases. Nonetheless, there is a cross-over at finite energies from a ThSM regime to a ThDM regime, and we establish the scaling properties of the avoided quantum critical point which marks this cross-over. Additionally, we show the existence of two types of thermal insulators: (i) a trivial thermal band insulator (ThBI), and (ii) a thermal Anderson insulator (AI). We also discuss the experimental relevance of our results for three-dimensional, time reversal symmetry breaking, triplet superconducting states.


    Energy Technology Data Exchange (ETDEWEB)

    Halavanau, A. [Fermilab; Ha, G. [POSTECH


    Intercepting multi-aperture masks (e.g. pepper pot or multislit mask) combined with a downstream transversedensity diagnostics (e.g. based on optical transition radiation or employing scintillating media) are commonly used for characterizing the phase space of charged particle beams and the associated emittances. The required data analysis relies on precise calculation of the RMS sizes and positions of the beamlets originated from the mask which drifted up to the analyzing diagnostics. Voronoi diagram is an efficient method for splitting a plane into subsets according to the distances between given vortices. The application of the method to analyze data from pepper pot and multislit mask based measurement is validated via numerical simulation and applied to experimental data acquired at the Argonne Wakefield Accelerator (AWA) facility. We also discuss the application of the Voronoi diagrams to quantify transverselymodulated beams distortion.

  15. Salt hydrates and other phase-change materials

    Energy Technology Data Exchange (ETDEWEB)

    Cantor, S.


    The objectives of the project are: to ascertain thermal performance of Na/sub 2/SO/sub 4/ . 10H/sub 2/O and other incongruently melting salt hydrates by calorimetric investigation of melting and freezing; and select compounds and mixtures suitable for isothermal heat storage within the range, 90 to 250/sup 0/C. Selection is to be used on laboratory evaluation as well as on economic and technical screening criteria.

  16. Global Phase Diagram of a Three-Dimensional Dirty Topological Superconductor. (United States)

    Roy, Bitan; Alavirad, Yahya; Sau, Jay D


    We investigate the phase diagram of a three-dimensional, time-reversal symmetric topological superconductor in the presence of charge impurities and random s-wave pairing. Combining complimentary field theoretic and numerical methods, we show that the quantum phase transition between two topologically distinct paired states (or thermal insulators), described by thermal Dirac semimetal, remains unaffected in the presence of sufficiently weak generic randomness. At stronger disorder, however, these two phases are separated by an intervening thermal metallic phase of diffusive Majorana fermions. We show that across the insulator-insulator and metal-insulator transitions, normalized thermal conductance displays single parameter scaling, allowing us to numerically extract the critical exponents across them. The pertinence of our study in strong spin-orbit coupled, three-dimensional doped narrow gap semiconductors, such as Cu_{x}Bi_{2}Se_{3}, is discussed.

  17. Variation of the strange-quark chemical potential in the phase diagram of nuclear matter

    CERN Document Server

    Panagiotou, A D; Gerodimou, E


    On the basis of lattice calculations, we require the existence of a deconfined quark matter region (0phase, which goes asymptotically into the ideal quark-gluon plasma domain, in the phase diagram of nuclear matter. We consider empirically the dynamics of this region in terms of the order parameters and mass-scaled partition functions and derive an EoS. Then, the strange-quark chemical potential is expressed in a functional form of the temperature and light-quark chemical potential and its variation throughout the 3-region phase diagram is studied. We propose the change of the sign of the strange-quark chemical potential, from positive in the hadronic region to negative beyond, to be a unique, concise and well-defined indication of the quark- deconfinement phase transition in nuclear matter. Analysis of the nucleus-nucleus collision data from AGS and SPS is presented giving strong support to our proposal. (23 refs).

  18. Phase diagram in two-dimensional Hubbard model: variational cluster approximation (United States)

    Kocharian, Armen; Fang, Kun; Fernando, Gayanath; Balatsky, Alexander; Palandage, Kalum


    The Variational Cluster Approximation (VCA) is used to rigorously calculate the intrinsic phase diagram in bipartite two-dimensional (2d) Hubbard structures such as square and honeycomb lattice geometries with attraction and repulsion of electrons. The Mott-Hubbard gap, manifested as a smooth metal-insulator transition at finite U > 0 in both square and honeycomb lattices at half filling (n = 1), is in agreement with the generic 2d phase diagram. However, a density variation with the chemical potential displays their distinct structural differences away from half filling. Near n = 1 at equilibrium we found discontinuous transition in square lattices signaling a phase separation instability into an inhomogeneous state with hole rich (metallic) and hole poor (n = 1 -insulating) regions. In contrast, a smooth density transition in honeycomb geometry describes a continuous evolution of homogenous (metallic) state. Incorporation of long-range input in VCA using U >0 and U topological insulators as well as comparison to other studies is discussed. The VCA provides strong support for spontaneous phase separation instability found in our quantum cluster calculations. The authors acknowledge the BNL and LANL computing facilities supported by the U.S. DOE, Office of Basic Energy Sciences, under Contracts No.DE-AC02-98CH10886, No.DE-AC52-06NA25396 and Sandia National Laboratories (Contract DE-AC04-94AL85000).

  19. Hydration Characteristics of Tetracalcium Alumino-Ferrite Phase in the presence Calcium Carbonate

    Directory of Open Access Journals (Sweden)

    M. M. Radwan


    Full Text Available Tetracalcium alumino-ferrite phase (C4AF prepared from pure starting materials was employed for composing various mixes prepared of C4AF phase, CaSO4·2H2O, Ca(OH2 and CaCO3. The effect of replacing calcium sulphate (gypsum by calcium carbonate as a set retarder on the hydration behaviour of ferrite phase was studied. The mixes were hydrated for various periods and the hydration products were investigated using the appropriate techniques. The kinetics of hydration was studied by measuring the chemically-combined water as well as the combined lime contents. The mineralogical constitution was studied by using XRD, and DTA. The microstructure of some represented hydrated samples was investigated by scanning electron microscopy. Some interesting conclusions have been drawn. It was found that calcium carbonate reacts with tetracalcium alumino-ferrite phase (C4AF in the presence of hydrolime [Ca(OH2] to form carboferrite compounds which may coat the aluminate grains as ettringite does and this may probably regulate the setting time.

  20. Thermodynamic Calculations of Ternary Polyalcohol and Amine Phase Diagrams for Thermal Energy Storage Materials (United States)

    Shi, Renhai

    Organic polyalcohol and amine globular molecular crystal materials as phase change materials (PCMs) such as Pentaglycerine (PG-(CH3)C(CH 2OH)3), Tris(hydroxymethyl)aminomethane (TRIS-(NH2)C(CH 2OH)3), 2-amino-2methyl-1,3-propanediol (AMPL-(NH2)(CH3)C(CH2OH)2), and neopentylglycol (NPG-(CH3)2C(CH2OH) 2) can be considered to be potential candidates for thermal energy storage (TES) applications such as waste heat recovery, solar energy utilization, energy saving in buildings, and electronic device management during heating or cooling process in which the latent heat and sensible heat can be reversibly stored or released through solid state phase transitions over a range of temperatures. In order to understand the polymorphism of phase transition of these organic materials and provide more choice of materials design for TES, binary systems have been studied to lower the temperature of solid-state phase transition for the specific application. To our best knowledge, the study of ternary systems in these organic materials is limited. Based on this motivation, four ternary systems of PG-TRIS-AMPL, PG-TRIS-NPG, PG-AMPL-NPG, and TRIS-AMPL-NPG are proposed in this dissertation. Firstly, thermodynamic assessment with CALPHAD method is used to construct the Gibbs energy functions into thermodynamic database for these four materials based on available experimental results from X-Ray Diffraction (XRD) and Differential Scanning Calorimetry (DSC). The phase stability and thermodynamic characteristics of these four materials calculated from present thermodynamic database with CALPHAD method can match well the present experimental results from XRD and DSC. Secondly, related six binary phase diagrams of PG-TRIS, PG-AMPL, PG-NPG, TRIS-AMPL, TRIS-NPG, and AMPL-NPG are optimized with CALPHAD method in Thermo-Calc software based on available experimental results, in which the substitutional model is used and excess Gibbs energy is expressed with Redlich-Kister formalism. The

  1. Thermodynamics at the nanoscale: phase diagrams of nickel-carbon nanoclusters and equilibrium constants for phase transitions. (United States)

    Engelmann, Yannick; Bogaerts, Annemie; Neyts, Erik C


    Using reactive molecular dynamics simulations, the melting behavior of nickel-carbon nanoclusters is examined. The phase diagrams of icosahedral and Wulff polyhedron clusters are determined using both the Lindemann index and the potential energy. Formulae are derived for calculating the equilibrium constants and the solid and liquid fractions during a phase transition, allowing more rational determination of the melting temperature with respect to the arbitrary Lindemann value. These results give more insight into the properties of nickel-carbon nanoclusters in general and can specifically be very useful for a better understanding of the synthesis of carbon nanotubes using the catalytic chemical vapor deposition method.

  2. Pb–Te–O phase equilibrium diagram and the lead telluride thermal oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Berchenko, Nicolas, E-mail: [Centre of Microelectronics and Nanotechnology, Rzeszow University, Rejtana 16A, Rzeszow 35-959 Poland (Poland); Fadeev, Sergey, E-mail: [Lviv Ivan Franko National University, Dragomanov st., 50, Lviv 79005 (Ukraine); Savchyn, Volodymyr, E-mail: [Lviv Polytechnic State University, Bandera st., 12, Lviv 79646 (Ukraine); Kurbanov, Kurban, E-mail: [Kremenchuk Flight College of National Aviation University, 17/6 Peremogy Street, Kremenchuk, Poltava region 39600 (Ukraine); Trzyna, Malgorzata, E-mail: [Centre of Microelectronics and Nanotechnology, Rzeszow University, Rejtana 16A, Rzeszow 35-959 Poland (Poland); Cebulski, Jozef, E-mail: [Center for Innovation and Transfer of Natural Sciences and Engineering Knowledge, Rzeszow University, Rejtana 16A, Rzeszow 35-959 Poland (Poland)


    Highlights: • Pb–Te–O diagram can correctly predict oxidation products in a wide range of temperatures. • Account for temperature change of Gibbs energies is necessary for correct evaluation of oxidation. • The main product of PbTe oxidation at temperatures < 673 K is PbTeO{sub 3}. • TOF SIMS detects the presence of ternary oxides at PbTe surface at 293 K. • Products of PbTe oxidation are significantly changed at temperatures above 673 K. - Abstract: To clarify the behavior of thermally oxidized PbTe the phase equilibrium diagram was calculated taking into account the change of the standard Gibbs energies of formation with the temperature up to 873 K. The X-ray diffractometry (XRD) studies of thermally oxidized PbTe are, summarized. In good agreement with XRD studies the Pb–Te–O diagram predicts the formation of the lead tellurite PbTeO{sub 3} at the relatively low temperatures (<673 K). At higher temperatures (>673 K) it predicts the formation of other ternary PbTe oxides (Pb{sub 3}TeO{sub 5}, Pb{sub 5}TeO{sub 7}, and Pb{sub 2}TeO{sub 4}) detected in PbTe sintered material at high-temperature oxidation. This must be considered when choosing a method of preparing the nanostructured PbTe composites and when analyzing their properties. This should be considered when choosing processing techniques structured material.

  3. Electrochemical phase diagrams of Ni from ab initio simulations: role of exchange interactions on accuracy (United States)

    Huang, Liang-Feng; Rondinelli, James M.


    The stabilities of Ni metal and its derived compounds, including oxides, hydroxides, and oxyhydroxides under electrochemical conditions, can be readily predicted from the Ni Pourbaix diagram, where the formation free energies of the involved species are utilized to construct the phase stability map with respect to electrode potential and pH. We calculate and analyze the crystal structures, electronic structures, and thermodynamic energies of Ni metal and its compounds using different exchange-correlation functionals to density-functional-theory (DFT), including the semilocal LDA and GGA density functionals, the nonlocal metaGGA, and the hybrid density functionals. Next, we simulate the corresponding Ni Pourbaix diagrams to compare systematically the performance of the functional to each other and to experimental observations. We show that the structures and energies obtained from experimental databases may not be sufficiently accurate to describe direct electrochemical observations, and we explain how the electronic exchange within the density functionals plays a key role in determining the accuracy of the DFT calculated electronic, thermodynamic, and electrochemical properties. We find that only the hybrid density functional produces reliable results owing to the fractional contribution of exact Fock exchange included therein. Last, based on our accurate Ni Pourbaix diagram, we construct band-gap and magnetic electrochemical maps which can facilitate more experimental measurements and property assessments under variable potential and pH in the future.

  4. Calcium silicate hydrates: Solid and liquid phase composition


    Lothenbach Barbara; Nonat André


    © 2015 Elsevier Ltd. This paper presents a review on the relationship between the composition the structure and the solution in which calcium silicate hydrate (C S H) is equilibrated. The silica chain length in C S H increases with the silicon concentration and the calcium content in the interlayer space with the calcium concentrations. Sodium and potassium are taken up in the interlayer space preferentially at low calcium concentrations and thus by low Ca/Si C S H. Aluminium uptake in C S H ...

  5. Phase diagram of the three states Potts model with next nearest neighbour interactions on the Bethe lattice

    Energy Technology Data Exchange (ETDEWEB)

    Ganikhodjaev, Nasir [Faculty of Science, IIUM, 25200 Kuantan (Malaysia); Institute of Mathematics and Information Technology, 100125 Tashkent (Uzbekistan); Mukhamedov, Farrukh [Faculty of Science, IIUM, 25200 Kuantan (Malaysia); Pah, Chin Hee [Faculty of Science, IIUM, 25200 Kuantan (Malaysia)], E-mail:


    We have found an exact phase diagram of the Potts model with competing nearest neighbor and next nearest neighbor interactions on the Bethe lattice of order two. The diagram consists of five phases: ferromagnetic, paramagnetic, modulated, antiphase and paramodulated, all meeting at the multicritical point (T=0,p=1/3). We report on a new phase which we denote as paramodulated, found at low temperatures and characterized by zero average magnetization lying inside the modulated phase. Such a phase, inherent in the Potts model has no analogues in the Ising setting.

  6. Thermochemical and phase diagram studies of the Bi-Ni-Sn system

    Energy Technology Data Exchange (ETDEWEB)

    Milcheva, N. [Faculty of Chemistry, University of Plovdiv, 24 Tsar Asen str., 4000 Plovdiv (Bulgaria); Broz, P. [Masaryk University, Faculty of Science, Kotlarska 2, 61137 Brno (Czech Republic); Masaryk University, Central European Institute of Technology, CEITEC, Kamenice 753/5, 625 00, Brno (Czech Republic); Bursik, J. [Institute of Physics of Materials, Academy of Sciences, Zizkova 22, 61662 Brno (Czech Republic); Vassilev, G.P., E-mail: [Faculty of Chemistry, University of Plovdiv, 24 Tsar Asen str., 4000 Plovdiv (Bulgaria)


    Highlights: Black-Right-Pointing-Pointer We study the phase diagram Bi-Ni-Sn by using scanning electron microscopy and differential scanning calorimetry. Black-Right-Pointing-Pointer The samples are positioned in 3 isopleths with constant Ni contents of 0.05, 0.10 and 0.15 mol fraction. Black-Right-Pointing-Pointer It has been confirmed that a ternary eutectic reaction appears at around 116-129 Degree-Sign C. Black-Right-Pointing-Pointer Experimental liquidus temperatures were obtained and compared to calculated ones. Black-Right-Pointing-Pointer Six groups of thermal arrests were registered (except the eutectic and liquidus related peaks). - Abstract: The phase diagram Bi-Ni-Sn was studied by means of SEM (scanning electron microscopy)/EDS (energy-dispersive solid state spectrometry), by DSC (differential scanning calorimetry) and RT-XRD (room temperature X-Ray diffraction) in order to attain more information about this ternary phase diagram. The samples were positioned in three isopleths with nickel contents of: 0.05 (section 1), 0.10 (section 2) and 0.15 (section 3) mole fractions, respectively. The mole fractions of Sn corresponding to the particular sections were as follows: from 0.19 to 0.76 (section 1), from 0.18 to 0.72 (section 2); from 0.17 to 0.68 (section 3). Mixtures of pure metals were sealed under vacuum in amorphous silica ampoules and annealed at 350 Degree-Sign C. A binary Bi-Sn eutectic sample was synthesized and used as internal standard. The existence of a previously reported ternary eutectic reaction was confirmed. Liquidus temperatures were identified and the results were compared to CALPHAD-type calculations. It was found that ternary samples' liquidus temperatures were higher than the calculated ones. Six more groups of thermal arrests were registered except the eutectic and liquidus related peaks.

  7. Phase diagram, thermodynamic investigations, and modelling of systems relevant to lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Fuertauer, Siegfried; Beutl, Alexander; Flanorfer, Hans [Vienna Univ. (Austria). Dept. of Inorganic Chemistry - Functional Materials; Li, Dajian; Cupid, Damian [Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen (Germany). Inst. for Applied Materials - Applied Materials Physics (IAM-AWP); Henriques, David; Giel, Hans; Markus, Thorsten [Mannheim Univ. of Applied Sciences (Germany). Inst. for Thermo- and Fluiddynamics


    This article reports on two consecutive joint projects titled ''Experimental Thermodynamics and Phase Relations of New Electrode Materials for Lithium-Ion Batteries'', which were performed in the framework of the WenDeLIB 1473 priority program ''Materials with new Design for Lithium Ion Batteries''. Hundreds of samples were synthesized using experimental techniques specifically developed to deal with highly reactive lithium and lithium-containing compounds to generate electrochemical, phase diagram and crystal structure data in the Cu-Li, Li-Sn, Li-Sb, Cu-Li-Sn, Cu-Li-Sb and selected oxide systems. The thermochemical and phase diagram data were subsequently used to develop self-consistent thermodynamic descriptions of several binary systems. In the present contribution, the experimental techniques, working procedures, results and their relevance to the development of new electrode materials for lithium ion batteries are discussed and summarized. The collaboration between the three groups has resulted in more than fifteen (15) published articles during the six-year funding period.

  8. Using Empirical Phase Diagrams to Understand the Role of Intramolecular Dynamics in Immunoglobulin G Stability (United States)

    Ramsey, Joshua D.; Gill, Michelle L.; Kamerzell, Tim J.; Price, E. Shane; Joshi, Sangeeta B.; Bishop, Steven M.; Oliver, Cynthia N.; Middaugh, C. Russell


    Understanding the relationship between protein dynamics and stability is of paramount importance to the fields of biology and pharmaceutics. Clarifying this relationship is complicated by the large amount of experimental data that must be generated and analyzed if motions that exist over the wide range of timescales are to be included. To address this issue, we propose an approach that utilizes a multidimensional vector-based empirical phase diagram (EPD) to analyze a set of dynamic results acquired across a temperature-pH perturbation plane. This approach is applied to a humanized immunoglobulin G1 (IgG1), a protein of major biological and pharmaceutical importance whose dynamic nature is linked to its multiple biological roles. Static and dynamic measurements are used to characterize the IgG and to construct both static and dynamic empirical phase diagrams. Between pH 5 and 8, a single, pH-dependent transition is observed that corresponds to thermal unfolding of the IgG. Under more acidic conditions, evidence exists for the formation of a more compact, aggregation resistant state of the immunoglobulin, known as A-form. The dynamics-based EPD presents a considerably more detailed pattern of apparent phase transitions over the temperature-pH plane. The utility and potential applications of this approach are discussed. PMID:19072858

  9. Magnetic Properties and Magnetic Phase Diagrams of Trigonal DyNi3Ga9 (United States)

    Ninomiya, Hiroki; Matsumoto, Yuji; Nakamura, Shota; Kono, Yohei; Kittaka, Shunichiro; Sakakibara, Toshiro; Inoue, Katsuya; Ohara, Shigeo


    We report the crystal structure, magnetic properties, and magnetic phase diagrams of single crystalline DyNi3Ga9 studied using X-ray diffraction, electrical resistivity, specific heat, and magnetization measurements. DyNi3Ga9 crystallizes in the chiral structure with space group R32. The dysprosium ions, which are responsible for the magnetism in this compound, form a two-dimensional honeycomb structure on a (0001) plane. We show that DyNi3Ga9 exhibits successive phase transitions at TN = 10 K and T'N = 9 K. The former suggests quadrupolar ordering, and the latter is attributed to the antiferromagnetic order. It is considered that DyNi3Ga9 forms the canted-antiferromagnetic structure below T'N owing to a small hysteresis loop of the low-field magnetization curve. We observe the strong easy-plane anisotropy, and the multiple-metamagnetic transitions with magnetization-plateaus under the field applied along the honeycomb plane. For Hallel [2\\bar{1}\\bar{1}0], the plateau-region arises every 1/6 for saturation magnetization. The magnetic phase diagrams of DyNi3Ga9 are determined for the fields along principal-crystal axes.

  10. Universal criterion and phase diagram for switching a magnetic vortex core in soft magnetic nanodots


    Lee, Ki-Suk; Kim, Sang-Koog; Yu, Young-Sang; Choi, Youn-Seok; Guslienko, Konstantin Yu.; Jung, Hyunsung; Fischer, Peter


    The universal criterion for ultrafast vortex-core switching between the up- and down-core bistates in soft magnetic nanodots was investigated by micromagnetic simulations along with analytical calculations. Vortex-core switching occurs whenever the velocity of vortex-core motion reaches the critical velocity that is expressed as (e.g. m/s for Permalloy), where Aex is the exchange stiffness, and is the gyromagnetic ratio. On the basis of the above results, phase diagrams for the vortex-core sw...

  11. Phase diagram for Bi1-xCaxMnO3 (x < 0.5) (United States)

    Qin, Yuhai; Tyson, Trevor; Cheong, Sang-Wook; Xu, Xiaonong


    The multiferroic BiMnO3 system, in which ferroelectronic and ferromagnetic orders can coexist, has attracted much research work in the past years for its potential technological applications. For the more general system Bi1-xCaxMnO3, the phase diagram for the Ca rich region (x > 0.4) has been established [1]. In order to understand the multiferroic behavior near the x=0 system, the hole-doped region (0Physical Review B: Condensed Matter and Materials Physics 63, 134412/1 (2001).

  12. Interdependent binary choices under social influence: Phase diagram for homogeneous unbiased populations (United States)

    Fernández del Río, Ana; Korutcheva, Elka; de la Rubia, Javier


    Coupled Ising models are studied in a discrete choice theory framework, where they can be understood to represent interdependent choice making processes for homogeneous populations under social influence. Two different coupling schemes are considered. The nonlocal or group interdependence model is used to study two interrelated groups making the same binary choice. The local or individual interdependence model represents a single group where agents make two binary choices which depend on each other. For both models, phase diagrams, and their implications in socioeconomic contexts, are described and compared in the absence of private deterministic utilities (zero opinion fields).

  13. Metal-Hydrogen Phase Diagrams in the Vicinity of Melting Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Shapovalov, V.I.


    Hydrogen-metal interaction phenomena belong to the most exciting challenges of today's physical metallurgy and physics of solids due to the uncommon behavior of hydrogen in condensed media and to the need for understanding hydrogen's strong negative impact on properties of some high-strength steels and.alloys. The paper cites and summarizes research data on fundamental thermodynamic characteristics of hydrogen in some metals that absorb it endothermally at elevated temperatures. For a number of metal-hydrogen systems, information on some phase diagrams previously not available to the English-speaking scientific community is presented.

  14. Interpretation of bent-crystal rocking curves using phase-space diagrams

    CERN Document Server

    Ren, B; Chapman, L D; Wu, X Y; Zhong, Z; Ivanov, I; Huang, X


    In developing a double bent-Laue crystal monochromator for synchrotron-based monochromatic computed tomography system, we applied a special projection of the phase-space diagram to interpret the shape of bent crystal rocking curves. Unlike the rigorous approach of the ray-tracing method, this graphical method provides direct pictures that allow checks of the physical significance of the shapes of the rocking curves, thereby providing quick guidelines for matching two bent crystals. The method's usefulness is demonstrated with our crexperimental results, and its limitations are discussed.

  15. Construction and Validation of Binary Phase Diagram for Amorphous Solid Dispersion Using Flory–Huggins Theory


    Bansal, Krishna; Baghel, Uttam Singh; Thakral, Seema


    Drug–polymer miscibility is one of the fundamental prerequisite for the successful design and development of amorphous solid dispersion formulation. The purpose of the present work is to provide an example of the theoretical estimation of drug–polymer miscibility and solubility on the basis of Flory–Huggins (F–H) theory and experimental validation of the phase diagram. The F–H interaction parameter, χd-p, of model system, aceclofenac and Soluplus, was estimated by two methods: by melting poin...

  16. The quark-gluon-plasma phase transition diagram, Hagedorn matter and quark-gluon liquid


    Zakout, Ismail; Greiner, Carsten


    In order to study the nuclear matter in the relativistic heavy ion collisions and the compact stars, we need the hadronic density of states for the entire ($\\mu_B-T$) phase transition diagram. We present a model for the continuous high-lying mass (and volume) spectrum density of states that fits the Hagedorn mass spectrum. This model explains the origin of the tri-critical point besides various phenomena such as the quarkyonic matter and the quark-gluon liquid. The Hagedorn mass spectrum is d...

  17. Phase diagrams for quantum Brownian motion on two-dimensional Bravais lattices (United States)

    Zhang, Grace H.


    We study quantum Brownian motion (QBM) models for a particle in a dissipative environment coupled to a periodic potential. We review QBM for a particle in a one-dimensional periodic potential and extend the study to that for a particle in two-dimensional (2D) periodic potentials of four Bravais lattice types: square, rectangular, triangular (hexagonal), and centered rectangular. We perform perturbative renormalization group analyses to derive the zero temperature flow diagrams and phase boundaries for a particle in these potentials, and observe localization behavior dependent on the anisotropy of the lattice parameters.

  18. Phase diagram of the AlVO{sub 4}-MoO{sub 3} system

    Energy Technology Data Exchange (ETDEWEB)

    Kurzawa, M.; Dabrowska, G. [Politechnika Szczecinska, Szczecin (Poland)


    The behaviour of MoO{sub 3} towards AlVO{sub 4} at temperatures up to 1000 C within the whole concentration range has been investigated by DTA and XRD. The results are presented in the form of a phase diagram. The AlVO{sub 4}-MoO{sub 3} system has been found to be a real two-component system only within the limits of the AlVO{sub 4}-AlVMoO{sub 7} subsolidus area. (author). 31 refs, 1 fig., 1 tab.

  19. Phase diagram of silicon using a DFT-based neural network potential (United States)

    Andreussi, Oliviero; Behler, Joerg; Parrinello, Michele


    The phase diagram of silicon is computed by means of Classical Molecular Dynamics. A recently developed [Behler and Parrinello, Phys. Rev. Lett. 98 146401 (2007)] neural-network potential based on Density Functional Theory calculations in the Local Density Approximation is used. This potential was shown to be several orders of magnitude faster than corresponding LDA-DFT calculations, while the accuracy is essentially maintained. Results on the liquid-solid coexistence curve are in good agreement with ab-initio calculations and demonstrate the quality of the neural-network potential.

  20. Phase Diagram of Symmetric Two-Dimensional Traffic Model II. Higher-Velocity Case (United States)

    Fukui, Minoru; Ishibashi, Yoshihiro


    The phase diagram for a symmetric two-dimensional traffic system with cars moving with a maximum velocity of 2 (a kind of the extended Biham-Middleton-Levine model) is studied. It turns out that the critical car density giving rise to the complete stop transition can be well fitted by the formula previously proposed for the flow in the jam flow phase. A notable discrepancy between the velocities obtained by cellular automaton simulations and from the formula is found in the high-velocity range in the jam flow phase. The discrepancy is attributed to the probabilistic nature of the sequence of cars moving with different velocities, which prevents the formation of a wide-range ordered flow pattern, reducing the total flow in the system.

  1. Phase diagram of 4D field theories with chiral anomaly from holography

    Energy Technology Data Exchange (ETDEWEB)

    Ammon, Martin; Leiber, Julian; Macedo, Rodrigo P. [Theoretisch-Physikalisches Institut, Friedrich-Schiller University of Jena,Max-Wien-Platz 1, 07743 Jena (Germany)


    Within gauge/gravity duality, we study the class of four dimensional CFTs with chiral anomaly described by Einstein-Maxwell-Chern-Simons theory in five dimensions. In particular we determine the phase diagram at finite temperature, chemical potential and magnetic field. At high temperatures the solution is given by an electrically and magnetically charged AdS Reissner-Nordstroem black brane. For sufficiently large Chern-Simons coupling and at sufficiently low temperatures and small magnetic fields, we find a new phase with helical order, breaking translational invariance spontaneously. For the Chern-Simons couplings studied, the phase transition is second order with mean field exponents. Since the entropy density vanishes in the limit of zero temperature we are confident that this is the true ground state which is the holographic version of a chiral magnetic spiral.

  2. Optical measurements of the phase diagram of Langmuir monolayers of fatty acid-alcohol mixtures (United States)

    Fischer, Birgit; Teer, Ellis; Knobler, Charles M.


    The surface pressure-temperature diagram of Langmuir monolayers of mixtures of heneicosanoic acid with heneicosanol has been determined from 10 °C to 40 °C by direct observation with Brewster angle microscopy. The measurements focused on the way in which the boundary between the L'2 and L2 phases change with composition. As previously observed by Shih et al. [J. Chem. Phys. 101, 9132 (1994)], it moves to lower pressure and higher temperature with increasing concentration of alcohol. We have discovered that the boundary between the Ov and L2 phases, which had not been studied before, moves in the opposite direction and that the L'2 and Ov phase regions merge, an unanticipated result.

  3. A statistical method for evaluation of the experimental phase equilibrium data of simple clathrate hydrates

    DEFF Research Database (Denmark)

    Eslamimanesh, Ali; Gharagheizi, Farhad; Mohammadi, Amir H.


    We, herein, present a statistical method for diagnostics of the outliers in phase equilibrium data (dissociation data) of simple clathrate hydrates. The applied algorithm is performed on the basis of the Leverage mathematical approach, in which the statistical Hat matrix, Williams Plot, and the r......We, herein, present a statistical method for diagnostics of the outliers in phase equilibrium data (dissociation data) of simple clathrate hydrates. The applied algorithm is performed on the basis of the Leverage mathematical approach, in which the statistical Hat matrix, Williams Plot......, and the residuals of a selected correlation results lead to define the probable outliers. This method not only contributes to outliers diagnostics but also identifies the range of applicability of the applied model and quality of the existing experimental data. The available correlation in the literature...... in exponential form is used to represent/predict the hydrate dissociation pressures for three-phase equilibrium conditions (liquid water/ice–vapor-hydrate). The investigated hydrate formers are methane, ethane, propane, carbon dioxide, nitrogen, and hydrogen sulfide. It is interpreted from the obtained results...

  4. Global phase diagram and quantum spin liquids in a spin-1/2 triangular antiferromagnet (United States)

    Gong, Shou-Shu; Zhu, W.; Zhu, J.-X.; Sheng, D. N.; Yang, Kun


    We study the spin-1 /2 Heisenberg model on the triangular lattice with the nearest-neighbor J1>0 , the next-nearest-neighobr J2>0 Heisenberg interactions, and the additional scalar chiral interaction Jχ(S⃗i×S⃗j) .S⃗k for the three spins in all the triangles using large-scale density matrix renormalization group calculation on cylinder geometry. With increasing J2 (J2/J1≤0.3 ) and Jχ (Jχ/J1≤1.0 ) interactions, we establish a quantum phase diagram with the magnetically ordered 120∘, stripe, and noncoplanar tetrahedral phase. In between these magnetic order phases, we find a chiral spin liquid (CSL) phase, which is identified as a ν =1 /2 bosonic fractional quantum Hall state with possible spontaneous rotational symmetry breaking. By switching on the chiral interaction, we find that the previously identified spin liquid in the J1-J2 triangular model (0.08 ≲J2/J1≲0.15 ) shows a phase transition to the CSL phase at very small Jχ. We also compute the spin triplet gap in both spin liquid phases, and our finite-size results suggest a large gap in the odd topological sector but a small or vanishing gap in the even sector. We discuss the implications of our results on the nature of the spin liquid phases.

  5. Construction of a DOPC/PSM/cholesterol phase diagram based on the fluorescence properties of trans-parinaric acid. (United States)

    Nyholm, Thomas K M; Lindroos, Daniel; Westerlund, Bodil; Slotte, J Peter


    Cell membranes have a nonhomogenous lateral organization. Most information about such nonhomogenous mixing has been obtained from model membrane studies where defined lipid mixtures have been characterized. Various experimental approaches have been used to determine binary and ternary phase diagrams for systems under equilibrium conditions. Such phase diagrams are the most useful tools for understanding the lateral organization in cellular membranes. Here we have used the fluorescence properties of trans-parinaric acid (tPA) for phase diagram determination. The fluorescence intensity, anisotropy, and fluorescence lifetimes of tPA were measured in bilayers composed of one to three lipid components. All of these parameters could be used to determine the presence of liquid-ordered and gel phases in the samples. However, the clearest information about the phase state of the lipid bilayers was obtained from the fluorescence lifetimes of tPA. This is due to the fact that an intermediate-length lifetime was found in samples that contain a liquid-ordered phase and a long lifetime was found in samples that contained a gel phase, whereas tPA in the liquid-disordered phase has a markedly shorter fluorescence lifetime. On the basis of the measured fluorescence parameters, a phase diagram for the 1,2-dioleoyl-sn-glycero-3-phosphocholine/N-palmitoyl sphingomyelin/cholesterol system at 23 °C was prepared with a 5 mol % resolution. We conclude that tPA is a good fluorophore for probing the phase behavior of complex lipid mixtures, especially because multilamellar vesicles can be used. The determined phase diagram shows a clear resemblance to the microscopically determined phase diagram for the same system. However, there are also significant differences that likely are due to tPA's sensitivity to the presence of submicroscopic liquid-ordered and gel phase domains. © 2011 American Chemical Society

  6. Mixtures of cationic lipid O-ethylphosphatidylcholine with membrane lipids and DNA: phase diagrams. (United States)

    Koynova, Rumiana; MacDonald, Robert C


    Ethylphosphatidylcholines are positively charged membrane lipid derivatives, which effectively transfect DNA into cells and are metabolized by the cells. For this reason, they are promising nonviral transfection agents. With the aim of revealing the kinds of lipid phases that may arise when lipoplexes interact with cellular lipids during DNA transfection, temperature-composition phase diagrams of mixtures of the O-ethyldipalmitoylphosphatidylcholine with representatives of the major lipid classes (phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, cholesterol) were constructed. Phase boundaries were determined using differential scanning calorimetry and synchrotron x-ray diffraction. The effects of ionic strength and of DNA presence were examined. A large variety of polymorphic and mesomorphic structures were observed. Surprisingly, marked enhancement of the affinity for nonlamellar phases was observed in mixtures with phosphatidylethanolamine and cholesterol as well as with phosphatidylglycerol (previously reported). Because of the potential relevance to transfection, it is noteworthy that such phases form at close to physiological conditions, and in the presence of DNA. All four mixtures exhibit a tendency to molecular clustering in the gel phase, presumably due to the specific interdigitated molecular arrangement of the O-ethyldipalmitoylphosphatidylcholine gel bilayers. It is evident that a remarkably broad array of lipid phases could arise in transfected cells and that these could have significant effects on transfection efficiency. The data may be particularly useful for selecting possible "helper" lipids in the lipoplex formulations, and in searches for correlations between lipoplex structure and transfection activity.

  7. High Pressure-Temperature Phase Diagram of 1,1-diamino-2,2-dinitroethylene (United States)

    Bishop, Matthew; Chellappa, Raja; Liu, Zhenxian; Preston, Daniel; Sandstrom, Mary; Dattelbaum, Dana; Vohra, Yogesh; Velisavljevic, Nenad


    1,1-diamino-2,2-dinitroethelyne (FOX-7) is a less sensitive energetic material with performance comparable to commonly used secondary explosives such as RDX and HMX. At ambient pressure, FOX-7 exhibits complex polymorphism with at least three structurally distinct phases (α, β, and γ) . In this study, we have investigated the high P-T stability of FOX-7 polymorphs using synchrotron mid-infrared (MIR) spectroscopy. At ambient pressure, our MIR spectra confirmed the known α --> β (110 °C) and β --> γ (160 °C) phase transitions; as well as, indicated an additional phase transition, γ --> δ (210°C), with the δ phase being stable up to 250 °C prior to melt/decomposition. In situ MIR spectra obtained during isobaric heating at 0.9 GPa revealed that the α --> β transition occurs at 180 °C, while β --> β + δ phase transition shifted to 300 °C with suppression of γ phase. Decomposition was observed above 325 °C. Based on multiple high P-T measurements, we have established the first high P-T phase diagram of FOX-7. This work was, in part, supported by the US DOE under contract No. DE-AC52-06NA25396 and Science Campaign 2 Program. MB acknowledges additional support from the NSF BD program. Use of NSLS (DE-AC02-98CH10886) beamline U2A (COMPRES, No.EAR01-35554, CDAC).

  8. Novel phase diagram behavior and materials design in heterostructural semiconductor alloys. (United States)

    Holder, Aaron M; Siol, Sebastian; Ndione, Paul F; Peng, Haowei; Deml, Ann M; Matthews, Bethany E; Schelhas, Laura T; Toney, Michael F; Gordon, Roy G; Tumas, William; Perkins, John D; Ginley, David S; Gorman, Brian P; Tate, Janet; Zakutayev, Andriy; Lany, Stephan


    Structure and composition control the behavior of materials. Isostructural alloying is historically an extremely successful approach for tuning materials properties, but it is often limited by binodal and spinodal decomposition, which correspond to the thermodynamic solubility limit and the stability against composition fluctuations, respectively. We show that heterostructural alloys can exhibit a markedly increased range of metastable alloy compositions between the binodal and spinodal lines, thereby opening up a vast phase space for novel homogeneous single-phase alloys. We distinguish two types of heterostructural alloys, that is, those between commensurate and incommensurate phases. Because of the structural transition around the critical composition, the properties change in a highly nonlinear or even discontinuous fashion, providing a mechanism for materials design that does not exist in conventional isostructural alloys. The novel phase diagram behavior follows from standard alloy models using mixing enthalpies from first-principles calculations. Thin-film deposition demonstrates the viability of the synthesis of these metastable single-phase domains and validates the computationally predicted phase separation mechanism above the upper temperature bound of the nonequilibrium single-phase region.

  9. Spectroscopic investigation of cement hydrate phases and their chloride binding properties (United States)

    Yu, Ping

    This thesis investigates the chloride binding properties of the hydrate phases present in Portland cement paste and the relationships between chloride binding capacity and the structure of these phases, using primarily NMR spectroscopy, infrared spectroscopy, XRD, thermal analysis, and chemical analysis. It provides important basic data and new insights into the effects of the structure of the individual hydrate phases on their chloride binding properties, and the atomic level structural states and dynamic behavior of the bound chloride in the cement hydrate crystals and at the solid/solution interface. The chloride binding capacity depends on the structure and surface properties of the individual hydrates. Portlandite and AFm surfaces have high affinity for chloride due to their positive zeta-potentials. For C-S-H samples, the chloride binding capacity increases with increasing C/S ratio due to increased numbers of surface Ca-OH sites and decreased polymerization of silicate chains. Aluminum substitution in C-S-H is unfavorable for chloride binding due to reduced layer charge and increased chain polymerization. For all hydrate phases the mechanism of chloride binding is not simply electrostatic attraction. Formation of metal-chloride clusters in the solution and sorption in the Stem layer may contribute substantially. The bound chlorides near the cement hydrate surfaces are in water solvated environments similar to those in the bulk solution and are in rapid exchange (>2kHz) with free chloride in the bulk solution. The chloride concentration near the surfaces is much higher than in the equilibrium bulk solution, and the reorientational frequency of the water molecules solvating the bound chloride is slower than those in the bulk solution. Chloride has a well-defined structural site in Friedel's salt. In solid solutions between Friedel's salt and hydroxyl-AFm, chloride occurs predominantly in Cl-rich domains except at high OH-contents.

  10. Morphological phase diagrams of C60 and C70 films on graphite (United States)

    Sato, Kazuma; Tanaka, Tomoyasu; Akaike, Kouki; Kanai, Kaname


    The morphologies of C60 and C70 fullerene films vacuum-deposited onto graphite at various deposition rates and grown at several temperatures were investigated using atomic force microscopy. These fullerene films on graphite are model systems of physisorption of organic molecules that likely exhibit little chemical interaction with the graphite's surface. The morphologies of C60 and C70 films grown on graphite can be understood well from growth models previously reported. Comparison of the morphological phase diagrams obtained for C60 and C70 indicate that the diffusion properties of the adsorbed molecule are key in determining the morphology of the obtained film. The low diffusion rate of C70 resulted in various film morphologies for all deposition conditions tested. Also, the obtained phase diagrams can be understood by the results of fractal dimension analysis on the C60 and C70 islands. The fundamental understanding of film growth obtained using these ideal physisorption systems will aid in understanding film growth by other molecular adsorption systems.

  11. Phase Diagram and Breathing Dynamics of Red Blood Cell Motion in Shear Flow (United States)

    Bagchi, Prosenjit; Yazdani, Alireza


    We present phase diagrams of red blood cell dynamics in shear flow using three-dimensional numerical simulations. By considering a wide range of shear rate and interior-to-exterior fluid viscosity ratio, it is shown that the cell dynamics is often more complex than the well-known tank-treading, tumbling and swinging motion, and is characterized by an extreme variation of the cell shape. We identify such complex shape dynamics as `breathing' dynamics. During the breathing motion, the cell either completely aligns with the flow direction and the membrane folds inward forming two cusps, or, it undergoes large swinging motion while deep, crater-like dimples periodically emerge and disappear. At lower bending rigidity, the breathing motion occurs over a wider range of shear rates, and is often characterized by the emergence of a quad-concave shape. The effect of the breathing dynamics on the tank-treading-to-tumbling transition is illustrated by detailed phase diagrams which appear to be more complex and richer than those of vesicles. In a remarkable departure from classical theory of nondeformable cells, we find that there exists a critical viscosity ratio below which the transition is dependent on shear rate only. Supported by NSF.

  12. Phase diagrams and switching of voltage and magnetic field in dilute magnetic semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Escobedo, R. [Departamento de Matematica Aplicada y Ciencias de la Computacion, Universidad de Cantabria, 39005 Santander (Spain); Carretero, M.; Bonilla, L.L. [G. Millan Institute, Fluid Dynamics, Nanoscience and Industrial Maths., Universidad Carlos III de Madrid, 28911 Leganes (Spain); Unidad Asociada al Instituto de Ciencia de Materiales, CSIC, 28049 Cantoblanco, Madrid (Spain); Platero, G. [Instituto de Ciencia de Materiales, CSIC, 28049 Cantoblanco, Madrid (Spain)


    The response of an n-doped dc voltage biased II-VI multi-quantum well dilute magnetic semiconductor nanostructure having its first well doped with magnetic (Mn) impurities is analyzed by sweeping wide ranges of both the voltage and the Zeeman level splitting induced by an external magnetic field. The level splitting versus voltage phase diagram shows regions of stable self-sustained current oscillations immersed in a region of stable stationary states. Transitions between stationary states and self-sustained current oscillations are systematically analyzed by both voltage and level splitting abrupt switching. Sudden voltage or/and magnetic field changes may switch on current oscillations from an initial stationary state, and reciprocally, current oscillations may disappear after sudden changes of voltage or/and magnetic field changes into the stable stationary states region. The results show how to design such a device to operate as a spin injector and a spin oscillator by tuning the Zeeman splitting (through the applied external magnetic field), the applied voltage and the sample configuration parameters (doping density, barrier and well widths, etc.) to select the desired stationary or oscillatory behavior. Phase diagram of Zeeman level splitting {delta} vs. dimensionless applied voltage {phi} for N = 10 QWs. White region: stable stationary states; black: stable self-sustained current oscillations. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. New Wang-Landau approach to obtain phase diagrams for multicomponent alloys (United States)

    Takeuchi, Kazuhito; Tanaka, Ryohei; Yuge, Koretaka


    We develop an approach to apply the Wang-Landau algorithm to multicomponent alloys in a semi-grand-canonical ensemble. Although the Wang-Landau algorithm has great advantages over conventional sampling methods, there are few applications to alloys. This is because calculating compositions in a semi-grand-canonical ensemble via the Wang-Landau algorithm requires a multidimensional density of states in terms of total energy and compositions, and constructing it is difficult from the viewpoints of both implementation and computational cost. In this study, we develop a simple approach to calculate the alloy phase diagram based on the Wang-Landau algorithm, and show that a number of one-dimensional densities of states could lead to compositions in a semi-grand-canonical ensemble as a multidimensional density of states could. Finally, we apply the present method to Cu-Au and Pd-Rh alloys and confirm that the present method successfully describes the phase diagram with high efficiency, validity, and accuracy.

  14. Finite-connectivity spin-glass phase diagrams and low-density parity check codes. (United States)

    Migliorini, Gabriele; Saad, David


    We obtain phase diagrams of regular and irregular finite-connectivity spin glasses. Contact is first established between properties of the phase diagram and the performance of low-density parity check (LDPC) codes within the replica symmetric (RS) ansatz. We then study the location of the dynamical and critical transition points of these systems within the one step replica symmetry breaking theory (RSB), extending similar calculations that have been performed in the past for the Bethe spin-glass problem. We observe that the location of the dynamical transition line does change within the RSB theory, in comparison with the results obtained in the RS case. For LDPC decoding of messages transmitted over the binary erasure channel we find, at zero temperature and rate , an RS critical transition point at while the critical RSB transition point is located at , to be compared with the corresponding Shannon bound . For the binary symmetric channel we show that the low temperature reentrant behavior of the dynamical transition line, observed within the RS ansatz, changes its location when the RSB ansatz is employed; the dynamical transition point occurs at higher values of the channel noise. Possible practical implications to improve the performance of the state-of-the-art error correcting codes are discussed.

  15. Superior thermoelectric response in the 3R phases of hydrated NaxRhO2

    KAUST Repository

    Saeed, Y.


    Density functional theory is used to investigate the thermoelectric properties of the 3R phases of NaxRhO2 for different Na vacancy configurations and concentrations. As compared to the analogous 2H phases, the modified stacking of the atomic layers in the 3R phases reduces the interlayer coupling. As a consequence, the 3R phases are found to be superior in the technologically relevant temperature range. The Rh d3z2-r2 orbitals still govern the valence band maxima and therefore determine the transport properties. A high figure of merit of 0.35 is achieved in hydrated Na0.83RhO2 at 580 K by water intercalation, which is 34% higher than in the non-hydrated phase.

  16. Phase diagram of dense two-color QCD within lattice simulations

    Directory of Open Access Journals (Sweden)

    Braguta V.V.


    Full Text Available We present the results of a low-temperature scan of the phase diagram of dense two-color QCD with Nf = 2 quarks. The study is conducted using lattice simulation with rooted staggered quarks. At small chemical potential we observe the hadronic phase, where the theory is in a confining state, chiral symmetry is broken, the baryon density is zero and there is no diquark condensate. At the critical point μ = mπ/2 we observe the expected second order transition to Bose-Einstein condensation of scalar diquarks. In this phase the system is still in confinement in conjunction with nonzero baryon density, but the chiral symmetry is restored in the chiral limit. We have also found that in the first two phases the system is well described by chiral perturbation theory. For larger values of the chemical potential the system turns into another phase, where the relevant degrees of freedom are fermions residing inside the Fermi sphere, and the diquark condensation takes place on the Fermi surface. In this phase the system is still in confinement, chiral symmetry is restored and the system is very similar to the quarkyonic state predicted by SU(Nc theory at large Nc.

  17. Study of the phase diagram of dense two-color QCD within lattice simulation

    CERN Document Server

    Braguta, V V; Kotov, A Yu; Molochkov, A V; Nikolaev, A A


    In this paper we carry out a low-temperature scan of the phase diagram of dense two-color QCD with $N_f=2$ quarks. The study is conducted using lattice simulation with rooted staggered quarks. At small chemical potential we observe the hadronic phase, where the theory is in a confining state, chiral symmetry is broken, the baryon density is zero and there is no diquark condensate. At the critical point $\\mu = m_{\\pi}/2$ we observe the expected second order transition to Bose-Einstein condensation of scalar diquarks. In this phase the system is still in confinement in conjunction with nonzero baryon density, but the chiral symmetry is restored in the chiral limit. We have also found that in the first two phases the system is well described by chiral perturbation theory. For larger values of the chemical potential the system turns into another phase, where the relevant degrees of freedom are fermions residing inside the Fermi sphere, and the diquark condensation takes place on the Fermi surface. In this phase t...

  18. Magnetic structures, phase diagram and spin waves of magneto-electric LiNiPO4

    DEFF Research Database (Denmark)

    Jensen, Thomas Bagger Stibius


    LiNiPO4 is a magneto-electric material, having co-existing antiferromagnetic and ferroelectric phases when suitable magnetic fields are applied at low temperatures. Such systems have received growing interest in recent years, but the nature of the magneticelectric couplings is yet to be fully...... understand. Hopefully, studying LiNiPO4 will shed further light on the subject, especially since the crystal structure of LiNiPO4 is rather simple compared to most relevant multiferroic materials. Although the study of the magnetic-electric couplings is of main interest to the many scientists guiding me...... through the last three years, it is not the primary subject of this thesis. The objective of the phD project has been to provide groundwork that may be beneficiary to future studies of LiNiPO4. More specifically, we have mapped out the magnetic HT phase diagram with magnetic fields below 14.7 T applied...

  19. Thermodynamic studies of mixtures for topical anesthesia: Lidocaine-salol binary phase diagram

    Energy Technology Data Exchange (ETDEWEB)

    Lazerges, Mathieu [Laboratoire de Chimie Physique (EA 4066), Faculte des Sciences Pharmaceutiques et Biologiques, Universite Paris Descartes, 4 Avenue de l' Observatoire, 75270 Paris Cedex 06 (France); Rietveld, Ivo B., E-mail: [Laboratoire de Chimie Physique (EA 4066), Faculte des Sciences Pharmaceutiques et Biologiques, Universite Paris Descartes, 4 Avenue de l' Observatoire, 75270 Paris Cedex 06 (France); Corvis, Yohann; Ceolin, Rene; Espeau, Philippe [Laboratoire de Chimie Physique (EA 4066), Faculte des Sciences Pharmaceutiques et Biologiques, Universite Paris Descartes, 4 Avenue de l' Observatoire, 75270 Paris Cedex 06 (France)


    The lidocaine-salol binary system has been investigated by differential scanning calorimetry, direct visual observations, and X-ray powder diffraction, resulting in a temperature-composition phase diagram with a eutectic equilibrium. The eutectic mixture, found at 0.423 {+-} 0.007 lidocaine mole-fraction, melts at 18.2 {+-} 0.5 {sup o}C with an enthalpy of 17.3 {+-} 0.5 kJ mol{sup -1}. This indicates that the liquid phase around the eutectic composition is stable at room temperature. Moreover, the undercooled liquid mixture does not easily crystallize. The present binary mixture exhibits eutectic behavior similar to the prilocaine-lidocaine mixture in the widely used EMLA topical anesthetic preparation.

  20. High-pressure high-temperature phase diagram of organic crystal paracetamol (United States)

    Smith, Spencer J.; Montgomery, Jeffrey M.; Vohra, Yogesh K.


    High-pressure high-temperature (HPHT) Raman spectroscopy studies have been performed on the organic crystal paracetamol in a diamond anvil cell utilizing boron-doped heating diamond anvil. Isobaric measurements were conducted at pressures up to 8.5 GPa and temperature up to 520 K in five different experiments. Solid state phase transitions from monoclinic Form I  →  orthorhombic Form II were observed at various pressures and temperatures as well as transitions from Form II  →  unknown Form IV. The melting temperature for paracetamol was observed to increase with increasing pressures to 8.5 GPa. This new data is combined with previous ambient temperature high-pressure Raman and x-ray diffraction data to create the first HPHT phase diagram of paracetamol.

  1. Automated Generation of Phase Diagrams for Binary Systems with Azeotropic Behavior

    DEFF Research Database (Denmark)

    Cismondi, Martin; Michelsen, Michael Locht; Zabaloy, Marcelo S.


    's azeotropic end points (AEPs). These can exist on vapor-liquid (VL) critical lines (CAEPs), on liquid-liquid-vapor (LLV) lines (HAEPs), and on pure-compound vapor pressure lines (PAEPs). Next, for the chosen binary system, we generate one or two azeotropic lines. Each of these lines has, as its starting point......, one of the previously identified AEPs. We calculate the azeotropic lines using a numerical continuation method that solves the nonlinear azeotropic system of equations under a range of conditions and efficiently tracks entire azeotropic curves. We have integrated our strategy for calculating...... azeotropic lines into a general algorithm for the single-run computation of binary global phase equilibrium diagrams (GPEDs). GPEDs are defined by pure-compound, critical, LLV, and azeotropic lines. We implemented this general algorithm in the computer program GPEC (Global Phase Equilibrium Calculations...

  2. Phase diagram of SU(2) with 2 flavors of dynamical adjoint quarks

    CERN Document Server

    Catterall, Simon; Sannino, Francesco; Schneible, Joe


    We report on numerical simulations of SU(2) lattice gauge theory with two flavors of light dynamical quarks in the adjoint of the gauge group. The dynamics of this theory is thought to be very different from QCD -- the theory exhibiting conformal or near conformal behavior in the infrared. We make a high resolution survey of the phase diagram of this model in the plane of the bare coupling and quark mass on lattices of size 8^3 \\times 16. Our simulations reveal a line of first order phase transitions extending from beta=0 to beta=beta_c \\sim 2.0. For beta > beta_c the line is no longer first order but continues as the locus of minimum meson mass. For beta > 2.0 we observe the critical pion and rho masses to be light, independent of bare coupling and approximately degenerate. We discuss possible interpretations of these observations and corresponding continuum limits.

  3. A non-classical phase diagram for virus-bacterial co-evolution mediated by CRISPR (United States)

    Han, Pu; Deem, Michael

    CRISPR is a newly discovered prokaryotic immune system. Bacteria and archaea with this system incorporate genetic material from invading viruses into their genomes, providing protection against future infection by similar viruses. Due to the cost of CRISPR, bacteria can lose the acquired immunity. We will show an intriguing phase diagram of the virus extinction probability, which when the rate of losing the acquired immunity is small, is more complex than that of the classic predator-prey model. As the CRISPR incorporates genetic material, viruses are under pressure to evolve to escape the recognition by CRISPR, and this co-evolution leads to a non-trivial phase structure that cannot be explained by the classical predator-prey model.

  4. Optimization of the thermodynamic properties and phase diagrams of P2O5-containing systems (United States)

    Hudon, Pierre; Jung, In-Ho


    P2O5 is an important oxide component in the late stage products of numerous igneous rocks such as granites and pegmatites. Typically, P2O5 combines with CaO and crystallizes in the form of apatite, while in volatile-free conditions, Ca-whitlockite is formed. In spite of their interest, the thermodynamic properties and phase diagrams of P2O5-containg systems are not well known yet. In the case of the pure P2O5 for example, no experimental thermodynamic data are available for the liquid and the O and O' solid phases. As a result, we re-evaluated all the thermodynamic and phase diagram data of the P2O5 unary system [1]. Optimization of the thermodynamic properties and phase diagrams of the binary P2O5 systems was then performed including the Li2O-, Na2O-, MgO-, CaO-, BaO-, MnO-, FeO-, Fe2O3-, ZnO-, Al2O3-, and SiO2-P2O5 [2] systems. All available thermodynamic and phase equilibrium data were simultaneously reproduced in order to obtain a set of model equations for the Gibbs energies of all phases as functions of temperature and composition. In particular, the Gibbs energy of the liquid solution was described using the Modified Quasichemical Model [3-5] implemented in the FactSage software [6]. Thermodynamic modeling of the Li2O-Na2O-K2O-MgO-CaO-FeO-Fe2O3-Al2O3-SiO2 system, which include many granite-forming minerals such as nepheline, leucite, pyroxene, melilite, feldspar and spinel is currently in progress. [1] Jung, I.-H., Hudon, P. (2012) Thermodynamic assessment of P2O5. J. Am. Ceram. Soc., 95 (11), 3665-3672. [2] Rahman, M., Hudon, P. and Jung, I.-H. (2013) A coupled experimental study and thermodynamic modeling of the SiO2-P2O5 system. Metall. Mater. Trans. B, 44 (4), 837-852. [3] Pelton, A.D. and Blander, M. (1984) Computer-assisted analysis of the thermodynamic properties and phase diagrams of slags. Proc. AIME Symp. Metall. Slags Fluxes, TMS-AIME, 281-294. [4] Pelton, A.D. and Blander, M. (1986) Thermodynamic analysis of ordered liquid solutions by a modified

  5. Experiments on a strongly correlated material: photoresponse, phase diagram and hydrogen doping of vanadium dioxide (United States)

    Kasirga, T. Serkan

    The metal-insulator transition (MIT) in vanadium dioxide (VO2) has attracted waves of attention after its rst observation by Morin in 1959. There are several reasons for the interest in this material. First, its metal-insulator transition is at an easily accessible temperature which allows investigators to study the eect of strong electronic correlations with little eort. Second reason is VO2 oers many applications, although most of them are mundane, a few may have signicant eects on dierent areas of technology. However, even after over half a century there is still a debate about the nature of the MIT and non of the applications proposed have been realized. The main culprit for this is the diculties in studying the bulk crystals of VO 2. In bulk crystals, defects in the crystal, impurities and domain structure causes irreproducible results. This combined with the theoretical challenges made studying VO2 and realization of applications impractical. However, recent discovery of the growth technique for growing the nano-scale crystals, revitalized the interest in VO2. In this dissertation I present the experimental studies that we performed on VO2. I discussed the ndings from three major studies we performed; photoresponse, finding the strain-temperature phase diagram and hydrogen doping of VO2. We used scanning photocurrent microscopy technique to reveal the light-matter interaction in VO2. Suspended nanobeam devices are used in the experiments and results revealed that photoresponse of VO2 is dominated by the thermal eects and there is no photovoltaic contribution. Results are published in Nature Nanotechnology in 2012 . In the second study, we determined the strain-temperature phase stability diagram of VO2. This is the first ever determination of the phase diagram of a solid state phase transition. Also our studies revealed that the triple point coincides with the critical point, which has important implications for both theoretical studies of the MIT in VO 2 and

  6. Communication: Protein dynamical transition vs. liquid-liquid phase transition in protein hydration water (United States)

    Schirò, Giorgio; Fomina, Margarita; Cupane, Antonio


    In this work, we compare experimental data on myoglobin hydrated powders from elastic neutron scattering, broadband dielectric spectroscopy, and differential scanning calorimetry. Our aim is to obtain new insights on the connection between the protein dynamical transition, a fundamental phenomenon observed in proteins whose physical origin is highly debated, and the liquid-liquid phase transition (LLPT) possibly occurring in protein hydration water and related to the existence of a low temperature critical point in supercooled water. Our results provide a consistent thermodynamic/dynamic description which gives experimental support to the LLPT hypothesis and further reveals how fundamental properties of water and proteins are tightly related.

  7. Finite size and Coulomb corrections: from nuclei to nuclear liquid vapor phase diagram

    Energy Technology Data Exchange (ETDEWEB)

    Moretto, L.G.; Elliott, J.B.; Phair, L. [Lawrence Berkeley National Laboratory, Nuclear Science Division (United States)


    In this paper we consider the problem of obtaining the infinite symmetric uncharged nuclear matter phase diagram from a thermal nuclear reaction. In the first part we shall consider the Coulomb interaction which, because of its long range makes the definition of phases problematic. This Coulomb effect seems truly devastating since it does not allow one to define nuclear phase transitions much above A {approx} 30. However there may be a solution to this difficulty. If we consider the emission of particles with a sizable charge, we notice that a large Coulomb barrier Bc is present. For T << Bc these channels may be considered effectively closed. Consequently the unbound channels may not play a role on a suitably short time scale. Then a phase transition may still be definable in an approximate way. In the second part of the article we shall deal with the finite size problem by means of a new method, the complement method, which shall permit a straightforward extrapolation to the infinite system. The complement approach consists of evaluating the change in free energy occurring when a particle or cluster is moved from one (finite) phase to another. In the case of a liquid drop in equilibrium with its vapor, this is done by extracting a vapor particle of any given size from the drop and evaluating the energy and entropy changes associated with both the vapor particle and the residual liquid drop (complement)

  8. Phase diagram and neutron spin resonance of superconducting NaFe1 -xCuxAs (United States)

    Tan, Guotai; Song, Yu; Zhang, Rui; Lin, Lifang; Xu, Zhuang; Tian, Long; Chi, Songxue; Graves-Brook, M. K.; Li, Shiliang; Dai, Pengcheng


    We use transport and neutron scattering to study the electronic phase diagram and spin excitations of NaFe1 -xCuxAs single crystals. Similar to Co- and Ni-doped NaFeAs, a bulk superconducting phase appears near x ≈2 % with the suppression of stripe-type magnetic order in NaFeAs. Upon further increasing Cu concentration the system becomes insulating, culminating in an antiferromagnetically ordered insulating phase near x ≈50 % . Using transport measurements, we demonstrate that the resistivity in NaFe1 -xCuxAs exhibits non-Fermi-liquid behavior near x ≈1.8 % . Our inelastic neutron scattering experiments reveal a single neutron spin resonance mode exhibiting weak dispersion along c axis in NaFe0.98Cu0.02As . The resonance is high in energy relative to the superconducting transition temperature Tc but weak in intensity, likely resulting from impurity effects. These results are similar to other iron pnictides superconductors despite that the superconducting phase in NaFe1 -xCuxAs is continuously connected to an antiferromagnetically ordered insulating phase near x ≈50 % with significant electronic correlations. Therefore, electron correlations is an important ingredient of superconductivity in NaFe1 -xCuxAs and other iron pnictides.

  9. Phase diagram of germanium telluride encapsulated in carbon nanotubes from first-principles searches (United States)

    Wynn, Jamie M.; Medeiros, Paulo V. C.; Vasylenko, Andrij; Sloan, Jeremy; Quigley, David; Morris, Andrew J.


    Germanium telluride has attracted great research interest, primarily because of its phase-change properties. We have developed a general scheme, based on the ab initio random structure searching (AIRSS) method, for predicting the structures of encapsulated nanowires, and using this we predict a number of thermodynamically stable structures of GeTe nanowires encapsulated inside carbon nanotubes of radii under 9 Å . We construct the phase diagram of encapsulated GeTe, which provides quantitative predictions about the energetic favorability of different filling structures as a function of the nanotube radius, such as the formation of a quasi-one-dimensional rock-salt-like phase inside nanotubes of radii between 5.4 and 7.9 Å . Simulated TEM images of our structures show excellent agreement between our results and experimental TEM imagery. We show that, for some nanotubes, the nanowires undergo temperature-induced phase transitions from one crystalline structure to another due to vibrational contributions to the free energy, which is a first step toward nano-phase-change memory devices.

  10. Calcium silicate hydrates: Solid and liquid phase composition

    Energy Technology Data Exchange (ETDEWEB)

    Lothenbach, Barbara, E-mail: [Laboratory Concrete & Construction Chemistry, Empa (Switzerland); Nonat, André [ICB, UMR CNRS 6303 CNRS-Université de Bourgogne, Faculté des Sciences et Techniques, BP47870, 21078 Dijon Cedex (France)


    This paper presents a review on the relationship between the composition, the structure and the solution in which calcium silicate hydrate (C–S–H) is equilibrated. The silica chain length in C–S–H increases with the silicon concentration and the calcium content in the interlayer space with the calcium concentrations. Sodium and potassium are taken up in the interlayer space, preferentially at low calcium concentrations and thus by low Ca/Si C–S–H. Aluminium uptake in C–S–H increases strongly at higher aluminium concentrations in the solution. At low Ca/Si, aluminium substitutes silica in the bridging position, at Ca/Si > 1 aluminium is bound in TAH. Recently developed thermodynamic models are closely related to the structure of C–S–H and tobermorite, and able to model not only the solubility and the chemical composition of the C–S–H, but also to predict the mean silica chain length and the uptake of aluminium.

  11. Summation of all petal-shaped diagrams in O(N) model near the phase transition temperature

    CERN Document Server

    Bordag, M


    The temperature phase transition in the theory of the N-component scalar field is studied. The weak phase transition of the first order is obtained in the approximation of summation of all petal-shaped diagrams. By the N -> infinity it becomes the phase transition of the second order. The comparison with other approaches is carried out. The necessary data on the Legendre transformation of the second order and Schwinger-Dyson equations are presented. The gap equations are solved in the approximation of summation of all petal-shaped diagrams for the arbitrary N

  12. Correlation between viscous-flow activation energy and phase diagram in four systems of Cu-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ning Shuang [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Bian Xiufang, E-mail: [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Ren Zhenfeng [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China)


    Activation energy is obtained from temperature dependence of viscosities by means of a fitting to the Arrhenius equation for liquid alloys of Cu-Sb, Cu-Te, Cu-Sn and Cu-Ag systems. We found that the changing trend of activation energy curves with concentration is similar to that of liquidus in the phase diagrams. Moreover, a maximum value of activation energy is in the composition range of the intermetallic phases and a minimum value of activation energy is located at the eutectic point. The correlation between the activation energy and the phase diagrams has been further discussed.

  13. Feasibility of using phase change materials to control the heat of hydration in massive concrete structures. (United States)

    Choi, Won-Chang; Khil, Bae-Soo; Chae, Young-Seok; Liang, Qi-Bo; Yun, Hyun-Do


    This paper presents experimental results that can be applied to select a possible phase change material (PCM), such as a latent heat material (LHM), to control the hydration heat in mass concrete structures. Five experimental tests (microconduction, simplified adiabatic temperature rise, heat, and compressive strength tests) were conducted to select the most desirable LHM out of seven types of inorganic PCM used in cement mortar and to determine the most suitable mix design. The results of these experimental tests were used to assess the feasibility of using PCM to reduce hydration heat in mass concrete that was examined. The experimental results show that cement mortar containing barium- [Ba(OH)2 · 8H2O] based PCM has the lowest amount of total hydration heat of the cement pastes. The barium-based PCM provides good latent heat properties that help to prevent volume change and microcracks caused by thermal stress in mass concrete.

  14. Sorption Mechanisms of Eu(3+) on CSH Phases of Hydrated Cements. (United States)

    Pointeau, Ingmar; Piriou, Bernard; Fedoroff, Michel; Barthes, Marie-Genevieve; Marmier, Nicolas; Fromage, Francine


    The sorption mechanisms of Eu(3+) on calcium silicate hydrate (CSH) phases of hydrated cement were investigated as a tool for the prediction of the behavior of trivalent radionuclides with aged/degraded cements in radioactive waste repositories. Four techniques were used: site-selective and time-resolved luminescence spectroscopy, XPS, high-resolution SEM coupled with EDX, and XRD. Results showed that europium is not precipitated in the solution despite its low solubility limit. It is strongly retained on CSH, resulting in a more than 99.8% sorption rate. Two main sorption sites were characterized by luminescence spectroscopy. One site, with a long lifetime, can be interpreted as Eu included in the framework of CSH. Another one, with a shorter lifetime, can be interpreted as a site with a hydrated environment that is high but is less than that of europium hydroxide. It corresponds to superficial complexation or precipitation. Copyright 2001 Academic Press.

  15. Fluid balance and hydration assessment during the weight-stable preparation phase in elite youth boxers. (United States)

    Zubac, Damir; Antelj, Tomislav; Olujic, Dragana; Ivancev, Vladimir; Morrison, Shawnda A


    This study investigated (i) the prevalence of hypohydration and (ii) association between urinary indices of hydration status and confounding factors (e.g., urine protein content, water intake) in elite youth boxers during their weight-stable phase before competition. Sixteen national champion boxers (all male, 17 ± 1 y) were measured on 3 occasions (baseline, day 3, day 10), 30-day prior to competition. Body mass, total body water, urine specific gravity (USG), osmolality (UOSM) and total protein content (TPC) were evaluated to determine hydration status and fluid balance. Overall macronutrient and water intake were assessed using dietary records. Both UOSM and USG increased from day 3 to day 10 by 16% and 0.4% (P hydration status in competition exhibit large variability, even during weight-stable periods.

  16. Feasibility of Using Phase Change Materials to Control the Heat of Hydration in Massive Concrete Structures

    Directory of Open Access Journals (Sweden)

    Won-Chang Choi


    Full Text Available This paper presents experimental results that can be applied to select a possible phase change material (PCM, such as a latent heat material (LHM, to control the hydration heat in mass concrete structures. Five experimental tests (microconduction, simplified adiabatic temperature rise, heat, and compressive strength tests were conducted to select the most desirable LHM out of seven types of inorganic PCM used in cement mortar and to determine the most suitable mix design. The results of these experimental tests were used to assess the feasibility of using PCM to reduce hydration heat in mass concrete that was examined. The experimental results show that cement mortar containing barium- [Ba(OH2·8H2O] based PCM has the lowest amount of total hydration heat of the cement pastes. The barium-based PCM provides good latent heat properties that help to prevent volume change and microcracks caused by thermal stress in mass concrete.

  17. The phase diagram and the magnetic structure of nuclear spins in elemental copper below 60 nK

    DEFF Research Database (Denmark)

    Siemensmeyer, K.; Steiner, M.; Weinfurther, H.


    The phase diagram for nuclear magnetic order is elemental copper and the corresponding ordering vectors were investigated by neutron diffraction at nanokelvin temperatures. The intermediate phase is characterized by an ordering vector (O 2/3 2/3). This is the first time that this type of order...

  18. Ecological and climatic consequences of phase instability of gas hydrates on the ocean bed (United States)

    Balanyuk, I.; Dmitrievsky, A.; Akivis, T.; Chaikina, O.


    energy and gas that leads to explosion. Methane is the main natural source for power engineering specialists. It is transported by pipelines, and gas hydrate is dangerous in this case too. It can block the gas pipeline system forming the so-called "trombus" of "thermal ice". After that the pipes have to be opened. The mess of this strange ice discovered melts immediately releasing methane and water vapor. The trombus formation can be prevented by the temperature increase or the pressure decrease. Both methods are very uncomfortable under the conditions the pipelines work. The better method is thorough drying up of the gas because gas hydrate obviously cannot be formed without water. Gas hydrates attract attention not only as a fuel and chemical stuff but in relation to a serious anxiety of strong ecological and climatic problems that can occur as a result of methane release to the atmosphere due to both gas hydrate deposits development and minor changes in thermodynamic conditions in the vicinity of a threshold of gas hydrate phase stability. One of the most probable causes is the global warming of the Earth due to the hothouse effect because the specific absorption of the Earth heat radiation by methane (radiation effectivity) is 21 times higher than its absorption by carbonic gas. Analysis of the air trapped by polar ice show that contemporary increase of methane concentration in the atmosphere is unexampled for the last 160 thousands of years. The sources of this increase are not clear. Observer and latent methane bursts during natural gas hydrates decomposition can be considered as a probable source. Amount of methane hided in natural gas hydrates is 3000 times higher its amount in the atmosphere. Release of this hothouse potential would have terrible consequences for the humanity. The warming can cause further gas hydrates decomposition and released methane will cause the following warming. Thus, self-accelerating process can start. The most vulnerable for the

  19. Study of agglomeration of ice particles and of trichlorofluoromethane hydrate particles suspended in a hydrocarbon phase

    Energy Technology Data Exchange (ETDEWEB)

    Colombel, E.; Palermo, T.; Barre, L.; Gateau, P. [Inst. Francais du Petrole, Rueil Malmaison (France). Dept. of Applied Chemistry and Physico-Chemistry; Gruy, F. [Ecole Nationale Superieure des Mines, Saint Etienne (France)


    Gas hydrates may lead to pipeline blockage during oil production in offshore conditions. A study was conducted to better understand the agglomeration mechanism of gas hydrate particles in water in oil emulsions. The model system chosen to study this mechanism was ice or trichlorofluoromethane (CCl{sub 3}F) hydrate particles dispersed in xylene with asphaltenes as surfactants. The system illustrated what occurs in pipelines as produced water with oil is dispersed by surfactants that are naturally present in the oil phase. Freon was selected because it models methane behaviour very well. Both methane and freon are soluble in oil and insoluble in water. CCl{sub 3}F hydrates are stable under atmospheric pressure. As such, different techniques can be applied without being limited by high pressure conditions. The agglomeration mechanism in these particles can be modelled and compared with ice crystals. This study focused on the kinetics of agglomeration formation and mechanisms of hydrate and ice particle agglomeration in a hydrocarbon phase. Two characterization techniques were implemented in this study, notably nuclear magnetic resonance (NMR) relaxometry and rheology. The different relaxation rate for solids or liquids was used to monitor in situ the ratio between the solid and total hydrogen or fluorine as a function of time with controlled shearing conditions. NMR provided information on the formation kinetics and the conversion rate of water in ice crystals. The rest of the study focused on the formation of Freon hydrate crystals. The study confirmed that the physico-chemistry of the water/oil interface has an important role in agglomeration. 9 refs., 5 tabs., 18 figs.

  20. Dynamical phase diagram of quantum spin chains with long-range interactions (United States)

    Halimeh, Jad C.; Zauner-Stauber, Valentin


    Using an infinite matrix product state (iMPS) technique based on the time-dependent variational principle (TDVP), we study two major types of dynamical phase transitions (DPT) in the one-dimensional transverse-field Ising model (TFIM) with long-range power-law (∝1 /rα with r interspin distance) interactions out of equilibrium in the thermodynamic limit—DPT-I: based on an order parameter in a (quasi-)steady state, and DPT-II: based on nonanalyticities (cusps) in the Loschmidt-echo return rate. We construct the corresponding rich dynamical phase diagram, while considering different quench initial conditions. We find a nontrivial connection between both types of DPT based on their critical lines. Moreover, and very interestingly, we detect a new DPT-II dynamical phase in a certain range of interaction exponent α , characterized by what we call anomalous cusps that are distinct from the regular cusps usually associated with DPT-II. Our results provide the characterization of experimentally accessible signatures of the dynamical phases studied in this work.

  1. Electronic phase diagram of LixCoO2 revisited with potentiostatically deintercalated single crystals (United States)

    Ou-Yang, T. Y.; Huang, F.-T.; Shu, G. J.; Lee, W. L.; Chu, M.-W.; Liu, H. L.; Chou, F. C.


    Electronic phase diagram of LixCoO2 has been reexamined using potentiostatically de-intercalated single-crystal samples. Stable phases of x˜0.87, 0.72, 0.53, 0.50, 0.43, and 0.33 were found and isolated for physical property studies. A-type and chain-type antiferromagnetic orderings have been suggested from magnetic susceptibility measurement results in x˜0.87 and 0.50 below approximately 10 and 200 K, respectively, similar to those found in NaxCoO2 system. There is no Li vacancy superlattice ordering observed at room temperature for the electronically stable phase Li0.72CoO2 as revealed by synchrotron x-ray Laue diffraction. The peculiar magnetic anomaly near ˜175 K as often found in powder samples of x˜0.46-0.78 cannot be isolated through this single-crystal potentiostatic method, which supports the previously proposed explanation to be a surface stabilized phase of significant thermal hysteresis and aging character.

  2. Monte Carlo modeling the phase diagram of magnets with the Dzyaloshinskii - Moriya interaction (United States)

    Belemuk, A. M.; Stishov, S. M.


    We use classical Monte Carlo calculations to model the high-pressure behavior of the phase transition in the helical magnets. We vary values of the exchange interaction constant J and the Dzyaloshinskii-Moriya interaction constant D, which is equivalent to changing spin-spin distances, as occurs in real systems under pressure. The system under study is self-similar at D / J = constant , and its properties are defined by the single variable J / T , where T is temperature. The existence of the first order phase transition critically depends on the ratio D / J . A variation of J strongly affects the phase transition temperature and width of the fluctuation region (the ;hump;) as follows from the system self-similarity. The high-pressure behavior of the spin system depends on the evolution of the interaction constants J and D on compression. Our calculations are relevant to the high pressure phase diagrams of helical magnets MnSi and Cu2OSeO3.

  3. Pseudo-ternary phase diagrams of lecithin-based microemulsions: influence of monoalkylphosphates. (United States)

    Trotta, M; Ugazio, E; Gasco, M R


    The formation of macroscopically homogeneous, stable, fluid, optically transparent, isotropic solutions (microemulsions) was delineated, at 25 degrees C, for systems containing water, soybean lecithin, sodium monoalkylphosphate (hexyl or ocytl), alcohol and isopropyl myristate. Six straight or branched alcohols (1-butanol, 2-butanol, isobutanol, 1-pentanol, 2-pentanol, 3-pentanol) were investigated as co-surfactants. A constant lecithin/alcohol mixing ratio was used, while the aqueous phase consisted of a solution of alkylphosphates at different concentrations. An increase of the microemulsion domain was seen by increasing the concentration of the alkylphosphate. With 0.2m hexylphosphate, as aqueous phase, the microemulsion domain consisted of a single, region, that, in the presence of butylic alcohols, spanded the greater portion of the phase diagram. In the presence of amyl alcohols the area of this region was much smaller. With 0.2 m octylphosphate the realm of existence of the microemulsions, except for 1-pentanol, consisted of two regions separated by a liquid-crystal region. With all the alcohols examined, the liquid-crystal phase solubilized a larger amount of oil in the presence of octylphosphate than in the presence of hexylphosphate. The stability ranges of microemulsions in systems containing soybean, lecithin, alcohol, water, and isopropyl myristate can be greatly increased by using a second hydrophobic amphiphile, such as hexylphosphate, to adjust the hydrophilic-lipophilic balance or the spontaneous peaking properties of lecithin-alcohol systems.

  4. Quantum phase diagram of the half filled Hubbard model with bond-charge interaction

    Energy Technology Data Exchange (ETDEWEB)

    Dobry, A.O., E-mail: [Facultad de Ciencias Exactas Ingenieria y Agrimensura, Universidad Nacional de Rosario and Instituto de Fisica Rosario, Bv. 27 de Febrero 210 bis, 2000 Rosario (Argentina); Aligia, A.A. [Centro Atomico Bariloche and Instituto Balseiro, Comision Nacional de Energia Atomica, 8400 Bariloche (Argentina)


    Using quantum field theory and bosonization, we determine the quantum phase diagram of the one-dimensional Hubbard model with bond-charge interaction X in addition to the usual Coulomb repulsion U at half-filling, for small values of the interactions. We show that it is essential to take into account formally irrelevant terms of order X. They generate relevant terms proportional to X{sup 2} in the flow of the renormalization group (RG). These terms are calculated using operator product expansions. The model shows three phases separated by a charge transition at U=U{sub c} and a spin transition at U=U{sub s}>U{sub c}. For UU{sub s}, the system is in the spin-density wave phase as in the usual Hubbard model. For intermediate values U{sub c}phase, which is absent in the ordinary Hubbard model with X=0. We obtain that the charge transition remains at U{sub c}=0 for X{ne}0. Solving the RG equations for the spin sector, we provide an analytical expression for U{sub s}(X). The results, with only one adjustable parameter, are in excellent agreement with numerical ones for X

  5. Spin Structures and Phase Diagrams of Extended Spatially Completely Anisotropic Triangular Lattice Antiferromagnets (United States)

    Sakakida, Keishiro; Shimahara, Hiroshi


    Motivated by recently discovered organic antiferromagnets, we examine an extended triangular lattice that consists of two types of triangles of bonds with exchange coupling constants Jℓ and J'ℓ (ℓ= 1, 2, and 3), respectively. The simplified system with Jℓ = J'ℓ > 0 is the spatially completely anisotropic triangular lattice (SCATL) antiferromagnet examined previously. The extended system, which we call an extended SCATL (ESCATL), has two different spatial anisotropy parameters J3/J2 and J'3/J'2 when J1 = J'1 is assumed. We derive classical phase diagrams and spin structures. It is found that the ESCATL antiferromagnet exhibits two up-up-down-down (uudd) phases when the imbalance of the anisotropy parameters is significant, in addition to the three Néel phases that occur in the SCATL. When the model parameters vary, these collinear phases are continuously connected by the spiral-spin phase. Using the available model parameters for the organic compounds λ-(BETS)2XCl4 (X = Fe and Ga), we examine the stabilities of the spin structures of the independent π-electron system, which is considered to primarily sustain the magnetic order, where BETS represents bis(ethylenedithio)tetraselenafulvalene. It is found that one of the uudd phases has an energy close to the ground-state energy for λ-(BETS)2FeCl4. We discuss the relevance of the magnetic anion FeCl4 and the quantum fluctuation to the magnetism of these compounds. When J'3 = 0, the system is reduced to a trellis lattice antiferromagnet. The system exhibits a stripe spiral-spin phase, which comprises one-dimensional spiral-spin states stacked alternately.

  6. Non-equilibrium Simulation of CO­2-hydrate Phase Transitions from Mixtures of CO2 and N2 Gases (United States)

    Qorbani Nashaqi, K.


    Storage of CO2 in aquifers is one of several options for reducing the emissions of CO2 to the atmosphere. Generally this option requires sealing integrity through layers of clay or shale. Many reservoirs have regions of temperature and pressure inside hydrate formation conditions. Whether hydrate formation can provide long term extra sealing still remains unverified in view of all co-existing phases that affect hydrate stability. Yet another storage option for CO2 is in the form of hydrate through exchange of in situ CH4 hydrate. Injection of CO2 into hydrate filled sediments is challenging due to the partial filling of pores with hydrate which results in low porosity and low permeability. Formation of new hydrate from injected CO2 will enhance these problems, Mixing N2 gas with the CO2 will increase permeability and will reduce driving forces for formation of new hydrate from pore water and injection gas. Hydrate can generally not reach thermodynamic equilibrium due to Gibbs' phase rule and the combined first and second laws of thermodynamics. These thermodynamic constraints on distribution of masses over co-existing phases are dynamically coupled to local mass- and heat-transport. Reservoir simulations are one possible method for investigation of possible scenarios related to injection of CO2 with N2 into aquifers containing CH4 hydrate. In this work we have developed prevoiusly modified RetrasoCodeBrite (RCB) simulator to handle injection of CO2/N2 gas mixtures. Hydrate formation and dissociation were determined by investigating Gibbs free energy differences between hydrate and hydrate formers. Gibbs free energy differences were calculated from changes in chemical potentials, which were obtained using non-equilibrium thermodynamic approach. Further extension of RCB has been implemented in this work through adding on-the-fly thermodynamic calculations. Correspondingly, hydrate phase transitions are calculated directly inside the code as a result of super

  7. Phase diagram of the spin-3/2 Blume-Capel model in three dimensions. (United States)

    Grollau, S


    We use a thermodynamically self-consistent theory to obtain the phase diagram of the ferromagnetic spin-3/2 Blume-Capel model on the simple cubic lattice. The theory is based on an Ornstein-Zernike approximation where the direct correlation function is truncated and the dependence upon the thermodynamic variables is determined by a set of two coupled partial differential equations. Within this framework, we localize the critical line in zero external field with high accuracy and in good agreement with previous Monte Carlo analysis. At low temperature, in contrast with Monte Carlo results, we find a first-order transition line ending at a critical end point whose coordinates are given by (k(B)T(c)/Jc=0.213+/-0.003,Delta(c)/Jc=0.491+/-0.001).

  8. Magnetic phase diagram of the anisotropic double-exchange model a Monte Carlo study

    CERN Document Server

    Yi, H S; Hur, N H


    The magnetic phase diagram of highly anisotropic double-exchange model systems is investigated as a function of the ratio of the anisotropic hopping integrals, i.e., t sub c /t sub a sub b , on a three-dimensional lattice by using Monte Carlo calculations. The magnetic domain structure at low temperature is found to be a generic property of the strong anisotropy region. Moreover, the t sub c /t sub a sub b ratio is crucial in determining the anisotropic charge transport due to the relative spin orientation of the magnetic domains. As a result, we show the anisotropic hopping integral is the most likely cause of the magnetic domain structure. It is noted that the competition between the reduced interlayer double-exchange coupling and the thermal frustration of the ordered two-dimensional ferromagnetic layer seems to be crucial in understanding the properties of layered manganites.

  9. Melt-gas phase equilibria and state diagrams of the selenium-tellurium system (United States)

    Volodin, V. N.; Trebukhov, S. A.; Burabaeva, N. M.; Nitsenko, A. V.


    The partial pressures of saturated vapor of the components in the Se-Te system are determined and presented in the form of temperature-concentration dependences from which the boundaries of the melt-gas phase transition are calculated at atmospheric pressure and vacuums of 2000 and 100 Pa. The existence of azeotropic mixtures is revealed. It is found that the points of inseparably boiling melts correspond to 7.5 at % of Se and 995°C at 101325 Pa, 10.9 at % at 673°C and 19.5 at % at 522°C in vacuums of 2000 and 100 Pa, respectively. A complete state diagram is constructed, including the fields of gas-liquid equilibria at atmospheric and low pressures, the boundaries of which allow us to assess the behavior of selenium and tellurium upon distillation fractionation.

  10. Magnetic phase diagram of ErNi2B2C

    DEFF Research Database (Denmark)

    Jensen, A.; Toft, K.N.; Abrahamsen, A.B.


    The magnetic phase diagram of the superconductor ErNi2B2C (T-c = 11 K and T-N = 6 K) has been studied by neutron diffraction as a function of temperature and magnetic field applied along the symmetry directions [010], [110] and [001] of the tetragonal crystal structure. A series of commensurate...... magnetic structures, consistent with a transversely polarized spin-density wave with modulation vectors Q = n/ma* (0.55 less than or equal to n/m field model that has been established from...... an analysis of bulk magnetization and zero-field neutron diffraction data. The model accounts for most of the observed features but fails to explain the occurrence of a small component Qdelta approximate to -0.005b* observed close to H-c2 when the field is applied along [110]. (C) 2004 Elsevier B.V. All...

  11. Unusual Phase Diagram of CeOs4Sb12

    Energy Technology Data Exchange (ETDEWEB)

    Ho, P. -C. [Fresno State Univ., Fresno, CA (United States); Goddard, P. A. [Warwick Univ., Coventry (United Kingdom); Maple, M. B. [Univ. of California, San Diego, CA (United States); Singleton, John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)


    Filled skutterudite compounds, with the formula MT4X12, where M is an alkali metal, alkaline-earth, lanthanide, or actinide, T is Fe, Ru, or Os, and X is P, As, or Sb, display a wide variety of interesting phenomena caused by strong electron correlations [1]. Among these, the three compounds CeOs4Sb12, PrOs4Sb12, and NdOs4Sb12, formed by employing Periodic Table neighbors for M, span the range from an antiferromagnetic (AFM) semimetal (M = Ce) via a 1.85 K unconventional (quadrupolar-fluctuation mediated) superconductor (M = Pr) to a 1 K ferromagnet (FM; M = Nd). In the course of an extended study of these compounds, we uncovered an unusual phase diagram for CeOs4Sb12.

  12. Phase diagrams of the multitrace quartic matrix models of noncommutative Φ4 theory (United States)

    Ydri, B.; Ramda, K.; Rouag, A.


    We report a direct and robust calculation, free from ergodic problems, of the nonuniform-to-uniform (stripe) transition line of noncommutative Φ24 by means of an exact Metropolis algorithm applied to the first nontrivial multitrace correction of this theory on the fuzzy sphere. In fact, we reconstruct the entire phase diagram including the Ising, matrix, and stripe boundaries together with the triple point. We also report that the measured critical exponents of the Ising transition line agrees with the Onsager values in two dimensions. The triple point is identified as a termination point of the one-cut-to-two-cut transition line and is located at (b ˜,c ˜)=(-1.55 ,0.4 ), which compares favorably with a previous Monte Carlo estimate.

  13. The solid-liquid phase diagrams of binary mixtures of even saturated fatty acids differing by six carbon atoms

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Mariana C. [LPT, Department of Chemical Process, School of Chemical Engineering, University of Campinas, UNICAMP, P.O. Box 6066, 13083-970, Campinas-SP (Brazil); EXTRAE, Department of Food Engineering, Faculty of Food Engineering, University of Campinas, UNICAMP, P.O. Box 6121, 13083-862, Campinas-SP (Brazil); CICECO, Departamento de Quimica da Universidade de Aveiro, 3810-193 Aveiro (Portugal); Rolemberg, Marlus P. [DETQI, Department of Chemical Technology, Federal University of Maranhao (UFMA), Sao Luis, Maranhao (Brazil); Meirelles, Antonio J.A. [EXTRAE, Department of Food Engineering, Faculty of Food Engineering, University of Campinas, UNICAMP, P.O. Box 6121, 13083-862, Campinas-SP (Brazil); Coutinho, Joao A.P. [CICECO, Departamento de Quimica da Universidade de Aveiro, 3810-193 Aveiro (Portugal); Kraehenbuehl, M.A., E-mail: [LPT, Department of Chemical Process, School of Chemical Engineering, University of Campinas, UNICAMP, P.O. Box 6066, 13083-970, Campinas-SP (Brazil)


    This study was aimed at using the solid-liquid phase diagrams for three binary mixtures of saturated fatty acids, especially the phase transitions below the liquidus line. These mixtures are compounded by caprylic acid (C{sub 8:0}) + myristic acid (C{sub 14:0}), capric acid (C{sub 10:0}) + palmitic acid (C{sub 16:0}), lauric acid (C{sub 12:0}) + stearic acid (C{sub 18:0}), differing by six carbon atoms between carbon chains. The phase diagrams were obtained by differential scanning calorimetry (DSC). The polarized light microscopy was used to complement the characterization for a full grasp of the phase diagram. Not only do these phase diagrams present peritectic and eutectic reactions, but also metatectic reactions, due to solid-solid phase transitions common, in fatty acids. These findings have contributed to the elucidation of the phase behavior of these important biochemical molecules with implications in various industrial production.

  14. Thermochemical and phase diagram studies of the Sn-Zn-Ni system

    Energy Technology Data Exchange (ETDEWEB)

    Gandova, V.D. [Faculty of Chemistry, University of Plovdiv, 24 Tsar Asen Str., 4000 Plovdiv (Bulgaria); Broz, P. [Masaryk University, Faculty of Science, Department of Chemistry, Kotlarska 2, 61137 Brno (Czech Republic); Bursik, J. [Institute of Physics of Materials, Academy of Sciences, Zizkova 22, 61662, Brno (Czech Republic); Vassilev, G.P., E-mail: [Faculty of Chemistry, University of Plovdiv, 24 Tsar Asen Str., 4000 Plovdiv (Bulgaria)


    Highlights: {yields} Sn-Zn-Ni phase diagram in the vicinity of the Sn-Zn system. {yields} Unidentified compositions (UX1-UX4) are repeatedly observed. {yields} This indicates up to 6 ternary compounds in the system. {yields} A ternary eutectic reaction at around 190 {sup o}C is found. - Abstract: The phase diagram Sn-Zn-Ni was studied by means of DSC and electron microprobe analysis. The samples were positioned in three isopleth sections with nickel contents of 0.04 (section 1), 0.08 (section 2) and 0.12 (section 3) mole fractions. The mole fractions of Sn corresponding to the particular sections were as follows: from 0.230 to 0.768 (section 1), from 0.230 to 0.736 (section 2); from 0.220 to 0.704 (section 3). Mixtures of pure metals were sealed under vacuum in quartz ampoules and annealed at 350 {sup o}C. The solid phases identified in the samples were: {gamma}-(i.e. Ni{sub 5}Zn{sub 21}), (Zn) and the ternary phase T1. Unidentified compositions were observed. One of them: UX1 (X{sub Ni} = 0.071 {+-} 0.005, X{sub Sn} = 0.439 {+-} 0.009 and X{sub Zn} = 0.490 {+-} 0.010) might indicate another (stable or metastable) ternary compound (T3) in the system Sn-Zn-Ni. Considering the data obtained by combining DSC with microstructure observations, the studied alloys could be divided in two groups (A and B). A ternary eutectic reaction at around 190 {sup o}C is common for the A-group alloys. The phases taking part in this reaction are, probably, Ni{sub 5}Zn{sub 21}, (Zn), ({beta}Sn) and liquid. B-group samples do not show ternary eutectic reaction and are also characterized by the presence of the ternary compound T1 (absent in the A-group alloys). Four other groups of thermal arrests were registered (TA{sub 1}-TA{sub 4}). It was found that TA{sub 2} peaks were characteristic for most of the A-group samples, while TA{sub 1} peaks were registered with all B-group samples.

  15. Phase Behaviour, Thermodynamics and Kinetics of Clathrate Hydrate Systems of Carbon Dioxide in Presence of Tetrahydrofuran and Electrolytes

    NARCIS (Netherlands)

    Mohamad Sabil, K. Bin


    In view of the possibilities for new development of carbon dioxide hydrate processes, this study focused on experimental measurements to obtain fundamental insight into the phase behaviour and the kinetic of formation of carbon dioxide hydrate forming systems. These data are essential for the

  16. Study of Monte Carlo Simulation Method for Methane Phase Diagram Prediction using Two Different Potential Models

    KAUST Repository

    Kadoura, Ahmad


    Lennard‐Jones (L‐J) and Buckingham exponential‐6 (exp‐6) potential models were used to produce isotherms for methane at temperatures below and above critical one. Molecular simulation approach, particularly Monte Carlo simulations, were employed to create these isotherms working with both canonical and Gibbs ensembles. Experiments in canonical ensemble with each model were conducted to estimate pressures at a range of temperatures above methane critical temperature. Results were collected and compared to experimental data existing in literature; both models showed an elegant agreement with the experimental data. In parallel, experiments below critical temperature were run in Gibbs ensemble using L‐J model only. Upon comparing results with experimental ones, a good fit was obtained with small deviations. The work was further developed by adding some statistical studies in order to achieve better understanding and interpretation to the estimated quantities by the simulation. Methane phase diagrams were successfully reproduced by an efficient molecular simulation technique with different potential models. This relatively simple demonstration shows how powerful molecular simulation methods could be, hence further applications on more complicated systems are considered. Prediction of phase behavior of elemental sulfur in sour natural gases has been an interesting and challenging field in oil and gas industry. Determination of elemental sulfur solubility conditions helps avoiding all kinds of problems caused by its dissolution in gas production and transportation processes. For this purpose, further enhancement to the methods used is to be considered in order to successfully simulate elemental sulfur phase behavior in sour natural gases mixtures.

  17. Neutron-diffraction studies of the nuclear magnetic phase diagram of copper

    DEFF Research Database (Denmark)

    Annila, A.J.; Clausen, Kurt Nørgaard; Oja, A.S.


    -field phase and the intermediate-field structure is of first order. The change from (0 2/3 2/3) at intermediate fields to (100) at zero field is associated with a large region (0.02 less-than-or-equal-to B less-than-or-equal-to 0.06 mT) of coexisting-(100) and (0 2/3 2/3)-type Bragg peaks, and can......We have studied the spontaneous antiferromagnetic (AF) order in the nuclear spin system of copper by use of neutron-diffraction experiments at nanokelvin temperatures. Copper is an ideal model system as a nearest-neighbor-dominated spin-3/2 fcc antiferromagnet. The phase diagram has been...... investigated by measuring the magnetic-field dependence of the (100) reflection, characteristic of a type-I AF structure, and of a Bragg peak at (0 2/3 2/3). The results suggest the presence of high-field (100) phases at 0.12 less-than-or-equal-to B less-than-or-equal-to B(c) almost-equal-to 0.26 mT, for B...

  18. Phase diagram of multiferroic KCu3As2O7(OD ) 3 (United States)

    Nilsen, Gøran J.; Simonet, Virginie; Colin, Claire V.; Okuma, Ryutaro; Okamoto, Yoshihiko; Tokunaga, Masashi; Hansen, Thomas C.; Khalyavin, Dmitry D.; Hiroi, Zenji


    The layered compound KCu3As2O7(OD ) 3 , comprising distorted kagome planes of S =1 /2 Cu2 + ions, is a recent addition to the family of type-II multiferroics. Previous zero-field neutron diffraction work has found two helically ordered regimes in KCu3As2O7(OD ) 3 , each showing a distinct coupling between the magnetic and ferroelectric order parameters. Here, we extend this work to magnetic fields up to 20 T using neutron powder diffraction, capacitance, polarization, and high-field magnetization measurements, hence determining the H -T phase diagram. We find metamagnetic transitions in both low-temperature phases around μ0Hc˜3.7 T, which neutron powder diffraction reveals to correspond to rotations of the helix plane away from the easy plane, as well as a small change in the propagation vector. Furthermore, we show that the sign of the ferroelectric polarization is reversible in a magnetic field, although no change is observed (or expected on the basis of the magnetic structure) due to the transition at 3.7 T. We finally justify the temperature dependence of the polarization in both zero-field ordered phases by a symmetry analysis of the free energy expansion, and attempt to account for the metamagnetic transition by adding anisotropic exchange interactions to our existing model for KCu3As2O7(OD ) 3 .

  19. High-Pressure High-Temperature Phase Diagram of the Organic Crystal Paracetamol (United States)

    Smith, Spencer; Montgomery, Jeffrey; Vohra, Yogesh

    High-pressure high-temperature (HPHT) Raman spectroscopy studies have been performed on the organic crystal paracetamol in a diamond anvil cell utilizing boron-doped diamond as heating anvil. The HPHT data obtained from boron-doped diamond heater is cross-checked with data obtained using a standard block heater diamond anvil cell. Isobaric measurements were conducted at pressures up to 8.5 GPa and temperature up to 520 K in a number of different experiments. Solid state phase transitions from monoclinic Form I --> orthorhombic Form II were observed at various pressures and temperatures as well as transitions from Form II --> unknown Form IV. The melting temperature for paracetamol was observed to increase with increasing pressures to 8.5 GPa. Our previous angle dispersive x-ray diffraction studies at the Advanced Photon Source has confirmed the existence of two unknown crystal structures Form IV and Form V of paracetamol at high pressure and ambient temperature. The phase transformation from Form II to Form IV occurs at ~8.5 GPa and from Form IV to Form V occurs at ~11 GPa at ambient temperature. Our new data is combined with the previous ambient temperature high-pressure Raman and X- ray diffraction data to create the first HPHT phase diagram of paracetamol. Doe-NNSA Carnegie DOE Alliance Center (CDAC) under Grant Number DE-NA0002006.

  20. Liquid part of the phase diagram and percolation line for two-dimensional Mercedes-Benz water (United States)

    Urbic, T.


    Monte Carlo simulations and Wertheim's thermodynamic perturbation theory (TPT) are used to predict the phase diagram and percolation curve for the simple two-dimensional Mercedes-Benz (MB) model of water. The MB model of water is quite popular for explaining water properties, but the phase diagram has not been reported till now. In the MB model, water molecules are modeled as two-dimensional Lennard-Jones disks, with three orientation-dependent hydrogen-bonding arms, arranged as in the MB logo. The liquid part of the phase space is explored using grand canonical Monte Carlo simulations and two versions of Wertheim's TPT for associative fluids, which have been used before to predict the properties of the simple MB model. We find that the theory reproduces well the physical properties of hot water but is less successful at capturing the more structured hydrogen bonding that occurs in cold water. In addition to reporting the phase diagram and percolation curve of the model, it is shown that the improved TPT predicts the phase diagram rather well, while the standard one predicts a phase transition at lower temperatures. For the percolation line, both versions have problems predicting the correct position of the line at high temperatures.

  1. In-focus electron microscopy of frozen-hydrated biological samples with a Boersch phase plate

    Energy Technology Data Exchange (ETDEWEB)

    Barton, B.; Rhinow, D.; Walter, A.; Schroeder, R. [Max Planck Institute of Biophysics, Max-von-Laue Str. 3, 60438 Frankfurt am Main (Germany); Benner, G.; Majorovits, E.; Matijevic, M.; Niebel, H. [Carl Zeiss NTS GmbH, D-73447 Oberkochen (Germany); Mueller, H.; Haider, M. [CEOS GmbH, Englerstr. 26, 69126 Heidleberg (Germany); Lacher, M.; Schmitz, S.; Holik, P. [Caesar Research Center, Ludwig-Erhard-Allee 2, D-53175 Bonn (Germany); Kuehlbrandt, W., E-mail: [Max Planck Institute of Biophysics, Max-von-Laue Str. 3, 60438 Frankfurt am Main (Germany)


    We report the implementation of an electrostatic Einzel lens (Boersch) phase plate in a prototype transmission electron microscope dedicated to aberration-corrected cryo-EM. The combination of phase plate, C{sub s} corrector and Diffraction Magnification Unit (DMU) as a new electron-optical element ensures minimal information loss due to obstruction by the phase plate and enables in-focus phase contrast imaging of large macromolecular assemblies. As no defocussing is necessary and the spherical aberration is corrected, maximal, non-oscillating phase contrast transfer can be achieved up to the information limit of the instrument. A microchip produced by a scalable micro-fabrication process has 10 phase plates, which are positioned in a conjugate, magnified diffraction plane generated by the DMU. Phase plates remained fully functional for weeks or months. The large distance between phase plate and the cryo sample permits the use of an effective anti-contaminator, resulting in ice contamination rates of <0.6 nm/h at the specimen. Maximal in-focus phase contrast was obtained by applying voltages between 80 and 700 mV to the phase plate electrode. The phase plate allows for in-focus imaging of biological objects with a signal-to-noise of 5-10 at a resolution of 2-3 nm, as demonstrated for frozen-hydrated virus particles and purple membrane at liquid-nitrogen temperature. -- Highlights: Black-Right-Pointing-Pointer We implement an electrostatic Boersch phase plate into a dedicated prototypical TEM. Black-Right-Pointing-Pointer Phase contrast aberration-corrected electron microscope (PACEM) includes a diffraction magnification unit (DMU). Black-Right-Pointing-Pointer DMU minimizes obstruction of low spatial frequencies by the phase plate. Black-Right-Pointing-Pointer In-focus phase contrast generation is demonstrated for frozen-hydrated biological specimens.

  2. Phase diagram with an enhanced spin-glass region of the mixed Ising-XY magnet LiHoxEr1-xF4

    DEFF Research Database (Denmark)

    Piatek, J. O.; Dalla Piazza, B.; Nikseresht, N.


    We present the experimental phase diagram of LiHoxEr1-xF4, a dilution series of dipolar-coupled model magnets. The phase diagram was determined using a combination of ac susceptibility and neutron scattering. Three unique phases in addition to the Ising ferromagnet LiHoF4 and the XY antiferromagnet...

  3. Phase Diagram and Transformations of Iron Pentacarbonyl to nm Layered Hematite and Carbon-Oxygen Polymer under Pressure (United States)

    Ryu, Young Jay; Kim, Minseob; Yoo, Choong-Shik


    We present the phase diagram of Fe(CO)5, consisting of three molecular polymorphs (phase I, II and III) and an extended polymeric phase that can be recovered at ambient condition. The phase diagram indicates a limited stability of Fe(CO)5 within a pressure-temperature dome formed below the liquid- phase II- polymer triple point at 4.2 GPa and 580 K. The limited stability, in turn, signifies the temperature-induced weakening of Fe-CO back bonds, which eventually leads to the dissociation of Fe-CO at the onset of the polymerization of CO. The recovered polymer is a composite of novel nm-lamellar layers of crystalline hematite Fe2O3 and amorphous carbon-oxygen polymers. These results, therefore, demonstrate the synthesis of carbon-oxygen polymer by compressing Fe(CO)5, which advocates a novel synthetic route to develop atomistic composite materials by compressing organometallic compounds.

  4. The Lipid domain Phase diagram in a Dipalmitoyl-PC/Docosahaexnoic Acid-PE/Cholesterol System (United States)

    Lor, Chai; Hirst, Linda


    Lipid domains in bilayer membrane and polyunsaturated fatty acids (PUFAs) are thought to play an important role in cellular activities. In particular, lipids containing docosahaexnoic acid are an interesting class of PUFAs due to their health benefits. In this project, we perform oxidation measurements of DHA-PE to determine the rate of oxidation in combination with antioxidants. A ternary diagram of DPPC/DHA-PE/cholesterol is mapped out to identify phase separation phenomena using atomic force microscope (AFM). Fluorescence microscopy is also used to image lipid domains in a flat bilayer with fluorescent labels. As expected, we observe the phase, shape, and size of lipid domains changes with varying composition. Moreover, we find that the roughness of the domains changes possibly due to overpacking of cholesterol in domains. This model study provides further understanding of the role of cholesterol in the bilayer membrane leading towards a better understanding of cell membranes. NSF award # DMR 0852791, ``CAREER: Self-Assembly of Polyunsaturated Lipids and Cholesterol In The Cell Membrane.''

  5. Investigation of phase diagrams and physical stability of drug-polymer solid dispersions. (United States)

    Lu, Jiannan; Shah, Sejal; Jo, Seongbong; Majumdar, Soumyajit; Gryczke, Andreas; Kolter, Karl; Langley, Nigel; Repka, Michael A


    Solid dispersion technology has been widely explored to improve the solubility and bioavailability of poorly water-soluble compounds. One of the critical drawbacks associated with this technology is the lack of physical stability, i.e. the solid dispersion would undergo recrystallization or phase separation thus limiting a product's shelf life. In the current study, the melting point depression method was utilized to construct a complete phase diagram for felodipine (FEL)-Soluplus® (SOL) and ketoconazole (KTZ)-Soluplus® (SOL) binary systems, respectively, based on the Flory-Huggins theory. The miscibility or solubility of the two compounds in SOL was also determined. The Flory-Huggins interaction parameter χ values of both systems were calculated as positive at room temperature (25 °C), indicating either compound was miscible with SOL. In addition, the glass transition temperatures of both solid dispersion systems were theoretically predicted using three empirical equations and compared with the practical values. Furthermore, the FEL-SOL solid dispersions were subjected to accelerated stability studies for up to 3 months.

  6. A Centrality and Event Plane Detector for STAR to Complete the Phase Diagram of Quantum Chromodynamics (United States)

    Halal, George; STAR Collaboration


    The properties of the nearly perfect liquid, Quark Gluon Plasma (QGP), which filled the universe a microsecond after the Big Bang are studied by colliding heavy-ions at relativistic energies. Our project focuses on building and testing an Event Plane Detector (EPD) for the STAR experiment and analyzing the data collected from collisions. When a minimum ionizing particle hits one of the optically-isolated tiles of this detector, which are made of scintillator plastic, it lights up. The light then travels through a wavelength-shifting fiber embedded in the tile to a clear optical fiber to be detected by silicon photo-multipliers. This detector is an improved version of the Beam-Beam Counter, which is currently at STAR. It will help us measure the centrality and event plane of collisions with more precision. Data collected will aid us in mapping out the transition phase between the QGP and hadronic matter, which evolved into the chemical elements we see today, and in searching for a unique critical point in the phase diagram of Quantum Chromodynamics matter. In 2017, a commissioning run has taken place at RHIC, colliding protons at 510 GeV and gold ions at 54.4 GeV. Some data analysis from one eighth of the EPD that is installed will also be discussed.

  7. High-throughput continuous hydrothermal synthesis of an entire nanoceramic phase diagram. (United States)

    Weng, Xiaole; Cockcroft, Jeremy K; Hyett, Geoffrey; Vickers, Martin; Boldrin, Paul; Tang, Chiu C; Thompson, Stephen P; Parker, Julia E; Knowles, Jonathan C; Rehman, Ihtesham; Parkin, Ivan; Evans, Julian R G; Darr, Jawwad A


    A novel High-Throughput Continuous Hydrothermal (HiTCH) flow synthesis reactor was used to make directly and rapidly a 66-sample nanoparticle library (entire phase diagram) of nanocrystalline Ce(x)Zr(y)Y(z)O(2-delta) in less than 12 h. High resolution PXRD data were obtained for the entire heat-treated library (at 1000 degrees C/1 h) in less than a day using the new robotic beamline I11, located at Diamond Light Source (DLS). This allowed Rietveld-quality powder X-ray diffraction (PXRD) data collection of the entire 66-sample library in <1 day. Consequently, the authors rapidly mapped out phase behavior and sintering behaviors for the entire library. Out of the entire 66-sample heat-treated library, the PXRD data suggests that 43 possess the fluorite structure, of which 30 (out of 36) are ternary compositions. The speed, quantity and quality of data obtained by our new approach, offers an exciting new development which will allow structure-property relationships to be accessed for nanoceramics in much shorter time periods.

  8. Phase changes of filled ice Ih methane hydrate under low temperature and high pressure. (United States)

    Tanaka, Takehiko; Hirai, Hisako; Matsuoka, Takahiro; Ohishi, Yasuo; Yagi, Takehiko; Ohtake, Michika; Yamamoto, Yoshitaka; Nakano, Satoshi; Irifune, Tetsuo


    Low-temperature and high-pressure experiments were performed with filled ice Ih structure of methane hydrate under 2.0-77.0 GPa and 30-300 K using diamond anvil cells and a helium-refrigeration cryostat. In situ X-ray diffractometry revealed distinct changes in the compressibility of the axial ratios of the host framework with pressure. Raman spectroscopy showed a split in the C-H vibration modes of the guest methane molecules, which was previously explained by the orientational ordering of the guest molecules. The pressure and temperature conditions at the split of the vibration modes agreed well with those of the compressibility change. The results indicate the following: (i) the orientational ordering of the guest methane molecules from an orientationally disordered state occurred at high pressures and low temperatures; and (ii) this guest ordering led to anisotropic contraction in the host framework. Such guest orientational ordering and subsequent anisotropic contraction of the host framework were similar to that reported previously for filled ice Ic hydrogen hydrate. Since phases with different guest-ordering manners were regarded as different phases, existing regions of the guest disordered-phase and the guest ordered-phase were roughly estimated by the X-ray study. In addition, above the pressure of the guest-ordered phase, another high-pressure phase developed in the low-temperature region. The deuterated-water host samples were also examined, and the influence of isotopic effects on guest ordering and phase transformation was observed.

  9. Phase Behavior of Ritonavir Amorphous Solid Dispersions during Hydration and Dissolution. (United States)

    Purohit, Hitesh S; Taylor, Lynne S


    The aim of this research was to study the interplay of solid and solution state phase transformations during the dissolution of ritonavir (RTV) amorphous solid dispersions (ASDs). RTV ASDs with polyvinylpyrrolidone (PVP), polyvinylpyrrolidone vinyl acetate (PVPVA) and hydroxypropyl methylcellulose acetate succinate (HPMCAS) were prepared at 10-50% drug loading by solvent evaporation. The miscibility of RTV ASDs was studied before and after exposure to 97% relative humidity (RH). Non-sink dissolution studies were performed on fresh and moisture-exposed ASDs. RTV and polymer release were monitored using ultraviolet-visible spectroscopy. Techniques including fluorescence spectroscopy, confocal imaging, scanning electron microscopy (SEM), atomic force microscopy (AFM), differential scanning calorimetry (DSC) and nanoparticle tracking analysis (NTA) were utilized to monitor solid and the solution state phase transformations. All RTV-PVP and RTV-PVPVA ASDs underwent moisture-induced amorphous-amorphous phase separation (AAPS) on high RH storage whereas RTV-HPMCAS ASDs remained miscible. Non-sink dissolution of PVP- and PVPVA-based ASDs at low drug loadings led to rapid RTV and polymer release resulting in concentrations in excess of amorphous solubility, liquid-liquid phase separation (LLPS) and amorphous nanodroplet formation. High drug loading PVP- and PVPVA-based ASDs did not exhibit LLPS upon dissolution as a consequence of extensive AAPS in the hydrated ASD matrix. All RTV-HPMCAS ASDs led to LLPS upon dissolution. RTV ASD dissolution is governed by a competition between the dissolution rate and the rate of phase separation in the hydrated ASD matrix. LLPS was observed for ASDs where the drug release was polymer controlled and only ASDs that remained miscible during the initial phase of dissolution led to LLPS. Techniques such as fluorescence spectroscopy, confocal imaging and SEM were useful in understanding the phase behavior of ASDs upon hydration and dissolution

  10. Understanding the bond-energy, hardness, and adhesive force from the phase diagram via the electron work function (United States)

    Lu, Hao; Huang, Xiaochen; Li, Dongyang


    Properties of metallic materials are intrinsically determined by their electron behavior. However, relevant theoretical treatment involving quantum mechanics is complicated and difficult to be applied in materials design. Electron work function (EWF) has been demonstrated to be a simple but fundamental parameter which well correlates properties of materials with their electron behavior and could thus be used to predict material properties from the aspect of electron activities in a relatively easy manner. In this article, we propose a method to extract the electron work functions of binary solid solutions or alloys from their phase diagrams and use this simple approach to predict their mechanical strength and surface properties, such as adhesion. Two alloys, Fe-Ni and Cu-Zn, are used as samples for the study. EWFs extracted from phase diagrams show same trends as experimentally observed ones, based on which hardness and surface adhesive force of the alloys are predicted. This new methodology provides an alternative approach to predict material properties based on the work function, which is extractable from the phase diagram. This work may also help maximize the power of phase diagram for materials design and development.

  11. Phase Diagram of the Bose Condensation of Interwell Excitons in GaAs/AlGaAs Double Quantum Wells

    DEFF Research Database (Denmark)

    Dremin, A. A.; Timofeev, V. B.; Larionov, A. V.


    observed in the experiment was attributed to Bose–Einstein condensation in a quasi-two-dimensional system of interwell excitons. In the temperature interval studied (0.5–3.6) K, the critical exciton density and temperature were determined and a phase diagram outlining the exciton condensate region...

  12. Quantum phase diagram of the integrable px+ipy fermionic superfluid

    DEFF Research Database (Denmark)

    Rombouts, Stefan; Dukelsky, Jorge; Ortiz, Gerardo


    We determine the zero-temperature quantum phase diagram of a px+ipy pairing model based on the exactly solvable hyperbolic Richardson-Gaudin model. We present analytical and large-scale numerical results for this model. In the continuum limit, the exact solution exhibits a third-order quantum pha...

  13. Self-trapping phase diagram for the strongly correlated extended Holstein-Hubbard model in two-dimensions (United States)

    Sankar, I. V.; Chatterjee, Ashok


    The two-dimensional extended Holstein-Hubbard model is investigated in the strong correlation regime to study the nature of self-trapping transition and the polaron phase diagram in the absence of superconductivity. Using a series of canonical transformations followed by zero-phonon averaging the extended Holstein-Hubbard model is converted into an effective extended Hubbard model which is subsequently transformed into an effective t- J model in the strong correlation limit. This effective t- J model is finally solved using the mean-field Hartree-Fock approximation to show that the self-trapping transition is continuous in the anti-adiabatic limit while it is discontinuous in the adiabatic limit. The phase diagrams for the localization-delocalization transition, namely the phase line and the phase surface separating the small polaron and large polaron states are also shown.

  14. The Computerised Calculus in the Prognosis of the Phase Equilibrium Diagram of the Ternary System Al-Cu-Si


    Florentina A. Cziple


    The paper presents a model for establishing the mathematical functions of the liquidus and solidus curves, from the binary diagrams Al-Si, Si-Cu, Cu-Al and their use in the prognosis of the phase equilibrium diagram from the ternary system Al-Cu-Si. We have studied the model of the non-ideal liquid solution of the regular type. The calculus and graphic plotting of the equations for the binary systems has been performed on the computer with the software programmes MathC...

  15. Development of a new combinatorial mask for addressable ternary phase diagramming: application to rare earth doped phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, R.; Kubota, H.; Tanigawa, T.; Murakami, M.; Yamamoto, Y.; Matsumoto, Y.; Koinuma, H


    We report on the computer-aided design of a novel mask for the addressable ternary phase diagram to serve a quick screening of multi-component functional materials. Masking patterns were optimized to make a triangular ternary diagram with each composition changed from 0 to 100% by simulating the deposition process under the condition of synchronous control of the mask motion, target exchange, and laser pulses. Fabrication of a ternary M{sub 0.01}Y{sub 1.99}O{sub 3} (M=Eu, Tm, Tb) phosphor material demonstrates of the direct mapping relationship between the film composition and its cathode luminescence (CL) property.

  16. The effect of four-spin exchanges on the honeycomb lattice diagram phase of S=3/2 J1-J2 Antiferromagnetic Heisenberg model

    Directory of Open Access Journals (Sweden)

    F Keshavarz


    Full Text Available In this study, the effect of four-spin exchanges between the nearest and next nearest neighbor spins of honeycomb lattice on the phase diagram of S=3/2 antiferomagnetic Heisenberg model is considered with two-spin exchanges between the nearest and next nearest neighbor spins. Firstly, the method is investigated with classical phase diagram. In classical phase diagram, in addition to Neel order, classical degeneracy is also seen. The existance of this phase in diagram phase is important because of the probability of the existence of quantum spin liquid in this region for such amount of interaction. To investigate the effect of quantum fluctuation on the stability of the obtained classical phase diagram, linear spin wave theory has been used. Obtained results show that in classical degeneracy regime, the quantum fluctuations cause the order by disorder in the spin system and the ground state is ordered

  17. Extended phase diagram of R NiC2 family: Linear scaling of the Peierls temperature (United States)

    Roman, Marta; Strychalska-Nowak, Judyta; Klimczuk, Tomasz; Kolincio, Kamil K.


    Physical properties for the late-lanthanide-based R NiC2 (R =Dy , Ho, Er, and Tm) ternary compounds are reported. All the compounds show antiferromagnetic ground state with the Néel temperature ranging from 3.4 K for HoNiC2 to 8.5 K for ErNiC2. The results of the transport and galvanomagnetic properties confirm a charge density wave state at and above room temperature with transition temperatures TCDW=284 , 335, 366, and 394 K for DyNiC2, HoNiC2, ErNiC2, and TmNiC2, respectively. The Peierls temperature TCDW scales linearly with the unit cell volume. A similar linear dependence has been observed for the temperature of the lock-in transition T1 as well. Beyond the intersection point of the trend lines, the lock-in transition is no longer observed. In this Rapid Communication we demonstrate an extended phase diagram for the R NiC2 family.

  18. Magnetic phase diagram of layered manganites in the highly doped regime.

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, J. F.; Ling, C. D.; Millburn, J. E.; Argyriou, D. N.; Berger, A.; Medarde, M.


    The naturally layered colossal magnetoresistive (CMR) manganites La{sub 2{minus}2x}Sr{sub 1+2x}Mn{sub 2}O{sub 7} exhibit an extremely varied range of magnetic and electronic behavior over a very narrow composition range between x = 0.3 and x = 0.5. The successful synthesis in our laboratories of compounds with nominally greater than 50 percent Mn{sup 4+} concentration has now allowed the study of this heretofore unexplored region of the phase diagram. Here we present detailed neutron diffraction measurements of these compounds with doping levels 0.5 < x <1.0. As predicted by simple theories, the type-A layered antiferromagnetic (AF) structure is found at x{approximately}0.5 and the type-G ''rocksalt'' AF structure at x = 1.0. Between these two extremes is found a C-type structure (ferromagnetic rods parallel to b coupled antiferromagnetically to all neighboring rods) stabilized by orbital ordering of y{sup 2} states. Also in this Mn{sup 4+}-rich regime is found a region in which no long-range magnetic order is observed. We discuss how semi-empirical models can explain the variety of magnetic structures and how structural trends as a function of doping corroborate the unifying notion of a shift from in-plane to axial orbital occupation as the Mn{sup 4+} concentration is decreased.

  19. Phase diagram of insulating crystal and quantum Hall states in ABC-stacked trilayer graphene (United States)

    Côté, R.; Rondeau, Maxime; Gagnon, Anne-Marie; Barlas, Yafis


    In the presence of a perpendicular magnetic field, ABC-stacked trilayer graphene's chiral band structure supports a 12-fold degenerate N=0 Landau level (LL). Along with the valley and spin degrees of freedom, the zeroth LL contains additional quantum numbers associated with the LL orbital index n=0,1,2. Remote interlayer hopping terms and external potential difference ΔB between the layers lead to LL splitting by introducing a gap ΔLL between the degenerate zero-energy triplet LL orbitals. Assuming that the spin and valley degrees of freedom are frozen, we study the phase diagram of this system resulting from competition of the single particle LL splitting and Coulomb interactions within the Hartree-Fock approximation at integer filling factors. In some range [ΔLLc,1,ΔLLc,2] of the gap ΔLL, the uniform QH state is unstable to the formation of a crystal state at integer filling factors while outside of this range, the ground state is a uniform quantum Hall state where the electrons occupy the lowest unoccupied LL orbital index. The transition between the uniform and crystal states should be characterized by a Hall plateau transition as a function of ΔLL at a fixed filling factor. We also study the properties of this crystal state and discuss its experimental detection.

  20. Construction and Validation of Binary Phase Diagram for Amorphous Solid Dispersion Using Flory-Huggins Theory. (United States)

    Bansal, Krishna; Baghel, Uttam Singh; Thakral, Seema


    Drug-polymer miscibility is one of the fundamental prerequisite for the successful design and development of amorphous solid dispersion formulation. The purpose of the present work is to provide an example of the theoretical estimation of drug-polymer miscibility and solubility on the basis of Flory-Huggins (F-H) theory and experimental validation of the phase diagram. The F-H interaction parameter, χ d-p, of model system, aceclofenac and Soluplus, was estimated by two methods: by melting point depression of drug in presence of different polymer fractions and by Hildebrand and Scott solubility parameter calculations. The simplified relationship between the F-H interaction parameter and temperature was established. This enabled us to generate free energy of mixing (ΔG mix) curves for varying drug-polymer compositions at different temperatures and finally the spinodal curve. The predicted behavior of the binary system was evaluated through X-ray diffraction, differential scanning calorimetry, and in vitro dissolution studies. The results suggest possibility of employing interaction parameter as preliminary tool for the estimation of drug-polymer miscibility.

  1. Ionic effects on the temperature-force phase diagram of DNA. (United States)

    Amnuanpol, Sitichoke


    Double-stranded DNA (dsDNA) undergoes a structural transition to single-stranded DNA (ssDNA) in many biologically important processes such as replication and transcription. This strand separation arises in response either to thermal fluctuations or to external forces. The roles of ions are twofold, shortening the range of the interstrand potential and renormalizing the DNA elastic modulus. The dsDNA-to-ssDNA transition is studied on the basis that dsDNA is regarded as a bound state while ssDNA is regarded as an unbound state. The ground state energy of DNA is obtained by mapping the statistical mechanics problem to the imaginary time quantum mechanics problem. In the temperature-force phase diagram the critical force F c (T) increases logarithmically with the Na + concentration in the range from 32 to 110 mM. Discussing this logarithmic dependence of F c (T) within the framework of polyelectrolyte theory, it inevitably suggests a constraint on the difference between the interstrand separation and the length per unit charge during the dsDNA-to-ssDNA transition.

  2. Experimental investigation of the dissolution of fractures. From early stage instability to phase diagram (United States)

    Osselin, Florian; Budek, Agnieszka; Cybulski, Olgierd; Kondratiuk, Pawel; Garstecki, Piotr; Szymczak, Piotr


    Dissolution of natural rocks is a fundamental geological process and a key part of landscape formation and weathering processes. Moreover, in current hot topics like Carbon Capture and Storage or Enhanced Oil Recovery, mastering dissolution of the host rock is fundamental for the efficiency and the security of the operation. The basic principles of dissolution are well-known and the theory of the reactive infiltration instability has been extensively studied. However, the experimental aspect has proved very challenging because of the strong dependence of the outcome with pore network, chemical composition, flow rate... In this study we are trying to tackle this issue by using a very simple and efficient device consisting of a chip of pure gypsum inserted between two polycarbonate plates and subjected to a constant flow rate of pure water. Thanks to this device, we are able to control all parameters such as flow rate, fracture aperture, roughness of the walls... but also to observe in situ the progression of the dissolution thanks to the transparency of the polycarbonate which is impossible with 3D rocks. We have been using this experimental set-up to explore and investigate all aspects of the dissolution in a fracture, such as initial instability and phase diagram of different dissolution patterns, and to compare it with theory and simulations, yielding very good agreement and interesting feedbacks on the coupling between flow and chemistry in geological media

  3. Model and phase-diagram analysis of photothermal instabilities in an optomechanical resonator (United States)

    Bigongiari, Alessandra; Ortu, Antonio; Fuso, Francesco; Arimondo, Ennio; Mannella, Riccardo; Ciampini, Donatella


    A study of the phototermal instabilities in a Fabry-Perot cavity is reported, where one mirror consists of a silicon-nitride membrane coated by the molecular organic semiconductor tris(8-hydroxyquinoline) aluminum and silver layers. We propose a theoretical model to describe the back-action associated with the delayed response of the cavity field to the radiation pressure force and the photothermal force. For the case under investigation, the photothermal force response occurs on a timescale that is comparable to that of mirror oscillations and dominates over the radiation pressure force. A phase diagram analysis has been performed to map the stability of the static solution as a function of the control parameters. The model equations are integrated numerically and the time history is compared to experimental measurements of the transmitted field and displacement of the membrane. In both experimental and theoretical data we observe large amplitude oscillations when the cavity length is scanned at a low speed compared to the growth rate of the instability. The perturbation is found to evolve through three regimes: sinusoidal oscillations, double peaks and single peaks followed by a lethargic regime. When the cavity length is scanned in opposite directions, dynamical hysteresis is observed, whose extension has a power law dependence on the scanning rate.

  4. Phase diagrams of dune shape and orientation depending on sand availability. (United States)

    Gao, Xin; Narteau, Clément; Rozier, Olivier; Courrech du Pont, Sylvain


    New evidence indicates that sand availability does not only control dune type but also the underlying dune growth mechanism and the subsequent dune orientation. Here we numerically investigate the development of bedforms in bidirectional wind regimes for two different conditions of sand availability: an erodible sand bed or a localized sand source on a non-erodible ground. These two conditions of sand availability are associated with two independent dune growth mechanisms and, for both of them, we present the complete phase diagrams of dune shape and orientation. On an erodible sand bed, linear dunes are observed over the entire parameter space. Then, the divergence angle and the transport ratio between the two winds control dune orientation and dynamics. For a localized sand source, different dune morphologies are observed depending on the wind regime. There are systematic transitions in dune shape from barchans to linear dunes extending away from the localized sand source, and vice-versa. These transitions are captured fairly by a new dimensionless parameter, which compares the ability of winds to build the dune topography in the two modes of dune orientation.

  5. Stability phase diagram of a perpendicular magnetic tunnel junction in noncollinear geometry (United States)

    Strelkov, N.; Timopheev, A.; Sousa, R. C.; Chshiev, M.; Buda-Prejbeanu, L. D.; Dieny, B.


    Experimental measurements performed on MgO-based perpendicular magnetic tunnel junctions show a strong dependence of the stability voltage-field diagrams as a function of the direction of the magnetic field with respect to the plane of the sample. When the magnetic field is applied in-plane, systematic nonlinear phase boundaries are observed for various lateral sizes. The simulation results based on the phenomenological Landau-Lifshitz-Gilbert equation including the in-plane and out-of-plane spin transfer torques are consistent with the measurements if a second-order anisotropy contribution is considered. Furthermore, performing the stability analysis in linear approximation allowed us to analytically extract the critical switching voltage at zero temperature in the presence of an in-plane field. This study indicates that in the noncollinear geometry investigations are suitable to detect the presence of the second-order term in the anisotropy. Such higher order anisotropy term can yield an easy-cone anisotropy which reduces the thermal stability factor but allows for more reproducible spin transfer torque switching due to a reduced stochasticity of the switching. As a result, the energy per write event decreases much faster than the thermal stability factor as the second-order anisotropy becomes more negative. Easy-cone anisotropy can be useful for fast-switching spin transfer torque magnetic random access memories provided the thermal stability can be maintained above the required value for a given memory specification.

  6. Studies of the QCD Phase Diagram with Heavy-Ion Collisions at J-PARC (United States)

    Sako, Hiroyuki

    To clarify phase structures in the QCD phase diagram is an ultimate goal of heavy-ion collision experiments. Studies of internal structures of neutron stars are also one of the most important topics of nuclear physics since the discovery of neutron stars with two-solar mass. For these physics goals, J-PARC heavy-ion project (J-PARC-HI) has been proposed, where extremely dense matter with 5-10 times the normal nuclear density will be created. Heavy-ion beams up to Uranium will be accelerated to 1-19 AGeV/c, with the designed world's highest beam rate of 1011 Hz. The acceleration of such high-rate beams can be realized by a new heavy-ion linac and a new booster ring, in addition to the existing 3-GeV and 50-GeV proton synchrotrons. To study the above physics goals, following physics observables will be measured in extremely high statistics expected in J-PARC-HI. To search for the critical point, high-order event-by-event fluctuations of conserved charges such as a net-baryon number, an electric charge number, and a strangeness number will be measured. To study the chiral symmetry restoration, dilepton spectra from light vector meson decays will be measured. Also, collective flows, particle correlations will be measured to study the equation of state and hyperon-hyperon and hyperon-nucleon interactions related to neutron stars. Strange quark matter (strangelet) and multi-strangeness hypernuclei will be searched for which may be related directly to the matter constituting the neutron star core. In this work, the physics goals, the experimental design, and expected physics results of J-PARC-HI will be discussed.

  7. Magnetic Hamiltonian and phase diagram of the quantum spin liquid Ca10Cr7O28 (United States)

    Balz, Christian; Lake, Bella; Nazmul Islam, A. T. M.; Singh, Yogesh; Rodriguez-Rivera, Jose A.; Guidi, Tatiana; Wheeler, Elisa M.; Simeoni, Giovanna G.; Ryll, Hanjo


    A spin liquid is a new state of matter with topological order where the spin moments continue to fluctuate coherently down to the lowest temperatures rather than develop static long-range magnetic order as found in conventional magnets. For spin liquid behavior to arise in a material the magnetic Hamiltonian must be "frustrated", where the combination of lattice geometry, interactions, and anisotropies gives rise to competing spin arrangements in the ground state. Theoretical Hamiltonians which produce spin liquids are spin ice, the Kitaev honeycomb model, and the kagome antiferromagnet. Spin liquid behavior, however, in real materials is rare because they can only approximate these Hamiltonians and often have weak higher-order terms that destroy the spin liquid state. Ca10Cr7O28 is a new quantum spin liquid candidate with magnetic Cr5 + ions that possess quantum spin number S =½ . The spins are entirely dynamic in the ground state and the excitation spectrum is broad and diffuse, as is typical of spinons which are the excitations of a spin liquid. In this paper we determine the Hamiltonian of Ca10Cr7O28 using inelastic neutron scattering under high magnetic field to induce a field-polarized paramagnetic ground state and spin-wave excitations that can be fitted to extract the interactions. We further explore the phase diagram by using inelastic neutron scattering and heat capacity measurements and establish the boundaries of the spin liquid phase as a function of magnetic field and temperature. Our results show that Ca10Cr7O28 consists of distorted kagome bilayers with several isotropic ferromagnetic and antiferromagnetic interactions where, unexpectedly, the ferromagnetic interactions are stronger than the antiferromagnetic ones. This complex Hamiltonian does not correspond to any known spin liquid model and points to new directions in the search for quantum spin liquid behavior.

  8. 25th anniversary article: exploring nanoscaled matter from speciation to phase diagrams: metal phosphide nanoparticles as a case of study. (United States)

    Carenco, Sophie; Portehault, David; Boissière, Cédric; Mézailles, Nicolas; Sanchez, Clément


    The notions of nanoscale "phase speciation" and "phase diagram" are defined and discussed in terms of kinetic and thermodynamic controls, based on the case of metal phosphide nanoparticles. After an overview of the most successful synthetic routes for these exotic nanomaterials, the cases of InP, Ni2 P, Ni12 P5 and Pdx Py are discussed in detail to highlight the relationship between composition, structure, and size at the nanoscale. The influence of morphology is discussed next by comparing the behavior of Cu3 P nanophases with those of Nix Py , FeP/Fe2 P, and CoP/Co2 P. Perspectives provide the reader with methodological guidelines for further investigation of nanoscale "phase diagrams", and their use for optimized synthesis of new functional nanomaterials. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Phase diagram of the Blume-Emery-Griffiths model on the simple cubic lattice calculated by the linear chain approximation

    CERN Document Server

    Albayrak, E


    The linear chain approximation is used to study the temperature dependence of the order parameters and the phase diagrams of the Blume-Emery-Griffiths model on the simple cubic lattice with dipole-dipole, quadrupole-quadrupole coupling strengths and a crystal-field interaction. The problem is approached introducing first a trial one-dimensional Hamiltonian whose free energy can be calculated exactly by the transfer matrix method. Then using the Bogoliubov variational principle, the free energy of the model is determined. It is assumed that the dipolar and quadrupolar intrachain coupling constants are much stronger than the corresponding interchain constants and confined the attention to the case of nearest-neighbor interactions. The phase transitions are examined and the phase diagrams are obtained for several values of the coupling strengths in the three different planes. A comparison with other approximate techniques is also made.

  10. Phase diagram of the Bi[sub 2]O[sub 3]-SrO-CaO quasiternary system

    Energy Technology Data Exchange (ETDEWEB)

    Shimpo, R.; Nakamura, Y. (Univ. of Tokyo (Japan))


    Numerous reports have been published on the superconductivity, structure, and physical properties of the Bi-Sr-Ca-Cu-O system, including the ceramic superconductors of Bi[sub 2]Sr[sub 2]Ca[sub 2]Cu[sub 3]O[sub y] and Bi[sub 2]Sr[sub 2]CaCu[sub 2]O[sub y]. On the phase diagrams of the system, numbers of studies have so far been presented, but there exist several regions in the proposed phase diagram of the Bi[sub 2]O[sub 3]-SrO-CaO quasiternary system, which have been presented by several investigators, are different from each other because the ternary system includes a number of solid solution phases of which the phase equilibrium relations are complicated. In this study, isothermal sections of the phase diagram for the Bi[sub 2]O[sub 3]-SrO-CaO ternary system at 973 and 1,023 K have been investigated. Experiments were conducted in air, because this system does not include copper oxides and, therefore, it is considered that the oxygen contents in the interceramic compounds in this system are substantially not affected by the oxygen potential.

  11. Local probe investigations of the electronic phase diagrams of iron pnictides and chalcogenides

    Energy Technology Data Exchange (ETDEWEB)

    Materne, Philipp


    In this work, the electronic phase diagrams of Ca{sub 1-x}Na{sub x}Fe{sub 2}As{sub 2} and Fe{sub 1+y}Te were investigated using muon spin relaxation and Moessbauer spectroscopy. Single crystals of Ca{sub 1-x}Na{sub x}Fe{sub 2}As{sub 2} with x = 0.00, 0.35, 0.50, and 0.67 were examined. The undoped 122 parent compound CaFe{sub 2}As{sub 2} is a semi metal and shows antiferromagnetic commensurate spin density wave order below 167 K. By hole doping via Na substitution, the magnetic order is suppressed and superconductivity emerges including a Na-substitution level region, where both phases coexist. Upon Na substitution, a tilting of the magnetic moments out of the ab-plane is found. The interaction of the magnetic and superconducting order parameter in this coexistence region was studied and a nanoscopic coexistence of both order parameters is found. This is proven by a reduction of the magnetic order parameter of 7 % in x = 0.50 below the superconducting transition temperature. This reduction was analysed using Landau theory and a systematic correlation between the reduction of the magnetic order parameter and the ratio of the transition temperatures, T{sub c}/T{sub N}, for the 122 family of the iron pnictides is presented. The magnetic phase transition is accompanied by a tetragonal-to-orthorhombic phase transition. The lattice dynamics at temperatures above and below this magneto-structural phase transition were studied and no change in the lattice dynamics were found. However, the lattice for finite x is softer than for the undoped compound. For x = 0.67, diluted magnetic order is found. Therefore, the magnetism in Ca{sub 1-x}Na{sub x}Fe{sub 2}As{sub 2} is persistent even at optimal doping. The superconducting state is investigated by measuring the temperature dependence of the magnetic penetration depth, where two superconducting gaps with a weighting of nearly 50:50 are obtained. A temperature independent anisotropy of the magnetic penetration depth γ{sub

  12. Phase diagram of a non-Abelian Aubry-André-Harper model with p -wave superfluidity (United States)

    Wang, Jun; Liu, Xia-Ji; Xianlong, Gao; Hu, Hui


    We study theoretically a one-dimensional quasiperiodic Fermi system with topological p -wave superfluidity, which can be deduced from a topologically nontrivial tight-binding model on the square lattice in a uniform magnetic field and subject to a non-Abelian gauge field. The system may be regarded as a non-Abelian generalization of the well-known Aubry-André-Harper model. We investigate its phase diagram as a function of the strength of the quasidisorder and the amplitude of the p -wave order parameter through a number of numerical investigations, including a multifractal analysis. There are four distinct phases separated by three critical lines, i.e., two phases with all extended wave functions [(I) and (IV)], a topologically trivial phase (II) with all localized wave functions, and a critical phase (III) with all multifractal wave functions. Phase (I) is related to phase (IV) by duality. It also seems to be related to phase (II) by duality. Our proposed phase diagram may be observable in current cold-atom experiments, in view of simulating non-Abelian gauge fields and topological insulators/superfluids with ultracold atoms.

  13. The extension of the phase rule to nano-systems and on the quaternary point in one-component nano phase diagrams. (United States)

    Kaptay, George


    The phase rule of Gibbs has been extended to nano-systems in this paper. For that, first the total number of atoms or stable molecules (N) in the system is selected as a new independent thermodynamic variable to characterize the size of nano-systems. N is preferred to r (the radius of the system) as the volume and radius are functions of other independent variables (p, T, composition) and therefore r is not an independent variable. As follows from the extended phase rule, the maximum number of phases and the degree of freedom at a given number of phases is increased by 1 for nano-systems compared to macro-systems, due to the new independent thermodynamic parameter N. The extended phase rule can serve as the basis to work out topological details of nano phase diagrams. As an example, an existence of a quaternary point is predicted in one component nano phase diagram of thallium (in contrast to usual one component phase diagrams with triple points at most). At given values of p = 7.2E-12 bar, T = 544 K, and N = 1.2E5, HCP (hexagonal closely packed solid), BCC (body centered cubic solid), liquid and vapour phases of pure TI are predicted to be in equilibrium.

  14. To the question of the interpolation of the phase equilibrium curves for the hydrates of methane and carbon dioxide

    Directory of Open Access Journals (Sweden)

    Musakaev Nail


    Full Text Available The experimental data base was developed. This database includes 200 points of the phase equilibrium curve of methane hydrate, as well as more than 300 experimental points for carbon dioxide hydrate. This database is based on the work of a large number of researchers. Taking into account the experimental data, empirical formulas are constructed for determining the equilibrium parameters of the methane and carbon dioxide hydrates, as well as the equilibrium curve of “liquid carbon dioxide – gaseous carbon dioxide”.

  15. Bridging and depletion mechanisms in colloid-colloid effective interactions: A reentrant phase diagram (United States)

    Fantoni, Riccardo; Giacometti, Achille; Santos, Andrés


    A general class of nonadditive sticky-hard-sphere binary mixtures, where small and large spheres represent the solvent and the solute, respectively, is introduced. The solute-solute and solvent-solvent interactions are of hard-sphere type, while the solute-solvent interactions are of sticky-hard-sphere type with tunable degrees of size nonadditivity and stickiness. Two particular and complementary limits are studied using analytical and semi-analytical tools. The first case is characterized by zero nonadditivity, lending itself to a Percus-Yevick approximate solution from which the impact of stickiness on the spinodal curves and on the effective solute-solute potential is analyzed. In the opposite nonadditive case, the solvent-solvent diameter is zero and the model can then be reckoned as an extension of the well-known Asakura-Oosawa model with additional sticky solute-solvent interaction. This latter model has the property that its exact effective one-component problem involves only solute-solute pair potentials for size ratios such that a solvent particle fits inside the interstitial region of three touching solutes. In particular, we explicitly identify the three competing physical mechanisms (depletion, pulling, and bridging) giving rise to the effective interaction. Some remarks on the phase diagram of these two complementary models are also addressed through the use of the Noro-Frenkel criterion and a first-order perturbation analysis. Our findings suggest reentrance of the fluid-fluid instability as solvent density (in the first model) or adhesion (in the second model) is varied. Some perspectives in terms of the interpretation of recent experimental studies of microgels adsorbed onto large polystyrene particles are discussed.

  16. Intermediate regime and a phase diagram of red blood cell dynamics in a linear flow (United States)

    Levant, Michael; Steinberg, Victor


    In this paper we investigate the in vitro dynamics of a single rabbit red blood cell (RBC) in a planar linear flow as a function of a shear stress σ and the dynamic viscosity of outer fluid ηo. A linear flow is a generalization of previous studies dynamics of soft objects including RBC in shear flow and is realized in the experiment in a microfluidic four-roll mill device. We verify that the RBC stable orientation dynamics is found in the experiment being the in-shear-plane orientation and the RBC dynamics is characterized by observed three RBC dynamical states, namely tumbling (TU), intermediate (INT), and swinging (SW) [or tank-treading (TT)] on a single RBC. The main results of these studies are the following. (i) We completely characterize the RBC dynamical states and reconstruct their phase diagram in the case of the RBC in-shear-plane orientation in a planar linear flow and find it in a good agreement with that obtained in early experiments in a shear flow for human RBCs. (ii) The value of the critical shear stress σc of the TU-TT(SW) transition surprisingly coincides with that found in early experiments in spite of a significant difference in the degree of RBC shape deformations in both the SW and INT states. (iii) We describe the INT regime, which is stationary, characterized by strong RBC shape deformations and observed in a wide range of the shear stresses. We argue that our observations cast doubts on the main claim of the recent numerical simulations that the only RBC spheroidal stress-free shape is capable to explain the early experimental data. Finally, we suggest that the amplitude dependence of both θ and the shape deformation parameter D on σ can be used as the quantitative criterion to determine the RBC stress-free shape.

  17. Rabi lattice models with discrete gauge symmetry: Phase diagram and implementation in trapped-ion quantum simulators (United States)

    Nevado, Pedro; Porras, Diego


    We study a spin-boson chain that exhibits a local Z2 symmetry. We investigate the quantum phase diagram of the model by means of perturbation theory, mean-field theory, and the density matrix renormalization group method. Our calculations show the existence of a first-order phase transition in the region where the boson quantum dynamics is slow compared to the spin-spin interactions. Our model can be implemented with trapped-ion quantum simulators, leading to a realization of minimal models showing local gauge invariance and first-order phase transitions.

  18. Phase equilibria in ternary (carbon dioxide + tetrahydrofuran + water) system in hydrate-forming region: Effects of carbon dioxide concentration and the occurrence of pseudo-retrograde hydrate phenomenon

    Energy Technology Data Exchange (ETDEWEB)

    Sabil, Khalik M. [Delft University of Technology, Laboratory of Process Equipment, Mechanical, Maritime and Materials Eng, Leeghwaterstraat 44, 2628 CA Delft (Netherlands); Chemical Engineering Programme, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia); Witkamp, Geert-Jan [Delft University of Technology, Laboratory of Process Equipment, Mechanical, Maritime and Materials Eng, Leeghwaterstraat 44, 2628 CA Delft (Netherlands); Peters, Cor J., E-mail: C.J.Peters@tudelft.n [Delft University of Technology, Laboratory of Process Equipment, Mechanical, Maritime and Materials Eng, Leeghwaterstraat 44, 2628 CA Delft (Netherlands); Chemical Engineering Programme, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia); The Petroleum Institute, Chemical Engineering Program, Bu Hasa Building, Room 2203, P.O. Box 2203, Abu Dhabi (United Arab Emirates)


    In the present work, the three- and four-phase hydrate equilibria of (carbon dioxide (CO{sub 2}) + tetrahydrofuran (THF) + water) system are measured by using Cailletet equipment in the temperature and pressure range of (272 to 292) K and (1.0 to 7.5) MPa, respectively, at different CO{sub 2} concentration. Throughout the study, the concentration of THF is kept constant at 5 mol% in the aqueous solution. In addition, the fluid phase transitions of L{sub W}-L{sub V}-V -> L{sub W}-L{sub V} (bubble point) and L{sub W}-L{sub V}-V -> L{sub W}-V (dew point) are determined when they are present in the ternary system. For comparison, the three-phase hydrate equilibria of binary (CO{sub 2} + H{sub 2}O) are also measured. Experimental measurements show that the addition of THF as a hydrate promoter extends hydrate stability region by elevating the hydrate equilibrium temperature at a specified pressure. The three-phase equilibrium line H-L{sub W}-V is found to be independent of the overall concentration of CO{sub 2}. Contradictory, at higher pressure, the phase equilibria of the systems are significantly influenced by the overall concentration of CO{sub 2} in the systems. A liquid-liquid phase split is observed at overall concentration of CO{sub 2} as low as 3 mol% at elevated pressure. The region is bounded by the bubble-points line (L{sub W}-L{sub V}-V -> L{sub W}-L{sub V}), dew points line (L{sub W}-L{sub V}-V -> L{sub W} + V) and the four-phase equilibrium line (H + L{sub W} + L{sub V} + V). At higher overall concentration of CO{sub 2} in the ternary system, experimental measurements show that pseudo-retrograde behaviour exists at pressure between (2.5 and 5) MPa at temperature of 290.8 K.

  19. A tool for modelling of microsegregation: an approximation method for partition coefficients in experimentally determined multicomponent phase diagrams

    Energy Technology Data Exchange (ETDEWEB)

    Roosz, A.; Szoeke, J. [Miskolc Univ. (Hungary). Dept. of Materials Science; Rettenmayr, M. [Darmstadt Univ. of Technology (Germany). Materials Science Dept.


    A complete set of partition coefficients of all alloying elements in multicomponent systems is an essential input for solidification models. An approximation method for partition coefficients in experimentally determined phase diagrams has been developed. The equilibria of the binary boundary systems and the eutectic valleys are used as a basis for the approximation in ternary systems. The method has been verified by a comparison of approximated and known (calculated by the CALPHAD method) partition coefficients in the Al-Cu-Si system. The ratio of the end points of calculated tie-lines is in excellent agreement with approximated partition coefficients. In the empirical Al-Cu-Si phase diagram, the approximated partition coefficients yield solid concentrations that are close to the measured solidus surface. (orig.)

  20. Superconductivity of the filled skuterrudite PrOs{sub 4}Sb{sub 12}: Phase diagram and characterisations

    Energy Technology Data Exchange (ETDEWEB)

    Measson, M.-A. [Departement de Recherche Fondamentale sur la Matiere Condensee, SPSMS, CEA Grenoble, 38054 Grenoble (France)]. E-mail:; Brison, J.P. [Centre de Recherches sur les Tres Basses Temperatures, CNRS, 25 avenue des Martyrs, BP166, 38042 Grenoble Cedex (France)]. E-mail:; Seyfarth, G. [Centre de Recherches sur les Tres Basses Temperatures, CNRS, 25 avenue des Martyrs, BP166, 38042 Grenoble Cedex (France); Braithwaite, D. [Departement de Recherche Fondamentale sur la Matiere Condensee, SPSMS, CEA Grenoble, 38054 Grenoble (France); Lapertot, G. [Departement de Recherche Fondamentale sur la Matiere Condensee, SPSMS, CEA Grenoble, 38054 Grenoble (France); Salce, B. [Departement de Recherche Fondamentale sur la Matiere Condensee, SPSMS, CEA Grenoble, 38054 Grenoble (France); Flouquet, J. [Departement de Recherche Fondamentale sur la Matiere Condensee, SPSMS, CEA Grenoble, 38054 Grenoble (France); Lhotel, E. [Centre de Recherches sur les Tres Basses Temperatures, CNRS, 25 avenue des Martyrs, BP166, 38042 Grenoble Cedex (France); Paulsen, C. [Centre de Recherches sur les Tres Basses Temperatures, CNRS, 25 avenue des Martyrs, BP166, 38042 Grenoble Cedex (France); Sugawara, H. [Department of Physics, Tokyo Metropolitan University, Minami-Ohsawa 1-1, Hashioji, Tokyo 192-0397 (Japan); Sato, H. [Department of Physics, Tokyo Metropolitan University, Minami-Ohsawa 1-1, Hashioji, Tokyo 192-0397 (Japan); Canfield, P.C. [Ames Laboratory Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States); Izawa, K. [Institute for Solid State Physics, University of Tokyo, Kashiwanoha 5-1-5 Kashiwa, Chiba 277-8581 (Japan); Matsuda, Y. [Institute for Solid State Physics, University of Tokyo, Kashiwanoha 5-1-5 Kashiwa, Chiba 277-8581 (Japan)


    We present a precise (H-T) phase diagram of the double superconducting transition in the specific heat of the heavy fermion superconductor PrOs{sub 4}Sb{sub 12}, down to 350mK, on a sample which exhibits two sharp distinct anomalies at T{sub c1}=1.89K and T{sub c2}=1.72K. Comparison with an existing phase diagram based on transport measurements will be reviewed. The intrinsic or extrinsic nature of this double transition is discussed in light of some characterisations of the superconducting transition of different samples and with respect to the historical case of UPt{sub 3}. Finally, we give a detailed analysis of H{sub c2} which shows the importance of the multiband character of the electronic structure of PrOs{sub 4}Sb{sub 12} and gives strong support to an even parity order parameter.

  1. Phase equilibria of H{sub 2}SO{sub 4}, HNO{sub 3}, and HCl hydrates and the composition of polar stratospheric clouds

    Energy Technology Data Exchange (ETDEWEB)

    Wooldridge, P.J.; Zhang, R.; Molina, M.J. [Massachusetts Institute of Technology, Cambridge, MA (United States)] [and others


    Thermodynamic properties and phase equilibria behavior for the hydrates and coexisting pairs of hydrates of common acids which exist in the stratosphere are assembled from new laboratory measurements and standard literature data. The analysis focuses upon solid-solid-vapor equilibria at temperatures around 200 K and includes new calorimetric and vapor pressure data. Calculated partial pressures versus 1/T slopes for the hydrates and coexisting hydrates agree well with experimental data where available. 42 refs., 5 figs., 4 tabs.

  2. Multiple spin-flop phase diagram of BaCu{sub 2}Si{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Glazkov, V N; Zheludev, A [Laboratorium fuer Festkoerperphysik, ETH Zurich, 8093 Zuerich (Switzerland); Dhalenne, G; Revcolevschi, A, E-mail: [Laboratoire de Physico-Chimie de l' Etat Solide, Universite Paris-Sud, 91405 Orsay Cedex (France)


    The quasi-one-dimensional compound BaCu{sub 2}Si{sub 2}O{sub 7} demonstrates numerous spin-reorientation transitions both for a magnetic field applied along the easy axis of magnetization and a magnetic field applied perpendicular to it. The magnetic phase diagram for all three principal orientations is obtained by magnetization and specific heat measurements. Values of all critical fields and low-temperature values of magnetization jumps are determined for all transitions.

  3. Ground-state phase diagram of an anisotropic spin-1/2 model on the triangular lattice (United States)

    Luo, Qiang; Hu, Shijie; Xi, Bin; Zhao, Jize; Wang, Xiaoqun


    Motivated by a recent experiment on the rare-earth material YbMgGaO4 [Y. Li et al., Phys. Rev. Lett. 115, 167203 (2015), 10.1103/PhysRevLett.115.167203], which found that the ground state of YbMgGaO4 is a quantum spin liquid, we study the ground-state phase diagram of an anisotropic spin-1 /2 model that was proposed to describe YbMgGaO4. Using the density matrix renormalization-group method in combination with the exact-diagonalization method, we calculate a variety of physical quantities, including the ground-state energy, the fidelity, the entanglement entropy and spin-spin correlation functions. Our studies show that in the quantum phase diagram, there is a 120∘ phase and two distinct stripe phases. The transitions from the two stripe phases to the 120∘ phase are of the first order. However, the transition between the two stripe phases is not of the first order, which is different from its classical counterpart. Additionally, we find no evidence for a quantum spin liquid in this model. Our results suggest that additional terms may also be important to model the material YbMgGaO4. These findings will stimulate further experimental and theoretical works in understanding the quantum spin-liquid ground state in YbMgGaO4.

  4. In-focus electron microscopy of frozen-hydrated biological samples with a Boersch phase plate. (United States)

    Barton, B; Rhinow, D; Walter, A; Schröder, R; Benner, G; Majorovits, E; Matijevic, M; Niebel, H; Müller, H; Haider, M; Lacher, M; Schmitz, S; Holik, P; Kühlbrandt, W


    We report the implementation of an electrostatic Einzel lens (Boersch) phase plate in a prototype transmission electron microscope dedicated to aberration-corrected cryo-EM. The combination of phase plate, C(s) corrector and Diffraction Magnification Unit (DMU) as a new electron-optical element ensures minimal information loss due to obstruction by the phase plate and enables in-focus phase contrast imaging of large macromolecular assemblies. As no defocussing is necessary and the spherical aberration is corrected, maximal, non-oscillating phase contrast transfer can be achieved up to the information limit of the instrument. A microchip produced by a scalable micro-fabrication process has 10 phase plates, which are positioned in a conjugate, magnified diffraction plane generated by the DMU. Phase plates remained fully functional for weeks or months. The large distance between phase plate and the cryo sample permits the use of an effective anti-contaminator, resulting in ice contamination rates of frozen-hydrated virus particles and purple membrane at liquid-nitrogen temperature. Copyright © 2011 Elsevier B.V. All rights reserved.

  5. Direct phase coexistence molecular dynamics study of the phase equilibria of the ternary methane-carbon dioxide-water hydrate system. (United States)

    Michalis, Vasileios K; Tsimpanogiannis, Ioannis N; Stubos, Athanassios K; Economou, Ioannis G


    Molecular dynamics simulation is used to predict the phase equilibrium conditions of a ternary hydrate system. In particular, the direct phase coexistence methodology is implemented for the determination of the three-phase coexistence temperature of the methane-carbon dioxide-water hydrate system at elevated pressures. The TIP4P/ice, TraPPE-UA and OPLS-UA forcefields for water, carbon dioxide and methane respectively are used, in line with our previous studies of the phase equilibria of the corresponding binary hydrate systems. The solubility in the aqueous phase of the guest molecules of the respective binary and ternary systems is examined under hydrate-forming conditions, providing insight into the predictive capability of the methodology as well as the combination of these forcefields to accurately describe the phase behavior of the ternary system. The three-phase coexistence temperature is calculated at 400, 1000 and 2000 bar for two compositions of the methane-carbon dioxide mixture. The predicted values are compared with available calculations with satisfactory agreement. An estimation is also provided for the fraction of the guest molecules in the mixed hydrate phase under the conditions examined.

  6. On the solid–liquid phase diagrams of binary mixtures of even saturated fatty alcohols: Systems exhibiting peritectic reaction

    Energy Technology Data Exchange (ETDEWEB)

    Carareto, Natália D.D. [EXTRAE, Department of Food Engineering, Food Engineering Faculty, University of Campinas, UNICAMP, CEP 13083-862 Campinas, SP (Brazil); Santos, Adenílson O. dos [Social Sciences, Health and Technology Center, University of Maranhão, UFMA, CEP 65900-410 Imperatriz, MA (Brazil); Rolemberg, Marlus P. [Institute of Science and Technology, University of Alfenas, UNIFAL, Rodovia José AurélioVilela, CEP 37715400 Poços de Caldas, MG (Brazil); Cardoso, Lisandro P. [Institute of Physics GlebWataghin, University of Campinas, UNICAMP, C.P. 6165, CEP 13083-970 Campinas, SP (Brazil); Costa, Mariana C. [School of Applied Science, University of Campinas, UNICAMP, CEP 13484-350 Limeira, SP (Brazil); Meirelles, Antonio J.A., E-mail: [EXTRAE, Department of Food Engineering, Food Engineering Faculty, University of Campinas, UNICAMP, CEP 13083-862 Campinas, SP (Brazil)


    Highlights: • SLE of binary mixtures of saturated fatty alcohols was studied. • Experimental data were obtained using DSC and stepscan DSC. • Microscopy and X-ray diffraction used as complementary techniques. • Systems presented eutectic, peritectic and metatectic points. - Abstract: The solid–liquid phase diagrams of the following binary mixtures of even saturated fatty alcohols are reported in the literature for the first time: 1-octanol (C8OH) + 1-decanol (C10OH), 1-decanol + 1-dodecanol (C12OH), 1-dodecanol + 1-hexadecanol (C16OH) and 1-tetradecanol (C14OH) + 1-octadecanol (C18OH). The phase diagrams were obtained by differential scanning calorimetry (DSC) using a linear heating rate of 1 K min{sup −1} and further investigated by using a stepscan DSC method. X-ray diffraction (XRD) and polarized light microscopy were also used to complement the characterization of the phase diagrams which have shown a complex global behavior, presenting not only peritectic and eutectic reactions, but also the metatectic reaction and partial immiscibility on solid state.

  7. Gold–Copper Nano-Alloy, “Tumbaga”, in the Era of Nano: Phase Diagram and Segregation (United States)


    Gold–copper (Au–Cu) phases were employed already by pre-Columbian civilizations, essentially in decorative arts, whereas nowadays, they emerge in nanotechnology as an important catalyst. The knowledge of the phase diagram is critical to understanding the performance of a material. However, experimental determination of nanophase diagrams is rare because calorimetry remains quite challenging at the nanoscale; theoretical investigations, therefore, are welcomed. Using nanothermodynamics, this paper presents the phase diagrams of various polyhedral nanoparticles (tetrahedron, cube, octahedron, decahedron, dodecahedron, rhombic dodecahedron, truncated octahedron, cuboctahedron, and icosahedron) at sizes 4 and 10 nm. One finds, for all the shapes investigated, that the congruent melting point of these nanoparticles is shifted with respect to both size and composition (copper enrichment). Segregation reveals a gold enrichment at the surface, leading to a kind of core–shell structure, reminiscent of the historical artifacts. Finally, the most stable structures were determined to be the dodecahedron, truncated octahedron, and icosahedron with a Cu-rich core/Au-rich surface. The results of the thermodynamic approach are compared and supported by molecular-dynamics simulations and by electron-microscopy (EDX) observations. PMID:25338111

  8. An Excel Macro to Plot the HFE-Diagram to Identify Sea Water Intrusion Phases. (United States)

    Giménez-Forcada, Elena; Sánchez San Román, F Javier


    A hydrochemical facies evolution diagram (HFE-D) is a multirectangular diagram, which is a useful tool in the interpretation of sea water intrusion processes. This method note describes a simple method for generating an HFE-D plot using the spreadsheet software package, Microsoft Excel. The code was applied to groundwater from the alluvial coastal plain of Grosseto (Tuscany, Italy), which is characterized by a complex salinization process in which sea water mixes with sulfate or bicarbonate recharge water. © 2014, National GroundWater Association.

  9. Phase diagram of Script N = 4 super-Yang-Mills theory with R-symmetry chemical potentials (United States)

    Yamada, Daisuke; Yaffe, Laurence G.


    The phase diagram of large Nc, weakly-coupled Script N = 4 supersymmetric Yang-Mills theory on a three-sphere with non-zero chemical potentials is examined. In the zero coupling limit, a transition line in the μ-T plane is found, separating a ``confined'' phase in which the Polyakov loop has vanishing expectation value from a ``deconfined'' phase in which this order parameter is non-zero. For non-zero but weak coupling, perturbative methods may be used to construct a dimensionally reduced effective theory valid for sufficiently high temperature. If the maximal chemical potential exceeds a critical value, then the free energy becomes unbounded below and no genuine equilibrium state exists. However, the deconfined plasma phase remains metastable, with a lifetime which grows exponentially with Nc (not Nc2). This metastable phase persists with increasing chemical potential until a phase boundary, analogous to a spinodal decomposition line, is reached. Beyond this point, no long-lived locally stable quasi-equilibrium state exists. The resulting picture for the phase diagram of the weakly coupled theory is compared with results believed to hold in the strongly coupled limit of the theory, based on the AdS/CFT correspondence and the study of charged black hole thermodynamics. The confinement/deconfinement phase transition at weak coupling is in qualitative agreement with the Hawking-Page phase transition in the gravity dual of the strongly coupled theory. The black hole thermodynamic instability line may be the counterpart of the spinodal decomposition phase boundary found at weak coupling, but no black hole tunneling instability, analogous to the instability of the weakly coupled plasma phase is currently known.

  10. Studies of nuclei under the extreme conditions of density, temperature, isospin asymmetry and the phase diagram of hadronic matter

    Energy Technology Data Exchange (ETDEWEB)

    Mekjian, Aram [Rutgers Univ., Piscataway, NJ (United States). Dept. of Physics and Astronomy


    The main emphasis of the entire project is on issues having to do with medium energy and ultra-relativistic energy and heavy ion collisions. A major goal of both theory and experiment is to study properties of hot dense nuclear matter under various extreme conditions and to map out the phase diagram in density or chemical potential and temperature. My studies in medium energy nuclear collisions focused on the liquid-gas phase transition and cluster yields from such transitions. Here I developed both the statistical model of nuclear multi-fragmentation and also a mean field theory.

  11. Phase diagram of a generalized off-diagonal Aubry–André model with p-wave pairing (United States)

    Liu, Tong; Wang, Pei; Chen, Shu; Xianlong, Gao


    Off-diagonal Aubry–André (AA) model has recently attracted a great deal of attention as they provide condensed matter realization of topological phases. We numerically study a generalized off-diagonal AA model with p-wave superfluid pairing in the presence of both commensurate and incommensurate hopping modulations. The phase diagram as functions of the modulation strength of incommensurate hopping and the strength of the p-wave pairing is obtained by using the multifractal analysis. We show that with the appearance of the p-wave pairing, the system exhibits mobility-edge phases and critical phases with various number of topologically-protected zero-energy modes. Predicted topological nature of these exotic phases can be realized in a cold atomic system of incommensurate bichromatic optical lattice with induced p-wave superfluid pairing by using a Raman laser in proximity to a molecular Bose–Einstein condensation.

  12. Third Law of Thermodynamics and The Shape of the Phase Diagram for Systems With a First-Order Quantum Phase Transition. (United States)

    Kirkpatrick, T R; Belitz, D


    The third law of thermodynamics constrains the phase diagram of systems with a first-order quantum phase transition. For a zero conjugate field, the coexistence curve has an infinite slope at T=0. If a tricritical point exists at T>0, then the associated tricritical wings are perpendicular to the T=0 plane, but not to the zero-field plane. These results are based on the third law and basic thermodynamics only, and are completely general. As an explicit example we consider the ferromagnetic quantum phase transition in clean metals, where a first-order quantum phase transition is commonly observed.

  13. The Computerised Calculus in the Prognosis of the Phase Equilibrium Diagram of the Ternary System Al-Cu-Si

    Directory of Open Access Journals (Sweden)

    Florentina A. Cziple


    Full Text Available The paper presents a model for establishing the mathematical functions of the liquidus and solidus curves, from the binary diagrams Al-Si, Si-Cu, Cu-Al and their use in the prognosis of the phase equilibrium diagram from the ternary system Al-Cu-Si. We have studied the model of the non-ideal liquid solution of the regular type. The calculus and graphic plotting of the equations for the binary systems has been performed on the computer with the software programmes MathCad 2000 Professional, Statistica 5, Curve Expert, and for the ternary system Al-Cu-Si, with the 3D StudioMax software

  14. Ground-state phase diagram of an (S, S') = (1, 2) spin-alternating chain with competing single-ion anisotropies

    Energy Technology Data Exchange (ETDEWEB)

    Tonegawa, T [Department of Mechanical Engineering, Fukui University of Technology, Fukui 910-8505 (Japan); Okamoto, K [Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551 (Japan); Sakai, T [Japan Atomic Energy Agency (JAEA), Spring-8, Hyogo 679-5148 (Japan); Kaburagi, M, E-mail: [Graduate School of Intercultural Studies, Kobe University, Kobe 657-8501 (Japan)


    Employing various numerical methods, we determine the ground-state phase diagram of an (S, S') = (1, 2) spin-alternating chain with antiferromagnetic nearest-neighboring exchange interactions and uniaxial single-ion anisotropies. The resulting phase diagram consists of eight kinds of phases including two phases which accompany the spontaneous breaking of the translational symmetry and a ferrimagnetic phase in which the ground-state magnetization varies continuously with the uniaxial single-ion anisotropy constants for the S=1 and S =2 spins. The appearance of these three phases is attributed to the competition between the uniaxial single-ion anisotropies of both spins.

  15. Interaction of tantalum, chromium, and phosphorus at 1070 K: Phase diagram and structural chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Lomnytska, Ya. [Ivan Franko National University of Lviv, Kyryla and Mefodiya Street 6, UA-79005 Lviv (Ukraine); Babizhetskyy, V., E-mail: [Ivan Franko National University of Lviv, Kyryla and Mefodiya Street 6, UA-79005 Lviv (Ukraine); Oliynyk, A. [Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2 (Canada); Toma, O. [Laboratory MOLTECH – Anjou, UMR-CNRS 6200, University of Angers, 49045 Angers (France); Dzevenko, M. [Ivan Franko National University of Lviv, Kyryla and Mefodiya Street 6, UA-79005 Lviv (Ukraine); Mar, A. [Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2 (Canada)


    The phase diagram of Ta–Cr–P at 1070 K has been constructed. • New ternary compounds Ta{sub 0.92(2)}Cr{sub 0.08(2)}P{sub 2} and Ta{sub 0.93(3)}Ti{sub 0.07(3)}P{sub 2} were established. • Ta{sub 1.0−0.8}Cr{sub 1.0−1.2}P and Ta{sub 0.86+x}Ti{sub 0.15-x}P{sub 2}(x= 0−0.07) exhibit homogeneity ranges. • The binary compounds reveal homogeneity ranges by Ta/Cr and Cr/Ta substitutions.

  16. Natural Gas Hydrate Phase Equilibria and Kinetics : Understanding the State-Of-The-Art Équilibres des phases des hydrates de gaz naturel et cinétique

    Directory of Open Access Journals (Sweden)

    Sloan E. D.


    Full Text Available An overview is given of gas hydrate phase equilibria and kinetics. It is suggested that with only a few exceptions hydrate phase equilibrium conditions may be predicted with acceptable accuracy for industrial purposes via the current state-of-the art. Hydrate research is at a milestone, going beyond equilibrium experiments to time-dependent measurements, such as in the kinetic arena, where there is a severe paucity of date. To illustrate the concepts, two qualitative microscopic models are presented :1 the hydrate guest: cavity size ratio and2 the dissolution of apolar molecules in liquid water. Hypotheses for macroscopic phase equilibria and kinetic nucleation phenomena are given, based upon the two models. Cet article présente brièvement les équilibres des phases des hydrates de gaz naturel et leur cinétique. Il signale qu'en l'état actuel des connaissances, les conditions d'équilibre des phases des hydrates peuvent être connues, à quelques exceptions près, avec une précision acceptable dans un but industriel. La recherche sur les hydrates atteint un point décisif, elle dépasse les expériences d'équilibre et s'intéresse aux mesures variant en fonction du temps, celles de la cinétique par exemple, où les données sont particulièrement rares. Pour illustrer le concept deux modèles qualitatifs microscopiques sont présentés : 1 le rapport de grosseur hydrate hôte/cavité, et 2 la dissolution des molécules apolaires dans l'eau liquide. L'auteur émet des hypothèses relatives aux phénomènes macroscopiques d'équilibres des phases et de nucléation cinétique, basées sur ces deux modèles.

  17. Determining the three-phase coexistence line in methane hydrates using computer simulations (United States)

    Conde, M. M.; Vega, C.


    Molecular dynamics simulations have been performed to estimate the three-phase (solid hydrate-liquid water-gaseous methane) coexistence line for the water-methane binary mixture. The temperature at which the three phases are in equilibrium was determined for three different pressures, namely, 40, 100, and 400 bar by using direct coexistence simulations. In the simulations water was described by using either TIP4P, TIP4P/2005, or TIP4P/Ice models and methane was described as simple Lennard-Jones interaction site. Lorentz-Berthelot combining rules were used to obtain the parameters of the cross interactions. For the TIP4P/2005 model positive deviations from the energetic Lorentz-Berthelot rule were also considered to indirectly account for the polarization of methane when introduced in liquid water. To locate the three-phase coexistence point, two different global compositions were used, which yielded (to within statistical uncertainty) the same predictions for the three-phase coexistence temperatures, although with a somewhat different time evolution. The three-phase coexistence temperatures obtained at different pressures when using the TIP4P/Ice model of water were in agreement with the experimental results. The main reason for this is that the TIP4P/Ice model reproduces the melting point of ice Ih.

  18. Examination of Cement Pastes Hydrated Phases, and Synthetic Products by X-Ray Diffraction (United States)


    F. E. Jones, Hydration of Calcium Aluminates and Ferrites , Fourth International Symposium on the Chemistry of Cement, Washington, D. C., 1960, Vol 1...hydrated calcium aluminates and ferrites , Proc Fifth Inte-national Symposium on the Chemistry of Cement, Tokyo, 1968, 196-. pp 37-67; discussion by M. H...water-cement ratio contained ettringite, tetracalcium aluminate inonos-2;irate-12-hydrate, calcium hydroxide, calcium silicate hydrate gel, and

  19. Mapping the phase diagram for neon to a quantum Lennard-Jones fluid using Gibbs ensemble simulations. (United States)

    Georgescu, Ionuţ; Brown, Sandra E; Mandelshtam, Vladimir A


    In order to address the issue of whether neon liquid in coexistence with its gas phase can be mapped to a quantum Lennard-Jones (LJ) fluid, we perform a series of simulations using Gibbs ensemble Monte Carlo for a range of de Boer quantum parameters Λ=ℏ/(σ√(mε)). The quantum effects are incorporated by implementing the variational gaussian wavepacket method, which provides an efficient numerical framework for estimating the quantum density at thermal equilibrium. The computed data for the LJ liquid is used to produce its phase diagram as a function of the quantum parameter, 0.065 ≤ Λ ≤ 0.11. These data are then used to fit the experimental phase diagram for neon liquid. The resulting parameters, ε = 35.68 ± 0.03 K and σ = 2.7616 ± 0.0005 Å (Λ = 0.0940), of the LJ pair potential are optimized to best represent liquid neon in coexistence with its gas phase for a range of physically relevant temperatures. This multi-temperature approach towards fitting and assessing a pair-potential is much more consistent than merely fitting a single data point, such as a melting temperature or a second virial coefficient.

  20. Magnetic phase diagram of multiferroic delafossite CuFe{sub 1-y}Ga{sub y}O{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Terada, N; Kitazawa, H [National Institute for Materials Science, Tsukuba, Ibaraki, Japan 305-0047 (Japan); Nakajima, T; Mitsuda, S, E-mail: terada.noriki@nims.go.j [Department of Physics, Faculty of Science, Tokyo University of Science, Tokyo 162-8601 (Japan)


    We report magnetic susceptibility measurements on nonmagnetic impurity-doped multiferroic CuFe{sub 1-y}Ga{sub y}O{sub 2} with 0 <= y <= 0:08. The temperature versus Ga concentration magnetic phase diagram was obtained. Comparing the presently obtained phase diagram of CuFe{sub 1-y}Ga{sub y}O{sub 2} with that of CuFe{sub 1-x}Al{sub x}O{sub 2}, we find that the stability of 4SL ground state for substitution of nonmagnetic ions does not depend on the nonmagnetic ionic radius significantly. On the other hand, the FEIC phase in CuFe{sub 1-y}Ga{sub y}O{sub 2} exists in a wider region of 0:02 <= y <= 0:05 than CuFe{sub 1-x}Al{sub x}O{sub 2}. We thus find that the local lattice distortion caused by large difference in ionic radii between Al3{sup +} and Fe3{sup +} affects the stability of the FEIC phase for nonmagnetic ion substitution significantly.

  1. Non-classical phase diagram for virus bacterial coevolution mediated by clustered regularly interspaced short palindromic repeats. (United States)

    Han, Pu; Deem, Michael W


    CRISPR is a newly discovered prokaryotic immune system. Bacteria and archaea with this system incorporate genetic material from invading viruses into their genomes, providing protection against future infection by similar viruses. The condition for coexistence of prokaryots and viruses is an interesting problem in evolutionary biology. In this work, we show an intriguing phase diagram of the virus extinction probability, which is more complex than that of the classical predator-prey model. As the CRISPR incorporates genetic material, viruses are under pressure to evolve to escape recognition by CRISPR. When bacteria have a small rate of deleting spacers, a new parameter region in which bacteria and viruses can coexist arises, and it leads to a more complex coexistence patten for bacteria and viruses. For example, when the virus mutation rate is low, the virus extinction probability changes non-montonically with the bacterial exposure rate. The virus and bacteria coevolution not only alters the virus extinction probability, but also changes the bacterial population structure. Additionally, we show that recombination is a successful strategy for viruses to escape from CRISPR recognition when viruses have multiple proto-spacers, providing support for a recombination-mediated escape mechanism suggested experimentally. Finally, we suggest that the re-entrant phase diagram, in which phages can progress through three phases of extinction and two phases of abundance at low spacer deletion rates as a function of exposure rate to bacteria, is an experimentally testable phenomenon. © 2017 The Author(s).

  2. Measurements of modulated lamellar Pβ' phases of interacting lipid membranes (United States)

    Wack, Daniel C.; Webb, Watt W.


    A diffraction study of lattice constants in the Pβ' (``rippled'') phase of hydrated lecithins suggests that the lamellar modulation arises from a delicate interplay between the energies associated with membrane curvature and with hydration, as modified by interactions between membranes. Our results imply the existence of a Lifshitz point in the global phase diagram of the lecithin-water system.

  3. The piston-cylinder apparatus for in-situ structural investigations of high-pressure phases of gas hydrates with the use of synchrotron radiation

    CERN Document Server

    Mirinski, D S; Larionova, E G; Kurnosov, A V; Ancharov, A I; Dyadin, Y A; Tolochko, B P; Sheromov, M A


    The piston-cylinder apparatus for the investigation of high-pressure gas hydrate phases by the powder diffraction method is presented. The first results concerning the nature of the high-pressure gas hydrate phase in the sulfur hexafluoride-water system are reported.

  4. Phase Diagrams of Three-Dimensional Anderson and Quantum Percolation Models Using Deep Three-Dimensional Convolutional Neural Network (United States)

    Mano, Tomohiro; Ohtsuki, Tomi


    The three-dimensional Anderson model is a well-studied model of disordered electron systems that shows the delocalization-localization transition. As in our previous papers on two- and three-dimensional (2D, 3D) quantum phase transitions [" xlink:type="simple">J. Phys. Soc. Jpn. 85, 123706 (2016)," xlink:type="simple">86, 044708 (2017)], we used an image recognition algorithm based on a multilayered convolutional neural network. However, in contrast to previous papers in which 2D image recognition was used, we applied 3D image recognition to analyze entire 3D wave functions. We show that a full phase diagram of the disorder-energy plane is obtained once the 3D convolutional neural network has been trained at the band center. We further demonstrate that the full phase diagram for 3D quantum bond and site percolations can be drawn by training the 3D Anderson model at the band center.

  5. Liquid gallium-lead mixture phase diagram, surface tension near the critical mixing point, and prewetting transition. (United States)

    Osman, S M; Grosdidier, B; Ali, I; Abdellah, A Ben


    Quite recently, we reported a semianalytical equation of state (EOS) for the Ga-Pb alloy [Phys. Rev. B 78, 024205 (2008)], which was based on the first-order perturbation theory of fluid mixtures, within the simplified random phase approximation, in conjunction with the Grosdidier et al. model pair potentials for Ga-Ga and Pb-Pb with a suitable nonadditive pair potential between Ga-Pb unlike pairs. In the present work, we employ the present EOS to calculate the Ga-Pb phase diagram along the immiscibility gap region. The accuracy of the EOS is tested by consulting the empirical binodal curve. A statistical-mechanical-based theory for the surface tension is employed to obtain an analytical expression for the alloy surface tension. We calculated the surface tension along the bimodal curve and at extreme conditions of temperatures and pressures. The surface tension exhibits reasonably well the prewetting transition of Pb atoms at the surface of the Ga-rich liquid alloy and could qualitatively explain the prewetting phenomena occurring in the Ga-rich side of the phase diagram. The predicted prewetting line and wetting temperature qualitatively agree with the empirical measurements.

  6. Conduvtivity, NMR, Thermal Measurements and Phase Diagram of the K2S2O7-KHSO4 System

    DEFF Research Database (Denmark)

    Eriksen, Kim Michael; Fehrmann, Rasmus; Hatem, Gerard


    .94. The conductivities of the solid and molten K2S2O7-KHSO4 system were measured at 13 different compositions in the whole composition range, X(KHSO4)= 0-1. The conductivity of the molten mixtures were fitted to polynomia of the second degree.The results indicated delocalization of the conducting ions compared......The phase diagram of the catalytically important K2S2O7-KHSO4 molten salt solvent system has been investigated by electrochemical, thermal and spectroscopic methods.It is of the simple eutectic type with a temperature of fusion of 205C for the eutectic composition, X(KHSO4)= 0...

  7. Hg sub 2x (CuIn) sub 1-x Se sub 2 alloys: phase diagram and lattice parameter values

    Energy Technology Data Exchange (ETDEWEB)

    Grima Gallardo, P. (Physique des Milieux Condenses, Univ. Pierre et Marie Curie, 75 - Paris (France))


    Polycrystalline samples of Hg{sub 2x}(CuIn){sub 1-x}Se{sub 2} alloys are prepared by the melt and anneal technique. Differential thermal analysis (DTA) measurements are carried out on the alloys and the T(x) diagram is determined. Debye-Scherrer X-ray photographs are used to determine equilibrium conditions and lattice parameter values. It is found that single phase solid solutions occur at all values of composition. Experimental data for the chalcopyrite-zincblende transition temperature line are compared with an extension of Rincon's model for the order-disorder transition temperature in chalcopyrites. The agreement is notable. (orig.).

  8. Effect of surfactant and surfactant blends on pseudoternary phase diagram behavior of newly synthesized palm kernel oil esters

    Directory of Open Access Journals (Sweden)

    Mahdi ES


    Full Text Available Elrashid Saleh Mahdi1, Mohamed HF Sakeena1, Muthanna F Abdulkarim1, Ghassan Z Abdullah1,3, Munavvar Abdul Sattar2, Azmin Mohd Noor11Department of Pharmaceutical Technology, 2Department of Physiology, School of Pharmaceutical Sciences, Universiti Sains Malaysia, Minden, Penang, Malaysia; 3Department of Pharmaceutical Technology, International Medical University, Bukit Jalil, Kuala Lumpur, MalaysiaBackground: The purpose of this study was to select appropriate surfactants or blends of surfactants to study the ternary phase diagram behavior of newly introduced palm kernel oil esters.Methods: Nonionic surfactant blends of Tween® and Tween®/Span® series were screened based on their solubilization capacity with water for palm kernel oil esters. Tween® 80 and five blends of Tween® 80/Span® 80 and Tween® 80/Span® 85 in the hydrophilic-lipophilic balance (HLB value range of 10.7–14.0 were selected to study the phase diagram behavior of palm kernel oil esters using the water titration method at room temperature.Results: High solubilization capacity was obtained by Tween® 80 compared with other surfactants of Tween® series. High HLB blends of Tween® 80/Span® 85 and Tween® 80/Span® 80 at HLB 13.7 and 13.9, respectively, have better solubilization capacity compared with the lower HLB values of Tween® 80/Span® 80. All the selected blends of surfactants were formed as water-in-oil microemulsions, and other dispersion systems varied in size and geometrical layout in the triangles. The high solubilization capacity and larger areas of the water-in-oil microemulsion systems were due to the structural similarity between the lipophilic tail of Tween® 80 and the oleyl group of the palm kernel oil esters.Conclusion: This study suggests that the phase diagram behavior of palm kernel oil esters, water, and nonionic surfactants is not only affected by the HLB value, but also by the structural similarity between palm kernel oil esters and the surfactant

  9. Geometric thermal phase diagrams for studying the thermal dynamic stability of hollow gold nanoballs at different temperatures. (United States)

    Jiang, Luyun; Sun, Wei; Gao, Yajun; Zhao, Jianwei


    Thermal stability is one of the main concerns for the synthesis of hollow nanoparticles. In this work, molecular dynamics simulation gave an insight into the atomic reconstruction and energy evolution during the collapse of hollow gold nanoballs, based on which a mechanism was proposed. The stability was found to depend on temperature, its wall thickness and aspect ratio to a great extent. The relationship among these three factors was revealed in geometric thermal phase diagrams (GTPDs). The GTPDs were studied theoretically, and the boundary between different stability regions can be fitted and calculated. Therefore, the GTPDs at different temperatures can be deduced and used as a guide for hollow structure synthesis.

  10. The Effect of Deformation Defect of the Shear Modulus of a Lubricant on the Boundary Friction Phase Diagram (United States)

    Lyashenko, I. A.; Manko, N. N.


    An analysis of an ultrathin lubricant layer squeezed between two atomically-smooth solid surfaces during their reciprocal motion is performed. Considering the deformation defect of the shear modulus, the effect of additive fluctuations of stress, strain, and temperature on melting of the lubricating material is investigated. The influence of the system parameters of the phase diagram is investigated for the case where the temperature intensity noise and the friction surface temperature control the regions of dry, liquid and stick-slip friction. The plots of effective potential and probability distribution are constructed as a function of stress, whose form controls the mode of friction.

  11. Simulation of Few Bifurcation Phase Diagrams of Belousov-Zhabotinsky Reaction with Eleven Variable Chaotic Model in CSTR

    Directory of Open Access Journals (Sweden)

    B. Swathi


    Full Text Available Simulation of the Gyorgyi, Rempe and Field eleven variable chaotic model in CSTR [Continuously Stirred Tank Reactor] is performed with respect to the concentrations of malonic acid and [Ce(III]. These simulation studies show steady state, periodic and non-periodic regions. These studies have been presented as two variable bifurcation phase diagrams. We also have observed the bursting phenomenon under different set of constraints. We have given much importance on computer simulation work but not included the experimental methods in this paper.

  12. Phase diagram of the hexagonal lattice quantum dimer model: Order parameters, ground-state energy, and gaps (United States)

    Schlittler, Thiago M.; Mosseri, Rémy; Barthel, Thomas


    The phase diagram of the quantum dimer model on the hexagonal (honeycomb) lattice is computed numerically, extending on earlier work by Moessner, Sondhi, and Chandra. The different ground state phases are studied in detail using several local and global observables. In addition, we analyze imaginary-time correlation functions to determine ground state energies as well as gaps to the first excited states. This leads in particular to a confirmation that the intermediary so-called plaquette phase is gapped. On the technical side, we describe an efficient world-line quantum Monte Carlo algorithm with improved cluster updates that increase acceptance probabilities by taking account of potential terms of the Hamiltonian during the cluster construction. The Monte Carlo simulations are supplemented with variational computations.

  13. Phase diagram of the two-dimensional 16-band d-p model for iron-based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Yanagi, Y., E-mail: [Department of Physics, Niigata University, Ikarashi, Niigata 950-2181 (Japan); Yamakawa, Y. [Department of Physics, Niigata University, Ikarashi, Niigata 950-2181 (Japan); Ono, Y. [Department of Physics, Niigata University, Ikarashi, Niigata 950-2181 (Japan); Center for Transdisciplinary, Research, Niigata University, Ikarashi, Niigata 950-2181 (Japan)


    The electronic state of the Fe{sub 2}As{sub 2} plane in iron-based superconductors is investigated on the basis of the two-dimensional 16-band d-p model. Using the random phase approximation for the on-site Coulomb interaction between Fe d electrons, we obtain the phase diagram including the magnetic ordered states and the superconductivity. It is found that the s{sub {+-}-}wave superconductivity, where the gap functions have different signs between the electron pockets and the hole pockets, is realized near the incommensurate magnetic ordered phase with q{approx}({pi},{pi}). The absolute values of the gap functions on the Fermi surfaces are almost isotropic but largely depend on the energy bands.

  14. Structural phase transition and phase diagram of half doped organometallic compound [(CH3)2NH2]Mn0.5Ni0.5(HCOO)3 (United States)

    Chakraborty, Tirthankar; Swain, Diptikanta; Yadav, Ruchika; Row, T. N. Guru; Elizabeth, Suja


    Structural phase transition in half doped compound [(CH3)2NH2]Mn0.5Ni0.5(HCOO)3 is investigated. Differential scanning calorimetry data indicated this to be a distinct transition with enthalpy 465.6 J/mol. Powder X-ray diffraction at different temperature shows structural phase transition from trigonal R-3c to monoclinic Cc through co-existing mixed phase. Based on the experimental results, a phase diagram has been proposed. This phase transition is confirmed to be of first order nature by specific heat measurement. Entropy change and latent heat of the phase transition are also calculated from specific heat which are found to be 2.53 J/mol-K and 412 J/mol respectively.


    NARCIS (Netherlands)



    The liquid-phase hydration of cyclohexene, a pseudo first order reversible reaction catalyzed by a strong acid ion exchange resin, macroporous Amberlite XE 307, was investigated in solvent mixtures of water and sulfolane. A decrease by a factor of 3 and 6 is observed in the experimentally measured

  16. Hydration-Induced Phase Separation in Amphiphilic Polymer Matrices and its Influence on Voclosporin Release

    Energy Technology Data Exchange (ETDEWEB)

    Khan, I. John [The State Univ. of New Jersey, Piscataway, NJ (United States); Murthy, N. Sanjeeva [The State Univ. of New Jersey, Piscataway, NJ (United States); Kohn, Joachim [The State Univ. of New Jersey, Piscataway, NJ (United States)


    Voclosporin is a highly potent, new cyclosporine -- a derivative that is currently in Phase 3 clinical trials in the USA as a potential treatment for inflammatory diseases of the eye. Voclosporin represents a number of very sparingly soluble drugs that are difficult to administer. It was selected as a model drug that is dispersed within amphiphilic polymer matrices, and investigated the changing morphology of the matrices using neutron and x-ray scattering during voclosporin release and polymer resorption. The hydrophobic segments of the amphiphilic polymer chain are comprised of desaminotyrosyl-tyrosine ethyl ester (DTE) and desaminotyrosyl-tyrosine (DT), and the hydrophilic component is poly(ethylene glycol) (PEG). Water uptake in these matrices resulted in the phase separation of hydrophobic and hydrophilic domains that are a few hundred Angstroms apart. These water-driven morphological changes influenced the release profile of voclosporin and facilitated a burst-free release from the polymer. No such morphological reorganization was observed in poly(lactide-co-glycolide) (PLGA), which exhibits an extended lag period, followed by a burst-like release of voclosporin when the polymer was degraded. An understanding of the effect of polymer composition on the hydration behavior is central to understanding and controlling the phase behavior and resorption characteristics of the matrix for achieving long-term controlled release of hydrophobic drugs such as voclosporin.

  17. The role of intermolecular interactions in the prediction of the phase equilibria of carbon dioxide hydrates (United States)

    Costandy, Joseph; Michalis, Vasileios K.; Tsimpanogiannis, Ioannis N.; Stubos, Athanassios K.; Economou, Ioannis G.


    The direct phase coexistence methodology was used to predict the three-phase equilibrium conditions of carbon dioxide hydrates. Molecular dynamics simulations were performed in the isobaric-isothermal ensemble for the determination of the three-phase coexistence temperature (T3) of the carbon dioxide-water system, at pressures in the range of 200-5000 bar. The relative importance of the water-water and water-guest interactions in the prediction of T3 is investigated. The water-water interactions were modeled through the use of TIP4P/Ice and TIP4P/2005 force fields. The TraPPE force field was used for carbon dioxide, and the water-guest interactions were probed through the modification of the cross-interaction Lennard-Jones energy parameter between the oxygens of the unlike molecules. It was found that when using the classic Lorentz-Berthelot combining rules, both models fail to predict T3 accurately. In order to rectify this problem, the water-guest interaction parameters were optimized, based on the solubility of carbon dioxide in water. In this case, it is shown that the prediction of T3 is limited only by the accuracy of the water model in predicting the melting temperature of ice.

  18. Experimental Study of the Al-Mg-Sr Phase Diagram at 400°C

    Directory of Open Access Journals (Sweden)

    D. Kevorkov


    Full Text Available The Al-Mg-Sr system is experimentally studied at 400°C using EPMA and XRD techniques. It was determined that the intermetallic phases in the Al-Mg-Sr system have a tendency to form extended substitutional solid solutions. Two ternary phases were found in this system. Solubility limits of binary and ternary phases were determined and the phase equilibria among phases were established. The isothermal section of the Al-Mg-Sr system at 400°C has been constructed using results of the phase analysis and experimental literature data.

  19. Binary Phase Diagrams and Thermodynamic Properties of Silicon and Essential Doping Elements (Al, As, B, Bi, Ga, In, N, P, Sb and Tl) (United States)

    Mostafa, Ahmad; Medraj, Mamoun


    Fabrication of solar and electronic silicon wafers involves direct contact between solid, liquid and gas phases at near equilibrium conditions. Understanding of the phase diagrams and thermochemical properties of the Si-dopant binary systems is essential for providing processing conditions and for understanding the phase formation and transformation. In this work, ten Si-based binary phase diagrams, including Si with group IIIA elements (Al, B, Ga, In and Tl) and with group VA elements (As, Bi, N, P and Sb), have been reviewed. Each of these systems has been critically discussed on both aspects of phase diagram and thermodynamic properties. The available experimental data and thermodynamic parameters in the literature have been summarized and assessed thoroughly to provide consistent understanding of each system. Some systems were re-calculated to obtain a combination of the best evaluated phase diagram and a set of optimized thermodynamic parameters. As doping levels of solar and electronic silicon are of high technological importance, diffusion data has been presented to serve as a useful reference on the properties, behavior and quantities of metal impurities in silicon. This paper is meant to bridge the theoretical understanding of phase diagrams with the research and development of solar-grade silicon production, relying on the available information in the literature and our own analysis. PMID:28773034

  20. Binary Phase Diagrams and Thermodynamic Properties of Silicon and Essential Doping Elements (Al, As, B, Bi, Ga, In, N, P, Sb and Tl). (United States)

    Mostafa, Ahmad; Medraj, Mamoun


    Fabrication of solar and electronic silicon wafers involves direct contact between solid, liquid and gas phases at near equilibrium conditions. Understanding of the phase diagrams and thermochemical properties of the Si-dopant binary systems is essential for providing processing conditions and for understanding the phase formation and transformation. In this work, ten Si-based binary phase diagrams, including Si with group IIIA elements (Al, B, Ga, In and Tl) and with group VA elements (As, Bi, N, P and Sb), have been reviewed. Each of these systems has been critically discussed on both aspects of phase diagram and thermodynamic properties. The available experimental data and thermodynamic parameters in the literature have been summarized and assessed thoroughly to provide consistent understanding of each system. Some systems were re-calculated to obtain a combination of the best evaluated phase diagram and a set of optimized thermodynamic parameters. As doping levels of solar and electronic silicon are of high technological importance, diffusion data has been presented to serve as a useful reference on the properties, behavior and quantities of metal impurities in silicon. This paper is meant to bridge the theoretical understanding of phase diagrams with the research and development of solar-grade silicon production, relying on the available information in the literature and our own analysis.

  1. Segregation of receptor-ligand complexes in cell adhesion zones: phase diagrams and the role of thermal membrane roughness (United States)

    Różycki, B.; Lipowsky, R.; Weikl, T. R.


    The adhesion zone of immune cells, the 'immunological synapse', exhibits characteristic domains of receptor-ligand complexes. The domain formation is probably caused by a length difference of the receptor-ligand complexes, and has been investigated in experiments in which T cells adhere to supported membranes with anchored ligands. For supported membranes with two types of anchored ligands, MHCp and ICAM1, which bind to the T-cell receptor (TCR) and the receptor LFA1 in the cell membrane, the coexistence of domains of the TCR-MHCp and LFA1-ICAM1 complexes in the cell adhesion zone has been observed for a wide range of ligand concentrations and affinities. For supported membranes with long and short ligands that bind to the same cell receptor CD2, in contrast, domain coexistence has been observed for a quite narrow ratio of ligand concentrations. In this paper, we determine detailed phase diagrams for cells adhering to supported membranes with a statistical-physical model of cell adhesion. We find a characteristic difference between the adhesion scenarios in which two types of ligands in a supported membrane bind (i) to the same cell receptor or (ii) to two different cell receptors, which helps us to explain the experimental observations. Our phase diagrams fully include thermal shape fluctuations of the cell membranes on nanometer scales, which lead to a critical point for the domain formation and to a cooperative binding of the receptors and ligands.

  2. Phase diagram of interfacial growth modes by vapor deposition and its application for ZnO nanostructures (United States)

    Shu, Da-Jun; Xiong, Xiang; Liu, Ming; Wang, Mu


    Interfacial growth from vapor has been extensively studied. However, a straightforward picture of the growth mode under different growth conditions is still lacking. In this paper, we develop a comprehensive interfacial growth theory based on the stochastic approach. Using a critical interisland separation, we construct a general phase diagram of the growth modes. It has been revealed that if the Ehrlich-Schwoebel barrier EES is smaller than a critical value, the interfacial growth proceeds in a layer-by-layer (LBL) mode at any deposition rate. However, if EES is larger than the critical value, LBL growth occurs only at very small or very large deposition rates relative to the intralayer hopping rate, and multilayer (ML) growth occurs at a moderate deposition rate. Experiments with zinc oxide growth by chemical vapor deposition have been designed to qualitatively demonstrate the theoretical model. By changing the flux of the carrier gas (nitrogen gas) in chemical vapor deposition, we realize LBL, ML, and then reentrance of LBL homoepitaxial growth of ZnO successively. Moreover, we find that surface kinetics of ZnO is suppressed by decreasing oxygen partial pressure by comparing the experimental observations and theoretical models, which is supported by our recent first-principles calculations. Since the influence of the substrate and the growth species on growth can approximately be represented by binding energy and surface kinetics, we suggest that the phase diagram is essential for interfacial growth of different materials by vapor deposition.

  3. Optical measurements of the phase diagrams of Langmuir monolayers of fatty acid, ester, and alcohol mixtures by Brewster-angle microscopy (United States)

    Teer, Ellis; Knobler, Charles M.; Lautz, Carsten; Wurlitzer, Stefan; Kildae, John; Fischer, Thomas M.


    Surface pressure-temperature phase diagrams have been determined by Brewster-angle microscopy for Langmuir monolayers of heneicosanoic acid with the esters methyl and ethyl heneicosanoate and octadecanoic acid with methyl, ethyl, and propyl octadecanoate. The behavior is similar to that found previously in mixtures of an acid and an alcohol. In each case with increasing ester concentration the L2/L2' phase boundary moves toward lower pressure and higher temperature while the L2/Ov boundary moves toward lower pressure and lower temperature. The L2' and Ov phases eventually merge and the boundary with the L2 phase moves to zero pressure. The phase diagram of eicosyl acetate is similar to that of the fatty acids. We attribute the variations in the diagrams to the extent of hydrogen bonding between the head group and the subphase.

  4. High-pressure phase diagram of the drug mitotane in compressed and/or supercritical CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Favareto, Rogerio [Department of Chemical Engineering, State University of Maringa (UEM), Av. Colombo, 5790, Bloco D-90, 87020-900 Maringa, PR (Brazil); Pereira, Jose R.D. [Department of Physique, State University of Maringa (UEM), Av. Colombo, 5790, Bloco G-56, 87020-900 Maringa, PR (Brazil); Santana, Cesar C. [College of Chemical Engineering, State University of Campinas (UNICAMP), Cx. Postal 6066, 13083-970 Campinas, SP (Brazil); Madureira, Ed H. [College of Veterinary Medicine and Zootechny, University of Sao Paulo (USP), Av. Duque de Caxias Norte, 225, 13635-900 Pirassununga, SP (Brazil); Cabral, Vladimir F. [Department of Chemical Engineering, State University of Maringa (UEM), Av. Colombo, 5790, Bloco D-90, 87020-900 Maringa, PR (Brazil); Tavares, Frederico W. [School of Chemical, Federal University of Rio de Janeiro (UFRJ), Cidade Universitaria, Ilha do Fundao, 21949-900 Rio de Janeiro, RJ (Brazil); Cardozo-Filho, Lucio, E-mail: cardozo@deq.uem.b [Department of Chemical Engineering, State University of Maringa (UEM), Av. Colombo, 5790, Bloco D-90, 87020-900 Maringa, PR (Brazil)


    This work provides experimental phase diagram of mitotane, a drug used in the chemotherapy treatment of adrenocortical carcinoma, in compressed and/or supercritical CO{sub 2}. The synthetic-static method in a high-pressure variable-volume view cell coupled with a transmitted-light intensity probe was used to measure the solid-fluid (SF) equilibrium data. The phase equilibrium experiments were determined in temperature ranging from (298.2 to 333.1) K and pressure up to 22 MPa. Peng-Robinson equation of state (PR-EoS) with classical mixing rule was used to correlate the experimental data. Excellent agreement was found between experimental and calculated values.

  5. Impact of Intragranular Substructure Parameters on the Forming Limit Diagrams of Single-Phase B.C.C. Steels

    Directory of Open Access Journals (Sweden)

    Gérald Franz


    Full Text Available An advanced elastic-plastic self-consistent polycrystalline model, accounting for intragranular microstructure development and evolution, is coupled with a bifurcation-based localization criterion and applied to the numerical investigation of the impact of microstructural patterns on ductility of single-phase steels. The proposed multiscale model, taking into account essential microstructural aspects, such as initial and induced textures, dislocation densities, and softening mechanisms, allows us to emphasize the relationship between intragranular microstructure of B.C.C. steels and their ductility. A qualitative study in terms of forming limit diagrams for various dislocation networks, during monotonic loading tests, is conducted in order to analyze the impact of intragranular substructure parameters on the formability of single-phase B.C.C. steels.


    Energy Technology Data Exchange (ETDEWEB)

    R.E. Rogers


    DOE Contract DE-AC26-97FT33203 studied feasibility of utilizing the natural-gas storage property of gas hydrates, so abundantly demonstrated in nature, as an economical industrial process to allow expanded use of the clean-burning fuel in power plants. The laboratory work achieved breakthroughs: (1) Gas hydrates were found to form orders of magnitude faster in an unstirred system with surfactant-water micellar solutions. (2) Hydrate particles were found to self-pack by adsorption on cold metal surfaces from the micellar solutions. (3) Interstitial micellar-water of the packed particles were found to continue forming hydrates. (4) Aluminum surfaces were found to most actively collect the hydrate particles. These laboratory developments were the bases of a conceptual design for a large-scale process where simplification enhances economy. In the design, hydrates form, store, and decompose in the same tank in which gas is pressurized to 550 psi above unstirred micellar solution, chilled by a brine circulating through a bank of aluminum tubing in the tank employing gas-fired refrigeration. Hydrates form on aluminum plates suspended in the chilled micellar solution. A low-grade heat source, such as 110 F water of a power plant, circulates through the tubing bank to release stored gas. The design allows a formation/storage/decomposition cycle in a 24-hour period of 2,254,000 scf of natural gas; the capability of multiple cycles is an advantage of the process. The development costs and the user costs of storing natural gas in a scaled hydrate process were estimated to be competitive with conventional storage means if multiple cycles of hydrate storage were used. If more than 54 cycles/year were used, hydrate development costs per Mscf would be better than development costs of depleted reservoir storage; above 125 cycles/year, hydrate user costs would be lower than user costs of depleted reservoir storage.

  7. Phase diagram and dynamics of Rydberg-dressed fermions in two dimensions (United States)

    Khasseh, Reyhaneh; Abedinpour, Saeed H.; Tanatar, B.


    We investigate the ground-state properties and the collective modes of a two-dimensional two-component Rydberg-dressed Fermi liquid in the dipole-blockade regime. We find instability of the homogeneous system toward phase-separated and density ordered phases, using the Hartree-Fock and random-phase approximations, respectively. The spectral weight of collective density oscillations in the homogenous phase also signals the emergence of density-wave instability. We examine the effect of exchange hole on the density-wave instability and on the collective-mode dispersion using the Hubbard local-field factor.

  8. 600 °C isothermal section of the Al–Cr–Zn ternary phase diagram

    Energy Technology Data Exchange (ETDEWEB)

    He, Zuxin [School of Materials Science and Engineering, Changzhou University, 213164 Jiangsu (China); Jiangsu Key Laboratory of Material Surface Science and Technology, Changzhou University, 213164 Jiangsu (China); Jiangsu Collaborative Innovation Center of Photovolatic Science and Engineering, Changzhou University, 213164 Jiangsu (China); Su, Xuping, E-mail: [School of Materials Science and Engineering, Changzhou University, 213164 Jiangsu (China); Jiangsu Key Laboratory of Material Surface Science and Technology, Changzhou University, 213164 Jiangsu (China); Jiangsu Collaborative Innovation Center of Photovolatic Science and Engineering, Changzhou University, 213164 Jiangsu (China); Peng, Haoping; Liu, Ya; Wu, Changjun; Wang, Jianhua [School of Materials Science and Engineering, Changzhou University, 213164 Jiangsu (China); Jiangsu Key Laboratory of Material Surface Science and Technology, Changzhou University, 213164 Jiangsu (China)


    600 °C isothermal section of the Al–Cr–Zn system has been determined by Scanning Electron Microscopy-Energy Dispersive X-ray spectrometry (SEM-EDS), and X-ray Diffraction (XRD). Eleven three-phase regions have been identified experimentally at 600 °C. The τ{sub 3} and τ{sub 4} ternary compounds were identified in this isothermal section and the crystal structures of both phases are cubic. The lattice parameters of τ{sub 3} and τ{sub 4} are a = 2.1536 nm and a = 1.8323 nm, respectively. The formerly reported τ{sub 1} phase was not found. The formerly reported τ{sub 2} phase is an extension of Al{sub 7}Cr. The highest Zn content in γ{sub 2} and ν phases is 7.1 at at.% and 6.7 at.%, respectively. The Zn solubility in Al{sub 7}Cr phase can be up to 10.4 at.%, while that in Al{sub 4}Cr phase is less than 4 at.%. The clearly phase relation of the Al–Cr–Zn system can lead us to better understand the effect of Cr on the corrosion behavior of metals in the Zn–Al bath and the Hot-dip galvanizing process. - Highlights: • Isothermal section of the Al–Cr–Zn system at 600 °C was determined. • Eleven three-phase regions were identified experimentally at 600 °C. • Existence of the γ{sub 2} and ν phases was confirmed at 600 °C. • X-ray diffraction patterns of the ternary phases τ{sub 3} and τ{sub 4} were proposed for the first time.

  9. Phase diagram of the system Ca–Ti–O at 1200 K

    Indian Academy of Sciences (India)

    Phase relations in the system Ca–Ti–O have been established by equilibration of several samples at 1200 K for prolonged periods and identification of phases in quenched samples by optical and scanning electron microscopy, XRD and EDS. Samples representing 20 compositions in the ternary system were analyzed.

  10. Phase diagrams of mixtures of a polymer and a cholesteric liquid crystal under an external field. (United States)

    Matsuyama, Akihiko


    We present a mean field theory to describe phase behaviors in mixtures of a polymer and a cholesteric liquid crystal under an external magnetic or electric field. Taking into account a chiral coupling between a polymer and a liquid crystal under the external field, we examine twist-untwist phase transitions and phase separations in the mixtures. It is found that a cholesteric-nematic phase transition can be induced by not only the external field but also concentration and temperature. Depending on the strength of the external field, we predict cholesteric-paranematic (Ch+pN), nematic-paranematic (N+pN), cholesteric-nematic (Ch+N) phase separations, etc., on the temperature-concentration plane. We also discuss mixtures of a non-chiral nematic liquid crystal and a chiral dopant.

  11. Decreased stability of methane hydrates in marine sediments owing to phase-boundary roughness. (United States)

    Wood, W T; Gettrust, J F; Chapman, N R; Spence, G D; Hyndman, R D


    Below water depths of about 300 metres, pressure and temperature conditions cause methane to form ice-like crystals of methane hydrate. Marine deposits of methane hydrate are estimated to be large, amassing about 10,000 gigatonnes of carbon, and are thought to be important to global change and seafloor stability, as well as representing a potentially exploitable energy resource. The extent of these deposits can usually be inferred from seismic imaging, in which the base of the methane hydrate stability zone is frequently identifiable as a smooth reflector that runs parallel to the sea floor. Here, using high-resolution seismic sections of seafloor sediments in the Cascadia margin off the coast of Vancouver Island, Canada, we observe lateral variations in the base of the hydrate stability zone, including gas-rich vertical intrusions into the hydrate stability zone. We suggest that these vertical intrusions are associated with upward flow of warmer fluids. Therefore, where seafloor fluid expulsion and methane hydrate deposits coincide, the base of the hydrate stability zone might exhibit significant roughness and increased surface area. Increased area implies that significantly more methane hydrate lies close to being unstable and hence closer to dissociation in the event of a lowering of pressure due to sea-level fall.

  12. Structure and phase diagram of nucleosome core particles aggregated by multivalent cations. (United States)

    Bertin, Aurélie; Mangenot, Stéphanie; Renouard, Madalena; Durand, Dominique; Livolant, Françoise


    The degree of compaction of the eukaryotic chromatin in vivo and in vitro is highly sensitive to the ionic environment. We address the question of the effect of multivalent ions on the interactions and mutual organization of the chromatin structural units, the nucleosome core particles (NCPs). Conditions of precipitation of NCPs in the presence of 10 mM Tris buffer and various amounts of either magnesium (Mg(2+)) or spermidine (Spd(3+)) are explored, compared, and discussed in relation to theoretical models. In addition, the structure of the aggregates is analyzed by complementary techniques: freeze-fracture electron microscopy, cryoelectron microscopy, and x-ray diffraction. In Mg(2+)-NCP aggregates, NCPs tend to stack on top of one another to form columns that are not long-range organized. In the presence of Spd(3+), NCPs precipitate to form a dense isotropic phase, a disordered phase of columns, a two-dimensional columnar hexagonal phase, or a three-dimensional crystal. The more ordered phases (two-dimensional or three-dimensional hexagonal) are found close to the precipitation line, where the number of positive charges carried by cations is slightly larger than the number of available negative charges of the NCPs. All ordered phases coexist with the dense isotropic phases. Formation of hexagonal and columnar phases is prevented by an excess of polycations.

  13. Magnetic phase diagram of the heavy fermion superconductor PrOs sub 4 Sb sub 1 sub 2

    CERN Document Server

    Tayama, T; Sugawara, H; Aoki, Y; Sato, H


    We investigated the magnetic phase diagram of the first Pr-based heavy fermion superconductor PrOs sub 4 Sb sub 1 sub 2 by means of high-resolution dc magnetization measurements in low temperatures down to 0.06 K. The temperature dependence of the magnetization M(T) at 0.1 kOe exhibits two distinct anomalies at T sub c sub 1 =1.83 K and T sub c sub 2 =1.65 K, in agreement with the specific heat measurements at zero field. Increasing magnetic field H, both T sub c sub 1 (H) and T sub c sub 2 (H) move toward lower temperatures without showing a tendency of intersecting to each other. Above 10 kOe, the transition at T sub c sub 2 (H) appears to merge into a line of the peak effect which is observed near the upper critical field H sub c sub 2 in the isothermal M(H) curves, suggesting a common origin for these two phenomena. The presence of the field-induced ordered phase (called phase A here) is confirmed for three principal directions above 40 kOe, with the anisotropic A-phase transition temperature T sub A :T s...

  14. Quantum vortex melting and phase diagram in the layered organic superconductor κ -(BEDT-TTF)2Cu(NCS ) 2 (United States)

    Uji, S.; Fujii, Y.; Sugiura, S.; Terashima, T.; Isono, T.; Yamada, J.


    Resistance and magnetic torque measurements have been performed to investigate vortex phases for a layered organic superconductor κ -(BEDT-TTF) 2Cu (NCS) 2 [BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene], which is modeled as stacks of Josephson junctions. At 25 mK, the out-of-plane resistivity increases at 0.6 T, has a step feature up to 4 T, and then increases again, whereas the in-plane resistivity monotonically increases above 4 T. The results show that both pancake vortices (PVs) and Josephson vortices (JVs) are in solid phases for μ0H 4 T, both PVs and JVs are in liquid phases. These melting transitions are predominantly induced by quantum fluctuations (not by thermal fluctuations). In the magnetic torque curves, the irreversibility transition is clearly observed, roughly corresponding to the melting transition of the PVs but no anomaly is found at the JV melting transition. The detailed vortex phase diagram is determined in a wide temperature region.

  15. Phase diagram of Janus particles: The missing dimension of pressure anisotropy (United States)

    Rezvantalab, Hossein; Beltran-Villegas, Daniel J.; Larson, Ronald G.


    Brownian dynamics simulations of single-patch Janus particles under sedimentation equilibrium reveal that the phases found at fixed temperature and volume fraction are extremely sensitive to small changes in lateral box dimension. We trace this sensitivity to an uncontrolled parameter, namely, the pressure component parallel to the hexagonally ordered layers formed through sedimentation. We employ a flexible-cell constant-pressure scheme to achieve explicit control over this usually overlooked parameter, enabling the estimation of phase behavior under given pressure anisotropy. Our results show an increase in the stability range of an orientationally ordered lamellar phase with lateral layer compression and suggest a novel mechanism to control solid-solid phase transitions with negligible change in system volume, thus showing prospect for design of novel structures and switchable crystals from anisotropic building blocks.

  16. Phase diagrams of lipid mixtures relevant to the study of membrane rafts

    DEFF Research Database (Denmark)

    Goni, Felix; Alonso, Alicia; Bagatolli, Luis


    The present paper reviews the phase properties of phosphatidylcholine-sphingomyelin-cholesterol mixtures, that are often used as models for membrane "raft" microdomains. The available data based on X-ray, microscopic and spectroscopic observations, surface pressure and calorimetric measurements, ...

  17. Experimentally Determined Phase Diagram for the Barium Sulfide-Copper(I) Sulfide System Above 873 K (600 °C) (United States)

    Stinn, Caspar; Nose, Katsuhiro; Okabe, Toru; Allanore, Antoine


    The phase diagram of the barium sulfide-copper(I) sulfide system was investigated above 873 K (600 °C) using a custom-built differential thermal analysis (DTA) apparatus. The melting point of barium sulfide was determined utilizing a floating zone furnace. Four new compounds, Ba2Cu14S9, Ba2Cu2S3, Ba5Cu4S7, and Ba9Cu2S10, were identified through quench experiments analyzed with wavelength dispersive X-ray spectroscopy (WDS) and energy dispersive X-ray analysis (EDS). A miscibility gap was observed between 72 and 92 mol pct BaS using both DTA experiments and in situ melts observation in a floating zone furnace. A monotectic was observed at 94.5 mol pct BaS and 1288 K (1015 °C).

  18. Phase Diagram of Hydrogen and a Hydrogen-Helium Mixture at Planetary Conditions by Quantum Monte Carlo Simulations. (United States)

    Mazzola, Guglielmo; Helled, Ravit; Sorella, Sandro


    Understanding planetary interiors is directly linked to our ability of simulating exotic quantum mechanical systems such as hydrogen (H) and hydrogen-helium (H-He) mixtures at high pressures and temperatures. Equation of state (EOS) tables based on density functional theory are commonly used by planetary scientists, although this method allows only for a qualitative description of the phase diagram. Here we report quantum Monte Carlo (QMC) molecular dynamics simulations of pure H and H-He mixture. We calculate the first QMC EOS at 6000 K for a H-He mixture of a protosolar composition, and show the crucial influence of He on the H metallization pressure. Our results can be used to calibrate other EOS calculations and are very timely given the accurate determination of Jupiter's gravitational field from the NASA Juno mission and the effort to determine its structure.

  19. Research Update: Magnetic phase diagram of EuTi1−xBxO3 (B = Zr, Nb

    Directory of Open Access Journals (Sweden)

    Ling Li


    Full Text Available We report the magnetic phase diagram of EuTi1−xBxO3 (B = Zr, Nb, determined from magnetization and heat capacity measurements. Upon Zr-doping, the antiferromagnetic ordering temperature TN of EuTi1−xZrxO3 gradually decreases from 5.6 K (x = 0 to 4.1 K (x = 1. Whereas a similar decrease in TN is observed for small amounts of Nb doping (x ≤ 0.05, ferromagnetism is induced in EuTi1−xNbxO3 with x > 0.05. The ferromagnetic interaction between localized Eu 4f spins mediated by itinerant electrons introduced by Nb doping results in the ferromagnetism in EuTi1−xNbxO3.

  20. Phase diagram and complex patterns in the modeling of the bromate-oxalic acid-Ce-acetone oscillating reaction

    Directory of Open Access Journals (Sweden)

    Janaina A. M. Pereira


    Full Text Available Simulations have been carried out on the bromate - oxalic acid - Ce(IV - acetone oscillating reaction, under flow conditions, using Field and Boyd's model (J. Phys. Chem. 1985, 89, 3707. Many different complex dynamic behaviors were found, including simple periodic oscillations, complex periodic oscillations, quasiperiodicity and chaos. Some of these complex oscillations can be understood as belonging to a Farey sequence. The many different behaviors were systematized in a phase diagram which shows that some regions of complex patterns were nested with one inside the other. The existence of almost all known dynamic behavior for this system allows the suggestion that it can be used as a model for some very complex phenomena that occur in biological systems.

  1. Pressure and temperature phase diagram of Gd{sub 2}Ti{sub 2}O{sub 7} under irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Catillon, G. [Université Paris-Est, G2I, EA4119, 5 Blvd. Descartes, F-77454 Marne la Vallée Cedex 2 (France); Chartier, A., E-mail: [CEA, DEN, DMN, SCCME, F-91191 Gif-Sur-Yvette Cedex (France)


    The pressure and temperature phase diagram of Gd{sub 2}Ti{sub 2}O{sub 7} under irradiation are calculated by means of molecular dynamics calculations. The critical temperature for amorphization obeys a linear law with pressure. Gd{sub 2}Ti{sub 2}O{sub 7} under irradiation transits towards the fluorite above this temperature and amorphizes below. The configuration of the Ti interstitial reveals to be the key of the amorphizability of Gd{sub 2}Ti{sub 2}O{sub 7}. Its stability depends upon disorder and pressure. Low pressure promotes the stabilization of Ti linked-polyhedra that drive the system to the amorphous state under irradiation. Conversely, high pressure activates its destabilization to interstitials that recombine with vacancies, driving the system to the fluorite structure under irradiation.

  2. Phase diagram of two-color QCD in a Dyson-Schwinger approach

    Energy Technology Data Exchange (ETDEWEB)

    Buescher, Pascal Joachim


    We investigate two-color QCD with N{sub f}=2 at finite temperatures and chemical potentials using a Dyson-Schwinger approach. We employ two different truncations for the quark loop in the gluon DSE: one based on the Hard-Dense/Hard-Thermal Loop (HDTL) approximation of the quark loop and one based on the back-coupling of the full, self-consistent quark propagator (SCQL). We compare results for the different truncations with each other as well as with other approaches. As expected, we find a phase dominated by the condensation of quark-quark pairs. This diquark condensation phase overshadows the critical end point and first-order phase transition which one finds if diquark condensation is neglected. The phase transition from the phase without diquark condensation to the diquark-condensation phase is of second order. We observe that the dressing with massless quarks in the HDTL approximation leads to a significant violation of the Silver Blaze property and to a too small diquark condensate. The SCQL truncation, on the other hand, is found to reproduce all expected features of the μ-dependent quark condensates. Moreover, with parameters adapted to the situation in other approaches, we also find good to very good agreement with model and lattice calculations in all quark quantities. We find indictions that the physics in recent lattice calculations is likely to be driven solely by the explicit chiral symmetry breaking. Discrepancies w.r.t. the lattice are, however, observed in two quantities that are very sensitive to the screening of the gluon propagator, the dressed gluon propagator itself and the phase-transition line at high temperatures.

  3. 700 °C isothermal section of Al–Cr–Si ternary phase diagram

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Zhe [School of Mechanical Engineering, Xiangtan University, Hunan 411105 (China); Key Laboratory of Materials Design and Preparation Technology of Hunan Province, Xiangtan University, Hunan 411105 (China); Li, Zhi, E-mail: [School of Mechanical Engineering, Xiangtan University, Hunan 411105 (China); Key Laboratory of Materials Design and Preparation Technology of Hunan Province, Xiangtan University, Hunan 411105 (China); Wang, Xinming; Liu, Yongxiong; Wu, Yu; Zhao, Manxiu; Yin, Fucheng [School of Mechanical Engineering, Xiangtan University, Hunan 411105 (China); Key Laboratory of Materials Design and Preparation Technology of Hunan Province, Xiangtan University, Hunan 411105 (China)


    Highlights: • Fourteen three-phase regions (one could be indirectly deduced) and τ{sub 1}, τ{sub 2} and τ{sub 3} have been determined experimentally in Al–Cr–Si isothermal section at 700 °C. • The Al{sub 11}Cr{sub 2} phase does not exist at 700 °C and τ{sub 3} is not an extension phase of Al{sub 11}Cr{sub 4} in the Al–Cr–Si system. • The solubility of Si in AlCr{sub 2} is relatively low in the Al–Cr–Si system, but the CrSi{sub 2} phase possesses a relatively high solubility of Al. The maximum Al solubility in CrSi{sub 2}, CrSi and Cr{sub 5}Si{sub 3} at 700 °C reaches 25.9, 3.5 and 9.0 at.%, respectively. - Abstract: The isothermal section of Al–Cr–Si system at 700 °C was determined by means of scanning electron microscopy coupled with energy dispersive X-ray spectroscopy and X-ray powder diffraction. In the 700 °C isothermal section, fourteen three-phase regions exist, three ternary compound named τ{sub 1}, τ{sub 2} and τ{sub 3} are confirmed to be stable and the Al{sub 11}Cr{sub 2} phase is not observed in this section. The solubility of Si in AlCr{sub 2} is relatively low in the Al–Cr–Si system, but the CrSi{sub 2} phase possesses a relatively high solubility of Al. The maximum Al solubility in CrSi{sub 2}, CrSi and Cr{sub 5}Si{sub 3} at 700 °C reaches 25.9, 3.5 and 9.0 at.%, respectively.

  4. Phase diagram and breathing dynamics of a single red blood cell and a biconcave capsule in dilute shear flow (United States)

    Yazdani, Alireza Z. K.; Bagchi, Prosenjit


    We present phase diagrams of the single red blood cell and biconcave capsule dynamics in dilute suspension using three-dimensional numerical simulations. The computational geometry replicates an in vitro linear shear flow apparatus. Our model includes all essential properties of the cell membrane, namely, the resistance against shear deformation, area dilatation, and bending, as well as the viscosity difference between the cell interior and suspending fluids. By considering a wide range of shear rate and interior-to-exterior fluid viscosity ratio, it is shown that the cell dynamics is often more complex than the well-known tank-treading, tumbling, and swinging motion and is characterized by an extreme variation of the cell shape. As a result, it is often difficult to clearly establish whether the cell is swinging or tumbling. Identifying such complex shape dynamics, termed here as “breathing” dynamics, is the focus of this article. During the breathing motion at moderate bending rigidity, the cell either completely aligns with the flow direction and the membrane folds inward, forming two cusps, or it undergoes large swinging motion while deep, craterlike dimples periodically emerge and disappear. At lower bending rigidity, the breathing motion occurs over a wider range of shear rates, and is often characterized by the emergence of a quad-concave shape. The effect of the breathing dynamics on the tank-treading-to-tumbling transition is illustrated by detailed phase diagrams which appear to be more complex and richer than those of vesicles. In a remarkable departure from the vesicle dynamics, and from the classical theory of nondeformable cells, we find that there exists a critical viscosity ratio below which the transition is independent of the viscosity ratio, and dependent on shear rate only. Further, unlike the reduced-order models, the present simulations do not predict any intermittent dynamics of the red blood cells.

  5. Effect of lipid composition on the structure and theoretical phase diagrams of DC-Chol/DOPE-DNA lipoplexes. (United States)

    Muñoz-Ubeda, Mónica; Rodríguez-Pulido, Alberto; Nogales, Aurora; Martín-Molina, Alberto; Aicart, Emilio; Junquera, Elena


    Lipoplexes constituted by calf-thymus DNA (CT-DNA) and mixed cationic liposomes consisting of varying proportions of the cationic lipid 3β-[N-(N',N'-dimethylaminoethane)-carbamoyl]cholesterol hydrochloride (DC-Chol) and the zwitterionic lipid, 1,2-dioleoyl-sn-glycero-3-phosphoetanolamine (DOPE) have been analyzed by means of electrophoretic mobility, SAXS, and fluorescence anisotropy experiments, as well as by theoretically calculated phase diagrams. Both experimental and theoretical studies have been run at several liposome and lipoplex compositions, defined in terms of cationic lipid molar fraction, α, and either the mass or charge ratios of the lipoplex, respectively. The experimental electrochemical results indicate that DC-Chol/DOPE liposomes, with a mean hydrodynamic diameter of around (120 ± 10) nm, compact and condense DNA fragments at their cationic surfaces by means of a strong entropically driven electrostatic interaction. Furthermore, the positive charges of cationic liposomes are compensated by the negative charges of DNA phosphate groups at the isoneutrality L/D ratio, (L/D)(ϕ), which decreases with the cationic lipid content of the mixed liposome, for a given DNA concentration. This inversion of sign process has been also studied by means of the phase diagrams calculated with the theoretical model, which confirms all the experimental results. SAXS diffractograms, run at several lipoplex compositions, reveal that, irrespectively of the lipoplex charge ratio, DC-Chol/DOPE-DNA lipoplexes show a lamellar structure, L(α), when the cationic lipid content on the mixed liposomes α ≥ 0.4, while for a lower content (α = 0.2) the lipoplexes show an inverted hexagonal structure, H(II), usually related with improved cell transfection efficiency. A similar conclusion is reached from fluorescence anisotropy results, which indicate that the fluidity on liposome and lipoplexes membrane, also related with better transfection results, increases as long as the

  6. Comprehensive phase diagram of two-dimensional space charge doped Bi2Sr2CaCu2O8+x. (United States)

    Sterpetti, Edoardo; Biscaras, Johan; Erb, Andreas; Shukla, Abhay


    The 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, a field-effect transistor geometry with an electrostatically doped, ultra-thin sample can be used. However, to probe the phase diagram, carrier density modulation beyond 1014 cm-2 and transport measurements performed over a large temperature range are needed. Here we use the space charge doping method 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 as a function of doping, temperature and disorder.

  7. Phase diagram of a lattice of vortex molecules in multicomponent superconductors and multilayer cuprate superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Y; Shivagan, D D; Iyo, A; Shirage, P M [National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8568 (Japan); Crisan, A [National Institute of Materials Physics, Bucharest 077125 (Romania); Tokiwa, K; Watanabe, T [Department of Applied Electronics, Tokyo University of Science, Noda 278-851 (Japan); Terada, N [Department of Nano-Structures and Advanced Materials, Graduate School of Science and Engineering, Kagoshima University, Korimoto, Kagoshima 890-0065 (Japan)], E-mail:


    The Abrikosov lattice in the multilayer cuprate superconductor CuBa{sub 2}Ca{sub 3}Cu{sub 3}O{sub y} (Cu-1223) has been experimentally and theoretically demonstrated to be composed of vortex molecules. Cu-1223 is considered to be a typical multicomponent superconductor. We show that in such a system the rotational freedom around the axis of the vortex molecular tube generates orientational disorder and the orientational glass (or crystal) phase, which is never present in conventional vortex lattices consisting of axisymmetric vortices. The emergence of the orientational glass phase and orientational order phase with orthorhombic distortion is a general property of vortex molecule lattices of the multiband type of multicomponent superconductors.

  8. HP-67 calculator programs for thermodynamic data and phase diagram calculations

    Energy Technology Data Exchange (ETDEWEB)

    Brewer, L.


    This report is a supplement to a tabulation of the thermodynamic and phase data for the 100 binary systems of Mo with the elements from H to Lr. The calculations of thermodynamic data and phase equilibria were carried out from 5000/sup 0/K to low temperatures. This report presents the methods of calculation used. The thermodynamics involved is rather straightforward and the reader is referred to any advanced thermodynamic text. The calculations were largely carried out using an HP-65 programmable calculator. In this report, those programs are reformulated for use with the HP-67 calculator; great reduction in the number of programs required to carry out the calculation results.

  9. The effect of gauche molecular conformations on the phase diagram of a Langmuir monolayer

    NARCIS (Netherlands)

    Zangi, R; Rice, SA


    Experimental and simulation studies have shown that the gauche conformational degrees of freedom of long-chain amphiphile molecules assembled in a dense Langmuir monolayer play an important role in determining the structures of the several phases that the monolayer supports. Nevertheless, for

  10. Binary phase diagram of monolayers of simple 1,2-diol derivatives

    DEFF Research Database (Denmark)

    Wolf, C. De; Bringezu, F.; Brezesinski, G.


    direction. Extrapolation of a plot of 1/cos(t) versus lateral pressure yields transition pressures to a phase with upright oriented molecules. Both pure compounds and all mixtures investigated show a non-zero lattice distortion at zero tilt angle indicating a probable herringbone packing of the molecules...

  11. The magnetic and nematic phase diagram of Ba1-xSrxFe2-yNiyAs2 (United States)

    Gong, Dongliang; Li, Shiliang; SC8, National Lab for superconductivity, IOP, CAS Team

    The correlation between magnetic and nematic orders has been widely studied in iron-based superconductors. The magnetic and nematic phase transitions may be both first order as in SrFe2As2,o or both second order as in BaFe2-xNixAs2. Within spin-nematic scenario, it is possible for a system to establish the nematic phase as second order while keeping the magnetic transition first-ordered. Experimentally, it is rather hard to distinguish a second-order transition from a weakly first-order transition. Here we have systematically studied the nematic susceptibility and magnetic susceptibility in the iron-based superconductor Ba1-xSrxFe2-yNiyAs2 by elastoresistivity and magnetic susceptibility measurements, respectively. The evolutions of the nematic and magnetic transitions from first order to second order can be continuously tuned by the substitution of Sr by Ba. Our results give a phase diagram that is consistent with the spin-nematic theory. Chinese Academy of Sciences, Ministry of Science and Technology of China, e National Science Foundation of China, China Academy of Engineering Physics.

  12. Compression and phase diagram of lithium hydrides at elevated pressures and temperatures by first-principles calculations

    CERN Document Server

    Chen, Yang M; Wu, Qiang; Geng, Hua Y; Yan, Xiao Z; Wang, Yi X; Wang, Zi W


    High pressure and high temperature properties of AB (A = $^6$Li, $^7$Li; B = H, D, T) are investigated with first-principles method comprehensively. It is found that the H$^{-}$ sublattice features in the low-pressure electronic structure near the Fermi level of LiH are shifted to that dominated by the Li$^{+}$ sublattice in compression. The lattice dynamics is studied in quasi-harmonic approximation, from which the phonon contribution to the free energy and the isotopic effects are accurately modelled with the aid of a parameterized double-Debye model. The obtained equation of state (EOS) matches perfectly with available static experimental data. The calculated principal Hugoniot is also in accordance with that derived from shock wave experiments. Using the calculated principal Hugoniot and the previous theoretical melting curve, we predict a shock melting point at 56 GPa and 1923 K. In order to establish the phase diagram for LiH, the phase boundaries between the B1 and B2 solid phases are explored. The B1-...

  13. Studies on the phase diagram of boron employing a neural network potential

    Energy Technology Data Exchange (ETDEWEB)

    Morawietz, Tobias; Behler, Joerg [Lehrstuhl fuer Theoretische Chemie, Ruhr-Universitaet Bochum (Germany); Parrinello, Michele [Department of Chemistry and Applied Biosciences, ETH Zuerich (Switzerland)


    The crystalline phases of elemental boron have a structural complexity unique in the periodic table. The complex connection pattern of the icosahedral building blocks forms a formidable challenge for the construction of accurate but efficient potentials. We present a high-dimensional neural network potential for boron, which is based on first-principles calculations and can be systematically improved. The potential is several orders of magnitude faster to evaluate than the underlying density-functional theory calculations and allows to perform long molecular dynamics and metadynamics simulations of large system. By a stepwise refinement of the potential and an application of the potential in metadynamics simulations we show that starting from random atomic positions the structure of {alpha}-boron is predicted in agreement with experiment. Further, pressure-induced phase transitions of {alpha}-boron are discussed.

  14. Synthesis of polycrystalline methane hydrate, and its phase stability and mechanical properties at elevated pressure (United States)

    Stern, L.A.; Kirby, S.H.; Durham, W.B.


    Test specimens of methane hydrate were grown under static conditions by combining cold, pressurized CH4 gas with H2O ice grains, then warming the system to promote the reaction CH4 (g) + 6H2O (s???l) ??? CH4??6H2O. Hydrate formation evidently occurs at the nascent ice/liquid water interface, and complete reaction was achieved by warming the system above 271.5 K and up to 289 K, at 25-30 MPa, for approximately 8 hours. The resulting material is pure methane hydrate with controlled grain size and random texture. Fabrication conditions placed the H2O ice well above its melting temperature before reaction completed, yet samples and run records showed no evidence for bulk melting of the ice grains. Control experiments using Ne, a non-hydrate-forming gas, verified that under otherwise identical conditions, the pressure reduction and latent heat associated with ice melting is easily detectable in our fabrication apparatus. These results suggest that under hydrate-forming conditions, H2O ice can persist metastably at temperatures well above its melting point. Methane hydrate samples were then tested in constant-strain-rate deformation experiments at T= 140-200 K, Pc= 50-100 MPa, and ????= 10-4-10-6 s-1. Measurements in both the brittle and ductile fields showed that methane hydrate has measurably different strength than H2O ice, and work hardens to a higher degree compared to other ices as well as to most metals and ceramics at high homologous temperatures. This work hardening may be related to a changing stoichiometry under pressure during plastic deformation; x-ray analyses showed that methane hydrate undergoes a process of solid-state disproportionation or exsolution during deformation at conditions well within its conventional stability field.

  15. Study of QCD Phase Diagram with Non-Zero Chiral Chemical Potential

    CERN Document Server

    Braguta, V V; Kotov, A Yu; Petersson, B; Skinderev, S A


    In this paper we report on lattice simulations of SU(3)-QCD with non-zero chiral chemical potential. We focus on the influence of the chiral chemical potential on the confinement/deconfinement phase transition and the breaking/restoration of chiral symmetry. The simulation is carried out with dynamical Wilson fermions. We find that the critical temperature rises as the chiral chemical potential grows.

  16. Phase diagrams in blends of poly(3-hydroxybutyric acid with various aliphatic polyesters

    Directory of Open Access Journals (Sweden)


    Full Text Available Phase behavior with immiscibility, miscibility, crystalline morphology, and kinetic analysis in blends of poly(3-hydroxybutyric acid (PHB with aliphatic polyesters such as poly(butylene adipate (PBA, poly(ethylene adipate (PEA, poly(trimethylene adipate (PTA, or poly(ethylene succinate (PESu, respectively, were explored mainly using differential scanning calorimeter (DSC and polarized-light optical microscopy (POM. Immiscibility phase behavior with reversible upper-critical-solution-temperature (UCST is common in the PHB/polyester blends. The polyester/polyester blend of PHB/PTA is partially miscible with no UCST in melt and amorphous glassy states within a composition range of PTA less than 50 wt%. The miscible crystalline/crystalline blend exhibits ring-banded spherulites at Tc = 50~100°C, with inter-ring spacing dependent on Tc. All immiscible or partially miscible PHB/polyester blends, by contrast, exhibit disrupted ringbanded spherulites or discrete spherical phase domains upon cooling from UCST to crystallization. The blends of PHB with all other aliphatic polyesters, such as PESu, PEA, PBA, etc. are only partially miscible or immiscible with an upper critical solution temperature (UCST at 180~221°C depending on blend composition. UCST with reversibility was verified.

  17. Thermoanalytical studies of carbamazepine: hydration/dehydration, thermal decomposition, and solid phase transitions

    Directory of Open Access Journals (Sweden)

    Mônia Aparecida Lemos Pinto


    Full Text Available Carbamazepine (CBZ, a widely used anticonvulsant drug, can crystallize and exhibits four polymorphic forms and one dihydrate. Anhydrous CBZ can spontaneously absorb water and convert to the hydrate form whose different crystallinity leads to lower biological activity. The present study was concerned to the possibility of recovering the hydrated form by heating. The thermal behavior of spontaneously hydrated carbamazepine was investigated by TG/DTG-DTA and DSC in dynamic atmospheres of air and nitrogen, which revealed that the spontaneous hydration of this pharmaceutical resulted in a Form III hydrate with 1.5 water molecules. After dehydration, this anhydrous Form III converted to Form I, which melted and decomposed in a single event, releasing isocyanic acid, as shown by evolved gas analysis using TG-FTIR. Differential scanning calorimetry analyses revealed that Form III melted and crystallized as Form I, and that subsequent cooling cycles only generated Form I by crystallization. Solid state decomposition kinetic studies showed that there was no change in the substance after the elimination of water by heating to 120 °C. Activation energies of 98 ± 2 and 93 ± 2 kJ mol-1 were found for the hydrated and dried samples, respectively, and similar profiles of activation energy as a function of conversion factor were observed for these samples.

  18. Elastic properties and stress-temperature phase diagrams of high-temperature phases with low-temperature lattice instabilities (United States)

    Thomas, John C.; Van der Ven, Anton


    The crystal structures of many technologically important high-temperature phases are predicted to have lattice instabilities at low temperature, making their thermodynamic and mechanical properties inaccessible to standard first principles approaches that rely on the (quasi) harmonic approximation. Here, we use the recently developed anharmonic potential cluster expansion within Monte Carlo simulations to predict the effect of temperature and anisotropic stress on the elastic properties of ZrH2, a material that undergoes diffusionless transitions among cubic, tetragonal, and orthorhombic phases. Our analysis shows that the mechanical properties of high-temperature phases with low-temperature vibrational instabilities are very sensitive to temperature and stress state. These findings have important implications for materials characterization and multi-scale simulations and suggest opportunities for enhanced strain engineering of high-temperature phases exhibiting soft-mode instabilities.

  19. Universal Off-Equilibrium Scaling of Critical Cumulants in the QCD Phase Diagram. (United States)

    Mukherjee, Swagato; Venugopalan, Raju; Yin, Yi


    Exploiting the universality between the QCD critical point and the three-dimensional Ising model, closed form expressions derived for nonequilibrium critical cumulants on the crossover side of the critical point reveal that they can differ in both magnitude and sign from equilibrium expectations. We demonstrate here that key elements of the Kibble-Zurek framework of nonequilibrium phase transitions can be employed to describe the dynamics of these critical cumulants. Our results suggest that observables sensitive to critical dynamics in heavy-ion collisions should be expressible as universal scaling functions, thereby providing powerful model-independent guidance in searches for the QCD critical point.

  20. Experimental phase diagram of zero-bias conductance peaks in superconductor/semiconductor nanowire devices. (United States)

    Chen, Jun; Yu, Peng; Stenger, John; Hocevar, Moïra; Car, Diana; Plissard, Sébastien R; Bakkers, Erik P A M; Stanescu, Tudor D; Frolov, Sergey M


    Topological superconductivity is an exotic state of matter characterized by spinless p-wave Cooper pairing of electrons and by Majorana zero modes at the edges. The first signature of topological superconductivity is a robust zero-bias peak in tunneling conductance. We perform tunneling experiments on semiconductor nanowires (InSb) coupled to superconductors (NbTiN) and establish the zero-bias peak phase in the space of gate voltage and external magnetic field. Our findings are consistent with calculations for a finite-length topological nanowire and provide means for Majorana manipulation as required for braiding and topological quantum bits.

  1. Conductivity, Thermal Measurements, and Phase Diagram of the Na2S2O7-NaHSO4 System

    DEFF Research Database (Denmark)

    Hatem, G.; Gaune-Escard, M.; Rasmussen, Søren Birk


    The conductivity of the Na2S2O7-NaHSO4 binary system has been measured for 15 different compositions in the full composition range, and in the temperature range 400-700 K.Phase transition temperatures were obtained, and the phase diagram constructed. It is of thesimple eutectic type, where......, as found earlier for theK2S2O7-KHSO4 system. For each composition measured of the Na2S2O7-NaHSO4 system inthe molten state, the conductivity has been expressed by equations of the form = A(X) +B(X)(T - Tm) + C(X)(T-Tm)^2, where Tm is the intermediate temperature of the measuredtemperature range....... the eutectic is found to have the composition X(CsHSO4) = 0.97, ascalculated from the measured thermodynamic properties, and to melt at 179°C. The partialenthalpy and entropy of mixing have been obtained, and the negative entropy points to astructural order of the melt, presumably due to hydrogen bonding...

  2. Phase diagram of dirty two-band superconductors and observability of impurity-induced s +i s state (United States)

    Silaev, Mihail; Garaud, Julien; Babaev, Egor


    We investigate the phase diagram of dirty two-band superconductors. This paper primarily focuses on the properties and observability of the time-reversal symmetry-breaking s +i s superconducting states, which can be generated in two-band superconductors by interband impurity scattering. We show that such states can appear in two distinct ways. First, according to a previously discussed scenario, the s +i s state can form as an intermediate phase at the impurity-driven crossover between s± and s++ states. We show that there is a second scenario where domains of the s +i s state exists in the form of an isolated dome inside the s± domain, completely detached from the transition between s± and s++ states. We demonstrate that in both cases the s +i s state generated by impurity scattering exists in an extremely small interval of impurity concentrations. Although this likely precludes direct experimental observation of the s +i s state formation due to this mechanism, this physics leads to the appearance of a region inside both the s± and s++ domains with unusual properties due to softening of normal modes.

  3. TES buffer-induced phase separation of aqueous solutions of several water-miscible organic solvents at 298.15 K: Phase diagrams and molecular dynamic simulations (United States)

    Taha, Mohamed; Lee, Ming-Jer


    Water and the organic solvents tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, 1-propanol, 2-propanol, tert-butanol, acetonitrile, or acetone are completely miscible in all proportions at room temperature. Here, we present new buffering-out phase separation systems that the above mentioned organic aqueous solutions can be induced to form two liquid phases in the presence of a biological buffer 2-[[1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl]amino]ethanesulfonic acid (TES). The lower liquid phase is rich in water and buffer, and the upper phase is organic rich. This observation has both practical and mechanistic interests. The phase diagrams of these systems were constructed by experimental measurements at ambient conditions. Molecular dynamic (MD) simulations were performed for TES + water + THF system to understand the interactions between TES, water, and organic solvent at molecular level. Several composition-sets for this system, beyond and inside the liquid-liquid phase-splitting region, have been simulated. Interestingly, the MD simulation for compositions inside the phase separation region showed that THF molecules are forced out from the water network to start forming a new liquid phase. The hydrogen-bonds, hydrogen-bonds lifetimes, hydrogen-bond energies, radial distribution functions, coordination numbers, the electrostatic interactions, and the van der Waals interactions between the different pairs have been calculated. Additionally, MD simulations for TES + water + tert-butanol/acetonitrile/acetone phase separation systems were simulated. The results from MD simulations provide an explanation for the buffering-out phenomena observed in [TES + water + organic solvent] systems by a mechanism controlled by the competitive interactions of the buffer and the organic solvent with water. The molecular mechanism reported here is helpful for designing new benign separation materials.

  4. Phase diagram and universality of the Lennard-Jones gas-liquid system

    KAUST Repository

    Watanabe, Hiroshi


    The gas-liquid phase transition of the three-dimensional Lennard-Jones particles system is studied by molecular dynamics simulations. The gas and liquid densities in the coexisting state are determined with high accuracy. The critical point is determined by the block density analysis of the Binder parameter with the aid of the law of rectilinear diameter. From the critical behavior of the gas-liquid coexisting density, the critical exponent of the order parameter is estimated to be β = 0.3285(7). Surface tension is estimated from interface broadening behavior due to capillary waves. From the critical behavior of the surface tension, the critical exponent of the correlation length is estimated to be ν = 0.63(4). The obtained values of β and ν are consistent with those of the Ising universality class. © 2012 American Institute of Physics.

  5. Electron doped layered nickelates: Spanning the phase diagram of the cuprates

    Energy Technology Data Exchange (ETDEWEB)

    Botana, Antia S.; Pardo, Victor; Norman, Michael R.


    Pr4Ni3O8 is an overdoped analog of hole-doped layered cuprates. Here we show via ab initio calculations that Ce-doped Pr4Ni3O8 (Pr3CeNi3O8) has the same electronic structure as the antiferromagnetic insulating phase of parent cuprates.We find that substantial Ce doping should be thermodynamically stable and that other 4+ cations would yield a similar antiferromagnetic insulating state, arguing this configuration is robust for layered nickelates of low-enough valence. The analogies with cuprates at different d fillings suggest that intermediate Ce-doping concentrations near 1/8 should be an appropriate place to search for superconductivity in these low-valence Ni oxides.

  6. Phase diagram of the two-dimensional O(3) model from dual lattice simulations

    CERN Document Server

    Bruckmann, Falk; Kloiber, Thomas; Sulejmanpasic, Tin


    We have simulated the asymptotically free two-dimensional O(3) model at nonzero chemical potential using the model's dual representation. We first demonstrate how the latter solves the sign (complex action) problem. The system displays a crossover at nonzero temperature, while at zero temperature it undergoes a quantum phase transition when mu reaches the particle mass (generated dynamically similar to QCD). The density follows a square root behavior universal for repulsive bosons in one spatial dimension. We have also measured the spin stiffness, known to be sensitive to the spatial correlation length, using different scaling trajectories to zero temperature and infinite size. It points to a dynamical critical exponent z=2. Comparisons to thermodynamic Bethe ansaetze are shown as well.

  7. Phase diagram of the restricted primitive model: charge-ordering instability

    Directory of Open Access Journals (Sweden)



    Full Text Available We study the phase behaviour of the restricted primitive model (RPM using a microscopic approach based on the method of collective variables with a reference system. Starting from the Hamiltonian of the RPM we derive the functional of the grand partition function given in terms of the two collective variables: the collective variables ρk and ck describing fluctuations of the total number density and charge density, respectively. Within the framework of the Gaussian approximation we found the boundary of stability with respect to fluctuations of the charge density. It is shown that due to the approximated character of the theory the boundary of stability is very sensitive to the particular choice of the long-range part of potential inside the hard core. This point is discussed in more detail.

  8. Entanglement and quantum phase diagrams of symmetric multi-qubit systems (United States)

    Calixto, Manuel; Castaños, Octavio; Romera, Elvira


    For general symmetric multi-qubit systems, the behavior of one- and two-qubit entanglement for Dicke, spin coherent and parity-adapted (even and odd) spin coherent states is determined. These quantum correlations are quantified by linear and von Neumann entropies of the corresponding one- and two-qubit reduced density matrices of the multi-qubit system. These states play a fundamental role in the study of Hamiltonian systems written in terms of collective generators of the angular momentum algebra like, for example, the Lipkin-Meshkov-Glick (LMG) model. Here we shall use these entanglement measures as a signature to characterize the different quantum phases that appear in these models.

  9. Hadron formation in relativistic nuclear collisions and the QCD phase diagram. (United States)

    Becattini, Francesco; Bleicher, Marcus; Kollegger, Thorsten; Schuster, Tim; Steinheimer, Jan; Stock, Reinhard


    We study particle production in ultrarelativistic nuclear collisions at CERN SPS and LHC energies and the conditions of chemical freeze-out. We determine the effect of the inelastic reactions between hadrons occurring after hadronization and before chemical freeze-out employing the ultrarelativistic quantum molecular dynamics hybrid model. The differences between the initial and the final hadronic multiplicities after the rescattering stage resemble the pattern of data deviation from the statistical equilibrium calculations. By taking these differences into account in the statistical model analysis of the data, we are able to reconstruct the original hadrochemical equilibrium points in the (T, μ(B)) plane which significantly differ from chemical freeze-out ones and closely follow the parton-hadron phase boundary recently predicted by lattice quantum chromodynamics.

  10. Communication: Charge transfer dominates over proton transfer in the reaction of nitric acid with gas-phase hydrated electrons (United States)

    Lengyel, Jozef; Med, Jakub; Slavíček, Petr; Beyer, Martin K.


    The reaction of HNO3 with hydrated electrons (H2O)n- (n = 35-65) in the gas phase was studied using Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry and ab initio molecular dynamics simulations. Kinetic analysis of the experimental data shows that OH-(H2O)m is formed primarily via a reaction of the hydrated electron with HNO3 inside the cluster, while proton transfer is not observed and NO3-(H2O)m is just a secondary product. The reaction enthalpy was determined using nanocalorimetry, revealing a quite exothermic charge transfer with -241 ± 69 kJ mol-1. Ab initio molecular dynamics simulations indicate that proton transfer is an allowed reaction pathway, but the overall thermochemistry favors charge transfer.

  11. The phase diagrams of KCaF3 and NaMgF3 by ab initio simulations (United States)

    Jakymiw, Clément; Vočadlo, Lidunka; Dobson, David P.; Bailey, Edward; Thomson, Andrew R.; Brodholt, John P.; Wood, Ian G.; Lindsay-Scott, Alex


    ABF3 compounds have been found to make valuable low-pressure analogues for high-pressure silicate phases that are present in the Earth's deep interior and that may also occur in the interiors of exoplanets. The phase diagrams of two of these materials, KCaF3 and NaMgF3, have been investigated in detail by static ab initio computer simulations based on density functional theory. Six ABF3 polymorphs were considered, as follows: the orthorhombic perovskite structure (GdFeO3-type; space group Pbnm); the orthorhombic CaIrO3 structure (Cmcm; commonly referred to as the "post-perovskite" structure); the orthorhombic Sb2S3 and La2S3 structures (both Pmcn); the hexagonal structure previously suggested in computer simulations of NaMgF3 (P63/mmc); the monoclinic structure found to be intermediate between the perovskite and CaIrO3 structures in CaRhO3 (P21/m). Volumetric and axial equations of state of all phases considered are presented. For KCaF3, as expected, the perovskite phase is shown to be the most thermodynamically stable at atmospheric pressure. With increasing pressure, the relative stability of the KCaF3 phases then follows the sequence: perovskite → La2S3 structure → Sb2S3 structure → P63/mmc structure; the CaIrO3 structure is never the most stable form. Above about 2.6 GPa, however, none of the KCaF3 polymorphs are stable with respect to dissociation into KF and CaF2. The possibility that high-pressure KCaF3 polymorphs might exist metastably at 300 K, or might be stabilised by chemical substitution so as to occur within the standard operating range of a multi-anvil press, is briefly discussed. For NaMgF3, the transitions to the high-pressure phases occur at pressures outside the normal range of a multi-anvil press. Two different sequences of transitions had previously been suggested from computer simulations. With increasing pressure, we find that the relative stability of the NaMgF3 phases follows the sequence: perovskite → CaIrO3 structure → Sb2S3

  12. Phase equilibria of carbon dioxide and methane gas-hydrates predicted with the modified analytical S-L-V equation of state

    Directory of Open Access Journals (Sweden)

    Span Roland


    Full Text Available Gas-hydrates (clathrates are non-stoichiometric crystallized solutions of gas molecules in the metastable water lattice. Two or more components are associated without ordinary chemical union but through complete enclosure of gas molecules in a framework of water molecules linked together by hydrogen bonds. The clathrates are important in the following applications: the pipeline blockage in natural gas industry, potential energy source in the form of natural hydrates present in ocean bottom, and the CO2 separation and storage. In this study, we have modified an analytical solid-liquid-vapor equation of state (EoS [A. Yokozeki, Fluid Phase Equil. 222–223 (2004] to improve its ability for modeling the phase equilibria of clathrates. The EoS can predict the formation conditions for CO2- and CH4-hydrates. It will be used as an initial estimate for a more complicated hydrate model based on the fundamental EoSs for fluid phases.

  13. The Establishment, Plotting and Statistic– Mathematical Interpretation of the Liquidus Surface from the Phase Equilibrium Diagram of the Ternary System Al-Cu-Si


    Florentina A. Cziple


    The paper forwards the conclusions of a survey performed on a mathematical model of the phase equilibrium from the ternary system Al-Cu-Si. The author presents the calculus of the statistic equation of the liquidus surface model from this diagram, the plotting and statistical-mathematical interpretation of the results obtained.

  14. The Establishment, Plotting and Statistic– Mathematical Interpretation of the Liquidus Surface from the Phase Equilibrium Diagram of the Ternary System Al-Cu-Si

    Directory of Open Access Journals (Sweden)

    Florentina A. Cziple


    Full Text Available The paper forwards the conclusions of a survey performed on a mathematical model of the phase equilibrium from the ternary system Al-Cu-Si. The author presents the calculus of the statistic equation of the liquidus surface model from this diagram, the plotting and statistical-mathematical interpretation of the results obtained.

  15. c-T phase diagram and Landau free energies of (AgAu)55 nanoalloy via neural-network molecular dynamic simulations (United States)

    Chiriki, Siva; Jindal, Shweta; Bulusu, Satya S.


    For understanding the structure, dynamics, and thermal stability of (AgAu)55 nanoalloys, knowledge of the composition-temperature (c-T) phase diagram is essential due to the explicit dependence of properties on composition and temperature. Experimentally, generating the phase diagrams is very challenging, and therefore theoretical insight is necessary. We use an artificial neural network potential for (AgAu)55 nanoalloys. Predicted global minimum structures for pure gold and gold rich compositions are lower in energy compared to previous reports by density functional theory. The present work based on c-T phase diagram, surface area, surface charge, probability of isomers, and Landau free energies supports the enhancement of catalytic property of Ag-Au nanoalloys by incorporation of Ag up to 24% by composition in Au nanoparticles as found experimentally. The phase diagram shows that there is a coexistence temperature range of 70 K for Ag28Au27 compared to all other compositions. We propose the power spectrum coefficients derived from spherical harmonics as an order parameter to calculate Landau free energies.

  16. Structural and electronic phase diagrams of CeFeAsO1-xFx and SmFeAsO1-xFx


    Maeter, Hemke; Borrero, Jorge Enrique Hamann; Goltz, Til; Spehling, Johannes; Kwadrin, Andrej; Kondrat, Agnieszka; Veyrat, Louis; Lang, Guillaume; Grafe, Hans-Joachim; Hess, Christian; Behr, Günter; Büchner, Bernd; Luetkens, Hubertus; Baines, Chris; Amato, Alex


    We have studied the structural and electronic phase diagrams of CeFeAsO1-xFx and SmFeAsO1-xFx by a detailed analysis of muon spin relaxation experiments, synchrotron X-ray diffraction, M\\"ossbauer spectroscopy, electrical resistivity, specific heat, and magnetic susceptibility measurements (Full abstract in the main document).

  17. Parametric diagram

    DEFF Research Database (Denmark)

    Hermund, Anders


    This paper will introduce the PhD research into applied 3d modeling and parametric design outlining the idea of a parametric diagram linked to philosophical and applied examples.......This paper will introduce the PhD research into applied 3d modeling and parametric design outlining the idea of a parametric diagram linked to philosophical and applied examples....

  18. Preparation and Evaluation of Tretinoin Microemulsion Based on Pseudo-Ternary Phase Diagram

    Directory of Open Access Journals (Sweden)

    Fatemeh Leis


    Full Text Available Purpose: The aim of the present research was to formulate a transparent microemolsion as a topical delivery system for tretinoin for the treatment of acne. Methods: Microemulsion formulations prepared by mixing appropriate amount of surfactant including Tween 80 and Labrasol, co-surfactant such as propylene glycol (PG and oil phase including isopropyl myristate – transcutol P (10:1 ratio. The prepared microemolsions were evaluated regarding their particle size, zeta potential, conductivity, stability, viscosity, differential scanning calorimetry (DSC, scanning electron microscopy (SEM, refractory index (RI and pH. Results: The results showed that maximum oil was incorporated in microemolsion system that was contained surfactant to co-surfactant ratio (Km of 4:1. The mean droplets size range of microemulsion formulation were in the range of 14.1 to 36.5 nm and its refractory index (RI and pH were 1.46 and 6.1, respectively. Viscosity range was 200-350 cps. Drug release profile showed 49% of the drug released in the first 8 hours of experiment belong to ME-7. Also, Hexagonal and cubic structures were seen in the SEM photograph of the microemulsions. Conclusion: physicochemical properties and in vitro release were dependent upon the contents of S/C, water and, oil percentage in formulations.Also, ME-7 may be preferable for topical tretinoin formulation.

  19. Critical point in the phase diagram of primordial quark-gluon matter from black hole physics (United States)

    Critelli, Renato; Noronha, Jorge; Noronha-Hostler, Jacquelyn; Portillo, Israel; Ratti, Claudia; Rougemont, Romulo


    Strongly interacting matter undergoes a crossover phase transition at high temperatures T ˜1012 K and zero net-baryon density. A fundamental question in the theory of strong interactions, QCD, is whether a hot and dense system of quarks and gluons displays critical phenomena when doped with more quarks than antiquarks, where net-baryon number fluctuations diverge. Recent lattice QCD work indicates that such a critical point can only occur in the baryon dense regime of the theory, which defies a description from first principles calculations. Here we use the holographic gauge/gravity correspondence to map the fluctuations of baryon charge in the dense quark-gluon liquid onto a numerically tractable gravitational problem involving the charge fluctuations of holographic black holes. This approach quantitatively reproduces ab initio results for the lowest order moments of the baryon fluctuations and makes predictions for the higher-order baryon susceptibilities and also for the location of the critical point, which is found to be within the reach of heavy-ion collision experiments.

  20. Variation in emulsion stabilization behavior of hybrid silicone polymers with change in molecular structure: Phase diagram study. (United States)

    Mehta, Somil C; Somasundaran, P; Kulkarni, Ravi


    Silicone oils are widely used in cosmetics and personal care applications to improve softness and condition skin and hair. Being insoluble in water and most hydrocarbons, a common mode of delivering them is in the form of emulsions. Currently most applications use polyoxyethylene (non-ionic) modified siloxanes as emulsifiers to stabilize silicone oil emulsions. However, ionically grafted silicone polymers have not received much attention. Ionic silicones have significantly different properties than the non-ionic counterpart. Thus considerable potential exists to formulate emulsions of silicones with different water/silicone oil ratios for novel applications. In order to understand the mechanisms underlying the effects of hydrophilic modifications on the ability of hybrid silicone polymers to stabilize various emulsions, this article focuses on the phase diagram studies for silicone emulsions. The emulsifying ability of functional silicones was seen to depend on a number of factors including hydrophilicity of the polymer, nature of the functional groups, the extent of modification, and the method of emulsification. It was observed that the region of stable emulsion in a phase diagram expanded with increase in shear rate. At a given shear rate, the region of stable emulsion and the nature of emulsion (water-in-oil or oil-in-water) was observed to depend on hydrophilic-hydrophobic balance of the hybrid silicone emulsifier. At a fixed amount of modification, the non-ionically modified silicone stabilized an oil-in-water emulsion, whereas the ionic silicones stabilized inverse water-in-oil emulsions. This was attributed to the greater hydrophilicity of the polyoxyethylene modified silicones than the ionic counterparts. In general, it is postulated that with progressive increase in hydrophilicity of hybrid silicone emulsifiers, their tendency to stabilize water-in-oil emulsion decreases with corresponding increase in oil-in-water emulsion. Further, this behavior is

  1. Electronic phase diagram of half-doped perovskite manganites on the plane of quenched disorder versus one-electron bandwidth (United States)

    Tomioka, Y.; Ito, T.; Sawa, A.


    For half-doped manganese oxides that have a perovskite structure, R E1 -xA ExMn O3 (x =0.5 ) (RE and AE are rare-earth and alkaline-earth elements, respectively), the phase competition (stability) between the antiferromagnetic charge- or orbital-ordered insulator (CO/OO AFI), ferromagnetic metal (FM), layered (A-type) antiferromagnetic phase [AF(A)], and spin-glass-like insulator (SGI), have been studied using single crystals prepared by the floating zone method. The CO/OO AFI, FM, AF(A), and SGI are displayed on the plane of the disorder (the variance of the RE and AE cations) versus the effective one-electron bandwidth (the averaged ionic radius of the RE and AE). In the plane of the disorder versus the effective one-electron bandwidth, similar to the phase diagram of R E1 -xA ExMn O3 (x =0.45 ), the CO/OO AFI, FM, and SGI dominate at the lower-left, right, and upper regions, respectively. However, the CO/OO AFI for x =0.5 is more stable than that for x =0.45 , and it expands to the plane points that correspond to the R E0.5S r0.5Mn O3 (R E =Nd and Sm) specimens as the hole concentration is commensurate with the ordering of M n3 + /M n4 + with a ratio of 1/1. The y -dependent electronic phases for R E0.5(Sr1-yB ay ) 0.5Mn O3 (0 ≤y ≤0.5 ) (R E =Sm , N d0.5S m0.5 , Nd, and Pr) show that the AF(A) intervenes between the CO/OO AFI and FM. Besides the region around (La1-yP ry ) 0.5S r0.5Mn O3 (0 ≤y ≤1 ) that has a smaller disorder, the AF(A) also exists at the regions around R E0.5(Sr1-yB ay ) 0.5Mn O3 (0 indicates that the AF(A) is rather robust against the increased disorder, even though an ordering of the (x2-y2 ) orbital occurs. This study has comprehensively investigated the effects of the disorder on the AF(A) as well as on the competition between the CO/OO AFI, FM, and AF(A) that is unique to x =0.5 . The comparison of phase diagrams between x =0.45 and 0.5 brings further insights into the understanding of the rich electronic phases of manganites.

  2. Neutron diffraction investigation of the H -T phase diagram above the longitudinal incommensurate phase of BaCo2V2O8 (United States)

    Grenier, B.; Simonet, V.; Canals, B.; Lejay, P.; Klanjšek, M.; Horvatić, M.; Berthier, C.


    The quasi-one-dimensional antiferromagnetic Ising-like compound BaCo2V2O8 has been shown to be describable by the Tomonaga-Luttinger liquid theory in its gapless phase induced by a magnetic field applied along the Ising axis. Above 3.9 T, this leads to an exotic field-induced low-temperature magnetic order, made of a longitudinal incommensurate spin-density wave, stabilized by weak interchain interactions. By single-crystal neutron diffraction we explore the destabilization of this phase at a higher magnetic field. We evidence a transition at around 8.5 T towards a more conventional magnetic structure with antiferromagnetic components in the plane perpendicular to the magnetic field. The phase diagram boundaries and the nature of this second field-induced phase are discussed with respect to previous results obtained by means of nuclear magnetic resonance and electron spin resonance, and in the framework of the simple model based on the Tomonaga-Luttinger liquid theory, which obviously has to be refined in this complex system.

  3. Calculation of solid-fluid phase equilibria and three-dimensional phase diagrams for binary systems of naphthalene and supercritical fluids

    Energy Technology Data Exchange (ETDEWEB)

    Nitta, Tomoshige; Katayama, Takashi (Osaka Univ. (Japan). Dept. of Chemical Engineering); Ikeda, Kazufumi


    Algorithms for calculating phase equilibria of solid-fluid and fluid-fluid systems are described, together with the characteristics of phase diagrams of binary mixtures of naphthalene and the supercritical fluids such as ethylene, carbon dioxide, fluoroform, and chlorotrifluoromethane, as calculated from the Soave-Redlich-Kwong equation of state. The sublimation enthalpy, the molar heat capacity difference between vapor and solid, and the molar volume of the solid are determined for naphthalene by the least-squares method from experimental data for the sublimation pressure and the melting curve. The binary parameters k[sub ij] and c[sub ij] for the Soave-Redlich-Kwong constants a and b are determined from the solubilities of solid naphthalene in the supercritical fluids. An algorithm for calculating the phase equilibrium based on phase stability analysis, in which the search region is contracted by using the bisection principle, is developed for use in determining the true, thermodynamically most stable solution from among the various combinations of gas, liquid, and solid.

  4. Investigations on the Phase Diagram and Interaction Parameter of Poly(styrene-b-1,3-cyclohexadiene) Copolymers

    KAUST Repository

    Misichronis, Konstantinos


    A series of linear diblock copolymers containing polystyrene (PS) and poly(1,3-cyclohexadiene) (PCHD) with high 1,4-microstructure (>87%) was synthesized by anionic polymerization and high vacuum techniques. Microphase separation in the bulk was examined by transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) and compared to computational analysis of the predicted morphological phase diagram for this system. Because of the high conformational asymmetry between PS and PCHD, these materials self-assemble into typical morphologies expected for linear diblock copolymer systems and atypical structures. Rheological measurements were conducted and revealed order–disorder transition temperatures (TODT), for the first time for PS-b-PCHD copolymers, resulting in a working expression for the effective interaction parameter χeff = 32/T – 0.016. Furthermore, we performed computational studies that coincide with the experimental results. These copolymers exhibit well-ordered structures even at high temperatures (∼260 °C) therefore providing a better insight concerning their microphase separation at the nanoscale which is important for their potential use in nanotechnology and/or nanolithography applications.

  5. Phase diagram of the correlated quarter-filled-band organic salt series (o-DMTTF)2X (X = Cl, Br, I) (United States)

    Foury-Leylekian, P.; Auban-Senzier, P.; Coulon, C.; Jeannin, O.; Fourmigué, M.; Pasquier, C.; Pouget, J.-P.


    The 2:1 family of organic salts (o-DMTTF)2X (X = Cl, Br, I) exhibits regular stacks and a high-symmetry structure, which provide a perfect three-quarter-filling-band system allowing a rich phase diagram in the presence of strong electronic correlations. In this paper, we present a detailed study of this series combining complementary experimental techniques such as resistivity, thermopower, electron spin resonance, static magnetic measurements, and x-ray diffraction. In particular, we show that at ambient pressure (o-DMTTF)2X with X = Br and Cl undergoes two successive phase transitions setting successively a 4kF charge density and bond order wave order, then a spin-Peierls (SP) ground state. We discuss the symmetry of these phases and its relationship with the transport and magnetic properties. These phases are also followed under pressure by transport experiments, allowing the establishment of a generic phase diagram for this series of salts, where, with the onset of a one-dimensional to three-dimensional deconfinement transition, the 4kF order vanishes and the SP ground state transforms into a Peierls one. Interestingly, this phase diagram differs significantly from the one previously reported in other three-quarter-filled systems such as (TMTTF)2X and δ-(EDT-TTF-CONMe2)2X.

  6. Electronic diagrams

    CERN Document Server

    Colwell, Morris A


    Electronic Diagrams is a ready reference and general guide to systems and circuit planning and in the preparation of diagrams for both newcomers and the more experienced. This book presents guidelines and logical procedures that the reader can follow and then be equipped to tackle large complex diagrams by recognition of characteristic 'building blocks' or 'black boxes'. The goal is to break down many of the barriers that often seem to deter students and laymen in learning the art of electronics, especially when they take up electronics as a spare time occupation. This text is comprised of nin

  7. Born-Oppenheimer molecular dynamics studies of Pb(ii) micro hydrated gas phase clusters (United States)

    León-Pimentel, C. I.; Amaro-Estrada, J. I.; Saint-Martin, H.; Ramírez-Solís, A.


    In this work, a theoretical investigation was made to assess the coordination properties of Pb(ii) in [Pb(H2O)n]2+ clusters, with n = 4, 6, 8, 12, and 29, as well as to study proton transfer events, by means of Born-Oppenheimer molecular dynamics simulations at the B3LYP/aug-cc-pVDZ-pp/6-311G level of theory, that were calibrated in comparison with B3LYP/aug-cc-pVDZ-PP/aug-cc-pVDZ calculations. Hemidirected configurations were found in all cases; the radial distribution functions (RDFs) produced well defined first hydration shells (FHSs) for n = 4,6,8, and 12, that resulted in a coordination number CN = 4, whereas a clear-cut FHS was not found for n = 29 because the RDF did not have a vacant region after the first maximum; however, three water molecules remained directly interacting with the Pb ion for the whole simulation, while six others stayed at average distances shorter than 4 Å but dynamically getting closer and farther, thus producing a CN ranging from 6 to 9, depending on the criterion used to define the first hydration shell. In agreement with experimental data and previous calculations, proton transfer events were observed for n ≤8 but not for n ≥12 . For an event to occur, a water molecule in the second hydration shell had to make a single hydrogen bond with a water molecule in the first hydration shell.

  8. Phase equilibrium modeling of gas hydrate systems for CO2 capture

    DEFF Research Database (Denmark)

    Herslund, Peter Jørgensen; Thomsen, Kaj; Abildskov, Jens


    Kihara cell potential. Model II uses a two-parameter explicit expression for the Langmuir adsorption coefficient, based on Langmuir adsorption theory. With two hydrate formers, four parameters in the Kihara cell potentials are fitted for Model I. Sixteen parameters are required to be fitted for Model II...

  9. Hydrate phase equilibria of CO2+N2+aqueous solution of THF, TBAB or TBAF system

    DEFF Research Database (Denmark)

    Sfaxi, Imen Ben Attouche; Durand, Isabelle; Lugo, Rafael


    We report hydrate dissociation conditions of CO2 (15 and 30mol%)+N2 (85 and 70mol%) in the presence of aqueous solutions of THF, TBAB or TBAF. The concentrations of TBAB and TBAF in the aqueous solutions are 5wt% and 9wt% while THF concentration in aqueous solution is 3mol%. Two different experim...

  10. Neutron scattering investigations of the properties of the x - T phase diagram of Rb sub 1 sub - sub x (NH sub 4) sub x I mixed crystals

    CERN Document Server

    Smirnov, L S; Savenko, B N


    The x - T phase diagram of Rb sub 1 sub - sub x (NH sub 4) sub x I is studied using samples with the ammonium concentration 0.01phase transition from alpha-phase to beta-phase is observed at ammonium concentrations x = 0.50 and x = 0.66. Inelastic incoherent neutron scattering detects a region of the orientional glass state at ammonium concentrations 0.29

  11. Two types of phase diagrams for two-species Bose-Einstein condensates and the combined effect of the parameters (United States)

    Li, Z. B.; Liu, Y. M.; Yao, D. X.; Bao, C. G.


    Under the Thomas-Fermi approximation, an approach is proposed to solve the coupled Gross-Pitaevskii equations (CGP) for the two-species Bose-Einstein condensate analytically. The essence of this approach is to find out the building blocks to build the solution. By introducing the weighted strengths, relatively simpler analytical solutions have been obtained. A number of formulae have been deduced to relate the parameters when the system is experimentally tuned at various status. These formulae demonstrate the combined effect of the parameters, and are useful for the evaluation of their magnitudes. The whole parameter space is divided into zones, where each supports a specific phase. All the boundaries separating these zones have analytical expressions. Based on the division, the phase diagrams against any set of parameters can be plotted. In addition, by introducing a model for the asymmetric states, the total energies of the lowest symmetric and asymmetric states have been compared. Thereby, in which case the former will be replaced by the latter has been evaluated. The CGP can be written in a matrix form. For repulsive inter-species interaction V AB , when the parameters vary and cross over the singular point of the matrix, a specific state transition will happen and the total energy of the lowest symmetric state will increase remarkably. This provides an excellent opportunity for the lowest asymmetric state to emerge as the ground state. For attractive V AB , when the parameters tend to a singular point, the system will tend to collapse. The effects caused by the singular points have been particularly studied.

  12. Applications of Phase Diagrams in Metallurgy and Ceramics: Proceedings of a Workshop Held at the National Bureau of Standards, Gaithersburg, Maryland, January 10-12, 1977. Volumes 1 [and] 2. (United States)

    Carter, G. C., Ed.

    This document is a special National Bureau of Standards publication on a Workshop on Applications of Phase Diagrams in Metallurgy and Ceramics. The purposes of the Workshop were: (1) to assess the current national and international status of phase diagram determinations and evaluations for alloys, ceramics and semiconductors; (2) to determine the…

  13. H-T phase diagram and the nature of vortex-glass phase in a quasi-two-dimensional superconductor: Sn-metal layer sandwiched between graphene sheets

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Masatsugu; Suzuki, Itsuko S.; Walter, Juergen


    The magnetic properties of a quasi-two-dimensional (2D) superconductor, Sn-metal graphite (MG), are studied using DC and AC magnetic susceptibility. Sn-MG has a unique layered structure where Sn metal layer is sandwiched between adjacent graphene sheets. This compound undergoes a superconducting transition at T{sub c}=3.75 K at H=0. The H-T diagram of Sn-MG is similar to that of a quasi-2D superconductors. The phase boundaries of vortex liquid, vortex glass, and vortex lattice phase merge into a multicritical point located at T*=3.4 K and H*=40 Oe. There are two irreversibility lines denoted by H{sub gl} (de Almeida-Thouless type) and H{sub gl{sup '}} (Gabay-Toulouse type), intersecting at T{sub 0}{sup '}=2.5 K and H{sub 0}{sup '}=160 Oe. The nature of slow dynamic and nonlinearity of the vortex glass phase is studied.

  14. The happy marriage between electron-phonon superconductivity and Mott physics in Cs3C60: A first-principle phase diagram (United States)

    Capone, Massimo; Nomura, Yusuke; Sakai, Shiro; Giovannetti, Gianluca; Arita, Ryotaro

    The phase diagram of doped fullerides like Cs3C60 as a function of the spacing between fullerene molecules is characterized by a first-order transition between a Mott insulator and an s-wave superconductor with a dome-shaped behavior of the critical temperature. By means of an ab-initio modeling of the bandstructure, the electron-phonon interaction and the interaction parameter and a Dynamical Mean-Field Theory solution, we reproduce the phase diagram and demonstrate that phonon superconductivity benefits from strong correlations confirming earlier model predictions. The role of correlations is manifest also in infrared measurements carried out by L. Baldassarre. The superconducting phase shares many similarities with ''exotic'' superconductors with electronic pairing, suggesting that the anomalies in the ''normal'' state, rather than the pairing glue, can be the real common element unifying a wide family of strongly correlated superconductors including cuprates and iron superconductors

  15. SCADA Diagram


    Rose, Matthew


    Matthew Rose worked at the Naval Postgraduate School as a graphic designer from February 2002-November 2011. His work for NPS included logos, brochures, business packs, movies/presentations, posters, the CyberSiege video game and many other projects. This material was organized and provided by the artist, for inclusion in the NPS Archive, Calhoun. Includes these files:; powerline.jpg; SCADA; SCADA diagram.pdf; SCADA diagramsmall.pdf; SCADA2.pdf

  16. Application of the electrical characterization to the study of the hydrated phases of the cement with coal bottom ash; Aplicacion de la caracterizacion electrica al estudio de las fases hidratadas de cemento con adicion de escorias de centrales termicas

    Energy Technology Data Exchange (ETDEWEB)

    Menendez, E.; Frutos, J. de; Alvaro, A. M.


    The present paper investigates the influence of using Bottom and Fly Ash as partial replacement of cement in the hydration process. Through measurements of electrical impedance spectroscopy (EIS) and X -ray diffraction (XRD), we analyze from the early stages to the hydration process to the end. Values of EIS, XRD and its relation, are used to determine transformation of hydrated phases, and for each of the substitutions, is indicated as modified the hydrated phase as a function of time and compared it with the reference material. It also proves the relevance of using EIS measures in real time, and as non destructive testing to characterize the hydration process of these materials. (Author)

  17. Effect of Ammonia on the Gas-Phase Hydration of the Common Atmospheric Ion HSO4-

    Directory of Open Access Journals (Sweden)

    Fangqun Yu


    Full Text Available Hydration directly affects the mobility, thermodynamic properties, lifetime and nucleation rates of atmospheric ions. In the present study, the role of ammonia on the formation of hydrogen bonded complexes of the common atmospheric hydrogensulfate (HSO4- ion with water has been investigated using the Density Functional Theory (DFT. Our findings rule out the stabilizing effect of ammonia on the formation of negatively charged cluster hydrates and show clearly that the conventional (classical treatment of ionic clusters as presumably more stable compared to neutrals may not be applicable to pre-nucleation clusters. These considerations lead us to conclude that not only quantitative but also qualitative assessment of the relative thermodynamic stability of atmospheric clusters requires a quantum-chemical treatment.

  18. Phase diagram of binary colloidal rod-sphere mixtures from a 3D real-space analysis of sedimentation-diffusion equilibria. (United States)

    Bakker, Henriëtte E; Dussi, Simone; Droste, Barbera L; Besseling, Thijs H; Kennedy, Chris L; Wiegant, Evert I; Liu, Bing; Imhof, Arnout; Dijkstra, Marjolein; van Blaaderen, Alfons


    Self-assembly of binary particle systems offers many new opportunities for materials science. Here, we studied sedimentation equilibria of silica rods and spheres, using quantitative 3D confocal microscopy. We determined not only pressure, density and order parameter profiles, but also the experimental phase diagram exhibiting a stable binary smectic liquid-crystalline phase (Sm2). Using computer simulations we confirmed that the Sm2-phase can be stabilized by entropy alone, which opens up the possibility of combining new materials properties at a wide array of length scales.

  19. Magnetic Properties and Phase Diagram of Ni50Mn_{50-x}Ga_{x/2}In_{x/2} Magnetic Shape Memory Alloys (United States)

    Xu, Xiao; Yoshida, Yasuki; Omori, Toshihiro; Kanomata, Takeshi; Kainuma, Ryosuke


    Ni50Mn50- x Ga x/2In x/2 magnetic shape memory alloys were systematically prepared, and the magnetic properties as well as the phase diagram, including atomic ordering, martensitic and magnetic transitions, were investigated. The B2- L21 order-disorder transformation showed a parabolic-like curve against the Ga+In composition. The martensitic transformation temperature was found to decrease with increasing Ga+In composition and to slightly bend downwards below the Curie temperature of the parent phase. Spontaneous magnetization was investigated for both parent and martensite alloys. The magnetism of martensite phase was found to show glassy magnetic behaviors by thermomagnetization and AC susceptibility measurements.

  20. Thermochemistry of the Reaction of SF6 with Gas-Phase Hydrated Electrons: A Benchmark for Nanocalorimetry. (United States)

    Akhgarnusch, Amou; Höckendorf, Robert F; Beyer, Martin K


    The reaction of sulfur hexafluoride with gas-phase hydrated electrons (H2O)n(-), n ≈ 60-130, is investigated at temperatures T = 140-300 K by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. SF6 reacts with a temperature-independent rate of 3.0 ± 1.0 × 10(-10) cm(3) s(-1) via exclusive formation of the hydrated F(-) anion and the SF5(•) radical, which evaporates from the cluster. Nanocalorimetry yields a reaction enthalpy of ΔHR,298K = 234 ± 24 kJ mol(-1). Combined with literature thermochemical data from bulk aqueous solution, these result in an F5S-F bond dissociation enthalpy of ΔH298K = 455 ± 24 kJ mol(-1), in excellent agreement with all high-level quantum chemical calculations in the literature. A combination with gas-phase literature thermochemistry also yields an experimental value for the electron affinity of SF5(•), EA(SF5(•)) = 4.27 ± 0.25 eV.

  1. The plutonium–oxygen phase diagram in the 25–900 °C range: Non-existence of the PuO{sub 1.515} phase

    Energy Technology Data Exchange (ETDEWEB)

    Haschke, John M.; Dinh, Long N., E-mail:; McLean, William


    Evaluation of data for phases formed in the Pu–O system at temperatures below 900 °C shows that the observed oxides are not at equilibrium. Results are consistent with coexistence of a hexagonal solid solution (hex-PuO{sub 1.5+z}, 0 ⩽ z ⩽ 0.010) and a cubic phase (cub-PuO{sub 1.60}) in equilibrium at 800 °C, but fail to confirm that the O/Pu ratio of the body-centered-cubic (bcc) oxide formed near the sesquioxide composition is 1.515 (1.52) or that bcc-PuO{sub 1.515} is formed by the peritectic reaction of hex-PuO{sub 1.510} with cub-PuO{sub 1.60}. Stable Pu(IV)/Pu(III) ratios observed for products of the Pu–H{sub 2}O reaction correspond to members of the Pu{sub n}O{sub 2n−2} homologous series, but a product is not formed at O/Pu = 1.515. Metastable bcc-PuO{sub 1.50} (n = 4) and stable hex-PuO{sub 1.5+z} coexist below 285 °C, the point at which reversible eutectic decomposition of cubic PuO{sub 1.60} (n = 5) produces a non-equilibrium mixture of bcc-PuO{sub 1.50} and sub-stoichiometric dioxide (PuO{sub 2−y}). Transformation of bcc-PuO{sub 1.50} to stable hex-PuO{sub 1.50} and reactions of the hexagonal oxide to form higher-composition cubic phases are kinetically hindered. An alternative diagram describing non-equilibrium chemical behavior of the Pu–O system is presented.

  2. Simulation of phase diagram and transformation structure evolution by the use of Monte Carlo method; Monte Carlo ho wo katsuyoshita heiko jotaizu to hentai soshiki keisei no simulation

    Energy Technology Data Exchange (ETDEWEB)

    Matsumiya, T. [Nippon Steel Corporation, Tokyo (Japan)


    The Monte Carlo method was used to simulate an equilibrium diagram, and structural formation of transformation and recrystallization. In simulating the Cu-A equilibrium diagram, the calculation was performed by laying 24 face centered cubic lattices including four lattice points in all of the three directions, and using a simulation cell consisting of lattice points of a total of 24{sup 3}{times}4 points. Although this method has a possibility to discover existence of an unknown phase as a result of the calculation, problems were found left in handling of lattice mitigation, and in simulation of phase diagrams over phases with different crystal structures. In simulation of the transformation and recrystallization, discussions were given on correspondence of 1MCS to time when the lattice point size is increased, and on handling of nucleus formation. As a result, it was estimated that in three-dimensional grain growth, the average grain size is proportional to 1/3 power of the MCS number, and the real time against 1MCS is proportional to three power of the lattice point size. 11 refs., 8 figs., 2 tabs.

  3. Carbon dioxide hydrate phase equilibrium and cage occupancy calculations using ab initio intermolecular potentials. (United States)

    Velaga, Srinath C; Anderson, Brian J


    Gas hydrate deposits are receiving increased attention as potential locations for CO2 sequestration, with CO2 replacing the methane that is recovered as an energy source. In this scenario, it is very important to correctly characterize the cage occupancies of CO2 to correctly assess the sequestration potential as well as the methane recoverability. In order to predict accurate cage occupancies, the guest–host interaction potential must be represented properly. Earlier, these potential parameters were obtained by fitting to experimental equilibrium data and these fitted parameters do not match with those obtained by second virial coefficient or gas viscosity data. Ab initio quantum mechanical calculations provide an independent means to directly obtain accurate intermolecular potentials. A potential energy surface (PES) between H2O and CO2 was computed at the MP2/aug-cc-pVTZ level and corrected for basis set superposition error (BSSE), an error caused due to the lower basis set, by using the half counterpoise method. Intermolecular potentials were obtained by fitting Exponential-6 and Lennard-Jones 6-12 models to the ab initio PES, correcting for many-body interactions. We denoted this model as the “VAS” model. Reference parameters for structure I carbon dioxide hydrate were calculated using the VAS model (site–site ab initio intermolecular potentials) as Δμ(w)(0) = 1206 ± 2 J/mol and ΔH(w)(0) = 1260 ± 12 J/mol. With these reference parameters and the VAS model, pure CO2 hydrate equilibrium pressure was predicted with an average absolute deviation of less than 3.2% from the experimental data. Predictions of the small cage occupancy ranged from 32 to 51%, and the large cage is more than 98% occupied. The intermolecular potentials were also tested by calculating the pure CO2 density and diffusion of CO2 in water using molecular dynamics simulations.

  4. Effect of crystal orientation on the phase diagrams, dielectric and piezoelectric properties of epitaxial BaTiO3 thin films

    Directory of Open Access Journals (Sweden)

    Huaping Wu


    Full Text Available The influence of crystal orientations on the phase diagrams, dielectric and piezoelectric properties of epitaxial BaTiO3 thin films has been investigated using an expanded nonlinear thermodynamic theory. The calculations reveal that crystal orientation has significant influence on the phase stability and phase transitions in the misfit strain-temperature phase diagrams. In particular, the (110 orientation leads to a lower symmetry and more complicated phase transition than the (111 orientation in BaTiO3 films. The increase of compressive strain will dramatically enhance the Curie temperature TC of (110-oriented BaTiO3 films, which matches well with previous experimental data. The polarization components experience a great change across the boundaries of different phases at room temperature in both (110- and (111-oriented films, which leads to the huge dielectric and piezoelectric responses. A good agreement is found between the present thermodynamics calculation and previous first-principles calculations. Our work provides an insight into how to use crystal orientation, epitaxial strain and temperature to tune the structure and properties of ferroelectrics.

  5. Effect of crystal orientation on the phase diagrams, dielectric and piezoelectric properties of epitaxial BaTiO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Huaping, E-mail:, E-mail: [Key Laboratory of E& M (Zhejiang University of Technology), Ministry of Education & Zhejiang Province, Hangzhou 310014 (China); State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, Dalian 116024 (China); Ma, Xuefu; Zhang, Zheng; Zeng, Jun; Chai, Guozhong [Key Laboratory of E& M (Zhejiang University of Technology), Ministry of Education & Zhejiang Province, Hangzhou 310014 (China); Wang, Jie [Department of Engineering Mechanics, School of Aeronautics and Astronautics, Zhejiang University, Hangzhou 310027 (China)


    The influence of crystal orientations on the phase diagrams, dielectric and piezoelectric properties of epitaxial BaTiO{sub 3} thin films has been investigated using an expanded nonlinear thermodynamic theory. The calculations reveal that crystal orientation has significant influence on the phase stability and phase transitions in the misfit strain-temperature phase diagrams. In particular, the (110) orientation leads to a lower symmetry and more complicated phase transition than the (111) orientation in BaTiO{sub 3} films. The increase of compressive strain will dramatically enhance the Curie temperature T{sub C} of (110)-oriented BaTiO{sub 3} films, which matches well with previous experimental data. The polarization components experience a great change across the boundaries of different phases at room temperature in both (110)- and (111)-oriented films, which leads to the huge dielectric and piezoelectric responses. A good agreement is found between the present thermodynamics calculation and previous first-principles calculations. Our work provides an insight into how to use crystal orientation, epitaxial strain and temperature to tune the structure and properties of ferroelectrics.

  6. Defining Condensed Phase Reactive Force Fields from ab Initio Molecular Dynamics Simulations: The Case of the Hydrated Excess Proton. (United States)

    Knight, Chris; Maupin, C Mark; Izvekov, Sergei; Voth, Gregory A


    In this report, a general methodology is presented for the parametrization of a reactive force field using data from a condensed phase ab initio molecular dynamics (AIMD) simulation. This algorithm allows for the creation of an empirical reactive force field that accurately reproduces the underlying ab initio reactive surface while providing the ability to achieve long-time statistical sampling for large systems not possible with AIMD alone. In this work, a model for the hydrated excess proton is constructed where the hydronium cation and proton hopping portions of the model are statistically force-matched to the results of Car-Parrinello Molecular Dynamics (CPMD) simulations. The flexible nature of the algorithm also allows for the use of the more accurate classical simple point-charge flexible water (SPC/Fw) model to describe the water-water interactions while utilizing the ab initio data to create an overall multistate molecular dynamics (MS-MD) reactive model of the hydrated excess proton in water. The resulting empirical model for the system qualitatively reproduces thermodynamic and dynamic properties calculated from the ab initio simulation while being in good agreement with experimental results and previously developed multistate empirical valence bond (MS-EVB) models. The present methodology, therefore, bridges the AIMD technique with the MS-MD modeling of reactive events, while incorporating key strengths of both.

  7. Phase diagram of the selenium-sulfur system in the pressure range 1 × 10-5-1 × 10-1 MPa (United States)

    Volodin, V. N.; Burabaeva, N. M.; Trebukhov, S. A.; Ersaiynova, A. A.


    The partial pressures of the components in the saturated vapor of the Se-S system were determined and presented as the temperature-concentration dependences. Based on these data, the boundaries of the melt-vapor phase transition at atmospheric pressure and in vacuum (1350, 100, and 10 Pa) were calculated. A complete phase diagram was constructed, which included the vapor-liquid equilibrium fields at atmospheric and low pressures, whose boundaries allowed us to determine the behavior of sulfur and selenium during distillation separation.

  8. System Cu-Rh-O: Phase diagram and thermodynamic properties of ternary oxides CuRhO2 and CuRh204


    Jacob, KT; Uda, T.; Waseda, Y; Okabe, TH


    An isothermal section of the phase diagram for the system Cu-Rh-O at 1273 K has been established by equilibration of samples representing eighteen different compositions, and phase identification after quenching by optical and scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive analysis of X-rays (EDX). In addition to the binary oxides Cu2O, CuO, and Rh2O3, two ternary oxides CuRhO2 and CuRh2O4 were identified. Both the ternary oxides were in equilibrium with me...

  9. Isothermal section of the ternary phase diagram U–Fe–Ge at 900 °C and its new intermetallic phases

    Energy Technology Data Exchange (ETDEWEB)

    Henriques, M.S., E-mail: [Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague (Czech Republic); CCTN, IST/CFMCUL, University of Lisbon, Nuclear and Technological Campus, P-2695-066 Bobadela (Portugal); Berthebaud, D.; Lignie, A.; El Sayah, Z.; Moussa, C.; Tougait, O. [Institut des Sciences Chimiques de Rennes, Chimie du Solide et Matériaux, Université Rennes 1, UMR CNRS 6226, 263 Avenue du Général Leclerc, 35042 Rennes (France); Havela, L. [Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 121 16 Prague (Czech Republic); Gonçalves, A.P. [CCTN, IST/CFMCUL, University of Lisbon, Nuclear and Technological Campus, P-2695-066 Bobadela (Portugal)


    Highlights: • Isothermal section of the U–Fe–Ge at 900 °C was investigated. • Ten ternary compounds and four significant solubility ranges were found. • Three new compounds and a solid solution were discovered. - Abstract: The isothermal section at 900 °C of the U–Fe–Ge ternary system was assessed using experimental results from X-ray diffraction and observations by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy chemical analysis. The phase diagram at this temperature is characterized by the formation of fourteen stable phases: four homogeneity ranges and ten intermetallic compounds. Among these, there is an extension of the binary compound UFe{sub 2} into the ternary system (UFe{sub 2−x}Ge{sub x,}x < 0.15), three ternary line compounds, U{sub 2}Fe{sub 17−x}Ge{sub x} (2 < x < 3.7), UFe{sub 1−x}Ge{sub 2} (0.58 < x < 0.78), UFe{sub 6+x}Ge{sub 6−x} (x < 0.7), and ten ternary stoichiometric compounds, U{sub 2}Fe{sub 3}Ge, U{sub 6}Fe{sub 16}Ge{sub 7}, UFe{sub 4}Ge{sub 2}, U{sub 6}Fe{sub 22}Ge{sub 13}, UFeGe, U{sub 3}Fe{sub 4}Ge{sub 4}, UFe{sub 2}Ge{sub 2}, U{sub 34}Fe{sub 3.32}Ge{sub 33}, U{sub 3}Fe{sub 2}Ge{sub 7}, and U{sub 9}Fe{sub 7}Ge{sub 24}.

  10. Simulation Activity Diagrams


    Ryan, John; Heavey, Cathal


    This paper presents a technique, Simulation Activity Diagrams (SAD), developed to lessen the modelling burden during the initial requirements gathering phases of a simulation project. The technique also allows the capture and visual communication of detailed information, to manufacturing personnel, which may otherwise be lost in detailed programming code.

  11. Hydrate morphology: Physical properties of sands with patchy hydrate saturation (United States)

    Dai, S.; Santamarina, J.C.; Waite, William F.; Kneafsey, T.J.


    The physical properties of gas hydrate-bearing sediments depend on the volume fraction and spatial distribution of the hydrate phase. The host sediment grain size and the state of effective stress determine the hydrate morphology in sediments; this information can be used to significantly constrain estimates of the physical properties of hydrate-bearing sediments, including the coarse-grained sands subjected to high effective stress that are of interest as potential energy resources. Reported data and physical analyses suggest hydrate-bearing sands contain a heterogeneous, patchy hydrate distribution, whereby zones with 100% pore-space hydrate saturation are embedded in hydrate-free sand. Accounting for patchy rather than homogeneous hydrate distribution yields more tightly constrained estimates of physical properties in hydrate-bearing sands and captures observed physical-property dependencies on hydrate saturation. For example, numerical modeling results of sands with patchy saturation agree with experimental observation, showing a transition in stiffness starting near the series bound at low hydrate saturations but moving toward the parallel bound at high hydrate saturations. The hydrate-patch size itself impacts the physical properties of hydrate-bearing sediments; for example, at constant hydrate saturation, we find that conductivity (electrical, hydraulic and thermal) increases as the number of hydrate-saturated patches increases. This increase reflects the larger number of conductive flow paths that exist in specimens with many small hydrate-saturated patches in comparison to specimens in which a few large hydrate saturated patches can block flow over a significant cross-section of the specimen.

  12. Hydrogen storage and carbon dioxide sequestration in TBAF semi-clathrate hydrates: Kinetics and evolution of hydrate-phase composition by in situ raman spectroscopy - Abstract -

    NARCIS (Netherlands)

    Torres Trueba, A.; Radoviæ, I.R.; Zevenbergen, J.F.; Kroon, M.C.; Peters, C.J.


    Carbon dioxide (CO2) represents almost one third of the emissions from the combustion of fossil fuels additionally, CO2 has been identified as the mayor contributor of global warming. Hydrogen (H2), on the other hand, due to its properties is considered a promising energy carrier. Clathrate hydrates

  13. Thermochemical properties of silver tellurides including empressite (AgTe) and phase diagrams for Ag-Te and Ag-Te-O (United States)

    Voronin, Mikhail V.; Osadchii, Evgeniy G.; Brichkina, Ekaterina A.


    This study compiles original experimental and literature data on the thermodynamic properties (ΔfG°, S°, ΔfH°) of silver tellurides (α-Ag2Te, β-Ag2Te, Ag1.9Te, Ag5Te3, AgTe) obtained by the method of solid-state galvanic cell with the RbAg4I5 and AgI solid electrolytes. The thermodynamic data for empressite (AgTe, pure fraction from Empress Josephine Mine, Colorado USA) have been obtained for the first time by the electrochemical experiment with the virtual reaction Ag + Te = AgTe. The Ag-Te phase diagrams in the T - x and log fTe2 (gas) - 1/ T coordinates have been refined, and the ternary Ag-Te-O diagrams with Ag-Te-TeO2 (paratellurite) composition range have been calculated.

  14. Role of lipid phase separations and membrane hydration in phospholipid vesicle fusion.

    NARCIS (Netherlands)

    Hoekstra, D.


    The relationship between lipid phase separation and fusion of small unilamellar phosphatidylserine-containing vesicles was investigated. The kinetics of phase separation were monitored by following the increase of self-quenching of the fluorescent phospholipid analogue

  15. Gas hydrate nucleation

    Energy Technology Data Exchange (ETDEWEB)



    The overall aim of the project was to gain more knowledge about the kinetics of gas hydrate formation especially the early growth phase. Knowledge of kinetics of gas hydrate formation is important and measurements of gas hydrate particle size and concentration can contribute to improve this knowledge. An experimental setup for carrying out experimental studies of the nucleation and growth of gas hydrates has been constructed and tested. Multi wavelength extinction (MWE) was the experimental technique selected for obtaining particle diameter and concentration. The principle behind MWE is described as well as turbidity spectrum analysis that in an initial stage of the project was considered as an alternative experimental technique. Details of the experimental setup and its operation are outlined. The measuring cell consists of a 1 litre horizontal tube sustaining pressures up to 200 bar. Laser light for particle size determination can be applied through sapphire windows. A description of the various auxiliary equipment and of another gas hydrate cell used in the study are given. A computer program for simulation and analysis of gas hydrate experiments is based on the gas hydrate kinetics model proposed by Skovborg and Rasmussen (1993). Initial measurements showed that knowledge of the refractive index of gas hydrates was important in order to use MWE. An experimental determination of the refractive index of methane and natural gas hydrate is described. The test experiments performed with MWE on collectives of gas hydrate particles and experiments with ethane, methane and natural gas hydrate are discussed. Gas hydrate particles initially seem to grow mainly in size and at latter stages in number. (EG) EFP-94; 41 refs.

  16. Determination of methane concentrations in water in equilibrium with sI methane hydrate in the absence of a vapor phase by in situ Raman spectroscopy (United States)

    Lu, W.; Chou, I.-Ming; Burruss, R.C.


    Most submarine gas hydrates are located within the two-phase equilibrium region of hydrate and interstitial water with pressures (P) ranging from 8 to 60 MPa and temperatures (T) from 275 to 293 K. However, current measurements of solubilities of methane in equilibrium with hydrate in the absence of a vapor phase are limited below 20 MPa and 283.15 K, and the differences among these data are up to 30%. When these data were extrapolated to other P-T conditions, it leads to large and poorly known uncertainties. In this study, in situ Raman spectroscopy was used to measure methane concentrations in pure water in equilibrium with sI (structure one) methane hydrate, in the absence of a vapor phase, at temperatures from 276.6 to 294.6 (??0.3) K and pressures at 10, 20, 30 and 40 (??0.4%) MPa. The relationship among concentration of methane in water in equilibrium with hydrate, in mole fraction [X(CH4)], the temperature in K, and pressure in MPa was derived as: X(CH4) = exp [11.0464 + 0.023267 P - (4886.0 + 8.0158 P)/T]. Both the standard enthalpy and entropy of hydrate dissolution at the studied T-P conditions increase slightly with increasing pressure, ranging from 41.29 to 43.29 kJ/mol and from 0.1272 to 0.1330 kJ/K ?? mol, respectively. When compared with traditional sampling and analytical methods, the advantages of our method include: (1) the use of in situ Raman signals for methane concentration measurements eliminates possible uncertainty caused by sampling and ex situ analysis, (2) it is simple and efficient, and (3) high-pressure data can be obtained safely. ?? 2007 Elsevier Ltd. All rights reserved.

  17. Effect of Difference in Fatty Acid Chain Lengths of Medium- Chain Lipids on Lipid/Surfactant/Water Phase Diagrams and Drug Solubility

    Directory of Open Access Journals (Sweden)

    Hetal N. Prajapati


    Full Text Available Lipids consisting of medium chain fatty acids are commonly used in the development of lipid-based selfemulsifying and self-microemulsifying drug delivery systems. However, no systematic approach to selecting one lipid over another has been reported in the literature. In this study, propylene glycol (PG monoester (PG monocaprylate, Capmul PG-8® and PG diester (PG dicaprylocaprate, Captex 200P® of C8-fatty acids were compared with PG monoester (PG monolaurate, Capmul PG-12® and PG diester (PG dilaurate, Capmul PG-2L® of C12-fatty acids with respect to their phase diagrams, and especially for their ability to form microemulsions in the presence of a common surfactant, Cremophor EL®, and water. The solubility of two model drugs, danazol and probucol, in the lipids and lipid/surfactant mixtures were also compared. The effect of the chain length of medium-chain fatty acids (C8 versus C12 on the phase diagrams of the lipids was minimal. Both shorter and longer chain lipids formed essentially similar microemulsion and emulsion regions in the presence of Cremophor EL® and water, although the C12-fatty acid esters formed larger gel regions in the phase diagrams than the C8-fatty acid esters. When monoesters were mixed with their respective diesters at 1:1 ratios, larger microemulsion regions with lower lipid particle sizes were observed compared to those obtained with individual lipids alone. While the solubility of both danazol and probucol increased greatly in all lipids studied, compared to their aqueous solubility, the solubility in C12-fatty acid esters was found to be lower than in C8-fatty acid esters when the lipids were used alone. This difference in solubility due to the difference in fatty acid chain length, practically disappeared when the lipids were combined with the surfactant.

  18. Micro-hydration of the MgNO3+ cation in the gas phase. (United States)

    Jagoda-Cwiklik, Barbara; Jungwirth, Pavel; Rulísek, Lubomír; Milko, Petr; Roithová, Jana; Lemaire, Joël; Maitre, Philippe; Ortega, Jean Michel; Schröder, Detlef


    Coordination complexes of the magnesium nitrate cation with water [MgNO(3)(H(2)O)(n)](+) up to n=7 are investigated by experiment and theory. The fragmentation patterns of [MgNO(3)(H(2)O)(n)](+) clusters generated via electrospray ionization indicate a considerable change in stability between n=3 and 4. Further, ion-molecule reactions of mass-selected [MgNO(3)(H(2)O)(n)](+) cations with D(2)O reveal the occurrence of consecutive replacement of water ligands by heavy water, and in this respect the complexes with n=4 and 5 are somewhat more reactive than their smaller homologs with n=1-3 as well as the larger clusters with n=6 and 7. For the latter two ions, the theory suggests the existence of isomers, such as complexes with monodentate nitrato ligands as well as solvent-separated ion pairs with a common solvation shell. The reactions observed and the ion thermochemistry are discussed in the context of ab initio calculations, which also reveal the structures of the various hydrated cation complexes.

  19. Steady and out-of-equilibrium phase diagram of a complex fluid at the nanolitre scale: combining microevaporation, confocal Raman imaging and small angle X-ray scattering. (United States)

    Daubersies, Laure; Leng, Jacques; Salmon, Jean-Baptiste


    We engineered specific microfluidic devices based on the pervaporation of water through a PDMS membrane, to formulate continuous and steady concentration gradients of a binary aqueous molecular mixture at the nanolitre scale. In the case of a model complex fluid (a triblock copolymer solution), we demonstrate that such a steady gradient crosses the phase diagram from pure water up to a succession of highly viscous mesophases. We then performed in situ spatially resolved measurements (confocal spectroscopy and small-angle X-ray scattering) to quantitatively measure the concentration profile and to determine the microstructure of the different textures. Within a single microfluidic channel, we thus screen quantitatively and continuously the phase diagram of a complex fluid. Beside, as such a gradient corresponds to an out-of-equilibrium regime, we also extract from the concentration measurement a precise estimate of the collective diffusion coefficient of the mixture as a function of the concentration. In the present case of the triblock copolymer, this transport coefficient features discontinuities at some phase boundaries, which have never been observed before.

  20. Soluble 1:1 complexes and insoluble 3:2 complexes - Understanding the phase-solubility diagram of hydrocortisone and γ-cyclodextrin. (United States)

    Schönbeck, Christian; Madsen, Tobias L; Peters, Günther H; Holm, René; Loftsson, Thorsteinn


    The molecular mechanisms underlying the drug-solubilizing properties of γ-cyclodextrin were explored using hydrocortisone as a model drug. The B S -type phase-solubility diagram of hydrocortisone with γ-cyclodextrin was thoroughly characterized by measuring the concentrations of hydrocortisone and γ-cyclodextrin in solution and the solid phase. The drug-solubilizer interaction was also studied by isothermal titration calorimetry from which a precise value of the 1:1 binding constant (K 11 =4.01mM -1 at 20°C) was obtained. The formation of water-soluble 1:1 complexes is responsible for the initial increase in hydrocortisone solubility while the precipitation of entities with a 3:2 ratio of γ-cyclodextrin:hydrocortisone is responsible for the plateau and the ensuing strong decrease in solubility once all solid hydrocortisone is used up. The complete phase-solubility diagram is well accounted for by a model employing the 1:1 binding constant and the solubility product of the precipitating 3:2 entity (K 32 S =5.51 mM 5 ). For such systems, a small surplus of γ-cyclodextrin above the optimum concentration may result in a significant decrease in drug solubility, and the implications for drug formulations are briefly discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Reentrant behaviors in the phase diagram of spin-1 planar ferromagnets with easy-axis single-ion anisotropy via the Devlin two-time Green function framework (United States)

    Mercaldo, M. T.; Rabuffo, I.; De Cesare, L.; Caramico D'Auria, A.


    The Devlin two-time Green function framework is used to investigate the role played by the easy-axis single-ion anisotropy on the phase diagram of (d > 2) -dimensional spin-1 planar ferromagnets which exhibit a magnetic-field-induced quantum phase transition (QPT). In this scheme, the exchange anisotropy terms in the equations of motion are treated at the Tyablikov decoupling level while the crystal field anisotropy contribution is handled exactly. The emerging key result is a reentrant structure of the phase diagram close to the quantum critical point for a well defined window of values of the single-ion anisotropy parameter. This experimentally interesting feature was recently recovered by employing the Anderson-Callen decoupling (ACD) which is considered to provide meaningful results only for small values of the single-ion anisotropy parameter. In this context, our findings suggest that the simplest ACD treatment offers the possibility to have, at least qualitatively, a correct physical scenario of quantum criticality close to a field-induced QPT avoiding the limiting mathematical difficulties involved in the Devlin scheme.

  2. Phase diagrams for the system water/butyric acid/propylene carbonate at T = 293.2-313.2 K and p = 101.3 kPa (United States)

    Shekarsaraee, Sina; Nahzomi, Hossein Taherpour; Nasiri-Touli, Elham


    Phase diagrams for the system water/butyric acid/propylene carbonate were plotted at T = 293.2, 303.2, 313.2 K and p = 101.3 kPa. Acidimetric titration and refractive index methods were used to determine tie-line data. Solubility data revealed that the studied system exhibits type-1 behavior of liquid-liquid equilibrium. The experimental data were regressed and acceptably correlated using the UNIQUAC and NRTL models. As a result, propylene carbonate is a suitable separating agent for aqueous mixture of butyric acid.

  3. Experimental and topological determination of the pressure-temperature phase diagram of morniflumate, a pharmaceutical ingredient with anti-inflammatory properties


    Barrio Casado, María del; Tamarit Mur, José Luis; Céolin, René; Robert, Benoit; Guechot, C.; Teulon, J.M.; Rietveld, Ivo B.


    The pressure-temperature phase diagram of morniflumate (niflumic acid ß-morpholinoethyl ester) has been obtained by high-pressure thermal analysis. In addition, calorimetric melting data (TI¿L = (348.1 ± 0.4) K and ¿HI¿L = (89 ± 2) J·g-1) and the specific volumes of the solid and the liquid state have been obtained under normal pressure. Comparison of the measured high-pressure melting data with the equilibrium curve obtained through the Clapeyron equation indicates that the initial slopes ar...

  4. High temperature and low field regime vortex phase diagram of in-situ prepared stainless steel sheathed MgB2 tapes (United States)

    Rajput, Suchitra


    A magnetic field-temperature vortex phase diagram has been proposed for MgB2 on the basis of magnetoresistance studies performed on an in-situ prepared stainless steel sheathed MgB2 tapes. Thermally activated flux flow (TAFF) behavior is analyzed using Arrhenius relation. Low dissipative part of magnetoresistance with temperature is well described by vortex glass theory. Above critical region, the resistive behavior is influenced by fluctuation conductivity. In addition, a considerable vortex liquid region below HC2 is also observed but TAFF region is found to be quite narrow.

  5. Phase diagrams and morphological evolution in wrapping of rod-shaped elastic nanoparticles by cell membrane: A two-dimensional study (United States)

    Yi, Xin; Gao, Huajian


    A fundamental understanding of cell-nanomaterial interaction is essential for biomedical diagnostics, therapeutics, and nanotoxicity. Here, we perform a theoretical analysis to investigate the phase diagram and morphological evolution of an elastic rod-shaped nanoparticle wrapped by a lipid membrane in two dimensions. We show that there exist five possible wrapping phases based on the stability of full wrapping, partial wrapping, and no wrapping states. The wrapping phases depend on the shape and size of the particle, adhesion energy, membrane tension, and bending rigidity ratio between the particle and membrane. While symmetric morphologies are observed in the early and late stages of wrapping, in between a soft rod-shaped nanoparticle undergoes a dramatic symmetry breaking morphological change while stiff and rigid nanoparticles experience a sharp reorientation. These results are of interest to the study of a range of phenomena including viral budding, exocytosis, as well as endocytosis or phagocytosis of elastic particles into cells.

  6. Magnetic-crystallographic p,T-phase diagram of Fe{sub 1.141}Te: A high-pressure neutron diffraction study

    Energy Technology Data Exchange (ETDEWEB)

    Joergensen, Jens-Erik [Department of Chemistry, Aarhus University (Denmark); Hansen, Thomas Christian [Institute Max von Laue-Paul Langevin, Grenoble (France)


    The crystal and magnetic structures of Fe{sub 1.141}Te have been studied by neutron powder diffraction in the temperature range from 5 to 106 K and pressures in the range from ambient to ∼2.7 GPa. The p,T-phase diagram contains three phases with monoclinic, orthorhombic, and tetragonal symmetry. The monoclinic phase was found to be stable for T phase is stable for T phase is stable at high temperatures and becomes stable down to the lowest measured temperatures for p > 2.16 GPa. The monoclinic phase shows commensurate bicollinear antiferromagnetic order with propagation vector k = (1/2 0 1/2), while the orthorhombic phase is incommensurately antiferromagnetically ordered with propagation vector k = (1/2-δ 0 1/2). The δ-parameter increases linearly with the pressure for 0.4 phase for p >or similar 2.1 GPa and temperatures less than ∝68 K, depending on the pressure. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Rheological study of an hydrate slurry as secondary two-phase refrigerant. Experimental results and modelling; Etude rheologique d'une suspension d'hydrates en tant que fluide frigoporteur diphasique: resultats experimentaux et modelisation

    Energy Technology Data Exchange (ETDEWEB)

    Darbouret, M.


    Secondary two-phase fluids are suspensions of solid crystals. Thanks to the melting latent heat, they present a great interest for cold transportation. Moreover, they are a mean of reducing the amount of classical refrigerant. In the refrigeration field, ice slurries are already used. The goal is now to extend this technology to other temperature ranges suitable for other applications like freezing or air-conditioning. For an air-conditioning application, a TBAB (Tetra-Butyl-Ammonium Bromide) aqueous solution is studied. Under atmospheric pressure and for positive temperatures, this solution crystallizes into ice-like compounds named 'hydrates'. First, the physical properties of the aqueous solution and its crystallisation conditions were studied. Two different types of hydrates can appear. The goal of the experimental set-up is to study the rheological behaviour of two-phase fluids. Slurries are made in brushed-surface heat exchanger and pumped into pipes where flow rates and pressure drops are measured. The rheological behaviour of TBAB hydrates slurries can be described using a Bingham fluid model. We highlight that the two rheological parameters, which are the apparent viscosity and the yield shear stress, depend on the volume fraction of crystal of course, but also on the hydrate type, and on the initial concentration of the solution. The yield shear stress is interpreted as the consequence of the Van der Waals inter-particle interaction forces. Finally, possible stratification effects are modelled with a finite difference method. The principle is to calculate particle concentration and velocity profiles following the flow of the slurry. Calculations are validated with experimental velocity profiles published by P. Reghem (2002). This model underlines the influence of the particle distribution in the pipe on pressure drops. (author)

  8. Thermodynamic Changes in the Coal Matrix - Gas - Moisture System Under Pressure Release and Phase Transformations of Gas Hydrates (United States)

    Dyrdin, V. V.; Smirnov, V. G.; Kim, T. L.; Manakov, A. Yu.; Fofanov, A. A.; Kartopolova, I. S.


    The physical processes occurring in the coal - natural gas system under the gas pressure release were studied experimentally. The possibility of gas hydrates presence in the inner space of natural coal was shown, which decomposition leads to an increase in the amount of gas passing into the free state. The decomposition of gas hydrates can be caused either by the seam temperature increase or the pressure decrease to lower than the gas hydrates equilibrium curve. The contribution of methane released during gas hydrates decomposition should be taken into account in the design of safe mining technologies for coal seams prone to gas dynamic phenomena.

  9. Hydration lubrication

    National Research Council Canada - National Science Library

    Klein, Jacob


    The hydration lubrication paradigm, whereby hydration layers are both strongly held by the charges they surround, and so can support large pressures without being squeezed out, and at the same time...

  10. Phase diagrams and free-energy landscapes for model spin-crossover materials with antiferromagnetic-like nearest-neighbor and ferromagnetic-like long-range interactions (United States)

    Chan, C. H.; Brown, G.; Rikvold, P. A.


    We present phase diagrams, free-energy landscapes, and order-parameter distributions for a model spin-crossover material with a two-step transition between the high-spin and low-spin states (a square-lattice Ising model with antiferromagnetic-like nearest-neighbor and ferromagnetic-like long-range interactions) [P. A. Rikvold et al., Phys. Rev. B 93, 064109 (2016), 10.1103/PhysRevB.93.064109]. The results are obtained by a recently introduced, macroscopically constrained Wang-Landau Monte Carlo simulation method [Phys. Rev. E 95, 053302 (2017), 10.1103/PhysRevE.95.053302]. The method's computational efficiency enables calculation of thermodynamic quantities for a wide range of temperatures, applied fields, and long-range interaction strengths. For long-range interactions of intermediate strength, tricritical points in the phase diagrams are replaced by pairs of critical end points and mean-field critical points that give rise to horn-shaped regions of metastability. The corresponding free-energy landscapes offer insights into the nature of asymmetric, multiple hysteresis loops that have been experimentally observed in spin-crossover materials characterized by competing short-range interactions and long-range elastic interactions.

  11. The phase diagrams of the mixed-spin ternary-alloy consisting of half-integer spins: Standard-random approach (United States)

    Albayrak, Erhan


    The ternary-alloy in the form ABpC1-p is investigated on the Bethe lattice with the odd numbered shells containing only A atoms (spin-1/2), while the even shells randomly containing either B (spin-3/2) or C (spin-5/2) atoms with different concentrations p and 1 - p, respectively. The phase diagrams are calculated on the (p ,kTc /JAB) and (R = |JAC | /JAB ,kTc /JAB) planes for given values of R and p, respectively, with the coordination numbers z = 3 , 4 , 5 and 6 by studying the thermal variations of the order-parameters. It is found that there exist a critical value of R, i.e. Rc ≅ 0.653, which is independent of z. In addition, the critical temperatures increase as z increases. The present work is an extension of the previous work [1] and it only differs from it by the implementation technique of randomness into the model. The obtained phase diagrams are in agreement with the site-dependent random case [1] except at low temperatures. On the other hand, there is an overall agreement with the literature.

  12. Electronic and magnetic phase diagram of β-Fe1.01Se with superconductivity at 36.7K under pressure (United States)

    Medvedev, S.; McQueen, T. M.; Troyan, I. A.; Palasyuk, T.; Eremets, M. I.; Cava, R. J.; Naghavi, S.; Casper, F.; Ksenofontov, V.; Wortmann, G.; Felser, C.


    The discovery of new high-temperature superconductors based on FeAs has led to a new `gold rush' in high-TC superconductivity. All of the new superconductors share the same common structural motif of FeAs layers and reach TC values up to 55K (ref. 2). Recently, superconductivity has been reported in FeSe (ref. 3), which has the same iron pnictide layer structure, but without separating layers. Here, we report the magnetic and electronic phase diagram of β-Fe1.01Se as a function of temperature and pressure. The superconducting transition temperature increases from 8.5 to 36.7K under an applied pressure of 8.9GPa. It then decreases at higher pressures. A marked change in volume is observed at the same time as TC rises, owing to a collapse of the separation between the Fe2Se2 layers. No static magnetic ordering is observed for the whole p-T phase diagram. We also report that at higher pressures (starting around 7GPa and completed at 38GPa), Fe1.01Se transforms to a hexagonal NiAs-type structure and exhibits non-magnetic behaviour.

  13. The use of Differential Scanning Calorimetry (DSC) to characterize phase diagrams of ionic mixtures of 1-n-butyl-3-methylimidazolium chloride and niobium chloride or zinc chloride

    Energy Technology Data Exchange (ETDEWEB)

    Alves, Melquizedeque B.; Umpierre, Alexandre P.; Santos Jr, Vianney O.; Soares, Valerio C.D. [Laboratorio de Materiais e Combustiveis - Instituto de Quimica da Universidade de Brasilia, C.P. 04478, CEP 70904-970, Brasilia, DF (Brazil); Dupont, Jairton [Laboratorio de Catalise Molecular - Instituto de Quimica da Universidade Federal do Rio Grande do Sul, C.P. 15003, CEP 91501-970, Porto Alegre, RS (Brazil); Rubim, Joel C. [Laboratorio de Materiais e Combustiveis - Instituto de Quimica da Universidade de Brasilia, C.P. 04478, CEP 70904-970, Brasilia, DF (Brazil); Suarez, Paulo A.Z., E-mail: [Laboratorio de Materiais e Combustiveis - Instituto de Quimica da Universidade de Brasilia, C.P. 04478, CEP 70904-970, Brasilia, DF (Brazil)


    The thermal behavior of the BMICl/NbCl{sub 5} and BMICl/ZnCl{sub 2} mixtures was investigated by DSC and correlated with previous studies using Raman spectroscopy. Combining both results, it was possible to built the phase diagram for these mixtures and suggest the formation of different compounds and the equilibria in the euthetic mixtures. The phase diagram of BMICl and NbCl{sub 5} mixture showed that probably only one compound is formed at X{sub NbCl5} = 0.50 (BMINbCl{sub 6}) and euthetic mixtures are present in the 0 {<=} X{sub NbCl5} {<=} 0.50 composition range. For the BMICl and ZnCl{sub 2}, four different compounds were detected: (BMI){sub 2}(ZnCl{sub 4}) for X{sub ZnCl2} = 0.35; (BMI){sub 2}(Zn{sub 2}Cl{sub 6}); (BMI){sub 2}(Zn{sub 3}Cl{sub 8}) and (BMI){sub 2}(Zn{sub 4}Cl{sub 10}) for X{sub ZnCl2} = 0.70, and between these isoplets euthetic mixtures are formed.

  14. Wing structure in the phase diagram of the Ising ferromagnet URhGe close to its tricritical point investigated by angle-resolved magnetization measurements (United States)

    Nakamura, Shota; Sakakibara, Toshiro; Shimizu, Yusei; Kittaka, Shunichiro; Kono, Yohei; Haga, Yoshinori; Pospíšil, Jiří; Yamamoto, Etsuji


    High-precision angle-resolved dc magnetization and magnetic torque studies were performed on a single-crystalline sample of URhGe, an orthorhombic Ising ferromagnet with the c axis being the magnetization easy axis, in order to investigate the phase diagram around the ferromagnetic (FM) reorientation transition in a magnetic field near the b axis. We have clearly detected a first-order transition in both the magnetization and the magnetic torque at low temperatures, and determined detailed profiles of the wing structure of the three-dimensional T -Hb-Hc phase diagram, where Hc and Hb denote the field components along the c and the b axes, respectively. The quantum wing critical points are located at μ0Hc˜±1.1 T and μ0Hb˜13.5 T. Two second-order transition lines at the boundaries of the wing planes rapidly tend to approach each other with increasing temperature up to ˜3 K. Just at the zero conjugate field (Hc=0 ), however, a signature of the first-order transition can still be seen in the field derivative of the magnetization at ˜4 K, indicating that the tricritical point exists in a rather high temperature region above 4 K. This feature of the wing plane structure is consistent with the theoretical expectation that three second-order transition lines merge tangentially at the tricritical point.

  15. Electronic and magnetic phase diagram of beta-Fe(1.01)Se with superconductivity at 36.7 K under pressure. (United States)

    Medvedev, S; McQueen, T M; Troyan, I A; Palasyuk, T; Eremets, M I; Cava, R J; Naghavi, S; Casper, F; Ksenofontov, V; Wortmann, G; Felser, C


    The discovery of new high-temperature superconductors based on FeAs has led to a new 'gold rush' in high-T(C) superconductivity. All of the new superconductors share the same common structural motif of FeAs layers and reach T(C) values up to 55 K (ref. 2). Recently, superconductivity has been reported in FeSe (ref. 3), which has the same iron pnictide layer structure, but without separating layers. Here, we report the magnetic and electronic phase diagram of beta-Fe(1.01)Se as a function of temperature and pressure. The superconducting transition temperature increases from 8.5 to 36.7 K under an applied pressure of 8.9 GPa. It then decreases at higher pressures. A marked change in volume is observed at the same time as T(C) rises, owing to a collapse of the separation between the Fe(2)Se(2) layers. No static magnetic ordering is observed for the whole p-T phase diagram. We also report that at higher pressures (starting around 7 GPa and completed at 38 GPa), Fe(1.01)Se transforms to a hexagonal NiAs-type structure and exhibits non-magnetic behaviour.

  16. Electronic and magnetic phase diagram of [Beta]Fe[subscript1.01]Se with superconductivity at 36.7 K under pressure

    Energy Technology Data Exchange (ETDEWEB)

    Medvedev, S.; McQueen, T.M.; Troyan, I.A.; Palasyuk, T.; Eremets, M.I.; Cava, R.J.; Naghavi, S.; Casper, F.; Ksenofontov, V.; Wortmann, G.; Felser, C.; (Paderborn); (MXPL-M); (Mainz); (Princeton)


    The discovery of new high-temperature superconductors based on FeAs has led to a new 'gold rush' in high-T{sub C} superconductivity. All of the new superconductors share the same common structural motif of FeAs layers and reach T{sub C} values up to 55 K. Recently, superconductivity has been reported in FeSe, which has the same iron pnictide layer structure, but without separating layers. Here, we report the magnetic and electronic phase diagram of {beta}-Fe{sub 1.01}Se as a function of temperature and pressure. The superconducting transition temperature increases from 8.5 to 36.7 K under an applied pressure of 8.9 GPa. It then decreases at higher pressures. A marked change in volume is observed at the same time as T{sub C} rises, owing to a collapse of the separation between the Fe{sub 2}Se{sub 2} layers. No static magnetic ordering is observed for the whole p-T phase diagram. We also report that at higher pressures (starting around 7 GPa and completed at 38 GPa), Fe{sub 1.01}Se transforms to a hexagonal NiAs-type structure and exhibits non-magnetic behavior.

  17. Combined high-pressure and high-temperature vibrational studies of dolomite: phase diagram and evidence of a new distorted modification (United States)

    Efthimiopoulos, I.; Jahn, S.; Kuras, A.; Schade, U.; Koch-Müller, M.


    A combined high-pressure mid-infrared absorption and Raman spectroscopy study on a natural CaMg0.98Fe0.02(CO3)2 dolomite sample was performed both at ambient and high temperatures. A pressure-temperature phase diagram was constructed for all the reported dolomite ambient- and high-pressure polymorphs. In addition, a local distortion of the ambient-pressure dolomite structure was identified close to 11 GPa, just before the transition toward the first known high-pressure phase. All the Clausius-Clapeyron slopes are found to be positive with similar magnitudes. Complementary first-principles calculations suggest a metastable nature of the high-pressure dolomite polymorphs. Finally, theoretical spectroscopy is used to interpret and discuss the observed changes in the measured vibrational spectra.

  18. A density-functional study of the phase diagram of cementite-type (Fe,Mn)3C at absolute zero temperature. (United States)

    Von Appen, Jörg; Eck, Bernhard; Dronskowski, Richard


    The phase diagram of (Fe(1-x) Mn(x))(3)C has been investigated by means of density-functional theory (DFT) calculations at absolute zero temperature. The atomic distributions of the metal atoms are not random-like as previously proposed but we find three different, ordered regions within the phase range. The key role is played by the 8d metal site which forms, as a function of the composition, differing magnetic layers, and these dominate the physical properties. We calculated the magnetic moments, the volumes, the enthalpies of mixing and formation of 13 different compositions and explain the changes of the macroscopic properties with changes in the electronic and magnetic structures by means of bonding analyses using the Crystal Orbital Hamilton Population (COHP) technique. 2010 Wiley Periodicals, Inc.

  19. The thermal behaviors and phase diagrams of the Ising-type endohedral fullerene with magnetic core and diluted magnetic shell (Core@Shell20) (United States)

    Kantar, Ersin


    We have carried out theoretical studies on Ising-type endohedral fullerene (EF) structure with a dopant magnetic atom encaged within the diluted magnetic spherical cage to examine the evolution in magnetic behaviors. We show how the thermal behaviors and phase diagrams of Ising-type EF are affected by diluted surface, crystal field and exchange couplings. We have used to investigate theoretically the effect of Hamiltonian parameters the effective field calculations within Ising model framework. The model Hamiltonian includes nearest neighbor ferromagnetic and antiferromagnetic center-surface (C-S) interaction as well as ferromagnetic surface interaction. We have shown that the system exhibits the first and second order phase transitions as well as tricritical point. In particular, the conditions for the occurrence of these reentrant and double reentrant behaviors are given explicitly.

  20. NaNO2 + NaNO3 phase diagram: New data from DSC and Raman spectroscopy

    DEFF Research Database (Denmark)

    Berg, Rolf W.; Kerridge, David H.; Larsen, Peter Halvor


    was detected close to 183 oC and a second one close to 160 oC. The latter was considered to be related to the nitrite component and probably arose from the ferroelec. to antiferroelec. or paraelec. transition of sodium nitrite. The change of slope of the maxima of some Raman lines with temp. also gave support...... with different sub-solidus curves. New Raman measurements and differential scanning calorimetry data on solidified mixts. of different compns. have provided support for a simple eutectic diagram with a solidus at 230 oC ranging from 0.25 to 0.80 in mole fraction of sodium nitrate. A sub-solidus transition...

  1. Rapid gas hydrate formation process (United States)

    Brown, Thomas D.; Taylor, Charles E.; Unione, Alfred J.


    The disclosure provides a method and apparatus for forming gas hydrates from a two-phase mixture of water and a hydrate forming gas. The two-phase mixture is created in a mixing zone which may be wholly included within the body of a spray nozzle. The two-phase mixture is subsequently sprayed into a reaction zone, where the reaction zone is under pressure and temperature conditions suitable for formation of the gas hydrate. The reaction zone pressure is less than the mixing zone pressure so that expansion of the hydrate-forming gas in the mixture provides a degree of cooling by the Joule-Thompson effect and provides more intimate mixing between the water and the hydrate-forming gas. The result of the process is the formation of gas hydrates continuously and with a greatly reduced induction time. An apparatus for conduct of the method is further provided.

  2. Hydration Leads to Efficient Reactions of the Carbonate Radical Anion with Hydrogen Chloride in the Gas Phase. (United States)

    Tang, Wai Kit; van der Linde, Christian; Siu, Chi-Kit; Beyer, Martin K


    The carbonate radical anion CO3•- is a key intermediate in tropospheric anion chemistry. Despite its radical character, only a small number of reactions have been reported in the literature. Here we investigate the gas-phase reactions of CO3•- and CO3•-(H2O) with HCl under ultrahigh vacuum conditions. Bare CO3•- forms OHCl•- with a rate constant of 4.2 × 10-12 cm3 s-1, which corresponds to an efficiency of only 0.4%. Hydration accelerates the reaction, and ligand exchange of H2O against HCl proceeds with a rate of 2.7 × 10-10 cm3 s-1. Quantum chemical calculations reveal that OHCl•- is best described as an OH• hydrogen bonded to Cl-, while the ligand exchange product is Cl-(HCO3•). Under tropospheric conditions, where CO3•-(H2O) is the dominant species, Cl-(HCO3•) is efficiently formed. These reactions must be included in models of tropospheric anion chemistry.

  3. High magnetic field phase diagram in electron-doped manganites La0.4Ca0.6Mn1−yCryO3 (United States)

    Lu, Chengliang; Hu, Ni; Yang, Ming; Xia, Shuangcheng; Wang, Haowen; Wang, Junfeng; Xia, Zhengcai; Liu, Jun-Ming


    We report the charge-order to ferromagnetic phase transition induced by pulsed high magnetic field and impurity doping effects in manganites La0.4Ca0.6(Mn1−yCry)O3 (0 ≤ y ≤ 0.2). Significant charge-order suppression and ferromagnetic tendency upon the Cr3+-doping are evidenced, and three different ground states are identified, namely the charge-order state, the phase separated state, and the spin-glass like state. Phase diagram in the H-y plane at 4.2 K is determined by the high magnetic field study, in which the charge-order and ferromagnetic phase boundary is clearly figured out. The critical magnetic field for melting the charge-order phase of La0.4Ca0.6MnO3 is revealed to reach up to 46 T at 4.2 K. Interestingly, distinct responses of the three states to the high magnetic field are observed, indicating the special physics regarding the charge order melting process in each state. The mechanism of the doping induced charge-order suppression and ferromagnetism promotion can be understood by the competition between the antiferromagnetic interaction of Cr-Mn and local enhancement of electron hopping by Cr3+. PMID:24811441

  4. High magnetic field phase diagram in electron-doped manganites La(0.4)Ca(0.6)Mn(1-y)Cr(y)O3. (United States)

    Lu, Chengliang; Hu, Ni; Yang, Ming; Xia, Shuangcheng; Wang, Haowen; Wang, Junfeng; Xia, Zhengcai; Liu, Jun-Ming


    We report the charge-order to ferromagnetic phase transition induced by pulsed high magnetic field and impurity doping effects in manganites La(0.4)Ca(0.6)(Mn(1-y)Cr(y))O3 (0 ≤ y ≤ 0.2). Significant charge-order suppression and ferromagnetic tendency upon the Cr(3+)-doping are evidenced, and three different ground states are identified, namely the charge-order state, the phase separated state, and the spin-glass like state. Phase diagram in the H-y plane at 4.2 K is determined by the high magnetic field study, in which the charge-order and ferromagnetic phase boundary is clearly figured out. The critical magnetic field for melting the charge-order phase of La(0.4)Ca(0.6)MnO3 is revealed to reach up to 46 T at 4.2 K. Interestingly, distinct responses of the three states to the high magnetic field are observed, indicating the special physics regarding the charge order melting process in each state. The mechanism of the doping induced charge-order suppression and ferromagnetism promotion can be understood by the competition between the antiferromagnetic interaction of Cr-Mn and local enhancement of electron hopping by Cr(3+).

  5. Construction of drug-polymer thermodynamic phase diagrams using Flory-Huggins interaction theory: identifying the relevance of temperature and drug weight fraction to phase separation within solid dispersions. (United States)

    Tian, Yiwei; Booth, Jonathan; Meehan, Elizabeth; Jones, David S; Li, Shu; Andrews, Gavin P


    Amorphous drug-polymer solid dispersions have the potential to enhance the dissolution performance and thus bioavailability of BCS class II drug compounds. The principle drawback of this approach is the limited physical stability of amorphous drug within the dispersion. Accurate determination of the solubility and miscibility of drug in the polymer matrix is the key to the successful design and development of such systems. In this paper, we propose a novel method, based on Flory-Huggins theory, to predict and compare the solubility and miscibility of drug in polymeric systems. The systems chosen for this study are (1) hydroxypropyl methylcellulose acetate succinate HF grade (HPMCAS-HF)-felodipine (FD) and (2) Soluplus (a graft copolymer of polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol)-FD. Samples containing different drug compositions were mixed, ball milled, and then analyzed by differential scanning calorimetry (DSC). The value of the drug-polymer interaction parameter χ was calculated from the crystalline drug melting depression data and extrapolated to lower temperatures. The interaction parameter χ was also calculated at 25 °C for both systems using the van Krevelen solubility parameter method. The rank order of interaction parameters of the two systems obtained at this temperature was comparable. Diagrams of drug-polymer temperature-composition and free energy of mixing (ΔG(mix)) were constructed for both systems. The maximum crystalline drug solubility and amorphous drug miscibility may be predicted based on the phase diagrams. Hyper-DSC was used to assess the validity of constructed phase diagrams by annealing solid dispersions at specific drug loadings. Three different samples for each polymer were selected to represent different regions within the phase diagram.

  6. From State Diagram to Class Diagram

    DEFF Research Database (Denmark)

    Borch, Ole; Madsen, Per Printz


    UML class diagram and Java source code are interrelated and Java code is a kind of interchange format. Working with UML state diagram in CASE tools, a corresponding xml file is maintained. Designing state diagrams is mostly performed manually using design patterns and coding templates - a time...... consuming process. This article demonstrates how to compile such a diagram into Java code and later, by reverse engineering, produce a class diagram. The process from state diagram via intermediate SAX parsed xml file to Apache Velocity generated Java code is described. The result is a fast reproducible...

  7. Non-Hermitian random matrix theory: summation of planar diagrams, the 'single-ring' theorem and the disc-annulus phase transition

    Energy Technology Data Exchange (ETDEWEB)

    Feinberg, Joshua [Physics Department, University of Haifa at Oranim, Tivon 36006 (Israel); Physics Department, Technion, Israel Institute of Technology, Haifa 32000 (Israel)


    I review aspects of work done in collaboration with A Zee and R Scalettar (1997 Nucl. Phys. B 504 579; 1997 Nucl. Phys. B 501 643; 2001 J. Math. Phys. 42 5718) on complex non-Hermitian random matrices. I open by explaining why the bag of tools used regularly in analysing Hermitian random matrices cannot be applied directly to analyse non-Hermitian matrices, and then introduce the method of Hermitization, which solves this problem. Then, for rotationally invariant ensembles, I derive a master equation for the average density of eigenvalues in the complex plane, in the limit of infinitely large matrices. This is achieved by resumming all the planar diagrams which appear in the perturbative expansion of the Hermitized Green function. Remarkably, this resummation can be carried out explicitly for any rotationally invariant ensemble. I prove that in the limit of infinitely large matrices, the shape of the eigenvalue distribution is either a disc or an annulus. This is the celebrated 'single-ring' theorem. Which of these shapes is realized is determined by the parameters (coupling constants) which determine the ensemble. By varying these parameters a phase transition may occur between the two possible shapes. I briefly discuss the universal features of this transition. As the analysis of this problem relies heavily on summation of planar Feynman diagrams, I make a special effort at presenting a pedagogical exposition of the diagrammatic method, which some readers may find useful.

  8. Ground-state phase diagram, fermionic entanglement and kinetically-induced frustration in a hybrid ladder with localized spins and mobile electrons (United States)

    Carvalho, R. C. P.; Pereira, M. S. S.; de Oliveira, I. N.; Strečka, J.; Lyra, M. L.


    We introduce an exactly solvable hybrid spin-ladder model containing localized nodal Ising spins and interstitial mobile electrons, which are allowed to perform a quantum-mechanical hopping between the ladder’s legs. The quantum-mechanical hopping process induces an antiferromagnetic coupling between the ladder’s legs that competes with a direct exchange coupling of the nodal spins. The model is exactly mapped onto the Ising spin ladder with temperature-dependent two- and four-spin interactions, which is subsequently solved using the transfer-matrix technique. We report the ground-state phase diagram and compute the fermionic concurrence to characterize the quantum entanglement between the pair of interstitial mobile electrons. We further provide a detailed analysis of the local spin ordering including the pair and four-spin correlation functions around an elementary plaquette, as well as, the local ordering diagrams. It is shown that a complex sequence of distinct local orderings and frustrated correlations takes place when the model parameters drive the investigated system close to a zero-temperature triple coexistence point.

  9. Contrasting P- T- t paths from the basement of the Tisia Unit (Slavonian Mts., NE Croatia): Application of quantitative phase diagrams and monazite age dating (United States)

    Horváth, Péter; Balen, Dražen; Finger, Fritz; Tomljenović, Bruno; Krenn, Erwin


    Medium-grade mica schists and intercalated paragneisses and amphibolites from the basement of the Tisia Unit, Slavonian Mountains., northeastern Croatia, contain complexly zoned garnets. At the Kutjevo locality, mica schists are characterised by garnets with Mn-rich cores and Ca-rich rims. Mn decreases steadily from core to rim and Ca increases abruptly. This is in contrast to the paragneisses and amphibolites which contain garnets with smoothly decreasing Ca from core to rim. Quantitative phase diagrams and garnet composition isopleths calculated from bulk rock analyses reveal that the Ca-poor garnet cores in the mica schists formed during an earlier event at 584-592 °C and 6.4-7.8 kbar. Ca-rich rims formed at conditions of 600-660 °C and 11-12 kbar — calculated using garnet isopleths and mineral thermobarometry. The paragneiss and amphibolite provide similar P- T information for the later peak event (ca. 650 °C, 10-12 kbar) but do not preserve a record of the earlier, lower P- T event and modelling shows that garnet was not stable at these conditions. Contrary to previous studies on this outcrop and rock type, no staurolite was observed and quantitative phase diagrams contoured for H 2O mode isopleths indicate that the rock did not cross staurolite-bearing fields during the retrograde P- T path. Mica schists from the Krndija locality contain zoned polyphase garnets. Phase diagram calculations reveal that Ca-rich garnet cores formed between 520 and 630 °C and 7-8 kbar. Rims have a lower Ca content and formed at considerably reduced pressures together with andalusite and staurolite at ca 530-570 °C and 3-4 kbar. Since both localities were traditionally considered to be part of the same tectono-metamorphic unit, evidence presented here clearly shows that this cannot be the case. EMP monazite ages are Variscan (350 Ma) in the Krndija mica schists and around pre- or early Variscan (440 Ma) in the Kutjevo mica schists. We therefore propose a more complex

  10. Magnetic phase diagram of Y{sub 1−x}Tb{sub x}Mn{sub 6}Sn{sub 6} compounds

    Energy Technology Data Exchange (ETDEWEB)

    Bykov, A.A., E-mail: [Petersburg Nuclear Physics Institute, National Research Centre Kurchatov Institute, Gatchina 188300 (Russian Federation); Chetverikov, Yu.O. [Petersburg Nuclear Physics Institute, National Research Centre Kurchatov Institute, Gatchina 188300 (Russian Federation); Moskvin, E.V. [Petersburg Nuclear Physics Institute, National Research Centre Kurchatov Institute, Gatchina 188300 (Russian Federation); St. Petersburg State University, St. Petersburg 199034 (Russian Federation); Pirogov, A.N. [Mikheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, Yekaterinburg 620990 (Russian Federation); Ural Federal University, Yekaterinburg 620002 (Russian Federation); Grigoriev, S.V. [Petersburg Nuclear Physics Institute, National Research Centre Kurchatov Institute, Gatchina 188300 (Russian Federation); St. Petersburg State University, St. Petersburg 199034 (Russian Federation)


    The Y{sub 1−x}Tb{sub x}Mn{sub 6}Sn{sub 6} compounds (x=0, 0.175, 0.2, 0.225, 0.25) were studied by small angle neutron scattering (SANS) and paramagnetic neutron spin echo. The YMn{sub 6}Sn{sub 6} compound is found to be a helimagnet in the whole temperature range below T{sub N}=310 K. Close to T{sub N} an additional peak of a Lorenz shape was observed at Q=0. The peak is thought to have originated from the ferromagnetic fluctuations of the magnetic Mn moment in the ab-plane of the hexagonal crystal structure. Compounds, in which Y is replaced by Tb, change their magnetic order with the increase of temperature: from easy cone ferromagnetic phase at low T through the helicoidal phase to the ferromagnetic fluctuation close to T{sub N}. Temperature-concentration phase diagram of Y{sub 1−x}Tb{sub x}Mn{sub 6}Sn{sub 6} is built on the basis of the obtained data. - Highlights: • The Y{sub 1−x}Tb{sub x}Mn{sub 6}Sn{sub 6} compounds (x=0, 0.175, 0.2, 0.225, 0.25) were studied by small angle neutron scattering (SANS) and paramagnetic neutron spin echo. • The YMn{sub 6}Sn{sub 6} compound is found to be a helimagnet in the whole temperature range below T{sub N}=310 K. • Close to T{sub N} an additional peak of a Lorenz shape was observed at Q=0. The peak is thought to have originated from the ferromagnetic fluctuations of the magnetic Mn moment in the ab-plane of the hexagonal crystal structure. • Compounds, in which Y is replaced by Tb, change their magnetic order with the increase of temperature: from easy cone ferromagnetic phase at low T through the helicoidal phase to the ferromagnetic fluctuation close to T{sub N}. • Temperature-concentration phase diagram of Y{sub 1−x}Tb{sub x}Mn{sub 6}Sn{sub 6} is built on the basis of the obtained data.

  11. H- T- J phase diagram and pinning mechanism in Ba 0.63K 0.37BiO 3- y single crystals (United States)

    Barilo, S. N.; Hall, D.; Gatalskaya, V. I.; Smirnova, T. V.; Shiryaev, S. V.; Crow, J. E.


    The H-T-J phase diagram of superconducting Ba 1- xK xBiO 3- y ( x=0.37, 0.41, 0.5) single crystals has been studied by means of SQUID and cantilever force magnetometry. Strong upward curvature of the Hc2 ( T) dependence confirms at least intermediate strength of the electron-phonon coupling in this 3D-superconductor family. The normalized critical current deduced from a cantilever force response is well described by collective pinning theory in the temperature range 0.01 Tcmechanism related to the spatial fluctuations of the carrier mean free path does not allow pronounced anomalous magnetization over the whole temperature range studied.

  12. Study of the Peculiarities of the Zn-Mn Phase Diagram and Their Effect on the Superplastic Behavior of Fine-Grained Zn-Mn Alloys (United States)

    Lolov, Martin; Djulgerov, Nikolai; Gyurov, Stoyko


    The part of binary manganese-zinc phase diagram (alloys containing up to 2% manganese) is analyzed and the expected compositions with increased plasticity are determined in this paper. A special attention is paid to the relation between the composition, microstructure, strain rate, and plasticity of the studied alloys. The mechanical behavior during plastic deformation is analyzed and the domains of strain rate are determined, where a superplastic deformation is expected. Superplastic deformation activation energy of the studied alloys is determined on the basis of the Arrhenius theory equation. It was found that the creep deformation of Zn-0.7% Mn alloy follows the power law, or is controlled by diffusion in grain boundaries, i.e., mechanism of deformation is Coble creep, while the deformation of Zn-1.2% Mn alloy is very low and does not correspond to any of diffusion processes in Zinc.

  13. Probing the effects of experimental conditions on the character of drug-polymer phase diagrams constructed using Flory-Huggins theory. (United States)

    Donnelly, Conor; Tian, Yiwei; Potter, Catherine; Jones, David S; Andrews, Gavin P


    Amorphous drug-polymer solid dispersions have been found to result in improved drug dissolution rates when compared to their crystalline counterparts. However, when the drug exists in the amorphous form it will possess a higher Gibb's free energy than its associated crystalline state and can recrystallize. Drug-polymer phase diagrams constructed through the application of the Flory Huggins (F-H) theory contain a wealth of information regarding thermodynamic and kinetic stability of the amorphous drug-polymer system. This study was aimed to evaluate the effects of various experimental conditions on the solubility and miscibility detections of drug-polymer binary system. Felodipine (FD)-Polyvinylpyrrolidone (PVP) K15 (PVPK15) and FD-Polyvinylpyrrolidone/vinyl acetate (PVP/VA64) were the selected systems for this research. Physical mixtures with different drug loadings were mixed and ball milled. These samples were then processed using Differential Scanning Calorimetry (DSC) and measurements of melting point (Tend) and glass transition (Tg) were detected using heating rates of 0.5, 1.0 and 5.0°C/min. The melting point depression data was then used to calculate the F-H interaction parameter (χ) and extrapolated to lower temperatures to complete the liquid-solid transition curves. The theoretical binodal and spinodal curves were also constructed which were used to identify regions within the phase diagram. The effects of polymer selection, DSC heating rate, time above parent polymer Tg and polymer molecular weight were investigated by identifying amorphous drug miscibility limits at pharmaceutically relevant temperatures. The potential implications of these findings when applied to a non-ambient processing method such as Hot Melt Extrusion (HME) are also discussed.

  14. Viral pathogenesis in diagrams

    National Research Council Canada - National Science Library

    Tremblay, Michel; Berthiaume, Laurent; Ackermann, Hans-Wolfgang


    .... The 268 diagrams in Viral Pathogenesis in Diagrams were selected from over 800 diagrams of English and French virological literature, including one derived from a famous drawing by Leonardo da Vinci...

  15. Magnetic phase diagram of Josephson vortices in Bi2Sr2CaCu2O2+y

    Indian Academy of Sciences (India)

    The doping effect is rejected not only in the lower boundary of 3D ordered phase, but also in the upper boundary. Above the upper boundary, the flow-resistance shows different behaviours, which may be related to the strength of the interlayer coupling of the JVs along the c-axis, and to the creation/annihilation of pancake ...

  16. Magnetic phase diagram of Josephson vortices in Bi2Sr2CaCu2O2+y

    Indian Academy of Sciences (India)

    can be observed close to 80 K and the starting field of the oscillations is almost independent of the temperature as shown in figure 5b. The maximum magnetic field of the periodic oscillations, which equals the upper boundary Hu of the 3D- ordered phase, suddenly decreases starting from about 76 K as shown in figure. 5c.

  17. Analysis of the Fe-Ce-O-C- M phase diagrams ( M = Ca, Mg, Al, Si) by constructing a component-solubility surface (United States)

    Mikhailov, G. G.; Makrovets, L. A.; Smirnov, L. A.; Dresvyankina, L. E.


    Analysis of the ternary phase diagrams of Ce2O3- and CeO2-containing oxide systems allowed us to find the oxide compounds that form during steel deoxidizing with cerium and with cerium together with aluminum, calcium, magnesium, or silicon. The temperature dependences of the equilibrium constants of formation of Ce2O3 oxides and Ce2O3 · Al2O3, Ce2O3 · 11Al2O3, Ce2O3 · 2SiO2, 7Ce2O3 · 9SiO2 and Ce2O3 · SiO2 compounds are found. Surfaces for the component solubility in metallic melts Fe-Al-Ce-O-C, Fe- Ca-Ce-O-C, Fe-Mg-Ce-O-C, and Fe-Si-Ce-O-C are constructed. Nonmetallic inclusions that form in the course of experimental melts of St20 steel after its deoxidizing with silicocalcium and rare-earth metal (REM)-containing master alloys in a ladle furnace after degassing are studied. Phase inhomogeneity of the inclusions is found. As a rule, they consist of phases classified into the following three groups: oxide-sulfide, sulfide-oxide, and multiphase oxide-sulfide melt. Calcium aluminates are found to be components of complex sulfide-oxide noncorrosive inclusions.

  18. Theoretical Phase Diagram for the Room-Temperature Electron-Hole Liquid in Photoexcited Quasi-Two-Dimensional Monolayer MoS2. (United States)

    Rustagi, Avinash; Kemper, Alexander F


    Strong correlations between electrons and holes can drive the existence of an electron-hole liquid (EHL) state, typically at high carrier densities and low temperatures. The recent emergence of quasi-two-dimensional (2D) monolayer transition metal dichalcogenides (TMDCs) provides ideal systems to explore the EHL state since ineffective screening of the out-of-plane field lines in these quasi-2D systems allows for stronger charge carrier correlations in contrast to conventional 3D bulk semiconductors and enables the existence of the EHL at high temperatures. Here we construct the phase diagram for the photoinduced first-order phase transition from a plasma of electron-hole pairs to a correlated EHL state in suspended monolayer MoS2. We show that the quasi-2D nature of monolayer TMDCs and the ineffective screening of the out-of-plane field lines allow for this phase transition to occur at and above room temperature, thereby opening avenues for studying many-body phenomena without the constraint of cryogenics.

  19. Magnetic phase diagram slightly below the saturation field in the stacked J1-J2 model in the square lattice with the JC interlayer coupling (United States)

    Ueda, Hiroaki

    We study the effect of adding interlayer coupling to the square lattice, J1-J2 Heisenberg model in high external magnetic field. In particular, we consider a cubic lattice formed from stacked J1-J2 layers, with interlayer exchange coupling JC. For the 2-dimensional model (JC = 0) it has been shown that a spin-nematic phase appears close to the saturation magnetic field for the parameter range - 0 . 4 0 . We determine the phase diagram for 3-dimensional model at high magnetic field by representing spin flips out of the saturated state as bosons, considering the dilute boson limit and using the Bethe-Salpeter equation to determine the first instability of the saturated paramagnet. Close to the highly frustrated point J2 /J1 0 . 5 , we find that the spin-nematic state is stable even for | JC /J1 | 1 . For larger values of J2 /J1 , interlayer coupling favors a broad, phase-separated region. Further increase of | JC | stabilizes a collinear antiferromagnet, which is selected via the order-by-disorder mechanism.

  20. Physical chemistry of nanostructured molecular sieves by the study of phase diagrams: the case of the cetyltrimethylammonium bromide-tetramethylammonium silicate-water system. (United States)

    Albuquerque, A; Vautier-Giongo, C; Pastore, H O


    A phase diagram for the system cetyltrimethylammonium bromide (CTAB)/tetramethylammonium silicate (TMASi)/water has been constructed in order to better understand the interactions between these precursors of the MCM-41 mesoporous molecular sieves. Three different CTAB concentration regions were analyzed: the dilute and semidilute regions, where simple surfactant species, such as monomers and spherical and nonspherical CTAB micelles, are found, and the concentrated region, involving liquid-crystalline phases. In the dilute and semidilute regions, the formation of a white nanostructured solid, having a hexagonal array similar to that found in MCM-41 materials, was observed. Precipitation of this solid requires some degree of surfactant monomer aggregation, which is favored by the presence of silicate anions. If micelles have already been formed, the material can be obtained at any CTAB concentration above a threshold concentration of silicate anions. These facts suggest that silicate anions have an important role in changing the aggregation and/or the shape of the surfactant aggregates. In the concentrated region, precipitation of the solid was not observed, but the presence of the silicate anions alter the characteristics of the liquid-crystalline phase formed by the surfactant. The system shows very complex and rich behavior and its investigation may be very useful in understanding the processes of nanostructured solid formation.