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Sample records for rutile phase equilibria

  1. Boron incorporation into rutile: phase equilibria and structural considerations

    International Nuclear Information System (INIS)

    Grey, I.E.; Li, C.; MacRae, C.M.; Bursill, L.A.

    1997-01-01

    Reduction of rutile in the presence of borate flux stabilised the rutile phase relative to reduced rutiles due to incorporation of boron from the flux. In the presence of borates the rutile phase is stabilised to oxygen fugacities that are lower by almost two orders of magnitude compared with fugacities at the limit of the single-phase rutile phase field in the pure Ti-O system. Boron incorporation is accompanied by reduction of titanium to the trivalent state, according to the charge compensation relation: 3Ti 4+ ≡ 3 Ti 3+ + B 3+ . Results of powder X-ray diffraction and transmission electron microscopy studies on samples prepared in the temperature range 1100 to 1300 deg C have been used to establish a model for boron incorporation. It is proposed that at the temperatures studied, local defects in boron doped rutile result from displacement of titanium atoms to adjacent interstitial sites coupled with occupation by boron of the triangular face of the vacated octahedral sites. This atomic grouping represents a small element of the TiBO 3 (calcite-type) structure. Annealing at a lower temperature results in ordering of the local defects to form (101) r planar intergrowths of rutile and calcite-type structures. 14 refs., 3 tabs., 8 figs

  2. Boron incorporation into rutile: phase equilibria and structural considerations

    Energy Technology Data Exchange (ETDEWEB)

    Grey, I.E.; Li, C.; MacRae, C.M. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), East Melbourne, VIC (Australia). Div of Minerals; Bursill, L.A. [Melbourne Univ., Parkville, VIC (Australia). School of Physics

    1997-06-01

    Reduction of rutile in the presence of borate flux stabilised the rutile phase relative to reduced rutiles due to incorporation of boron from the flux. In the presence of borates the rutile phase is stabilised to oxygen fugacities that are lower by almost two orders of magnitude compared with fugacities at the limit of the single-phase rutile phase field in the pure Ti-O system. Boron incorporation is accompanied by reduction of titanium to the trivalent state, according to the charge compensation relation: 3Ti{sup 4+}{identical_to} 3 Ti{sup 3+} + B{sup 3+}. Results of powder X-ray diffraction and transmission electron microscopy studies on samples prepared in the temperature range 1100 to 1300 deg C have been used to establish a model for boron incorporation. It is proposed that at the temperatures studied, local defects in boron doped rutile result from displacement of titanium atoms to adjacent interstitial sites coupled with occupation by boron of the triangular face of the vacated octahedral sites. This atomic grouping represents a small element of the TiBO{sub 3} (calcite-type) structure. Annealing at a lower temperature results in ordering of the local defects to form (101){sub r} planar intergrowths of rutile and calcite-type structures. 14 refs., 3 tabs., 8 figs.

  3. Phase equilibria basic principles, applications, experimental techniques

    CERN Document Server

    Reisman, Arnold

    2013-01-01

    Phase Equilibria: Basic Principles, Applications, Experimental Techniques presents an analytical treatment in the study of the theories and principles of phase equilibria. The book is organized to afford a deep and thorough understanding of such subjects as the method of species model systems; condensed phase-vapor phase equilibria and vapor transport reactions; zone refining techniques; and nonstoichiometry. Physicists, physical chemists, engineers, and materials scientists will find the book a good reference material.

  4. High temperature phase equilibria and phase diagrams

    CERN Document Server

    Kuo, Chu-Kun; Yan, Dong-Sheng

    2013-01-01

    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

  5. Solid-phase equilibria on Pluto's surface

    Science.gov (United States)

    Tan, Sugata P.; Kargel, Jeffrey S.

    2018-03-01

    Pluto's surface is covered by volatile ices that are in equilibrium with the atmosphere. Multicomponent phase equilibria may be calculated using a thermodynamic equation of state and, without additional assumptions, result in methane-rich and nitrogen-rich solid phases. The former is formed at temperature range between the atmospheric pressure-dependent sublimation and condensation points, while the latter is formed at temperatures lower than the sublimation point. The results, calculated for the observed 11 μbar atmospheric pressure and composition, are consistent with recent work derived from observations by New Horizons.

  6. Phase equilibria and phase structures of polymer blends

    International Nuclear Information System (INIS)

    Chalykh, Anatolii E; Gerasimov, Vladimir K

    2004-01-01

    Experimental, methodical and theoretical studies dealing with phase equilibria and phase structures of polymer blends are generalised. The general and specific features of the change in solubility of polymers with changes in the molecular mass and copolymer composition and upon the formation of three-dimensional cross-linked networks are described. The results of the effect of the prehistory on the phase structure and the non-equilibrium state of polymer blends are considered in detail.

  7. High-pressure fluid-phase equilibria: Experimental methods and systems investigated (2000-2004)

    DEFF Research Database (Denmark)

    Dohrn, Ralf; Peper, Stephanie; Fonseca, José

    2010-01-01

    As a part of a series of reviews, a compilation of systems for which high-pressure phase-equilibrium data were published between 2000 and 2004 is given. Vapor-liquid equilibria, liquid-liquid equilibria, vapor-liquid-liquid equilibria,solid-liquid equilibria, solid-vapor equilibria, solid-vapor-l...

  8. Phase equilibria of carbohydrates in polar solvents

    DEFF Research Database (Denmark)

    Jonsdottir, Svava Osk; Rasmussen, Peter

    1999-01-01

    A method for calculating interaction energies and interaction parameters with molecular mechanics methods is extended to predict solid-liquid equilibria (SLE) for saccharides in aqueous solution, giving results in excellent agreement with experimental values. Previously, the method has been shown...

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

    International Nuclear Information System (INIS)

    Beltran, Juan G.; Bruusgaard, Hallvard; Servio, Phillip

    2012-01-01

    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.

  10. PVA assisted low temperature anatase to rutile phase transformation (ART) and properties of titania nanoparticles

    International Nuclear Information System (INIS)

    Mondal, Shrabani; Madhuri, Rashmi; Sharma, Prashant K.

    2015-01-01

    Anatase to rutile phase transformation (ART) of titania nanoparticles is observed at very low temperature (180 °C) just by introducing polyvinyl alcohol (PVA) during co-precipitation followed by hydrothermal synthesis. The detailed investigations pertaining to the structural, optical and electrochemical properties of the nanosized titania and titania/PVA nanohybrid has been carried out. The crystallite size and crystal structure is confirmed using X-ray diffraction (XRD). Transmission electron microscopic (TEM) image reveals formation of spherical NPs in both the cases. Identification of functional groups is done using Fourier transform infrared spectroscopy (FTIR). The photoluminescence studies showed that emission slightly shifts towards higher wavelength side with remarkable decrease in intensity for TiO 2 /PVA nanocomposite (rutile samples). The remarkable decrease in PL intensity in TiO 2 /PVA nanocomposite (rutile samples) is explained considering the surface passivation during growth process. Ion transportation is monitored via Cyclic voltammetric (CV) and Electrochemical Impedance Spectroscopy (EIS) measurements. A significant enhancement of peak cathodic current in case of nanocomposite modified electrode is observed. It is assumed that TiO 2 /PVA (rutile) nanoparticles provided the conducting path for the electrons and hence enhanced the electrochemical reaction. - Graphical abstract: Present work reports anatase to rutile phase transformation (ART) of titania nanoparticles at very low temperature (180 °C) just by introducing polyvinyl alcohol (PVA) during co-precipitation followed by hydrothermal synthesis. - Highlights: • Low temperature phase transformation of TiO 2 nanoparticles from anatase to rutile. • Role of PVA in phase transformation. • Synthesis of spherical shaped uniformly distributed PVA capped TiO 2 NPs. • Explained the charge transfer process among anatase to rutile phase transformation via luminescence studies. • Enhanced

  11. Stability of equilibria for a two-phase osmosis model

    NARCIS (Netherlands)

    Lippoth, F.; Prokert, G.

    2012-01-01

    For a two-phase moving boundary problem modelling the motion of a semipermeable membrane by osmotic pressure and surface tension, we prove that the manifold of equilibria is locally exponentially attractive. Our method relies on maximal regularity results for parabolic systems with relaxation type

  12. Predicting phase equilibria in one-component systems

    Science.gov (United States)

    Korchuganova, M. R.; Esina, Z. N.

    2015-07-01

    It is shown that Simon equation coefficients for n-alkanes and n-alcohols can be modeled using critical and triple point parameters. Predictions of the phase liquid-vapor, solid-vapor, and liquid-solid equilibria in one-component systems are based on the Clausius-Clapeyron relation, Van der Waals and Simon equations, and the principle of thermodynamic similarity.

  13. Phase diagrams and heterogeneous equilibria a practical introduction

    CERN Document Server

    Predel, Bruno; Pool, Monte

    2004-01-01

    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. Extended Group Contribution Model for Polyfunctional Phase Equilibria

    DEFF Research Database (Denmark)

    Abildskov, Jens

    of physical separation processes. In a thermodynamic sense, design requires detailed knowledge of activity coefficients in the phases at equilibrium. The prediction of these quantities from a minimum of experimental data is the broad scope of this thesis. Adequate equations exist for predicting vapor......Material and energy balances and equilibrium data form the basis of most design calculations. While material and energy balances may be stated without much difficulty, the design engineer is left with a choice between a wide variety of models for describing phase equilibria in the design......-liquid equilibria from data on binary mixtures, composed of structurally simple molecules with a single functional group. More complex is the situation with mixtures composed of structurally more complicated molecules or molecules with more than one functional group. The UNIFAC method is extended to handle...

  15. On the rutile alpha-PbO"2-type phase boundary of TiO"2

    DEFF Research Database (Denmark)

    Olsen, J.S.; Gerward, Leif; Jiang, Jianzhong

    1999-01-01

    The high-pressure, high-temperature phase quilibria of TiO"2 have been studied with special emphasis on the rutile and alpha-PbO"2-type phases. It is found that the phase boundary, when plotted in a pressure-temperature diagram, changes from having a negative to having a positive slope...... with increasing temperature at about 6GPa and 850^oC. For nanophase material, the phase boundary is shifted towards lower pressure. The room-temperature bulk moduli are 210(120)GPa, 258(8)GPa and 290(20)GPa for rutile, the alpha-PbO"2-type phase and the baddeleyite-type phase, respectively....

  16. On phase equilibria in duplex stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Wessman, S. [Swerea KIMAB AB, Stockholm (Sweden); Pettersson, R. [Outokumpu Stainless AB, Avesta Research Centre, Avesta (Sweden); Hertzman, S. [Outokumpu Stainless Research Foundation, Stockholm (Sweden)

    2010-05-15

    The equilibrium conditions of four duplex stainless steels; Fe-23Cr-4.5Ni-0.1N, Fe-22Cr-5.5Ni-3Mo-0.17N, Fe-25Cr-7Ni-4Mo-0.27N and Fe-25Cr-7Ni-4Mo-1W-1.5Cu-0.27N were studied in the temperature region from 700 to 1000 C. Phase compositions were determined with SEM EDS and the phase fractions using image analysis on backscattered SEM images. The results showed that below 1000 C the steels develop an inverse duplex structure with austenite and sigma phase, of which the former is the matrix phase. With decreasing temperature, the microstructure will be more and more complex and finely dispersed. The ferrite is, for the higher alloyed steels, only stable above 1000 C and at lower temperatures disappears in favour of intermetallic phases. The major intermetallic phase is sigma phase with small amounts of chi phase, the latter primarily in high Mo and W grades. Nitrides, not a focus in this investigation, were present as rounded particles and acicular precipitates at lower temperatures. The results were compared to theoretical predictions using the TCFE5 and TCFE6 databases. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  17. Phase equilibria in chemical reactive fluid mixtures

    International Nuclear Information System (INIS)

    Maurer, Gerd

    2011-01-01

    Downstream processing is a major part of nearly all processes in the chemical industries. Most separation processes in the chemical (and related) industries for fluid mixtures are based on phase equilibrium phenomena. The majority of separation processes can be modelled assuming that chemical reactions are of no (or very minor) importance, i.e., assuming that the overall speciation remains unchanged during a separation process. However, there are also a large number of industrially important processes where the thermodynamic properties are influenced by chemical reactions. The phase equilibrium of chemical reactive mixtures has been a major research area of the author's group over nearly 40 years. In this contribution, three examples from that research are discussed. The first example deals with the vapour phase dimerisation of carboxylic acids and its consequences on phase equilibrium phenomena and phase equilibrium predictions. The second example deals with the solubility of sour gases (e.g., carbon dioxide and sulfur dioxide) in aqueous solutions of ammonia. That topic has been of interest for many years, e.g., in relation with the gasification and liquefaction of coal and, more recently, with the removal of carbon dioxide from flue gas in the 'chilled ammonia process'. The third example deals with phase equilibrium phenomena in aqueous solutions of polyelectrolytes. It deals with the phenomenon of 'counter ion condensation' and methods to model the Gibbs free energy of such solutions.

  18. Selective scanning tunneling microscope light emission from rutile phase of VO2.

    Science.gov (United States)

    Sakai, Joe; Kuwahara, Masashi; Hotsuki, Masaki; Katano, Satoshi; Uehara, Yoichi

    2016-09-28

    We observed scanning tunneling microscope light emission (STM-LE) induced by a tunneling current at the gap between an Ag tip and a VO2 thin film, in parallel to scanning tunneling spectroscopy (STS) profiles. The 34 nm thick VO2 film grown on a rutile TiO2 (0 0 1) substrate consisted of both rutile (R)- and monoclinic (M)-structure phases of a few 10 nm-sized domains at room temperature. We found that STM-LE with a certain photon energy of 2.0 eV occurs selectively from R-phase domains of VO2, while no STM-LE was observed from M-phase. The mechanism of STM-LE from R-phase VO2 was determined to be an interband transition process rather than inverse photoemission or inelastic tunneling processes.

  19. High-pressure fluid phase equilibria phenomenology and computation

    CERN Document Server

    Deiters, Ulrich K

    2012-01-01

    The book begins with an overview of the phase diagrams of fluid mixtures (fluid = liquid, gas, or supercritical state), which can show an astonishing variety when elevated pressures are taken into account; phenomena like retrograde condensation (single and double) and azeotropy (normal and double) are discussed. It then gives an introduction into the relevant thermodynamic equations for fluid mixtures, including some that are rarely found in modern textbooks, and shows how they can they be used to compute phase diagrams and related properties. This chapter gives a consistent and axiomatic approach to fluid thermodynamics; it avoids using activity coefficients. Further chapters are dedicated to solid-fluid phase equilibria and global phase diagrams (systematic search for phase diagram classes). The appendix contains numerical algorithms needed for the computations. The book thus enables the reader to create or improve computer programs for the calculation of fluid phase diagrams. introduces phase diagram class...

  20. Phase Equilibria Relationships of High-Tc Superconductors

    International Nuclear Information System (INIS)

    Wong-Ng, Winnie

    2011-01-01

    As an integral part of a R and D program partially supported by the Electricity Delivery and Energy Reliability Office of DOE, we have determined phase equilibria data and phase diagrams for the three generations of superconductor materials: 1st generation, (Bi,Pb)-Sr-Ca- Cu-O systems; 2nd generation, Ba-R-Cu-O systems (R=lanthanides and yttrium); and 3rd generation, MgB2 systems. Our studies involved bulk materials, single crystals and thin films. This report gives a summary of our accomplishments, a list of publications, and 15 selected journal publications.

  1. High temperature interdiffusion and phase equilibria in U-Mo

    International Nuclear Information System (INIS)

    Lundberg, L.B.

    1988-01-01

    Experimental data for interdiffusion and phase equilibria in the U-Mo system have been obtained over the temperature range 1400 to 1525 K as a fallout from compatibility experiments in which UO 2 was decomposed by lithium in closed molybdenum capsules. Composition-position, x-ray diffraction and microstructural data from the interdiffusion zones indicate that the intermediate phase U 2 Mo is found in this temperature range, contrary to the currently accepted equilibrium U-Mo phase diagram. The U-Mo interdiffusion data are in good agreement with published values. Inclusion of the U 2 Mo phase in a theoretical correlation of interdiffusion and phase equilibria data using Darken's equation indicate that high temperature interdiffusion of uranium and molybdenum follows the usual thermodynamic rules. Significant changes in the value of the thermodynamic based Darken factor near the U 2 Mo phase boundary on the high uranium side are indicated from both the new and published interdiffusion data. 9 refs., 10 figs., 3 tabs

  2. Phase equilibria of the Mo-Al-Ho ternary system

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yitai; Chen, Xiaoxian; Liu, Hao [Guangxi Univ., Nanning (China). College of Materials Science and Engineering; Guangxi Univ., Nanning (China). Guangxi Key Laboratory of Processing for Non-ferrous Metal and Featured Materials; Zhan, Yongzhong [Guangxi Univ., Nanning (China). College of Materials Science and Engineering; Guangxi Univ., Nanning (China). Guangxi Key Laboratory of Processing for Non-ferrous Metal and Featured Materials; Guangxi Univ., Nanning (China). Center of Ecological Collaborative Innovation for Aluminum Industry

    2017-08-15

    Investigation into the reactions and phase equilibria of transition metal elements (i.e. Mo, Zr, Cr, V and Ti), Al and rare earths is academically and industrially important for the development of both refractory alloys and lightweight high-temperature materials. In this work, the equilibria of the Mo-Al-Ho ternary system at 773 K have been determined by using X-ray powder diffraction and scanning electron microscopy equipped with energy dispersive X-ray analysis. A new ternary phase Al{sub 4}Mo{sub 2}Ho has been found and the other ternary phase Al{sub 43}Mo{sub 4}Ho{sub 6} is observed. Ten binary phases in the Al-Mo and Al-Ho systems, including Al{sub 17}Mo{sub 4} rather than Al{sub 4}Mo, have been determined to exist at 773 K. The homogeneity ranges of AlMo{sub 3} and Al{sub 8}Mo{sub 3} phase are 7.5 at.% and 1 at.%, respectively. According to the phase-disappearing method, the maximum solubility of Al in Mo is about 16 at.%.

  3. Phase equilibria in the niobium-vanadium-hydrogen system

    Energy Technology Data Exchange (ETDEWEB)

    Bethin, J. (Grumman Aerospace Corp., Bethpage, NY (USA)); Welch, D.O. (Brookhaven National Lab., Upton, NY (USA)); Pick, M.A. (Commission of the European Communities, Abingdon (UK). JET Joint Undertaking)

    1990-01-01

    The effect of vanadium additions to niobium on the metal-hydrogen phase equilibria has been studied. Measurements of the equilibrium H{sub 2}(D{sub 2}) pressure-composition-temperature isotherms for Nb{sub 1-x}V{sub x} alloys with 0{le}x<0.2 were used to determine the depression of the {alpha} - {alpha}' critical temperature with increasing vanadium concentration. A simple lattice-fluid model guided reduction of the data. Changes in the triple point temperature as well as the shift of the {zeta} {yields} {epsilon} phase transition were determined by differential scanning calorimetry measurements. A rapid overall depression was found, of the order of 7 K (at.% substituted V){sup -1}, for the metal-hydrogen (deuterium) phase boundary structure when compared with the Nb-H system in the hydrogen concentration range of interest. The results explain the enhanced terminal solubility of hydrogen in this system found previously by other authors. The changes in the phase equilibria are discussed in terms of the effect of hydrogen trapping and compared with the results of a cluster-variation calculation for random-field systems of previous authors, taking into account a distribution of H-site energies due to alloying. (author).

  4. Anatase-rutile phase transformation of titanium dioxide bulk material: a DFT + U approach

    International Nuclear Information System (INIS)

    Vu, Nam H; Le, Hieu V; Cao, Thi M; Pham, Viet V; Le, Hung M; Nguyen-Manh, Duc

    2012-01-01

    The anatase-rutile phase transformation of TiO 2 bulk material is investigated using a density functional theory (DFT) approach in this study. According to the calculations employing the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional with the Vanderbilt ultrasoft pseudopotential, it is suggested that the anatase phase is more energetically stable than rutile, which is in variance with the experimental observations. Consequently, the DFT + U method is employed in order to predict the correct structural stability in titania from electronic-structure-based total energy calculations. The Hubbard U term is determined by examining the band structure of rutile with various values of U from 3 to 10 eV. At U = 5 eV, a theoretical bandgap for rutile is obtained as 3.12 eV, which is in very good agreement with the reported experimental bandgap. Hence, we choose the DFT + U method (with U = 5 eV) to investigate the transformation pathway using the newly-developed solid-state nudged elastic band (ss-NEB) method, and consequently obtain an intermediate transition structure that is 9.794 eV per four-TiO 2 above the anatase phase. When the Ti-O bonds in the transition state are examined using charge density analysis, seven Ti-O bonds (out of 24 bonds in the anatase unit cell) are broken, and this result is in excellent agreement with a previous experimental study (Penn and Banfield 1999 Am. Miner. 84 871-6).

  5. Electronic structure and phase equilibria in ternary substitutional alloys

    International Nuclear Information System (INIS)

    Traiber, A.J.S.; Allen, S.M.; Waterstrat, R.M.

    1996-01-01

    A reliable, consistent scheme to study phase equilibria in ternary substitutional alloys based on the tight-binding approximation is presented. With electronic parameters from linear muffin-tin orbital calculations, the computed density of states and band structures compare well with those from more accurate abinitio calculations. Disordered alloys are studied within the tight-binding coherent-potential approximation extended to alloys; energetics of ordered systems are obtained through effective pair interactions computed with the general perturbation method; and partially ordered alloys are studied with a novel simplification of the molecular coherent-potential approximation combined with the general perturbation method. The formalism is applied to bcc-based Zr-Ru-Pd alloys which are promising candidates for medical implant devices. Using energetics obtained from the above scheme, we apply the cluster- variation method to study phase equilibria for particular pseudo- binary alloys and show that results are consistent with observed behavior of electronic specific heat coefficient with composition for Zr 0.5 (Ru, Pd) 0.5

  6. Metamorphism and partial melting of ordinary chondrites: Calculated phase equilibria

    Science.gov (United States)

    Johnson, T. E.; Benedix, G. K.; Bland, P. A.

    2016-01-01

    Constraining the metamorphic pressures (P) and temperatures (T) recorded by meteorites is key to understanding the size and thermal history of their asteroid parent bodies. New thermodynamic models calibrated to very low P for minerals and melt in terrestrial mantle peridotite permit quantitative investigation of high-T metamorphism in ordinary chondrites using phase equilibria modelling. Isochemical P-T phase diagrams based on the average composition of H, L and LL chondrite falls and contoured for the composition and abundance of olivine, ortho- and clinopyroxene, plagioclase and chromite provide a good match with values measured in so-called equilibrated (petrologic type 4-6) samples. Some compositional variables, in particular Al in orthopyroxene and Na in clinopyroxene, exhibit a strong pressure dependence when considered over a range of several kilobars, providing a means of recognising meteorites derived from the cores of asteroids with radii of several hundred kilometres, if such bodies existed at that time. At the low pressures (recorders of peak conditions. The intersection of isopleths of these variables may allow pressures to be quantified, even at low P, permitting constraints on the minimum size of parent asteroid bodies. The phase diagrams predict the onset of partial melting at 1050-1100 °C by incongruent reactions consuming plagioclase, clinopyroxene and orthopyroxene, whose compositions change abruptly as melting proceeds. These predictions match natural observations well and support the view that type 7 chondrites represent a suprasolidus continuation of the established petrologic types at the extremes of thermal metamorphism. The results suggest phase equilibria modelling has potential as a powerful quantitative tool in investigating, for example, progressive oxidation during metamorphism, the degree of melting and melt loss or accumulation required to produce the spectrum of differentiated meteorites, and whether the onion shell or rubble pile

  7. Phase equilibria and molecular interaction studies on (naphthols + vanillin) systems

    International Nuclear Information System (INIS)

    Gupta, Preeti; Agrawal, Tanvi; Das, Shiva Saran; Singh, Nakshatra Bahadur

    2012-01-01

    Highlights: ► Phase equilibria of (naphthol + vanillin) systems have been studied for the first time. ► Eutectic type phase diagrams are obtained. ► Eutectic mixtures show nonideal behaviour. ► There is a weak molecular interaction between the components in the eutectic mixtures. ► α-Naphthol–vanillin eutectic is more stable as compared to β-naphthol–vanillin. - Abstract: Phase equilibria between (α-naphthol + vanillin) and (β-naphthol + vanillin) systems have been studied by thaw-melt method and the results show the formation of simple eutectic mixtures. Crystallization velocities of components and eutectic mixtures were determined at different stages under cooling. With the help of differential scanning calorimeter (DSC), the enthalpy of fusion of components and eutectic mixtures was determined and from the values excess thermodynamic functions viz., excess Gibbs free energy (G E ), excess entropy (S E ), excess enthalpy (H E ) of hypo-, hyper- and eutectic mixtures were calculated. Flexural strength measurements were made in order to understand the non-ideal nature of eutectics. FT-IR spectral studies indicate the formation of hydrogen bond in the eutectic mixture. Anisotropic and isotropic microstructural studies of components, hypo-, hyper- and eutectic mixtures were made. Jackson’s roughness parameter was calculated and found to be greater than 2 suggesting the faceted morphology with irregular structures. The overall results have shown that there is a weak molecular interaction between the components in the eutectic mixtures and the (α-naphthol + vanillin) eutectic is more stable as compared to the (β-naphthol + vanillin) eutectic system.

  8. Phase Equilibria of Sn-Co-Cu Ternary System

    Science.gov (United States)

    Chen, Yu-Kai; Hsu, Chia-Ming; Chen, Sinn-Wen; Chen, Chih-Ming; Huang, Yu-Chih

    2012-10-01

    Sn-Co-Cu ternary alloys are promising lead-free solders, and isothermal sections of Sn-Co-Cu phase equilibria are fundamentally important for the alloys' development and applications. Sn-Co-Cu ternary alloys were prepared and equilibrated at 523 K, 1073 K, and 1273 K (250 °C, 800 °C, and 1000 °C), and the equilibrium phases were experimentally determined. In addition to the terminal solid solutions and binary intermetallic compounds, a new ternary compound, Sn3Co2Cu8, was found. The solubilities of Cu in the α-CoSn3 and CoSn2 phases at 523 K (250 °C) are 4.2 and 1.6 at. pct, respectively, while the Cu solubility in the α-Co3Sn2 phase is as high as 20.0 at. pct. The Cu solubility increases with temperature and is around 30.0 at. pct in the β-Co3Sn2 at 1073 K (800 °C). The Co solubility in the η-Cu6Sn5 phase is also significant and is 15.5 at. pct at 523 K (250 °C).

  9. Raman-scattering observation of the rutile-to-CaCl2 phase transition in RuO2

    International Nuclear Information System (INIS)

    Rosenblum, S.S.; Weber, W.H.; Chamberland, B.L.

    1997-01-01

    Using a diamond-anvil cell, we have probed the pressure-induced rutile-to-CaCl 2 ferroelastic phase transition in RuO 2 with Raman spectroscopy. The transition is marked by a splitting of the degenerate E g mode of the rutile phase into two nondegenerate components and by an abrupt change in the Grueneisen parameters for all the phonons. The behavior of this splitting shows good agreement with Landau close-quote s theory for a second-order phase transition, application of which yields a transition pressure of 11.8±0.3 GPa. copyright 1997 The American Physical Society

  10. A fast-reliable methodology to estimate the concentration of rutile or anatase phases of TiO2

    Directory of Open Access Journals (Sweden)

    A. R. Zanatta

    2017-07-01

    Full Text Available Titanium-dioxide (TiO2 is a low-cost, chemically inert material that became the basis of many modern applications ranging from, for example, cosmetics to photovoltaics. TiO2 exists in three different crystal phasesRutile, Anatase and, less commonly, Brookite − and, in most of the cases, the presence or relative amount of these phases are essential to decide the TiO2 final application and its related efficiency. Traditionally, X-ray diffraction has been chosen to study TiO2 and provides both the phases identification and the Rutile-to-Anatase ratio. Similar information can be achieved from Raman scattering spectroscopy that, additionally, is versatile and involves rather simple instrumentation. Motivated by these aspects this work took into account various TiO2 Rutile+Anatase powder mixtures and their corresponding Raman spectra. Essentially, the method described here was based upon the fact that the Rutile and Anatase crystal phases have distinctive phonon features, and therefore, the composition of the TiO2 mixtures can be readily assessed from their Raman spectra. The experimental results clearly demonstrate the suitability of Raman spectroscopy in estimating the concentration of Rutile or Anatase in TiO2 and is expected to influence the study of TiO2-related thin films, interfaces, systems with reduced dimensions, and devices like photocatalytic and solar cells.

  11. Thermodynamics and phase equilibria of ternary systems relevant to contact materials for compound semiconductors

    International Nuclear Information System (INIS)

    Ipser, H.; Richter, K.; Micke, K.

    1997-01-01

    In order to investigate the stability of ohmic contacts to compound semiconductors, it is necessary to know the phase equilibria in the corresponding multi-component systems. We are currently studying the phase equilibria and thermophysical properties of several ternary systems which are of interest in view of the use of nickel, palladium and platinum as contact materials for GaSb and InSb compound semiconductors: Ga-Ni-Sb, In-Ni-Sb, Ga-Pd-Sb and Ga-Pt-Sb. Phase equilibria are investigated by thermal analyses, X-ray powder diffraction methods as well as electron microprobe analysis. Thermodynamic properties are derived from vapour pressure measurements using an isopiestic method. It is planned to combine all information on phase equilibria and thermochemistry for the ternary and the limiting binary systems to perform an optimization of the ternary systems by computer calculations using standard software. (author)

  12. Phase equilibria constraints on models of subduction zone magmatism

    Science.gov (United States)

    Myers, James D.; Johnston, Dana A.

    Petrologic models of subduction zone magmatism can be grouped into three broad classes: (1) predominantly slab-derived, (2) mainly mantle-derived, and (3) multi-source. Slab-derived models assume high-alumina basalt (HAB) approximates primary magma and is derived by partial fusion of the subducting slab. Such melts must, therefore, be saturated with some combination of eclogite phases, e.g. cpx, garnet, qtz, at the pressures, temperatures and water contents of magma generation. In contrast, mantle-dominated models suggest partial melting of the mantle wedge produces primary high-magnesia basalts (HMB) which fractionate to yield derivative HAB magmas. In this context, HMB melts should be saturated with a combination of peridotite phases, i.e. ol, cpx and opx, and have liquid-lines-of-descent that produce high-alumina basalts. HAB generated in this manner must be saturated with a mafic phase assemblage at the intensive conditions of fractionation. Multi-source models combine slab and mantle components in varying proportions to generate the four main lava types (HMB, HAB, high-magnesia andesites (HMA) and evolved lavas) characteristic of subduction zones. The mechanism of mass transfer from slab to wedge as well as the nature and fate of primary magmas vary considerably among these models. Because of their complexity, these models imply a wide range of phase equilibria. Although the experiments conducted on calc-alkaline lavas are limited, they place the following limitations on arc petrologic models: (1) HAB cannot be derived from HMB by crystal fractionation at the intensive conditions thus far investigated, (2) HAB could be produced by anhydrous partial fusion of eclogite at high pressure, (3) HMB liquids can be produced by peridotite partial fusion 50-60 km above the slab-mantle interface, (4) HMA cannot be primary magmas derived by partial melting of the subducted slab, but could have formed by slab melt-peridotite interaction, and (5) many evolved calc

  13. Phase Equilibria and Compressibility of bastnaesite-(La)

    Science.gov (United States)

    Rowland, R. L., II; Burnley, P. C.

    2015-12-01

    Bastnaesite (Ce,La,Y)CO3(F,OH) is a rare earth element (REE) bearing ore mineral. REEs are more common in the Earth's crust than precious metals like gold or platinum, but are not commonly concentrated in economically viable ore deposits. For over a decade, China has been the world's leading supplier of REEs. Recent export restrictions from China have necessitated the search for new deposits. Determining basic material properties such as phase equilibria and the equation of state for bastnaesite helps in understanding the processes that form REE ore deposits and thereby assist in locating new deposits. For this study we focus on the lanthanum-fluoride variant of bastnaesite (LaCO3F) since it can be easily synthesized in the laboratory. Previous work by others determined that in both open and closed systems at atmospheric pressure bastnaesite decomposes to lanthanum oxyfluoride and carbon dioxide (LaOF + CO2) above 325°C; at 100 MPa bastnaesite decomposes above 860°C (Hsu, 1992). Using a Griggs-type modified piston cylinder apparatus, we pressurized samples of synthetic bastnaesite-(La) to conditions ranging from 250 MPa to 1.2 GPa, and then subjected each sample to constant temperatures ranging from 700°C to 1050°C for a minimum of five hours. We then analyzed the samples with X-ray powder diffraction to identify phases present and determined that bastnaesite-(La) is stable at 250 MPa up to approximately 800°C and at 1.0 GPa up to approximately 900°C. Reversal experiments are underway. In order to develop an equation of state for bastnaesite-(La), we studied single crystals via monochromatic synchrotron X-ray diffraction in the diamond anvil cell at HPCAT (Sector 16), Advanced Photon Source (APS), Argonne National Laboratory. Measurements were made at pressures ranging from ambient to nearly 4 GPa. From these diffraction patterns, we determine the structure of bastnaesite-(La), and the change in unit cell volume as a function of pressure can be fit to a Birch

  14. Combined toxicity of two crystalline phases (anatase and rutile) of Titania nanoparticles towards freshwater microalgae: Chlorella sp

    Energy Technology Data Exchange (ETDEWEB)

    Iswarya, V.; Bhuvaneshwari, M.; Alex, Sruthi Ann; Iyer, Siddharth; Chaudhuri, Gouri [Centre for Nanobiotechnology, VIT University, Vellore (India); Chandrasekaran, Prathna Thanjavur [Department of Materials Engineering, Indian Institute of Science, Bangalore (India); Bhalerao, Gopalkrishna M.; Chakravarty, Sujoy [UGC-DAE CSR, Kalpakkam Node, Kokilamedu (India); Raichur, Ashok M. [Department of Materials Engineering, Indian Institute of Science, Bangalore (India); Chandrasekaran, N. [Centre for Nanobiotechnology, VIT University, Vellore (India); Mukherjee, Amitava, E-mail: amit.mookerjea@gmail.com [Centre for Nanobiotechnology, VIT University, Vellore (India)

    2015-04-15

    Highlights: • Toxicity of two crystalline phases of titania NPs on freshwater microalgae studied. • (Anatase, Rutile) mixture showed additive and antagonistic effect on microalgae. • Rutile had more colloidal stability than anatase and binary mixtures. • ROS generation varied with the crystallinity of the NPs. • Ultrastructural damages observed in TEM images. - Abstract: In view of the increasing usage of anatase and rutile crystalline phases of titania NPs in the consumer products, their entry into the aquatic environment may pose a serious risk to the ecosystem. In the present study, the possible toxic impact of anatase and rutile nanoparticles (individually and in binary mixture) was investigated using freshwater microalgae, Chlorella sp. at low exposure concentrations (0.25, 0.5 and 1 mg/L) in freshwater medium under UV irradiation. Reduction of cell viability as well as a reduction in chlorophyll content were observed due to the presence of NPs. An antagonistic effect was noted at certain concentrations of binary mixture such as (0.25, 0.25), (0.25, 0.5), and (0.5, 0.5) mg/L, and an additive effect for the other combinations, (0.25, 1), (0.5, 0.25), (0.5, 1), (1, 0.25), (1, 0.5), and (1, 1) mg/L. The hydrodynamic size analyses in the test medium revealed that rutile NPs were more stable in lake water than the anatase and binary mixtures [at 6 h, the sizes of anatase (1 mg/L), rutile NPs (1 mg/L), and binary mixture (1, 1 mg/L) were 948.83 ± 35.01 nm, 555.74 ± 19.93 nm, and 1620.24 ± 237.87 nm, respectively]. The generation of oxidative stress was found to be strongly dependent on the crystallinity of the nanoparticles. The transmission electron microscopic images revealed damages in the nucleus and cell membrane of algal cells due to the interaction of anatase NPs, whereas rutile NPs were found to cause chloroplast and internal organelle damages. Mis-shaped chloroplasts, lack of nucleus, and starch-pyrenoid complex were noted in binary

  15. Using a Differential Scanning Calorimeter to Teach Phase Equilibria to Students of Igneous and Metamorphic Petrology

    Science.gov (United States)

    Maria, Anton H.; Millam, Evan L.; Wright, Carrie L.

    2011-01-01

    As an aid for teaching phase equilibria to undergraduate students of igneous and metamorphic petrology, we have designed a laboratory exercise that allows them to create a phase diagram from data produced by differential scanning calorimetry. By preparing and analyzing samples of naphthalene and phenanthrene, students acquire hands-on insight into…

  16. New investigation of phase equilibria in the system Al-Cu-Si.

    Science.gov (United States)

    Ponweiser, Norbert; Richter, Klaus W

    2012-01-25

    The phase equilibria and invariant reactions in the system Al-Cu-Si were investigated by a combination of optical microscopy, powder X-ray diffraction (XRD), differential thermal analysis (DTA) and electron probe micro analysis (EPMA). Isothermal phase equilibria were investigated within two isothermal sections. The isothermal section at 500 °C covers the whole ternary composition range and largely confirms the findings of previous phase diagram investigations. The isothermal section at 700 °C describes phase equilibria only in the complex Cu-rich part of the phase diagram. A new ternary compound τ was found in the region between (Al,Cu)-γ(1) and (Cu,Si)-γ and its solubility range was determined. The solubility of Al in κ-CuSi was found to be extremely high at 700 °C. In contrast, no ternary solubility in the β-phase of Cu-Al was found, although this phase is supposed to form a complete solid solution according to previous phase diagram assessments. Two isopleths, at 10 and 40 at.% Si, were investigated by means of DTA and a partial ternary reaction scheme (Scheil diagram) was constructed, based on the current work and the latest findings in the binary systems Al-Cu and Cu-Si. The current study shows that the high temperature equilibria in the Cu-rich corner are still poorly understood and additional studies in this area would be favorable.

  17. Synthetic Rutile

    International Nuclear Information System (INIS)

    Burastero, J.

    1975-01-01

    This work is about the laboratory scale investigation of the conditions in the rutile synthetic production from one me nita in Aguas Dulces reservoir. The iron mineral is chlorinated and volatilized selectively leaving a residue enriched in titanium dioxide which can be used as a substitute of rutile mineral

  18. Development and testing of a new apparatus for the measurement of high-pressure low-temperature phase equilibria

    DEFF Research Database (Denmark)

    Fonseca, José M.S.; von Solms, Nicolas

    2012-01-01

    A new apparatus for the study of high-pressure phase equilibria at low temperatures using an analytical method was designed, assembled and tested. The apparatus was specially developed for the study of multi-phase equilibria in systems containing hydrocarbons, water and hydrate inhibitors, at tem...

  19. Proportion of influence phases anatase and rutile TiO_2 in the photoluminescence 538 nm emission wavelength

    International Nuclear Information System (INIS)

    Araujo, D.S.; Diniz, V.C.S.; Araujo, P.M.A.G.; Costa, A.C.F.M.; Viana, R.S.; Junior, S.A.

    2016-01-01

    TiO2 is one of the most studied materials in the technology area, especially in photoluminescent applications involving catalysts from the biosensor. Therefore, we propose to obtain the Pechini method TiO_2 molar ratio of citric acid/metal ions of 3:1 and 4:1 in order to investigate the influence of the proportion of anatase and rutile phases with the photoluminescence excitation wavelength of 538nm emission. The samples were characterized by X-ray diffraction, thermal analysis and excitation spectroscopy. The results indicate the presence of two phases, with a proportion of 78.99 and 83.58 and 21.01% of anatase and rutile 16.42%, density 3.82 and 3.70 g/cm"3 and excitement in length wave emission 538nm with maximum intensity 91289.2 and 71880,7 cps for samples 3:1 and 4:1, respectively. Sample 3:1 with the highest percentage of rutile phase favored photoluminescence. (author)

  20. Hydrothermal synthesis and enhanced photocatalytic activity of mixed-phase TiO2 powders with controllable anatase/rutile ratio

    Science.gov (United States)

    Wang, Qi; Qiao, Zhi; Jiang, Peng; Kuang, Jianlei; Liu, Wenxiu; Cao, Wenbin

    2018-03-01

    In this study, mixed-phase TiO2 powders were novelly synthesized via a facile and mild hydrothermal method without any post-heat treatment. TiOSO4 and peroxide titanic acid (PTA) were used as inorganic titanium sources, while no special solvent or additive were introduced. The XRD and TEM results showed the mixed-phase TiO2 powders were composed of anatase and rutile phases, and the PTA sol played an important role on forming the rutile nucleus. The proportion of rutile in the mixed-phase TiO2 could be easily controlled in the range of 0%-70.5% by changing the amount of PTA sol used in the synthesis process. The UV-Visible absorption spectra indicated the prepared mixed-phase TiO2 showed enhanced visible light absorption with the increase of rutile ratio. The photodegradation experiments revealed the mixed-phase TiO2 exhibited the best photocatalytic activity at the rutile ratio of 41.5%, while a higher or lower rutile ratio both resulted in the decrease of photocatalytic activity.

  1. Systematic identification method for data analysis and phase equilibria modelling for lipids systems

    DEFF Research Database (Denmark)

    Perederic, Olivia A.; Cunico, Larissa P.; Kalakul, Sawitree

    2018-01-01

    Industrial use of lipids has been increasing as a consequence of increased developments related to biobased economies. In addition to applications in food-products, lipids are used by many industrial sectors, for example, biodiesel, edible oil, health, and personal care. Phase equilibria...

  2. Phase equilibria, phases and compounds in the Ti-C system

    International Nuclear Information System (INIS)

    Gusev, Aleksandr I

    2002-01-01

    The results of experimental and theoretical investigations of the phase equilibria in the titanium-carbon system are generalised. The generalised thermodynamic characteristics of disordered titanium carbide TiC y , are reported. Peculiarities of the crystal structures of all the known and hypothetical compounds of titanium with carbon are considered in detail. The X-ray diffraction patterns which allow identification of all these compounds are presented. The phase diagrams of the Ti-C system constructed with allowance for atomic ordering of non-stoichio metric carbide, TiC y , and for the existence of the molecular cluster-like compounds Ti 8 C 12 and Ti 13 C 22 (TiC 2 ) are discussed. The bibliography includes 142 references.

  3. Phase equilibria, phases and compounds in the Ti-C system

    International Nuclear Information System (INIS)

    Gusev, A.I.

    2002-01-01

    The results of experimental and theoretical investigations related to the phase equilibria in the titanium-carbon system are generalized. The generalized thermodynamic characteristics of the disordered titanium carbide TiC y are given. The crystal structure of all the discovered and hypothetical compounds of titanium with carbon are considered in detail. The x-ray diffraction patterns which allow one to identify all these compounds are given. The phase diagrams of the Ti-C system constructed with allowance for atomic ordering of non-stoichiometric TiC y carbide and for the existence of the compounds Ti 8 C 12 and Ti 13 C 22 (TiC 2 ) of the molecule cluster type are discussed [ru

  4. Experimental investigation of phase equilibria in the Ni-Nb-V ternary system

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xingjun; Yang, Shuiyuan; Wang, Cuiping [Xiamen Univ. (China). Dept. of Materials Science and Engineering; Xiamen Univ. (China). Fujian Provincial Key Lab. of Materials Genome; Zhang, Xianjie; Jiang, Hengxing; Shi, Zhan [Xiamen Univ. (China). Dept. of Materials Science and Engineering

    2017-09-15

    The phase equilibria of the Ni-Nb-V ternary system at 1000 C and 1200 C were established using electron probe microanalysis, X-ray diffraction and differential scanning calorimetry. The results of the investigation revealed that: (1) The Nb solubility in (Ni) and σ{sup '} phases was less than 10 at.%; (2) A ternary compound τ (NiNbV) was confirmed, in which V had a large solubility; (3) A new liquid region was evident at 1200 C, but was absent at 1000 C; (4) The lattice constants of Ni{sub 3}Nb and Ni{sub 6}Nb{sub 7} phase decreased with increase in V content in the Ni{sub 3}Nb and Ni{sub 6}Nb{sub 7}. The phase equilibria of the Ni-Nb-V ternary system will contribute to its thermodynamic assessment.

  5. Experimental investigation of phase equilibria in the Zr-Cu-Ni ternary system

    International Nuclear Information System (INIS)

    Yang, Mujin; Wang, Cuiping; Yang, Shuiyuan; Shi, Zhan; Han, Jiajia; Liu, Xingjun

    2017-01-01

    The phase equilibria in the Zr-Cu-Ni ternary system are investigated combined with X-ray diffraction, electron probe micro-analysis and differential scanning calorimetry. Two isothermal sections of the Zr-Cu-Ni ternary system at 1 000 C and 1 100 C are experimentally established. Most of the binary intermetallic compounds, e.g. Zr 7 Ni 10 , ZrNi, ZrNi 5 , Zr 14 Cu 51 , and Zr 2 Cu 9 , show a remarkable ternary solubility. A new ternary compound named τ 3 (Zr 31.1-30.7 . Cu 28.5-40.3 Ni 40.4-29.0 ) is detected at 1 000 C and dissolved at 1 020 C because the nearby large liquid phase field further expands. The newly determined phase equilibria will provide important information for both thermodynamic assessment and alloy design of Zr-based metallic glass.

  6. Thermodynamic calculations in the system CH4-H2O and methane hydrate phase equilibria

    Science.gov (United States)

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

    2006-01-01

    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.

  7. High-pressure phase equilibria in the (carbon dioxide + 1-hexanol) system

    International Nuclear Information System (INIS)

    Secuianu, Catinca; Feroiu, Viorel; Geana, Dan

    2010-01-01

    (Vapour + liquid) equilibria (VLE) and (vapour + liquid + liquid) equilibria (VLLE) data for the (carbon dioxide + 1-hexanol) system were measured at (293.15, 303.15, 313.15, 333.15, and 353.15) K. Phase behaviour measurements were made in a high-pressure visual cell with variable volume, based on the static-analytic method. The pressure range under investigation was between (0.6 and 14.49) MPa. The Soave-Redlich-Kwong (SRK) equation of state (EOS) with classical van der Waals mixing rules (two-parameters conventional mixing rule, 2PCMR), was used in a semi-predictive approach, in order to represent the complex phase behaviour (critical curve, LLV line, isothermal VLE, LLE, and VLLE) of the system. The topology of phase behaviour is reasonably well predicted.

  8. Phase equilibria in Ca–Co–O system

    Czech Academy of Sciences Publication Activity Database

    Sedmidubský, D.; Jakeš, V.; Jankovský, O.; Leitner, J.; Šofer, Z.; Hejtmánek, Jiří

    2012-01-01

    Roč. 194, OCT (2012), s. 199-205 ISSN 0022-4596 R&D Projects: GA ČR GA203/09/1036 Institutional research plan: CEZ:AV0Z10100521 Keywords : Ca–Co–O system , Misfit cobaltites, Thermodynamic data, Phase diagrams * misfit cobaltites * thermodynamic data * phase diagrams Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.040, year: 2012

  9. Generalized thermodynamics of phase equilibria in scalar active matter

    Science.gov (United States)

    Solon, Alexandre P.; Stenhammar, Joakim; Cates, Michael E.; Kafri, Yariv; Tailleur, Julien

    2018-02-01

    Motility-induced phase separation (MIPS) arises generically in fluids of self-propelled particles when interactions lead to a kinetic slowdown at high densities. Starting from a continuum description of scalar active matter akin to a generalized Cahn-Hilliard equation, we give a general prescription for the mean densities of coexisting phases in flux-free steady states that amounts, at a hydrodynamics scale, to extremizing an effective free energy. We illustrate our approach on two well-known models: self-propelled particles interacting either through a density-dependent propulsion speed or via direct pairwise forces. Our theory accounts quantitatively for their phase diagrams, providing a unified description of MIPS.

  10. Ab initio study of phase equilibria in TiCx

    DEFF Research Database (Denmark)

    Korzhavyi, P.A.; Pourovskii, L.V.; Hugosson, H.W.

    2002-01-01

    The phase diagram for the vacancy-ordered structures in the substoichiometric TiCx (x = 0.5-1.0) has been established from Monte Carlo simulations with the long-range pair and multisite effective interactions obtained from ab initio calculations. Three ordered superstructures of vacancies (Ti2C, Ti...

  11. Revelation of rutile phase by Raman scattering for enhanced photoelectrochemical performance of hydrothermally-grown anatase TiO2 film

    Science.gov (United States)

    Cho, Hsun-Wei; Liao, Kuo-Lun; Yang, Jih-Sheng; Wu, Jih-Jen

    2018-05-01

    Photoelectrochemical (PEC) performances of the anatase TiO2 films hydrothermally grown on the seeded fluorine-doped tin oxide (FTO) substrates are examined in this work. Structural characterizations of the TiO2 films were conducted using Raman scattering spectroscopy. Although there is no obvious rutile peak appearing, an asymmetrical peak centered at ∼399 cm-1 was observed in the Raman spectra of the TiO2 films deposited either on the low-temperature-formed seed layers or with low concentrations of Ti precursor. The asymmetrical Raman shift can be deconvoluted into the B1g mode of anatase and Eg mode of rutile TiO2 peaks centered at ∼399 cm-1 and ∼447 cm-1, respectively. Therefore, a minute quantity of rutile phase was inspected in the anatase film using Raman scattering spectroscopy. With the same light harvesting ability, we found that the PEC performance of the anatase TiO2 film was significantly enhanced as the minute quantity of rutile phase existing in the film. It is ascribed to the formation of the anatase/rutile heterojunction which is beneficial to the charge separation in the photoanode.

  12. High-pressure anatectic paragneisses from the Namche Barwa, Eastern Himalayan Syntaxis: Textural evidence for partial melting, phase equilibria modeling and tectonic implications

    Science.gov (United States)

    Guilmette, C.; Indares, A.; Hébert, R.

    2011-05-01

    Rare kyanite-bearing anatectic paragneisses are found as boudins within sillimanite-bearing paragneisses of the core of the Namche Barwa Antiform, Tibet. In the present study, we document an occurrence from the NW side of the Yarlung Zangbo River. These rocks mainly consist of the assemblage garnet + K-feldspar + kyanite ± biotite + quartz + rutile ± plagioclase with kyanite locally pseudomorphed by sillimanite. The documented textures are consistent with the rocks having undergone biotite-dehydration melting in the kyanite stability field, under high-P granulite facies conditions, and having experienced melt extraction. However textures related to melt crystallization are ubiquitous both in polymineralic inclusions in garnet and in the matrix, suggesting that a melt fraction had remained in these rocks. Phase equilibria modelling was undertaken in the NCKFMASTHO system with THERMOCALC. P-T pseudosections built with the bulk compositions of one aluminous and one sub-aluminous paragneiss samples predict a biotite-kyanite-garnet-quartz-plagioclase-K-feldspar-liquid-rutile ± ilmenite field, in which biotite-dehydration melting occurs, located in the P-T range of ~ 800-875 °C and ~ 10-17 kbar. In addition, the topologies of these pseudosections are consistent with substantial melt loss during prograde metamorphism. A second set of P-T pseudosections with melt-reintegrated model bulk compositions were thus constructed to evaluate the effect of melt loss. The integration of textural information, precise mineral modes, mineral chemistry, and phase equilibria modelling allowed to constrain a P-T path where the rocks are buried to lower crustal depths at peak P-T conditions higher than 14 kbar and 825 °C, possibly in the order of 15-16 kbar and 850 °C, followed by decompression and cooling to P-T conditions of around 9 kbar and 810 °C, under which the remaining melt was solidified. The implications for granite production at the NBA and for Himalayan tectonic models

  13. Thermal analysis and prediction of phase equilibria in ternary Pb-Zn-Ag system

    Directory of Open Access Journals (Sweden)

    Živković D.

    2011-01-01

    Full Text Available Ternary Pb-Zn-Ag system is typical for some physicochemical processes going on in refining phase in the extractive metallurgy of lead. Therefore, investigation of mentioned system is important from both theoretical and practical research of the phenomena occurring during the lead desilverizing process. The results of experimental investigation using differential thermal analysis (DTA and thermodynamic calculation of phase equilibria in Pb-Zn-Ag system according to CALPHAD method, in the sections with Zn:Ag mass ratio equal to 90:10, 70:30 and 50:50, are presented in this paper.

  14. Corium phase equilibria based on MASCA, METCOR and CORPHAD results

    Energy Technology Data Exchange (ETDEWEB)

    Bechta, S.V.; Granovsky, V.S.; Khabensky, V.B. [Alexandrov Research Institute of Technologies (NITI), Sosnovy Bor (Russian Federation); Gusarov, V.V.; Almiashev, V.I.; Mezentseva, L.P. [Grebenshikov Institute of Silicate Chemistry, Russian Academy of Sciences (ISCh RAS), St. Petersburg (Russian Federation); Krushinov, E.V.; Kotova, S.Yu.; Kosarevsky, R.A. [Alexandrov Research Institute of Technologies (NITI), Sosnovy Bor (Russian Federation); Barrachin, M. [Institut de Radioprotection et Surete Nucleaire IRSN/DPAM, St Paul lez Durance (France); Bottomley, D. [EUROPAISCHE KOMMISSION, Joint Research Centre Institut fuer Transurane (ITU), Karlsruhe (Germany); Fichot, F. [Institut de Radioprotection et Surete Nucleaire IRSN/DPAM, St Paul lez Durance (France); Fischer, M. [AREVA NP GmbH, Erlangen (Germany)], E-mail: Manfred.Fischer@areva.com

    2008-10-15

    Experimental data on component partitioning between suboxidized corium melt and steel in the in-vessel melt retention (IVR) conditions are compared. The data are produced within the OECD MASCA program and the ISTC CORPHAD project under close-to-isothermal conditions and in the ISTC METCOR project under thermal gradient conditions. Chemical equilibrium in the U-Zr-Fe(Cr,Ni,...)-O system is reached in all experiments. In MASCA tests the molten pool formed under inert atmosphere has two immiscible liquids, oxygen-enriched (oxidic) and oxygen-depleted (metallic), resulting of the miscibility gap of the mentioned system. Sub-system data of the U-Zr-Fe(Cr,Ni,...)-O phase diagram investigated within the ISTC CORPHAD project are interpreted in relation with the MASCA results. In METCOR tests the equilibrium is established between oxidic liquid and mushy metallic part of the system. Results of comparison are discussed and the implications for IVR noted.

  15. Thermodynamic investigation of the phase equilibrium boundary between TiO2 rutile and its α-PbO2-type high-pressure polymorph

    Science.gov (United States)

    Kojitani, Hiroshi; Yamazaki, Monami; Kojima, Meiko; Inaguma, Yoshiyuki; Mori, Daisuke; Akaogi, Masaki

    2018-06-01

    Heat capacity (C P) of rutile and α-PbO2 type TiO2 (TiO2-II) were measured by the differential scanning calorimetry and thermal relaxation method. Using the results, standard entropies at 1 atm and 298.15 K of rutile and TiO2-II were determined to be 50.04(4) and 46.54(2) J/mol K, respectively. Furthermore, thermal expansivity (α) determined by high-temperature X-ray diffraction measurement and mode Grüneisen parameters obtained by high-pressure Raman spectroscopy suggested the thermal Grüneisen parameter (γ th) for TiO2-II of 1.7(1). By applying the obtained low-temperature C P and γ th, the measured C P and α data of TiO2-II were extrapolated to higher temperature region using a lattice vibrational model calculation, as well as rutile. Internally consistent thermodynamic data sets of both rutile and TiO2-II assessed in this study were used to thermodynamically calculate the rutile‒TiO2-II phase equilibrium boundary. The most plausible boundary was obtained to be P (GPa) = 0.0074T (K) - 1.7. Our boundary suggests that the crystal growth of TiO2-II observed below 5.5 GPa and 900 K in previous studies advanced in its stability field. The phase boundary calculation also suggested small, exothermic phase transition enthalpy from rutile to TiO2-II at 1 atm and 298.15 K of - 0.5 to - 1.1 kJ/mol. This implies that the thermodynamic stability of rutile at 1 atm above room temperature is due to larger contribution of entropy term.

  16. The prediction and representation of phase equilibria and physicochemical properties in complex coal ash slag systems

    Energy Technology Data Exchange (ETDEWEB)

    E. Jak; A. Kondratiev; S. Christie; P.C. Hayes [Centre for Coal in Sustainable Development (CCSD), Brisbane (Australia)

    2003-07-01

    A range of problems in coal utilisation technologies, including ash slag flow in slagging gasifiers, deposit formation, slagging, fouling, fusibility tests, fluxing, blending etc, are related to the melting behaviour of the mineral matter in the coal. To assist with solving these practical issues i) thermodynamic modelling of phase equilibria, and ii) viscosity modelling studies are being undertaken at the Pyrometallurgy Research Centre (The University of Queensland, Australia) with support from the Collaborative Research Centre for Coal in Sustainable Development (CCSD). The thermodynamic modelling has been carried out using the computer system FactSage, which is used for the calculation of multi-phase slag / solid / gas / matte / alloy / salt equilibria in multi-component systems of industrial interest. A modified quasi-chemical solution model is used for the liquid slag phase. New model optimisations have been carried out, which have significantly improved the accuracy of the thermodynamic models for coal combustion processes. Viscosity modelling, using a modified Urbain formalism, is carried out in conjunction with FactSage calculations to predict the viscosities of fully liquid as well as heterogeneous, partly crystallised slags. Custom designed software packages are developed using these fundamental models for wider use by industrial researchers and engineers, and for incorporation as process control modules. The new custom-designed computer software package can be used to produce limiting operability diagrams for slag systems. These diagrams are used to describe phase equilibria and physico-chemical properties in complex slag systems. The approach is illustrated with calculations on the system SiO{sub 2}-Al{sub 2}O{sub 3}-FeO-Fe{sub 2}O{sub 3}-CaO at metallic iron saturation, slags produced in coal slagging gasifiers. 28 refs., 7 figs., 1 tab.

  17. Thermodynamic calculation of phase equilibria of the U-Ga and U-W systems

    International Nuclear Information System (INIS)

    Wang, J.; Liu, X.J.; Wang, C.P.

    2008-01-01

    The thermodynamic assessments of the U-Ga and U-W systems have been carried out by using the CALPHAD (calculation of phase diagrams) method using experimental data including thermodynamic properties and phase equilibria. Gibbs free energies of the solution phases were described by the subregular solution models with the Redlich-Kister equation, and those of the intermetallic compounds were described by the sublattice models. A consistent set of thermodynamic parameters has been derived for the Gibbs free energy of each phase in the U-Ga and U-W binary systems, respectively. The calculated phase diagrams and thermodynamic properties in the U-Ga and U-W systems are in good agreement with experimental data

  18. Prediction of phase equilibria in the In–Sb–Pb system

    Directory of Open Access Journals (Sweden)

    DUSKO MINIC

    2008-03-01

    Full Text Available Binary thermodynamic data, successfully used for phase diagram calculations of the binary systems In–Sb, Pb–Sb and In–Pb, were used for the prediction of the phase equilibria in the ternary In–Sb–Pb system. The predicted equilibrium phase diagram of the vertical Pb–InSb section was compared with the results of differential thermal analysis DTA and optical microscopy. The calculated phase diagram of the isothermal section at 300 °C was compared with the experimentally (SEM, EDX determined composition of phases in the chosen alloys after annealing. Very good agreement between the binary-based thermodynamic prediction and the experimental data was found in all cases. The calculated liquidus projection of the ternary In–Sb–Pb system is also presented.

  19. Experimental investigation of phase equilibria in the Nb-Si-Ta ternary system

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jian; Wang, Cuiping; Yao, Jun; Yang, Shuiyuan; Zhan Shi; Liu, Xingjun [Xiamen Univ. (China). Dept. of Materials Science and Engineering; Xiamen Univ. (China). Fujian Provincial Key Laboratory of Materials Genome; Kang, Yongwang [Beijing Institute of Aeronautical Materials (China). Science and Technology on Advanced High Temperature Structural Materials Lab.

    2016-12-15

    The phase equilibria in the Nb-Si-Ta ternary system at 1 373 K, 1 473 K and 1 573 K were investigated by means of back-scattered electron imaging, electron probe microanalysis and X-ray diffraction. The isothermal sections at 1 373 K, 1 473 K and 1 573 K consist of two three-phase regions and seven two-phase regions, without any ternary compounds. The compounds of NbSi{sub 2} and TaSi{sub 2}, αNb{sub 5}Si{sub 3} and αTa{sub 5}Si{sub 3} form continuous solid solutions, respectively. The solubilities of Nb in Ta{sub 3}Si and Ta{sub 2}Si phases are extremely large, whereas the solubility of Si in the β(Nb, Ta) phase is relatively small.

  20. Experimental investigation of phase equilibria in the Co-W-V ternary system

    International Nuclear Information System (INIS)

    Liu Xingjun; Zhu Yihong; Yu Yan; Wang Cuiping

    2011-01-01

    Highlights: → Three isothermal sections of the Co-W-V ternary system at 1100 deg. C, 1200 deg. C and 1300 deg. C were determined. → No ternary compound was found in the Co-W-V ternary system. → A stable liquid miscibility gap is newly discovered in the Co-W-V ternary system. → This work is of great essence to establish the thermodynamic database for the Co-based alloys. - Abstract: The phase equilibria in the Co-W-V ternary system were experimentally investigated by optical microscopy (OM), electron probe microanalysis (EPMA) and X-ray diffraction (XRD) on the equilibrated alloys. Three isothermal sections of the Co-W-V ternary system at 1100 deg. C, 1200 deg. C and 1300 deg. C were determined, and no ternary compound was found in this system. In addition, a novel phenomena induced by the liquid phase separation in the Co-W-V alloys was firstly discovered, suggesting that a stable liquid miscibility gap exists in the Co-W-V ternary system. The newly determined phase equilibria and firstly discovered phase separation phenomena in the Co-W-V system will provide important information for the development of Co-W based alloys.

  1. Phases, phase equilibria, and phase rules in low-dimensional systems

    International Nuclear Information System (INIS)

    Frolov, T.; Mishin, Y.

    2015-01-01

    We present a unified approach to thermodynamic description of one, two, and three dimensional phases and phase transformations among them. The approach is based on a rigorous definition of a phase applicable to thermodynamic systems of any dimensionality. Within this approach, the same thermodynamic formalism can be applied for the description of phase transformations in bulk systems, interfaces, and line defects separating interface phases. For both lines and interfaces, we rigorously derive an adsorption equation, the phase coexistence equations, and other thermodynamic relations expressed in terms of generalized line and interface excess quantities. As a generalization of the Gibbs phase rule for bulk phases, we derive phase rules for lines and interfaces and predict the maximum number of phases than may coexist in systems of the respective dimensionality

  2. Solid-liquid phase equilibria of Fe-Cr-Al alloys and spinels

    Science.gov (United States)

    McMurray, J. W.; Hu, R.; Ushakov, S. V.; Shin, D.; Pint, B. A.; Terrani, K. A.; Navrotsky, A.

    2017-08-01

    Ferritic FeCrAl alloys are candidate accident tolerant cladding materials. There is a paucity of data concerning the melting behavior for FeCrAl and its oxides. Analysis tools have therefore had to utilize assumptions for simulations using FeCrAl cladding. The focus of this study is to examine in some detail the solid-liquid phase equilibria of FeCrAl alloys and spinels with the aim of improving the accuracy of severe accident scenario computational studies.

  3. Phase equilibria of didecyldimethylammonium nitrate ionic liquid with water and organic solvents

    International Nuclear Information System (INIS)

    Domanska, Urszula; Lugowska, Katarzyna; Pernak, Juliusz

    2007-01-01

    The phase diagrams for binary mixtures of an ammonium ionic liquid, didecyldimethylammonium nitrate, [DDA][NO 3 ], with: alcohols (propan-1-ol, butan-1-ol, octan-1-ol, and decan-1-ol): hydrocarbons (toluene, propylbenzene, hexane, and hexadecane) and with water were determined in our laboratory. The phase equilibria were measured by a dynamic method from T 220 K to either the melting point of the ionic liquid, or to the boiling point of the solvent. A simple liquidus curve in a eutectic system was observed for [DDA][NO 3 ] with: alcohols (propan-1-ol, butan-1-ol, and octan-1-ol); aromatic hydrocarbons (toluene and propylbenzene) and with water. (Solid + liquid) equilibria with immiscibility in the liquid phase were detected with the aliphatic hydrocarbons heptane and hexadecane and with decan-1-ol. (Liquid + liquid) equilibria for the system [DDA][NO 3 ] with hexadecane was observed for the whole mole fraction range of the ionic liquid. The observation of the upper critical solution temperature in binary mixtures of ([DDA][NO 3 ] + decan-1-ol, heptane, or hexadecane) was limited by the boiling temperature of the solvent. Characterisation and purity of the compounds were determined by elemental analysis, water content (Fisher method) and differential scanning microcalorimetry (d.s.c.) analysis. The d.s.c. method of analysis was used to determine melting temperatures and enthalpies of fusion. The thermal stability of the ionic liquid was resolved by the thermogravimetric technique-differential thermal analysis (TG-DTA) technique over a wide temperature range from (200 to 780) K. The thermal decomposition temperature of 50% of the sample was greater than 500 K. The (solid + liquid) phase equilibria, curves were correlated by means of different G Ex models utilizing parameters derived from the (solid + liquid) equilibrium. The root-mean-square deviations of the solubility temperatures for all calculated data are dependent upon the particular system and the particular

  4. Computed phase equilibria for burnable neutron absorbing materials for advanced pressurized heavy water reactors

    Energy Technology Data Exchange (ETDEWEB)

    Corcoran, E.C. [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, P.O. Box 17000, St. Forces, Kingston, Ont., K7K 7B4 (Canada)], E-mail: emily.corcoran@rmc.ca; Lewis, B.J.; Thompson, W.T. [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, P.O. Box 17000, St. Forces, Kingston, Ont., K7K 7B4 (Canada); Hood, J. [Atomic Energy of Canada Ltd., Sheridan Park, 2251 Speakman Drive, Mississauga, Ont., L5K 1B2 (Canada); Akbari, F.; He, Z. [Atomic Energy of Canada Ltd., Chalk River Laboratories, Chalk River, Ont., K0J 1J0 (Canada); Reid, P. [Atomic Energy of Canada Ltd., Sheridan Park, 2251 Speakman Drive, Mississauga, Ont., L5K 1B2 (Canada)

    2009-03-31

    Burnable neutron absorbing materials are expected to be an integral part of the new fuel design for the Advanced CANDU [CANDU is as a registered trademark of Atomic Energy of Canada Limited.] Reactor. The neutron absorbing material is composed of gadolinia and dysprosia dissolved in an inert cubic-fluorite yttria-stabilized zirconia matrix. A thermodynamic model based on Gibbs energy minimization has been created to provide estimated phase equilibria as a function of composition and temperature. This work includes some supporting experimental studies involving X-ray diffraction.

  5. Phase equilibria in Dy-Cu-Al system at 500 deg C

    International Nuclear Information System (INIS)

    Kuz'ma, Yu.B.; Milyan, V.V.

    1989-01-01

    Using the methods of X-ray diffraction analysis a diagram of phase equilibria in Dy-Cu-Al system at 500 deg C is plotted. Boundaries of solid solutions on the basis of DyCu 2 , DyCu and DyAl 2 compounds are determined and homogeneity regions of ternary compounds Dy 2 (Cu, Al) 7 and Dy(CuAl) 5 are ascertained. Compounds DyCuAl 3 , Dy 4 Cu 4 Al 11 and Dy 5 Cu 6 Al 9 have been detected for the first time

  6. Phase equilibria and critical phenomena in the cesium nitrate-water-diethylamine ternary system

    International Nuclear Information System (INIS)

    Il'in, K.K.; Kurskij, V.F.; Cherkasov, D.G.

    2008-01-01

    Phase equilibria and critical events in ternary cesium nitrate-water-diethylamine system, where border binary liquid system is characterized by aliquation with lower critical temperature of solution (LCTS), have been investigated by visual-polythermal method in the 60-150 Deg C range. Interaction of cesium nitrate in the water-diethylamine system leads to lowering of its LCTS from 146.1 to 69.3 Deg C and decrease of mutual solubility. Distribution ratios of diethylamine between water and organic phases of monotectic equilibrium are calculated at different temperatures. Diethylamine salting out from aqueous solutions by cesium nitrates becomes stronger with rising temperature. Plotted isotherms of phase confirms generalized scheme of topological transformations of ternary systems phase diagrams: salt-binary solvent with salting out

  7. Experimental study of the Cu-Al-Sn phase equilibria, close to the copper zone

    Directory of Open Access Journals (Sweden)

    Soares D.F.

    2017-01-01

    Full Text Available The ternary Cu-Al-Sn phase diagram is the base for several important types of alloys, with relevant industrial interest and applications. The knowledge of the melting/solidification alloys characteristics are determinant for their preparation and properties control. However, there is a lack of experimental information on the ternary phase diagram, at high temperature. In this work, several alloys, with high copper content and additions of Al, up to 10%, and Sn, up to 14% (in wt%, were studied by thermal analysis and by isothermal phase equilibria determination. The alloys liquidus and solidus lines and the binary α + β phase field, at 800°C, are presented for the studied range of compositions.

  8. UV and visible light photocatalytic activity of Au/TiO2 nanoforests with Anatase/Rutile phase junctions and controlled Au locations.

    Science.gov (United States)

    Yu, Yang; Wen, Wei; Qian, Xin-Yue; Liu, Jia-Bin; Wu, Jin-Ming

    2017-01-24

    To magnify anatase/rutile phase junction effects through appropriate Au decorations, a facile solution-based approach was developed to synthesize Au/TiO 2 nanoforests with controlled Au locations. The nanoforests cons®isted of anatase nanowires surrounded by radially grown rutile branches, on which Au nanoparticles were deposited with preferred locations controlled by simply altering the order of the fabrication step. The Au-decoration increased the photocatalytic activity under the illumination of either UV or visible light, because of the beneficial effects of either electron trapping or localized surface plasmon resonance (LSPR). Gold nanoparticles located preferably at the interface of anatase/rutile led to a further enhanced photocatalytic activity. The appropriate distributions of Au nanoparticles magnify the beneficial effects arising from the anatase/rutile phase junctions when illuminated by UV light. Under the visible light illumination, the LSPR effect followed by the consecutive electron transfer explains the enhanced photocatalysis. This study provides a facile route to control locations of gold nanoparticles in one-dimensional nanostructured arrays of multiple-phases semiconductors for achieving a further increased photocatalytic activity.

  9. Experimental investigation of phase equilibria in the Zr-Cu-Ni ternary system

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Mujin; Wang, Cuiping; Yang, Shuiyuan; Shi, Zhan; Han, Jiajia; Liu, Xingjun [Xiamen Univ. (China). College of Materials and Fujian Provincial Key Lab. of Materials Genome

    2017-08-15

    The phase equilibria in the Zr-Cu-Ni ternary system are investigated combined with X-ray diffraction, electron probe micro-analysis and differential scanning calorimetry. Two isothermal sections of the Zr-Cu-Ni ternary system at 1 000 C and 1 100 C are experimentally established. Most of the binary intermetallic compounds, e.g. Zr{sub 7}Ni{sub 10}, ZrNi, ZrNi{sub 5}, Zr{sub 14}Cu{sub 51}, and Zr{sub 2}Cu{sub 9}, show a remarkable ternary solubility. A new ternary compound named τ{sub 3} (Zr{sub 31.1-30.7} . Cu{sub 28.5-40.3}Ni{sub 40.4-29.0}) is detected at 1 000 C and dissolved at 1 020 C because the nearby large liquid phase field further expands. The newly determined phase equilibria will provide important information for both thermodynamic assessment and alloy design of Zr-based metallic glass.

  10. Evaluation of Thermodynamic Models for Predicting Phase Equilibria of CO2 + Impurity Binary Mixture

    Science.gov (United States)

    Shin, Byeong Soo; Rho, Won Gu; You, Seong-Sik; Kang, Jeong Won; Lee, Chul Soo

    2018-03-01

    For the design and operation of CO2 capture and storage (CCS) processes, equation of state (EoS) models are used for phase equilibrium calculations. Reliability of an EoS model plays a crucial role, and many variations of EoS models have been reported and continue to be published. The prediction of phase equilibria for CO2 mixtures containing SO2, N2, NO, H2, O2, CH4, H2S, Ar, and H2O is important for CO2 transportation because the captured gas normally contains small amounts of impurities even though it is purified in advance. For the design of pipelines in deep sea or arctic conditions, flow assurance and safety are considered priority issues, and highly reliable calculations are required. In this work, predictive Soave-Redlich-Kwong, cubic plus association, Groupe Européen de Recherches Gazières (GERG-2008), perturbed-chain statistical associating fluid theory, and non-random lattice fluids hydrogen bond EoS models were compared regarding performance in calculating phase equilibria of CO2-impurity binary mixtures and with the collected literature data. No single EoS could cover the entire range of systems considered in this study. Weaknesses and strong points of each EoS model were analyzed, and recommendations are given as guidelines for safe design and operation of CCS processes.

  11. Sn-In-Ag phase equilibria and Sn-In-(Ag)/Ag interfacial reactions

    International Nuclear Information System (INIS)

    Chen Sinnwen; Lee Wanyu; Hsu Chiaming; Yang Chingfeng; Hsu Hsinyun; Wu Hsinjay

    2011-01-01

    Research highlights: → Thermodynamic models of Sn-In and Sn-In-Ag are developed using the CALPHAD approach. → Reaction layer in the Sn-In-(Ag)/Ag couples at 100 deg. C is thinner than those at 25 deg. C, 50 deg. C, and 75 deg. C. → Reactions in the Sn-20 wt%In-2.8 wt%Ag/Ag couples are faster than those in the Sn-20 wt%In/Ag couples. - Abstract: Experimental verifications of the Sn-In and Sn-In-Ag phase equilibria have been conducted. The experimental measurements of phase equilibria and thermodynamic properties are used for thermodynamic modeling by the CALPHAD approach. The calculated results are in good agreement with experimental results. Interfacial reactions in the Sn-In-(Ag)/Ag couples have been examined. Both Ag 2 In and AgIn 2 phases are formed in the Sn-51.0 wt%In/Ag couples reacted at 100 and 150 deg. C, and only the Ag 2 In phase is formed when reacted at 25, 50 and 75 deg. C. Due to the different growth rates of different reaction phases, the reaction layer at 100 deg. C is thinner than those at 25 deg. C, 50 deg. C, and 75 deg. C. In the Sn-20.0 wt%In/Ag couples, the ζ phase is formed at 250 deg. C and ζ/AgIn 2 phases are formed at 125 deg. C. Compared with the Sn-20 wt%In/Ag couples, faster interfacial reactions are observed in the Sn-20.0 wt%In-2.8 wt%Ag/Ag couples, and minor Ag addition to Sn-20 wt%In solder increases the growth rates of the reaction phases.

  12. Another dimension to metamorphic phase equilibria: the power of interactive movies for understanding complex phase diagram sections

    Science.gov (United States)

    Moulas, E.; Caddick, M. J.; Tisato, N.; Burg, J.-P.

    2012-04-01

    The investigation of metamorphic phase equilibria, using software packages that perform thermodynamic calculations, involves a series of important assumptions whose validity can often be questioned but are difficult to test. For example, potential influences of deformation on phase relations, and modification of effective reactant composition (X) at successive stages of equilibrium may both introduce significant uncertainty into phase diagram calculations. This is generally difficult to model with currently available techniques, and is typically not well quantified. We present here a method to investigate such phenomena along pre-defined Pressure-Temperature (P-T) paths, calculating local equilibrium via Gibbs energy minimization. An automated strategy to investigate complex changes in the effective equilibration composition has been developed. This demonstrates the consequences of specified X modification and, more importantly, permits automated calculation of X changes that are likely along the requested path if considering several specified processes. Here we describe calculations considering two such processes and show an additional example of a metamorphic texture that is difficult to model with current techniques. Firstly, we explore the assumption that although water saturation and bulk-rock equilibrium are generally considered to be valid assumptions in the calculation of phase equilibria, the saturation of thermodynamic components ignores mechanical effects that the fluid/melt phase can impose on the rock, which in turn can modify the effective equilibrium composition. Secondly, we examine how mass fractionation caused by porphyroblast growth at low temperatures or progressive melt extraction at high temperatures successively modifies X out of the plane of the initial diagram, complicating the process of determining best-fit P-T paths for natural samples. In particular, retrograde processes are poorly modeled without careful consideration of prograde

  13. Ternary systems Sr-{Ni,Cu}-Si: Phase equilibria and crystal structure of ternary phases

    International Nuclear Information System (INIS)

    Nasir, Navida; Melnychenko-Koblyuk, Nataliya; Grytsiv, Andriy; Rogl, Peter; Giester, Gerald; Wosik, Jaroslaw; Nauer, Gerhard E.

    2010-01-01

    Phase relations were established in the Sr-poor part of the ternary systems Sr-Ni-Si (900 deg. C) and Sr-Cu-Si (800 deg. C) by light optical microscopy, electron probe microanalysis and X-ray diffraction on as cast and annealed alloys. Two new ternary compounds SrNiSi 3 (BaNiSn 3 -type) and SrNi 9-x Si 4+x (own-type) were found in the Sr-Ni-Si system along with previously reported Sr(Ni x Si 1-x ) 2 (AlB 2 -type). The crystal structure of SrNi 9-x Si 4+x (own-type, x=2.7, a=0.78998(3), c=1.1337(2) nm; space group P4/nbm) was determined from X-ray single crystal counter to be a low symmetry derivative of the cubic, parent NaZn 13 -type. At higher Si-content X-ray Rietveld refinements reveal the formation of a vacant site (□) corresponding to a formula SrNi 5.5 Si 6.5 □ 1.0 . Phase equilibria in the Sr-Cu-Si system are characterized by the compounds SrCu 2-x Si 2+x (ThCr 2 Si 2 -type), Sr(Cu x Si 1-x ) 2 (AlB 2 -type), SrCu 9-x Si 4+x (0≤x≤1.0; CeNi 8.5 Si 4.5 -type) and SrCu 13-x Si x (4≤x≤1.8; NaZn 13 -type). The latter two structure types appear within a continuous solid solution. Neither a type-I nor a type-IX clathrate compound was encountered in the Sr-{Cu,Ni}-Si systems. Structural details are furthermore given for about 14 new ternary compounds from related alloy systems with Ba. - Graphical abstract: The crystal structure of SrNi 9-x Si 4+x (own-type, x=2.7, a=0.78998(3), c=1.1337(2) nm; space group P4/nbm) was determined from X-ray single crystal counter to be a low symmetry derivative of the cubic, parent NaZn 13 -type and is related to CeNi 8.5 Si 4.5 -type.

  14. Phase equilibria for mixtures containing very many components. development and application of continuous thermodynamics for chemical process design

    International Nuclear Information System (INIS)

    Cotterman, R.L.; Bender, R.; Prausnitz, J.M.

    1984-01-01

    For some multicomponent mixtures, where detailed chemical analysis is not feasible, the compositio of the mixture may be described by a continuous distribution function of some convenient macroscopic property suc as normal boiling point or molecular weight. To attain a quantitative description of phase equilibria for such mixtures, this work has developed thermodynamic procedures for continuous systems; that procedure is called continuous thermodynamics. To illustrate, continuous thermodynamics is used to calculate dew points for natural-gas mixtures, solvent loss in a high-pressure absorber, and liquid-liquid phase equilibria in a polymer fractionation process. Continuous thermodynamics provides a rational method for calculating phase equilibria for those mixtures where complete chemical analysis is not available but where composition can be given by some statistical description. While continuous thermodynamics is only the logical limit of the well-known pseudo-component method, it is more efficient than that method because it is less arbitrary and it often requires less computer time

  15. Calculation of ethanol refining by means of extractive distillation with water using simulated data on phase equilibria

    Energy Technology Data Exchange (ETDEWEB)

    Rosak, J; Mertl, I; Huml, M; Wichterle, I

    1980-01-01

    Available data on phase equilibria in binary mixtures pertaining to the system ethanol - water - impurities (7 compounds that represent the main impurities present in raw synthetic or fermentation ethanol) have been gathered for the computer calculation of a column to be used for the refining of ethanol. Missing experimental data on phase equilibria were supplied by simulation using the increment method UNIFAC which predicts phase equilibria on the basis of the chemical structure. All data about the behavior of binary mixtures were correlated by means of the NRTL method and the sets of constants thus obtained were then used in calculations of the column for the refining of ethanol. The results were compared with reality verified on industrial scale.

  16. Phase Equilibria Measurement of Binary Mixture for the Propoxylated Neopentyl Glycol Diacrylate in Supercritical Carbon Dioxide

    International Nuclear Information System (INIS)

    Byun, Hun-Soo

    2016-01-01

    Experimental data are reported on the phase equilibrium of propoxylated neopentyl glycol diacrylate in supercritical carbon dioxide. Phase equilibria data were measured in static method at a temperature of (313.2, 333.2, 353.2, 373.2 and 393.2) K and at pressures up to 27.82 MPa. At a constant pressure, the solubility of propoxylated neopentyl glycol diacrylate for the (carbon dioxide + propoxylated neopentyl glycol diacrylate) system increases as temperature increases. The (carbon dioxide + propoxylated neopentyl glycol diacrylate) system exhibits type-I phase behavior. The experimental result for the (carbon dioxide + propoxylated neopentyl glycol diacrylate) system is correlated with Peng- Robinson equation of state using mixing rule. The critical property of propoxylated neopentyl glycol diacrylate is predicted with Joback and Lyderson method

  17. Phase Equilibria Measurement of Binary Mixture for the Propoxylated Neopentyl Glycol Diacrylate in Supercritical Carbon Dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Byun, Hun-Soo [Chonnam National University, Yeosu (Korea, Republic of)

    2016-04-15

    Experimental data are reported on the phase equilibrium of propoxylated neopentyl glycol diacrylate in supercritical carbon dioxide. Phase equilibria data were measured in static method at a temperature of (313.2, 333.2, 353.2, 373.2 and 393.2) K and at pressures up to 27.82 MPa. At a constant pressure, the solubility of propoxylated neopentyl glycol diacrylate for the (carbon dioxide + propoxylated neopentyl glycol diacrylate) system increases as temperature increases. The (carbon dioxide + propoxylated neopentyl glycol diacrylate) system exhibits type-I phase behavior. The experimental result for the (carbon dioxide + propoxylated neopentyl glycol diacrylate) system is correlated with Peng- Robinson equation of state using mixing rule. The critical property of propoxylated neopentyl glycol diacrylate is predicted with Joback and Lyderson method.

  18. Prediction of phase equilibria and thermal analysis in the Bi-Cu-Pb ternary system

    Energy Technology Data Exchange (ETDEWEB)

    Manasijevic, Dragan [University of Belgrade, Technical Faculty, VJ 12, 19210 Bor (Serbia); Mitovski, Aleksandra, E-mail: amitovski@tf.bor.ac.rs [University of Belgrade, Technical Faculty, VJ 12, 19210 Bor (Serbia); Minic, Dusko [University of Pristina, Faculty of Technical Sciences, 38220 Kosovska Mitrovica (Serbia); Zivkovic, Dragana; Marjanovic, Sasa [University of Belgrade, Technical Faculty, VJ 12, 19210 Bor (Serbia); Todorovic, Radisa [Institute of Mining and Metallurgy, Zeleni Bulevar 35, 19210 Bor (Serbia); Balanovic, Ljubisa [University of Belgrade, Technical Faculty, VJ 12, 19210 Bor (Serbia)

    2010-05-20

    The knowledge about phase diagram of the Bi-Cu-Pb ternary system is of importance in development of copper-lead based bearing materials, soldering and in refining of copper and lead. In this work, the phase diagram of the Bi-Cu-Pb ternary system was calculated by the CALPHAD method using binary thermodynamic parameters included in the COST 531 database. The results include liquidus projection, invariant equilibria and three vertical sections with molar ratio Cu:Pb = 1, Cu:Pb = 1:3 and Bi:Cu = 1. Alloys, with compositions along three predicted vertical sections, were measured using differential scanning calorimetry (DSC). The experimentally determined phase transition temperatures were compared with calculated results and good mutual agreement was noticed.

  19. Prediction of phase equilibria and thermal analysis in the Bi-Cu-Pb ternary system

    International Nuclear Information System (INIS)

    Manasijevic, Dragan; Mitovski, Aleksandra; Minic, Dusko; Zivkovic, Dragana; Marjanovic, Sasa; Todorovic, Radisa; Balanovic, Ljubisa

    2010-01-01

    The knowledge about phase diagram of the Bi-Cu-Pb ternary system is of importance in development of copper-lead based bearing materials, soldering and in refining of copper and lead. In this work, the phase diagram of the Bi-Cu-Pb ternary system was calculated by the CALPHAD method using binary thermodynamic parameters included in the COST 531 database. The results include liquidus projection, invariant equilibria and three vertical sections with molar ratio Cu:Pb = 1, Cu:Pb = 1:3 and Bi:Cu = 1. Alloys, with compositions along three predicted vertical sections, were measured using differential scanning calorimetry (DSC). The experimentally determined phase transition temperatures were compared with calculated results and good mutual agreement was noticed.

  20. Modeling phase equilibria for acid gas mixtures using the CPA equation of state. Part II: Binary mixtures with CO2

    DEFF Research Database (Denmark)

    Tsivintzelis, Ioannis; Kontogeorgis, Georgios; Michelsen, Michael Locht

    2011-01-01

    In Part I of this series of articles, the study of H2S mixtures has been presented with CPA. In this study the phase behavior of CO2 containing mixtures is modeled. Binary mixtures with water, alcohols, glycols and hydrocarbons are investigated. Both phase equilibria (vapor–liquid and liquid–liqu...

  1. Phase equilibria and thermodynamic modeling of ethane and propane hydrates in porous silica gels.

    Science.gov (United States)

    Seo, Yongwon; Lee, Seungmin; Cha, Inuk; Lee, Ju Dong; Lee, Huen

    2009-04-23

    In the present study, we examined the active role of porous silica gels when used as natural gas storage and transportation media. We adopted the dispersed water in silica gel pores to substantially enhance active surface for contacting and encaging gas molecules. We measured the three-phase hydrate (H)-water-rich liquid (L(W))-vapor (V) equilibria of C(2)H(6) and C(3)H(8) hydrates in 6.0, 15.0, 30.0, and 100.0 nm silica gel pores to investigate the effect of geometrical constraints on gas hydrate phase equilibria. At specified temperatures, the hydrate stability region is shifted to a higher pressure region depending on pore size when compared with those of bulk hydrates. Through application of the Gibbs-Thomson relationship to the experimental data, we determined the values for the C(2)H(6) hydrate-water and C(3)H(8) hydrate-water interfacial tensions to be 39 +/- 2 and 45 +/- 1 mJ/m(2), respectively. By using these values, the calculation values were in good agreement with the experimental ones. The overall results given in this study could also be quite useful in various fields, such as exploitation of natural gas hydrate in marine sediments and sequestration of carbon dioxide into the deep ocean.

  2. Phase equilibria in TlX-Cd(Zn)X (X-S, Se, Te) systems

    International Nuclear Information System (INIS)

    Gusejnov, F.Kh.; Babanly, M.B.; Kuliev, A.A.

    1982-01-01

    The methods of DTA, RPA and measurement of the alloys microhardness have been used to investigate the phase equilibria in the TlX-Zn(Cd)X systems. It is established that the TlZn(Cd)X 2 compounds, the presence of which is mentioned in the literature earlier, do not form in these systems. The TlSe-Zn(Cd)Se systems apply to the simple eutectic type and characterized by digenerated eutectic near the TlSe. Thermodynamical analysis of the liquidus of the TlSe-CdSe and TlTe-Zn(Cd)Te systems in approximation of the regular solutions, taking into account the dissociation of tallium chalcogenides in liquid phase, is made

  3. Experimental determination of the phase equilibria in the Co-Fe-Zr ternary system

    International Nuclear Information System (INIS)

    Wang, C.P.; Yu, Y.; Zhang, H.H.; Hu, H.F.; Liu, X.J.

    2011-01-01

    Research highlights: → We determined four isothermal sections of the Co-Fe-Zr system from 1000 o C to 1300 o C. → No ternary compound was found in the Co-Fe-Zr ternary system. → The solubility of Fe in the liquid phase at 1300 o C is extremely large. → The (Co, Fe) 2 Zr phase form the continuous solution from Co-Zr side to Fe-Zr side. → The solubility of Zr in the fcc (Co, Fe) phase is extremely small. - Abstract: The phase equilibria in the Co-Fe-Zr ternary system were investigated by means of optical microscopy (OM), electron probe microanalysis (EPMA), X-ray diffraction (XRD), and differential scanning calorimetry (DSC) on equilibrated ternary alloys. Four isothermal sections of the Co-Fe-Zr ternary system at 1300 o C, 1200 o C, 1100 o C and 1000 o C were experimentally established. The experimental results indicate that (1) no ternary compound was found in this system; (2) the solubility of Fe in the liquid phase of the Co-rich corner at 1300 o C is extremely large; (3) the liquid phase in the Zr-rich corner and the (Co,Fe) 2 Zr phase form the continuous solid solutions from the Co-Zr side to the Fe-Zr side; (4) the solubility of Zr in the fcc (Co, Fe) phase is extremely small.

  4. Experimental investigation of the phase equilibria in the Co-Fe-Ti ternary system

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Chaohui; Chen, Chong; Peng, Yingbiao; Du, Yong; Li, Kun [Central South Univ., State Key of Powder Metallurgy, Changsha (China); Lu, Xingxu [Central South Univ., State Key of Powder Metallurgy, Changsha (China); Central South Univ., School of Materials Science and Engineering, Changsha (China)

    2015-08-15

    Phase equilibria in the Co-Fe-Ti ternary system were investigated by means of the equilibrated alloy method with X-ray powder diffraction and electron probe microanalysis. No ternary compounds were found. The experimental results indicated the existence of seven two-phase and one three-phase regions at 600 C, five two-phase and two three-phase regions at 800 C, and six two-phase and two three-phase regions at 950 C. The solubility of Co in TiFe{sub 2} was determined to be larger than 54 at.% at all investigated temperatures, and the solubilities of Fe in TiCo{sub 3} and Ti{sub 2}Co showed an appreciable increase with increasing temperature. The three-phase equilibrium in the Ti-rich corner at 800 C was revealed to be ((β-Ti) + Ti(Fe, Co) + Ti{sub 2}Co) rather than ((α-Ti) + Ti(Fe, Co) + Ti{sub 2}Co) reported in previous investigations. Based on the experimental data obtained in the present work, three isothermal sections at 600, 800 and 950 C were established.

  5. Experimental investigation of phase equilibria in the Co-Ni-Zr ternary system

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xingjun; Yang, Shuiyuan; Yu, Wenjie; Wang, Cuiping [Xiamen Univ. (China). Fujian Key Laboratory of Materials Genome; Xiong, Huaping; Cheng, Yaoyong; Wu, Xin [Beijing Institute of Aeronautical Materials (China). Div. of Welding and Forging

    2016-10-15

    The phase equilibria of the Co-Ni-Zr ternary system at 1 000 C, 1 100 C and 1 200 C were experimentally investigated by means of back-scattered electron imaging, electron probe microanalysis and X-ray diffraction on the equilibrated ternary alloys. In this study, no ternary compound is found. The (αCo, Ni) phase region extends from the Ni-rich corner to the Co-rich corner with small solubility of Zr at three sections. At 1 000 C and 1 100 C, Ni{sub 5}Zr, Co{sub 2}Zr and Ni{sub 10}Zr{sub 7} phases have large solid solution ranges, but Ni{sub 10}Zr{sub 7} phase disappears at 1 200 C. The Ni{sub 7}Zr{sub 2}, NiZr, Co{sub 11}Zr{sub 2}, Co{sub 23}Zr{sub 6} and CoZr phases exhibit nearly linear compounds in the studied sections, and have large composition ranges. Additionally, some differences in phase relationship exist among the above three isothermal sections.

  6. Phase equilibria and thermodynamic functions for Ag-Hg and Cu-Hg binary systems

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yajun, E-mail: yajunliu@gatech.edu [School of Materials and Energy, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Wang, Guan [School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Wang, Jiang [School of Materials Science and Engineering, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China); Chen, Yang [Mining, Metallurgy and Materials Research Department, General Research Institute for Nonferrous Metals, Beijing 100088 (China); Long, Zhaohui [School of Mechanical Engineering, Xiangtan University, Xiangtan, Hunan 411105 (China)

    2012-11-10

    Highlights: Black-Right-Pointing-Pointer The thermodynamic properties of Ag-Hg and Cu-Hg are explored in order to facilitate dental materials design. Black-Right-Pointing-Pointer A self-consistent set of thermodynamic parameters is obtained. Black-Right-Pointing-Pointer The experimental information can be well reproduced by the optimized thermodynamic data. - Abstract: In order to facilitate the computational design of new amalgams for novel dental alloys, the phase equilibria, phase diagrams and thermodynamic functions for Ag-Hg and Cu-Hg binary systems are explored in this work, based on the CALPHAD framework and experimental characterizations. The Gibbs free energies of the solution phases as well as the stoichiometric phases are calculated, with the aid of enthalpies of mixing, activities, enthalpies of formation, and phase equilibrium data. The thermodynamic descriptions provided in this work enable the stabilities of each phase at various temperatures and compositions to be well described, which contribute to the establishment of a general database to design novel metallic dental materials.

  7. Phase equilibria and thermodynamic functions for Ag–Hg and Cu–Hg binary systems

    International Nuclear Information System (INIS)

    Liu, Yajun; Wang, Guan; Wang, Jiang; Chen, Yang; Long, Zhaohui

    2012-01-01

    Highlights: ► The thermodynamic properties of Ag–Hg and Cu–Hg are explored in order to facilitate dental materials design. ► A self-consistent set of thermodynamic parameters is obtained. ► The experimental information can be well reproduced by the optimized thermodynamic data. - Abstract: In order to facilitate the computational design of new amalgams for novel dental alloys, the phase equilibria, phase diagrams and thermodynamic functions for Ag–Hg and Cu–Hg binary systems are explored in this work, based on the CALPHAD framework and experimental characterizations. The Gibbs free energies of the solution phases as well as the stoichiometric phases are calculated, with the aid of enthalpies of mixing, activities, enthalpies of formation, and phase equilibrium data. The thermodynamic descriptions provided in this work enable the stabilities of each phase at various temperatures and compositions to be well described, which contribute to the establishment of a general database to design novel metallic dental materials.

  8. Experimental investigation of phase equilibria in the Cu–Ni–Si ternary system

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xingjun; Xiang, Shulin; Yang, Shuiyuan; Shi, Rongpei; Wang, Cuiping, E-mail: wangcp@xmu.edu.cn

    2013-11-25

    Highlights: •Three isothermal sections of the Cu–Ni–Si system have been investigated. •The ternary compound τ{sub 1} and the liquid phase are confirmed at 1073 K. •The γ (Cu{sub 5}Si) and θ (Ni{sub 2}Si) phases can be stabilized at higher or lower temperatures. -- Abstract: The phase equilibria in the Cu–Ni–Si ternary system have been investigated experimentally by means of electron probe microanalysis (EPMA), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analysis on equilibrated ternary alloys. Three isothermal sections at 1073, 1173 and 1273 K are determined in the whole composition range. The existence of liquid phase and the ternary compound τ{sub 1} is confirmed at 1073 K. The binary γ (Cu{sub 5}Si), γ (Ni{sub 31}Si{sub 12}), δ (Ni{sub 2}Si) and θ (Ni{sub 2}Si) phases exhibit a considerable solubility of a third element. In addition, the γ (Cu{sub 5}Si) and θ (Ni{sub 2}Si) phases can be stabilized by the addition of Ni and Cu, respectively.

  9. Phase equilibria modeling of methanol-containing systems with the CPA and sPC-SAFT equations of state

    DEFF Research Database (Denmark)

    Tybjerg, Peter Chr. V.; Kontogeorgis, Georgios; Michelsen, Michael Locht

    2010-01-01

    Proper representation at various conditions of phase equilibria of methanol-containing mixtures (with hydrocarbons, water, etc.) is Important for oil flow assurance purposes In this work two association equations of state. CPA and sPC-SAFT, are applied to methanol-containing mixtures The purpose ...

  10. Modelling of phase equilibria for associating mixtures using an equation of state

    International Nuclear Information System (INIS)

    Ferreira, Olga; Brignole, Esteban A.; Macedo, Eugenia A.

    2004-01-01

    In the present work, the group contribution with association equation of state (GCA-EoS) is extended to represent phase equilibria in mixtures containing acids, esters, and ketones, with water, alcohols, and any number of inert components. Association effects are represented by a group-contribution approach. Self- and cross-association between the associating groups present in these mixtures are considered. The GCA-EoS model is compared to the group-contribution method MHV2, which does not take into account explicitly association effects. The results obtained with the GCA-EoS model are, in general, more accurate when compared to the ones achieved by the MHV2 equation with less number of parameters. Model predictions are presented for binary self- and cross-associating mixtures

  11. Melt-gas phase equilibria and state diagrams of the selenium-tellurium system

    Science.gov (United States)

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

    2017-05-01

    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.

  12. Phase equilibria, crystal structure and oxygen content of intermediate phases in the Y-Ba-Co-O system

    OpenAIRE

    Urusova, A. S.; Cherepanov, V. A.; Aksenova, T. V.; Gavrilova, L. Y.; Kiselev, E. A.

    2013-01-01

    The phase equilibria in the Y-Ba-Co-O system were systematically studied at 1373 K in air. The intermediate phases formed in the Y-Ba-Co-O system at 1373 K in air were: YBaCo2O5+δ, YBaCo4O 7 and BaCo1-yYyO3-δ (0.09≤y≤0.42). It was shown that YBaCo2O5+δ possesses tetragonal structure with the 3ap×3a p×2ap superstructure (sp. gr. P4/mmm). High-temperature X-ray diffraction analysis of the YBaCo2O 5+δ in the temperature range from 298 K up to 1073 K under Po2=0.21 atm has not shown any phase tra...

  13. Solid-state phase equilibria in the Fe-Pt-Pr ternary system at 1173 K

    International Nuclear Information System (INIS)

    Ren Jing; Gu Zhengfei; Cheng Gang; Zhou Huaiying

    2005-01-01

    The solid-state phase equilibria in the Fe-Pt-Pr ternary system at 1173 K (Pr ≤ 70%) were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS) techniques. The 1173 K isothermal section consists of 13 single-phase regions, 22 two-phase regions and 10 three-phase regions. At 1173 K, we have observed that the maximum solid solubility of Pt in α-Fe is below 1.5 at.% and the solid solution region of Pt in γ-Fe is from 2 to 35 at.%; the maximum solid solubility of Fe in Pt is 18 at.%. The maximum solubility of Fe in PrPt 5 , PrPt 3 , PrPt 2 , Pr 3 Pt 4 , PrPt, Pr 3 Pt 2 and Pr 7 Pt 3 is below 1 at.%. The maximum solubility of Pr in α-(Fe, Pt), γ-(Fe, Pt), FePt, FePt 3 and (Pt, Fe) (the solid solution of Fe in Pt) is 6, 2, 4, 4.5 and 1.5 at.%, respectively. In this work, it is found that the phase Pr 3 Pt 4 does not exist in the ternary system. The binary compounds Fe 7 Pr and Fe 2 Pr and any new ternary compounds were not observed

  14. Phase equilibria of the Al-Pr-Zr ternary system at 773 K

    Energy Technology Data Exchange (ETDEWEB)

    She, Jia [Laboratory of Nonferrous Metal Materials and New Processing Technology, Ministry of Education, Guangxi University, Nanning, Guangxi 530004 (China); Zhan, Yongzhong, E-mail: zyzmatres@yahoo.com.c [Laboratory of Nonferrous Metal Materials and New Processing Technology, Ministry of Education, Guangxi University, Nanning, Guangxi 530004 (China); Li, Chunliu [Laboratory of Nonferrous Metal Materials and New Processing Technology, Ministry of Education, Guangxi University, Nanning, Guangxi 530004 (China); Du, Yong; Xu, Honghui; He, Yuehui [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China)

    2010-07-30

    The phase equilibria of the Al-Pr-Zr ternary system at 773 K have been investigated mainly by means of X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and differential thermal analysis (DTA). The 14 binary compounds, i.e. AlZr{sub 3}, AlZr{sub 2}, Al{sub 2}Zr{sub 3}, Al{sub 3}Zr{sub 4}, AlZr, Al{sub 3}Zr{sub 2}, Al{sub 2}Zr, Al{sub 3}Zr, {alpha}-Al{sub 11}Pr{sub 3}, Al{sub 3}Pr, Al{sub 2}Pr, {beta}-AlPr, AlPr{sub 2} and {beta}-AlPr{sub 3} were confirmed. No binary compound was found in the Pr-Zr binary system. The result shows that the isothermal section of the Al-Pr-Zr ternary system at 773 K consists of 17 single-phase regions, 31 two-phase regions and 15 three-phase regions. All the intermediate compounds phases in this system have not a remarkable solid solution at 773 K. No ternary compound is found in this work.

  15. Phase equilibria of the Al-Pr-Zr ternary system at 773 K

    International Nuclear Information System (INIS)

    She, Jia; Zhan, Yongzhong; Li, Chunliu; Du, Yong; Xu, Honghui; He, Yuehui

    2010-01-01

    The phase equilibria of the Al-Pr-Zr ternary system at 773 K have been investigated mainly by means of X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and differential thermal analysis (DTA). The 14 binary compounds, i.e. AlZr 3 , AlZr 2 , Al 2 Zr 3 , Al 3 Zr 4 , AlZr, Al 3 Zr 2 , Al 2 Zr, Al 3 Zr, α-Al 11 Pr 3 , Al 3 Pr, Al 2 Pr, β-AlPr, AlPr 2 and β-AlPr 3 were confirmed. No binary compound was found in the Pr-Zr binary system. The result shows that the isothermal section of the Al-Pr-Zr ternary system at 773 K consists of 17 single-phase regions, 31 two-phase regions and 15 three-phase regions. All the intermediate compounds phases in this system have not a remarkable solid solution at 773 K. No ternary compound is found in this work.

  16. The calculation of phase equilibria of oxide core-concrete systems

    International Nuclear Information System (INIS)

    Ball, R.G.J.; Mignanelli, M.A.; Barry, T.I.; Gisby, J.A.

    1993-01-01

    Thermodynamic models have been developed to describe the phase equilibria of oxide solutions appropriate for the understanding of the chemical interactions between nuclear reactor core debris and concrete. For this purpose, the Gibbs energy of the liquid phase is described by the inclusion of associate species and nonideal interactions between the components and associate species. Assessments of the thermodynamic and phase equilibrium data for the subsystems of the CaO-Al 2 O 3 -SiO 2 -UO 2 -ZrO 2 system have been used to obtain a thermodynamic description of the crystalline and liquid phases in good agreement with published data. The data for the subsystems have then been combined, using well established principles, to predict the phase relationships in the ternary and quaternary sytsems and in the overall quinary system. The results show that he overall system cannot properly be treated as a pseudo-ideal liquid and solid solution, as used in some computer codes which attempt to model the physics and chemistry of core-concrete interactions. The limitations of the current model are discussed. (orig.)

  17. Phase equilibria in the ternary In-Ni-Sn system at 700 °C.

    Science.gov (United States)

    Schmetterer, C; Zemanova, A; Flandorfer, H; Kroupa, A; Ipser, H

    2013-04-01

    The phase equilibria of the ternary system In-Ni-Sn were investigated experimentally at 700 °C using X-ray diffraction (XRD) and scanning electron microscopy (SEM) including electron micro probe analysis (EMPA) and energy dispersive X-ray spectroscopy (EDX). A corresponding isothermal section was established based on these results. This particular temperature was chosen because it allowed obtaining reliable results within reasonable time. The existence of the ternary phase InNi 6 Sn 5 was confirmed whereas the ternary compound In 2 NiSn, reported earlier in literature, was found to be part of a large solid solution field based on binary InNi. The ternary solubility of the binary phases was established, and continuous solid solutions were found between the isostructural phases Ni 3 Sn LT and InNi 3 as well as between Ni 3 Sn 2 HT and InNi 2 . In addition, this isothermal section could be well reproduced by CALPHAD modelling. The resulting calculated isotherm at 700 °C is presented, too, and compared with the experimental results.

  18. The heat-capacity of ilmenite and phase equilibria in the system Fe-T-O

    Science.gov (United States)

    Anovitz, Lawrence M.; Treiman, A.H.; Essene, E.J.; Hemingway, B.S.; Westrum, E.F.; Wall, V.J.; Burriel, R.; Bohlen, S.R.

    1985-01-01

    Low temperature adiabatic calorimetry and high temperature differential scanning calorimetry have been used to measure the heat-capacity of ilmenite (FeTiO3) from 5 to 1000 K. These measurements yield S2980 = 108.9 J/(mol ?? K). Calculations from published experimental data on the reduction of ilmenite yield ??2980(I1) = -1153.9 kJ/(mol ?? K). These new data, combined with available experimental and thermodynamic data for other phases, have been used to calculate phase equilibria in the system Fe-Ti-O. Calculations for the subsystem Ti-O show that extremely low values of f{hook}O2 are necessary to stabilize TiO, the mineral hongquiite reported from the Tao district in China. This mineral may not be TiO, and it should be re-examined for substitution of other elements such as N or C. Consideration of solid-solution models for phases in the system Fe-Ti-O allows derivation of a new thermometer/oxybarometer for assemblages of ferropseudobrookite-pseudobrookitess and hematite-ilmenitess. Preliminary application of this new thermometer/oxybarometer to lunar and terrestrial lavas gives reasonable estimates of oxygen fugacities, but generally yields subsolidus temperatures, suggesting re-equilibration of one or more phases during cooling. ?? 1985.

  19. Atomic Origins of Monoclinic-Tetragonal (Rutile) Phase Transition in Doped VO 2 Nanowires

    KAUST Repository

    Asayesh-Ardakani, Hasti

    2015-10-12

    There has been long-standing interest in tuning the metal-insulator phase transition in vanadium dioxide (VO) via the addition of chemical dopants. However, the underlying mechanisms by which doping elements regulate the phase transition in VO are poorly understood. Taking advantage of aberration-corrected scanning transmission electron microscopy, we reveal the atomistic origins by which tungsten (W) dopants influence the phase transition in single crystalline WVO nanowires. Our atomically resolved strain maps clearly show the localized strain normal to the (122¯) lattice planes of the low W-doped monoclinic structure (insulator). These strain maps demonstrate how anisotropic localized stress created by dopants in the monoclinic structure accelerates the phase transition and lead to relaxation of structure in tetragonal form. In contrast, the strain distribution in the high W-doped VO structure is relatively uniform as a result of transition to tetragonal (metallic) phase. The directional strain gradients are furthermore corroborated by density functional theory calculations that show the energetic consequences of distortions to the local structure. These findings pave the roadmap for lattice-stress engineering of the MIT behavior in strongly correlated materials for specific applications such as ultrafast electronic switches and electro-optical sensors.

  20. Atomic Origins of Monoclinic-Tetragonal (Rutile) Phase Transition in Doped VO2 Nanowires.

    Science.gov (United States)

    Asayesh-Ardakani, Hasti; Nie, Anmin; Marley, Peter M; Zhu, Yihan; Phillips, Patrick J; Singh, Sujay; Mashayek, Farzad; Sambandamurthy, Ganapathy; Low, Ke-Bin; Klie, Robert F; Banerjee, Sarbajit; Odegard, Gregory M; Shahbazian-Yassar, Reza

    2015-11-11

    There has been long-standing interest in tuning the metal-insulator phase transition in vanadium dioxide (VO2) via the addition of chemical dopants. However, the underlying mechanisms by which doping elements regulate the phase transition in VO2 are poorly understood. Taking advantage of aberration-corrected scanning transmission electron microscopy, we reveal the atomistic origins by which tungsten (W) dopants influence the phase transition in single crystalline WxV1-xO2 nanowires. Our atomically resolved strain maps clearly show the localized strain normal to the (122̅) lattice planes of the low W-doped monoclinic structure (insulator). These strain maps demonstrate how anisotropic localized stress created by dopants in the monoclinic structure accelerates the phase transition and lead to relaxation of structure in tetragonal form. In contrast, the strain distribution in the high W-doped VO2 structure is relatively uniform as a result of transition to tetragonal (metallic) phase. The directional strain gradients are furthermore corroborated by density functional theory calculations that show the energetic consequences of distortions to the local structure. These findings pave the roadmap for lattice-stress engineering of the MIT behavior in strongly correlated materials for specific applications such as ultrafast electronic switches and electro-optical sensors.

  1. Atomic Origins of Monoclinic-Tetragonal (Rutile) Phase Transition in Doped VO 2 Nanowires

    KAUST Repository

    Asayesh-Ardakani, Hasti; Nie, Anmin; Marley, Peter M.; Zhu, Yihan; Phillips, Patrick J.; Singh, Sujay; Mashayek, Farzad; Sambandamurthy, Ganapathy; Low, Ke Bin; Klie, Robert F.; Banerjee, Sarbajit; Odegard, Gregory M.; Shahbazian-Yassar, Reza

    2015-01-01

    There has been long-standing interest in tuning the metal-insulator phase transition in vanadium dioxide (VO) via the addition of chemical dopants. However, the underlying mechanisms by which doping elements regulate the phase transition in VO are poorly understood. Taking advantage of aberration-corrected scanning transmission electron microscopy, we reveal the atomistic origins by which tungsten (W) dopants influence the phase transition in single crystalline WVO nanowires. Our atomically resolved strain maps clearly show the localized strain normal to the (122¯) lattice planes of the low W-doped monoclinic structure (insulator). These strain maps demonstrate how anisotropic localized stress created by dopants in the monoclinic structure accelerates the phase transition and lead to relaxation of structure in tetragonal form. In contrast, the strain distribution in the high W-doped VO structure is relatively uniform as a result of transition to tetragonal (metallic) phase. The directional strain gradients are furthermore corroborated by density functional theory calculations that show the energetic consequences of distortions to the local structure. These findings pave the roadmap for lattice-stress engineering of the MIT behavior in strongly correlated materials for specific applications such as ultrafast electronic switches and electro-optical sensors.

  2. Influence of the temperature on the (liquid + liquid) phase equilibria of (water + 1-propanl + linalool or geraniol)

    International Nuclear Information System (INIS)

    Wan, Li; Li, Hengde; Huang, Cheng; Feng, Yuqing; Chu, Guoqiang; Zheng, Yuying; Tan, Wei; Qin, Yanlin; Sun, Dalei; Fang, Yanxiong

    2017-01-01

    Highlights: • Ternary LLEs containing linalool and geraniol are presented. • Distribution ratios of 1-propanol in the mixtures are examined. • Influence of the temperature on the LLE is studied. • The LLE data were correlated using the NRTL and UNIQUAC models. - Abstract: Linalool and geraniol are the primary components of rose oil, palmarosa oil, and citronella oil and many other essential oils, and two important compounds used in the flavour and fragrance, cosmetic or pharmaceutical industries. Phase equilibria (LLE, VLE, solubility, etc.) and related thermodynamic properties of a mixture are essential in the processes design and control of mass transfer process. In this work, experimental (liquid + liquid) equilibria data of the systems (water + 1-propanl + linalool) and (water + 1-propanl + geraniol) are presented. The (liquid + liquid) equilibria of both systems were determined with a tie-line method at T = (283.15, 298.15 and 313.15) K under atmospheric pressure. The well-known Hand, Bachman and Othmer–Tobias equations were used to test the reliability of the experimental values. The influence of the temperature on the (liquid + liquid) phase equilibria of the mixtures, the binodal curves and distribution ratios of 1-propanl are shown and discussed. Moreover, the NRTL and UNIQUAC models were applied to fit the data for both ternary systems. The interaction parameters obtained from both models successfully correlated the equilibrium compositions. Furthermore, the ternary systems could be represented using the binary parameters of the thermodynamic model with a function of temperature.

  3. Growth of anatase and rutile phase TiO{sub 2} nanoparticles using pulsed laser ablation in liquid: Influence of surfactant addition and ablation time variation

    Energy Technology Data Exchange (ETDEWEB)

    Chaturvedi, Amita, E-mail: amita-chaturvedi@rrcat.gov.in [Laser Material Processing Division, Raja Ramanna Centre for Advanced Technology, Indore 452013, MP (India); Joshi, M.P. [Laser Material Processing Division, Raja Ramanna Centre for Advanced Technology, Indore 452013, MP (India); Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai – 400094 (India); Mondal, P.; Sinha, A.K.; Srivastava, A.K. [Indus Synchrotron Utilization Division, Raja Ramanna Centre for Advanced Technology, Indore 452013, MP (India)

    2017-02-28

    Highlights: • Ablations of Ti metal target were carried out in DI water and in 0.001 M SDS solution for different times using PLAL process. • Different characterization studies have been carried out to confirm the growth of TiO{sub 2} nanoparticles in both the liquid mediums. • Anatase phase TiO{sub 2} nanoparticles were obtained in DI water and rutile phase in 0.001 M SDS aqueous solution. • In surfactant solution, longer time ablation leads depletion of SDS molecules causes growth of anatase phase for 90 min. • Our studies confirmed the role of liquid ambience conditions variation over the different phase formations of nanoparticles. - Abstract: Titanium dioxide (TiO{sub 2}) nanoparticles were grown using nanosecond pulsed laser ablation of Ti target in DI water and in 0.001 M sodium dodecyl sulfate (SDS) surfactant aqueous solution. Growth was carried out with varying ablation times i. e. 30 min, 60 min and 90 min. The objective of our study was to investigate the influence of variations in liquid ambience conditions on the growth of the nanoparticles in a pulsed laser ablation in liquid (PLAL) process. Size, composition and optical properties of the grown TiO{sub 2} nanoparticles were investigated using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), optical absorption, photoluminescence (PL) spectroscopy and X-ray diffraction (XRD) studies. The obtained nanoparticles of TiO{sub 2} were found almost spherical in shape and polycrystalline in nature in both the liquid mediums i.e. DI water and aqueous solution of surfactant. Nanoparticles number density was also found to increase with increasing ablation time in both the liquid mediums. However crystalline phase of the grown TiO{sub 2} nanoparticles differs with the change in liquid ambience conditions. Selected area electron diffraction (SAED), PL and XRD studies suggest that DI water ambience is favorable for the growth of anatase phase TiO{sub 2} nanoparticles for all

  4. Survey of the calculation of phase equilibria with the aid of the UNIFAC-method

    Energy Technology Data Exchange (ETDEWEB)

    Gmehling, J.; Rasmussen, P.; Fredenslund, A.

    1981-09-01

    In the design of diffusional separation processes and for many other practical purposes one needs quantitative estimates of phase equilibrium compositions. These compositions can today be predicted with good results using modern, two-parameter models for the excess Gibbs energy. However, since the number of different multicomponent mixtures of interest in chemical technology is very large, it is in practise often not possible to find experimental data in the literature for all the possible binary combinations. In these cases it is necessary to use a predictive approach. Today, group-contribution methods such as ASOG and UNIFAC may be used with confidence to predict liquid phase excess Gibbs energies. In these methods, the mixture is assumed to consist not of molecules but of the functional groups which, when added form the parent molecules. This has the advantage that a large number of mixtures of interest in chemical technology can be described in terms of relatively few parameters characterizing the interactions between the groups. This review article demonstrates the application of the UNIFAC method to various practical problems within phase equilibria. The UNIFAC method applies to mixtures of nonelectrolytes in the temperature range of 275-425 K and at pressures up to 10 bar.

  5. Evaluation of ΔGsub(f) values for unstable compounds: a Fortran program for the calculation of ternary phase equilibria

    International Nuclear Information System (INIS)

    Throop, G.J.; Rogl, P.; Rudy, E.

    1978-01-01

    A Fortran IV program was set up for the calculation of phase equilibria and tieline distributions in ternary systems of the type: transition metal-transition metal-nonmetal (interstitial type of solid solutions). The method offers the possibility of determining the thermodynamic values for unstable compounds through their influence upon ternary phase equilibria. The variation of the free enthalpy of formation of ternary solid solutions is calculated as a function of nonmetal content, thus describing the actual curvature of the phase boundaries. The integral and partial molar free enthalpies of formation of binary nonstoichiometric compounds and of phase solutions are expressed as analytical functions of the nonmetal content within their homogeneity range. The coefficient of these analytical expressions are obtained by the use either of the Wagner-Schottky vacancy model or polynomials second order in composition (parabolic approach). The free energy of formation, ΔGsub(f) has been calculated for the systems Ti-C, Zr-C, and Ta-C. Calculations of the ternary phase equilibria yielded the values for ΔGsub(f) for the unstable compounds Ti 2 C at 1500 0 C and Zr 2 C at 1775 0 C of -22.3 and 22.7 kcal g atom metal respectively. These values were used for the calculation of isothermal sections within the ternary systems Ti-Ta-C (at 1500 0 C) and Zr-Ta-C (at 1775 0 C). The ideal case of ternary phase solutions is extended to regular solutions. (author)

  6. Isothermal phase equilibria for the (HFC-32 + HFC-134a) mixed-gas hydrate system

    International Nuclear Information System (INIS)

    Miyauchi, Hiroshi; Yasuda, Kenjiro; Matsumoto, Yuuki; Hashimoto, Shunsuke; Sugahara, Takeshi; Ohgaki, Kazunari

    2012-01-01

    Highlights: ► Structural phase transition results in the heterogeneous azeotropic-like behaviour. ► HFC-134a molecules, in spite of an s-II former, occupy the large cages of s-I. ► Negative azeotropic-like behaviour becomes more remarkable at higher temperatures. - Abstract: Isothermal phase equilibria (pressure-composition relations in hydrate, gas, and aqueous phases) in the {difluoromethane (HFC-32) + 1,1,1,2-tetrafluoroethane (HFC-134a)} mixed-gas hydrate system were measured at the temperatures 274.15 K, 279.15 K, and 283.15 K. The heterogeneous azeotropic-like behaviour derived from the structural phase transition of (HFC-32 + HFC-134a) mixed-gas hydrates appears over the whole temperature range of the present study. In addition to the heterogeneous azeotropic-like behaviour, the isothermal phase equilibrium curves of the (HFC-32 + HFC-134a) mixed-gas hydrate system exhibit the negative homogeneous azeotropic-like behaviour at temperatures 279.15 K and 283.15 K. The negative azeotropic-like behaviour, which becomes more remarkable at higher temperatures, results in the lower equilibrium pressure of (HFC-32 + HFC-134a) mixed-gas hydrates than those of both simple HFC-32 and HFC-134a hydrates. Although the HFC-134a molecule forms the simple structure-II hydrate at the temperatures, the present findings reveal that HFC-134a molecules occupy a part of the large cages of the structure-I mixed-gas hydrate.

  7. Phase equilibria constraints on the chemical and physical evolution of the campanian ignimbrite

    Science.gov (United States)

    Fowler, S.J.; Spera, F.J.; Bohrson, W.A.; Belkin, H.E.; de Vivo, B.

    2007-01-01

    The Campanian Ignimbrite is a > 200 km3 trachyte-phonolite pyroclastic deposit that erupted at 39.3 ?? 0.1 ka within the Campi Flegrei west of Naples, Italy. Here we test the hypothesis that Campanian Ignimbrite magma was derived by isobaric crystal fractionation of a parental basaltic trachyandesitic melt that reacted and came into local equilibrium with small amounts (5-10 wt%) of crustal rock (skarns and foid-syenites) during crystallization. Comparison of observed crystal and magma compositions with results of phase equilibria assimilation-fractionation simulations (MELTS) is generally very good. Oxygen fugacity was approximately buffered along QFM+1 (where QFM is the quartz-fayalite-magnetite buffer) during isobaric fractionation at 0.15 GPa (???6 km depth). The parental melt, reconstructed from melt inclusion and host clinopyroxene compositions, is found to be basaltic trachyandesite liquid (51.1 wt% SiO2, 9.3 wt% MgO, 3 wt% H2O). A significant feature of phase equilibria simulations is the existence of a pseudo-invariant temperature, ???883??C, at which the fraction of melt remaining in the system decreases abruptly from ???0.5 to point leads to abrupt changes in the composition, properties (density, dissolved water content), and physical state (viscosity, volume fraction fluid) of melt and magma. A dramatic decrease in melt viscosity (from 1700 Pa s to ???200 Pa s), coupled with a change in the volume fraction of water in magma (from ??? 0.1 to 0.8) and a dramatic decrease in melt and magma density acted as a destabilizing eruption trigger. Thermal models suggest a timescale of ??? 200 kyr from the beginning of fractionation until eruption, leading to an apparent rate of evolved magma generation of about 10-3 km3/year. In situ crystallization and crystal settling in density-stratified regions, as well as in convectively mixed, less evolved subjacent magma, operate rapidly enough to match this apparent volumetric rate of evolved magma production

  8. Tm-doped TiO2 and Tm2Ti2O7 pyrochlore nanoparticles: enhancing the photocatalytic activity of rutile with a pyrochlore phase.

    Science.gov (United States)

    De Los Santos, Desiré M; Navas, Javier; Aguilar, Teresa; Sánchez-Coronilla, Antonio; Fernández-Lorenzo, Concha; Alcántara, Rodrigo; Piñero, Jose Carlos; Blanco, Ginesa; Martín-Calleja, Joaquín

    2015-01-01

    Tm-doped TiO2 nanoparticles were synthesized using a water-controlled hydrolysis reaction. Analysis was performed in order to determine the influence of the dopant concentration and annealing temperature on the phase, crystallinity, and electronic and optical properties of the resulting material. Various characterization techniques were utilized such as X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and UV-vis spectroscopy. For the samples annealed at 773 and 973 K, anatase phase TiO2 was obtained, predominantly internally doped with Tm(3+). ICP-AES showed that a doping concentration of up to 5.8 atom % was obtained without reducing the crystallinity of the samples. The presence of Tm(3+) was confirmed by X-ray photoelectron spectroscopy and UV-vis spectroscopy: the incorporation of Tm(3+) was confirmed by the generation of new absorption bands that could be assigned to Tm(3+) transitions. Furthermore, when the samples were annealed at 1173 K, a pyrochlore phase (Tm2Ti2O7) mixed with TiO2 was obtained with a predominant rutile phase. The photodegradation of methylene blue showed that this pyrochlore phase enhanced the photocatalytic activity of the rutile phase.

  9. Ce-doped nanoparticles of TiO2: Rutile-to-brookite phase transition and evolution of Ce local-structure studied with XRD and XANES

    International Nuclear Information System (INIS)

    Kityakarn, Sutasinee; Worayingyong, Attera; Suramitr, Anwaraporn; Smith, M.F.

    2013-01-01

    The crystal and electronic structural changes undergone by TiO 2 nanoparticles when Ce is introduced were studied using X-ray diffraction (XRD) and X-ray absorption near-edge spectroscopy (XANES). A small amount of Ce (less than 1% molar concentration) resulted in i/a significant reduction of the average size of the TiO 2 nanoparticles and ii/a phase transition in which brookite replaced rutile as the minority phase component (anatase was the majority phase component at all Ce concentrations studied up to 10% molar concentration). The Ce L3 edge XANES revealed changes in the local environment of Ce impurities. As Ce concentration was increased the fraction of Ce that have formal valence of +3 decreased and, for the remaining Ce with valence +4, the 4f orbitals became less-strongly hybridized with the p-orbitals of oxygen neighbors. The results have implications for photocatalytic and gas sensing properties of Ce-doped TiO 2 . - Highlights: ► Ce-doping: TiO 2 nanoparticles shrink and minority phase changes rutile-> brookite. ► XANES reveals phase change for arbitrarily small particles (while XRD fails). ► As Ce added: fraction of Ce +3 dopants falls, hybridization of Ce +4 with O weakens

  10. Correlation of phase equilibria for water + hydrocarbon systems at high temperatures and pressures by cubic equation of state

    Energy Technology Data Exchange (ETDEWEB)

    Haruki, Masashi; Yahiro, Yukihito; Higashi, Hidenori; Iwai, Yoshio; Arai, Yasuhiko [Kyushu University, FUkuoka (Japan). Graduate School of Engineering

    1999-08-01

    A modified-Soave-Redlich-Kwong (MSRK) equation of state with an exponent-type mixing rule for the energy parameter and a conventional rule for the size parameter is applied to correlate the phase equilibria for four binary mixtures of water + hydrocarbon (benzene, hexane, decane, and dodecane) systems at high temperatures and pressures. It is noted that good correlation results are obtained by using the mixing rules with interaction parameters between unlike molecules. (author)

  11. Phase equilibria of Al3(Ti,V,Zr) intermetallic system

    International Nuclear Information System (INIS)

    Park, S.I.; Han, S.Z.; Choi, S.K.; Lee, H.M.

    1996-01-01

    Trialuminides such as DO 22 -structured Al 3 Ti are promising candidates as potential materials for elevated temperature applications because of their attractive high temperature strength and excellent oxidation resistance along with their low density. However, in the tetragonal structure, slip systems are restricted due to low symmetry and the primary deformation mode is twinning. And, therefore, monolithic trialuminide compounds have been very impractical to be used as structural materials. When transition elements such as Ti, V and Zr which constitute trialuminides are alloyed in aluminum, they have low solubilities and low diffusion coefficients in the Al matrix. If precipitated as trialuminide intermetallics, they maintain a small lattice mismatch with the Al matrix, which reduces the interfacial energy between matrix and precipitates. As a result, these precipitates would have a large coarsening resistance in the matrix. As most of the previous works have been concentrated on the microstructural stability and mechanical properties, thermochemical properties will be treated in this work. In this study, phase equilibria and diagrams of Al 3 (Ti,V,Zr) systems will be experimentally determined and then thermodynamically analyzed with a hope to extend to the Al-Al 3 (Ti,V,Zr) composite system. This approach will then be used as a guide for alloy design of Al-Al 3 (Ti,V,Zr) composite system

  12. Phase equilibria in the Ni–Al–Ga system at 700 °C

    International Nuclear Information System (INIS)

    Belyavina, N.; Markiv, V.; Nakonechna, O.; Lozovyi, F.

    2014-01-01

    Graphical abstract: - Highlights: • We study phase equilibria in ternary Ni–Al–Ga in the whole concentration range. • Ni(Al,Ga), Ni 2 (Al,Ga) 3 , Ni 5 (Al,Ga) 3 extended solid solutions exist in this system. • Isothermal section (700 °C) of the Ni–Al–Ga system has been constructed. • Small additions of Ga increase compressive strength of Ni 3 (Al,Ga) solid solution. - Abstract: Phase relations in the ternary Ni–Al–Ga system at 700 °C have been established by the X-ray powder diffraction methods. In addition to already known Ni 3 (Al,Ga) continuous solid solution, Ni(Al,Ga) continuous solid solution as well as Ni 2 (Al,Ga) 3 and Ni 5 (Al,Ga) 3 extended solid solutions were found to exist in this system. It was shown that the ternary Ni 2 (Al,Ga) 3 and Ni 5 (Al,Ga) 3 compounds do not belong to the continuous solid solutions because of two-phase gaps on the Ni 2 Al 3 –Ni 2 Ga 3 (∼30–50 at.% Ga) and Ni 5 Al 3 –Ni 5 Ga 3 (∼12–25 at.% Ga) isolines at 700 °C. Some crystal structure peculiarities such as atomic ordering–disordering and presence of structural vacancies have been revealed for all solid solutions existing in the Ni–Al–Ga system. It was found that the compressive strength of the Ni 3 (Al,Ga) solid solution increases with small additions of gallium (about 2.5 at.%). The isothermal section (700 °C) of the ternary Ni–Al–Ga system including four extended solid solutions (Ni 3 (Al,Ga), Ni 5 (Al,Ga) 3 , Ni(Al,Ga) and Ni 2 (Al,Ga) 3 ) has been constructed and plotted

  13. Phase equilibria in the BaUO3-BaZrO3-BaMoO3 system

    International Nuclear Information System (INIS)

    Kurosaki, Ken; Yamanaka, Shinsuke; Matsuda, Tetsushi; Uno, Masayoshi; Yamamoto, Kazuya; Namekawa, Takashi

    2002-01-01

    The phase equilibria in the pseudo-ternary BaUO 3 -BaZrO 3 -BaMoO 3 system were studied to understand the thermochemical properties of the perovskite type gray oxide phase in high burnup MOX fuel. Thermodynamic equilibrium calculation for the system was performed by using a Chem Sage program under the various oxygen potentials. Solid solutions existing in the system were treated by an ideal solution model. The present calculation results well agreed with the previous reported post irradiation examination results, showing that BaMoO 3 was scarcely included in the gray oxide phase. (author)

  14. Preparation and characterization of phase-pure anatase and rutile TiO2 powder by new chemistry route

    International Nuclear Information System (INIS)

    Pereira, E. A.; Montanhera, M.A.; Paula, F.R.; Spada, E.R.

    2014-01-01

    Titanium dioxide (TiO 2 ) is used in a wire range applications such as photocatalysis and sensor device. In this work is shown a new and effective method for the preparation of TiO 2 nanocrystalline in the crystallographic forms, anatase and rutile. The method involves dissolving the TiOSO 4 powder in H 2 O 2 solution and thermal treatment of amorphous precipitate. The technique of X-ray diffraction was used to follow the structure evolution of amorphous precipitate. Pure anatase structure and rutile are obtained at 600 deg C and 1000 deg C with a grain size estimated 24 and 55 nm respectively. TiO 2 nanoparticles is a promising alternative of the low cost whose potential for solar cells deserve a careful evaluation, especially in hybrid solar cells that employs TiO 2 as electron acceptor and as transport channels. (author)

  15. Enthalpy of phase transition and prediction of phase Equilibria in systems of glycols and glycol ethers

    OpenAIRE

    Esina, Zoya; Miroshnikov, Aleksandr; Korchuganova, Margarita

    2014-01-01

    The PCEAS model was used to study the liquid-solid and liquid-vapor phase transitions at constant pressure in systems containing glycols and glycol ethers. This method is based on minimizing the excess Gibbs energy over the solvation parameter, which takes into account the processes of association of molecules in various phases. To compute the diagrams, the data on enthalpy and phase transition temperatures of pure components are required, while the information about the interactions in the b...

  16. Thermodynamic analysis and phase equilibria investigation in Pb−Zn−Ag system

    Directory of Open Access Journals (Sweden)

    Mitovski Aleksandra M.

    2010-01-01

    Full Text Available Physico-chemical processes that take place during the refining process in the extractive metallurgy of lead, are connected with ternary Pb−Zn−Ag system, which is necessary to study from the theoretical practical and aspects. Such investigation is important from production point of view, because of the phenomena that occur during desilvering of lead which is one of the important stages during lead refining process. Process of lead desilvering binds to ternary system Pb−Zn−Ag, which was the reason for numerous investigations, both from thermodynamic point of view and in terms of testing and determining the phase diagram, bearing in mind the theoretical, and practical importance of knowledge about the processes which are going in investigated system. The paper presents the results of thermodynamic analysis and investigation of phase equilibria of the Pb−Zn−Ag ternary system using the method of thermodynamic predictions and phase diagrams calculations, respectively, and the experimental results of metalography obtained by optical microscopy. Phase diagram of the vertical section Pb−Zn80Ag20 is presented, obtained by CALPHAD calculation methodology, and using PANDAT thermodynamic software, compared to experimental results obtained by DTA analysis. The results show a pronounced break in solubility, which is characteristic for the whole ternary Pb−Zn−Ag system. Also, it can be noticed that the thermodynamic properties follow the behavior of this system, which is expressed through positive deviation of Raoult’s law, pointing to the lack of lead affinity compared to the other two components in the system. The optical microscopy results of the investigated system show the following: - Sample L1 (weight% Pb = 98: the structure of the observed section shows double eutectic (Pbsol+Zn−Agsol which lies in the base of the primary crystals of lead (Pbsol - Samples L2−L5: the structure consists of a dual eutectic (Pbsol+Zn−Agsol and

  17. Phase Equilibria of the Sn-Ni-Si Ternary System and Interfacial Reactions in Sn-(Cu)/Ni-Si Couples

    Science.gov (United States)

    Fang, Gu; Chen, Chih-chi

    2015-07-01

    Interfacial reactions in Sn/Ni-4.5 wt.%Si and Sn-Cu/Ni-4.5 wt.%Si couples at 250°C, and Sn-Ni-Si ternary phase equilibria at 250°C were investigated in this study. Ni-Si alloys, which are nonmagnetic, can be regarded as a diffusion barrier layer material in flip chip packaging. Solder/Ni-4.5 wt.%Si interfacial reactions are crucial to the reliability of soldered joints. Phase equilibria information is essential for development of solder/Ni-Si materials. No ternary compound is present in the Sn-Ni-Si ternary system at 250°C. Extended solubility of Si in the phases Ni3Sn2 and Ni3Sn is 3.8 and 6.1 at.%, respectively. As more Si dissolves in these phases their lattice constants decrease. No noticeable ternary solubility is observed for the other intermetallics. Interfacial reactions in solder/Ni-4.5 wt.%Si are similar to those for solder/Ni. Si does not alter the reaction phases. No Si solubility in the reaction phases was detected, although rates of growth of the reaction phases were reduced. Because the alloy Ni-4.5 wt.%Si reacts more slowly with solders than pure Ni, the Ni-4.5 wt.%Si alloy could be a potential new diffusion barrier layer material for flip chip packaging.

  18. Phase Transformations and Phase Equilibria in the Fe-N System at Temperatures below 573 K

    DEFF Research Database (Denmark)

    Malinov, S.; Böttger, A.J.; Mittemeijer, E.J.

    2001-01-01

    The phase transformations of homogeneous Fe-N alloys of nitrogen contents from 10 to 26 at. pct were investigated by means of X-ray diffraction analysis upon aging in the temperature range from 373 to 473 K. It was found that precipitation of alpha double prime-Fe16N2 below 443 K does not only oc...

  19. Modelling of phase equilibria of glycol ethers mixtures using an association model

    DEFF Research Database (Denmark)

    Garrido, Nuno M.; Folas, Georgios; Kontogeorgis, Georgios

    2008-01-01

    Vapor-liquid and liquid-liquid equilibria of glycol ethers (surfactant) mixtures with hydrocarbons, polar compounds and water are calculated using an association model, the Cubic-Plus-Association Equation of State. Parameters are estimated for several non-ionic surfactants of the polyoxyethylene ...

  20. Thermodynamic modelling of phase equilibria in Al–Ga–P–As system

    Indian Academy of Sciences (India)

    A generalized thermodynamic expression of the liquid Al–Ga–P–As alloys is used in conjunction with the solid solution model in determining the solid–liquid equilibria at 1173 K and 1273 K. The liquid solution model contains thirtyseven parameters. Twentyfour of them pertain to those of the six constituent binaries, twelve ...

  1. Simulation of the high-pressure phase equilibria of hydrocarbon-water/brine systems

    DEFF Research Database (Denmark)

    Zuo, You-Xiang; Stenby, Erling Halfdan; Guo, Tian-Min

    1996-01-01

    The major objectives of this work are: (1) extend the modified Patel-Teja (MPT) equation of state proposed for aqueous electrolyte systems (Zuo and Guo, 1991) to describe the liquid-liquid and vapor-liquid-liquid equilibria of hydrocarbon-water/brine systems through introducing an unconventional...

  2. Heat capacity and phase equilibria of almandine, Fe3Al2Si3O12

    Science.gov (United States)

    Anovitz, Lawrence M.; Essene, E.J.; Metz, G.W.; Bohlen, S.R.; Westrum, E.F.; Hemingway, B.S.

    1993-01-01

    The heat capacity of a synthetic almandine, Fe3Al2Si3O12, was measured from 6 to 350 K using equilibrium, intermittent-heating quasi-adiabatic calorimetry and from 420 to 1000 K using differential scanning calorimetry. These measurements yield Cp298 = 342.80 ?? 1.4 J/mol ?? K and S298o = 342.60 J/mol ?? K. Mo??ssbauer characterizations show the almandine to contain less than 2 ?? 1% of the total iron as Fe3+. X-ray diffraction studies of this synthetic almandine yield a = 11.521 ?? 0.001 A?? and V298o = 115.11 +- 0.01 cm3/mol, somewhat smaller than previously reported. The low-temperature Cp data indicate a lambda transition at 8.7 K related to an antiferromagnetic-paramagnetic transition with TN = 7.5 K. Modeling of the lattice contribution to the total entropy suggests the presence of entropy in excess of that attributable to the effects of lattice vibrations and the magnetic transition. This probably arises from a low-temperature electronic transition (Schottky contribution). Combination of the Cp data with existing thermodynamic and phase equilibrium data on almandine yields ??Gf,298o = -4938.3 kJ/mol and ??Hf,298o= -5261.3 kJ/mol for almandine when calculated from the elements. The equilibrium almandine = hercynite + fayalite + quartz limits the upper T P for almandine and is metastably located at ca. 570??C at P = 1 bar, with a dP dT of +17 bars/??C. This agrees well with reversed experiments on almandine stability when they are corrected for magnetite and hercynite solid-solutions. In {norm of matrix}O2-T space, almandine oxidizes near QFM by the reactions almandine + O2 = magnetite + sillimanite + quartz and almandine + 02 = hercynite + magnetite + quartz. With suitable correction for reduced activities of solid phases, these equilibria provide useful oxygen barometers for medium- to high-grade metamorphic rocks. ?? 1993.

  3. Distinctive toxicity of TiO2 rutile/anatase mixed phase nanoparticles on Caco-2 cells.

    Science.gov (United States)

    Gerloff, Kirsten; Fenoglio, Ivana; Carella, Emanuele; Kolling, Julia; Albrecht, Catrin; Boots, Agnes W; Förster, Irmgard; Schins, Roel P F

    2012-03-19

    Titanium dioxide has a long-standing use as a food additive. Micrometric powders are, e.g., applied as whiteners in confectionary or dairy products. Possible hazards of ingested nanometric TiO(2) particles for humans and the potential influence of varying specific surface area (SSA) are currently under discussion. Five TiO(2)-samples were analyzed for purity, crystallinity, primary particle size, SSA, ζ potential, and aggregation/agglomeration. Their potential to induce cytotoxicity, oxidative stress, and DNA damage was evaluated in human intestinal Caco-2 cells. Only anatase-rutile containing samples, in contrast to the pure anatase samples, induced significant LDH leakage or mild DNA damage (Fpg-comet assay). Evaluation of the metabolic competence of the cells (WST-1 assay) revealed a highly significant correlation between the SSA of the anatase samples and cytotoxicity. The anatase/rutile samples showed higher toxicity per unit surface area than the pure anatase powders. However, none of the samples affected cellular markers of oxidative stress. Our findings suggest that both SSA and crystallinity are critical determinants of TiO(2)-toxicity toward intestinal cells. © 2012 American Chemical Society

  4. 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: ioannis.economou@qatar.tamu.edu [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)

    2015-01-28

    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.

  5. In situ studies of uranium-plutonium mixed oxides. Influence of composition on phase equilibria and thermodynamic properties

    International Nuclear Information System (INIS)

    Strach, Michal

    2015-01-01

    Due to their physical and chemical properties, mixed uranium-plutonium oxides are considered for fuel in 4. generation nuclear reactors. In this frame, complementary experimental studies are necessary to develop a better understanding of the phenomena that take place during fabrication and operation in the reactor. The focus of this work was to study the U-Pu-O phase diagram in a wide range of compositions and temperatures to ameliorate our knowledge of the phase equilibria in this system. Most of experiments were done using in situ X-ray diffraction at elevated temperatures. The control of the oxygen partial pressure during the treatments made it possible to change the oxygen stoichiometry of the sample, which gave us an opportunity to study rapidly different compositions and the processes involved. The experimental approach was coupled with thermodynamic modeling using the CALPHAD method, to precisely plan the experiments and interpret the obtained results. This approach enabled us to enhance the knowledge of phase equilibria in the U-Pu-O system. (author) [fr

  6. An energy stable evolution method for simulating two-phase equilibria of multi-component fluids at constant moles, volume and temperature

    KAUST Repository

    Kou, Jisheng; Sun, Shuyu; Wang, Xiuhua

    2016-01-01

    In this paper, we propose an energy-stable evolution method for the calculation of the phase equilibria under given volume, temperature, and moles (VT-flash). An evolution model for describing the dynamics of two-phase fluid system is based on Fick

  7. Phase equilibria and crystalline structure of compounds in the Lu-Al and Lu-Cu-Al systems

    International Nuclear Information System (INIS)

    Kuz'ma, Yu.B.; Stel'makhovich, B.M.; Galamushka, L.I.

    1992-01-01

    Phase equilibria and crystal structure of compounds in Lu-Al and Lu-Cu-Al systems were studied. Existence of Lu 2 Al compound having the structure of the PbCl 2 type is ascertained. Diagram of phase equilibria of Lu-Cu-Al system at 870 K is plotted. Compounds Lu 2 (Cu,Al) 17 (the Th 2 Zn 17 type structure), Lu(Cu,Al) 5 (CaCu 5 type structure), Lu 6 (Cu,Al) 23 (Th 6 Mn 23 type structure) and ∼ LuCuAl 2 have been prepared for the first time. Investigation of component interaction in Lu-Cu-Al system shows that the system is similar to previously studied systems Dy-Cu-Al and Er-Cu-Al. The main difference consists in the absence of LuCuAl 3 compound with rhombic structure of the CeNi 2+x Sb 2-x type in the system investigated

  8. Equation of state modeling of the phase equilibria of asymmetric CO2+n-alkane binary systems using mixing rules cubic with respect to mole fraction

    DEFF Research Database (Denmark)

    Cismondi, Martin; Mollerup, Jørgen M.; Zabaloy, Marcelo S.

    2010-01-01

    for a great diversity of mixtures. Nevertheless, the models for representing phase equilibria and physico-chemical properties of asymmetric systems may require more flexible mixing rules than the classical quadratic van der Waals (vdW) mixing rules or their equivalent (with regard to the number of available...... interaction parameters) in modern equations of state.In particular, the phase equilibria of binary mixtures containing CO2 and heavy n-alkanes have been studied by an important number of authors and using different types of models, achieving only partially accurate results and realizing the difficulties...

  9. Phase equilibria and stability of the B2 phase in the Ni-Mn-Al and Co-Mn-Al systems

    International Nuclear Information System (INIS)

    Kainuma, R.; Ise, M.; Ishikawa, K.; Ohnuma, I.; Ishida, K.

    1998-01-01

    The phase equilibria and ordering reactions in the composition region up to 50 at.% Al have been investigated in the Ni-Mn-Al and Co-Mn-Al systems at temperatures in the interval 850-1200 C mainly by the diffusion couple method. The compositions of the γ (A1: fcc-Ni, -Co, γ-Mn), γ' (L1 2 : Ni 3 Al), β (B2: NiAl, CoAl, NiMn), β-Mn (A13: β-Mn type), δ-Mn (A2: bcc-Mn) and ε (A3: hcp-(Mn, Al)) phases in equilibrium and the critical boundaries of the A2/B2 continuous ordering transition in the bcc phase region have been determined. It is shown that in the Mn-rich portion of the ternary systems both continuous and discontinuous A2 to B2 ordering transitions exist. The A2+B2 two-phase region in the isothermal sections has a lenticular shape and exists over a wide temperature range. The phase equilibria between the γ, γ', β, β-Mn, δ-Mn and ε phases are presented and the stability of the ordered bcc aluminides is discussed. (orig.)

  10. Elastic energy and metastable phase equilibria for coherent mixtures in cubic systems

    International Nuclear Information System (INIS)

    Williams, R.O.

    1979-02-01

    Expressions were derived for the elastic energy due to coherency for cubic systems for an isotropic structure and for (100) or (111) habit planes for a lamellar structure. For the metastable equilibria the usual tangent compositions are replaced by compositions that are tangent to the elastic energy curve. For a loss of coherency there is an energy decrease due to the elastic effects and a further decrease associated with compositional changes. Information contained within this treatment permits calculation of the x-ray diffraction effects for such structures

  11. Experimental study of the phase equilibria in the Mg–Zn–Ag ternary system at 300 °C

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jian, E-mail: jian.wang@polymtl.ca [Center for Research in Computational Thermochemistry (CRCT), Department of Chemical Engineering, École Polytechnique, Montréal, Québec H3C 3A7 (Canada); Zhang, Yi-Nan [Department of Mechanical Engineering, Concordia University, 1455 De Maisonneuve Blvd. West, Montreal, Quebec H3G 1M8 (Canada); Hudon, Pierre; Jung, In-Ho [Department of Mining and Materials Engineering, McGill University, 3610 University Street, Montreal, Quebec H3A 0C5 (Canada); Medraj, Mamoun [Department of Mechanical Engineering, Concordia University, 1455 De Maisonneuve Blvd. West, Montreal, Quebec H3G 1M8 (Canada); Department of Mechanical and Materials Engineering, Masdar Institute, Masdar City, P.O. Box 54224, Abu Dhabi (United Arab Emirates); Chartrand, Patrice [Center for Research in Computational Thermochemistry (CRCT), Department of Chemical Engineering, École Polytechnique, Montréal, Québec H3C 3A7 (Canada)

    2015-08-05

    Highlights: • The phase equilibria of Mg–Zn–Ag system at 300 °C were determined. • A bcc continuous ternary solid solution forms between MgAg (bcc-B2) and AgZn (bcc-A2) was determined. • The extended solid solubilities of the sub-binary compounds were also determined. - Abstract: The phase equilibria in the Mg–Zn–Ag ternary system at 300 °C were investigated using three diffusion couples and 35 key samples. Scanning electron microscopy (SEM) equipped with energy-dispersive spectroscope (EDS) and X-ray diffraction (XRD) techniques were used for homogeneity ranges and crystal structure determination. Large solid solubility limits, due to substitution among Mg, Zn and Ag atoms in Mg{sub 3}Ag and MgZn{sub 2} phases, were observed in the present work. Solid solubility limits of Ag and Zn in the hcp (Mg) phase were found to be less than 1 at.%. The extended solid solubilities of the Mg{sub 12}Zn{sub 13}, Mg{sub 2}Zn{sub 3}, MgZn{sub 2} (C14), Mg{sub 2}Zn{sub 11}, Ag{sub 5}Zn{sub 8} and hcp (AgZn{sub 3}) sub-binary compounds were also determined in the Mg–Zn–Ag ternary system. In addition, a bcc continuous ternary solid solution forms between MgAg (bcc-B2) and AgZn (bcc-A2) at 300 °C.

  12. Insight into the Am-O Phase Equilibria: A Thermodynamic Study Coupling High-Temperature XRD and CALPHAD Modeling.

    Science.gov (United States)

    Epifano, Enrica; Guéneau, Christine; Belin, Renaud C; Vauchy, Romain; Lebreton, Florent; Richaud, Jean-Christophe; Joly, Alexis; Valot, Christophe; Martin, Philippe M

    2017-07-03

    In the frame of minor actinide transmutation, americium can be diluted in UO 2 and (U, Pu)O 2 fuels burned in fast neutron reactors. The first mandatory step to foresee the influence of Am on the in-reactor behavior of transmutation targets or fuel is to have fundamental knowledge of the Am-O binary system and, in particular, of the AmO 2-x phase. In this study, we coupled HT-XRD (high-temperature X-ray diffraction) experiments with CALPHAD thermodynamic modeling to provide new insights into the structural properties and phase equilibria in the AmO 2-x -AmO 1.61+x -Am 2 O 3 domain. Because of this approach, we were able for the first time to assess the relationships between temperature, lattice parameter, and hypostoichiometry for fcc AmO 2-x . We showed the presence of a hyperstoichiometric existence domain for the bcc AmO 1.61+x phase and the absence of a miscibility gap in the fcc AmO 2-x phase, contrary to previous representations of the phase diagram. Finally, with the new experimental data, a new CALPHAD thermodynamic model of the Am-O system was developed, and an improved version of the phase diagram is presented.

  13. Thermodynamic model for the phase equilibria of gases and brines. Example in the H{sub 2}S-H{sub 2}O-NaCl system

    Energy Technology Data Exchange (ETDEWEB)

    Martinez Reyes, Jose; Gonzalez Partida, Eduardo; Tinoco-Michel, Jorge A [Centro de Geociencias, Universidad Nacional Autonoma de Mexico Campo de Juriquilla, Qro., Mexico, apartado postal 76230 (Mexico); Perez, Renee J; Heidemann, Robert A [Department of Chemical and Petroleum Engineering, University of Calgary, 2500 University Drive, Calgary Alberta, T2N 1N4 (Canada)

    2008-10-01

    We present a thermodynamic model for the phase equilibria of gases and brines, which couples Henry's Law with the Soave-Redlich-Kwong equation of state to reproduce experimental data. In this communication we focus on the H{sub 2}S H{sub 2}O NaCl system.

  14. Performance of predictive models in phase equilibria of complex associating systems: PC-SAFT and CEOS/GE

    Directory of Open Access Journals (Sweden)

    N. Bender

    2013-03-01

    Full Text Available Cubic equations of state combined with excess Gibbs energy predictive models (like UNIFAC and equations of state based on applied statistical mechanics are among the main alternatives for phase equilibria prediction involving polar substances in wide temperature and pressure ranges. In this work, the predictive performances of the PC-SAFT with association contribution and Peng-Robinson (PR combined with UNIFAC (Do through mixing rules are compared. Binary and multi-component systems involving polar and non-polar substances were analyzed. Results were also compared to experimental data available in the literature. Results show a similar predictive performance for PC-SAFT with association and cubic equations combined with UNIFAC (Do through mixing rules. Although PC-SAFT with association requires less parameters, it is more complex and requires more computation time.

  15. Thermodynamic Modeling of Multi-phase Solid–Liquid Equilibria in Industrial-Grade Oils and Fats

    DEFF Research Database (Denmark)

    Hjorth, Jeppe Lindegaard; Miller, Rasmus L.; Woodley, John M.

    2015-01-01

    Compositional thermodynamic phase separation is investigated for industrial-grade vegetable oils with complex compositions. Solid–liquid equilibria have been calculated by utilizing the Margules 2-suffix activity-coefficient model in combination with minimization of the Gibb’s free energy...... of the system. On the basis of quasi-equilibrium solid-fat content (SFC) measurements, a new approach to the estimation of the interaction parameters, needed for the activity-coefficient model, has been developed. The parameters are fitted by matching the SFC of two oils at various degrees of dilution...... and isothermal temperatures. Subsequently, the parameters are successfully validated against three oils, rich in asymmetric and symmetric triacylglycerols (TAG), respectively. The new approach developed is shown to be very flexible, allowing incorporation of additional TAG and polymorphic states. It thereby...

  16. Monosilicide-disilicide-silicon phase equilibria in the nickel-platinum-silicon and nickel-palladium-silicon systems

    Science.gov (United States)

    Loomans, M. E.; Chi, D. Z.; Chua, S. J.

    2004-10-01

    Bulk-phase equilibria in Ni-rich/Si-rich alloys of the Ni-Pt-Si and Ni-Pd-Si systems were investigated. Results suggest that a bulk monosilicide solid solution, containing up to at least 11 at. pct Pt, exists in the Ni-Pt-Si system. Monosilicides containing more than 11 at. pct Pt were not examined. Results from both ternary systems point convincingly to the existence of a NiSi+Si↔NiSi2 eutectoid reaction near 700 °C in the Ni-Si binary system; data from the Ni-Pt-Si system, which yield the more accurate determination of the eutectoid temperature, place it at roughly 710 °C. The Pt and Pd concentrations of monosilicide in equilibrium with disilicide and Si were measured using energy-dispersive spectrometry (EDS) and were found to increase with temperature.

  17. Isothermal sections of phase equilibria diagrams for systems (terbium, dysprosium, holmium)-molybdenum-boron at 1273 K

    International Nuclear Information System (INIS)

    Kuz'ma, Yu.B.; Zakharchuk, N.P.; Maksimova, L.T.

    1988-01-01

    The methods of X-ray analysis are used to study the R-Mo-B (R-Tb, Dy, Ho) systems and isothermal sections of phase equilibria diagrams at 1273 K are plotted. A formation of RMoB 4 (structure of the YCrB 4 type) is confirmed and borides R 3 MoB 7 (structure of the Er 3 CrB 7 type) and ∼ RMo 4 B 8 (of the unknown structure) are obtained for the first time. Borides DyMoB 3 and HoMoB 3 are of the ErMoB 3 structure. Lattice periods of new compounds are indicated. Diffractogrammes of borides Dy 3 MoB 7 and DyMoB 3 are calculated. A peculiarity of components interaction in the systems rare-earth metal-molybdenum-boron is considered

  18. Phase equilibria in the iron oxide-cobalt oxide-phosphorus oxide system

    Science.gov (United States)

    De Guire, Mark R.; Prasanna, T. R. S.; Kalonji, Gretchen; O'Handley, Robert C.

    1987-01-01

    Two novel ternary compounds are noted in the present study of 1000 C solid-state equilibria in the Fe-Co-P-O system's Fe2O3-FePO4-Co3(Po4)2-CoO region: CoFe(PO4)O, which undergoes incongruent melting at 1130 C, and Co3Fe4(PO4)6, whose incongruent melting occurs at 1080 C. The liquidus behavior-related consequences of rapidly solidified cobalt ferrite formation from cobalt ferrite-phosphate melts are discussed with a view to spinel formation. It is suggested that quenching from within the spinel-plus-liquid region may furnish an alternative to quenching a homogeneous melt.

  19. α-NiPt(Al) and phase equilibria in the Ni-Al-Pt system at 1150 deg C

    International Nuclear Information System (INIS)

    Hayashi, S.; Ford, S.I.; Young, D.J.; Sordelet, D.J.; Besser, M.F.; Gleeson, B.

    2005-01-01

    The α-NiPt(Al) phase and its associated equilibria in the Ni-Al-Pt system at 1150 deg C were investigated by analyzing equilibrated bulk alloys and the interdiffusion zones of diffusion couples. Phase constitutions, tie-lines and microstructures were determined using a combination of techniques, including high-energy synchrotron X-ray diffraction, scanning electron microscopy and electron probe microanalysis. A large Pt solubility limit was found to exist in the β-NiAl, ∼42 at.%, and in γ'-Ni 3 Al, ∼32 at.%. The α-NiPt(Al) phase was found to have wide Pt solubility range of about 33-60 at.% and to skew along an almost constant Pt/Al ratio of 1.5. The α-NiPt(Al) has an ordered face-centered tetragonal L1 0 crystal structure, with the Al and Pt atoms found to be preferentially located in the corners and prismatic faces, respectively. The temperature dependence of the lattice parameters and unit cell volume of the α phase were also determined

  20. Phase equilibria and thermodynamics of the Fe–Al–C system: Critical evaluation, experiment and thermodynamic optimization

    International Nuclear Information System (INIS)

    Phan, Anh Thu; Paek, Min-Kyu; Kang, Youn-Bae

    2014-01-01

    In order to provide an efficient tool to design alloy chemistry and processing conditions for high-strength, lightweight steel, an investigation of the Fe–Al–C ternary system was carried out by experimental phase diagram measurement and a CALPHAD thermodynamic analysis. Discrepancies between previously available experimental results and thermodynamic calculations were identified. The Fe–Al sub-binary system was re-optimized in order to obtain an accurate description of the liquid phase, while Gibbs energies of solid phases were mainly taken from a previous thermodynamic modeling. Phase equilibria among face-centered cubic (fcc)/body-centered cubic (bcc)/graphite/κ-carbide/liquid phases in the Fe–Al–C system in the temperature range from 1000 to 1400 °C were obtained by chemical equilibration followed by quenching, and subsequent composition analysis using electron probe microanalysis/inductively coupled plasma spectroscopy. By merging the revised Fe–Al binary description with existing Fe–C and Al–C binary descriptions, a complete thermodynamic description of the Fe–Al–C system was obtained in the present study. The modified quasi-chemical model in the pair approximation was used to model the liquid phase, while solid solutions were modeled using compound energy formalism. A2/B2 order/disorder transition in the bcc phase was taken into account. Compared with previously known experiments/thermodynamic modeling, a better agreement was obtained in the present study, regarding the stable region of fcc and the solidification thermal peak of a ternary alloy near the liquidus temperature. The obtained thermodynamic description also reproduced various types of experimental data in the Fe–Al–C system such as isothermal sections, vertical sections, liquidus projection, etc. The solidification of various steel grades was predicted and discussed

  1. Quantifying geological uncertainty in metamorphic phase equilibria modelling; a Monte Carlo assessment and implications for tectonic interpretations

    Directory of Open Access Journals (Sweden)

    Richard M. Palin

    2016-07-01

    Full Text Available Pseudosection modelling is rapidly becoming an essential part of a petrologist's toolkit and often forms the basis of interpreting the tectonothermal evolution of a rock sample, outcrop, or geological region. Of the several factors that can affect the accuracy and precision of such calculated phase diagrams, “geological” uncertainty related to natural petrographic variation at the hand sample- and/or thin section-scale is rarely considered. Such uncertainty influences the sample's bulk composition, which is the primary control on its equilibrium phase relationships and thus the interpreted pressure–temperature (P–T conditions of formation. Two case study examples—a garnet–cordierite granofels and a garnet–staurolite–kyanite schist—are used to compare the relative importance that geological uncertainty has on bulk compositions determined via (1 X-ray fluorescence (XRF or (2 point counting techniques. We show that only minor mineralogical variation at the thin-section scale propagates through the phase equilibria modelling procedure and affects the absolute P–T conditions at which key assemblages are stable. Absolute displacements of equilibria can approach ±1 kbar for only a moderate degree of modal proportion uncertainty, thus being essentially similar to the magnitudes reported for analytical uncertainties in conventional thermobarometry. Bulk compositions determined from multiple thin sections of a heterogeneous garnet–staurolite–kyanite schist show a wide range in major-element oxides, owing to notable variation in mineral proportions. Pseudosections constructed for individual point count-derived bulks accurately reproduce this variability on a case-by-case basis, though averaged proportions do not correlate with those calculated at equivalent peak P–T conditions for a whole-rock XRF-derived bulk composition. The main discrepancies relate to varying proportions of matrix phases (primarily mica relative to

  2. Thermodynamic calculation of Al-Gd and Al-Gd-Mg phase equilibria checked by key experiments

    International Nuclear Information System (INIS)

    Groebner, J.; Kevorkov, D.; Schmid-Fetzer, R.

    2001-01-01

    The binary Al-Gd and the ternary Al-Gd-Mg systems were calculated using the Calphad method. It is demonstrated that previous interpretation of ternary liquidus temperatures below 700 C must be related to other phase equilibria. The actual ternary liquidus temperatures are much higher, up to some 600 C above the previous interpretation in literature. They are widely governed by the high-melting compounds Al 2 Gd and Al 3 Gd with liquidus surfaces stretching far into the ternary system. A small number of key experiments in this work confirmed the calculated liquidus temperature and the phase relations. The available experimental data in literature fit excellently with the calculation in the binary Al-Gd system. In the ternary Al-Gd-Mg system, which is shown in several sections of the phase diagram, a good agreement can be observed too, considering the necessary reinterpretation of the liquidus temperatures suggested by Rokhlin et al. Ternary solubilities were not found experimentally. The ternary compound Al 4 GdMg (τ) forms in a ternary peritectic reaction at 761 C. (orig.)

  3. High-Temperature Phase Equilibria of Duplex Stainless Steels Assessed with a Novel In-Situ Neutron Scattering Approach

    Science.gov (United States)

    Pettersson, Niklas; Wessman, Sten; Hertzman, Staffan; Studer, Andrew

    2017-04-01

    Duplex stainless steels are designed to solidify with ferrite as the parent phase, with subsequent austenite formation occurring in the solid state, implying that, thermodynamically, a fully ferritic range should exist at high temperatures. However, computational thermodynamic tools appear currently to overestimate the austenite stability of these systems, and contradictory data exist in the literature. In the present work, the high-temperature phase equilibria of four commercial duplex stainless steel grades, denoted 2304, 2101, 2507, and 3207, with varying alloying levels were assessed by measurements of the austenite-to-ferrite transformation at temperatures approaching 1673 K (1400 °C) using a novel in-situ neutron scattering approach. All grades became fully ferritic at some point during progressive heating. Higher austenite dissolution temperatures were measured for the higher alloyed grades, and for 3207, the temperature range for a single-phase ferritic structure approached zero. The influence of temperatures in the region of austenite dissolution was further evaluated by microstructural characterization using electron backscattered diffraction of isothermally heat-treated and quenched samples. The new experimental data are compared to thermodynamic calculations, and the precision of databases is discussed.

  4. Direct phase coexistence molecular dynamics study of the phase equilibria of the ternary methane-carbon dioxide-water hydrate system.

    Science.gov (United States)

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

    2016-09-14

    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.

  5. Fluid phase equilibria during propylene carbonate synthesis from propylene oxide in carbon dioxide medium

    DEFF Research Database (Denmark)

    Gharnati, Loubna; Musko, Nikolai; Jensen, Anker Degn

    2013-01-01

    -cyclic guanidinium bromide on SBA-15 (HEPCGBr/SBA-15) as catalyst in the absence of any co-catalyst. It was found that the yield was strongly dependent on the amount of CO2 added to the system and that the phase behavior strongly changes along the reaction pathway. The Cubic-Plus-Association (CPA) equation of state...... was used to predict the phase behavior during the reaction and the number and composition of coexisting phases in the multicomponent reaction system were determined. In accordance with the experimental data, the maximum conversion was achieved in the transition region between the two- and the one-phase...... region where a CO2-expanded reactant/product phase (larger volume due to the dissolution of carbon dioxide in the liquid phase) is present. Optimal conditions for performing the reaction have been derived which requires consideration not only of the phase behavior of the starting phase but also...

  6. Experimental (solid + liquid) or (liquid + liquid) phase equilibria of (amine + nitrile) binary mixtures

    International Nuclear Information System (INIS)

    Domanska, Urszula; Marciniak, Malgorzata

    2007-01-01

    (Solid + liquid) phase diagrams have been determined for (hexylamine, or octylamine, or 1,3-diaminopropane + acetonitrile) mixtures. Simple eutectic systems have been observed in these mixtures. (Liquid + liquid) phase diagrams have been determined for (octylamine, or decylamine + propanenitrile, or + butanenitrile) mixtures. Mixtures with propanenitrile and butanenitrile show immiscibility in the liquid phase with an upper critical solution temperature, UCST. (Solid + liquid) phase diagrams have been correlated using NRTL, NRTL 1, Wilson and UNIQUAC equations. (Liquid + liquid) phase diagrams have been correlated using NRTL equation

  7. Experimental study on the phase equilibria of the Ag-Ti system

    International Nuclear Information System (INIS)

    Fu Xiaoliang; Li Changrong; Wang Fuming; Li Mei; Zhang Weijing

    2005-01-01

    The Ag-Ti diffusion couples were prepared by small pure silver plates closely packed in pure titanium powder, sealed in quartz tube, and annealed at 750 deg. C, 980 deg. C, 1100 deg. C and 1200 deg. C, respectively. The phase equilibrium relationship and the conjugate phase compositions in the Ag-Ti system were determined by means of the metallographic microscope and the electron probe microanalysis. Partial liquidus and solidus for the two-phase equilibrium, liquid + (βTi), were obtained. The narrow solution range for the intermediate phase (TiAg) was determined

  8. Oxygen potentials and phase equilibria of the quaternary Y-Ba-Cu-O system in the region involving the YBa2Cu3O7-x phase

    International Nuclear Information System (INIS)

    Fitzner, K.; Musbah, O.; Hsieh Kerchang; Zhang Minxian; Chang, Y.A.

    1993-01-01

    The equilibrium oxygen potentials of four-phase equilibria (counting only the condensed phases) in the CuO-Cu 2 O-BaCuO 2 -Y 2 BaCuO 5 (211)-YBa 2 Cu 3 O 7-x (123) phase region were determined using the following solid-oxide electrolyte e.m.f. cell: Pt10Rh, air (psub(O 2 )=0.21 atm) vertical stroke ZrO 2 +Y 2 O 3 vertical stroke mixtures of oxides, Pt. The oxide mixtures whose oxygen potentials were measured were CuO-Cu 2 O-211-123, CuO-Cu 2 O-BaCuO 2 -123, Cu 2 O-BaCuO 2 -211-123 and CuO-BaCuO 2 -211-123. The phase in some of the mixtures were identified by X-ray diffraction. These data were analyzed and are presented using stability diagrams, i.e., oxygen potential as a function of the reciprocal of the temperature. Extrapolation of these data for the four four-phase equilibra to high temperatures yields a metastable five-phase equilibrium, i.e., 123=CuO+Cu 2 O+BaCuO 2 +211, at ∼1243 K (970 ) and log psub(O 2 ) ∼ -1.21 (psub(O 2 )∼0.062 atm). (orig.)

  9. Modelling the phase equilibria of multicomponent mixtures containing CO2, alkanes, water, and/or alcohols using the quadrupolar CPA equation of state

    DEFF Research Database (Denmark)

    Bjørner, Martin Gamel; Kontogeorgis, Georgios

    2016-01-01

    In this work, a quadrupolar cubic plus association (qCPA) equation of state is evaluated for its ability to predict the phase equilibria of multicomponent mixtures containing CO2 and alkanes, alcohols, and/or water. A single binary interaction parameter is employed in qCPA for all binary combinat...... CPA yields the best results of all the models for the prediction of dew point pressures....

  10. Phase equilibria of binary, ternary and quaternary systems for polymerization/depolymerization of polycarbonate

    NARCIS (Netherlands)

    Margon, V.; Agarwal, U.S.; Peters, C.J.; Wit, de G.; Bailly, C.M.E.; Kasteren, van J.M.N.; Lemstra, P.J.

    2005-01-01

    Vapor–liquid phase equilibrium is studied for the systems composed of phenol, diphenyl carbonate (DPC), bisphenol A (BPA) and CO2. Bubble point pressures and vapor-phase compositions are measured at various temperatures (343.15–473.15 K) for several compositions of the following systems: two binary

  11. Influence of Adsorption and Capillary Pressure on Phase Equilibria Inside Shale Reservoirs

    DEFF Research Database (Denmark)

    Sandoval, Diego R.; Yan, Wei; Michelsen, Michael L.

    2018-01-01

    is moderate in comparison to the that at low pressure and high temperature. The adsorption effects are stronger for the gas bulk phase region, leading to bigger changes in the gas phase composition and the shift of the dew point curve. PVT simulations of two model reservoir fluid systems show significant...... envelope is different. In general, a much shrunk phase envelope with a shifted critical point is observed. The heavier components are preferentially adsorbed in the whole pressure and temperature range studied here. At high pressure and low temperature, the selectivity towards heavier components...

  12. REVIEWS OF TOPICAL PROBLEMS: Order-disorder transformations and phase equilibria in strongly nonstoichiometric compounds

    Science.gov (United States)

    Gusev, Aleksandr I.

    2000-01-01

    Data on order-disorder phase transformations in strongly nonstoichiometric carbides and nitrides MXy (X=C, N) of Group IV and V transition metals at temperatures below 1300-1400 K are reviewed. The order-parameter functional method as applied to atomic and vacancy ordering in strongly nonstoichiometric MXy compounds and to phase equilibrium calculations for M-X systems is discussed. Phase diagram calculations for the Ti-C, Zr-C, Hf-C, V-C, Nb-C, Ta-C, Ti-N, and Ti-B-C systems (with the inclusion of the ordering of nonstoichiometric carbides and nitrides) and those for pseudobinary carbide M(1)C-M(2)C systems are presented. Heat capacity, electrical resistivity and magnetic susceptibility changes at reversible order-disorder phase transformations in nonstoichiometric carbides are considered.

  13. Phase equilibria and thermodynamic properties of high-alloy tool steels : theoretical and experimental approach

    OpenAIRE

    Bratberg, Johan

    2005-01-01

    The recent development of tool steels and high-speed steels has led to a significant increase in alloy additions, such as Co, Cr, Mo, N, V, and W. Knowledge about the phase relations in these multicomponent alloys, that is, the relative stability between different carbides or the solubility of different elements in the carbides and in the matrix phase, is essential for understanding the behaviour of these alloys in heat treatments. This information is also the basis for improving the properti...

  14. Attractive evolutionary equilibria

    NARCIS (Netherlands)

    Joosten, Reinoud A.M.G.; Roorda, Berend

    2011-01-01

    We present attractiveness, a refinement criterion for evolutionary equilibria. Equilibria surviving this criterion are robust to small perturbations of the underlying payoff system or the dynamics at hand. Furthermore, certain attractive equilibria are equivalent to others for certain evolutionary

  15. Phase Equilibria in the Bi-In-Sn-Zn System. Thermal Analysis vs. Calculations

    Directory of Open Access Journals (Sweden)

    Dębski A.

    2017-12-01

    Full Text Available With the use of the differential thermal analysis (DTA, studies of the phase transitions were conducted for 90 of alloys from the quaternary Bi-In-Sn-Zn system and for the constant ratio of Bi:In and Bi:Sn. The studies were conducted for the alloys prepared from the purity metals (Bi, In, Sn, Zn = 99.999 mas. % by way of melting in a graphite crucible in a glove-box filled with Ar, in which the impurities level was less than 0.1 ppm. After melting and thorough mixing, the liquid alloys were poured out into a graphite test mold. The phase transition temperature data obtained from the DTA investigations were next confronted with those determined from the calculations based on the binary and ternary optimized thermodynamic parameters available in the literature. It was found that the experimental and the calculated phase transition temperatures were in good agreement.

  16. Vapor-liquid Phase Equilibria for CO2+Tertpentanol Binary System at Elevated Pressures

    Institute of Scientific and Technical Information of China (English)

    WANG Lin; LUO Jian-cheng; YANG Hao; CHEN Kai-xun

    2011-01-01

    Vapor-liquid phase equilibrium data of tertpentanol in carbon dioxide were measured at temperatures of 313.4,323.4,333.5 and 343.5 K and in the pressure range of 4.56-11.44 MPa.The phase equilibium apparatus used in the work was a variable-volume high-pressure cell.The experimental data were reasonably correlated with Peng-Robinson equation of state(PR-EOS) together with van der Waals-2 two-parameter mixing rules.Henry's Law constants and partial molar volumes of CO2 at infinite dilution were estimated with Krichevsky-Kasarnovsky equation,and Henry's Law constants increase with increasing temperature,however,partial molar volumes of CO2 at infinite dilution are negative whose magnitudes decrease with temperature.Partial molar volumes of CO2 and tertpentanol in liquid phase at equilibrium were calculated.

  17. Coal ash fusion temperatures -- New characterization techniques, and associations with phase equilibria

    Energy Technology Data Exchange (ETDEWEB)

    Wall, T.F.; Gupta, R.P.; Gupta, S. [Univ. of Newcastle, New South Wales (Australia). Dept. of Chemical Engineering; Creelman, R.A. [R.A. Creelman and Associates, Epping, New South Wales (Australia); Coin, C. [ACIRL Ipswich, Booval, Queensland (Australia); Lowe, A. [Pacific Power, Sydney, New South Wales (Australia)

    1996-12-31

    The well-documented shortcomings of the standard technique for estimating the fusion temperature of coal ash are its subjective nature and poor accuracy. Alternative measurements based on the shrinkage and electrical conductivity of heating samples are therefore examined with laboratory ash prepared at about 800 C in crucibles, as well as combustion ash sampled from power stations. Sensitive shrinkage measurements indicate temperatures of rapid change which correspond to the formation of liquid phases that can be identified on ternary phase diagrams. The existence and extent of formation of these phases, as quantified by the magnitude of peaks in the test, provide alternative ash fusion temperatures. The peaks from laboratory ashes and corresponding combustion ashes derived from the same coals show clear differences which may be related to the evaporation of potassium during combustion and the reactions of the mineral residues to form combustion ash.

  18. Phase extraction equilibria in systems rare earth (3) nitrates-ammonium nitrate-water-trialkylmethylammonium nitrate

    International Nuclear Information System (INIS)

    Pyartman, A.K.; Kopyrin, A.A.; Puzikov, E.A.

    1995-01-01

    The distribution of rare earth metals (3) between aqueous and organic phases in the systems rare earth metal (3) (praseodymium-lutetium (3), yttrium (3)) nitrate-ammonium nitrate-water-trialkylmethylammonium (kerosene diluent nitrate has been studied. It is shown that in organic phase di- and trisolvates of metals (3) with tralkylmethylammonium nitrate are formed. The influence of concentration of rare earth metal (3) nitrate and ammonium nitrate on the values of extraction concentrational constants has been ascertained: they decrease with increase in the ordinal number of lanthanide (3). 11 refs., 4 figs. 1 tab

  19. A New Approach to Modeling Densities and Equilibria of Ice and Gas Hydrate Phases

    Science.gov (United States)

    Zyvoloski, G.; Lucia, A.; Lewis, K. C.

    2011-12-01

    The Gibbs-Helmholtz Constrained (GHC) equation is a new cubic equation of state that was recently derived by Lucia (2010) and Lucia et al. (2011) by constraining the energy parameter in the Soave form of the Redlich-Kwong equation to satisfy the Gibbs-Helmholtz equation. The key attributes of the GHC equation are: 1) It is a multi-scale equation because it uses the internal energy of departure, UD, as a natural bridge between the molecular and bulk phase length scales. 2) It does not require acentric factors, volume translation, regression of parameters to experimental data, binary (kij) interaction parameters, or other forms of empirical correlations. 3) It is a predictive equation of state because it uses a database of values of UD determined from NTP Monte Carlo simulations. 4) It can readily account for differences in molecular size and shape. 5) It has been successfully applied to non-electrolyte mixtures as well as weak and strong aqueous electrolyte mixtures over wide ranges of temperature, pressure and composition to predict liquid density and phase equilibrium with up to four phases. 6) It has been extensively validated with experimental data. 7) The AAD% error between predicted and experimental liquid density is 1% while the AAD% error in phase equilibrium predictions is 2.5%. 8) It has been used successfully within the subsurface flow simulation program FEHM. In this work we describe recent extensions of the multi-scale predictive GHC equation to modeling the phase densities and equilibrium behavior of hexagonal ice and gas hydrates. In particular, we show that radial distribution functions, which can be determined by NTP Monte Carlo simulations, can be used to establish correct standard state fugacities of 1h ice and gas hydrates. From this, it is straightforward to determine both the phase density of ice or gas hydrates as well as any equilibrium involving ice and/or hydrate phases. A number of numerical results for mixtures of N2, O2, CH4, CO2, water

  20. Determination of thermodynamic parameters of tautomerization in gas phase by mass spectrometry and DFT calculations: Keto-enol versus nitrile-ketenimine equilibria.

    Science.gov (United States)

    Giussi, Juan M; Gastaca, Belen; Albesa, Alberto; Cortizo, M Susana; Allegretti, Patricia E

    2011-02-01

    The study of tautomerics equilibria is really important because the reactivity of each compound with tautomeric capacity can be determined from the proportion of each tautomer. In the present work the tautomeric equilibria in some γ,δ-unsaturated β-hydroxynitriles and γ,δ-unsaturated β-ketonitriles were studied. The first family of compounds presents two possible theoretical tautomers, nitrile and ketenimine, while the second one presents four possible theoretical tautomers, keto-nitrile, enol (E and Z)-nitrile and keto-ketenimine. The equilibrium in gas phase was studied by gas chromatography-mass spectrometry (GC-MS). Tautomerization enthalpies were calculated by this methodology, and results were compared with those obtained by density functional theory (DFT) calculations, observing a good agreement between them. Nitrile tautomers were favored within the first family of compounds, while keto-nitrile tautomers were favored in the second family. Copyright © 2010 Elsevier B.V. All rights reserved.

  1. Modeling Phase Equilibria for Acid Gas Mixtures using the Cubic-Plus-Association Equation of State. 3. Applications Relevant to Liquid or Supercritical CO2 Transport

    DEFF Research Database (Denmark)

    Tsivintzelis, Ioannis; Ali, Shahid; Kontogeorgis, Georgios

    2014-01-01

    density data for both CO2 and CO2–water and for vapor–liquid equilibrium for mixtures of CO2 with various compounds present in transport systems. In all of these cases we consider various possibilities for modeling CO2 (inert, self-associating using two-, three-, and four sites) and the possibility......The CPA (cubic-plus-association) equation of state is applied in this work to a wide range of systems of relevance to CO2 transport. Both phase equilibria and densities over extensive temperature and pressure ranges are considered. More specifically in this study we first evaluate CPA against......” for applying CPA to acid gas mixtures. The overall conclusion is that CPA performs satisfactorily; the model in most cases correlates well binary data and predicts with good accuracy multicomponent vapor–liquid equilibria. Among the various approaches investigated, the best ones are when cross association...

  2. Transport and Phase Equilibria Properties for Steam Flooding of Heavy Oils

    Energy Technology Data Exchange (ETDEWEB)

    Gabitto, Jorge; Barrufet, Maria

    2002-11-20

    The objectives of this research included experimental determination and rigorous modeling and computation of phase equilibrium diagrams, volumetric, and transport properties of hydrocarbon/CO2/water mixtures at pressures and temperatures typical of steam injection processes for thermal recovery of heavy oils.

  3. Thermal analysis and prediction of phase equilibria in ternary Pb-Zn-Ag System

    Czech Academy of Sciences Publication Activity Database

    Živković, D.; Minić, D.; Manasijević, D.; Šesták, Jaroslav; Živković, Ž.

    2011-01-01

    Roč. 47, č. 1 (2011), 23-30 ISSN 1450-5339 Institutional research plan: CEZ:AV0Z10100521 Keywords : Pb-Zn-Ag system * thermal analysis * phase equilibrium Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.317, year: 2011

  4. Microstructure and phase equilibria in the Ni-Al-W system

    Czech Academy of Sciences Publication Activity Database

    Popovič, J.; Brož, P.; Buršík, Jiří

    2008-01-01

    Roč. 16, č. 7 (2008), s. 884-888 ISSN 0966-9795 R&D Projects: GA ČR(CZ) GA106/07/1078 Institutional research plan: CEZ:AV0Z20410507 Keywords : nickel aluminides * heat treatment * phase diagram Subject RIV: BJ - Thermodynamics Impact factor: 2.034, year: 2008

  5. Phase equilibria in the ternary In–Ni–Sn system at 700 °C

    Czech Academy of Sciences Publication Activity Database

    Schmetterer, C.; Zemanová, Adéla; Flandorfer, H.; Kroupa, Aleš; Ipser, H.

    2013-01-01

    Roč. 35, APR (2013), s. 90-97 ISSN 0966-9795 R&D Projects: GA MŠk(CZ) OC08053 Institutional support: RVO:68081723 Keywords : intermatallics * miscellaneous * phase diagrams Subject RIV: BJ - Thermodynamics Impact factor: 2.119, year: 2013

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

    DEFF Research Database (Denmark)

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

    2010-01-01

    using the TIP4P/ice potential and a united-atom Lennard-Jones potential. respectively. The equilibrium calculation method for this system has three components, (i) thermodynamic integration from a supercritical ideal gas to obtain the fluid-phase chemical potentials. (ii) calculation of the chemical...

  7. The phase equilibria in the Ti-Cu-Y ternary system at 773 K

    Energy Technology Data Exchange (ETDEWEB)

    Hu Zhaohua [Key Laboratory of Nonferrous Metal Materials and New Processing Technology, Ministry of Education, Guangxi University, Nanning, Guangxi 530004 (China); Zhan Yongzhong, E-mail: zyzmatres@yahoo.com.c [Key Laboratory of Nonferrous Metal Materials and New Processing Technology, Ministry of Education, Guangxi University, Nanning, Guangxi 530004 (China); She Jia; Zhang Guanghua; Peng Dan [Key Laboratory of Nonferrous Metal Materials and New Processing Technology, Ministry of Education, Guangxi University, Nanning, Guangxi 530004 (China)

    2009-10-19

    Physical-chemical analysis apparatuses, including X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and differential thermal analysis (DTA) were employed in constructing the isothermal section of the Ti-Cu-Y system at 773 K. The existences of 10 binary compounds, Ti{sub 2}Cu, TiCu, Ti{sub 3}Cu{sub 4}, Ti{sub 2}Cu{sub 3}, TiCu{sub 4}, Cu{sub 6}Y, Cu{sub 4}Y, Cu{sub 7}Y{sub 2}, Cu{sub 2}Y and CuY were confirmed. The isothermal section consists of 13 single-phase regions, 23 binary phase regions and 11 ternary phase regions. No ternary compound is found in this work. Except the binary compounds YCu{sub 6} and TiCu{sub 4} show homogeneity regions less than 1.5 at.%, none of the other phases in this system reveals a remarkable homogeneity range at 773 K.

  8. Theory of phase equilibria and critical mixing points in binary lipid bilayers

    DEFF Research Database (Denmark)

    Risbo, Jens; Sperotto, Maria Maddalena; Mouritsen, Ole G.

    1995-01-01

    the transition is discussed in terms of the molecular properties of the lipid acyl chains. The results of the numerical model study are expected to have consequences for the interpretation of experimental measurements on lipid bilayer systems in terms of phase diagrams. (C) 1995 American Institute of Physics....

  9. Application of ab initio electronic structure calculations for prediction of phase equilibria in superaustenitic steels

    Czech Academy of Sciences Publication Activity Database

    Vřešťál, J.; Kroupa, Aleš; Šob, Mojmír

    2006-01-01

    Roč. 38, č. 11 (2006), s. 298-302 ISSN 0927-0256 R&D Projects: GA ČR(CZ) GA106/03/1354; GA AV ČR(CZ) IBS2041105 Institutional research plan: CEZ:AV0Z20410507 Keywords : electronic structure * Phase diagrams * Steel Subject RIV: BJ - Thermodynamics Impact factor: 1.104, year: 2006

  10. Synthetic methods in phase equilibria: A new apparatus and error analysis of the method

    DEFF Research Database (Denmark)

    Fonseca, José; von Solms, Nicolas

    2014-01-01

    of the equipment was confirmed through several tests, including measurements along the three phase co-existence line for the system ethane + methanol, the study of the solubility of methane in water, and of carbon dioxide in water. An analysis regarding the application of the synthetic isothermal method...

  11. The system Ta-V-Si: Crystal structure and phase equilibria

    Czech Academy of Sciences Publication Activity Database

    Khan, A.U.; Brož, P.; Niu, H.Y.; Buršík, Jiří; Grytsiv, A.; Chen, X.-Q.; Giester, G.; Rogl, P.

    2012-01-01

    Roč. 187, - (2012), s. 114-123 ISSN 0022-4596 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068 Institutional research plan: CEZ:AV0Z20410507 Keywords : ternary alloy system * microstructure * phase diagram Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.040, year: 2012

  12. The phase equilibria of multicomponent gas hydrate in methanol/ethylene glycol solution based formation water

    International Nuclear Information System (INIS)

    Xu, Shurui; Fan, Shuanshi; Yao, Haiyuan; Wang, Yanhong; Lang, Xuemei; Lv, Pingping; Fang, Songtian

    2017-01-01

    Highlights: • The equilibrium data in THI solution based formation water is first investigated. • The 0.55 mass fraction concentration of EG 0.55 mass fraction fills the vacancy of this area. • The testing pressure range from 4.22 MPa to 34.72 MPa was rare in published data. - Abstract: In this paper, the three-phase coexistence points are generated for multicomponent gas hydrate in methanol (MeOH) solution for (0.05, 0.10, 0.15, and 0.35) mass fraction and ethylene glycol (EG) solution for (0.05, 0.10, 0.15, 0.35, 0.40 and 0.55) mass fraction. The phase equilibrium curves of different system were obtained by an isochoric pressure-search method on high pressure apparatus. The phase equilibrium regions of multicomponent gas hydrate were measured using the same composition of natural gas distributed in the South China Sea. And the different concentration solutions were prepared based formation water. The experimental data were measured in a wide range temperature from 267.74 to 298.53 K and a wide range pressure from 4.22 MPa to 34.72 MPa. The results showed that the hydrate phase equilibrium curves shifted to the inhibition region in accordance with the increased inhibitor concentration. In addition, the equilibrium temperature would decrease about 2.7 K when the concentration of MeOH increased 0.05 mass fraction. Besides, the suppression temperature was 1.25 K with the 0.05 mass fraction increase of EG concentration in the range of 0.05 mass fraction to 0.15 mass fraction. While in high EG concentration region, the suppression temperature was 3.3 K with the same increase of EG concentration (0.05 mass fraction).

  13. The phase equilibria and thermal stability of the long-period stacking ordered phase in the Mg–Cu–Y system

    International Nuclear Information System (INIS)

    Jiang, Min; Su, Xiulan; Li, Hongxiao; Ren, Yuping; Qin, Gaowu

    2014-01-01

    Highlights: • 14H LPSO structure has been confirmed to be stable in the Mg–Cu–Y system. • Partial isothermal sections of the Mg–Cu–Y system from 300 to 450 °C have been established. • Reaction L + α-Mg ↔ 14H + Mg 2 Cu has been determined in the Mg–Cu–Y system. • The thermal stability of the 14H phase in the Mg–Cu–Y system has been well studied. - Abstract: Phase equilibria in the Mg-rich Mg–Cu–Y system at 300, 400 and 450 °C have been experimentally investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), electron probe micro-analyzer (EPMA) and transmission electron microscope (TEM). The results show that a long-period stacking ordered (LPSO) phase 14H is stable in the Mg–Cu–Y system, which is the only one ternary intermetallic compound that gets a thermodynamic equilibrium with the a-Mg phase. The equilibrium 14H phase has a very limited solid solution range, and can be nearly regarded as a ternary stoichiometric compound with a formulae as Mg 91 Cu 4 Y 5 . The thermal stability of the 14H phase in the Mg–Cu–Y system has been well studied, which shows that the 14H phase disappears varying from 442 °C to 490 °C depending on the alloy composition. The isothermal sections of the Mg-rich Mg–Cu–Y system at 300, 400 and 450 °C have been finally established, and moreover, a quasi-peritectic reaction L + α-Mg ↔ 14H + Mg 2 Cu has been determined occurring at 442 °C with an estimated liquid composition of Mg 77 Cu 18 Y 5

  14. Evolution of the Campanian Ignimbrite Magmatic System I: Constraints on Compositional Zonation and Eruption Probability Imposed By Phase Equilibria

    Science.gov (United States)

    Fowler, S.; Spera, F.; Bohrson, W.; Belkin, H.; Devivo, B.

    2005-12-01

    The eruption and deposition of the ~39.3 ka Campanian Ignimbrite (CI), a large volume (~200 km3 DRE) trachytic to phonolitic ignimbrite, is the dominant event in the history of the Campi Flegrei volcanic field near Naples, Italy. In an effort to comprehend its petrological evolution, we have conducted ~~110 MELTS (Ghiorso, 1997) phase equilibria simulations of the major element evolution of parental CI magma. The goals of this work are to approximate oxygen fugacity (fO2), initial dissolved water content and pressure at which isobaric closed system fractional crystallization of parental melt most accurately captures the observed liquid line of descent and to study the implications of heat extraction from parental CI magma with respect to the origin of compositional zonation and the probability of explosive eruption. Although the CI magma body did not evolve as a perfectly closed system, this assumption allows quantitative insight into magma-host rock mass exchange using trace element and isotopic data (see companion contribution by Bohrson et al.). The parental melt composition was reconstructed using data for melt inclusions trapped within CI clinopyroxene phenocrysts reported by Webster et al. (2003), while allowing for reaction between parental melt and clinopyroxene host. The inferred parental melt is a basaltic trachyandesite. The search space for pressure, (fO2) and initial dissolved H2O was 0.1-0.5 in 0.05 GPa increments, QFM-1 to QFM+3 and 1, 2 and 3 wt. % H2O, respectively. The criteria used to judge the quality of a simulation include correspondence of the MELTS prediction with CI liquid and phenocryst compositions. Results indicate that a good first-order model involves evolution from a basaltic trachyandesite parent by isobaric (~0.15 GPa) crystal fractionation initially containing ~3 wt% dissolved H2O along the QFM+1 buffer. H2O first saturates at 1127°C at 0.15 GPa when the dissolved water content is ~4 wt %. A striking result is the

  15. Phase equilibria of binary mixtures by molecular simulation and cubic equations of state

    Directory of Open Access Journals (Sweden)

    Cabral V.F.

    2001-01-01

    Full Text Available Molecular simulation data were used to study the performance of equations of state (EoS and combining rules usually employed in thermodynamic property calculations. The Monte Carlo method and the Gibbs ensemble technique were used for determining composition and densities of vapor and liquid phases in equilibrium for binary mixtures of Lennard-Jones fluids. Simulation results are compared to data in the literature and to those calculated by the t-PR-LJ EoS. The use of adequate combining rules has been shown to be very important for the satisfactory representation of molecular simulation data.

  16. Phase Equilibria and Ionic Solvation in the Lithium Tetrafluoroborate-Dimethylsulfoxide System

    Science.gov (United States)

    Gafurov, M. M.; Kirillov, S. A.; Gorobets, M. I.; Rabadanov, K. Sh.; Ataev, M. B.; Tretyakov, D. O.; Aydemirov, K. M.

    2015-01-01

    The phase diagram and electrical conductivity isotherms for the lithium tetrafluoroborate (LiBF4)-dimethylsulfoxide (DMSO) system and Raman spectra of DMSO and the LiBF4-DMSO solution were studied. Spectroscopic signatures of a H-bond between DMSO and BF4 - ions were found. The bonds of Li+ ions to the solvent were stronger than the bonds in DMSO dimers because formation of the solvate destroyed dimeric DMSO molecules. The τω values for DMSO molecules in the Li+-ion solvate shell of the LiBF4-DMSO system were similar to those for associated solvent molecules.

  17. Phase equilibria in a system of aqueous arginine with an octane solution of sulfonic acid

    Science.gov (United States)

    Kuvaeva, Z. I.; Koval'chuk, I. V.; Vodop'yanova, L. A.; Soldatov, V. S.

    2013-05-01

    The extraction of arginine (Arg) from aqueous salt (0.1 M NaCl) solutions with a sulfo extractant in a wide range of pH values and amino acid concentrations was studied. The 0.1 M solution of dinonylnaphthalenesulfonic acid (HD) in octane was used as an extractant. The degree of extraction was found to be high at pH 0.8-9.0. This can be explained by the effect of additional intermolecular interactions in the extractant phase involving the guanidine group of Arg.

  18. Phase equilibria in the system Nd(PO3)3 - KPO3

    International Nuclear Information System (INIS)

    Znamierowska, T.; Mizer, D.

    2002-01-01

    The system Nd(PO 3 ) 3 - KPO 3 has been investigated by differential thermal analysis (during heating), thermogravimetric analysis, mass spectrometry, Raman spectroscopy and X-ray powder diffraction and its phase diagram was proposed. It was discovered that initial metaphosphates react at a 1:1 molar ratio forming intermediate compound KNd(PO 3 ) 4 . It was found that it melts incongruently at 854 o C giving Nd(po)3) 3 and a liquid rich in KPO 3 . Phosphate KNd(PO 3 ) 4 is stable down to room temperature and does not show any polymorphic transitions. (author)

  19. Calculation of phase equilibria in the Na2SO4-K2SO4-Cs2SO4-H2O system at 25 deg C

    International Nuclear Information System (INIS)

    Filippov, V.K.; Kalinkin, A.M.; Vasin, S.K.

    1990-01-01

    Calculation results of solubility diagram and water activity in saturated solutions of Na 2 SO 4 -K 2 SO 4 -Cs 2 SO 4 -H 2 O system at 25 deg C are presented. It is shown that for the calculation of quaternary systems one can use the Pitzer equations. Solubility diagram for the system studied is plotted and data on composition and water activity of solutions saturated by two or three solid phases are given. Classification of nonvariant equilibria from the viewpoint of isomorphism of solubility and fusibility diagrams permits to depict the direction of phase processes during isothermal evaporation of water

  20. Phase equilibria in the system As2-O5 - SrO

    International Nuclear Information System (INIS)

    Kasenov, B.K.; Ashlyaeva, I.V.

    1993-01-01

    T-x phase state diagram of As 2 O 5 -SrO system was investigated by the methods of physicochemical analysis. It was established that incongruently melting Sr(AsO 3 ) 2 (t mel 900 deg C), Sr 2 As 2 O 4 (t mel = 1140 deg C), Sr 4 As 2 O 9 (t mel = 1390 deg C) and congruently melting at 1635 deg C Sr 3 (AsO 4 ) 2 formed in the system. Eutectic points were revealed in the system: As 2 O 5 -Sr(AsO 3 ) 2 (15.0 mol % SrO, 700 deg C) and Sr 3 (AsO 4 ) 2 -Sr 4 As 2 O 9 (78 mol % SrO, 1370 deg C)

  1. Phase equilibria in the system Li2O - MoO3 - Sc2O3

    International Nuclear Information System (INIS)

    Safonov, V.V.; Chaban, N.G.; Porotnikov, N.V.

    1984-01-01

    Using the methods of DTA and X-ray phase analysis, interaction of components in the system Li 2 O-MoO 3 -Sc 2 O 3 in concentration range, adjacent to the vertex of MoO 3 , has been studied. Projection of the Li 2 MoO 4 -MoO 3 -Sc 2 (MoO 4 ) 3 system liquidus on concentrational triangle of the compositions Li 2 O-MoO 3 -Sc 2 O 3 , which consists of the fields of primary separation of Li 2 MoO 4 , Li 2 Mo 5 O 17 , Li 2 Mo 4 O 13 , MoO 3 , Sc 2 (MoO 4 ) 3 , Li 3 Sc(MoO 4 ) 3 and LiSc(MoO 4 ) 2 , is built

  2. Phase equilibria for mixtures containing nonionic surfactant systems: Modeling and experiments

    International Nuclear Information System (INIS)

    Shin, Moon Sam; Kim, Hwayong

    2008-01-01

    Surfactants are important materials with numerous applications in the cosmetic, pharmaceutical, and food industries due to inter-associating and intra-associating bond. We present a lattice fluid equation-of-state that combines the quasi-chemical nonrandom lattice fluid model with Veytsman statistics for (intra + inter) molecular association to calculate phase behavior for mixtures containing nonionic surfactants. We also measured binary (vapor + liquid) equilibrium data for {2-butoxyethanol (C 4 E 1 ) + n-hexane} and {2-butoxyethanol (C 4 E 1 ) + n-heptane} systems at temperatures ranging from (303.15 to 323.15) K. A static apparatus was used in this study. The presented equation-of-state correlated well with the measured and published data for mixtures containing nonionic surfactant systems

  3. Thermal analysis, phase equilibria, and superconducting properties in magnesium boride and carbon doped magnesium boride

    Science.gov (United States)

    Bohnenstiehl, Scot David

    In this work, the low temperature synthesis of MgB2 from Mg/B and MgH2/B powder mixtures was studied using Differential Scanning Calorimetry (DSC). For the Mg/B powder mixture, two exothermic reaction events were observed and the first reaction event was initiated by the decomposition of Mg(OH)2 on the surface of the magnesium powder. For the MgH 2/B powder mixture, there was an endothermic event at ˜375 °C (the decomposition of MgH2 into H2 and Mg) and an exothermic event ˜600 °C (the reaction of Mg and B). The Kissinger analysis method was used to estimate the apparent activation energy of the Mg and B reaction using DSC data with different furnace ramp rates. The limitations of MgB2 low temperature synthesis led to the development of a high pressure induction furnace that was constructed using a pressure vessel and an induction heating power supply. The purpose was to not only synthesize more homogeneous MgB2 samples, but also to determine whether MgB2 melts congruently or incongruently. A custom implementation of the Smith Thermal Analysis method was developed and tested on aluminum and AlB2, the closest analogue to MgB2. Measurements on MgB2 powder and a high purity Mg/B elemental mixture confirmed that MgB2 melts incongruently and decomposes into a liquid and MgB4 at ˜1445 °C at 10 MPa via peritectic decomposition. Another measurement using a Mg/B elemental mixture with impure boron suggested that ˜0.7 wt% carbon impurity in the boron raised the incongruent melting temperature to ˜1490-1500 °C. Lastly, the solubility limit for carbon in MgB2 was studied by making samples from B4C and Mg at 1530 °C, 1600 °C and 1700 °C in the high pressure furnace. All three samples had three phases: Mg, MgB2C2, and carbon doped MgB2. The MgB 2C2 and carbon doped MgB2 grain size increased with temperature and the 1700 °C sample had needle-like grains for both phases. The presence of the ternary phase, MgB2C2, suggested that the maximum doping limit for carbon in

  4. Phase transitions on (liquid + liquid) equilibria for (water + 1-methylnaphthalene + light aromatic hydrocarbon) ternary systems at T = (563, 573, and 583) K

    International Nuclear Information System (INIS)

    Togo, Masaki; Inamori, Yoshiki; Shimoyama, Yusuke

    2012-01-01

    Highlights: ► Mixtures of (water + 1-methylnaphthalene + light aromatic hydrocarbon) are focused. ► Phase transition pressures on (liquid + liquid) equilibria were measured. ► Effects of aromatic hydrocarbons on phase transition pressure are investigated. ► Phase transition pressures are discussed using dielectric constants of hydrocarbons. - Abstract: Phase transitions for (water + 1-methylnaphthalene + light aromatic hydrocarbon) ternary systems are observed at their (liquid + liquid) equilibria at T = (563, 573, and 583) K and (8.6 to 25.0) MPa. The phase transition pressures at T = (563, 573, and 583) K were measured for the five species of light aromatic hydrocarbons, o-, m-, p-xylenes, ethylbenzene, and mesitylene. The measurements of the phase transition pressures were carried out by changing the feed mole fraction of water and 1-methylnaphthalene in water free, respectively. Effects of the feed mole fraction of water on the phase transition pressures are very small. Increasing the feed mole fraction of 1-methylnaphthalene results in decreasing the phase transition pressures at constant temperature. The slopes depending on the feed mole fraction for 1-methylnaphthalene at the phase transition pressures are decreased with increasing temperature for (water + 1-methylnaphthalene + p-xylene), (water + 1-methylnaphthalene + o-xylene), and (water + 1-methylnaphthalene + mesitylene) systems. For xylene isomers, the highest and lowest of the phase transition pressures are obtained in the case of p- and o-xylenes, respectively. The phase transition pressures for ethylbenzene are lower than those in the case of p-xylene. The similar phase transition pressures are given for p-xylene and mesitylene.

  5. Phase Equilibria of a S- and C-Poor Lunar Core

    Science.gov (United States)

    Righter, K.; Pando, K.; Go, B. M.; Danielson, L. R.; Habermann, M.

    2016-01-01

    The composition of the lunar core can have a large impact on its thermal evolution, possible early dynamo creation, and physical state. Geochemical measurements have placed better constraints on the S and C content of the lunar mantle. In this study we have carried out phase equilibrium studies of geochemically plausible S- and C-poor lunar core compositions in the Fe-Ni-S-C system, and apply them to the early history of the Moon. We chose two bulk core compositions, with differing S and C content based on geochemical analyses of S and C trapped melts in Apollo samples, and on the partitioning of S and C between metal and silicate. This approach allowed calculation of core S and C contents - 90% Fe, 9% Ni, 0.5% C, and 0.375% S by weight; a second composition contained 1% each of S and C. Experiments were carried out from 1473K to 1973K and 1 GPa to 5 GPa, in piston cylinder and multi- anvil apparatuses. Combination of the thermal model of with our results, shows that a solid inner core (and therefore initiation of a dynamo) may have been possible in the earliest history of the Moon (approximately 4.2 Ga ago), in agreement with. Thus a volatile poor lunar core may explain the thermal and magnetic history of the Moon.

  6. Phase equilibria, leaching characteristics and ceramic processing of SYNROC D formulations for US defense wastes

    International Nuclear Information System (INIS)

    Newkirk, H.; Ryerson, F.; Coles, D.; Hoenig, C.; Rozsa, R.; Rossington, C.; Bazan, F.; Tewhey, J.

    1980-01-01

    The assemblage of coexisting phases in SYNROC D is perovskite, zirconolite, nepheline and spinel. Cesium from the supernate is to be immobilized in hollandite. In the current processing scheme, presynthesized granules of hollandite are added to calcined SYNROC D powders prior to hot procesing or sintering. The disposition of inert and radwaste components of Savannah River Plant (SRP) wastes in SYNROC D formulations has been determined by means of optical microscopy, XRD, XRF, SEM, STEM, electron microprobe analysis and autoradiography. A summary of results is presented. Leaching studies of SYNROC D have been done by means of static, high temperature experiments and continuous-flow experiments. The data reported are from high-temperature experiments (distilled water, powdered sample, 150 0 C, one day). The elements reported are the only ones observed in the leachate. Analysis was done by means of XRF. The flowsheet which depicts the current experimental methods that are being employed at LLNL to produce SYNROC D samples containing presynthesized Cs-bearing hollandite is presented. The starting material for SYNROC D (high Fe, high Al and composite compositions) is simulated sludge obtained in 55 gallon quantities from Southwestern Chemical Corporation. Hot pressing temperatures for SYNROC D are 1000 to 1150 0 C. Hot pressing temperatures for hollandite are 1200 to 1400 0 C

  7. Phase equilibria, crystal chemistry, electronic structure and physical properties of Ag-Ba-Ge clathrates

    Energy Technology Data Exchange (ETDEWEB)

    Zeiringer, I.; Chen Mingxing [Institute of Physical Chemistry, University of Vienna, Waehringerstr. 42, 1090 Wien (Austria); Bednar, I.; Royanian, E.; Bauer, E. [Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Wien (Austria); Podloucky, R.; Grytsiv, A. [Institute of Physical Chemistry, University of Vienna, Waehringerstr. 42, 1090 Wien (Austria); Rogl, P., E-mail: peter.franz.rogl@univie.ac.at [Institute of Physical Chemistry, University of Vienna, Waehringerstr. 42, 1090 Wien (Austria); Effenberger, H. [Institute of Mineralogy and Crystallography, University of Vienna, A-1090 Wien (Austria)

    2011-04-15

    In the Ag-Ba-Ge system the clathrate type-{Iota} solid solution, Ba{sub 8}Ag{sub x}Ge{sub 46-x-y{open_square}y}, extends at 800 deg. C from binary Ba{sub 8}Ge{sub 43{open_square}3} ({open_square} is a vacancy) to Ba{sub 8}Ag{sub 5.3}Ge{sub 40.7}. For the clathrate phase (1 {<=} x {<=} 5.3) the cubic space group Pm3-bar n was established by X-ray powder diffraction and confirmed by X-ray single-crystal analyses of the samples Ba{sub 8}Ag{sub 2.3}Ge{sub 41.9{open_square}1.8} and Ba{sub 8}Ag{sub 4.4}Ge{sub 41.3{open_square}0.3}. Increasing the concentration of Ag causes the lattice parameters of the solid solution to increase linearly from a value of a = 1.0656 (x = 0, y = 3) to a = 1.0842 (x = 4.8, y = 0) nm. Site preference determination using X-ray refinement reveals that Ag atoms preferentially occupy the 6d site randomly mixed with Ge and vacancies, which become filled in the compound Ba{sub 8}Ag{sub 4.8}Ge{sub 41.2} when the Ag content increases. At 600 {sup o}C the phase region of the clathrate solution Ba{sub 8}Ag{sub x}Ge{sub 46-x-y{open_square}y} becomes separated from the Ba-Ge boundary and extends from 6.6 to 9.8 at.% Ag. The compound Ba{sub 6}Ge{sub 25} (clathrate type-{Iota}X) dissolves at 800 {sup o}C a maximum of 1.5 at.% Ag. The homogeneity regions of the two ternary compounds BaAg{sub 2-x}Ge{sub 2+x} (ThCr{sub 2}Si{sub 2}-type, 0.2 {<=} x {<=} 0.7) and Ba(Ag{sub 1-x}Ge{sub x}){sub 2} (AlB{sub 2}-type, 0.65 {<=} x {<=} 0.75) were established at 800 deg. C. Studies of transport properties for the series of Ba{sub 8}Ag{sub x}Ge{sub 46-x-y{open_square}y} compounds evidenced that electrons are the predominant charge carriers with the Fermi energy close to a gap. Its position can be fine-tuned by the substitution of Ge by Ag atoms and by mechanical processing of the starting material, Ba{sub 8}Ge{sub 43}. The proximity of the electronic structure at Fermi energy of Ba{sub 8}Ag{sub x}Ge{sub 46-x-y{open_square}y} to a gap is also corroborated by density

  8. Phase equilibria and homogeneity range of the high temperature superconducting compound (Bi,Pb)2+xSr2Ca2Cu3O10+δ

    International Nuclear Information System (INIS)

    Kaesche, S.

    1995-01-01

    For the superconducting cuprates (Bi,Pb) 2+x Sr 2 Ca 2 Cu 3 O 10+y phase equilibria, the homogeneity region, and the phase formation has been studied in the temperture range 800 to 890 C. Sintered samples were prepared by a solid state reaction starting from Bi 2 O 3 , PbO, CuO and carbonates CaCO 3 and SrCO 3 in a three-stage calcination process. For the phase identification polarization microscopy, X-ray diffraction and susceptibility measurements have been applied. Multi-phase regions were determined in the cross section of the quasi-ternary system (Bi,Pb) 2 O 3 -SrO-CaO-CuO with constant Bi/(Bi+Pb) ratio 0.84 taking into account the 2223-phase. The homogeneity region was determined as function of Sr, Ca, Bi and Pb concentration. Its maximum size was found at 850 C

  9. Experimental Phase Equilibria Studies of the Pb-Fe-O System in Air, in Equilibrium with Metallic Lead and at Intermediate Oxygen Potentials

    Science.gov (United States)

    Shevchenko, M.; Jak, E.

    2017-12-01

    The phase equilibria information on the Pb-Fe-O system is of practical importance for the improvement of the existing thermodynamic database of lead-containing slag systems (Pb-Zn-Fe-Cu-Si-Ca-Al-Mg-O). Phase equilibria of the Pb-Fe-O system have been investigated: (a) in air at temperatures between 1053 K and 1373 K (780 °C and 1100 °C); (b) in equilibrium with metallic lead at temperatures between 1053 K and 1373 K (780 °C and 1100 °C); and (c) at intermediate oxidation conditions for the liquid slag in equilibrium with two solids (spinel + magnetoplumbite), at temperatures between 1093 K and 1373 K (820 °C and 1100 °C). The high-temperature equilibration/quenching/electron probe X-ray microanalysis technique has been used to accurately determine the compositions of the phases in equilibrium in the system. The Pb and Fe concentrations in the phases were determined directly; preliminary thermodynamic modeling with FactSage was used to estimate the ferrous-to-ferric ratios and to present the results in the ternary diagram.

  10. Phase equilibria in the MgMoO4-Ln2(MoO4)3 (Ln=La,Gd) systems

    International Nuclear Information System (INIS)

    Fedorov, N.F.; Ipatov, V.V.; Kvyatkovskij, O.V.

    1980-01-01

    Phase equilibria in the MgMoO 4 -Ln 2 (MoO 4 ) 3 systems (Ln=La, Gd) have been studied by static and dynamic methods of the physico-chemical analysis, using differential thermal, visual-polythermal, crystal-optical, X-ray phase, and infrared spectroscopic methods, and their phase diagrams have been constructed. Phase equilibria in the systems studied are characterized by limited solubility of components in the liquid state, formation of solid solutions on the base of α- and β-forms of Gd 2 (MoO 4 ) 3 . Eutectics in the MgMoO 4 -Ln 2 (MoO 4 ) 3 (Ln=La, Gd) systems corresponds to the composition of 71 mode % La 2 (MoO 4 ) 3 -29 mole % MgMoO 4 , tsub(melt)--935+-5 deg C and 57 mole % Gd 2 (MoO 4 ) 3 -43 mole % MgMoO 4 , tsub(melt)=1020+-5 deg C. The region of glass formation has been established [ru

  11. Random-lattice models and simulation algorithms for the phase equilibria in two-dimensional condensed systems of particles with coupled internal and translational degrees of freedom

    DEFF Research Database (Denmark)

    Nielsen, Morten; Miao, Ling; Ipsen, John Hjorth

    1996-01-01

    In this work we concentrate on phase equilibria in two-dimensional condensed systems of particles where both translational and internal degrees of freedom are present and coupled through microscopic interactions, with a focus on the manner of the macroscopic coupling between the two types...... where the spin degrees of freedom are slaved by the translational degrees of freedom and develop a first-order singularity in the order-disorder transition that accompanies the lattice-melting transition. The internal degeneracy of the spin states in model III implies that the spin order...

  12. Phase equilibria at low temperature for light hydrocarbons-methanol-water-acid gases mixtures: measurements and modelling; Equilibres de phases a basse temperature de systemes complexes CO{sub 2} - hydrocarbures legers - methanol - eau: mesures et modelisation

    Energy Technology Data Exchange (ETDEWEB)

    Ruffine, L.

    2005-10-15

    The need to develop and improve natural gas treatment processes is real. The petroleum industry usually uses separation processes which require phase equilibrium phenomena. Yet, the complexity of the phase equilibria involved results in a lack of data, which in turn limits the development of thermodynamic models. The first part of this work is devoted to experimental investigations for systems containing light hydrocarbons, methanol, water and acid gases. We present a new apparatus that was developed to measure vapor-liquid and vapor-liquid-liquid equilibria. It allowed us to obtain new phase composition data for the methanol-ethane binary system and different mixtures, and also to determine a part of the three phases equilibrium envelope of the same systems. In the second part of this work, we have developed a thermodynamic model based on the CPA equation of state. This choice may be justified by the presence of associating components like methanol, hydrogen sulfide and water in the systems. Such model is necessary for the design of gas treatment plants. Our model provides good results for phase equilibrium calculations for binaries systems without binary interaction parameter in many cases, and describes correctly the vapour-liquid and vapor-liquid-liquid equilibria for complex mixtures. (author)

  13. Phase equilibria modelling and zircon dating for Precambrian metapelites from Xinghuadukou Group in Lvlin Forest of Erguna Massif, NE China

    Science.gov (United States)

    Xu, Jiulei; Zheng, Changqing; Tajcmanova, Lucie; Zhong, Xin; Xu, Xuechun; Han, Xiaomeng; Wang, Zhaoyuan

    2017-04-01

    Xinghuadukou Group, the basement metamorphic complex of Erguna Massif in NE China, is considered to be Mesoproterozoic with Sm-Nd age of 1157±32 Ma. However, the new zircon data from these metamorphic supracrustal rocks in Lvlin Forest show that they formed in Neoproterozoic with the age of 800 Ma. Old zircon age with 2.5 Ga, 2.0 Ga and 1.8 Ga, indicate that the Erguna Massif had an affinity to both Columbia and Rodinia continents. Furthermore, we also present 500 Ma metamorphic age in micashists and 500 Ma age of adjacent granitoids that might have thermally influenced its surrounding. No detailed studies have been undertaken on the metamorphic evolution of the Xinghuadukou Complex. The typical paragneissic mineral assemblage of garnet sillimanite mica schist is Grt+Sil+Bt+Mus+Qtz±Kfs. (Zhou et al., 2011) proposed that the Xinghuadukou Complex appears to have undergone similar granulite facies metamorphic conditions based on the similarity of mineral assemblages to the Mashan Complex in the Jiamusi Massif, NE China. However, the new phase equilibria modelling result shows that these rocks are high amphibolite facies product with 650℃. We can easily find K-feldspar formed by partial melting due to the consuming of muscovite. Also the remaining muscovite is directly connected with a fluid channel in thin sections which indicate that the remaining muscovite formed from retrograde with the existence of fluid. The zoned garnet has low MgO and high CaO content in rims and high MgO and low CaO content in core. It seems that this garnet has high pressure and low temperature (HP-LT) in rims and low pressure and high temperature (LP-HT) in core which would point to an anti-clockwise metamorphic evolution. Zhou, J.B., Wilde, S.A., Zhang, X.Z., Zhao, G.C., Liu, F.L., Qiao, D.W., Ren, S.M. and Liu, J.H., 2011b. A> 1300km late Pan-African metamorphic belt in NE China: new evidence from the Xing'an block and its tectonic implications. Tectonophysics, 509(3): 280-292.

  14. Equilibres de phases dans les systèmes fluides petroliers-eau Phase Equilibria in Oil-Water Systems

    Directory of Open Access Journals (Sweden)

    Peneloux A.

    2006-11-01

    Full Text Available Nous présentons quelques résultats obtenus à partir du logiciel FHYD qui permet le traitement des mélanges eau-fluides pétroliers, avec la détermination de la nature des phases (huile-gaz-eau-hydrate thermodynamiquement stables dans des conditions données de température et de pression, ainsi que de la quantité, de la composition de ces différentes phases et de leurs propriétés. Ce logiciel permet le tracé automatique des diagrammes de phases et nous présentons des exemples, depuis les systèmes binaires (eau-éthane, ternaires (eau-méthane-propane jusqu'aux fluides les plus complexes. La présence de sels (chlorure de sodium dissous est envisagée, ainsi que le calcul des conditions de dépôt du sel solide. Des exemples de problèmes pétroliers sont cités (gaz de séparateur saturé en eau, huile saturée en eau dans les conditions de gisement, huile en présence d'eau salée. Les estimations sur les quantités d'hydrate formées et leurs compositions sont comparées à des données expérimentales et aux résultats obtenus par d'autres logiciels. Le programme FHYD pourrait permettre une représentation plus réaliste de l'évolution des fluides pétroliers et des propriétés de transport de leurs différentes phases dans les modèles de simulation des conduites polyphasiques. This article presents a selection of results obtained with the FHYD program. This software allows simulation of mixtures composed of petroleum fluids and water, with determination of the nature of thermodynamically stable phases (oil-gas-water-hydrate under given conditions of temperature and pressure, along with the quantity, composition and properties of these different phases. Additionally, the program can automatically produce phase diagrams. Several examples of these have been included here, ranging from binary systems (water-ethane and ternary systems (water-methane-propane to the most complex petroleum fluids. The presence of dissolved salts

  15. Deformation and microstructure of rutile

    International Nuclear Information System (INIS)

    Blanchin, M.G.; Bursill, L.A.; Lafage, C.

    1989-01-01

    Studies of the mechanical properties of rutiles are described, in particular the behaviour of the elastic limit under compression with respect to variations in temperature (pure rutile), intrinsic non-stoichiometry (pure rutile reduced under low oxygen pressure) and extrinsic non-stoichiometry (rutile doped with chromia and alumina). A wide range of values is obtained, which may be understood in terms of the interaction of dislocations belonging to the slip systems {101} and {110} with impurities, non-stoichiometric small and extended defects and precipitates. Transmission electron microscopy at medium resolution as well as high resolution electron microscopy have been used to relate mechanical behaviour with microstructure. 43 refs., 18 figs., 2 tabs

  16. 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

    2012-04-01

    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.

  17. Rutile nanopowders for pigment production: Formation mechanism and particle size prediction

    Science.gov (United States)

    Zhang, Wu; Tang, Hongxin

    2018-01-01

    Formation mechanism and particle size prediction of rutile nanoparticles for pigment production were investigated. Anatase nanoparticles were observed by oriented attachment with parallel lattice fringe spaces of 0.2419 nm. Upon increasing the calcination temperature, the (1 1 0) plane of rutile was gradually observed, suggesting that the anatase (1 0 3) planes undergo internal structural rearrangement of oxygen and titanium ions into rutile phase due to ionic diffusion. Backpropagation neural network was used to predict particle size of rutile nanopowders, the prediction errors were all smaller than 2%, providing an efficient method to control particle size in pigment production.

  18. Attractive evolutionary equilibria

    OpenAIRE

    Roorda, Berend; Joosten, Reinoud

    2011-01-01

    We present attractiveness, a refinement criterion for evolutionary equilibria. Equilibria surviving this criterion are robust to small perturbations of the underlying payoff system or the dynamics at hand. Furthermore, certain attractive equilibria are equivalent to others for certain evolutionary dynamics. For instance, each attractive evolutionarily stable strategy is an attractive evolutionarily stable equilibrium for certain barycentric ray-projection dynamics, and vice versa.

  19. Spinel + quartz-bearing ultrahigh-temperature granulites from Xumayao, Inner Mongolia Suture Zone, North China Craton: Petrology, phase equilibria and counterclockwise p-T path

    Directory of Open Access Journals (Sweden)

    Huatian Zhang

    2012-09-01

    Our phase equilibria modeling indicates two main stages during the metamorphic evolution of these rocks: 1 near-isobaric cooling from 975 °C to 875 °C around 8 kbar, represented by the formation of garnet porphyroblasts from spinel and quartz; and 2 cooling and decompression from 850 °C, 8 kbar to below 750 °C, 6.5 kbar, represented by the break-down of garnet. The spinel + quartz assemblage is considered to have been stable at peak metamorphism, formed through the break-down of cordierite, indicating a near isothermal compression process. Our study confirms the regional extent of UHT metamorphism within the IMSZ associated with the Paleoproterozoic subduction-collision process.

  20. Modeling phase equilibria of alkanols with the simplified PC-SAFT equation of state and generalized pure compound parameters

    DEFF Research Database (Denmark)

    Grenner, Andreas; Kontogeorgis, Georgios; von Solms, Nicolas

    2007-01-01

    The simplified PC-SAFT equation of state has been applied to liquid-liquid, vapor-liquid and solid-liquid equilibria for mixtures containing 1-or 2-alkanols with alkanes, aromatic hydrocarbons, CO2 and water. For the alkanols we use generalized pure compound parameters. This means that two...... of the physical pure compound parameters, in (segment number) and or (segment diameter), are obtained from linear extrapolations, since m and m sigma(3), increase linearly with respect to the molar mass, and moreover, the two association parameters (association energy and association volume) were assumed...... to be constant for all alkanols. Only the dispersion energy is fitted to experimental data. Thus it is possible to estimate parameters for several 1-and 2-alkanols. The final aim is to develop a group contribution approach for PC-SAFT which is suitable for complex compounds, considering that the motivation...

  1. Evaluation of the polysubstituted pyridinium ionic liquid [hmmpy][Ntf2] as a suitable solvent for desulfurization: Phase equilibria

    International Nuclear Information System (INIS)

    Arce, Alberto; Francisco, Maria; Soto, Ana

    2010-01-01

    Suitability of a pyridinium ionic liquid as a solvent in desulfurization has been analyzed. (Liquid + liquid) equilibria for ternary systems composed by 1-hexyl-3,5-dimethyl pyridinium {bis[trifluoromethylsulfonyl]imide, thiophene, and three hydrocarbons representative of fuel (n-heptane, 2,2,4 trimethylpentane, and toluene) have been determined at T = 298.15 K and atmospheric pressure. High solubility of thiophene in the ionic liquid and also of toluene have been found, being this solvent practically immiscible with 2,2,4 trimethylpentane and heptane. Equilibrium data of these systems have been well correlated with UNIQUAC equations finding the highest deviations for the ternary system involving toluene. NRTL model drove to worse results being considered as not suitable model to correlate the experimental results.

  2. Development of long-lived radionuclides partitioning technology - Experimental/theoretical study of phase equilibria for multicomponent multiphase systems

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chul Soo; Lee, Se Il; Sim, Yeon Sik; Park, Sung Bin; Yang, Sung Oh; Park, Ji Yong [Korea University, Seoul (Korea, Republic of)

    1995-08-01

    In various partitioning processes, rare earth elements and actinide elements are separated from other elements in the first stage. They are then separated into rare earth groups and actinde groups. The first stage is accomplished by solvent extraction using DEHPA, by precipitation using oxalic= acid, or by cation exchange. The second stage is carried out by selective back-extraction or by selective elution using DTPA. In these processes the equilibria is governed by the concentrations of nitric acid, of solvents, and of precipitants among others. In this study various distribution coefficients in partitioning processes were experimentally determined. And thermodynamic models were proposed to calculate distribution coefficients with experimentally determined equilibrium constants. 32 refs., 11 tabs., 23 figs. (author)

  3. Thermophysical properties and phase equilibria study of the binary systems {l_brace}N-hexylquinolinium bis(trifluoromethylsulfonyl)imide + aromatic hydrocarbons, or an alcohol{r_brace}

    Energy Technology Data Exchange (ETDEWEB)

    Domanska, Urszula, E-mail: ula@ch.pw.edu.p [Department of Physical Chemistry, Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw (Poland); Thermodynamic Research Unit, School of Chemical Engineering, University of KwaZulu-Natal, Howard College Campus, King George V Avenue, Durban 4001 (South Africa); Zawadzki, Maciej [Department of Physical Chemistry, Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw (Poland); Zwolinska, Magdalena [Department of Ergonomics, Laboratory of Thermal Loads, Central Institute for Labour Protection-National Research Institute, Czerniakowska 16, 00-701 Warsaw (Poland)

    2011-05-15

    Research highlights: We synthesized new ionic liquid, [HQuin][NTf{sub 2}] with low viscosity, and low density. We found high heat capacity, high enthalpy of melting and low melting temperature. HQuin][NTf{sub 2}] is proposed for possible use in the phase change materials (PCM). We examine phase equilibrium changes, SLE and LLE with hydrocarbons and alcohols. [HQuin][NTf{sub 2}] may be proposed as entrainer for the separation proceses. - Abstract: The new quinolinium ionic liquid has been synthesised as a continuation of our work with quinolinium-based ionic liquids (ILs). The work includes specific basic characterisation of synthesized compounds: N-hexylquinolinium bromide, [HQuin][Br] and N-hexylquinolinium bis{l_brace}(trifluoromethyl)sulfonyl{r_brace}imide [HQuin][NTf{sub 2}] by NMR spectra, elementary analysis and water content. The basic thermal properties of the pure [HQuin][NTf{sub 2}] i.e. melting and glass-transition temperatures, the enthalpy of fusion as well as heat capacity have been measured using a differential scanning microcalorimetry technique (DSC) and thermal analysis instrument (TA). Densities and viscosities were determined as a function of temperature. Phase equilibria for the binary systems: {l_brace}[HQuin][NTf{sub 2}]) + aromatic hydrocarbon (benzene, or toluene, or ethylbenzene, or n-propylbenzene), or an alcohol (1-butanol, or 1-hexanol, or 1-octanol, or 1-decanol){r_brace} have been determined at ambient pressure. A dynamic method was used over a broad range of mole fractions and temperatures from (270 to 320) K. For all the binary systems with benzene and alkylbenzenes, the eutectic diagrams were observed with immiscibility gap in the liquid phase beginning from (0.13 to 0.28) mole fraction of the IL with very high an upper critical solution temperature (UCST). For mixtures with alcohols, the complete miscibility was observed for 1-butanol and immiscibility with UCST in the liquid phase for the remaining alcohols. The typical

  4. Study of phase equilibria in function of temperature in UO2-PuO2-Pu2O3 system for nuclear ceramics with high plutonium contents

    International Nuclear Information System (INIS)

    Truphemus, Thibaut

    2013-01-01

    In the UO 2 -PuO 2 -Pu 2 O 3 section, a monophasic (U 1-y ,Pu y )O 2-x domain is stable for y≤0,20 at 25 C and up to solid-liquid equilibrium. At higher Pu content, phase equilibria are more unclear with a phase separation process. The main objective of this work consisted in upgrading the representation of this system for 0,15≤y≤0,65 and 25≤T(C)≤1500. At 25 C, a miscibility gap composed by two different (U 1-y ,Pu y )O 2-x phases has been observed for y≤0,45, with one very closed to stoichiometric state (Oxygen/Metal=2) and one other very reduced. For the first time, a triphasic domain has been characterized at higher Pu contents, with two (U 1-y ,Pu y )O 2-x phases near y=0,45 and one (U 1-y ,Pu y ) 2 O 3 phase with a low U content inside. Concerning the study in function of temperature, we have demonstrated that phase separation temperature increase when Pu content grows. Several representations have been established. At 200 C, the representation is closed to that at 25 C. At 400 C, the phase separation have been specified at a lower Pu content than that of literature: y=0,35. At 600 C, our results have clarified the section, until then very unclear, with a phase separation appearing at y=0,60.The microstructural analysis has clearly demonstrated the significant impact of the phase separation on the material. Indeed many cracks have been observed in our samples, and quantity of these defects increases when Pu content grows. (author) [fr

  5. The Al-rich region of the Al-Mn-Ni alloy system. Part II. Phase equilibria at 620-1000 oC

    International Nuclear Information System (INIS)

    Balanetskyy, S.; Meisterernst, G.; Grushko, B.; Feuerbacher, M.

    2011-01-01

    Research highlights: → Phase equilibria in the Al-rich region of the Al-Mn-Ni alloy system were studied at 1000, 950, 850, 750, 700, 645 and 620 deg. C by means of SEM, TEM, powder XRD and DTA. → Three ternary thermodynamically stable intermetallics, the φ-phase (Al 5 Co 2 -type, hP26, P63/mmc; a = 0.76632(16), c = 0.78296(15) nm), the κ-phase (κ-Al 14.4 Cr 3.4 Ni l.1 -type, hP227, P63/m; a = 1.7625(10), c = 1.2516(10) nm), and the O-phase (O-Al 77 Cr 14 Pd 9 -type, Pmmn, oP650,: a = 2.3316(16), b = 1.2424(15), c = 3.2648(14) nm), as well as three ternary metastable phases, the decagonal D 3 -phase with periodicity about 1.25 nm, the Al 9 (Mn,Ni) 2 -phase (Al 9 Co 2 -type, P1121/a, mP22; a = 0.8585(16), b = 0.6269(9), c = 0.6205(11) nm, β = 95.34(10) o ) and the O 1 -phase (basecentered orthorhombic, a ∼ 23.8, b ∼ 12.4, c ∼ 32.2 nm) were revealed. → The existence of a thermodynamically stable R-phase of stoichiometry Al 60 Mn 11 Ni 4 , reported earlier in literature, was not confirmed in the present study. - Abstract: Phase equilibria in the Al-rich region of the Al-Mn-Ni alloy system were studied at 1000, 950, 850, 750, 700, 645 and 620 o C. Three ternary thermodynamically stable intermetallics, the φ-phase (Al 5 Co 2 -type, hP26, P6 3 /mmc; a = 0.76632(16), c = 0.78296(15) nm), the κ-phase (κ-Al 14.4 Cr 3.4 Ni l.1 -type, hP227, P6 3 /m; a = 1.7625(10), c = 1.2516(10) nm), and the O-phase (O-Al 77 Cr 14 Pd 9 -type, Pmmn, oP650,: a = 2.3316(16), b = 1.2424(15), c = 3.2648(14) nm), as well as three ternary metastable phases, the decagonal D 3 -phase with periodicity about 1.25 nm, the Al 9 (Mn,Ni) 2 -phase (Al 9 Co 2 -type, P112 1 /a, mP22; a = 0.8585(16), b = 0.6269(9), c = 0.6205(11) nm, β = 95.34(10) o ) and the O 1 -phase (base-centered orthorhombic, a ∼ 23.8, b ∼ 12.4, c ∼ 32.2 nm) were revealed. Their physicochemical behaviour in the Al-Mn-Ni alloy system was studied.

  6. Formation of rutile fasciculate zone induced by sunlight irradiation at room temperature and its hemocompatibility

    International Nuclear Information System (INIS)

    Zhang, Xuan-Hui; Zheng, Xiang; Cheng, Yuan; Li, Guo-Hua; Chen, Xiao-Ping; Zheng, Jian-Hui

    2013-01-01

    The fasciculate zone of phase pure rutile was fabricated under sunlight irradiation at room temperature, using titanium tetrachloride as a sole precursor. The crystal phase, morphology and microstructure, and optical absorption behavior of the samples were characterized by X-ray Diffraction, High-Resolution Transmission Electron Microscope (HRTEM) and UV–vis Diffuse Reflectance Spectra (DRS), respectively. XRD results show that the crystal phase of the sample is composed of rutile only, and a lattice distortion displays in the crystallite of the sample. HRTEM results show that the morphology of rutile particle is fasciculate zone constituted of nanoparticles with a diameter of 4–7 nm, and these particles grow one by one and step by step. The pattern of the selected area electron diffraction of the sample is Kikuchi type, which can be attributed to the predominant orientation growth of rutile nanoparticles along [001] induced by sunlight irradiation. DRS results show that the absorption threshold of the sample is 415 nm, corresponding to the band gap energy of 2.99 eV, which is lower than the band gap energy of rutile, 3.03 eV. Blood compatibility measurement shows that the sample has no remarkable effect on hemolytic and coagulation activity. The percent hemolysis of red blood cells is less than 5% even treated with a big dosage of the fasciculate rutile and under UV irradiation, and there are no obvious changes of plasma recalcification time after the rutile treatment. Thus, the novel structure of rutile fasciculate has low potential toxicity for blood and is hemocompatibility safe. Highlights: • A novel approach to fabricate the fasciculate zone of phase pure rutile • The fasciculate grows from a particle to nanorod and to fasciculate, step by step. • A preferred orientation growth induced by sunlight irradiation in the fasciculate • The rutile fasciculate is low toxicity for blood and is hemocompatibility safe

  7. The heat capacity of a natural monticellite and phase equilibria in the system CaO-MgO-SiO2-CO2

    Science.gov (United States)

    Sharp, Z.D.; Essene, E.J.; Anovitz, Lawrence M.; Metz, G.W.; Westrum, E.F.; Hemingway, B.S.; Valley, J.W.

    1986-01-01

    The heat capacity of a natural monticellite (Ca1.00Mg.09Fe.91Mn.01Si0.99O3.99) measured between 9.6 and 343 K using intermittent-heating, adiabatic calorimetry yields Cp0(298) and S2980 of 123.64 ?? 0.18 and 109.44 ?? 0.16 J ?? mol-1 K-1 respectively. Extrapolation of this entropy value to end-member monticellite results in an S0298 = 108.1 ?? 0.2 J ?? mol-1 K-1. High-temperature heat-capacity data were measured between 340-1000 K with a differential scanning calorimeter. The high-temperature data were combined with the 290-350 K adiabatic values, extrapolated to 1700 K, and integrated to yield the following entropy equation for end-member monticellite (298-1700 K): ST0(J ?? mol-1 K-1) = S2980 + 164.79 In T + 15.337 ?? 10-3 T + 22.791 ?? 105 T-2 - 968.94. Phase equilibria in the CaO-MgO-SiO2 system were calculated from 973 to 1673 K and 0 to 12 kbar with these new data combined with existing data for akermanite (Ak), diopside (Di), forsterite (Fo), merwinite (Me) and wollastonite (Wo). The location of the calculated reactions involving the phases Mo and Fo is affected by their mutual solid solution. A best fit of the thermodynamically generated curves to all experiments is made when the S0298 of Me is 250.2 J ?? mol-1 K-1 less than the measured value of 253.2 J ?? mol-1 K-1. A best fit to the reversals for the solid-solid and decarbonation reactions in the CaO-MgO-SiO2-CO2 system was obtained with the ??G0298 (kJ ?? mole-1) for the phases Ak(-3667), Di(-3025), Fo(-2051), Me(-4317) and Mo(-2133). The two invariant points - Wo and -Fo for the solid-solid reactions are located at 1008 ?? 5 K and 6.3 ?? 0.1 kbar, and 1361 ?? 10 K and 10.2 ?? 0.2 kbar respectively. The location of the thermodynamically generated curves is in excellent agreement with most experimental data on decarbonation equilibria involving these phases. ?? 1986.

  8. Phase equilibria among α-Fe(Al, Cr, Ti), liquid and TiC and the formation of TiC in Fe3Al-based alloys

    International Nuclear Information System (INIS)

    Kobayashi, Satoru; Schneider, Andre; Zaefferer, Stefan; Frommeyer, Georg; Raabe, Dierk

    2005-01-01

    In the context of the development of high-strength Fe 3 Al-based alloys, phase equilibria among α-Fe(Al, Cr, Ti), liquid and TiC phases in the Fe-Al-Cr-Ti-C quinary system and the formation of TiC were determined. A pseudo-eutectic trough (L α + L + TiC) exists at 1470 deg C at around Fe-26Al-5Cr-2Ti-1.7C on the vertical section between Fe-26Al-5Cr (α) and Ti-46C (TiC) in at.%. Large faceted TiC precipitates form from the melt after the formation of primary α phase even in hypoeutectic alloys. The TiC formation is thought to be due to the composition change of the liquid towards the hypereutectic compositions by solidification of the primary α. In order to remove the faceted TiC, which are unfavourable for strengthening the material, two different processing routes have been successfully tested: (i) solidification with an increased rate to reduce the composition variation of the liquid during solidification, and (ii) unidirectional solidification to separate the light TiC precipitates from the melt

  9. Phase Equilibria of the Ternary Sn-Pb-Co System at 250°C and Interfacial Reactions of Co with Sn-Pb Alloys

    Science.gov (United States)

    Wang, Chao-hong; Kuo, Chun-yi; Yang, Nian-cih

    2015-11-01

    The isothermal section of the ternary Sn-Pb-Co system at 250°C was experimentally determined through a series of the equilibrated Sn-Pb-Co alloys of various compositions. The equilibrium phases were identified on the basis of compositional analysis. For the Sn-Co intermetallic compounds (IMCs), CoSn3, CoSn2, CoSn and Co3Sn2, the Pb solubility was very limited. There exist five tie-triangle regions. The Co-Pb system involves one monotectic reaction, so the phase separation of liquid alloys near the Co-Pb side occurred prior to solidification. The immiscibility field was also determined. Additionally, interfacial reactions between Co and Sn-Pb alloys were conducted. The reaction phase for the Sn-48 at.%Pb and Sn-58 at.%Pb at 250°C was CoSn3 and CoSn2, respectively. Both of them were simultaneously formed in the Sn-53 at.%Pb/Co. The formed IMCs were closely associated to the phase equilibria relationship of the liquid-CoSn3-CoSn2 tie-triangle. Furthermore, with increasing temperatures, the phase formed in equilibrium with Sn-37 wt.%Pb was found to transit from CoSn3 to CoSn2 at 275°C. We propose a simple method of examining the phase transition temperature in the interfacial reactions to determine the boundaries of the liquid-CoSn3-CoSn2 tie-triangles at different temperatures.

  10. The experimental investigation of phase equilibria in the Al-rich corner within the ternary Al–Mn–Be system

    Energy Technology Data Exchange (ETDEWEB)

    Zupanič, Franc, E-mail: franc.zupanic@um.si [University of Maribor, Faculty of Mechanical Engineering, Smetanova ulica 17, SI-2000 Maribor (Slovenia); Markoli, Boštjan; Naglič, Iztok [University of Ljubljana, Faculty of Natural Sciences and Technologies, Askerceva 12, Ljubljana SI-1000 (Slovenia); Bončina, Tonica [University of Maribor, Faculty of Mechanical Engineering, Smetanova ulica 17, SI-2000 Maribor (Slovenia)

    2013-09-05

    Highlights: •We investigated the constitution of the Al-rich corner of the Al–Mn–Be system. •Be{sub 4}AlMn is a thermodynamically stable phase in the Al-corner of the Al–Mn–Be system. •The T-phase (Al{sub 15}Mn{sub 3}Be{sub 2}) is not a stable phase in the Al-corner at 600 °C. •The λ-Al{sub 4}Mn phase is a stable phase in the Al-corner at 600 °C. •T-phase is a stable phase at 750 °C. -- Abstract: This work investigated the constitution of the Al-rich corner within the ternary Al–Mn–Be phase diagram using SEM + EDS, AES, XRD and DSC. With respect to the results, an isothermal cross-section at 600 °C was established, as well as a prediction of the apparent liquidus projection in the Al-corner. Be{sub 4}AlMn is a thermodynamically stable phase in the Al-rich corner of the ternary phase diagram. The other ternary T-phase, usually designated as Al{sub 15}Mn{sub 3}Be{sub 2}, formed during solidification in alloys with Be:Mn atomic ratios of less than 4:1, and having more than 1.5 at.% Mn. This phase is not a stable phase in the Al-rich corner at 600 °C. In contrast, the λ-Al{sub 4}Mn phase is a stable one. The T-phase is stable over a rather large part of the phase diagram at least within a temperature range close to 750 °C, where it is in equilibrium with the Al-rich liquid phase, and Be{sub 4}AlMn.

  11. Some stable hydromagnetic equilibria

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, J L; Oberman, C R; Kulsrud, R M; Frieman, E A [Project Matterhorn, Princeton University, Princeton, NJ (United States)

    1958-07-01

    We have been able to find and investigate the properties of equilibria which are hydromagnetically stable. These equilibria can be obtained, for example, by wrapping conductors helically around the stellarator tube. Systems with I = 3 or 4 are indicated to be optimum for stability purposes. In some cases an admixture of I = 2 fields can be advantageous for achieving equilibrium. (author)

  12. An energy stable evolution method for simulating two-phase equilibria of multi-component fluids at constant moles, volume and temperature

    KAUST Repository

    Kou, Jisheng

    2016-02-25

    In this paper, we propose an energy-stable evolution method for the calculation of the phase equilibria under given volume, temperature, and moles (VT-flash). An evolution model for describing the dynamics of two-phase fluid system is based on Fick’s law of diffusion for multi-component fluids and the Peng-Robinson equation of state. The mobility is obtained from diffusion coefficients by relating the gradient of chemical potential to the gradient of molar density. The evolution equation for moles of each component is derived using the discretization of diffusion equations, while the volume evolution equation is constructed based on the mechanical mechanism and the Peng-Robinson equation of state. It is proven that the proposed evolution system can well model the VT-flash problem, and moreover, it possesses the property of total energy decay. By using the Euler time scheme to discretize this evolution system, we develop an energy stable algorithm with an adaptive choice strategy of time steps, which allows us to calculate the suitable time step size to guarantee the physical properties of moles and volumes, including positivity, maximum limits, and correct definition of the Helmhotz free energy function. The proposed evolution method is also proven to be energy-stable under the proposed time step choice. Numerical examples are tested to demonstrate efficiency and robustness of the proposed method.

  13. A stable algorithm for calculating phase equilibria with capillarity at specified moles, volume and temperature using a dynamic model

    KAUST Repository

    Kou, Jisheng; Sun, Shuyu

    2017-01-01

    Capillary pressure can significantly affect the phase properties and flow of liquid-gas fluids in porous media, and thus, the phase equilibrium calculation incorporating capillary pressure is crucial to simulate such problems accurately. Recently

  14. Phase equilibria, crystal structure and properties of complex oxides in the Nd{sub 2}O{sub 3}–SrO–CoO system

    Energy Technology Data Exchange (ETDEWEB)

    Aksenova, T.V.; Efimova, T.G. [Department of Physical and Inorganic Chemistry, Institute of Natural Science and Mathematics, Ural Federal University, Lenin av., 51, Yekaterinburg 620000 (Russian Federation); Lebedev, O.I. [Laboratoire CRISMAT, ENSICAEN UMR6508, 6 Bd Maréchal Juin, Cedex 4, Caen 14050 (France); Elkalashy, Sh.I.; Urusova, A.S. [Department of Physical and Inorganic Chemistry, Institute of Natural Science and Mathematics, Ural Federal University, Lenin av., 51, Yekaterinburg 620000 (Russian Federation); Cherepanov, V.A., E-mail: v.a.cherepanov@urfu.ru [Department of Physical and Inorganic Chemistry, Institute of Natural Science and Mathematics, Ural Federal University, Lenin av., 51, Yekaterinburg 620000 (Russian Federation)

    2017-04-15

    The phase equilibria in the ½Nd{sub 2}O{sub 3}–SrO–CoO system were systematically studied at 1373 K in air. The intermediate phases formed in the ½Nd{sub 2}O{sub 3}–SrO–CoO system at 1373 K in air are: Nd{sub 1-x}Sr{sub x}CoO{sub 3-δ} (0.0≤x≤0.5 with orthorhombic structure, sp. gr. Pbnm and 0.6≤x≤0.95 whose structure was detected as cubic according to XRD sp. gr. Pm3m, but shown to be tetragonal by TEM due to the oxygen vacancy ordering), Nd{sub 2-y}Sr{sub y}CoO{sub 4-δ} (0.6≤y≤1.1 with tetragonal K{sub 2}NiF{sub 4}-type structure, sp. gr. I4/mmm) and Nd{sub 2-z}Sr{sub z}O{sub 3} (0.0≤z≤0.15 with hexagonal structure, sp. gr. P-3m1). The unit cell parameters for the single phase samples were refined by the Rietveld analysis. The changes of oxygen content in Nd{sub 1-x}Sr{sub x}CoO{sub 3-δ} (0.6≤x≤0.95) and Ruddlesden-Popper oxide Nd{sub 2-y}Sr{sub y}CoO{sub 4-δ} were examined by TGA. All were found to be oxygen deficient phases. High-temperature dilatometry allows calculating the thermal expansion coefficient and evaluating the chemical expansion coefficient at high temperature. The projection of isothermal-isobaric phase diagram for the Nd–Sr–Co–O system at 1373 K in air to the compositional triangle of metallic components has been constructed. The phase equilibria in the studied Nd–Sr–Co–O system were compared to La–Sr–Co–O and Nd–M–Co–O (M=Ca and Ba). - Graphical abstract: Crystal structure of vacancy ordered supercell for Nd{sub 0.2}Sr{sub 0.8}CoO{sub 3-δ} and projection of phase diagram for the Nd–Sr–Co–O system onto the triangle edge of metallic components at 1373 K in air. - Highlights: • The diagram for the Nd–Sr–Co–O system at 1373 K in air has been constructed. • The crystal structure of Nd{sub 1-x}Sr{sub x}CoO{sub 3-δ} and Nd{sub 2-y}Sr{sub y}CoO{sub 4±δ} was refined. • The formation of superstructure due to the oxygen vacancy ordering was proved. • The changes of oxygen

  15. Computation of liquid-liquid equilibria and phase stabilities: implications for RH-dependent gas/particle partitioning of organic-inorganic aerosols

    Directory of Open Access Journals (Sweden)

    A. Zuend

    2010-08-01

    Full Text Available Semivolatile organic and inorganic aerosol species partition between the gas and aerosol particle phases to maintain thermodynamic equilibrium. Liquid-liquid phase separation into an organic-rich and an aqueous electrolyte phase can occur in the aerosol as a result of the salting-out effect. Such liquid-liquid equilibria (LLE affect the gas/particle partitioning of the different semivolatile compounds and might significantly alter both particle mass and composition as compared to a one-phase particle. We present a new liquid-liquid equilibrium and gas/particle partitioning model, using as a basis the group-contribution model AIOMFAC (Zuend et al., 2008. This model allows the reliable computation of the liquid-liquid coexistence curve (binodal, corresponding tie-lines, the limit of stability/metastability (spinodal, and further thermodynamic properties of multicomponent systems. Calculations for ternary and multicomponent alcohol/polyol-water-salt mixtures suggest that LLE are a prevalent feature of organic-inorganic aerosol systems. A six-component polyol-water-ammonium sulphate system is used to simulate effects of relative humidity (RH and the presence of liquid-liquid phase separation on the gas/particle partitioning. RH, salt concentration, and hydrophilicity (water-solubility are identified as key features in defining the region of a miscibility gap and govern the extent to which compound partitioning is affected by changes in RH. The model predicts that liquid-liquid phase separation can lead to either an increase or decrease in total particulate mass, depending on the overall composition of a system and the particle water content, which is related to the hydrophilicity of the different organic and inorganic compounds. Neglecting non-ideality and liquid-liquid phase separations by assuming an ideal mixture leads to an overestimation of the total particulate mass by up to 30% for the composition and RH range considered in the six

  16. A stable algorithm for calculating phase equilibria with capillarity at specified moles, volume and temperature using a dynamic model

    KAUST Repository

    Kou, Jisheng

    2017-09-30

    Capillary pressure can significantly affect the phase properties and flow of liquid-gas fluids in porous media, and thus, the phase equilibrium calculation incorporating capillary pressure is crucial to simulate such problems accurately. Recently, the phase equilibrium calculation at specified moles, volume and temperature (NVT-flash) becomes an attractive issue. In this paper, capillarity is incorporated into the phase equilibrium calculation at specified moles, volume and temperature. A dynamical model for such problem is developed for the first time by using the laws of thermodynamics and Onsager\\'s reciprocal principle. This model consists of the evolutionary equations for moles and volume, and it can characterize the evolutionary process from a non-equilibrium state to an equilibrium state in the presence of capillarity effect at specified moles, volume and temperature. The phase equilibrium equations are naturally derived. To simulate the proposed dynamical model efficiently, we adopt the convex-concave splitting of the total Helmholtz energy, and propose a thermodynamically stable numerical algorithm, which is proved to preserve the second law of thermodynamics at the discrete level. Using the thermodynamical relations, we derive a phase stability condition with capillarity effect at specified moles, volume and temperature. Moreover, we propose a stable numerical algorithm for the phase stability testing, which can provide the feasible initial conditions. The performance of the proposed methods in predicting phase properties under capillarity effect is demonstrated on various cases of pure substance and mixture systems.

  17. Phase equilibria of microemulsion forming system n-decyl-(beta)-D-glucopyranoside/water/n-octane/1-butanol

    DEFF Research Database (Denmark)

    Kahl, Heike; Quitzsch, Konrad; Stenby, Erling Halfdan

    1997-01-01

    of multicomponent system is the coexistence of a highly structural liquid phase enriched with amphiphilic compounds and an excess water or an excess oil phase or both of them. The phase behaviour was studied experimentally by use of turbidity titration and HPLC measurements and theoretically by application...... of the UNIQUAC-equation and the UNIFAC-method. The UNIFAC-method is able to describe the phase behaviour in the quaternary system qualitatively, without fitting parameters. However, by applying the UNIQUAC-method, with adjustable parameters, it was only possible to model the ternary subsystems. The modelling......A systematic investigation of the phase behaviour involving microemulsions is presented with respect to experimental and calculated data for the four-component system n-decyl-(beta)-D-glucopyranoside/water/n-octane/1-butanol and its corresponding ternaries at 25°C. The main feature of this kind...

  18. Phase equilibria in the KFeS2-Fe-S system at 300-600 °C and bartonite stability

    Science.gov (United States)

    Osadchii, Valentin O.; Voronin, Mikhail V.; Baranov, Alexander V.

    2018-05-01

    The article deals with phase relations in the KFeS2-Fe-S system studied by the dry synthesis method in the range of 300-600 °C and at a pressure of 1 bar. At the temperature below 513 ± 3 °C, pyrite coexists with rasvumite and there are pyrite-rasvumite-KFeS2 and pyrite-rasvumite-pyrrhotite equilibria established. Above 513 ± 3 °C pyrite and rasvumite react to form KFeS2 and pyrrhotite, limiting the pyrite-rasvumite association to temperatures below this in nature. The experiments also outline the compositional stability range of the copper-free analog of murunskite (K x Fe2- y S2) and suggest that mineral called bartonite is not stable in the Cl-free system, at least at atmospheric pressure and the temperature in the experiments. Chlorbartonite could be easily produced after adding KCl in the experiment. Possible parageneses in the quaternary K-Fe-S-Cl system were described based on the data obtained in this research and found in the previous studies. The factors affecting the formation of potassium-iron sulfides in nature were discussed.

  19. Learning efficient correlated equilibria

    KAUST Repository

    Borowski, Holly P.; Marden, Jason R.; Shamma, Jeff S.

    2014-01-01

    The majority of distributed learning literature focuses on convergence to Nash equilibria. Correlated equilibria, on the other hand, can often characterize more efficient collective behavior than even the best Nash equilibrium. However, there are no existing distributed learning algorithms that converge to specific correlated equilibria. In this paper, we provide one such algorithm which guarantees that the agents' collective joint strategy will constitute an efficient correlated equilibrium with high probability. The key to attaining efficient correlated behavior through distributed learning involves incorporating a common random signal into the learning environment.

  20. Learning efficient correlated equilibria

    KAUST Repository

    Borowski, Holly P.

    2014-12-15

    The majority of distributed learning literature focuses on convergence to Nash equilibria. Correlated equilibria, on the other hand, can often characterize more efficient collective behavior than even the best Nash equilibrium. However, there are no existing distributed learning algorithms that converge to specific correlated equilibria. In this paper, we provide one such algorithm which guarantees that the agents\\' collective joint strategy will constitute an efficient correlated equilibrium with high probability. The key to attaining efficient correlated behavior through distributed learning involves incorporating a common random signal into the learning environment.

  1. Phase equilibria in the Cs-U-O system in the temperature range from 873 to 1273 K

    International Nuclear Information System (INIS)

    Fee, D.C.; Johnson, C.E.

    1978-01-01

    Portions of the cesium-uranium-oxygen system have been investigated between 873 and 1273 K and a phase diagram has been constructed using these data and the data of other workers in the field. A consistent set of measured and estimated thermodynamic data for cesium uranates has been used to calculate the equilibrium cesium partial pressure and the equilibrium oxygen partial pressure over two and three phase regions in the Cs-U-O system. For a given temperature, the equilibrium cesium partial pressure in a two phase region decreases as the equilibrium oxygen partial pressure increases. (author)

  2. Proportion of influence phases anatase and rutile TiO{sub 2} in the photoluminescence 538 nm emission wavelength; Influencia da proporcao das fases anatasio e rutilo na fotoluminescincia do TiO{sub 2} em comprimento de onda de emissao de 538 nm

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, D.S.; Diniz, V.C.S.; Araujo, P.M.A.G.; Costa, A.C.F.M., E-mail: dagobertoufcg@gmail.com [Universidade Federal de Campina Grande (UFCG), PB (Brazil); Viana, R.S.; Junior, S.A. [Universidade Federal de Pernambuco (UFPE), PE (Brazil)

    2016-07-01

    TiO2 is one of the most studied materials in the technology area, especially in photoluminescent applications involving catalysts from the biosensor. Therefore, we propose to obtain the Pechini method TiO{sub 2} molar ratio of citric acid/metal ions of 3:1 and 4:1 in order to investigate the influence of the proportion of anatase and rutile phases with the photoluminescence excitation wavelength of 538nm emission. The samples were characterized by X-ray diffraction, thermal analysis and excitation spectroscopy. The results indicate the presence of two phases, with a proportion of 78.99 and 83.58 and 21.01% of anatase and rutile 16.42%, density 3.82 and 3.70 g/cm{sup 3} and excitement in length wave emission 538nm with maximum intensity 91289.2 and 71880,7 cps for samples 3:1 and 4:1, respectively. Sample 3:1 with the highest percentage of rutile phase favored photoluminescence. (author)

  3. Experimental Investigation of Phase Equilibria in the Ho-Ti-Si Ternary System at 973 K (700 °C)

    Science.gov (United States)

    Han, Feng; Zhan, Yongzhong

    2018-02-01

    Phase equilibrium relations of the Ho-Ti-Si ternary system at 973 K (700 °C) were experimentally researched by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectrometer (EDS). The isothermal section of the system at 973 K (700 °C) consists of 14 three-phase regions, 27 two-phase regions, and 14 single-phase regions. The phases Ti5Si3, Ti5Si4, TiSi, TiSi2, Ho5Si3, Ho5Si4, HoSi, αHoSi2-b, and βHoSi2-a are proved to exist at 973 K (700 °C). Previously reported HoTiSi and Ho2Ti3Si4 ternary compounds were confirmed to exist at this temperature. The solubility of Ho in the intermediate phases (i.e., TiSi2, TiSi, Ti5Si4, and Ti5Si3) at the Ti-Si side is extremely small. The maximum solubilities of Ti in HoSi2-b, Ho5Si4, and Ho5Si3 are confirmed to be 8.0, 7.2, and 6.0 at. pct, respectively.

  4. Free energy and phase equilibria for the restricted primitive model of ionic fluids from Monte Carlo simulations

    International Nuclear Information System (INIS)

    Orkoulas, G.; Panagiotopoulos, A.Z.

    1994-01-01

    In this work, we investigate the liquid--vapor phase transition of the restricted primitive model of ionic fluids. We show that at the low temperatures where the phase transition occurs, the system cannot be studied by conventional molecular simulation methods because convergence to equilibrium is slow. To accelerate convergence, we propose cluster Monte Carlo moves capable of moving more than one particle at a time. We then address the issue of charged particle transfers in grand canonical and Gibbs ensemble Monte Carlo simulations, for which we propose a biased particle insertion/destruction scheme capable of sampling short interparticle distances. We compute the chemical potential for the restricted primitive model as a function of temperature and density from grand canonical Monte Carlo simulations and the phase envelope from Gibbs Monte Carlo simulations. Our calculated phase coexistence curve is in agreement with recent results of Caillol obtained on the four-dimensional hypersphere and our own earlier Gibbs ensemble simulations with single-ion transfers, with the exception of the critical temperature, which is lower in the current calculations. Our best estimates for the critical parameters are T * c =0.053, ρ * c =0.025. We conclude with possible future applications of the biased techniques developed here for phase equilibrium calculations for ionic fluids

  5. Thermal analysis and prediction of phase equilibria in the TiO2-Bi2O3 system

    International Nuclear Information System (INIS)

    Lopez-Martinez, Jaqueline; Romero-Serrano, Antonio; Hernandez-Ramirez, Aurelio; Zeifert, Beatriz; Gomez-Yanez, Carlos; Martinez-Sanchez, Roberto

    2011-01-01

    A thermodynamic study on the TiO 2 -Bi 2 O 3 system was carried out using differential thermal analysis (DTA) and X-Ray diffraction (XRD) techniques covering the composition range from 65 to 90 mol% Bi 2 O 3 . From the XRD results the only two intermediate compounds in the Bi 2 O 3 rich region were Bi 4 Ti 3 O 12 and Bi 12 TiO 20 . The Bi 4 Ti 3 O 12 phase presents the well known plate-like morphology. The experimentally determined phase transition temperatures with DTA technique were compared with thermodynamic calculated results and good agreement was obtained. The DTA results also showed that the limit of the peritectic reaction between liquid and Bi 4 Ti 3 O 12 occurs approximately at 90 mol% Bi 2 O 3 . The phase diagram of the TiO 2 -Bi 2 O 3 system was calculated using a quasichemical model for the liquid phase. The thermodynamic properties of the intermediate compounds were estimated from the data of TiO 2 and Bi 2 O 3 pure solids. In this manner, data for this binary system have been analysed and represented with a small adjustable parameter for the liquid phase.

  6. Fluid phase equilibria of the reaction mixture during the selective hydrogenation of 2-butenal in dense carbon dioxide

    DEFF Research Database (Denmark)

    Musko, Nikolai; Jensen, Anker Degn; Baiker, Alfons

    2012-01-01

    Knowledge of the phase behaviour and composition is of paramount importance for understanding multiphase reactions. We have investigated the effect of the phase behaviour in the palladium-catalysed selective hydrogenation of 2-butenal to saturated butanal in dense carbon dioxide. The reactions were...... cell. The results of the catalytic experiments showed that small amounts of carbon dioxide added to the system significantly decrease the conversion, whereas at higher loadings of CO2 the reaction rate gradually increases reaching a maximum. The CPA calculations revealed that this maximum is achieved...... performed using a 5wt% Pd on activated carbon in custom-designed high pressure autoclaves at 323K. The Cubic-Plus-Association (CPA) equation of state was employed to model the phase behaviour of the experimentally studied systems. CPA binary interaction parameters were estimated based on the experimental...

  7. Phase equilibria in the CdMoO4-Gd2(MoO4)3 system

    International Nuclear Information System (INIS)

    Tunik, T.A.; Fedorov, N.F.; Razumovskij, S.N.

    1980-01-01

    The constitutional diagram of the CdMoO 4 -Cd 2 (MoO 4 ) 3 system has been plotted using statistical and dynamic methods as well as a complex of instrumental analysis procedures. Three major phases have been found to occur in the systems, viz.: CdMoO 4 based solid solutions that crystallize in the range from 0 to 25 mol.percent of Cd 2 (MoO 4 ) 3 and pass in transit the two-phase narrow region becoming then solid solutions having a distorted scheelite structure and existing in concentrations from 40 to 65 mol.% of Cd 2 (MoO 4 ) 3 . The entire range, in which the Cd 2 (MoO 4 ) 3 solid solutions can exist, amounts to less than 5 mol.%. Certain crystallochemical constants of the phases that occur in the system have been determined [ru

  8. Critical phenomena in binary fluid mixtures : Classification of phase equilibria with the simplified-perturbed-hard-chain theory

    NARCIS (Netherlands)

    Van Pelt, A.

    1992-01-01

    I. INTRODUCTION AND THEORY This PhD research is mainly concerned with the global phase behaviour, that is calculated from the Simplified-Perturbed-Hard-Chain equation. This equation distinguishes itself from many other equations of state by a sound theoretical background. We enter the field of the

  9. Liquid-liquid phase equilibria for ternary systems of several polyethers with NaCl and H2O

    NARCIS (Netherlands)

    Milosevic, M.; Staal, K.J.J.; Schuur, Boelo; de Haan, A.B.

    2014-01-01

    Liquid–liquid extraction using polymers followed by induced phase separation is a potential energy reducing technology for water–salt separation. Ternary equilibrium data have been determined and reported for the (block co)poly ethers–sodium chloride–water systems at two different temperatures at

  10. Vapor-Liquid Phase Equilibria for Carbon Dioxide-I- Isopentanol Binary System at Elevated Pressure%Vapor-Liquid Phase Equilibria for Carbon Dioxide-I- Isopentanol Binary System at Elevated Pressure

    Institute of Scientific and Technical Information of China (English)

    王琳; 曹丰璞; 刘珊珊; 杨浩

    2011-01-01

    High-pressure vapor-liquid phase equilibrium data for carbon dioxide+ isopentanol were measured at tempera- tures of 313.2, 323.1, 333.5 and 343.4 K in the pressure range of 4.64 to 12.71 MPa in a variable-volume high-pressure visual cell. The experimental data were well correlated with Peng-Robinson equation of state (PR-EOS) together with van der Waals-2 two-parameter mixing rule, and the binary interaction parameters were obtained. Henry coefficients and partial molar volumes of CO2 at infinite dilution were estimated based on Krichevsky-Kasarnovsky equation, and Henry coefficients increase with increasing temperature, however, partial molar volumes of CO2 at infinite dilution are negative and the magnitudes decrease with temperature.

  11. Effect of Secondary Equilibria on the Adsorption of Ibuprofen Enantiomers on a Chiral Stationary Phase with a Grafted Antibiotic Eremomycin

    Science.gov (United States)

    Reshetova, E. N.; Asnin, L. D.; Kachmarsky, K.

    2018-02-01

    The chromatographic separation of ibuprofen enantiomers on a Nautilus-E chiral stationary phase with a grafted eremomycin antibiotic at high column loading is accompanied by distortion of the shape of chromatographic peaks. A model is proposed to explain this phenomenon. A number of factors are considered in the model: the ionization of ibuprofen in the mobile phase, the pH change in the mass transfer zone caused by ionization, and competitive adsorption involving buffer components. Simulations performed using this model within the theory of nonequilibrium chromatography allow the shape of chromatograms for large amounts of S- and R-ibuprofen samples to be predicted. The adsorption mechanism is found to be mainly ion-exchange. The contribution from the molecular adsorption of ibuprofen to the total retention is shown to be several percent.

  12. Role of Acid–Base Equilibria in the Size, Shape, and Phase Control of Cesium Lead Bromide Nanocrystals

    Science.gov (United States)

    2018-01-01

    A binary ligand system composed of aliphatic carboxylic acids and primary amines of various chain lengths is commonly employed in diverse synthesis methods for CsPbBr3 nanocrystals (NCs). In this work, we have carried out a systematic study examining how the concentration of ligands (oleylamine and oleic acid) and the resulting acidity (or basicity) affects the hot-injection synthesis of CsPbBr3 NCs. We devise a general synthesis scheme for cesium lead bromide NCs which allows control over size, size distribution, shape, and phase (CsPbBr3 or Cs4PbBr6) by combining key insights on the acid–base interactions that rule this ligand system. Furthermore, our findings shed light upon the solubility of PbBr2 in this binary ligand system, and plausible mechanisms are suggested in order to understand the ligand-mediated phase control and structural stability of CsPbBr3 NCs. PMID:29381326

  13. TiO2-Based Nanomaterials for Gas Sensing-Influence of Anatase and Rutile Contributions.

    Science.gov (United States)

    Zakrzewska, K; Radecka, M

    2017-12-01

    The paper deals with application of three nanomaterial systems: undoped TiO 2 , chromium-doped TiO 2 :Cr and TiO 2 -SnO 2 synthesized by flame spray synthesis (FSS) technique for hydrogen sensing. The emphasis is put on the role of anatase and rutile polymorphic forms of TiO 2 in enhancing sensitivity towards reducing gases. Anatase-to-rutile transformation is achieved by annealing of undoped TiO 2 in air at 700 °C, specific Cr doping and modification with SnO 2 . Undoped TiO 2 and TiO 2 -SnO 2 exhibit n-type behaviour and while TiO 2 : 5 at.% Cr is a p-type semiconductor. X-ray diffraction (XRD) has been applied to determine anatase-to-rutile weight ratio as well as anatase and rutile crystal size. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) have been used to characterize the structure and morphological parameters. Optical reflectometry enabled to find and compare the band gaps E g of anatase and rutile predominated compositions. Electrical properties, i.e. the electrical conductivity and values of constant phase element (CPE), have been established on the basis of impedance spectroscopy. Dynamic responses of the electrical resistance as a function of hydrogen concentration revealed that predominance of rutile in anatase/rutile mixture is beneficial for gas sensing. Partial transformation to rutile in all three material systems under study resulted in an increased sensitivity towards hydrogen. It is proposed that this effect can be explained in a similar way as in photocatalysis, i.e. by specific band alignment and electron transfer from rutile to anatase to facilitate oxygen preadsorption on the surface of anatase grains.

  14. Ternary equilibria in bismuth--indium--lead alloys

    International Nuclear Information System (INIS)

    Liao, K.C.; Johnson, D.L.; Nelson, R.C.

    1975-01-01

    The liquidus surface is characterized by three binary equilibria. One binary extends from the Pb--Bi peritectic to the Pb--In peritectic. The other two extend from In--Bi eutectics, merge at 50 at. percent Bi and 30 at. percent Pb, and end at the Bi--Pb eutectic. Based on analysis of ternary liquidus contours and vertical sections, it is suggested that solidification for high lead and very high indium alloys occurs from two-phase equilibria. Solidification from all other alloys occurs from three-phase equilibria. Four-phase solidification does not occur in this system

  15. High pressure study of water-salt systems, phase equilibria, partitioning, thermodynic properties and implication for large icy worlds hydrospheres.

    Science.gov (United States)

    Journaux, B.; Brown, J. M.; Abramson, E.; Petitgirard, S.; Pakhomova, A.; Boffa Ballaran, T.; Collings, I.

    2017-12-01

    Water salt systems are predicted to be present in deep hydrosphere inside water-rich planetary bodies, following water/rock chemical interaction during early differentiation stages or later hydrothermal activity. Unfortunately the current knowledge of the thermodynamic and physical properties of aqueous salt mixtures at high pressure and high temperature is still insufficient to allow realistic modeling of the chemical or dynamic of thick planetary hydrospheres. Recent experimental results have shown that the presence of solutes, and more particularly salts, in equilibrium with high pressure ices have large effects on the stability fields, buoyancy and chemistry of all the phases present at these extreme conditions. Effects currently being investigated by our research group also covers ice melting curve depressions that depend on the salt species and incorporation of solutes inside the crystallographic lattice of high pressure ices. Both of these could have very important implication at the planetary scale, enabling thicker/deeper liquid oceans, and allowing chemical transportation through the high pressure ice layer in large icy worlds. We will present the latest results obtained in-situ using diamond anvil cell, coupled with Synchrotron X-Ray diffraction, Raman Spectroscopy and optical observations, allowing to probe the crystallographic structure, equations of state, partitioning and phase boundary of high pressure ice VI and VII in equilibrium with Na-Mg-SO4-Cl ionic species at high pressures (1-10 GPa). The difference in melting behavior depending on the dissolved salt species was characterized, suggesting differences in ionic speciation at liquidus conditions. The solidus P-T conditions were also measured as well as an increase of lattice volumes interpreted as an outcome of ionic incorporation in HP ice during incongruent crystallization. The measured phase diagrams, lattice volumes and important salt incorporations suggest a more complex picture of the

  16. Comparison of two association models (Elliott-Suresh-Donohue and simplified PC-SAFT) for complex phase equilibria of hydrocarbon-water and amine-containing mixtures

    DEFF Research Database (Denmark)

    Grenner, Andreas; Schmelzer, Jürgen; von Solms, Nicolas

    2006-01-01

    , and water. Furthermore, the predictive capabilities of the models are investigated for four ternary systems composed of these components, which exhibit complex liquid-liquid(-liquid) equilibria (LLLE). Various aspects of association models which have an influence in the results are studied for the PC......, both models perform overall similarly for the binary systems, although ESD shows a remarkably good behavior despite its simplicity and the use of only the two-site scheme for all associating compounds. The prediction of the LLE in the ternary systems water + octane + aniline and water + CHA + aniline......Two Wertheim-based association models, the simplified PC-SAFT and the Elliott-Suresh-Donohue (ESD) equation of state, are compared in this work for the description of vapor-liquid equilibria (VLE) and liquid-liquid equilibria (LLE) in binary systems of aniline, cyclohexylamine (CHA), hydrocarbons...

  17. Phase equilibria of toluene/heptane with deep eutectic solvents based on ethyltriphenylphosphonium iodide for the potential use in the separation of aromatics from naphtha

    International Nuclear Information System (INIS)

    Kareem, Mukhtar A.; Mjalli, Farouq S.; Hashim, Mohd Ali; Hadj-Kali, Mohamed K.O.; Ghareh Bagh, Fatemeh Saadat; Alnashef, Inas M.

    2013-01-01

    Highlights: • Ionic liquid analogues are introduced as potential replacements for ionic liquids. • Deep eutectic solvents presented in this work were successful for extracting aromatics. • Hand correlation was applied to ascertain the experimental measurements. • The NRTL thermodynamic model was capable for correlating the LLE experimental data. -- Abstract: In this work, the liquid–liquid extraction of toluene from hydrocarbons mixtures (toluene/heptane) was investigated using deep eutectic solvents as solvents. Ethyltriphenylphosphonium iodide as a salt with either ethylene glycol or sulfolane as hydrogen-bond donors (HBDs) were utilized for synthesizing six DESs. (Liquid + liquid) equilibria data were determined experimentally for the ternary system (toluene + heptane + DES) at (30, 40, 50, and 60) °C and atmospheric pressure. Hand correlation was applied to establish the reliability of the experimental data. In many cases the correlation factor is found close to unity which indicates high reliability of the data. The selectivities and distribution coefficients were used to determine the suitability of these DESs as solvents for this extraction process. Higher selectivities than those published for sulfolane as a commercial solvent were observed. The DES made from ethyltriphenylphosphonium iodide and sulfolane at salt:HBD of 1:4 showed the best separation capability at 30 °C. Thus, it was further characterized by measuring its viscosity and refractive index at a range of temperatures to help understand its physical behaviour needed for process design. The non-random two-liquid (NRTL) model was applied successfully to correlate the experimental tie-lines and to calculate the phase compositions of the ternary systems. It has been found that the third non-randomness parameter varies linearly with the HBD number of moles

  18. Calculation of phase equilibria in Ti-Al-Cr-Mn quaternary system for developing lower cost titanium alloys

    International Nuclear Information System (INIS)

    Lu, X.G.; Li, C.H.; Chen, L.Y.; Qiu, A.T.; Ding, W.Z.

    2011-01-01

    Highlights: → This paper is about the concept of designing the lower cost titanium alloy. → The thermodynamic database of Ti-Al-Cr-Mn system is built up by Calphad method. → The pseudobinary sections with Cr: Mn = 3:1 and Al = 3, 4.5 and 6.0 wt% are calculated. → This may provide the theoretical support for designing the lower cost titanium alloy. - Abstract: The Ti-Al-Cr-Mn system is a potentially useful system for lower cost titanium alloy development; however, there are few reports about the experimental phase diagrams and the thermodynamical assessment for this system. In this study, the previous investigations for the thermodynamic descriptions of the sub-systems in the Ti-Al-Cr-Mn system are reviewed, our previous assessment for the related sub-systems in this quaternary system is summarized, the thermodynamical database of this quaternary system is built up by directly extrapolating from all sub-systems assessed by means of the Calphad method, then the pseudobinary sections with Cr:Mn = 3:1 and Al = 0.0, 3.0, 4.5 and 6.0 wt% are calculated, respectively. These pseudobinary phase diagrams may provide the theoretical support for designing the lower cost titanium alloys with different microstructures (α, α + β, and β titanium alloy).

  19. Phase-equilibria for design of coal-gasification processes: dew points of hot gases containing condensible tars. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Prausnitz, J.M.

    1980-05-01

    This research is concerned with the fundamental physical chemistry and thermodynamics of condensation of tars (dew points) from the vapor phase at advanced temperatures and pressures. Fundamental quantitative understanding of dew points is important for rational design of heat exchangers to recover sensible heat from hot, tar-containing gases that are produced in coal gasification. This report includes essentially six contributions toward establishing the desired understanding: (1) Characterization of Coal Tars for Dew-Point Calculations; (2) Fugacity Coefficients for Dew-Point Calculations in Coal-Gasification Process Design; (3) Vapor Pressures of High-Molecular-Weight Hydrocarbons; (4) Estimation of Vapor Pressures of High-Boiling Fractions in Liquefied Fossil Fuels Containing Heteroatoms Nitrogen or Sulfur; and (5) Vapor Pressures of Heavy Liquid Hydrocarbons by a Group-Contribution Method.

  20. Deep Recycling of Sedimentary Lithologies in Subduction Zones: Geochemical and Physical Constraints from Phase Equilibria and Synchrotron-Based Multi-Anvil Experiments at 15-25 GPa

    Science.gov (United States)

    Rapp, R. P.; Nishiyama, N.; Irifune, T.; Inoue, T.; Yamasaki, D.

    2003-12-01

    Ocean island basalts (OIBs) provide geochemical evidence for the presence of crustally-derived sedimentary material in the deep mantle plume source region for EM-type OIBs, and global seismic tomography provides us with dramatic images of subducted slabs, presumably carrying a sediment component, penetrating through the transition zone and into the lower mantle, in some cases to the core-mantle boundary. In an effort to better constrain the geochemical effects of deeply recycled sedimentary material in subduction zones, and their role in the petrogenesis of EM-type OIBs, we have undertaken a series of phase equlibria experiments in the multi-anvil apparatus at 10-25 GPa, using natural sediment lithologies as starting materials. The goal of these experiments is to identify the dominant phases in deeply subducted sediments, constrain their P-T stability limits, and to assess their role in crustal recycling and element redistribution in the deep mantle during subduction. The phase equilibria experiments were performed in a 2000-ton Kawai-type apparatus, using tungsten carbide cubes with 3 mm TEL and Cr-doped MgO and zirconia pressure media. A cylindrical lanthanum chromite heater was used, along with short (gold capsules to minimize thermal gradients and to retain the small amounts of water (< 1 wt%) present in the starting material, and long run-durations (12-48 hours) in order to facilitate future analyses of the dominant phases for key trace elements using the ion microprobe. Our preliminary results at 10-25 GPa indicate that K-hollandite (KalSi3O3) and stishovite are the primary high-pressure phases in the sediment composition, with subordinate garnet and an as-yet-unidentified (possibly hydrous) Al-silicate phase present as well. These results suggest that K-hollandite is the primary repository for incompatible elements (e.g., La, Ce, Sr, Ba, Rb, etc., and the heat-producing elements K, U and Th) in sedimentary material recycled into the deep mantle via

  1. Study of phase equilibria and glass formation in the CaO-WO3-P2O5 system

    International Nuclear Information System (INIS)

    Bielis, I.Ya.

    1980-01-01

    The method of quenching has been used to investigate the liquidus surface of a portion of the CaO-WO 3 -P 2 O 5 system limited by the Ca(PO 3 ) 2 -W 2 O 3 (PO 4 ) 2 and CaWO 4 -Ca 2 P 2 O 7 cross-sections. The primary crystallization fields on the compounds: WO 3 , W 2 O 3 (PO 4 ) 2 , CaWO 4 , Ca 2 P 7 O 7 , Ca(PO 3 ) 2 are separated. The liquidus surface isotherms at 900, 1000, 1100 and 1200 deg C have been plotted on the concentration triangle plane. It has been found that the cross-sections of W 2 O 3 (PO 4 ) 2 -Ca(PO 3 ) 2 , WO 3 -Ca(PO 3 ) 2 , WO 3 -Ca 2 P 2 O 7 and CaWO 4 -Ca 2 P 2 O 7 are eutectic-type quasi-binary systems. The position of the glass transition region in the CaO-WO 3 -P 2 O 5 system has been determined for the treatment temperatures of 1100, 1200 and 1300 deg C and a correlation between the configuration of the glass transition region and the phase diagram of the system has been demonstrated [ru

  2. Modeling of the phase equilibria of polystyrene in methylcyclohexane with semi-empirical quantum mechanical methods I.

    Science.gov (United States)

    Wilczura-Wachnik, Hanna; Jónsdóttir, Svava Osk

    2003-04-01

    A method for calculating interaction parameters traditionally used in phase-equilibrium computations in low-molecular systems has been extended for the prediction of solvent activities of aromatic polymer solutions (polystyrene+methylcyclohexane). Using ethylbenzene as a model compound for the repeating unit of the polymer, the intermolecular interaction energies between the solvent molecule and the polymer were simulated. The semiempirical quantum chemical method AM1, and a method for sampling relevant internal orientations for a pair of molecules developed previously were used. Interaction energies are determined for three molecular pairs, the solvent and the model molecule, two solvent molecules and two model molecules, and used to calculated UNIQUAC interaction parameters, a(ij) and a(ji). Using these parameters, the solvent activities of the polystyrene 90,000 amu+methylcyclohexane system, and the total vapor pressures of the methylcyclohexane+ethylbenzene system were calculated. The latter system was compared to experimental data, giving qualitative agreement. Figure Solvent activities for the methylcylcohexane(1)+polystyrene(2) system at 316 K. Parameters aij (blue line) obtained with the AM1 method; parameters aij (pink line) from VLE data for the ethylbenzene+methylcyclohexane system. The abscissa is the polymer weight fraction defined as y2(x1)=(1mx1)M2/[x1M1+(1mx1)M2], where x1 is the solvent mole fraction and Mi are the molecular weights of the components.

  3. Phase Equilibria of Mixtures Containing Organic Sulfur Species (OSS) and Water/Hydrocarbons: VLE Measurements and Modeling Using the Cubic-Plus-Association Equation of State

    DEFF Research Database (Denmark)

    Awan, Javeed; Tsivintzelis, Ioannis; Breil, Martin

    2010-01-01

    with the cubic-plus-association (CPA) equation of state. Useful remarks are presented about the application of Henry’s constant values to estimate binary interaction parameters of the CPA EoS for the description of whole vapor−liquid equilibria. The results using CPA EoS show that the cross association...

  4. Vapor Pressure Plus: An Experiment for Studying Phase Equilibria in Water, with Observation of Supercooling, Spontaneous Freezing, and the Triple Point

    Science.gov (United States)

    Tellinghuisen, Joel

    2010-01-01

    Liquid-vapor, solid-vapor, and solid-liquid-vapor equilibria are studied for the pure substance water, using modern equipment that includes specially fabricated glass cells. Samples are evaporatively frozen initially, during which they typically supercool to -5 to -10 [degrees]C before spontaneously freezing. Vacuum pumping lowers the temperature…

  5. The Potential of Soave-Redlich-Kwong Equation of State in Describing Phase Equilibria Data at High Pressures for the CO2 + 1-Alcohol Systems

    Czech Academy of Sciences Publication Activity Database

    Teodorescu, M.; Barhala, A.; Wichterle, Ivan

    2005-01-01

    Roč. 49, č. 11 (2005), s. 927-934 ISSN 0035-3930 R&D Projects: GA ČR(CZ) GA104/03/1555; GA AV ČR(CZ) IAA4072102 Institutional research plan: CEZ:AV0Z40720504 Keywords : vapor liquid equilibria * description Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.226, year: 2005

  6. Phase Equilibria Study in the TeO2-Na2O-SiO2 System in Air Between 723 K (500 °C) and 1473 K (1200 °C)

    Science.gov (United States)

    Santoso, Imam; Taskinen, Pekka

    2016-08-01

    Knowledge of phase equilibria in the TeO2-Na2O-SiO2 system at elevated temperatures is important for ceramic and glass industries and for improving the operation of the smelting process of tellurium-containing materials. A review of previous investigations has indicated, however, that there are omissions in the available datasets on the liquidus temperatures of the molten TeO2-Na2O-SiO2 mixtures. The employed experimental method included equilibration of mixtures made from high purity oxides, rapid quenching of the equilibrated samples in water and followed by compositional analysis of the phases using an electron probe X-ray microanalyzer. The liquidus and phase equilibria in the TeO2-SiO2, TeO2-Na2O, and SiO2-TeO2-Na2O systems have been studied for a wide range of compositions between 723 K (500 °C) and 1473 K (1200 °C) at TeO2, SiO2, and Na2SiO3 saturations. New data have been generated in the SiO2-TeO2-Na2O system at SiO2 saturation. The liquidus compositions in the TeO2-Na2O system at TeO2 saturation have been compared with the previous data and an assessed phase diagram.

  7. The El Teniente porphyry Cu-Mo deposit from a hydrothermal rutile perspective

    Science.gov (United States)

    Rabbia, Osvaldo M.; Hernández, Laura B.; French, David H.; King, Robert W.; Ayers, John C.

    2009-11-01

    Mineralogical, textural, and chemical analyses (EPMA and PIXE) of hydrothermal rutile in the El Teniente porphyry Cu-Mo deposit help to better constrain ore formation processes. Rutile formed from igneous Ti-rich phases (sphene, biotite, Ti-magnetite, and ilmenite) by re-equilibration and/or breakdown under hydrothermal conditions at temperatures ranging between 400°C and 700°C. Most rutile nucleate and grow at the original textural position of its Ti-rich igneous parent mineral phase. The distribution of Mo content in rutile indicates that low-temperature (˜400-550°C), Mo-poor rutile (5.4 ± 1.1 ppm) is dominantly in the Mo-rich mafic wallrocks (high-grade ore), while high-temperature (˜550-700°C), Mo-rich rutile (186 ± 20 ppm) is found in the Mo-poor felsic porphyries (low-grade ore). Rutile from late dacite ring dikes is a notable exception to this distribution pattern. The Sb content in rutile from the high-temperature potassic core of the deposit to its low-temperature propylitic fringe remains relatively constant (35 ± 3 ppm). Temperature and Mo content of the hydrothermal fluids in addition to Mo/Ti ratio, modal abundance and stability of Ti-rich parental phases are key factors constraining Mo content and provenance in high-temperature (≥550°C) rutile. The initial Mo content of parent mineral phases is controlled by melt composition and oxygen fugacity as well as timing and efficiency of fluid-melt separation. Enhanced reduction of SO2-rich fluids and sulfide deposition in the Fe-rich mafic wallrocks influences the low-temperature (≤550°C) rutile chemistry. The data are consistent with a model of fluid circulation of hot (>550°C), oxidized (ƒO2 ≥ NNO + 1.3), SO2-rich and Mo-bearing fluids, likely exsolved from deeper crystallizing parts of the porphyry system and fluxed through the upper dacite porphyries and related structures, with metal deposition dominantly in the Fe-rich mafic wallrocks.

  8. Phase equilibria and crystal chemistry in the ternary system BaO-TiO 2-Nb 2O 5. II. New barium polytitanates with <5 mole% Nb 2O 5

    Science.gov (United States)

    Roth, R. S.; Ettlinger, L. D.; Parker, H. S.

    1987-06-01

    Four new compounds were found in the BaO-TiO 2-Nb 2O 5 system, each containing orth ≈ 9.9A˚, b mon ≈ a orth ≈ 17A˚). Ba 14Ti 40Nb 2O 99 is a 20-layer orthorhombic phase, Cmc*, withc ≈ 46.86A˚. Ba 10Ti 28Nb 2O 72 is a 7-layer monoclinic phase, C2m, c ≈ 16.72A˚, β ≈ 101.2°. Ba 18Ti 54Nb 2O 132 is a 13-layer monoclinic phase, C2m, c ≈ 30.65A˚, β ≈ 96°. The compositions were derived by analogy to the layers in Ba 4Ti 13 O 30 and Ba 6Ti 17O 40 and are consistent with limited phase equilibria data.

  9. Phase equilibria in M-X-X' and M-Al-X ternary systems (M-transition metal, X,X'-B,C,N,Si) and crystal chemistry of ternary compounds

    International Nuclear Information System (INIS)

    Gusev, A.I.

    1996-01-01

    The data on phase equilibria in the M-X-X' and M-Al-X ternary systems (M-transition metal of 3 to 8 groups, X-B,C, N, Si) have been considered and summarized. modern oxygen-free advanced ceramics is based on these ternary systems. Phase diagrams of the 130 ternary systems have been discussed, more than two hundred ternary phases forming in these systems have been systematized and described. The typical crystal structures of ternary compounds and phase have been considered, the common and distinctive features of these structures have been analysed. It has been shown that the ternary compounds with octahedral atomic groups XM 6 have a regions of homogeneity. Refs. 240

  10. Institutions, Equilibria and Efficiency

    DEFF Research Database (Denmark)

    Competition and efficiency is at the core of economic theory. This volume collects papers of leading scholars, which extend the conventional general equilibrium model in important ways. Efficiency and price regulation are studied when markets are incomplete and existence of equilibria in such set...... in OLG, learning in OLG and in games, optimal pricing of derivative securities, the impact of heterogeneity...

  11. Investigation of the phase equilibria and phase transformations associated with the Bi2Sr2CaCu2Oy superconductor

    International Nuclear Information System (INIS)

    Holesinger, T.

    1993-01-01

    The solid solution region and reaction kinetics of the Bi 2 Sr 2 CaCu 2 O y (2212) superconductor were examined as a function of temperature and oxygen partial pressure. Crystallization studies from the glassy and molten states were undertaken to determine the phase transformation and kinetics associated with the formation of 2212 and other competing phases. Crystallization of nominal 2212 glasses was found to proceed in two steps with the formation of Bi 2 Sr 2-x Ca x CuO y (2201) and Cu 2 O followed by Bi 2 Sr 3-x Ca x O y , CaO, and SrO. The 2212 phase converts from the 2201 phase with increasing temperatures. However, its formation below 800 C was kinetically limited. At 800 C and above, a nearly full conversion to the 2212 phase was achieved after only one minute although considerably longer anneal times were necessary for the system to reach equilibrium. In low oxygen partial pressures, the solidus is reduced to approximately 750 C. Solidification studies revealed an eutectic structure separating the incongruently melting 2212/2201 phases at high oxygen partial pressures from the congruently melting Bi 2 Sr 3-x Ca x O y (23x) and Bi 2 Sr 2-x Ca x O y (22x) phases present at low oxygen partial pressures. During solidification in various oxygen partial pressures, the separation of CaO in the melt and the initial crystallization of alkaline-earth cuprates leaves behind a Bi-rich liquid from which it is impossible to form single-phase 2212. Hence, significant amounts of 2201 were also present in these samples. These problems could be reduced by melt processing in inert atmospheres. Bulk 2212 material produced in this manner was found to possess high transition temperatures, high intergranular critical current densities below 20K, and modest critical current densities at 77K

  12. Low temperature self-assembled growth of rutile TiO2/manganese oxide nanocrystalline films

    Science.gov (United States)

    Sun, Zhenya; Zhou, Daokun; Du, Jianhua; Xie, Yuxing

    2017-10-01

    We report formation of rutile TiO2 nanocrystal at low temperature range in the presence of α-MnO2 which self-assembled onto sulfanyl radical activated silicon oxide substrate. SEM, HRTEM, XPS and Raman spectroscopy were used to study the morphology and oxidation state of synthesised crystals. The results showed that when the α-MnO2 was reduced to Mn3O4, it induced the formation of rutile instead of anatase phase in the TiCl4-HCl aqueous system. The finding will promote the understanding of phase transformation mechanism when manganese oxide and titanium oxide co-exist in soil and water environment.

  13. A new approach to establish both stable and metastable phase equilibria for fcc ordered/disordered phase transition: application to the Al–Ni and Ni–Si systems

    International Nuclear Information System (INIS)

    Yuan Xiaoming; Zhang Lijun; Du Yong; Xiong Wei; Tang Ying; Wang Aijun; Liu Shuhong

    2012-01-01

    Both two-sublattice (2SL) and four-sublattice (4SL) models in the framework of the compound energy formalism can be used to describe the fcc ordered/disordered transitions. When transferring the parameters of 2SL disregarding the metastable ordered states into those of 4SL, inconsistence in either stable or metastable phase diagrams could appear, as detected in both Al–Ni and Ni–Si systems. To avoid such a kind of drawback, this behavior was analyzed and investigated in the Ni–Si and Al–Ni systems with the aid of first–principle calculations. Furthermore, a new approach considering both the stable and metastable fcc ordered phase equilibria deduced from the first–principles calculations was proposed to perform a reliable thermodynamic modeling for the fcc ordered/disordered transition. The Ni–Si system was then thermodynamically assessed using the presently proposed approach. The good agreement between the calculation and experiments demonstrates the reliability of the proposed approach. It is expected that the approach is valid for other systems showing complex ordered/disordered transitions. - Highlights: ► We discuss the drawbacks of order/disorder modeling in the Ni–Si and Al–Ni systems. ► We perform ab initio calculation of thermodynamic properties in the Ni–Si system. ► A CALPHAD–type approach is proposed to model the fcc ordered/disordered transition. ► The Ni–Si system was thermodynamically assessed using the new approach.

  14. Zircon-rutile-ilmenite froth flotation process

    International Nuclear Information System (INIS)

    Schmidt, R.; Denham, D.L. Jr.

    1992-01-01

    This patent describes a method for separating a mixture of minerals comprising at least zircon, ilmenite and rutile. It comprises adding an acid solution to the mixture to acidify to a pH of between about 2.0 and 6.0; adding starch to the mixture to depress the ilmenite and the rutile; adding a source of fluoride ions to the mixture to provide a negative surface charge on the zircon surface to activate the zircon; adding an amine cationic collector to the mixture to float the activated zircon; subjecting the mixture containing the added acid solution, the fluoride ions, the starch and the cationic collector, to froth flotation; and withdrawing a float product comprising the zircon and a sink product comprising the ilmenite and rutile

  15. Séparations par changement de phase. Etude et représentation des équilibres liquide-vapeur Separation by Phase Hange. Study and Computing Liquid-Vapor Equilibria

    Directory of Open Access Journals (Sweden)

    Asselineau L.

    2006-11-01

    Full Text Available Pour concevoir et optimiser les principales opérations de séparation (particulièrement les distillations avec ou sans solvant et l'extraction liquide-liquide on doit disposer de méthodes de corrélation ou, mieux, de prédiction des équilibres entre phases. A basse pression, et pour les mélanges d'hydrocarbures, les résultats présentés permettent la prévision des coefficients d'équilibre, même pour les séparations les plus délicates. En présence de constituants polaires, les données expérimentales d'équilibre liquide-liquide et liquide-vapeur de mélanges binaires et ternaires peuvent être simultanément corrélées dans le but de simuler et d'optimiser les distillations azéotropiques ou extractives. Sous haute pression, et particulièrement aux abords immédiats du point critique, le choix d'une équation d'état conduit à un traitement unitaire des phases en présence et permet, en particulier, la prédiction du lieu des points critiques des mélanges d'hydrocarbures et la corrélation de ce lieu en présence de solvants polaires. To determine and optimize the main separation operations (in particular distillations with or without a solvent, and liquid-liquid extraction correlation methods must be available or, better yet, methods of predicting phase equilibria. At low pressure and for hydrocarbon mixtures, the results described make the prediction of equilibrium coefficients possible, even for the most delicate separation. In the presence of polar constituents, the experimental data for the liquid-liquid and liquid-vapor equilibrium of binary and ternary mixtures can be simultaneously correlaten so as to simulate and optimize azeotropic or extractive distillations. Under high pressure and especially in the immediate vicinityof the critical point, the choice of an equation of state leads ta a unit treatment of the phases present and, in particular, makes it possible to predict the location of critical points in hydrocarbon

  16. The role of Nb in rutile-type multi-component antimonates, catalysts for propane ammoxidation

    Energy Technology Data Exchange (ETDEWEB)

    Ballarini, N.; Cavani, F.; Cimini, M.; Trifiro, F. [Dip. Chimica Industriale e Materiali, INSTM, Research Unit of Bologna (Italy); Cornaro, U.; Ghisletti, D. [EniTecnologie SpA, San Donato Milanes (Italy); Catani, R. [Snamprogetti SpA, San Donato Milanese (Italy)

    2005-07-01

    Rutile-type Cr/V/Sb/Nb mixed oxides were prepared by coprecipitation from ethanolic solutions and calcination at 700 C. They were then tested as catalysts for the gas-phase ammoxidation of propane. The addition of increasing amounts of Nb to the rutile Cr/V antimonate led to a considerable increase of the selectivity to acrylonitrile, and to a lower selectivity to N{sub 2} derived from ammonia overoxidation. However, the effect was evident only when excess Sb was present with respect to the stoichiometric requirement for the formation of the rutile compound. Evidences were obtained for the development of rutile-type mixed Cr/V antimonate/niobate, in which the progressive increase of Nb concentration, due to the increased Nb loading, led to the segregation of Sb oxide, in the form of crystalline Sb{sub 2}O{sub 4}. The multi-component rutile was a highly defective structure, and contained excess Sb{sup 5+} and Nb{sup 5+} with respect to the stoichiometric composition. The excess Sb provided the active sites for allcylic ammoxidation on intermediate absorbed propylene. The concomitant presence of Nb in the lattice improved the efficiency of these sites, and was responsible for the better catalytic performance with respect to the Cr/V/Sb/O systems. (orig.)

  17. Possibilities for rutile extraction from Norwegian eclogite by flotation

    OpenAIRE

    Gaydardzhiev, Stoyan; Sandvik, Knut

    1993-01-01

    Preliminary flotations tests towards rutile extraction from Norwegian eclogites (Verving deposit) have been carried out. Various sulfonate type flotation reagents (produced by Hoechts) have been tested. Selectivity between rutile/pyroxene has been targeted. Rutile separation from pyrite and garnet has been further identified as principal problem.

  18. Toroidal Extrap Equilibria

    International Nuclear Information System (INIS)

    Scheffel, J.

    1982-04-01

    Ideal MHD-equilibria for the toroidal EXTRAP configuration have been computed with an equilibrium code. The free-boundary prob- lem is solved by using the condition that the current density is proportional to r on a flux surface. It is found that the toroidal Z-pinch, initially induced in the central zero-field region of a transverse octupole field, drifts radially outwards producing an inverse -D shaped cross-section. The plasma current of this high- beta equilibrium may be increased if the plasma is pushed back by altering the external confining magnetic field as demonstrated. (Author)

  19. Resurrecting Equilibria Through Cycles

    DEFF Research Database (Denmark)

    Barnett, Richard C.; Bhattacharya, Joydeep; Bunzel, Helle

    equilibria because they asymptotically violate some economic restriction of the model. The literature has always ruled out such paths. This paper studies a pure-exchange monetary overlapping generations economy in which real balances cycle forever between momentary equilibrium points. The novelty is to show...... that segments of the offer curve that have been previously ignored, can in fact be used to produce asymptotically valid cyclical paths. Indeed, a cycle can bestow dynamic validity on momentary equilibrium points that had erstwhile been classified as dynamically invalid....

  20. Positron annihilation lifetime characterization of oxygen ion irradiated rutile TiO2

    Science.gov (United States)

    Luitel, Homnath; Sarkar, A.; Chakrabarti, Mahuya; Chattopadhyay, S.; Asokan, K.; Sanyal, D.

    2016-07-01

    Ferromagnetic ordering at room temperature has been induced in rutile phase of TiO2 polycrystalline sample by O ion irradiation. 96 MeV O ion induced defects in rutile TiO2 sample has been characterized by positron annihilation spectroscopic techniques. Positron annihilation results indicate the formation of cation vacancy (VTi, Ti vacancy) in these irradiated TiO2 samples. Ab initio density functional theoretical calculations indicate that in TiO2 magnetic moment can be induced either by creating Ti or O vacancies.

  1. Synthesis of anatase and rutile TiO{sub 2} nanostructures from natural ilmenite

    Energy Technology Data Exchange (ETDEWEB)

    Wahyuingsih, Sayekti, E-mail: sayekti@mipa.uns.ac.id; Ramelan, Ari Handono; Pramono, Edi; Sulistya, Ariantama Djati; Argawan, Panji Rofa; Dharmawan, Frenandha Dwi; Rinawati, Ludfiaastu; Hanif, Qonita Awliya [Inorganic Materials Research Group, Faculty of Mathematic and Natural Science, Sebelas Maret University (Indonesia); Sulistiyono, Eko; Firdiyono, Florentinus [Metallurgy Extraction Laboratory, Central of Metallurgy Research LIPI, Serpong (Indonesia)

    2016-02-08

    Nanostructure anatase and rutile type TiO{sub 2} were synthesized from dissolution roasted ilmenite from natural ilmenite sand as the starting materials. Anatase TiO{sub 2} and rutile TiO{sub 2} (high crystallinity) with the diameters of 20–100 nm were obtained by calcined soluble ilmenite sand produced by leaching process. Calcinations of the xerogel TiO{sub 2} from liquor products were conducted for 4 hours at temperature of 450 °C. The samples were characterized by XRD (X-ray diffraction), STA (simultant thermal analysis), TEM (Transmission Electron Microscopy), and BET surface area. Titania Anatase-Rutile form as a mixture were produced by titania slag with the hydrolysis product. While, in another route, complete titania anatase phase was produced through hydrolysis and condensation steps of leach liquors. This synthesis methods provide a simple route to fabricate nanostructure TiO{sub 2} from low cost material.

  2. Simultaneous synthesis of anatase colloidal and multiple-branched rutile TiO{sub 2} nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Trong Tung; Duong, Ngoc Huyen [School of Engineering Physics, Hanoi University of Science and Technology, Hanoi (Viet Nam); Mai, Xuan Dung [Dept. of Chemistry, Hanoi Pedagogical University No2, Vinh Phuc (Viet Nam)

    2017-03-15

    Facile synthesis of titanium dioxide (TiO{sub 2} ) nanostructures with controllability over their cystallinity, dimensions, and shape is in demand for diverse optoelectronic applications. Anatase colloidal particles and precipitates of rutile bundles were synthesized simultaneously using HCl catalyzed sol–gel process with titanium tetrachloride as Ti precursor. The crystallinity and the morphology of these two separable TiO{sub 2} phases were studied by X-ray diffraction, Raman spectroscopy, and transmission electron microscopy. The results show that by varying HCl concentration during synthesis, dimensions of colloidal anatase can be tuned from spherical particles with a diameter of 2–5 nm to nanorods of dimension of 4 nm (width) × 14 nm (length). The rutile bundles whose size increased with aging time consisted of multiple branches with elongation along c-axis. Both anatase nanorods and rutile bundles can be applied as highly efficient photocatalysts or electron conduits.

  3. Institutions, Equilibria and Efficiency

    DEFF Research Database (Denmark)

    Competition and efficiency is at the core of economic theory. This volume collects papers of leading scholars, which extend the conventional general equilibrium model in important ways. Efficiency and price regulation are studied when markets are incomplete and existence of equilibria in such set......Competition and efficiency is at the core of economic theory. This volume collects papers of leading scholars, which extend the conventional general equilibrium model in important ways. Efficiency and price regulation are studied when markets are incomplete and existence of equilibria...... in such settings is proven under very general preference assumptions. The model is extended to include geographical location choice, a commodity space incorporating manufacturing imprecision and preferences for club-membership, schools and firms. Inefficiencies arising from household externalities or group...... membership are evaluated. Core equivalence is shown for bargaining economies. The theory of risk aversion is extended and the relation between risk taking and wealth is experimentally investigated. Other topics include: determinacy in OLG with cash-in-advance constraints, income distribution and democracy...

  4. Review of Liquidus Surface and Phase Equilibria in the TiO2-SiO2-Al2O3-MgO-CaO Slag System at PO2 Applicable in Fluxed Titaniferous Magnetite Smelting

    Science.gov (United States)

    Goso, Xolisa; Nell, Johannes; Petersen, Jochen

    The current liquidus surface and phase equilibria established in air for fluxed titaniferous magnetite (titanomagnetite) slags conforming to a composition of 37.19% TiO2, 19.69% SiO2, 13.12% Al2O3, and 30.00% of various ratios of CaO+MgO were reviewed at applicable PO2 using FactSage simulation and phase composition of a real plant titanomagnetite slag. The testwork included the incorporation into FactSage of a private MgTi2O5-Al2TiO5 pseudobrookite solution model. The results of the investigation showed that the liquidus surface and Ti3+/ Ti4+ mass fraction ratio increased with decreasing the PO2, At low PO2, perovskite crystallizes as a primary phase at high CaO content. The spinel solution, i.e. (Mg)(Al,Ti)O4, generally crystallizes as the primary phase at high MgO contents, though it is replaced by MgTi2O5-Al2TiO5 solution at PO2 of 10-10 atm to 10-15 atm. An intermediate equilibrium phase diagram established at PO2 of 10-16 atm is proposed. This phase diagram does not show the observed primary phase crystallization competition, however, the phase composition of a real titanomagnetite slag produced by Evraz Highveld Steel and Vanadium Corporation in South Africa does show primary phase crystallization competition between (Mg)(Al,Ti)2O4 and MgTi2O5-Al2TiO5. Smelting involving such slags is likely conducted around the transition PO2, i.e. PO2 of about 10-16 atm. Complex modelling with MgTi2O5, Al2TiO5 and Ti3O5 end members and experiments are underway to verify and update the intermediate phase diagram.

  5. Adsorption analysis equilibria and kinetics

    CERN Document Server

    Do, Duong D

    1998-01-01

    This book covers topics of equilibria and kinetics of adsorption in porous media. Fundamental equilibria and kinetics are dealt with for homogeneous as well as heterogeneous particles. Five chapters of the book deal with equilibria and eight chapters deal with kinetics. Single component as well as multicomponent systems are discussed. In kinetics analysis, we deal with the various mass transport processes and their interactions inside a porous particle. Conventional approaches as well as the new approach using Maxwell-Stefan equations are presented. Various methods to measure diffusivity, such

  6. Quantum equilibria for macroscopic systems

    International Nuclear Information System (INIS)

    Grib, A; Khrennikov, A; Parfionov, G; Starkov, K

    2006-01-01

    Nash equilibria are found for some quantum games with particles with spin-1/2 for which two spin projections on different directions in space are measured. Examples of macroscopic games with the same equilibria are given. Mixed strategies for participants of these games are calculated using probability amplitudes according to the rules of quantum mechanics in spite of the macroscopic nature of the game and absence of Planck's constant. A possible role of quantum logical lattices for the existence of macroscopic quantum equilibria is discussed. Some examples for spin-1 cases are also considered

  7. Quantum equilibria for macroscopic systems

    Energy Technology Data Exchange (ETDEWEB)

    Grib, A [Department of Theoretical Physics and Astronomy, Russian State Pedagogical University, St. Petersburg (Russian Federation); Khrennikov, A [Centre for Mathematical Modelling in Physics and Cognitive Sciences Vaexjoe University (Sweden); Parfionov, G [Department of Mathematics, St. Petersburg State University of Economics and Finances (Russian Federation); Starkov, K [Department of Mathematics, St. Petersburg State University of Economics and Finances (Russian Federation)

    2006-06-30

    Nash equilibria are found for some quantum games with particles with spin-1/2 for which two spin projections on different directions in space are measured. Examples of macroscopic games with the same equilibria are given. Mixed strategies for participants of these games are calculated using probability amplitudes according to the rules of quantum mechanics in spite of the macroscopic nature of the game and absence of Planck's constant. A possible role of quantum logical lattices for the existence of macroscopic quantum equilibria is discussed. Some examples for spin-1 cases are also considered.

  8. Inverse plasma equilibria

    International Nuclear Information System (INIS)

    Hicks, H.R.; Dory, R.A.; Holmes, J.A.

    1983-01-01

    We illustrate in some detail a 2D inverse-equilibrium solver that was constructed to analyze tokamak configurations and stellarators (the latter in the context of the average method). To ensure that the method is suitable not only to determine equilibria, but also to provide appropriately represented data for existing stability codes, it is important to be able to control the Jacobian, tilde J is identical to delta(R,Z)/delta(rho, theta). The form chosen is tilde J = J 0 (rho)R/sup l/rho where rho is a flux surface label, and l is an integer. The initial implementation is for a fixed conducting-wall boundary, but the technique can be extended to a free-boundary model

  9. The nature of excess electrons in anatase and rutile from hybrid DFT and RPA.

    Science.gov (United States)

    Spreafico, Clelia; VandeVondele, Joost

    2014-12-21

    The behavior of excess electrons in undoped and defect free bulk anatase and rutile TiO2 has been investigated by state-of-the-art electronic structure methods including hybrid density functional theory (DFT) and the random phase approximation (RPA). Consistent with experiment, charge trapping and polaron formation is observed in both anatase and rutile. The difference in the anisotropic shape of the polarons is characterized, confirming for anatase the large polaron picture. For anatase, where polaron formation energies are small, charge trapping is observed also with standard hybrid functionals, provided the simulation cell is sufficiently large (864 atoms) to accommodate the lattice relaxation. Even though hybrid orbitals are required as a starting point for RPA in this system, the obtained polaron formation energies are relatively insensitive to the amount of Hartree-Fock exchange employed. The difference in trapping energy between rutile and anatase can be obtained accurately with both hybrid functionals and RPA. Computed activation energies for polaron hopping and delocalization clearly show that anatase and rutile might have different charge transport mechanisms. In rutile, only hopping is likely, whereas in anatase hopping and delocalization are competing. Delocalization will result in conduction-band-like and thus enhanced transport. Anisotropic conduction, in agreement with experimental data, is observed, and results from the tendency to delocalize in the [001] direction in rutile and the (001) plane in anatase. For future work, our calculations serve as a benchmark and suggest RPA on top on hybrid orbitals (PBE0 with 30% Hartree-Fock exchange), as a suitable method to study the rich chemistry and physics of TiO2.

  10. Crystallization and segregation in vitreous rutile films annealed at high temperature

    International Nuclear Information System (INIS)

    Omari, M.A.; Sorbello, R.S.; Aita, C.R.

    2005-01-01

    Vitreous titania films with rutile short-range order were sputter deposited on unheated fused silica substrates, sequentially annealed at 973 and 1273 K, and examined by Raman microscopy, scanning electron microscopy, and x-ray diffraction. A segregated microstructure developed after the 1273 K anneal. This microstructure consists of supermicron-size craters dispersed in a matrix of submicron rutile crystals. Ti-O short-range order in the craters is characteristic of a mixture of two high pressure phases, m-TiO 2 (monoclinic P2 1 /c space group) and α-TiO 2 (tetragonal Pbcn space group). We calculated that a high average compressive stress parallel to the substrate must be accommodated in the films at 1273 K, caused by the difference in the thermal expansion coefficients of titania and fused silica. The formation of the segregated microstructure is modeled by considering two processes at work at 1273 K to lower a film's internal energy: crystallization and nonuniform stress relief. The Gibbs-Thomson relation shows that small m-TiO 2 crystallites are able to form directly from vitreous TiO 2 at 1273 K. However, the preferred mechanism for forming α-TiO 2 is likely to be by epitaxial growth at crystalline rutile twin boundaries (secondary crystallization). Both phases are denser than crystalline rutile and reduce the average thermal stress in the films

  11. Jump conditions in transonic equilibria

    International Nuclear Information System (INIS)

    Guazzotto, L.; Betti, R.; Jardin, S. C.

    2013-01-01

    In the present paper, the numerical calculation of transonic equilibria, first introduced with the FLOW code in Guazzotto et al.[Phys. Plasmas 11, 604 (2004)], is critically reviewed. In particular, the necessity and effect of imposing explicit jump conditions at the transonic discontinuity are investigated. It is found that “standard” (low-β, large aspect ratio) transonic equilibria satisfy the correct jump condition with very good approximation even if the jump condition is not explicitly imposed. On the other hand, it is also found that high-β, low aspect ratio equilibria require the correct jump condition to be explicitly imposed. Various numerical approaches are described to modify FLOW to include the jump condition. It is proved that the new methods converge to the correct solution even in extreme cases of very large β, while they agree with the results obtained with the old implementation of FLOW in lower-β equilibria.

  12. Pierce instability and bifurcating equilibria

    International Nuclear Information System (INIS)

    Godfrey, B.B.

    1981-01-01

    The report investigates the connection between equilibrium bifurcations and occurrence of the Pierce instability. Electrons flowing from one ground plane to a second through an ion background possess a countable infinity of static equilibria, of which only one is uniform and force-free. Degeneracy of the uniform and simplest non-uniform equilibria at a certain ground plan separation marks the onset of the Pierce instability, based on a newly derived dispersion relation appropriate to all the equilibria. For large ground plane separations the uniform equilibrium is unstable and the non-uniform equilibrium is stable, the reverse of their stability properties at small separations. Onset of the Pierce instability at the first bifurcation of equilibria persists in more complicated geometries, providing a general criterion for marginal stability. It seems probable that bifurcation analysis can be a useful tool in the overall study of stable beam generation in diodes and transport in finite cavities

  13. Liquid–liquid equilibria in the quinary aqueous two-phase system of poly(ethylene glycol) 6000 + sodium sulfate + water in the presence of glucose and ethanol: Experimental investigation and thermodynamic modeling

    International Nuclear Information System (INIS)

    Hekayati, Javad; Roosta, Aliakbar; Javanmardi, Jafar

    2016-01-01

    Highlights: • Quinary LLE phase equilibria involving PEG 6000 + Na_2SO_4 + H_2O + glucose + ethanol. • Favorable partition coefficients of ethanol and glucose. • Satisfactory correlation of the LLE experimental data with the original NRTL model. • Root mean squared deviations (RMSDs) of less than 0.6%. - Abstract: Extractive fermentation processes involving aqueous two-phase systems (ATPSs) are considered as viable means of overcoming the problems associated with product inhibition. Practical development of these processes requires accurate knowledge of the liquid–liquid equilibrium (LLE) of the ATPS forming components alongside the substrate and product of the fermentation process. In this work, the quinary aqueous two-phase LLE of poly(ethylene glycol) 6000 + sodium sulfate + water in the presence of glucose and ethanol have been experimentally determined at 298.15 K using spectrophotometric methods. The resulting LLE data were then satisfactorily correlated by the non-random two-liquid (NRTL) activity coefficient model based on mass fractions. In doing so, the binary energy interaction parameters of the NRTL activity coefficient model were obtained and reported. Calculated RMS deviations below 0.6% demonstrate that the original NRTL activity coefficient model can accurately correlate the LLE data of the quinary aqueous biphasic system of interest.

  14. Liquid–liquid equilibria in the quinary aqueous two-phase system of poly(ethylene glycol) 6000 + sodium sulfate + water in the presence of glucose and ethanol: Experimental investigation and thermodynamic modeling

    Energy Technology Data Exchange (ETDEWEB)

    Hekayati, Javad; Roosta, Aliakbar, E-mail: aa.roosta@sutech.ac.ir; Javanmardi, Jafar

    2016-02-10

    Highlights: • Quinary LLE phase equilibria involving PEG 6000 + Na{sub 2}SO{sub 4} + H{sub 2}O + glucose + ethanol. • Favorable partition coefficients of ethanol and glucose. • Satisfactory correlation of the LLE experimental data with the original NRTL model. • Root mean squared deviations (RMSDs) of less than 0.6%. - Abstract: Extractive fermentation processes involving aqueous two-phase systems (ATPSs) are considered as viable means of overcoming the problems associated with product inhibition. Practical development of these processes requires accurate knowledge of the liquid–liquid equilibrium (LLE) of the ATPS forming components alongside the substrate and product of the fermentation process. In this work, the quinary aqueous two-phase LLE of poly(ethylene glycol) 6000 + sodium sulfate + water in the presence of glucose and ethanol have been experimentally determined at 298.15 K using spectrophotometric methods. The resulting LLE data were then satisfactorily correlated by the non-random two-liquid (NRTL) activity coefficient model based on mass fractions. In doing so, the binary energy interaction parameters of the NRTL activity coefficient model were obtained and reported. Calculated RMS deviations below 0.6% demonstrate that the original NRTL activity coefficient model can accurately correlate the LLE data of the quinary aqueous biphasic system of interest.

  15. Quaternary (liquid + liquid) equilibria of aqueous two-phase polyethylene glycol, poly-N-vinylcaprolactam, and KH{sub 2}PO{sub 4}: Experimental and the generalized Flory-Huggins theory

    Energy Technology Data Exchange (ETDEWEB)

    Foroutan, Masumeh [Department of Physical Chemistry, Faculty of Chemistry, College of Science, University of Tehran, Enghelab Ave., Tehran 14155-6455 (Iran, Islamic Republic of)], E-mail: foroutan@khayam.ut.ac.ir; Zarrabi, Mona [Department of Physical Chemistry, Faculty of Chemistry, College of Science, University of Tehran, Enghelab Ave., Tehran 14155-6455 (Iran, Islamic Republic of)

    2008-06-15

    A quaternary (liquid + liquid) equilibrium study was performed to focus attention on the interaction parameters between poly-N-vinylcaprolactam (PVCL) and poly-ethylene glycol (PEG) as well as between other species. At first, the new experimental data of (liquid + liquid) equilibria for aqueous two-phase systems containing PEG, KH{sub 2}PO{sub 4}, and PVCL at T = 303.15 K have been determined. Then the Flory-Huggins theory with two electrostatic terms (the Debye-Huckel and the Pitzer-Debye-Huckel equations) has been generalized to correlate the phase behavior of the quaternary system. Good agreement has been found between experimental and calculated data from both models especially from the Pitzer-Debye-Huckel equation. Also an effort was done to compare the effect of temperature as well as addition of PVCL on the binodal curves of PEG, KH{sub 2}PO{sub 4}, and water. The effect of the type of salt on the binodals has been also studied, and the salting out power of the salts has been determined.

  16. Plasma sprayed rutile titania-nanosilver antibacterial coatings

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Jinjin [Key Lab of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Zhao, Chengjian [National Key Laboratory of Human Factors Engineering, Department of ECLSS, China Astronaut Researching and Training Center, Beijing, 100094 (China); Zhou, Jingfang [Ian Wark Research Institute, University of South Australia, Mawson Lakes Campus, Mawson Lakes, SA, 5095 (Australia); Li, Chunxia [National Key Laboratory of Human Factors Engineering, Department of ECLSS, China Astronaut Researching and Training Center, Beijing, 100094 (China); Shao, Yiran; Shi, Chao [Key Lab of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Zhu, Yingchun, E-mail: yzhu@mail.sic.ac.cn [Key Lab of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

    2015-11-15

    Graphical abstract: - Highlights: • TiO{sub 2}/Ag feedstock powders containing 1–10,000 ppm silver nanoparticles were double sintered and deposited by plasma spray. • TiO{sub 2}/Ag coatings were composed of pure rutile phase and homogeneously-distributed metallic silver. • TiO{sub 2}/Ag coatings with more than 10 ppm silver nanoparticles exhibited strong antibacterial activity against E. coli and S. aureus. - Abstract: Rutile titania (TiO{sub 2}) coatings have superior mechanical properties and excellent stability that make them preferential candidates for various applications. In order to prevent infection arising from bacteria, significant efforts have been focused on antibacterial TiO{sub 2} coatings. In the study, titania-nanosilver (TiO{sub 2}/Ag) coatings with five different kinds of weight percentages of silver nanoparticles (AgNPs) were prepared by plasma spray. The feedstock powders, which had a composition of rutile TiO{sub 2} powders containing 1–10,000 ppm AgNPs, were double sintered and deposited on stainless steel substrates with optimized spraying parameters. X-Ray diffraction and scanning electron microscopy were used to analysize the phase composition and surface morphology of TiO{sub 2}/Ag powders and coatings. Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were employed to examine the antibacterial activity of the as-prepared coatings by bacterial counting method. The results showed that silver existed homogeneously in the TiO{sub 2}/Ag coatings and no crystalline changed happened in the TiO{sub 2} structure. The reduction ratios on the TiO{sub 2}/Ag coatings with 10 ppm AgNPs were as high as 94.8% and 95.6% for E. coli and S. aureus, respectively, and the TiO{sub 2}/Ag coatings with 100–1000 ppm AgNPs exhibited 100% bactericidal activity against E. coli and S. aureus, which indicated the TiO{sub 2}/Ag coatings with more than 10 ppm AgNPs had strong antibacterial activity. Moreover, the main factors influencing the

  17. Plasma sprayed rutile titania-nanosilver antibacterial coatings

    International Nuclear Information System (INIS)

    Gao, Jinjin; Zhao, Chengjian; Zhou, Jingfang; Li, Chunxia; Shao, Yiran; Shi, Chao; Zhu, Yingchun

    2015-01-01

    Graphical abstract: - Highlights: • TiO_2/Ag feedstock powders containing 1–10,000 ppm silver nanoparticles were double sintered and deposited by plasma spray. • TiO_2/Ag coatings were composed of pure rutile phase and homogeneously-distributed metallic silver. • TiO_2/Ag coatings with more than 10 ppm silver nanoparticles exhibited strong antibacterial activity against E. coli and S. aureus. - Abstract: Rutile titania (TiO_2) coatings have superior mechanical properties and excellent stability that make them preferential candidates for various applications. In order to prevent infection arising from bacteria, significant efforts have been focused on antibacterial TiO_2 coatings. In the study, titania-nanosilver (TiO_2/Ag) coatings with five different kinds of weight percentages of silver nanoparticles (AgNPs) were prepared by plasma spray. The feedstock powders, which had a composition of rutile TiO_2 powders containing 1–10,000 ppm AgNPs, were double sintered and deposited on stainless steel substrates with optimized spraying parameters. X-Ray diffraction and scanning electron microscopy were used to analysize the phase composition and surface morphology of TiO_2/Ag powders and coatings. Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were employed to examine the antibacterial activity of the as-prepared coatings by bacterial counting method. The results showed that silver existed homogeneously in the TiO_2/Ag coatings and no crystalline changed happened in the TiO_2 structure. The reduction ratios on the TiO_2/Ag coatings with 10 ppm AgNPs were as high as 94.8% and 95.6% for E. coli and S. aureus, respectively, and the TiO_2/Ag coatings with 100–1000 ppm AgNPs exhibited 100% bactericidal activity against E. coli and S. aureus, which indicated the TiO_2/Ag coatings with more than 10 ppm AgNPs had strong antibacterial activity. Moreover, the main factors influencing the antibacterial properties of TiO_2/Ag coatings were discussed with

  18. Collisionless current sheet equilibria

    Science.gov (United States)

    Neukirch, T.; Wilson, F.; Allanson, O.

    2018-01-01

    Current sheets are important for the structure and dynamics of many plasma systems. In space and astrophysical plasmas they play a crucial role in activity processes, for example by facilitating the release of magnetic energy via processes such as magnetic reconnection. In this contribution we will focus on collisionless plasma systems. A sensible first step in any investigation of physical processes involving current sheets is to find appropriate equilibrium solutions. The theory of collisionless plasma equilibria is well established, but over the past few years there has been a renewed interest in finding equilibrium distribution functions for collisionless current sheets with particular properties, for example for cases where the current density is parallel to the magnetic field (force-free current sheets). This interest is due to a combination of scientific curiosity and potential applications to space and astrophysical plasmas. In this paper we will give an overview of some of the recent developments, discuss their potential applications and address a number of open questions.

  19. Experimental study and modelling of competitive adsorption equilibria of aromatics in liquid phase on X and Y faujasites; Etude experimentale et modelisation des equilibres d'adsorption competitive d'aromatiques en phase liquide sur des faujasites X et Y

    Energy Technology Data Exchange (ETDEWEB)

    Tournier, H.

    2000-10-13

    The separation of p-xylene from C{sub 8} aromatics is performed industrially by selective adsorption on zeolitic molecular sieves. The aim of this work is to study and model adsorption equilibria of C{sub 8} and C{sub 10} aromatics on X and Y zeolites. The experimental data are obtained by an entirely automated equipment allowing to work in a large range of temperature (50 deg. C - 250 deg. C). With this equipment, we can follow the evolution of the composition of the liquid phase and determine the composition of the adsorbed phase at equilibrium by a mass balance calculation and with an inert component. Two analytical techniques are used to determine the composition of the liquid phase: (1) a classical method using a gas chromatograph (GC) allowed to measure selectivities in the concentration range (3%-97%) in a component; (2) an original method based on the use and on the measure of {sup 13}C labelled xylenes was developed to investigate the ranges of strongly contrasting concentrations [0-3%] and [97%-100%] in a component, which are representative of high purity domains. Lastly, three thermodynamic models are used to describe the adsorption equilibria: the Langmuir-Freundlich model, the quasi-chemical model and the statistical model. The last model is the more interesting, because it is based on physical considerations. A new statistical model has been developed with taking into account some observations coming from adsorption phenomenon in zeolites. (author)

  20. Cryptographically Blinded Games: Leveraging Players' Limitations for Equilibria and Profit

    DEFF Research Database (Denmark)

    Hubacek, Pavel; Park, Sunoo

    2014-01-01

    In this work we apply methods from cryptography to enable mutually distrusting players to implement broad classes of mediated equilibria of strategic games without trusted mediation. Our implementation uses a pre-play 'cheap talk' phase, consisting of non- binding communication between players...

  1. Modelling of phase equilibria in CH4–C2H6–C3H8–nC4H10–NaCl–H2O systems

    International Nuclear Information System (INIS)

    Li, Jun; Zhang, Zhigang; Luo, Xiaorong; Li, Xiaochun

    2015-01-01

    Highlights: • A new model was established for the phase equilibria of C1–C2–C3–nC4–brine systems. • The model can reproduce of hydrocarbon–brine equilibria to high T&P and salinity. • The model can well predict H 2 O solubility in light hydrocarbon rich phases. - Abstract: A thermodynamic model is presented for the mutual solubility of CH 4 –C 2 H 6 –C 3 H 8 –nC 4 H 10 –brine systems up to high temperature, pressure and salinity. The Peng–Robinson model is used for non-aqueous phase fugacity calculations, and the Pitzer model is used for aqueous phase activity calculations. The model can accurately reproduce the experimental solubilities of CH 4 , C 2 H 6 , C 3 H 8 and nC 4 H 10 in water or NaCl solutions and H 2 O solubility in the non-aqueous phase. The experimental data of mutual solubility for the CH 4 –brine subsystem are sufficient for temperatures exceeding 250 °C, pressures exceeding 1000 bar and NaCl molalities greater than 6 molal. Compared to the CH 4 –brine system, the mutual solubility data of C 2 H 6 –brine, C 3 H 8 –brine and nC 4 H 10 –brine are not sufficient. Based on the comparison with the experimental data of H 2 O solubility in C 2 H 6 -, C 3 H 8 - or nC 4 H 10 -rich phases, the model has an excellent capability for the prediction of H 2 O solubility in hydrocarbon-rich phases, as these experimental data were not used in the modelling. Predictions of hydrocarbon solubility (at temperatures up to 200 °C, pressures up to 1000 bar and NaCl molalities greater than 6 molal) were made for the C 2 H 6 –brine, C 3 H 8 –brine and nC 4 H 10 –brine systems. The predictions suggest that increasing pressure generally increases the hydrocarbon solubility in water or brine, especially in the lower-pressure region. Increasing temperature usually decreases the hydrocarbon solubility at lower temperatures but increases the hydrocarbon solubility at higher temperatures. Increasing water salinity dramatically decreases

  2. Hydrostatic Equilibria of Rotating Stars with Realistic Equation of State

    Science.gov (United States)

    Yasutake, Nobutoshi; Fujisawa, Kotaro; Okawa, Hirotada; Yamada, Shoichi

    Stars rotate generally, but it is a non-trivial issue to obtain hydrostatic equilibria for rapidly rotating stars theoretically, especially for baroclinic cases, in which the pressure depends not only on the density, but also on the temperature and compositions. It is clear that the stellar structures with realistic equation of state are the baroclinic cases, but there are not so many studies for such equilibria. In this study, we propose two methods to obtain hydrostatic equilibria considering rotation and baroclinicity, namely the weak-solution method and the strong-solution method. The former method is based on the variational principle, which is also applied to the calculation of the inhomogeneous phases, known as the pasta structures, in crust of neutron stars. We found this method might break the balance equation locally, then introduce the strong-solution method. Note that our method is formulated in the mass coordinate, and it is hence appropriated for the stellar evolution calculations.

  3. Phase diagrams of high-order critical phenomene and high-temperature equilibria in the H2O-HgI2-PbI2 system

    International Nuclear Information System (INIS)

    Valyashko, V.M.; Urusova, M.A.

    1996-01-01

    The paper studies the principal schemes of complete state diagram of volatile component-two non-volatile components three-component system with tricritical point and sequence of phase transformations at variation of temperature, pressure and composition of mixture. H 2 O-HgI 2 -PbI 2 system, solid phase dissolving process, stratification of solutions and critical phenomena under 200-400 deg C are studied experimentally. General nature of the system phase diagram and parameters of three-phase equilibrium critical point (tricritical point), that is, gas-liquid 1 -liquid 2 are determined. 17 refs., 8 figs., 3 tabs

  4. Learning to Play Efficient Coarse Correlated Equilibria

    KAUST Repository

    Borowski, Holly P.; Marden, Jason R.; Shamma, Jeff S.

    2018-01-01

    The majority of the distributed learning literature focuses on convergence to Nash equilibria. Coarse correlated equilibria, on the other hand, can often characterize more efficient collective behavior than even the best Nash equilibrium. However

  5. Individual and binary toxicity of anatase and rutile nanoparticles towards Ceriodaphnia dubia

    International Nuclear Information System (INIS)

    Iswarya, V.; Bhuvaneshwari, M.; Chandrasekaran, N.; Mukherjee, Amitava

    2016-01-01

    Highlights: • Individual, binary toxicity of anatase and rutile NPs studied on Ceriodaphnia dubia. • Anatase and rutile phases showed differential effect upon variation in irradiation. • Mixture induced antagonistic at visible and additive effect at UV-A irradiation. • Marking-Dawson model fitted more appropriately than Abbott model. • Agglomeration played a major role in the toxicity induced by the mixture. - Abstract: Increasing usage of engineered nanoparticles, especially Titanium dioxide (TiO_2) in various commercial products has necessitated their toxicity evaluation and risk assessment, especially in the aquatic ecosystem. In the present study, a comprehensive toxicity assessment of anatase and rutile NPs (individual as well as a binary mixture) has been carried out in a freshwater matrix on Ceriodaphnia dubia under different irradiation conditions viz., visible and UV-A. Anatase and rutile NPs produced an LC_5_0 of about 37.04 and 48 mg/L, respectively, under visible irradiation. However, lesser LC_5_0 values of about 22.56 (anatase) and 23.76 (rutile) mg/L were noted under UV-A irradiation. A toxic unit (TU) approach was followed to determine the concentrations of binary mixtures of anatase and rutile. The binary mixture resulted in an antagonistic and additive effect under visible and UV-A irradiation, respectively. Among the two different modeling approaches used in the study, Marking-Dawson model was noted to be a more appropriate model than Abbott model for the toxicity evaluation of binary mixtures. The agglomeration of NPs played a significant role in the induction of antagonistic and additive effects by the mixture based on the irradiation applied. TEM and zeta potential analysis confirmed the surface interactions between anatase and rutile NPs in the mixture. Maximum uptake was noticed at 0.25 total TU of the binary mixture under visible irradiation and 1 TU of anatase NPs for UV-A irradiation. Individual NPs showed highest uptake under

  6. Individual and binary toxicity of anatase and rutile nanoparticles towards Ceriodaphnia dubia

    Energy Technology Data Exchange (ETDEWEB)

    Iswarya, V.; Bhuvaneshwari, M.; Chandrasekaran, N.; Mukherjee, Amitava, E-mail: amit.mookerjea@gmail.com

    2016-09-15

    Highlights: • Individual, binary toxicity of anatase and rutile NPs studied on Ceriodaphnia dubia. • Anatase and rutile phases showed differential effect upon variation in irradiation. • Mixture induced antagonistic at visible and additive effect at UV-A irradiation. • Marking-Dawson model fitted more appropriately than Abbott model. • Agglomeration played a major role in the toxicity induced by the mixture. - Abstract: Increasing usage of engineered nanoparticles, especially Titanium dioxide (TiO{sub 2}) in various commercial products has necessitated their toxicity evaluation and risk assessment, especially in the aquatic ecosystem. In the present study, a comprehensive toxicity assessment of anatase and rutile NPs (individual as well as a binary mixture) has been carried out in a freshwater matrix on Ceriodaphnia dubia under different irradiation conditions viz., visible and UV-A. Anatase and rutile NPs produced an LC{sub 50} of about 37.04 and 48 mg/L, respectively, under visible irradiation. However, lesser LC{sub 50} values of about 22.56 (anatase) and 23.76 (rutile) mg/L were noted under UV-A irradiation. A toxic unit (TU) approach was followed to determine the concentrations of binary mixtures of anatase and rutile. The binary mixture resulted in an antagonistic and additive effect under visible and UV-A irradiation, respectively. Among the two different modeling approaches used in the study, Marking-Dawson model was noted to be a more appropriate model than Abbott model for the toxicity evaluation of binary mixtures. The agglomeration of NPs played a significant role in the induction of antagonistic and additive effects by the mixture based on the irradiation applied. TEM and zeta potential analysis confirmed the surface interactions between anatase and rutile NPs in the mixture. Maximum uptake was noticed at 0.25 total TU of the binary mixture under visible irradiation and 1 TU of anatase NPs for UV-A irradiation. Individual NPs showed highest

  7. Partial Cooperative Equilibria: Existence and Characterization

    Directory of Open Access Journals (Sweden)

    Amandine Ghintran

    2010-09-01

    Full Text Available We study the solution concepts of partial cooperative Cournot-Nash equilibria and partial cooperative Stackelberg equilibria. The partial cooperative Cournot-Nash equilibrium is axiomatically characterized by using notions of rationality, consistency and converse consistency with regard to reduced games. We also establish sufficient conditions for which partial cooperative Cournot-Nash equilibria and partial cooperative Stackelberg equilibria exist in supermodular games. Finally, we provide an application to strategic network formation where such solution concepts may be useful.

  8. Experimental Investigation and Thermodynamic Assessment of Phase Equilibria in the PLLA/Dioxane/Water Ternary System for Applications in the Biomedical Field.

    Science.gov (United States)

    Ruggiero, Flavia; Netti, Paolo Antonio; Torino, Enza

    2015-12-01

    Fundamental understanding of thermodynamic of phase separation plays a key role in tuning the desired features of biomedical devices. In particular, phase separation of ternary solution is of remarkable interest in processes to obtain biodegradable and biocompatible architectures applied as artificial devices to repair, replace, or support damaged tissues or organs. In these perspectives, thermally induced phase separation (TIPS) is the most widely used technique to obtained porous morphologies and, in addition, among different ternary systems, polylactic acid (PLLA)/dioxane/water has given promising results and has been largely studied. However, to increase the control of TIPS-based processes and architectures, an investigation of the basic energetic phenomena occurring during phase separation is still required. Here we propose an experimental investigation of the selected ternary system by using isothermal titration calorimetric approach at different solvent/antisolvent ratio and a thermodynamic explanation related to the polymer-solvents interactions in terms of energetic contribution to the phase separation process. Furthermore, relevant information about the phase diagrams and interaction parameters of the studied systems are furnished in terms of liquid-liquid miscibility gap. Indeed, polymer-solvents interactions are responsible for the mechanism of the phase separation process and, therefore, of the final features of the morphologies; the knowledge of such data is fundamental to control processes for the production of membranes, scaffolds and several nanostructures. The behavior of the polymer at different solvent/nonsolvent ratios is discussed in terms of solvation mechanism and a preliminary contribution to the understanding of the role of the hydrogen bonding in the interface phenomena is also reported. It is the first time that thermodynamic data of a ternary system are collected by mean of nano-isothermal titration calorimetry (nano-ITC). Supporting

  9. Density functional theory study of the mechanism of Li diffusion in rutile RuO2

    International Nuclear Information System (INIS)

    Jung, Jongboo; Cho, Maenghyo; Zhou, Min

    2014-01-01

    First-principle calculations are carried out to study the diffusion of Li ions in rutile structure RuO 2 , a material for positive electrodes in rechargeable Li ion batteries. The calculations focus on migration pathways and energy barriers for diffusion in Li-poor and Li-rich phases using the Nudged Elastic Band Method. Diffusion coefficients estimated based on calculated energy barriers are in good agreement with experimental values reported in the literature. The results confirm the anisotropic nature of diffusion of Li ions in one-dimensional c channels along the [001] crystalline direction of rutile RuO 2 and show that Li diffusion in the Li-poor phase is faster than in the Li-rich phase. The findings of fast Li diffusion and feasible Li insertion at low temperatures in the host rutile RuO 2 suggest this material is a good ionic conductor for Li transport. The finding also suggests possible means for enhancing the performance of RuO 2 -based electrode materials

  10. Modeling phase equilibria for acid gas mixtures using the CPA equation of state. Part IV. Applications to mixtures of CO2 with alkanes

    DEFF Research Database (Denmark)

    Tsivintzelis, Ioannis; Ali, Shahid; Kontogeorgis, Georgios

    2015-01-01

    The thermodynamic properties of pure gaseous, liquid or supercritical CO2 and CO2 mixtures with hydrocarbons and other compounds such as water, alcohols, and glycols are very important in many processes in the oil and gas industry. Design of such processes requires use of accurate thermodynamic...... models, capable of predicting the complex phase behavior of multicomponent mixtures as well as their volumetric properties. In this direction, over the last several years, the cubic-plus-association (CPA) thermodynamic model has been successfully used for describing volumetric properties and phase...

  11. Correlation and Prediction of Phase Equilibria and Volumetric Behaviour of Hyperbaric Binary Fluids Corrélation et prédiction des équilibres de phases et du comportement volumétrique de fluides hyperbares binaires

    Directory of Open Access Journals (Sweden)

    Stamataki S. K.

    2006-11-01

    Full Text Available The capabilities of cubic Equations of State (EoS in the correlation and the prediction of phase equilibria at hyperbaric conditions is examined. PVT data of pure compounds as well as VLE and volumetric data of binary mixtures up to 2000 bar are used. Correlation and prediction results are presented with the translated and modified Peng-Robinson (t - mPR EoS and EoS/GE models. The performance of cubic EoS with a single interaction parameter (kij in describing VLE is remarkable considering the level of pressures involved. The same is valid for the PVT results including the relative liquid volumes of the C1/nC24 system. With typical errors of about 10% deviations in pressure of 100 - 200 bar are, of course, encountered which can be eliminated by the use of second interaction coefficient in the covolume combining rule. Predicted kij values obtained from generalized correlations developed from low pressure VLE data provide reasonable results for systems with hydrocarbons up to nC16 even at high pressures, but fail for higher asymmetric ones. Volume translation is essential for PVT predictions. The temperature independent translation of t - mPR and that of Jhaveri and Yougren give very satisfactory results. LCVM provides the best results of the EoS/GE models studied and gives very good predictions for rather symmetric systems which become poorer with asymmetric ones at very high pressures. La capacité des équations d'état (EoS cubiques pour corréler et prédire les équilibres de phases en conditions hyperbares est analysée. Les données PVT de corps purs ainsi que les données d'équilibres liquide-vapeur (VLE et volumétriques pour des mélanges binaires, jusqu'à 2000 bar sont utilisées. Les résultats des corrélations et des prédictions sont présentés pour l'équation de Peng-Robinson translatée et modifiée (t - mPR, ainsi que pour les modèles EoS/GE. Les performances des EoS cubiques avec un paramètre d'interaction unique (kij pour

  12. Stackelberg equilibria and horizontal differentiation

    OpenAIRE

    Lambertini, Luca

    1993-01-01

    This paper proposes a taxonomy of the Stackelberg equilibria emerging from a standard game of horizontal differentiation à la Hotelling in which the strategy set of the sellers in the location stage is the real axis. Repeated leadership appears the most advantageous position. Furthermore, this endogenously yields vertical differentiation between products at equilibrium.

  13. Multiple equilibria of divertor plasmas

    International Nuclear Information System (INIS)

    Vu, H.X.; Prinja, A.K.

    1993-01-01

    A one-dimensional, two-fluid transport model with a temperature-dependent neutral recycling coefficient is shown to give rise to multiple equilibria of divertor plasmas (bifurcation). Numerical techniques for obtaining these multiple equilibria and for examining their stability are presented. Although these numerical techniques have been well known to the scientific community, this is the first time they have been applied to divertor plasma modeling to show the existence of multiple equilibria as well as the stability of these solutions. Numerical and approximate analytical solutions of the present one-dimensional transport model both indicate that there exists three steady-state solutions corresponding to (1) a high-temperature, low-density equilibrium, (2) a low-temperature, high-density equilibrium, and (3) an intermediate-temperature equilibrium. While both the low-temperature and the high-temperature equilibria are stable, with respect to small perturbations in the plasma conditions, the intermediate-temperature equilibrium is physically unstable, i.e., any small perturbation about this equilibrium will cause a transition toward either the high-temperature or low-temperature equilibrium

  14. Phase equilibria in the Zr-Si-B ternary system (Zr-Si-ZrB{sub 2} region) at 1 173 K

    Energy Technology Data Exchange (ETDEWEB)

    Han, Feng; Luo, Hao [Guangxi Univ., Nanning (China). College of Materials Science and Engineering; Guangxi Univ., Nanning (China). Guangxi Key Lab. of Processing for Non-ferrous Metal and Featured Materials; Zhan, Yongzhong [Guangxi Univ., Nanning (China). College of Materials Science and Engineering; Guangxi Univ., Nanning (China). Guangxi Key Lab. of Processing for Non-ferrous Metal and Featured Materials; Guangxi Univ., Nanning (China). Center of Ecological Collaborative Innovation for Aluminum Industry

    2017-10-15

    The isothermal section of the Zr-Si-B ternary system (Zr-Si-ZrB{sub 2} region) at 1 173 K has been experimentally determined. All equilibrated alloys were characterized via X-ray powder diffraction and scanning electron microscopy equipped with energy-dispersive X-ray analysis. A ternary phase Zr{sub 5}(Si{sub 0.86}B{sub 0.14}){sub 3} was found at 1 173 K. The experimental results show that the isothermal section consists of 11 single-phase regions, 26 two-phase regions and 13 three-phase regions. The existence of eight compounds, i.e. ZrSi{sub 2}, ZrSi, Zr{sub 5}Si{sub 4}, Zr{sub 3}Si{sub 2}, Zr{sub 2}Si, ZrB, ZrB{sub 2} and Zr{sub 5}(Si{sub 0.86}B{sub 0.14}){sub 3} in this system has been confirmed in the Zr-Si-ZrB{sub 2} region at 1 173 K.

  15. Towards CO2 sequestration and applications of CO2 hydrates: the effects of tetrahydrofuran on the phase equilibria of CO2 hydrates

    International Nuclear Information System (INIS)

    Khalik, M.S.; Peters, C.J.

    2006-01-01

    The increasing quantity of carbon dioxide (CO 2 ) in the atmosphere has caused widespread global concerns. Capturing CO 2 from its sources and stored it in the form of gas hydrates and application of CO 2 hydrates are among the proposed methods to overcome this problem. In order to make hydrate-based process more attractive, the use of cyclic ethers as promoters is suggested to reduce the required hydrate formation pressure and enhancing the corresponding kinetic rate. In the present work, tetrahydrofuran (THF) is chosen as a hydrate promoter, participating in forming hydrates and produces mixed hydrate together with CO 2 . The pressure and temperature ranges of hydrate stability region are carefully determined through phase equilibrium measurement of the ternary CO 2 , tetrahydrofuran (THF) and water systems. From the experimental results, it is confirmed that the presence of THF in CO 2 + water systems will extend the hydrate formation region to higher temperature at a constant pressure. The extension of the hydrate stability region is depended on the overall concentration of the ternary system. Moreover, four-phase equilibrium of H-Lw-Lv-V is observed in the system, which may be due to a liquid phase split. In the region where the four-phase equilibrium exists, the ternary system loses its concentration dependency of the hydrate equilibrium conditions. (Author)

  16. Thermal analysis and prediction of phase equilibria in the TiO{sub 2}-Bi{sub 2}O{sub 3} system

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Martinez, Jaqueline, E-mail: jacky-411@hotmail.com [Metallurgy and Materials Department, Instituto Politecnico Nacional-ESIQIE, Apdo. P. 118-431, 07051 Mexico D.F (Mexico); Romero-Serrano, Antonio, E-mail: romeroipn@hotmail.com [Metallurgy and Materials Department, Instituto Politecnico Nacional-ESIQIE, Apdo. P. 118-431, 07051 Mexico D.F (Mexico); Hernandez-Ramirez, Aurelio, E-mail: aurelioh@hotmail.com [Metallurgy and Materials Department, Instituto Politecnico Nacional-ESIQIE, Apdo. P. 118-431, 07051 Mexico D.F (Mexico); Zeifert, Beatriz, E-mail: bzeifert@yahoo.com [Metallurgy and Materials Department, Instituto Politecnico Nacional-ESIQIE, Apdo. P. 118-431, 07051 Mexico D.F (Mexico); Gomez-Yanez, Carlos, E-mail: cgomezy@ipn.mx [Metallurgy and Materials Department, Instituto Politecnico Nacional-ESIQIE, Apdo. P. 118-431, 07051 Mexico D.F (Mexico); Martinez-Sanchez, Roberto, E-mail: roberto.martinez@cimav.edu.mx [CIMAV, Av. Miguel de Cervantes 120, Chihuahua C.P.31109 (Mexico)

    2011-03-20

    A thermodynamic study on the TiO{sub 2}-Bi{sub 2}O{sub 3} system was carried out using differential thermal analysis (DTA) and X-Ray diffraction (XRD) techniques covering the composition range from 65 to 90 mol% Bi{sub 2}O{sub 3}. From the XRD results the only two intermediate compounds in the Bi{sub 2}O{sub 3} rich region were Bi{sub 4}Ti{sub 3}O{sub 12} and Bi{sub 12}TiO{sub 20}. The Bi{sub 4}Ti{sub 3}O{sub 12} phase presents the well known plate-like morphology. The experimentally determined phase transition temperatures with DTA technique were compared with thermodynamic calculated results and good agreement was obtained. The DTA results also showed that the limit of the peritectic reaction between liquid and Bi{sub 4}Ti{sub 3}O{sub 12} occurs approximately at 90 mol% Bi{sub 2}O{sub 3}. The phase diagram of the TiO{sub 2}-Bi{sub 2}O{sub 3} system was calculated using a quasichemical model for the liquid phase. The thermodynamic properties of the intermediate compounds were estimated from the data of TiO{sub 2} and Bi{sub 2}O{sub 3} pure solids. In this manner, data for this binary system have been analysed and represented with a small adjustable parameter for the liquid phase.

  17. Studies on the liquid-liquid phase distribution equilibria of selenium and its measurement in water using extraction plant with a pulsation column

    International Nuclear Information System (INIS)

    Iskanderani, F.; Sobhi, K.M.; Ejaz, M.

    1989-01-01

    Normal heptane, xylene and a 0.01 molar solution of 4-(5-nonyl)pyridine in toluene were investigated as extractants for selenium(IV) from nitric acid media in potassium iodide. Various parameters affecting the distribution of the element are investigated. Extraction at high aqueous to organic phase volume ratio was studied, using a liquid-liquid extraction plant with a pulsation column. The results were employed to measure selenium in spiked water samples. (author) 24 refs.; 8 figs

  18. A rapid hydrothermal synthesis of rutile SnO2 nanowires

    International Nuclear Information System (INIS)

    Lupan, O.; Chow, L.; Chai, G.; Schulte, A.; Park, S.; Heinrich, H.

    2009-01-01

    Tin oxide (SnO 2 ) nanowires with rutile structure have been synthesized by a facile hydrothermal method at 98 deg. C. The morphologies and structural properties of the as-grown nanowires/nanoneedles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction, X-ray diffraction and Raman spectroscopy. The SEM images reveal tetragonal nanowires of about 10-100 μm in length and 50-100 nm in radius. The Raman scattering peaks indicate a typical rutile phase of the SnO 2 . The effects of molar ratio of SnCl 4 to NH 4 OH on the growth mechanism are discussed

  19. Excess electrons in reduced rutile and anatase TiO2

    Science.gov (United States)

    Yin, Wen-Jin; Wen, Bo; Zhou, Chuanyao; Selloni, Annabella; Liu, Li-Min

    2018-05-01

    As a prototypical photocatalyst, TiO2 is a material of scientific and technological interest. In photocatalysis and other applications, TiO2 is often reduced, behaving as an n-type semiconductor with unique physico-chemical properties. In this review, we summarize recent advances in the understanding of the fundamental properties and applications of excess electrons in reduced, undoped TiO2. We discuss the characteristics of excess electrons in the bulk and at the surface of rutile and anatase TiO2 focusing on their localization, spatial distribution, energy levels, and dynamical properties. We examine specific features of the electronic states for photoexcited TiO2, for intrinsic oxygen vacancy and Ti interstitial defects, and for surface hydroxyls. We discuss similarities and differences in the behaviors of excess electrons in the rutile and anatase phases. Finally, we consider the effect of excess electrons on the reactivity, focusing on the interaction between excess electrons and adsorbates.

  20. Construction of anatase/rutile TiO2 hollow boxes for highly efficient photocatalytic performance

    Science.gov (United States)

    Jia, Changchao; Zhang, Xiao; Yang, Ping

    2018-02-01

    Hollow TiO2 hierarchical boxes with suitable anatase and rutile ratios were designed for photocatalysis. The unique hierarchical structure was fabricated via a Topotactic synthetic method. CaTiO3 cubes were acted as the sacrificial templates to create TiO2 hollow hierarchical boxes with well-defined phase distribution. The phase composition of the hollow TiO2 hierarchical boxes is similar to that of TiO2 P25 nanoparticles (∼80% anatase, and 20% rutile). Compared with nanaoparticles, TiO2 hollow boxes with hierarchical structures exhibited an excellent performance in the photocatalytic degradation of methylene blue organic pollutant. Quantificationally, the degradation rate of the hollow boxes is higher than that of TiO2 P25 nanoparticles by a factor of 2.7. This is ascribed that hollow structure provide an opportunity for using incident light more efficiently. The surface hierarchical and well-organized porous structures are beneficial to supply more active sites and enough transport channels for reactant molecules. The boxes consist of single crystal anatase and rutile combined well with each other, which gives photon-generated carriers transfer efficiently.

  1. EQUILGAS: Program to estimate temperatures and in situ two-phase conditions in geothermal reservoirs using three combined FT-HSH gas equilibria models

    Science.gov (United States)

    Barragán, Rosa María; Núñez, José; Arellano, Víctor Manuel; Nieva, David

    2016-03-01

    Exploration and exploitation of geothermal resources require the estimation of important physical characteristics of reservoirs including temperatures, pressures and in situ two-phase conditions, in order to evaluate possible uses and/or investigate changes due to exploitation. As at relatively high temperatures (>150 °C) reservoir fluids usually attain chemical equilibrium in contact with hot rocks, different models based on the chemistry of fluids have been developed that allow deep conditions to be estimated. Currently either in water-dominated or steam-dominated reservoirs the chemistry of steam has been useful for working out reservoir conditions. In this context, three methods based on the Fischer-Tropsch (FT) and combined H2S-H2 (HSH) mineral-gas reactions have been developed for estimating temperatures and the quality of the in situ two-phase mixture prevailing in the reservoir. For these methods the mineral buffers considered to be controlling H2S-H2 composition of fluids are as follows. The pyrite-magnetite buffer (FT-HSH1); the pyrite-hematite buffer (FT-HSH2) and the pyrite-pyrrhotite buffer (FT-HSH3). Currently from such models the estimations of both, temperature and steam fraction in the two-phase fluid are obtained graphically by using a blank diagram with a background theoretical solution as reference. Thus large errors are involved since the isotherms are highly nonlinear functions while reservoir steam fractions are taken from a logarithmic scale. In order to facilitate the use of the three FT-HSH methods and minimize visual interpolation errors, the EQUILGAS program that numerically solves the equations of the FT-HSH methods was developed. In this work the FT-HSH methods and the EQUILGAS program are described. Illustrative examples for Mexican fields are also given in order to help the users in deciding which method could be more suitable for every specific data set.

  2. High-Pressure Phase Equilibria in Systems Containing CO2 and Ionic Liquid of the [Cnmim][Tf2N] Type

    OpenAIRE

    Sedláková, Z. (Zuzana); Wagner, Z. (Zdeněk)

    2012-01-01

    In this review, we present a comparison of the high-pressure phase behaviour of binary systems constituted of CO2 and ionic liquids of the [Cn(m)mim][Tf2N] type. The comparative study shows that the solubility of CO2 in ionic liquids of the [Cnmim][Tf2N] type generally increases with increasing pressure and decreasing temperature, but some peculiarities have been observed. The solubility of CO2 in ionic liquid solvents was correlated using the Soave–Redlich–Kwong equation of state. The result...

  3. Novel monoclinic zirconolite in Bi2O3–CuO–Ta2O5 ternary system: Phase equilibria, structural and electrical properties

    International Nuclear Information System (INIS)

    Tan, K.B.; Chon, M.P.; Khaw, C.C.; Zainal, Z.; Taufiq Yap, Y.H.; Tan, P.Y.

    2014-01-01

    Highlights: • Novel BCT monoclinic zirconolite phase was prepared through solid state reaction. • Comprehensive study of reaction mechanism was performed by careful firing control. • Qualitative structural and phase analyses were conducted. • Electrical response in broad range of temperature and frequency was investigated. - Abstract: Synthesis of novel monoclinic zirconolite, Bi 1.92 Cu 0.08 (Cu 0.3 Ta 0.7 ) 2 O 7.06 (β-BCT) using solid state reaction had been finalised at the firing temperature of 900 °C over 24 h. The X–ray diffraction pattern of β-BCT was fully indexed on a monoclinic symmetry, space group, C2/c with lattice constants, a = 13.1052 (8), b = 7.6749 (5), c = 12.162 (6), α = γ = 90° and β = 101.32° (1), respectively. The reaction mechanism study indicated phase formation was greatly influenced by the reaction between intermediate bismuth tantalate binary phases and CuO at elevated temperatures. β-BCT was thermally stable up to a temperature of 900 °C and contained spherulite grains with sizes ranging from 1 to 14 μm. Electrical properties of this material were characterised over a broad temperature range covering temperatures from 10 K to 874 K. At the temperature of 304 K, two semicircles were discernible in complex Cole–Cole plot showing an insulating grain boundary with C gb = 6.63 × 10 −9 F cm −1 and a bulk response capacitance, C b = 6.74 × 10 −12 F cm −1 . The Power law frequency-dependent ac conductivity of β-BCT was apparent in three frequency regimes; a low–frequency plateau regime, a high-frequency plateau regime and a dispersive regime taking place in the temperature range of 220–576 K. The frequency-dependent ac conductivity of β-BCT with increasing temperature was attributed to the thermal activated electrical conduction mechanism within the structure

  4. Study of phase equilibria in LiIn(MoO4)2 - MeIn(MoO4)2 (Me - K, Rb) systems

    International Nuclear Information System (INIS)

    Smirnyagina, N.N.; Kozhevnikova, N.M.; Alekseev, F.P.; Mokhosoev, M.V.

    1983-01-01

    To determine the possibilities of formation of ternary molybdates, containing two different alkali cations and a cation of trivalent element, the qUasibinary LiIn(MoO 4 ) 2 -MeIn(MoO 4 ) 2 cross-sections of quaternary Li 2 O-Me 2 O-In 2 O 3 -MoO 3 , (Me-K, Rb) systems have been studied. Methods of X-ray phase-, differential thermal- and crystal optical analyses were used. The studied systems are eutectics with segregation; ternary compounds are not formed in theM

  5. Low-temperature preparation of rutile-type TiO2 thin films for optical coatings by aluminum doping

    Science.gov (United States)

    Ishii, Akihiro; Kobayashi, Kosei; Oikawa, Itaru; Kamegawa, Atsunori; Imura, Masaaki; Kanai, Toshimasa; Takamura, Hitoshi

    2017-08-01

    A rutile-type TiO2 thin film with a high refractive index (n), a low extinction coefficient (k) and small surface roughness (Ra) is required for use in a variety of optical coatings to improve the controllability of the reflection spectrum. In this study, Al-doped TiO2 thin films were prepared by pulsed laser deposition, and the effects of Al doping on their phases, optical properties, surface roughness and nanoscale microstructure, including Al distribution, were investigated. By doping 5 and 10 mol%Al, rutile-type TiO2 was successfully prepared under a PO2 of 0.5 Pa at 350-600 °C. The nanoscale phase separation in the Al-doped TiO2 thin films plays an important role in the formation of the rutile phase. The 10 mol%Al-doped rutile-type TiO2 thin film deposited at 350 °C showed excellent optical properties of n ≈ 3.05, k ≈ 0.01 (at λ = 400 nm) and negligible surface roughness, at Ra ≈ 0.8 nm. The advantages of the superior optical properties and small surface roughness of the 10 mol%Al-doped TiO2 thin film were confirmed by fabricating a ten-layered dielectric mirror.

  6. Thermodynamic study of phase equilibria in petroleum separation plants; Estudo termodinamico do equilibrio de fases em plantas de separacao de petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Ciro Rodolfo Santos; Duarte, Lindemberg de Jesus Nogueira [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil); Santos, Luiz Carlos Lobato [Universidade Federal da Bahia (UFBA), BA (Brazil)

    2012-07-01

    Through a thermodynamic approach of liquid-vapor separation it is possible to provide for a given load, of known composition and given temperature and pressure conditions, which are the volumes and the compositions of liquid and vapor phases in equilibrium. In this sense, the aim of this work is to analyze the separation conditions of the fluids produced in the well 1-FMO-001-BA, belonging to the Field School Project (ANP / UFBA), through a thermodynamic approach of phase equilibrium. This Well is characterized by being in an advanced stage of exploration with low oil and high gas production. Initially, the overall composition of the gas produced from the 1-FMO-001-BA was quantified by gas chromatography and its composition was similar to a typical natural gas found in the Reconcavo's basin. Then, the equilibrium constants were determined by Wilson empirical correlation, which could enable the determination of the dead oil composition. This oil showed low concentration of light hydrocarbons (e.g., methane, etc.) and moderate concentrations of heavy components (e.g., C{sub 10} {sub +}). Moreover, the original composition of the fluid that reaches the separator vessel had a similar chemical composition to the outlet gaseous stream of the separator vessel, proving that the Fazenda Mamoeiro's reservoir is classified as a gas reservoir. Finally, it was determined the relative density of the gas ({gamma} g = 0.8264), the specific gravity of the dead oil ({gamma} {sub o} = 0.7542), the API gravity (56.13) and gas-oil ratio (GOR 950.98 m{sup 3}std / m{sup 3}std), which are consistent with the data provided by PETROBRAS. (author)

  7. Phase equilibria and crystal chemistry of the CaO-½Gd2O3-CoOz system at 885 °C in air

    Science.gov (United States)

    Wong-Ng, W.; Laws, W.; Lapidus, S. H.; Ribaud, L.; Kaduk, J. A.

    2017-10-01

    The CaO-½Gd2O3-CoOz system prepared at 885 °C in air consists of two thermoelectric calcium cobaltate compounds, namely, the 2D thermoelectric oxide solid solution, (Ca3-xGdx)Co4O9-z (0 ≤ x ≤ 0.42) which has a misfit layered structure, and the 1D Ca3Co2O6 compound which consists of chains of alternating CoO6 trigonal prisms and CoO6 octahedra. Ca3Co2O6 was found to be a point compound. In the peripheral binary systems, Gd was not present in the Ca site of CaO, while a small solid solution region was identified for (Gd1-xCax)O(3-z)/2 (0 ≤ x ≤ 0.075). A solid solution region of distorted perovskite, (Gd1-xCax)CoO3-z (0 ≤ x ≤ 0.24, space group Pnma) was established. The structure of a member of the solid solution, (Gd0.92Ca0.08)CoO3-z, was determined using high resolution synchrotron radiation. A ternary oxide compound CaGdCoO4-z which has an orthorhombic structure (Bmab) was found to be stable at this temperature. Five solid solution tie-line regions and six three-phase regions were determined in the CaO-½Gd2O3-CoOz system. A comparison of the phase diagrams of the CaO-½R2O3-CoOz (R = La, Sm and Gd) systems is provided.

  8. MINTEQ, Geochemical Equilibria in Ground Water

    International Nuclear Information System (INIS)

    Krupka, K.M.

    1990-01-01

    1 - Description of program or function: MINTEQ is a geochemical program to model aqueous solutions and the interactions of aqueous solutions with hypothesized assemblages of solid phases. It was developed for the Environmental Protection Agency to perform the calculations necessary to simulate the contact of waste solutions with heterogeneous sediments or the interaction of ground water with solidified wastes. MINTEQ can calculate ion speciation/solubility, adsorption, oxidation-reduction, gas phase equilibria, and precipitation/dissolution of solid phases. MINTEQ can accept a finite mass for any solid considered for dissolution and will dissolve the specified solid phase only until its initial mass is exhausted. This ability enables MINTEQ to model flow-through systems. In these systems the masses of solid phases that precipitate at earlier pore volumes can be dissolved at later pore volumes according to thermodynamic constraints imposed by the solution composition and solid phases present. The ability to model these systems permits evaluation of the geochemistry of dissolved traced metals, such as low-level waste in shallow land burial sites. MINTEQ was designed to solve geochemical equilibria for systems composed of one kilogram of water, various amounts of material dissolved in solution, and any solid materials that are present. Systems modeled using MINTEQ can exchange energy and material (open systems) or just energy (closed systems) with the surrounding environment. Each system is composed of a number of phases. Every phase is a region with distinct composition and physically definable boundaries. All of the material in the aqueous solution forms one phase. The gas phase is composed of any gaseous material present, and structurally distinct solid forms a separate phase. 2 - Method of solution: MINTEQ applies the fundamental principles of thermodynamics to solve geochemical equilibria from a set of mass balance equations, one for each component. Because the

  9. Eutectic, monotectic and immiscibility systems of nimesulide with water-soluble carriers: phase equilibria, solid-state characterisation and in-vivo/pharmacodynamic evaluation.

    Science.gov (United States)

    Abdelkader, Hamdy; Abdallah, Ossama Y; Salem, Hesham; Alani, Adam W G; Alany, Raid G

    2014-10-01

    The solid-state interactions of fused mixtures nimesulide (ND) with polyethylene glycol (PEG) 4000, urea or mannitol were studied through constructing thaw-melt phase equilibrium diagrams. The solid-state characteristics were investigated using differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Various types of interactions were identified such as the formation of a eutectic system of ND-PEG 4000, monotectic system of ND-urea and complete solid immiscibility of ND with mannitol. The effects of carrier concentrations on the equilibrium solubility and in-vitro dissolution characteristics were studied. Linear increases (R(2)  > 0.99) in the aqueous solubility of ND in various concentrations of PEG 4000 and urea were obtained, whereas mannitol did not exhibit any effect on the solubility of ND. Similar trends were obtained with the dissolution efficiency of the fused mixtures of ND with PEG 4000 and urea compared with the corresponding physical mixtures and untreated drug. The analgesic effects of untreated ND and the selected formulations were investigated by evaluating the drug's ability to inhibit the acetic acid-induced writhing response. The analgesic effect of ND in a eutectic mixture with PEG 4000 and a monotectic mixture with urea was potentiated by 3.2 and 2.7-fold respectively compared with the untreated drug. © 2014 Royal Pharmaceutical Society.

  10. Nash Equilibria in Fisher Market

    Science.gov (United States)

    Adsul, Bharat; Babu, Ch. Sobhan; Garg, Jugal; Mehta, Ruta; Sohoni, Milind

    Much work has been done on the computation of market equilibria. However due to strategic play by buyers, it is not clear whether these are actually observed in the market. Motivated by the observation that a buyer may derive a better payoff by feigning a different utility function and thereby manipulating the Fisher market equilibrium, we formulate the Fisher market game in which buyers strategize by posing different utility functions. We show that existence of a conflict-free allocation is a necessary condition for the Nash equilibria (NE) and also sufficient for the symmetric NE in this game. There are many NE with very different payoffs, and the Fisher equilibrium payoff is captured at a symmetric NE. We provide a complete polyhedral characterization of all the NE for the two-buyer market game. Surprisingly, all the NE of this game turn out to be symmetric and the corresponding payoffs constitute a piecewise linear concave curve. We also study the correlated equilibria of this game and show that third-party mediation does not help to achieve a better payoff than NE payoffs.

  11. Vapor-liquid equilibria for the acetone-ethanol-n-propanol-tert-butanol-water system

    Energy Technology Data Exchange (ETDEWEB)

    Tochigi, K.; Uchida, K.; Kojima, K.

    1981-12-01

    This study deals with the measurement of vapor-liquid equilibria for the five-component system acetone-ethanol-n-propanol-tert-butanol-water at 760 mmHg and prediction of vapor-liquid equilibria by the ASOG group contribution method. The five-component system in this work is composed of a part of the components obtained during ethanol production by vapor-phase hydration of ethylene. 6 refs.

  12. Calculation of Binary Adsorption Equilibria: Hydrocarbons and Carbon Dioxide on Activated Carbon

    DEFF Research Database (Denmark)

    Marcussen, Lis; Krøll, A.

    1999-01-01

    Binary adsorption equilibria are calculated by means of a mathematical model for multicomponent mixtures combined with the SPD (Spreading Pressure Dependent) model for calculation of activity coefficients in the adsorbed phase. The model has been applied successfully for the adsorption of binary ...... mixtures of hydrocarbons and carbon dioxide on activated carbons. The model parameters have been determined, and the model has proven to be suited for prediction of adsorption equilibria in the investigated systems....

  13. Ion implantation induced blistering of rutile single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, Bing-Xi [School of Physics, Shandong University, Jinan, Shandong 250100 (China); Jiao, Yang [College of Physics and Electronics, Shandong Normal University, Jinan, Shandong 250100 (China); Guan, Jing [School of Physics, Shandong University, Jinan, Shandong 250100 (China); Wang, Lei [School of Physics, Shandong University, Jinan, Shandong 250100 (China); Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences (China)

    2015-07-01

    The rutile single crystals were implanted by 200 keV He{sup +} ions with a series fluence and annealed at different temperatures to investigate the blistering behavior. The Rutherford backscattering spectrometry, optical microscope and X-ray diffraction were employed to characterize the implantation induced lattice damage and blistering. It was found that the blistering on rutile surface region can be realized by He{sup +} ion implantation with appropriate fluence and the following thermal annealing.

  14. An experimental study of Fe-Ni exchange between sulfide melt and olivine at upper mantle conditions: implications for mantle sulfide compositions and phase equilibria

    Science.gov (United States)

    Zhang, Zhou; von der Handt, Anette; Hirschmann, Marc M.

    2018-03-01

    The behavior of nickel in the Earth's mantle is controlled by sulfide melt-olivine reaction. Prior to this study, experiments were carried out at low pressures with narrow range of Ni/Fe in sulfide melt. As the mantle becomes more reduced with depth, experiments at comparable conditions provide an assessment of the effect of pressure at low-oxygen fugacity conditions. In this study, we constrain the Fe-Ni composition of molten sulfide in the Earth's upper mantle via sulfide melt-olivine reaction experiments at 2 GPa, 1200 and 1400 °C, with sulfide melt X_{{{Ni}}}^{{{Sulfide}}}={{Ni}}/{{Ni+{Fe}}} (atomic ratio) ranging from 0 to 0.94. To verify the approach to equilibrium and to explore the effect of {f_{{{O}2}}} on Fe-Ni exchange between phases, four different suites of experiments were conducted, varying in their experimental geometry and initial composition. Effects of Ni secondary fluorescence on olivine analyses were corrected using the PENELOPE algorithm (Baró et al., Nucl Instrum Methods Phys Res B 100:31-46, 1995), "zero time" experiments, and measurements before and after dissolution of surrounding sulfides. Oxygen fugacities in the experiments, estimated from the measured O contents of sulfide melts and from the compositions of coexisting olivines, were 3.0 ± 1.0 log units more reduced than the fayalite-magnetite-quartz (FMQ) buffer (suite 1, 2 and 3), and FMQ - 1 or more oxidized (suite 4). For the reduced (suites 1-3) experiments, Fe-Ni distribution coefficients K_{{D}}{}={(X_{{{Ni}}}^{{{sulfide}}}/X_{{{Fe}}}^{{{sulfide}}})}/{(X_{{{Ni}}^{{{olivine}}}/X_{{{Fe}}}^{{{olivine}}})}} are small, averaging 10.0 ± 5.7, with little variation as a function of total Ni content. More oxidized experiments (suite 4) give larger values of K D (21.1-25.2). Compared to previous determinations at 100 kPa, values of K D from this study are chiefly lower, in large part owing to the more reduced conditions of the experiments. The observed difference does not seem

  15. Magnetoacoustic heating and FCT-equilibria in the belt pinch

    International Nuclear Information System (INIS)

    Erckmann, V.

    1983-02-01

    In the HECTOR belt pinch of high β plasma is produced by magnetic compression in a Tokamak geometry. After compresseion the initial β value can be varied between 0.2 and 0.8. During 5 μs the plasma is further heated by a fast magnetoacoustic wave with a frequency near the first harmonic of the ion cyclotronfrequency. For the first time the β-value of a pinch plasma could be increased further from 0.34 after compression to 0.46 at the end of the rf-heating cycle. By proper selection of the final β-value the region for resonance absorption of the heating wave can be shifted. Strong heating (200 MW) has been observed in the cases, where the resonance region has been located in the center of the plasma. In deuterium discharges an increase in ion temperature is observed during the heating process, whereas the electrons are energetically decoupled, showing no temperature increase. Strong plasma losses are found in the 200 MW range after the rf-heating process. The dominant mechanisms are charge exchange collisions with neutral gas atoms. During rf-heating and the subsequent cooling phase the magnetic flux is frozen due to the high conductivity of the plasma. The observed equilibria could be identified as flux conserving Tokamak (FCT) equilibria. Based on a two-dimensional code the time-evolution of the equilibria has been calculated. The q-profiles are time-independent, with increasing β the magnetic axis of the plasma is shifted towards the outer boundary of the torus, and finally the linear relation between β and βsub(pol), which is characteristic for low-β-equilibria, is no longer valid. Thus for the first time the existence of FCT-equilibria at high β has been demonstrated experimentally together with a qualitative agreement with FCT-theory. (orig./AH) [de

  16. Mechanisms of impurity diffusion in rutile

    International Nuclear Information System (INIS)

    Peterson, N.L.; Sasaki, J.

    1984-01-01

    Tracer diffusion of 46 Sc, 51 Cr, 54 Mn, 59 Fe, 60 Co, 63 Ni, and 95 Zr, was measured as functions of crystal orientation, temperature, and oxygen partial pressure in rutile single crystals using the radioactive tracer sectioning technique. Compared to cation self-diffusion, divalent impurities (e.g., Co and Ni) diffuse extremely rapidly in TiO 2 and exhibit a large anisotropy in the diffusion behavior; divalent-impurity diffusion parallel to the c-axis is much larger than it is perpendicular to the c-axis. The diffusion of trivalent impurity ions (Sc and Cr) and tetravalent impurity ions (Zr) is similar to cation self-diffusion, as a function of temperature and of oxygen partial pressure. The divalent impurity ions Co and Ni apparently diffuse as interstitial ions along open channels parallel to the c-axis. The results suggest that Sc, Cr, and Zr ions diffuse by an interstitialcy mechanism involving the simultaneous and cooperative migration of tetravalent interstitial titanium ions and the tracer-impurity ions. Iron ions diffused both as divalent and as trivalent ions. 8 figures

  17. Phase Equilibria Prediction for Systems Containing Lipids

    DEFF Research Database (Denmark)

    Ana Perederic, Olivia; Cunico, Larissa; Sarup, Bent

    ]. Such developments have led to new challenges regarding the design anddevelopment of better performing processes and products. Despite the advances in propertymodelling and process design techniques available via different computeraidedmethods andtools for the chemical and petrochemical industries, the oleochemical...

  18. Phase equilibria at the Zirconium metal purification

    International Nuclear Information System (INIS)

    Dwiretnani-Sudjoko; Busron-Masduki; Sunardjo; Budi-Sulistyo

    1996-01-01

    It was investigated the research in the purification of zirconium metal, which was results from the reduction process, by adding heat in the vacuum environment. The process was done in batch in the stainless steel reactor, equiped with vacuum pump and electric heater. The investigated variable were process temperature and pressure. From this research it was obtained that equilibrium constant for MgCl 2 and Mg were expressed in the equation K M g C l 2 = 0.9011 P 1 .3779 1.06552 T and K M g = 6.0115P + 1.35256T - 6.93912

  19. Modeling of Phase Equilibria Containing Associating Fluids

    DEFF Research Database (Denmark)

    Derawi, Samer; Kontogeorgis, Georgios

    . The background and main targets for this thesis are presented in Chapter 1. In Chapter 2, a comprehensive review of the application of group contribution (GC) models such as various forms of UNIFAC and the so-called AFC (Atom and Fragment Contributions) correlation model for Pow (octanol-water partition...

  20. Phase Equilibria for Complex Polymer Solutions

    DEFF Research Database (Denmark)

    Lindvig, Thomas; Hestkjær, L. L.; Hansen, A. F.

    2002-01-01

    the content of organic solvents. This work presents an investigation of the three polymer models Entropic-FV (EFV). UNIFAC-FV (UFV) and GC-Flory (GCF) for their capability of predicting solvent activity coefficients in binary systems containing complex polymers. It is possible to obtain good predictions...... at finite concentrations and satisfactory predictions at infinite dilution, particularly with the EFV model. The investigation shows that EFV is the most robust and stable of the models, which indicates that it is the most well suited model for further development of methods for predicting the miscibility...

  1. Stability of relative equilibria of three vortices

    DEFF Research Database (Denmark)

    Aref, Hassan

    2009-01-01

    Three point vortices on the unbounded plane have relative equilibria wherein the vortices either form an equilateral triangle or are collinear. While the stability analysis of the equilateral triangle configurations is straightforward, that of the collinear relative equilibria is considerably mor...

  2. Strong Nash Equilibria and the Potential Maimizer

    NARCIS (Netherlands)

    van Megen, F.J.C.; Facchini, G.; Borm, P.E.M.; Tijs, S.H.

    1996-01-01

    A class of non cooperative games characterized by a `congestion e ect' is studied, in which there exists a strong Nash equilibrium, and the set of Nash equilibria, the set of strong Nash equilibria and the set of strategy pro les maximizing the potential function coincide.The structure of the class

  3. Quantification of rutile in anatase by X-ray diffraction

    International Nuclear Information System (INIS)

    Chavez R, A.

    2001-01-01

    Nowadays the discovering of new and better materials required in all areas of the industry has been lead to the human being to introduce him to this small and great world. The crystalline materials, have properties markedly directional. When it is necessary to realize a quantitative analysis to these materials the task is not easy. The main objective of this work is the research of a real problem, its solution and perfecting of a technique involving the theoretical and experimental principles which allow the quantification of crystalline phases. The chapter 1 treats about the study of crystalline state during the last century, by means of the X-ray diffraction technique. The chapter 2 studies the nature and production of X-rays, the chapter 3 expounds the principles of the diffraction technique which to carry out when it is satisfied the Bragg law studying the powder diffraction method and its applications. In the chapter 4 it is explained how the intensities of the beams diffracted are determined by the atoms positions inside of the elemental cell of the crystal. The properties of the crystalline samples of anatase and rutile are described in the chapter 5. The results of this last analysis are the information which will be processed by means of the auxiliary software: Diffrac AT, Axum and Peakfit as well as the TAFOR and CUANTI software describing this part with more detail in the chapters 6 and 7 where it is mentioned step by step the function of each software until to reach the quantification of crystalline phases, objective of this work. Finally, in the chapter 8 there are a results analysis and conclusions. The contribution of this work is for those learned institutions of limited resources which can tackle in this way the characterization of materials. (Author)

  4. Signaling equilibria in sensorimotor interactions.

    Science.gov (United States)

    Leibfried, Felix; Grau-Moya, Jordi; Braun, Daniel A

    2015-08-01

    Although complex forms of communication like human language are often assumed to have evolved out of more simple forms of sensorimotor signaling, less attention has been devoted to investigate the latter. Here, we study communicative sensorimotor behavior of humans in a two-person joint motor task where each player controls one dimension of a planar motion. We designed this joint task as a game where one player (the sender) possesses private information about a hidden target the other player (the receiver) wants to know about, and where the sender's actions are costly signals that influence the receiver's control strategy. We developed a game-theoretic model within the framework of signaling games to investigate whether subjects' behavior could be adequately described by the corresponding equilibrium solutions. The model predicts both separating and pooling equilibria, in which signaling does and does not occur respectively. We observed both kinds of equilibria in subjects and found that, in line with model predictions, the propensity of signaling decreased with increasing signaling costs and decreasing uncertainty on the part of the receiver. Our study demonstrates that signaling games, which have previously been applied to economic decision-making and animal communication, provide a framework for human signaling behavior arising during sensorimotor interactions in continuous and dynamic environments. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Rutile vanadium antimonates. A new class of catalysts for selective reduction of NO with ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Brazdil, James F.; Ebner, Ann M.; Cavalcanti, Fernando A.P. [BP Chemicals Inc., Cleveland, OH (United States)

    1997-12-31

    This paper describes a new class of vanadium containing oxide catalysts that are active and selective for the selective catalytic reduction of NO with ammonia. Vanadium antimony oxide based catalysts were found to be effective in the conversion of NO with little or no ammonia slippage when tested using gas mixtures containing between 300 and 700ppm NO. X-ray diffraction analyses of the catalysts show that the dominant phase present in the catalyst is vanadium antimonate having a defect rutile crystal structure. The catalysts are active and selective in the ranges of 400-460C and gas hourly space velocities of 3000-8000h{sup -1}

  6. Radiological impact assessment of arc welding supplies rutile

    International Nuclear Information System (INIS)

    Rozas Guinea, S.; Herranz Soler, M.; Perez Marin, C.; Idoeta Hermandorena, R.; Alegria gutierrez, N.; Nunez-Lagos Rogla, R.; Legarda Ibanez, F.

    2013-01-01

    Consumables for welding containing rutile, the coating of the electrode or the filling of tubular thread, are the most widely used and also the most radioactive since the rutile is a mineral containing traces of natural radionuclides, and is therefore considered Normal Occurring Radioactive Material (NORM). As these electrodes and wire are consumed, small particles, aerosols and gases are emitted to the atmosphere of work, and may be inhaled by the welder. Therefore, and also according to the current regulatory framework and work carried out previously by the author on the radiological impact of the process of manufacture and storage of coated rutile electrodes, the objectives are: 1Calcular the internal dose for inhalation during two types of welding, one with electrodes coated and the other with thread. 2 calculate the external dose due to the deposition of particles in the work environment, slag and the immersion of the soldering iron in the cloud of smoke. 3 to assess the radiological impact. (Author)

  7. Phase equilibrium engineering

    CERN Document Server

    Brignole, Esteban Alberto

    2013-01-01

    Traditionally, the teaching of phase equilibria emphasizes the relationships between the thermodynamic variables of each phase in equilibrium rather than its engineering applications. This book changes the focus from the use of thermodynamics relationships to compute phase equilibria to the design and control of the phase conditions that a process needs. Phase Equilibrium Engineering presents a systematic study and application of phase equilibrium tools to the development of chemical processes. The thermodynamic modeling of mixtures for process development, synthesis, simulation, design and

  8. Formation energies of rutile metal dioxides using density functional theory

    DEFF Research Database (Denmark)

    Martinez, Jose Ignacio; Hansen, Heine Anton; Rossmeisl, Jan

    2009-01-01

    We apply standard density functional theory at the generalized gradient approximation (GGA) level to study the stability of rutile metal oxides. It is well known that standard GGA exchange and correlation in some cases is not sufficient to address reduction and oxidation reactions. Especially...... and due to a more accurate description of exchange for this particular GGA functional compared to PBE. Furthermore, we would expect the self-interaction problem to be largest for the most localized d orbitals; that means the late 3d metals and since Co, Fe, Ni, and Cu do not form rutile oxides...

  9. Learning to Play Efficient Coarse Correlated Equilibria

    KAUST Repository

    Borowski, Holly P.

    2018-03-10

    The majority of the distributed learning literature focuses on convergence to Nash equilibria. Coarse correlated equilibria, on the other hand, can often characterize more efficient collective behavior than even the best Nash equilibrium. However, there are no existing distributed learning algorithms that converge to specific coarse correlated equilibria. In this paper, we provide one such algorithm, which guarantees that the agents’ collective joint strategy will constitute an efficient coarse correlated equilibrium with high probability. The key to attaining efficient correlated behavior through distributed learning involves incorporating a common random signal into the learning environment.

  10. Computing Nash equilibria through computational intelligence methods

    Science.gov (United States)

    Pavlidis, N. G.; Parsopoulos, K. E.; Vrahatis, M. N.

    2005-03-01

    Nash equilibrium constitutes a central solution concept in game theory. The task of detecting the Nash equilibria of a finite strategic game remains a challenging problem up-to-date. This paper investigates the effectiveness of three computational intelligence techniques, namely, covariance matrix adaptation evolution strategies, particle swarm optimization, as well as, differential evolution, to compute Nash equilibria of finite strategic games, as global minima of a real-valued, nonnegative function. An issue of particular interest is to detect more than one Nash equilibria of a game. The performance of the considered computational intelligence methods on this problem is investigated using multistart and deflection.

  11. Multiple Equilibria in Noisy Rational Expectations Economies

    DEFF Research Database (Denmark)

    Pálvölgyi, Dömötör; Venter, Gyuri

    with a continuous price function. However, we also construct a tractable class of equilibria with discontinuous prices that have very different economic implications, including (i) jumps and crashes, (ii) significant revisions in uninformed belief due to small changes in the market price, (iii) “upward......-sloping” demand curves, (iv) higher prices leading to future returns that are higher in expectation (price drift) and (v) more positively skewed. Discontinuous equilibria can be arbitrarily close to being fully-revealing. Finally, discontinuous equilibria with the same construction also exist in Hellwig (1980)....

  12. Inefficient equilibria in transition economy

    Directory of Open Access Journals (Sweden)

    Sergei Guriev

    1999-01-01

    Full Text Available The paper studies a general equilibrium in an economy where all market participants face a bid-ask spread. The spread may be caused by indirect business taxes, middlemen rent-seeking, delays in payments or liquidity constraints or price uncertainty. Wherever it comes from the spread causes inefficiency of the market equilibrium. We discuss some institutions that can decrease the inefficiency. One is second currency (barter exchange in the inter-firm transactions. It is shown that the general equilibrium in an economy with second currency is effective though is still different from Arrow–Debreu equilibrium. Another solution can be introduction of mutual trade credit. In the economy with trade credit there are multiple equilibria that are more efficient than original bid-ask spread but still not as efficient as Arrow–Debreu one, too. The implications for firms' integration and applicability to Russian economy are discussed.

  13. Study of the Bulk Charge Carrier Dynamics in Anatase and Rutile TiO2 Single Crystals by Femtosecond Time Resolved Spectroscopy

    KAUST Repository

    Maity, Partha

    2018-04-02

    Understanding of the fundamentals behind charge carriers of photo-catalytic materials are still illusive hindering progress in our quest for renewable energy. TiO2 anatase and rutile are the most understood phases in photo-catalysis and serve as the best model for fundamental studies. Their ultrafast charge carrier dynamics especially on TiO2 anatase single crystal (the most active phase) are unresolved. Here femtosecond time resolved spectroscopy (TRS) was carried out to explore the dynamics of photo-excited charge carriers’ recombination in anatase single crystal, for the first time using pump fluence effects, and compares it to that of the rutile single crystal. A significant difference in charge carrier recombination rates between both crystals is observed. We found that the time constants for carrier recombination are two orders of magnitude slower for anatase (101) when compared to those of rutile (110). Moreover, bulk defects introduced by reduction of the samples via annealing in ultra-high vacuum resulted in faster recombination rates for both polymorphs. Both states (fresh and reduced) probed by pump fluence dependence measurements revealed that the major recombination channel in fresh and reduced anatase and reduced rutile is the first-order Shockley–Reed mediated. However, for fresh rutile, third-body Auger recombination was observed, attributed to the presence of higher density of intrinsic charge carriers. At all excitation wavelengths and fluence investigated, anatase (101) single crystal show longer charge carrier lifetime when compared to rutile (110) single. This may explain the superiority of the anatase phase for the electron transfer H+ reduction to molecular hydrogen.

  14. (Liquid + liquid) equilibria of perfluorocarbons with fluorinated ionic liquids

    International Nuclear Information System (INIS)

    Martinho, S.; Araújo, J.M.M.; Rebelo, L.P.N.; Pereiro, A.B.; Marrucho, I.M.

    2013-01-01

    Highlights: • (Liquid + liquid) equilibria perfluorocarbons and fluorinated ionic liquids. • Non-Random Two Liquid model was successfully applied. • Thermodynamic functions that describe the solvation process were calculated. -- Abstract: In order to evaluate the feasibility of partially replace perfluorocarbons (PFCs) with fluorinated ionic liquids (FILs) in PFCs-in-water emulsions, usually used for biomedical purposes, herein the (liquid + liquid) phase equilibria of FILs containing fluorinated chains longer than four carbons with PFCs were carried out in a wide range of temperatures. With this goal in mind, two PFCs (perfluorooctane and perfluorodecalin) were selected and the (liquid + liquid) equilibria of the binary mixtures of these PFCs and FILs were studied at atmospheric pressure in a temperature range from T (293.15 to 343.15) K. For these studies, FILs containing ammonium, pyridinium and imidazolium cations and different anions with fluorocarbon alkyl chains between 4 and 8 were included. Additionally, Non-Random Two Liquid (NRTL) thermodynamic model was successfully applied to correlate the behaviour of the PFCs + FILs binary mixtures. Moreover, thermodynamic functions that describe the solvation process were calculated from the experimental data

  15. Neoclassical MHD equilibria with ohmic current

    International Nuclear Information System (INIS)

    Tokuda, Shinji; Takeda, Tatsuoki; Okamoto, Masao.

    1989-01-01

    MHD equilibria of tokamak plasmas with neoclassical current effects (neoclassical conductivity and bootstrap current) were calculated self-consistently. Neoclassical effects on JFT-2M tokamak plasmas, sustained by ohmic currents, were studied. Bootstrap currents flow little for L-mode type equilibria because of low attainable values of poloidal beta, β J . H-mode type equilibria give bootstrap currents of 30% ohmic currents for β J attained by JFT-2M and 100% for β J ≥ 1.5, both of which are sufficient to change the current profiles and the resultant MHD equilibria. Neoclassical conductivity which has roughly half value of the classical Spitzer conductivity brings peaked ohmic current profiles to yield low safety factor at the magnetic axis. Neoclassical conductivity reduces the value of effective Z(Z eff ) which is necessary to give the observed one-turn voltage but it needs impurities accumulating at the center when such peaked current profiles are not observed. (author)

  16. Multiple equilibria in a simple elastocapillary system

    KAUST Repository

    Taroni, Michele; Vella, Dominic

    2012-01-01

    properties two stable equilibria may exist, and show via numerical solutions of the dynamic model that it is the initial state of the system that determines which stable equilibrium is ultimately reached. © 2012 Cambridge University Press.

  17. Evolution of secondary phases in 0.17C-16Cr-11Mn-0.43N austenitic stainless steel at 800 and 850°C: Thermodynamic modeling of phase equilibria and experimental kinetic studies

    Directory of Open Access Journals (Sweden)

    Čička R.

    2012-01-01

    Full Text Available The precipitation of secondary phases was investigated in the 0.17C-16Cr-11Mn-0.43N austenitic stainless steel during annealing at 800 and 850°C for times between 5 min and 100 h. Light microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, scanning electron microscopy, and differential thermal analysis were used in experiments. Thermodynamic calculations were done by the ThermoCalc database software package. Cr2N and M23C6 were considered to be stable phases at the annealing temperatures. Cells consisting of alternating Cr2N and austenite lamellae were observed in the steel microstructure after sufficiently long annealing. The metastable chi phase was also found in all the annealed samples. After 100 h of annealing the equilibrium sigma started to precipitate. The thermodynamically predicted M6C was not confirmed experimentally in any of the annealed samples. DTA analysis showed the initial precipitation stage was followed by the phase dissolution. For the investigated steel the computational thermodynamics can be used only for qualitative interpretation of the experimental results as the measured endothermal peaks were found to be shifted of about 50 ÷ 70°C related to the computed results.

  18. Preparation and characterization of phase-pure anatase and rutile TiO{sub 2} powder by new chemistry route; Preparacao e caracterizacao de nanoparticulas de TiO{sub 2} nas fases anatase e rutila por uma nova rota quimica

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, E. A.; Montanhera, M.A.; Paula, F.R., E-mail: sevlarede2@yahoo.com.br [Universidade Estadual Paulista Julio de Mesquista Filho (UNESP), Ilha Soltiera, SP (Brazil). Faculdade de Engenharia. Departameinto de Fisica e Quimica; Spada, E.R. [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Institutlo de Fisica

    2014-07-01

    Titanium dioxide (TiO{sub 2}) is used in a wire range applications such as photocatalysis and sensor device. In this work is shown a new and effective method for the preparation of TiO{sub 2} nanocrystalline in the crystallographic forms, anatase and rutile. The method involves dissolving the TiOSO{sub 4} powder in H{sub 2}O{sub 2} solution and thermal treatment of amorphous precipitate. The technique of X-ray diffraction was used to follow the structure evolution of amorphous precipitate. Pure anatase structure and rutile are obtained at 600 deg C and 1000 deg C with a grain size estimated 24 and 55 nm respectively. TiO{sub 2} nanoparticles is a promising alternative of the low cost whose potential for solar cells deserve a careful evaluation, especially in hybrid solar cells that employs TiO{sub 2} as electron acceptor and as transport channels. (author)

  19. A recipe for the use of rutile in sedimentary provenance analysis

    Science.gov (United States)

    Triebold, Silke; von Eynatten, Hilmar; Zack, Thomas

    2012-12-01

    Rutile has received considerable attention in the last decade as a valuable petrogenetic indicator mineral. Based on both new and previously published data, we carve out advantages and pitfalls regarding TiO2-minerals in sedimentary provenance analysis. This results in a recipe for the use of rutile in provenance studies. The main points are: Rutile geochemistry from different grain size fractions does not differ systematically, and hence rutiles should be extracted from the fraction containing the most rutile grains (usually 63-200 μm). Similarly, different magnetic susceptibility of rutile does not systematically imply different trace element composition. Before interpretation of TiO2-mineral data, it is important to determine the polymorph type. Rutile, anatase and brookite appear to differ systematically in trace element composition. As an alternative to Raman spectroscopy, chemical classification according to Nb, Cr, Sn, Fe, V, and Zr concentrations can be applied. For rutile, a new host lithology discrimination scheme based on Cr-Nb systematics is introduced (x = 5 ∗ (Nb [ppm] - 500) - Cr [ppm]), which leads to better classification results than previously published discrimination methods. According to this equation, metamafic rutiles have negative values of x, while metapelitic rutiles have positive values. Evaluation of the growth temperature calculations of metamorphic rutile after different authors shows that the equations given by Tomkins et al. (2007) should be applied to both metamafic and metapelitic rutiles. Although there is a pressure effect on the Zr incorporation in rutile, the pressure range for most rutiles of 5-15 kbar introduces an uncertainty in calculated temperature of no more than ± 35 °C. The distribution of calculated temperatures from detrital rutiles is crucial; only well-defined temperature populations should be used for thermometry interpretation.

  20. Preparation of rutile TiO(2) coating by thermal chemical vapor deposition for anticoking applications.

    Science.gov (United States)

    Tang, Shiyun; Wang, Jianli; Zhu, Quan; Chen, Yaoqiang; Li, Xiangyuan

    2014-10-08

    To inhibit the metal catalytic coking and improve the oxidation resistance of TiN coating, rutile TiO2 coating has been directly designed as an efficient anticoking coating for n-hexane pyrolysis. TiO2 coatings were prepared on the inner surface of SS304 tubes by a thermal CVD method under varied temperatures from 650 to 900 °C. The rutile TiO2 coating was obtained by annealing the as-deposited TiO2 coating, which is an alternative route for the deposition of rutile TiO2 coating. The morphology, elemental and phase composition of TiO2 coatings were characterized by SEM, EDX and XRD, respectively. The results show that deposition temperature of TiO2 coatings has a strong effect on the morphology and thickness of as-deposited TiO2 coatings. Fe, Cr and Ni at.% of the substrate gradually changes to 0 when the temperature is increased to 800 °C. The thickness of TiO2 coating is more than 6 μm and uniform by metalloscopy, and the films have a nonstoichiometric composition of Ti3O8 when the deposition temperature is above 800 °C. The anticoking tests show that the TiO2 coating at a deposition temperature of 800 °C is sufficiently thick to cover the cracks and gaps on the surface of blank substrate and cut off the catalytic coke growth effect of the metal substrate. The anticoking ratio of TiO2 coating corresponding to each 5 cm segments is above 65% and the average anticoking ratio of TiO2 coating is up to 76%. Thus, the TiO2 coating can provide a very good protective layer to prevent the substrate from severe coking efficiently.

  1. Ternary (liquid + liquid) equilibria of {trifluorotris(perfluoroethyl)phosphate based ionic liquids + thiophene + heptane}

    International Nuclear Information System (INIS)

    Marciniak, Andrzej; Królikowski, Marek

    2012-01-01

    Highlights: ► Ternary (liquid + liquid) equilibria for 3 ionic liquid + thiophene + heptane systems. ► The influence of ionic liquid structure on phase diagrams is discussed. ► High selectivity for separation of heptane/thiophene is observed. - Abstract: Ternary (liquid + liquid) equilibria for three systems containing ionic liquids {(4-(2-methoxyethyl)-4-methylmorpholinium trifluorotris(perfluoroethyl)phosphate, 1-(2-methoxyethyl)-1-methylpiperidinium trifluorotris(perfluoroethyl)phosphate, 1-(2-methoxyethyl)-1-methylpyrrolidinium trifluorotris(perfluoroethyl)phosphate) + thiophene + heptane} have been determined at T = 298.15 K. All systems showed high solubility of thiophene in the ionic liquid and low solubility of heptane. The solute distribution coefficient and the selectivity were calculated for all systems. High values of selectivity were obtained. The experimental results have been correlated using NRTL model. The influence of ionic liquid structure on phase equilibria is discussed.

  2. Effects of nano anatase-rutile TiO2 volume fraction with natural dye containing anthocyanin on the dye sensitized solar cell performance

    Science.gov (United States)

    Agustini, S.; Wahyuono, R. A.; Sawitri, D.; Risanti, D. D.

    2013-09-01

    Since its first development, efforts to improve efficiency of Dye Sensitized Solar Cell (DSSC) are continuously carried out, either through selection of dye materials, the type of semiconductor, counter electrode design or the sandwiched structure. It is widely known that anatase and rutile are phases of TiO2 that often being used for fabrication of DSSC. Rutile is thermodynamically more stable phase having band-gap suitable for absorption of sunlight spectrum. On the other hand, anatase has higher electrical conductivity, capability to adsorp dye as well as higher electron diffusion coefficient than those of rutile. Present research uses mangosteen pericarp and Rhoeo spathacea extracted in ethanol as natural dye containing anthocyanin. These dyes were characterized by using UV-Vis and FTIR, showing that the absorption maxima peaks obtained at 389 nm and 413 nm, for mangosteen and Rhoeo spathacea, respectively. The nano TiO2 was prepared by means of co-precipitation method. The particle size were 9-11 nm and 54.5 nm for anatase and rutile, respectively, according to Scherrer's equation. DSSCs were fabricated in various volume fractions of anatase and rutile TiO2. The fabricated DSSCs were tested under 17 mW/cm2 of solar irradiation. The current-voltage (I-V) characteristic of DSSCs employing 75%: 25% volume fraction of anatase and rutile TiO2 have outstanding result than others. The highest conversion efficiencies of 0.037% and 0.013% are obtained for DSSC employing natural dye extract from mangosteen pericarp and Rhoeo spathacea, respectively.

  3. Axisymmetric ideal magnetohydrodynamic equilibria with incompressible flows

    International Nuclear Information System (INIS)

    Tasso, H.; Throumoulopoulos, G.N.

    1997-12-01

    It is shown that the ideal MHD equilibrium states of an axisymmetric plasma with incompressible flows are governed by an elliptic partial differential equation for the poloidal magnetic flux function ψ containing five surface quantities along with a relation for the pressure. Exact equilibria are constructed including those with non vanishing poloidal and toroidal flows and differentially varying radial electric fields. Unlike the case in cylindrical incompressible equilibria with isothermal magnetic surfaces which should have necessarily circular cross sections [G. N. Throumoulopoulos and H. Tasso, Phys. Plasmas 4, 1492 (1997)], no restriction appears on the shapes of the magnetic surfaces in the corresponding axisymmetric equilibria. The latter equilibria satisfy a set of six ordinary differential equations which for flows parallel to the magnetic field B can be solved semianalytically. In addition, it is proved the non existence of incompressible axisymmetric equilibria with (a) purely poloidal flows and (b) non-parallel flows with isothermal magnetic surfaces and vertical stroke B vertical stroke = vertical stroke B vertical stroke (ψ) (omnigenous equilibria). (orig.)

  4. Surface energy effects on the stability of anatase and rutile nanocrystals: A predictive diagram for Nb_2O_5-doped-TiO_2

    International Nuclear Information System (INIS)

    Silva, Andre Luiz da; Hotza, Dachamir; Castro, Ricardo H.R.

    2017-01-01

    Highlights: • Anatase-rutile phase transition diagram was built for nano Nb_2O_5-doped-TiO_2. • Nb_2O_5-doping postpones the anatase-to-rutile transition. • The stability crossover for TiO_2 was 17.3 nm, for 2 mol% Nb_2O_5-doped-TiO_2 ∼30 nm. • The surface energy for Nb_2O_5-doped-TiO_2 decreases systematically with Nb concentration. - Abstract: Titanium dioxide nanoparticles are widely used for photocatalysis, and the relative fraction of titanium dioxide polymorph, i.e. anatase, rutile, or brookite, significantly affects the final performance. Even though conventional phase diagrams indicate a higher stability for the rutile polymorph, it is well established that nanosizes benefit the anatase phase due to its smaller surface energy. However, doping elements are expected to change this behavior, once changes in both surface and bulk energies may occur. Nb_2O_5 is commonly added to TiO_2 to allow property control. However, the effect of niobium on the relative stability of anatase and rutile phases is not well understood from the thermodynamic point of view. The objective of this work was to build a new predictive nanoscale phase diagram for Nb_2O_5-doped TiO_2. Water adsorption microcalorimetry and high temperature oxide melt solution were used to obtain the surface and bulk enthalpies. The phase diagram obtained shows the stable titania polymorph as a function of the composition and size.

  5. Study of paramagnetic defect centers in as-grown and annealed TiO2 anatase and rutile nanoparticles by a variable-temperature X-band and high-frequency (236 GHz) EPR.

    Science.gov (United States)

    Misra, S K; Andronenko, S I; Tipikin, D; Freed, J H; Somani, V; Prakash, Om

    2016-03-01

    Detailed EPR investigations on as-grown and annealed TiO 2 nanoparticles in the anatase and rutile phases were carried out at X-band (9.6 GHz) at 77, 120-300 K and at 236 GHz at 292 K. The analysis of EPR data for as-grown and annealed anatase and rutile samples revealed the presence of several paramagnetic centers: Ti 3+ , O - , adsorbed oxygen (O 2 - ) and oxygen vacancies. On the other hand, in as-grown rutile samples, there were observed EPR lines due to adsorbed oxygen (O 2 - ) and the Fe 3+ ions in both Ti 4+ substitutional positions, with and without coupling to an oxygen vacancy in the near neighborhood. Anatase nanoparticles were completely converted to rutile phase when annealed at 1000° C, exhibiting EPR spectra similar to those exhibited by the as-grown rutile nanoparticles. The high-frequency (236 GHz) EPR data on anatase and rutile samples, recorded in the region about g = 2.0 exhibit resolved EPR lines, due to O - and O 2 - ions enabling determination of their g-values with higher precision, as well as observation of hyperfine sextets due to Mn 2+ and Mn 4+ ions in anatase.

  6. The mantle source of island arc magmatism during early subduction: Evidence from Hf isotopes in rutile from the Jijal Complex (Kohistan arc, Pakistan)

    Science.gov (United States)

    Ewing, Tanya A.; Müntener, Othmar

    2018-05-01

    The Cretaceous-Paleogene Kohistan arc complex, northern Pakistan, is renowned as one of the most complete sections through a preserved paleo-island arc. The Jijal Complex represents a fragment of the plutonic roots of the Kohistan arc, formed during its early intraoceanic history. We present the first Hf isotope determinations for the Jijal Complex, made on rutile from garnet gabbros. These lithologies are zircon-free, but contain rutile that formed as an early phase. Recent developments in analytical capabilities coupled with a careful analytical and data reduction protocol allow the accurate determination of Hf isotope composition for rutile with <30 ppm Hf for the first time. Rutile from the analysed samples contains 5-35 ppm Hf, with sample averages of 13-17 ppm. Rutile from five samples from the Jijal Complex mafic section, sampling 2 km of former crustal thickness, gave indistinguishable Hf isotope compositions with εHf(i) ranging from 11.4 ± 3.2 to 20.1 ± 5.7. These values are within error of or only slightly more enriched than modern depleted mantle. The analysed samples record variable degrees of interaction with late-stage melt segregations, which produced symplectitic overprints on the main mineral assemblage as well as pegmatitic segregations of hydrous minerals. The indistinguishable εHf(i) across this range of lithologies demonstrates the robust preservation of the Hf isotope composition of rutile. The Hf isotope data, combined with previously published Nd isotope data for the Jijal Complex garnet gabbros, favour derivation from an inherently enriched, Indian Ocean type mantle. This implies a smaller contribution from subducted sediments than if the source was a normal (Pacific-type) depleted mantle. The Jijal Complex thus had only a limited recycled continental crustal component in its source, and represents a largely juvenile addition of new continental crust during the early phases of intraoceanic magmatism. The ability to determine the Hf

  7. Quantification of rutile in anatase by means of X-ray diffraction technique

    International Nuclear Information System (INIS)

    Macias B, L.R.; Palacios G, J.; Garcia C, R.M.

    1999-01-01

    In this work, making use of the X-ray diffraction technique, it was determined the quantification of two phases which are mixed in a crystalline sample of rutile and anatase also it is indicated the method to proceed in its evaluation, so that in the end it will be had as result of a semi-quantitative analysis of the phases that are found in the sample. The conclusion is that this method performs in samples which are presented as powders and since the different parameters with which they must be fulfilled then this should not be called quantitative but semi-quantitative and it has a margin of error in its evaluation. (Author)

  8. Assessment of solid/liquid equilibria in the (U, Zr)O

    NARCIS (Netherlands)

    Mastromarino, S.; Seibert, AF; Hashem, E.; Ciccioli, A.; Prieur, Damien; Scheinost, Andreas C.; Stohr, S.; Lajarge, P; Boshoven, JG; Robba, D.; Ernstberger, M; Bottomley, D.; Manara, D

    2017-01-01

    Solid/liquid equilibria in the system UO2–ZrO2 are revisited in this work by laser heating coupled with fast optical thermometry. Phase transition points newly measured under inert gas are in fair agreement with the early measurements performed by Wisnyi et al., in 1957, the

  9. High-voltage atmospheric breakdown across intervening rutile dielectrics.

    Energy Technology Data Exchange (ETDEWEB)

    Williamson, Kenneth Martin; Simpson, Sean; Coats, Rebecca Sue; Jorgenson, Roy Eberhardt; Hjalmarson, Harold Paul; Pasik, Michael Francis

    2013-09-01

    This report documents work conducted in FY13 on electrical discharge experiments performed to develop predictive computational models of the fundamental processes of surface breakdown in the vicinity of high-permittivity material interfaces. Further, experiments were conducted to determine if free carrier electrons could be excited into the conduction band thus lowering the effective breakdown voltage when UV photons (4.66 eV) from a high energy pulsed laser were incident on the rutile sample. This report documents the numerical approach, the experimental setup, and summarizes the data and simulations. Lastly, it describes the path forward and challenges that must be overcome in order to improve future experiments for characterizing the breakdown behavior for rutile.

  10. Low temperature N,N-dimethylformamide-assisted synthesis and characterization of anatase-rutile biphasic nanostructured titania

    Energy Technology Data Exchange (ETDEWEB)

    Estruga, M; Domenech, X; Ayllon, J A [Departament de Quimica, Universitat Autonoma de Barcelona, Campus UAB, E-08193 Bellaterra (Spain); Domingo, C [Institut de Ciencia dels Materials de Barcelona (CSIC), Campus UAB, E-08193 Bellaterra (Spain)], E-mail: joseantonio.ayllon@uab.es, E-mail: mestruga@qf.uab.cat

    2009-03-25

    Anatase and rutile biphasic nanostructured titania (TiO{sub 2}) has been synthesized via hydrolysis of titanium tetraisopropoxide in an aqueous solution of hydrobromic acid (HBr) and N,N-dimethylformamide (DMF) at 80 deg. C for 16 h. The presence of DMF, which was partially hydrolyzed during the process, determined the formation of a biphasic material. Powder x-ray diffraction showed the presence of both anatase and rutile titania phases in a ratio of approx. 1:1. Transmission electron microscope analysis showed that rutile was present as radial flower-like nanorods, which were surrounded by anatase spherical nanoparticles of 5 nm diameter. Low temperature nitrogen adsorption-desorption analysis showed the characteristic hysteresis loop of a mesoporous material. Specific surface area reached a value of 120 m{sup 2} g{sup -1} and the average pore diameter was 50 A. X-ray photoelectron spectroscopic analysis revealed that interstitial nitrogen was incorporated (0.35 at.%) during the annealing process. According to ultraviolet (UV)-visible diffuse reflectance spectroscope characterization, the N-doping caused a bandgap reduction from 3.0 to 2.9 eV. Photocatalytic activity of the material was tested for the degradation of methylene blue, methyl orange and 4-nitrophenol under near-UV and visible light radiation.

  11. Lattice defects in rutile, TiO2

    International Nuclear Information System (INIS)

    Nakagawa, M.; Itoh, H.; Nakanishi, S.; Kondo, K.; Okada, M.; Atobe, K.

    1991-01-01

    Rutile, TiO 2 , having a relatively high melting point exhibits strong optical absorption after neutron irradiation (8 x 10 16 n f /cm 2 ) at 15K. The band peak is located near 0.96 μ, having a FWHM of 0.87 eV (at liquid nitrogen temperature). After inverse recovery at 120K, lattice defects due probably to F centers are annealed out at about 220K. (author)

  12. On Equilibria of the Two-fluid Model in Magnetohydrodynamics

    International Nuclear Information System (INIS)

    Frantzeskakis, Dimitri J.; Stratis, Ioannis G.; Yannacopoulos, Athanasios N.

    2004-01-01

    We show how the equilibria of the two-fluid model in magnetohydrodynamics can be described by the double curl equation and through the study of this equation we study some properties of these equilibria

  13. Free-boundary perturbed MHD equilibria

    International Nuclear Information System (INIS)

    Nührenberg, C

    2012-01-01

    The concept of perturbed ideal MHD equilibria [Boozer A H and Nuhrenberg C 2006 Phys. Plasmas 13 102501] is employed to study the influence of external error-fields and of small plasma-pressure changes on toroidal plasma equilibria. In tokamak and stellarator free-boundary calculations, benchmarks were successful of the perturbed-equilibrium version of the CAS3D stability code [Nührenberg C et al. 2009 Phys. Rev. Lett. 102 235001] with the ideal MHD equilibrium code NEMEC [Hirshman S P et al. 1986 Comput. Phys. Commun. 43 143].

  14. Two-fluid equilibria with flow

    International Nuclear Information System (INIS)

    Steinhauer, L.

    1999-01-01

    The formalism is developed for flowing two-fluid equilibria. The equilibrium system is governed by a pair of second order partial differential equations for the magnetic stream function and the ion stream function plus a Bernoulli-like equation for the density. There are six arbitrary surface function. There are separate characteristic surfaces for each species, which are the guiding-center surfaces. This system is a generalization of the familiar Grad-Shafranov system for a single-fluid equilibrium without flow, which has only one equation and two arbitrary surface functions. In the case of minimum energy equilibria, the six surface functions take on particular forms. (author)

  15. Existence of pareto equilibria for multiobjective games without compactness

    OpenAIRE

    Shiraishi, Yuya; Kuroiwa, Daishi

    2013-01-01

    In this paper, we investigate the existence of Pareto and weak Pareto equilibria for multiobjective games without compactness. By employing an existence theorem of Pareto equilibria due to Yu and Yuan([10]), several existence theorems of Pareto and weak Pareto equilibria for the multiobjective games are established in a similar way to Flores-B´azan.

  16. Comparison of cation adsorption by isostructural rutile and cassiterite.

    Science.gov (United States)

    Machesky, Michael; Wesolowski, David; Rosenqvist, Jörgen; Předota, Milan; Vlcek, Lukas; Ridley, Moira; Kohli, Vaibhav; Zhang, Zhan; Fenter, Paul; Cummings, Peter; Lvov, Serguei; Fedkin, Mark; Rodriguez-Santiago, Victor; Kubicki, James; Bandura, Andrei

    2011-04-19

    Macroscopic net proton charging curves for powdered rutile and cassiterite specimens with the (110) crystal face predominant, as a function of pH in RbCl and NaCl solutions, trace SrCl(2) in NaCl, and trace ZnCl(2) in NaCl and Na Triflate solutions, are compared to corresponding molecular-level information obtained from static DFT optimizations and classical MD simulations, as well as synchrotron X-ray methods. The similarities and differences in the macroscopic charging behavior of rutile and cassiterite largely reflect the cation binding modes observed at the molecular level. Cation adsorption is primarily inner-sphere on both isostructural (110) surfaces, despite predictions that outer-sphere binding should predominate on low bulk dielectric constant oxides such as cassiterite (ε(bulk) ≈ 11). Inner-sphere adsorption is also significant for Rb(+) and Na(+) on neutral surfaces, whereas Cl(-) binding is predominately outer-sphere. As negative surface charge increases, relatively more Rb(+), Na(+), and especially Sr(2+) are bound in highly desolvated tetradentate fashion on the rutile (110) surface, largely accounting for enhanced negative charge development relative to cassiterite. Charging curves in the presence of Zn(2+) are very steep but similar for both oxides, reflective of Zn(2+) hydrolysis (and accompanying proton release) during the adsorption process, and the similar binding modes for ZnOH(+) on both surfaces. These results suggest that differences in cation adsorption between high and low bulk dielectric constant oxides are more subtly related to the relative degree of cation desolvation accompanying inner-sphere binding (i.e., more tetradentate binding on rutile), rather than distinct inner- and outer-sphere adsorption modes. Cation desolvation may be favored at the rutile (110) surface in part because inner-sphere water molecules are bound further from and less tightly than on the cassiterite (110) surface. Hence, their removal upon inner

  17. FP-LAPW Calculations of the EFG at Cd Impurities in Rutile SnO2

    International Nuclear Information System (INIS)

    Errico, L. A.; Fabricius, G.; Renteria, M.

    2001-01-01

    We report an ab initio study of the electric-field gradient (EFG) at Cd impurities located at the cation site in the semiconductor SnO 2 (rutile phase). The study was performed with the WIEN97 implementation of the FP-LAPW method. In order to simulate the diluted Cd-impurity in the SnO 2 host and to calculate the electronic structure of the system we used a 72-atoms super-cell, studying the relaxation introduced by the impurity in the lattice. The free-relaxation process performed shows that the relaxations of the oxygen nearest-neighbors of the impurity are not isotropic. Our prediction for the EFG tensor are compared with experimental results and point-charge model predictions

  18. Photodegradation of phenol by N-Doped TiO{sub 2} anatase/rutile nanorods assembled microsphere under UV and visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed, Mohamad Azuwa [Advanced Membrane Technology Research Centre, UniversitiTeknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Faculty of Petroleum and Renewable Energy Engineering, UniversitiTeknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Salleh, W.N.W., E-mail: hayati@petroleum.utm.my [Advanced Membrane Technology Research Centre, UniversitiTeknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Faculty of Petroleum and Renewable Energy Engineering, UniversitiTeknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Jaafar, Juhana; Ismail, A.F.; Nor, Nor Azureen Mohamad [Advanced Membrane Technology Research Centre, UniversitiTeknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Faculty of Petroleum and Renewable Energy Engineering, UniversitiTeknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia)

    2015-07-15

    N-doped TiO{sub 2} anatase/rutile nanorods assembled microspheres were successfully synthesized via a simple and direct sol–gel method containing titanium-n-butoxide Ti(OBu){sub 4} as a precursor material, nitric acid as a catalyst, and isopropanol as a solvent. By manipulating calcination temperature, the photocatalyst consisting of different phase compositions of anatase and rutile was obtained. The prepared TiO{sub 2} nanoparticles were characterized by means of x-ray diffraction (XRD), field emission scanning microscope (FESEM), atomic force microscopy (AFM), Brunauer–Emmett–Teller (BET) analysis, UV–Vis–NIR spectroscopy, and fourier transform infrared (FTIR). The results from UV–Vis–NIR spectroscopy and FTIR revealed the direct incorporation of nitrogen in TiO{sub 2} lattice since visible absorption capability was observed at 400–600 nm. XPS study indicated the incorporation of nitrogen as dopant in TiO{sub 2} at binding energies of 396.8, 397.5, 398.7, 399.8, and 401 eV. Calcination temperature was observed to have a great influence on the photocatalytic activity of the TiO{sub 2} nanorods. The photocatalytic activity of the prepared mixed phase of anatase/rutile TiO{sub 2} nanoparticles was measured by photodegradation phenol in an aqueous solution under UV and visible irradiations. N-doped TiO{sub 2} anatase/rutile nanorods assembled microsphere (consists of 38.3% anatase and 61.7% rutile) that was prepared at 400 °C exhibited the highest photocatalytic activity after irradiated under visible and UV light for 540 min. The high performance of photocatalyst materials could be obtained by adopting a judicious combination of anatase/rutile prepared at optimum calcination conditions. - Highlights: • Synthesis of N-Doped TiO{sub 2} Anatase/Rutile Nanorods via simple preparation method. • Direct incorporation of HNO{sub 3} as the nitrogen dopant source. • The photocatalytic properties were studied upon UV and visible light irradiation.

  19. Photodegradation of phenol by N-Doped TiO2 anatase/rutile nanorods assembled microsphere under UV and visible light irradiation

    International Nuclear Information System (INIS)

    Mohamed, Mohamad Azuwa; Salleh, W.N.W.; Jaafar, Juhana; Ismail, A.F.; Nor, Nor Azureen Mohamad

    2015-01-01

    N-doped TiO 2 anatase/rutile nanorods assembled microspheres were successfully synthesized via a simple and direct sol–gel method containing titanium-n-butoxide Ti(OBu) 4 as a precursor material, nitric acid as a catalyst, and isopropanol as a solvent. By manipulating calcination temperature, the photocatalyst consisting of different phase compositions of anatase and rutile was obtained. The prepared TiO 2 nanoparticles were characterized by means of x-ray diffraction (XRD), field emission scanning microscope (FESEM), atomic force microscopy (AFM), Brunauer–Emmett–Teller (BET) analysis, UV–Vis–NIR spectroscopy, and fourier transform infrared (FTIR). The results from UV–Vis–NIR spectroscopy and FTIR revealed the direct incorporation of nitrogen in TiO 2 lattice since visible absorption capability was observed at 400–600 nm. XPS study indicated the incorporation of nitrogen as dopant in TiO 2 at binding energies of 396.8, 397.5, 398.7, 399.8, and 401 eV. Calcination temperature was observed to have a great influence on the photocatalytic activity of the TiO 2 nanorods. The photocatalytic activity of the prepared mixed phase of anatase/rutile TiO 2 nanoparticles was measured by photodegradation phenol in an aqueous solution under UV and visible irradiations. N-doped TiO 2 anatase/rutile nanorods assembled microsphere (consists of 38.3% anatase and 61.7% rutile) that was prepared at 400 °C exhibited the highest photocatalytic activity after irradiated under visible and UV light for 540 min. The high performance of photocatalyst materials could be obtained by adopting a judicious combination of anatase/rutile prepared at optimum calcination conditions. - Highlights: • Synthesis of N-Doped TiO 2 Anatase/Rutile Nanorods via simple preparation method. • Direct incorporation of HNO 3 as the nitrogen dopant source. • The photocatalytic properties were studied upon UV and visible light irradiation. • The optimum calcination temperature is 400 °C for

  20. Ideal MHD stability of high poloidal beta equilibria in TFTR

    International Nuclear Information System (INIS)

    Sabbagh, S.A.; Mauel, M.E.; Navratil, G.A.; Bell, M.G.; Budny, R.V.; Chance, M.S.; Fredrickson, E.D.; Jardin, S.C.; Manickam, J.; McCune, D.C.; McGuire, K.M.; Wieland, R.M.; Zarnstorff, M.C.; Phillips, M.W.; Hughes, M.H.; Kesner, J.

    1991-01-01

    Recent experiments in TFTR have expanded the operating space of the device to include plasmas with values of var-epsilon β p dia ≡ 2μ 0 var-epsilon perpendicular >/ p >> 2 as large as 1.6, and Troyon normalized diamagnetic beta β N dia ≡ β t perpendicular aB t /10 -8 I p as large as 4.7. At values of var-epsilon β p dia ≥ 1.3, a separatrix was observed to enter the vacuum vessel, producing a naturally diverted discharge. Plasmas with large values of var-epsilon β p dia were created with both the plasma current, I p , held constant and with I p decreased, or ramped down, before the start of neutral beam injection. A convenient characterization of the change in I p using experimental parameters can be defined by the ratio of I p before the ramp down, to I p during the neutral beam heating phase, F I p . The ideal MHD stability of these equilibria is investigated to determine their location in stability space, and to study the role of plasma current and pressure profile modification in the creation of these high var-epsilon β p and β N plasmas. The evolution of these plasmas is modelled from experimental data using the TRANSP code. Two-dimensional equilibria are computed from the TRANSP results and used as input to both high and low-n stability codes including PEST. The high var-epsilon β p equilibria, which generally have an oblate cross-sectional shape, are in the first stability region to high-n ballooning modes. At constant I p , these equilibria generally have maximum pressure gradients near the magnetic axis and are stable to n=1 modes without a stabilizing conducting wall. The effect of the current profile shape on the stability of low-n kink/ballooning modes and the requirements for these plasmas to access the second stability region are examined. 6 refs

  1. MHD stability of vertically asymmetric tokamak equilibria

    International Nuclear Information System (INIS)

    Dalhed, H.E.; Grimm, R.C.; Johnson, J.L.

    1981-03-01

    The ideal MHD stability properties of a special class of vertically asymmetric tokamak equilibria are examined. The calculations confirm that no major new physical effects are introduced and the modifications can be understood by conventional arguments. The results indicate that significant departures from up-down symmetry can be tolerated before the reduction in β becomes important for reactor operation

  2. Nash equilibria via duality and homological selection

    Indian Academy of Sciences (India)

    1Quantitative Methods and Information Systems Area, Indian Institute ... The original proof of existence of Nash equilibria [13] uses fairly ...... The fiber over a regular point a of the disk Di consists of three inverse images (labeled. A1,A2,A3 in ...

  3. Equilibrator: Modeling Chemical Equilibria with Excel

    Science.gov (United States)

    Vander Griend, Douglas A.

    2011-01-01

    Equilibrator is a Microsoft Excel program for learning about chemical equilibria through modeling, similar in function to EQS4WIN, which is no longer supported and does not work well with newer Windows operating systems. Similar to EQS4WIN, Equilibrator allows the user to define a system with temperature, initial moles, and then either total…

  4. Computation of tokamak equilibria with steady flow

    International Nuclear Information System (INIS)

    Kerner, W.; Tokuda, Shinji

    1987-08-01

    The equations for ideal MHD equilibria with stationary flow are reexamined and addressed as numerically applied to tokamak configurations with a free plasma boundary. Both the isothermal (purely toroidal flow) and the poloidal flow cases are treated. Experiment-relevant states with steady flow (so far only in the toroidal direction) are computed by the modified SELENE40 code. (author)

  5. On the stability of dissipative MHD equilibria

    International Nuclear Information System (INIS)

    Teichmann, J.

    1979-04-01

    The global stability of stationary equilibria of dissipative MHD is studied uisng the direct Liapunov method. Sufficient and necessary conditions for stability of the linearized Euler-Lagrangian system with the full dissipative operators are given. The case of the two-fluid isentropic flow is discussed. (orig.)

  6. Intermediates and Generic Convergence to Equilibria

    DEFF Research Database (Denmark)

    Marcondes de Freitas, Michael; Wiuf, Carsten; Feliu, Elisenda

    2017-01-01

    Known graphical conditions for the generic and global convergence to equilibria of the dynamical system arising from a reaction network are shown to be invariant under the so-called successive removal of intermediates, a systematic procedure to simplify the network, making the graphical conditions...

  7. On the stochastic stability of MHD equilibria

    International Nuclear Information System (INIS)

    Teichmann, J.

    1979-07-01

    The stochastic stability in the large of stationary equilibria of ideal and dissipative magnetohydrodynamics under the influence of stationary random fluctuations is studied using the direct Liapunov method. Sufficient and necessary conditions for stability of the linearized Euler-Lagrangian systems are given. The destabilizing effect of stochastic fluctuations is demonstrated. (orig.)

  8. Anatase/rutile TiO2 composites: Influence of the mixing ratio on the photocatalytic degradation of Malachite Green and Orange II in slurry

    International Nuclear Information System (INIS)

    Bojinova, A.; Kralchevska, R.; Poulios, I.; Dushkin, C.

    2007-01-01

    The present study is directed to clarify the influence of the ratio of anatase to rutile phase, containing in the TiO 2 samples, on their activity as photocatalysts in slurry. A series of samples corresponding to different percentages of anatase is prepared from commercial anatase and rutile TiO 2 brands (KRONOS). The crystalline phase composition of the samples is characterized by X-ray diffraction. The photocatalytic action of the mixtures is tested in photodegradation of the commercial organic dyes Malachite Green Hydrochloride and Orange II in aqueous solutions under UV irradiation. Comparative tests with Degussa P-25 are performed. The apparent rate constants of the process are determined from the kinetic curves using appropriate models. They generally increase with the anatase ratio, being always larger for Malachite Green than for Orange II

  9. A thick hierarchical rutile TiO2 nanomaterial with multilayered structure

    International Nuclear Information System (INIS)

    Zhu, Shengli; Xie, Guoqiang; Yang, Xianjin; Cui, Zhenduo

    2013-01-01

    Highlights: ► We synthesized a new rutile TiO 2 nanomaterial with a hierarchical nanostructure. ► The nano architecture structure consist of nanorods and nanoflower arrays. ► The rutile TiO 2 nanomaterial is thick in size (several 10 μm). ► The TiO 2 nanomaterials present a multilayer structure. - Abstract: In the present paper, we synthesized a new type of rutile TiO 2 nanomaterial with a hierarchical nanostructure using a novel method, which combined dealloying process with chemical synthesis. The structure characters were examined using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The rutile TiO 2 nanomaterial is thick in size (several 10 μm). The hierarchical structure of the rutile TiO 2 nanomaterial consists of large quantities nanorods and nanoflower arrays. The nanoflowers consist of serveral nanopetals with diameter of 100–200 nm. The cross section of TiO 2 nanomaterials presents a multilayer structure with the layer thickness of about 3–5 μm. The rutile TiO 2 nanomaterial has high specific surface area. The formation mechanism of the rutile TiO 2 nanomaterial was discussed according to the experimental results. The rutile TiO 2 nanomaterial has potential applications in catalysis, photocatalysis and solar cells

  10. Description of gas hydrates equilibria in sediments using experimental data of soil water potential

    Energy Technology Data Exchange (ETDEWEB)

    Istomin, V. [NOVATEK, Moscow (Russian Federation); Chuvilin, E. [Moscow State Univ., Moscow (Russian Federation). Dept. of Geology; Makhonina, N.; Kvon, V. [VNIIGAZ, Moscow (Russian Federation); Safonov, S. [Schlumberger Moscow Research, Moscow (Russian Federation)

    2008-07-01

    Analytical relationships have been developed between hydrate dissociation pressure and vapor pressure above the pore water surface. In addition, experiments have been discussed in numerous publications on the effect of narrow interconnected throats between pores on clathrate dissociation conditions in porous media. This paper presented an approach that improved upon the available thermodynamic methods for calculation of hydrate phase equilibria. The approach took into account the properties of pore water in natural sediments including three-phase equilibrium of gas-pore water-gas hydrate in a similar way as for unfrozen water in geocryology science. The purpose of the paper was to apply and adapt geocryology and soil physics method to the thermodynamic calculation of non-clathrated water content in sediments. It answered the question of how to estimate the non-clathrated water content if pore water potential was known. The paper explained the thermodynamics of water phase in porous media including the thermodynamic properties of supercooled water, the thermodynamic properties of pore water and pore ice in sediments, and the phase equilibria of pore water. The paper also discussed the quantitative techniques that were utilized for determination of unfrozen water content in sediments and its dependence on temperature variation. These included contact-saturation, calorimetric, dielectric, nuclear magnetic resonance, and others. The thermodynamic calculations of pore water phase equilibria were also presented. 30 refs., 5 tabs., 8 figs.

  11. Effect of rutile TiO{sub 2} on the photocatalytic performance of g-C{sub 3}N{sub 4}/brookite-TiO{sub 2-x}N{sub y} photocatalyst for NO decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Li, Huihui, E-mail: lihh@lzu.edu.cn [Key Laboratory for Magnetism Magnetic Materials of the Ministry of Education, Lanzhou University, 222 south Tianshui Road, Lanzhou, 730000 (China); Wu, Xiaoyong [Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China); Yin, Shu [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Katsumata, Kenichi [Photocatalysis International Research Center, Research Institute for Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba, 278-8510 (Japan); Wang, Yuhua [Key Laboratory for Magnetism Magnetic Materials of the Ministry of Education, Lanzhou University, 222 south Tianshui Road, Lanzhou, 730000 (China)

    2017-01-15

    Graphical abstract: g-C{sub 3}N{sub 4}/rutile-brookite TiO{sub 2-x}Ny forms a Z-scheme photocatalytic system, which shows improvement on the photocatalytic activity than that of g-C{sub 3}N{sub 4}/single brookite TiO{sub 2-x}N{sub y}. - Highlights: • g-C{sub 3}N{sub 4}/rutile-brookite TiO{sub 2-x}N{sub y} forms a Z-scheme photocatalytic system. • Photogenerated electrons can efficiently transfer from rutile TiO{sub 2} to g-C{sub 3}N{sub 4}. • Single brookite TiO{sub 2-x}N{sub y} shows lower photo-utilization efficiency than rutile-brookite mixed one. • DeNO{sub x} activities of brookite TiO{sub 2-x}N{sub y} hybrids decrease with g-C{sub 3}N{sub 4} amount increase. - Abstract: Novel g-C{sub 3}N{sub 4}/rutile-brookite TiO{sub 2-x}N{sub y} composite photocatalysts were fabricated through a facile solvothermal approach. The effect of rutile phase TiO{sub 2} with brookite TiO{sub 2} and g-C{sub 3}N{sub 4} on the photocatalytic activity of g-C{sub 3}N{sub 4}/nitrogen-doped TiO{sub 2} composite was studied. The photocatalytic performance of the photocatalyst was evaluated by measuring the degradation of NO gas under visible and UV light irradiation. It is suggested that g-C{sub 3}N{sub 4}/rutile-brookite TiO{sub 2-x}N{sub y} forms a Z-scheme photocatalytic system, which shows improvement on the photocatalytic activity than that of g-C{sub 3}N{sub 4}/single brookite TiO{sub 2-x}N{sub y}. By importing rutile phase TiO{sub 2-x}N{sub y}, the photogenerated electrons can efficiently transfer from rutile TiO{sub 2} to g-C{sub 3}N{sub 4}, which results in the separation of electron and hole pairs, enhancing the photocatalytic ability. However, single brookite TiO{sub 2-x}N{sub y} can not remove the photogenerated electrons efficiently and the photocatalytic performances of composites decrease with g-C{sub 3}N{sub 4} amount increase.

  12. Effect of temperature on acid–base equilibria in separation techniques. A review

    International Nuclear Information System (INIS)

    Gagliardi, Leonardo G.; Tascon, Marcos; Castells, Cecilia B.

    2015-01-01

    Studies on the theoretical principles of acid–base equilibria are reviewed and the influence of temperature on secondary chemical equilibria within the context of separation techniques, in water and also in aqueous-organic solvent mixtures, is discussed. In order to define the relationships between the retention in liquid chromatography or the migration velocity in capillary electrophoresis and temperature, the main properties of acid–base equilibria have to be taken into account for both, the analytes and the conjugate pairs chosen to control the solution pH. The focus of this review is based on liquid–liquid extraction (LLE), liquid chromatography (LC) and capillary electrophoresis (CE), with emphasis on the use of temperature as a useful variable to modify selectivity on a predictable basis. Simplified models were evaluated to achieve practical optimizations involving pH and temperature (in LLE and CE) as well as solvent composition in reversed-phase LC. - Highlights: • The study of theoretical principles of acid–base equilibrium has been reviewed. • The proton transfer process is often present in the analytical separation practice. • The influence of temperature on secondary chemical equilibria is examined. • The focus is laid on liquid chromatography and capillary electrophoresis. • Temperature can be a useful variable to modify selectivity under predictable basis

  13. Gyrokinetic magnetohydrodynamics and the associated equilibria

    Science.gov (United States)

    Lee, W. W.; Hudson, S. R.; Ma, C. H.

    2017-12-01

    The gyrokinetic magnetohydrodynamic (MHD) equations, related to the recent paper by W. W. Lee ["Magnetohydrodynamics for collisionless plasmas from the gyrokinetic perspective," Phys. Plasmas 23, 070705 (2016)], and their associated equilibria properties are discussed. This set of equations consists of the time-dependent gyrokinetic vorticity equation, the gyrokinetic parallel Ohm's law, and the gyrokinetic Ampere's law as well as the equations of state, which are expressed in terms of the electrostatic potential, ϕ, and the vector potential, A , and support both spatially varying perpendicular and parallel pressure gradients and the associated currents. The corresponding gyrokinetic MHD equilibria can be reached when ϕ→0 and A becomes constant in time, which, in turn, gives ∇.(J∥+J⊥)=0 and the associated magnetic islands, if they exist. Examples of simple cylindrical geometry are given. These gyrokinetic MHD equations look quite different from the conventional MHD equations, and their comparisons will be an interesting topic in the future.

  14. Multiple equilibria in a simple elastocapillary system

    KAUST Repository

    Taroni, Michele

    2012-09-28

    We consider the elastocapillary interaction of a liquid drop placed between two elastic beams, which are both clamped at one end to a rigid substrate. This is a simple model system relevant to the problem of surface-tension-induced collapse of flexible micro-channels that has been observed in the manufacture of microelectromechanical systems (MEMS). We determine the conditions under which the beams remain separated, touch at a point, or stick along a portion of their length. Surprisingly, we show that in many circumstances multiple equilibrium states are possible. We develop a lubrication-type model for the flow of liquid out of equilibrium and thereby investigate the stability of the multiple equilibria. We demonstrate that for given material properties two stable equilibria may exist, and show via numerical solutions of the dynamic model that it is the initial state of the system that determines which stable equilibrium is ultimately reached. © 2012 Cambridge University Press.

  15. Dynamic data evaluation for solid-liquid equilibria

    DEFF Research Database (Denmark)

    Cunico, Larissa; Ceriani, Roberta; Kang, Jeong Won

    The accuracy and reliability of the measured data sets to be used in regression of model parameters is an important issue related to modeling of phase equilibria. It is clear that good parameters for any model cannot be obtained from low quality data. A thermodynamic consistency test for solid...... and parameter regression. The paper will highlight the data collection, the data analysis for SLE data and the thermodynamic model performance (such as NRTL, UNIQUAC and original UNIFAC)....... studies considering the methodology proposed for SLE thermodynamic consistency tests and data from open literature and databases such as NIST-TDE®, DIPPR® and DECHEMA® are presented. The SLE consistency test and data evaluation is performed in a software containing option for data analysis, model analysis...

  16. A new transiently chaotic flow with ellipsoid equilibria

    Science.gov (United States)

    Panahi, Shirin; Aram, Zainab; Jafari, Sajad; Pham, Viet-Thanh; Volos, Christos; Rajagopal, Karthikeyan

    2018-03-01

    In this article, a simple autonomous transiently chaotic flow with cubic nonlinearities is proposed. This system represents some unusual features such as having a surface of equilibria. We shall describe some dynamical properties and behaviours of this system in terms of eigenvalue structures, bifurcation diagrams, time series, and phase portraits. Various behaviours of this system such as periodic and transiently chaotic dynamics can be shown by setting special parameters in proper values. Our system belongs to a newly introduced category of transiently chaotic systems: systems with hidden attractors. Transiently chaotic behaviour of our proposed system has been implemented and tested by the OrCAD-PSpise software. We have found a proper qualitative similarity between circuit and simulation results.

  17. A series of three-dimensional lanthanide coordination polymers with rutile and unprecedented rutile-related topologies.

    Science.gov (United States)

    Qin, Chao; Wang, Xin-Long; Wang, En-Bo; Su, Zhong-Min

    2005-10-03

    The complexes of formulas Ln(pydc)(Hpydc) (Ln = Sm (1), Eu (2), Gd (3); H2pydc = pyridine-2,5-dicarboxylic acid) and Ln(pydc)(bc)(H2O) (Ln = Sm (4), Gd (5); Hbc = benzenecarboxylic acid) have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR, TG analysis, and single-crystal X-ray diffraction. Compounds 1-3 are isomorphous and crystallize in the orthorhombic system, space group Pbcn. Their final three-dimensional racemic frameworks can be considered as being constructed by helix-linked scalelike sheets. Compounds 4 and 5 are isostructural and crystallize in the monoclinic system, space group P2(1)/c. pydc ligands bridge dinuclear lanthanide centers to form the three-dimensional frameworks featuring hexagonal channels along the a-axis that are occupied by one-end-coordinated bc ligands. From the topological point of view, the five three-dimensional nets are binodal with six- and three-connected nodes, the former of which exhibit a rutile-related (4.6(2))(2)(4(2).6(9).8(4)) topology that is unprecedented within coordination frames, and the latter two species display a distorted rutile (4.6(2))(2)(4(2).6(10).8(3)) topology. Furthermore, the luminescent properties of 2 were studied.

  18. Prediction of vapour-liquid equilibria for the kinetic study of processes based on synthesis gas

    Energy Technology Data Exchange (ETDEWEB)

    Di Serio, M.; Tesser, R.; Cozzolino, M.; Santacesaria, E. [Naples Univ., Napoli (Italy). Dept. of Chemistry

    2006-07-01

    Syngas is normally used in the production of a broad range of chemicals and fuels. In many of these processes multiphase reactors, gas-liquid or gas-liquid-solid are used. Kinetic studies in multiphase systems are often complicated by the non-ideal behaviour of reagents and/or products that are consistently partitioned between the liquid and the vapour phase. Moreover, as often kinetic data are collected in batch conditions for the liquid phase, activity coefficients of the partitioned components can consistently change during the time as a consequence of changing the composition of the reaction mixture. Therefore, it is necessary, in these cases, to known the vapor-liquid equilibria (VLE) in order to collect and to interpret correctly the kinetic data. The description of phase equilibria, at high pressures, is usually performed by means of an EOS (Equation of State) allowing the calculation of fugacity coefficients, for each component, in both phases and determining the partition coefficients but the EOS approach involves the experimental determination of the interaction parameters for all the possible binary system of the mixture. For multicomponent mixtures a complete experimental determination of vapourliquid equilibria is very hard, also considering the high pressure and temperatures used. Some predictive group contribution methods have been recently developed. In this paper, we will describe in detail the application of these methods to the methanol homologation, as an example, with the scope of determining more reliable kinetic parameters for this reaction. (orig.)

  19. Uniqueness of Nash equilibria in a quantum Cournot duopoly game

    International Nuclear Information System (INIS)

    Sekiguchi, Yohei; Sakahara, Kiri; Sato, Takashi

    2010-01-01

    A quantum Cournot game whose classical form game has multiple Nash equilibria is examined. Although the classical equilibria fail to be Pareto optimal, the quantum equilibrium exhibits the following two properties: (i) if the measurement of entanglement between strategic variables chosen by the competing firms is sufficiently large, the multiplicity of equilibria vanishes, and (ii) the more strongly the strategic variables are entangled, the more closely the unique equilibrium approaches to the optimal one.

  20. (Solid + liquid) phase equilibria of (Ca(H2PO2)2 + CaCl2 + H2O) and (Ca(H2PO2)2 + NaH2PO2 + H2O) ternary systems at T = 323.15 K

    International Nuclear Information System (INIS)

    Cao, Hong-yu; Zhou, Huan; Bai, Xiao-qin; Ma, Ruo-xin; Tan, Li-na; Wang, Jun-min

    2016-01-01

    Graphical abstract: Solubility diagram of the (Ca(H 2 PO 2 ) 2 + NaH 2 PO 2 + H 2 O) system at T = (323.15 and 298.15) K. - Highlights: • Phase diagrams of Ca 2+ -H 2 PO 2 − -Cl − -H 2 O, Ca 2+ -Na + -H 2 PO 2 − -H 2 O at 323.15 K were obtained. • Incompatible double salt of NaCa(H 2 PO 2 ) 3 in Ca 2+ -Na + -H 2 PO 2 − -H 2 O system was determined. • Density diagram of the corresponding liquid were simultaneously measured. - Abstract: Calcium hypophosphite has been widely used as an anti-corrosive agent, flame retardant, fertilizer, assistant for Ni electroless plating, and animal nutritional supplement. High purity calcium hypophosphite can be synthesized via the replacement reaction of sodium hypophosphite and calcium chloride. In this work, the (solid + liquid) phase equilibria of (Ca(H 2 PO 2 ) 2 + CaCl 2 + H 2 O) and (Ca(H 2 PO 2 ) 2 + NaH 2 PO 2 + H 2 O) ternary systems at T = 323.15 K were studied experimentally via the classical isothermal solubility equilibrium method, and the phase diagrams for these two systems were obtained. It was found that two solid salts of CaCl 2 ·2H 2 O and Ca(H 2 PO 2 ) 2 exist in the (Ca(H 2 PO 2 ) 2 + CaCl 2 + H 2 O) system, and three salts of Ca(H 2 PO 2 ) 2 , NaH 2 PO 2 ·H 2 O and one incompatible double salt, NaCa(H 2 PO 2 ) 3 occur in the (Ca(H 2 PO 2 ) 2 + NaH 2 PO 2 + H 2 O) system.

  1. Room temperature ferromagnetism of iron-doped rutile TiO{sub 2} nanorods synthesized by a low temperature method

    Energy Technology Data Exchange (ETDEWEB)

    Melghit, Khaled [Chemistry Department, College of Science, Sultan Qaboos University, P.O. Box 36, Al-Khodh 123 (Oman)], E-mail: melghit@squ.edu.om; Bouziane, Khalid [Physics Department, College of Science, Sultan Qaboos University, P.O. Box 36, Al-Khodh 123 (Oman)

    2008-04-03

    Nanorods of Fe-TiO{sub 2} were synthesized at 100 deg. C and room pressure by mixing titanium oxide wet gel TiO{sub 2}.xH{sub 2}O with a boiling solution of iron nitrate. The results of EDAX, performed on different selected area of the sample, revealed a homogeneous composition of about 3 at% Fe. Electron diffraction and XRD measurements show that the as-prepared Fe-TiO{sub 2} and annealed one at 550 deg. C have both a single rutile structure with no indication about the presence of a secondary phase. The transmission electron microscopy (TEM) micrographs show that both as-prepared Fe-TiO{sub 2} and annealed one at 550 deg. C have nanorod-shape with dimensions length by diameter of about 60 x 5 nm and 52 x 12 nm, respectively. Magnetization measurements show that both samples present a nonzero remanence and a coercivity of 108 and 120 Oe, respectively. At higher temperature, 850 deg. C, Fe-TiO{sub 2} decomposes to rutile TiO{sub 2} and new iron-titanate phase.

  2. Electric-dipole effect of defects on the energy band alignment of rutile and anatase TiO₂.

    Science.gov (United States)

    Zhang, Daoyu; Yang, Minnan; Dong, Shuai

    2015-11-21

    Titanium dioxide materials have been studied intensively and extensively for photocatalytic applications. A long-standing open question is the energy band alignment of rutile and anatase TiO2 phases, which can affect the photocatalytic process in the composite system. There are basically two contradictory viewpoints about the alignment of these two TiO2 phases supported by the respective experiments: (1) straddling type and (2) staggered type. In this work, our DFT plus U calculations show that the perfect rutile(110) and anatase(101) surfaces have the straddling type band alignment, whereas the surfaces with defects can turn the band alignment into the staggered type. The electric dipoles induced by defects are responsible for the reversal of band alignment. Thus the defects introduced during the preparation and post-treatment processes of materials are probably the answer to the above open question regarding the band alignment, which can be considered in real practice to tune the photocatalytic activity of materials.

  3. Highly flexible self-standing film electrode composed of mesoporous rutile TiO2/C nanofibers for lithium-ion batteries

    International Nuclear Information System (INIS)

    Zhao Bote; Cai Rui; Jiang Simin; Sha Yujing; Shao Zongping

    2012-01-01

    There is increasing interest in flexible, safe, high-power thin-film lithium-ion batteries which can be applied to various modern devices. Although TiO 2 in rutile phase is highly attractive as an anode material of lithium-ion batteries for its high thermal stability and theoretical capacity of 336 mA h g −1 and low price, its inflexibility and sluggish lithium intercalation kinetics of bulk phase strongly limit its practical application for particular in thin-film electrode. Here we show a simple way to prepare highly flexible self-standing thin-film electrodes composed of mesoporous rutile TiO 2 /C nanofibers with low carbon content ( 2 in as-fabricated nanofibers. Big size (10 cm × 4 cm), flexible thin film is obtained after heat treatment under 10%H 2 –Ar at 900 °C for 3 h. After optimization, the diameter of fibers can reach as small as ∼110 nm, and the as-prepared rutile TiO 2 films show high initial electrochemical activity with the first discharge capacity as high as 388 mA h g −1 . What is more, very stable reversible capacities of ∼122, 92, and 70 mA h g −1 are achieved respectively at 1, 5 and 10 C rates with negligible decay rate within 100 cycling times.

  4. Ternary (liquid + liquid) equilibria of {bis(trifluoromethylsulfonyl)-amide based ionic liquids + butan-1-ol + water}

    International Nuclear Information System (INIS)

    Marciniak, Andrzej; Wlazło, Michał; Gawkowska, Joanna

    2016-01-01

    Highlights: • Ternary (liquid + liquid) equilibria for 3 ionic liquid + butanol + water systems. • The influence of ionic liquid structure on phase diagrams is discussed. • Influence of IL structure on S and β for butanol/water separation is discussed. - Abstract: Ternary (liquid + liquid) phase equilibria for 3 systems containing bis(trifluoromethylsulfonyl)-amide ionic liquids (1-buthyl-1-methylpiperidinium bis(trifluoromethylsulfonyl)-amide, 1-(2-methoxyethyl)-1-methylpiperidinium bis(trifluoromethylsulfonyl)-amide, {1-(2-methoxyethyl)-1-methylpyrrolidinium bis(trifluorylsulfonyl)-amide) + butan-1-ol + water} have been determined at T = 298.15 K. The selectivity and solute distribution ratio were calculated for investigated systems and compared with literature data for other systems containing ionic liquids. In each system total solubility of butan-1-ol and low solubility of water in the ionic liquid is observed. The experimental results have been correlated using NRTL model. The influence of the structure of ionic liquid on phase equilibria, selectivity and solute distribution ratio is shortly discussed.

  5. The behavior of mineral inclusions during host decomposition. A SEM-STEM study of rutile inclusions at a natural propagating corundum-spinel interface.

    Science.gov (United States)

    Baldwin, Lisa; Li, Chen; Habler, Gerlinde; Abart, Rainer

    2017-04-01

    When two neighbor phases are not in chemical equilibrium, they may react and produce a reaction rim at their interface, separating the mutually incompatible phases. At constant P-T-X conditions, such a reaction will continue until one of the reactants is completely consumed. Reaction rim growth involves transfer of chemical components across the growing rim by long-range diffusion and localized interface reactions on either side of the growing rim. Consequently, the thickness of the reaction rim will be a function of time. Yet, in order to quantify and interpret such corona structures and to define a reaction rate law, the kinetics and mechanism of rim formation must be well constrained. In particular, the coupling between long-range diffusion, and interface reaction must be known. In this contribution we focus on potential complexities associated with interface reactions. Many natural minerals contain inclusions of other phases, which in turn may influence the reaction interface propagation kinetics during host phase decomposition (Ashby et al. 1969), as a propagating reaction interface dissipates more free energy when bypassing a mineral inclusion, resulting in a locally decelerated reaction rate. Here, we report results of a SEM-STEM study of the interface between natural rutile-bearing corundum and a polycrystalline ferromagnesio-aluminate spinel that grew topotactically with respect to the corundum precursor as a consequence of its reaction with FeO and MgO from basaltic melt. Electron Backscatter Diffraction (EBSD) crystal orientation imaging revealed that the spinel rim is polycrystalline and exhibits (111) twinning that is parallel to the corundum (0001) plane. The rutile inclusions in corundum are elongated perpendicular to the corundum [0001] axis and are randomly oriented in the (0001) plane. Furthermore, they follow an oscillatory grain size distribution zonation with grain sizes being either a few tens of nanometers, or about 500 to 800 nanometers in

  6. Exogenous empirical-evidence equilibria in perfect-monitoring repeated games yield correlated equilibria

    KAUST Repository

    Dudebout, Nicolas; Shamma, Jeff S.

    2014-01-01

    This paper proves that exogenous empirical-evidence equilibria (xEEEs) in perfect-monitoring repeated games induce correlated equilibria of the associated one-shot game. An empirical-evidence equilibrium (EEE) is a solution concept for stochastic games. At equilibrium, agents' strategies are optimal with respect to models of their opponents. These models satisfy a consistency condition with respect to the actual behavior of the opponents. As such, EEEs replace the full-rationality requirement of Nash equilibria by a consistency-based bounded-rationality one. In this paper, the framework of empirical evidence is summarized, with an emphasis on perfect-monitoring repeated games. A less constraining notion of consistency is introduced. The fact that an xEEE in a perfect-monitoring repeated game induces a correlated equilibrium on the underlying one-shot game is proven. This result and the new notion of consistency are illustrated on the hawk-dove game. Finally, a method to build specific correlated equilibria from xEEEs is derived.

  7. Exogenous empirical-evidence equilibria in perfect-monitoring repeated games yield correlated equilibria

    KAUST Repository

    Dudebout, Nicolas

    2014-12-15

    This paper proves that exogenous empirical-evidence equilibria (xEEEs) in perfect-monitoring repeated games induce correlated equilibria of the associated one-shot game. An empirical-evidence equilibrium (EEE) is a solution concept for stochastic games. At equilibrium, agents\\' strategies are optimal with respect to models of their opponents. These models satisfy a consistency condition with respect to the actual behavior of the opponents. As such, EEEs replace the full-rationality requirement of Nash equilibria by a consistency-based bounded-rationality one. In this paper, the framework of empirical evidence is summarized, with an emphasis on perfect-monitoring repeated games. A less constraining notion of consistency is introduced. The fact that an xEEE in a perfect-monitoring repeated game induces a correlated equilibrium on the underlying one-shot game is proven. This result and the new notion of consistency are illustrated on the hawk-dove game. Finally, a method to build specific correlated equilibria from xEEEs is derived.

  8. Phase equilibria and P-T-X(Fe-Mg relations involving Gl-St-Cd-Als-Bi-Mu-Oz-Kfs-H2O in medium-high grade metapelites (KFASH, KMASH and KFMASH sistems

    Directory of Open Access Journals (Sweden)

    Martínez, F. J.

    1989-12-01

    Full Text Available In different areas of the Hercynian in the Iberian Peninsula some reactions are repeatedly observed in pelites, these reactions are: Staurolite + muscovite + quartz = Biotite+ Al2SiO5+ H2O Garnet + muscovite = Al2SiO5+ biotite+ quartzBiotite + Al2SiO5 + quartz = Cordierite + K feldspar+Hp In order to examinate the P-T stability fields of these, and other similar reactions, aH the univariant equilibria in multisystems with Gt-Cd-St-Bi-Mu-Als-Qz-HP, Gt-St-Bi-Mu-Fk-AIs-QzHp and Cd-St-Bi-Mu-Fk-AIs-Qz-H2O in Kp-FeO-AI2O r SiO2-H2O (KFASH system have been calculated, and their corresponding P-T grids have been constructed. The expansion of these reactions into divariant surfaces through the P-T-X (Fe-Mg space was made by studying the assemblage Gt-Cd-St-Bi-Mu-Fk-AIs-Qz-HP in K2O-FeO-MgO-Al2O3-SiO2-H2O (KFMASH with a Fe/Fe+Mg relationship Gt > St > Bi > Cd such as observed in most of natural pelites. A resultant grid was obtained by combining those obtained in the aboye systerns. This grid has been P-T located for PH20 = P19 near QFM buffer, and excess muscovite and quartz conditions Reaction slopes in this grid were calculated within different P-T surroundings from thermodynamic data as weH as by considering the existing experimental data. In addition to the stability fields of reactions the P-T-XFe-Mg theoric relations for three univariant and thirteen divariant reactions have been obtained. The grid confirms the imposibility of staurolite-K feldspar and Garnet-Cordierite-Muscovite coexistence, as weH as the extension of the stability fields for Garnet-Staurolite, Cordierite-Staurolite and Garnet-Cordierite assemblages in muscovite-poor metapelites.En rocas metapelíticas de diversas áreas en el Hercínico de la Península Ibérica se observan a menudo las siguientes reacciones: Estaurolita + moscovita + cuarzo = biotita + Al2SiO5+ H2OGranate + moscovita = Al2SiO5 + biotita ± cuarzo Biotita + Al2SiO5 + cuarzo = cordierita + feldespato pot

  9. Phase equilibria in the Mo-Fe-P system at 800 °C and structure of ternary phosphide (Mo(1-x)Fe(x))3P (0.10 ≤ x ≤ 0.15).

    Science.gov (United States)

    Oliynyk, Anton O; Lomnytska, Yaroslava F; Dzevenko, Mariya V; Stoyko, Stanislav S; Mar, Arthur

    2013-01-18

    Construction of the isothermal section in the metal-rich portion (ternary phases: (Mo(1-x)Fe(x))(2)P (x = 0.30-0.82) and (Mo(1-x)Fe(x))(3)P (x = 0.10-0.15). The occurrence of a Co(2)Si-type ternary phase (Mo(1-x)Fe(x))(2)P, which straddles the equiatomic composition MoFeP, is common to other ternary transition-metal phosphide systems. However, the ternary phase (Mo(1-x)Fe(x))(3)P is unusual because it is distinct from the binary phase Mo(3)P, notwithstanding their similar compositions and structures. The relationship has been clarified through single-crystal X-ray diffraction studies on Mo(3)P (α-V(3)S-type, space group I42m, a = 9.7925(11) Å, c = 4.8246(6) Å) and (Mo(0.85)Fe(0.15))(3)P (Ni(3)P-type, space group I4, a = 9.6982(8) Å, c = 4.7590(4) Å) at -100 °C. Representation in terms of nets containing fused triangles provides a pathway to transform these closely related structures through twisting. Band structure calculations support the adoption of these structure types and the site preference of Fe atoms. Electrical resistivity measurements on (Mo(0.85)Fe(0.15))(3)P reveal metallic behavior but no superconducting transition.

  10. Ballooning stable high beta tokamak equilibria

    International Nuclear Information System (INIS)

    Tuda, Takashi; Azumi, Masafumi; Kurita, Gen-ichi; Takizuka, Tomonori; Takeda, Tatsuoki

    1981-04-01

    The second stable regime of ballooning modes is numerically studied by using the two-dimensional tokamak transport code with the ballooning stability code. Using the simple FCT heating scheme, we find that the plasma can locally enter this second stable regime. And we obtained equilibria with fairly high beta (β -- 23%) stable against ballooning modes in a whole plasma region, by taking into account of finite thermal diffusion due to unstable ballooning modes. These results show that a tokamak fusion reactor can operate in a high beta state, which is economically favourable. (author)

  11. Critical beta for analytical spheromak equilibria

    International Nuclear Information System (INIS)

    Freire, E.M.; Clemente, R.A.

    1985-01-01

    The Mercier criterion is applied to two analytical spheromak equilibria, one with a spherical separatrix and the other with a cylindrical one of variable elongation. The maximum beta, defined as the ratio between the plasma pressure and the magnetic pressure averaged over the plasma volume, for which the criterion is satisfied on every magnetic surface, has been obtained. In the spherical model the critical beta is 0.003, while in the cylindrical case it is a function of the elongation of the separatrix with a maximum of 0.083. (author)

  12. Numerical determination of axisymmetric toroidal magnetohydrodynamic equilibria

    International Nuclear Information System (INIS)

    Johnson, J.L.; Dalhed, H.E.; Greene, J.M.

    1978-07-01

    Numerical schemes for the determination of stationary axisymmetric toroidal equilibria appropriate for modeling real experimental devices are given. Iterative schemes are used to solve the elliptic nonlinear partial differential equation for the poloidal flux function psi. The principal emphasis is on solving the free boundary (plasma-vacuum interface) equilibrium problem where external current-carrying toroidal coils support the plasma column, but fixed boundary (e.g., conducting shell) cases are also included. The toroidal current distribution is given by specifying the pressure and either the poloidal current or the safety factor profiles as functions of psi. Examples of the application of the codes to tokamak design at PPPL are given

  13. Guiding Center Equations in Toroidal Equilibria

    International Nuclear Information System (INIS)

    White, Roscoe; Zakharov, Leonid

    2002-01-01

    Guiding center equations for particle motion in a general toroidal magnetic equilibrium configuration are derived using magnetic coordinates. Previous derivations made use of Boozer coordinates, in which the poloidal and toroidal angle variables are chosen so that the Jacobian is inversely proportional to the square of the magnetic field. It is shown that the equations for guiding center motion in any equilibrium possessing nested flux surfaces have exactly the same simple form as those derived in this special case. This allows the use of more spatially uniform coordinates instead of the Boozer coordinates, greatly increasing the accuracy of calculations in large beta and strongly shaped equilibria

  14. A unifying approach to existence of Nash equilibria

    NARCIS (Netherlands)

    Balder, E.J.

    1997-01-01

    An approach initiated in [4] is shown to unify results about the existence of (i) Nash equilibria in games with at most countably many players, (ii) Cournot-Nash equilibrium distributions for large, anonymous games, and (iii) Nash equilibria (both mixed and pure) for continuum games. A new, central

  15. Understanding the effect of surface/bulk defects on the photocatalytic activity of TiO2: anatase versus rutile.

    Science.gov (United States)

    Yan, Junqing; Wu, Guangjun; Guan, Naijia; Li, Landong; Li, Zhuoxin; Cao, Xingzhong

    2013-07-14

    The sole effect of surface/bulk defects of TiO2 samples on their photocatalytic activity was investigated. Nano-sized anatase and rutile TiO2 were prepared by hydrothermal method and their surface/bulk defects were adjusted simply by calcination at different temperatures, i.e. 400-700 °C. High temperature calcinations induced the growth of crystalline sizes and a decrease in the surface areas, while the crystalline phase and the exposed facets were kept unchanged during calcination, as indicated by the characterization results from XRD, Raman, nitrogen adsorption-desorption, TEM and UV-Vis spectra. The existence of surface/bulk defects in calcined TiO2 samples was confirmed by photoluminescence and XPS spectra, and the surface/bulk defect ratio was quantitatively analyzed according to positron annihilation results. The photocatalytic activity of calcined TiO2 samples was evaluated in the photocatalytic reforming of methanol and the photocatalytic oxidation of α-phenethyl alcohol. Based on the characterization and catalytic results, a direct correlation between the surface specific photocatalytic activity and the surface/bulk defect density ratio could be drawn for both anatase TiO2 and rutile TiO2. The surface defects of TiO2, i.e. oxygen vacancy clusters, could promote the separation of electron-hole pairs under irradiation, and therefore, enhance the activity during photocatalytic reaction.

  16. Effect of solution composition on anatase to rutile transformation of sprayed TiO{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Juma, Albert Owino, E-mail: albert.juma@ttu.ee [Laboratory of Thin Film Chemical Technologies, Department of Materials Science, Tallinn University of Technology, Ehitajate tee 5, EE-19086 Tallinn (Estonia); Acik, Ilona Oja [Laboratory of Thin Film Chemical Technologies, Department of Materials Science, Tallinn University of Technology, Ehitajate tee 5, EE-19086 Tallinn (Estonia); Mikli, Valdek [Chair of Semiconductor Materials Technology, Department of Materials Science, Tallinn University of Technology, Ehitajate tee 5, EE-19086 Tallinn (Estonia); Mere, Arvo; Krunks, Malle [Laboratory of Thin Film Chemical Technologies, Department of Materials Science, Tallinn University of Technology, Ehitajate tee 5, EE-19086 Tallinn (Estonia)

    2015-11-02

    Acetylacetone is used as a chelating agent for titanium(IV) isopropoxide to inhibit hydrolysis and stabilize the precursor solution. The effect of the molar ratio between titanium(IV) isopropoxide and acetylacetone of 1:1, 1:2, 1:3 and 1:4 in the precursor solution on the morphological, structural and optical properties of TiO{sub 2} thin film was investigated. These properties were studied using Fourier transformed infrared spectroscopy, scanning electron microscopy, Raman spectroscopy, X-ray diffraction and UV–vis spectroscopy as a function of the molar ratios for the as-deposited thin films and films annealed at temperatures of 700, 800 and 950 °C. Mixed anatase and rutile phases were detected after annealing at 800 °C for 1:1 and 1:2 molar ratios and at 700 °C for 1:3 and 1:4 molar ratios. The optical band gap decreased from 3.45 to 3.02 eV with an increase in the annealing temperature in agreement with corresponding structural changes. - Highlights: • The grain sizes of TiO{sub 2} thin films could be varied over the range of 20 to 210 nm. • TTIP and AcacH ratio affects the transformation process from anatase to rutile. • TiO{sub 2} bandgap decreased from 3.45 to 3.02 eV with an increase in annealing temperature.

  17. First-principles atomistic Wulff constructions for an equilibrium rutile TiO2 shape modeling

    Science.gov (United States)

    Jiang, Fengzhou; Yang, Lei; Zhou, Dali; He, Gang; Zhou, Jiabei; Wang, Fanhou; Chen, Zhi-Gang

    2018-04-01

    Identifying the exposed surfaces of rutile TiO2 crystal is crucial for its industry application and surface engineering. In this study, the shape of the rutile TiO2 was constructed by applying equilibrium thermodynamics of TiO2 crystals via first-principles density functional theory (DFT) and Wulff principles. From the DFT calculations, the surface energies of six low-index stoichiometric facets of TiO2 are determined after the calibrations of crystal structure. And then, combined surface energy calculations and Wulff principles, a geometric model of equilibrium rutile TiO2 is built up, which is coherent with the typical morphology of fully-developed equilibrium TiO2 crystal. This study provides fundamental theoretical guidance for the surface analysis and surface modification of the rutile TiO2-based materials from experimental research to industry manufacturing.

  18. (Liquid + liquid) equilibria for (water + 1-propanol or acetone + β-citronellol) at different temperatures

    International Nuclear Information System (INIS)

    Li, Hengde; Han, Yongtao; Huang, Cheng; Yang, Chufen

    2015-01-01

    Graphical abstract: (Liquid + liquid) equilibrium data for systems composed of β-citronellol and aqueous 1-propanol or acetone are presented. Distribution ratios of 1-propanol and acetone in the mixtures are examined. The effect of the temperature on the ternary (liquid + liquid) equilibria is evaluated and discussed. - Highlights: • Ternary (liquid + liquid) equilibria containing β-citronellol are presented. • Distribution ratios of 1-propanol and acetone in the mixtures are examined. • The effect on the temperature of the systems is evaluated and discussed. - Abstract: On this paper, experimental (liquid + liquid) equilibrium (LLE) results are presented for systems composed of β-citronellol and aqueous 1-propanol or acetone. To evaluate the phase separation properties of β-citronellol in aqueous mixtures, LLE values for the ternary systems (water + 1-propanol + β-citronellol) and (water + acetone + β-citronellol) were determined with a tie-line method at T = (283.15, 298.15, and 313.15 ± 0.02) K and atmospheric pressure. The reliability of the experimental tie-lines was verified by the Hand and Bachman equations. Ternary phase diagrams, distribution ratios of 1-propanol and acetone in the mixtures are shown. The effect of the temperature on the ternary (liquid + liquid) equilibria was examined and discussed. The experimental LLE values were satisfactorily correlated by extended UNIQUAC and modified UNIQUAC models

  19. Measurement and modeling of high-pressure (vapour + liquid) equilibria of (CO2 + alcohol) binary systems

    International Nuclear Information System (INIS)

    Gutierrez, Jorge E.; Bejarano, Arturo; Fuente, Juan C. de la

    2010-01-01

    An apparatus based on a static-analytic method assembled in this work was utilized to perform high pressure (vapour + liquid) equilibria measurements with uncertainties estimated at 2 + 1-propanol), (CO 2 + 2-methyl-1-propanol), (CO 2 + 3-methyl-1-butanol), and (CO 2 + 1-pentanol) binary systems at temperatures of (313, 323, and 333) K, and at pressure range of (2 to 12) MPa. For all the (CO 2 + alcohol) systems, it was visually monitored to insure that there was no liquid immiscibility at the temperatures and pressures studied. The experimental results were correlated with the Peng-Robinson equation of state using the quadratic mixing rules of van der Waals with two adjustable parameters. The calculated (vapour + liquid) equilibria compositions were found to be in good agreement with the experimental values with deviations for the mol fractions <0.12 and <0.05 for the liquid and vapour phase, respectively.

  20. Equilibria of perceptrons for simple contingency problems.

    Science.gov (United States)

    Dawson, Michael R W; Dupuis, Brian

    2012-08-01

    The contingency between cues and outcomes is fundamentally important to theories of causal reasoning and to theories of associative learning. Researchers have computed the equilibria of Rescorla-Wagner models for a variety of contingency problems, and have used these equilibria to identify situations in which the Rescorla-Wagner model is consistent, or inconsistent, with normative models of contingency. Mathematical analyses that directly compare artificial neural networks to contingency theory have not been performed, because of the assumed equivalence between the Rescorla-Wagner learning rule and the delta rule training of artificial neural networks. However, recent results indicate that this equivalence is not as straightforward as typically assumed, suggesting a strong need for mathematical accounts of how networks deal with contingency problems. One such analysis is presented here, where it is proven that the structure of the equilibrium for a simple network trained on a basic contingency problem is quite different from the structure of the equilibrium for a Rescorla-Wagner model faced with the same problem. However, these structural differences lead to functionally equivalent behavior. The implications of this result for the relationships between associative learning, contingency theory, and connectionism are discussed.

  1. Adhesion between a rutile surface and a polyimide: a coarse grained molecular dynamics study

    Science.gov (United States)

    Kumar, Arun; Sudarkodi, V.; Parandekar, Priya V.; Sinha, Nishant K.; Prakash, Om; Nair, Nisanth N.; Basu, Sumit

    2018-04-01

    Titanium, due to its high strength to weight ratio and polyimides, due to their excellent thermal stability are being increasingly used in aerospace applications. We investigate the bonding between a (110) rutile substrate and a popular commercial polyimide, PMR-15, starting from the known atomic structure of the rutile substrate and the architecture of the polymer. First, the long PMR-15 molecule is divided into four fragments and an all-atom non-bonded forcefield governing the interaction between PMR-15 and a rutile substrate is developed. To this end, parameters of Buckingham potential for interaction between each atom in the fragments and the rutile surface are fitted, so as to ensure that the sum of non-bonded and electrostatic interaction energy between the substrate and a large number of configurations of each fragment, calculated by the quantum mechanical route and obtained from the fitted potential, is closely matched. Further, two coarse grained models of PMR-15 are developed—one for interaction between two coarse grained PMR-15 molecules and another for that between a coarse grained PMR-15 and the rutile substrate. Molecular dynamics simulations with the coarse grained models yields a traction separation law—a very useful tool for conducting continuum level finite element simulations of rutile-PMR-15 joints—governing the normal separation of a PMR-15 block from a flat rutile substrate. Moreover, detailed information about the affinity of various fragments to the substrate are also obtained. In fact, though the separation energy between rutile and PMR-15 turns out to be rather low, our analysis—with merely the molecular architecture of the polyimide as the starting point—provides a scheme for in-silico prediction of adhesion energies for new polyimide formulations.

  2. Modelling phase equilibria for acid gas mixtures using the CPA equation of state. Part VI. Multicomponent mixtures with glycols relevant to oil and gas and to liquid or supercritical CO2 transport applications

    DEFF Research Database (Denmark)

    Tsivintzelis, Ioannis; Kontogeorgis, Georgios M.

    2016-01-01

    to data on ternary and multicomponent mixtures) to model the phase behaviour of ternary and quaternary systems with CO2 and glycols. It is concluded that CPA performs satisfactorily for most multicomponent systems considered. Some differences between the various modelling approaches are observed....... This work is the last part of a series of studies, which aim to arrive in a single "engineering approach" for applying CPA to acid gas mixtures, without introducing significant changes to the model. An overall assessment, based also on the obtained results of this series (Tsivintzelis et al., 2010, 2011...

  3. Novel monoclinic zirconolite in Bi{sub 2}O{sub 3}–CuO–Ta{sub 2}O{sub 5} ternary system: Phase equilibria, structural and electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Tan, K.B., E-mail: tankb@science.upm.my [Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Chon, M.P. [Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Khaw, C.C. [Department of Mechanical and Material Engineering, Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, 53300 Setapak, Kuala Lumpur (Malaysia); Zainal, Z.; Taufiq Yap, Y.H.; Tan, P.Y. [Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia)

    2014-04-01

    Highlights: • Novel BCT monoclinic zirconolite phase was prepared through solid state reaction. • Comprehensive study of reaction mechanism was performed by careful firing control. • Qualitative structural and phase analyses were conducted. • Electrical response in broad range of temperature and frequency was investigated. - Abstract: Synthesis of novel monoclinic zirconolite, Bi{sub 1.92}Cu{sub 0.08}(Cu{sub 0.3}Ta{sub 0.7}){sub 2}O{sub 7.06} (β-BCT) using solid state reaction had been finalised at the firing temperature of 900 °C over 24 h. The X–ray diffraction pattern of β-BCT was fully indexed on a monoclinic symmetry, space group, C2/c with lattice constants, a = 13.1052 (8), b = 7.6749 (5), c = 12.162 (6), α = γ = 90° and β = 101.32° (1), respectively. The reaction mechanism study indicated phase formation was greatly influenced by the reaction between intermediate bismuth tantalate binary phases and CuO at elevated temperatures. β-BCT was thermally stable up to a temperature of 900 °C and contained spherulite grains with sizes ranging from 1 to 14 μm. Electrical properties of this material were characterised over a broad temperature range covering temperatures from 10 K to 874 K. At the temperature of 304 K, two semicircles were discernible in complex Cole–Cole plot showing an insulating grain boundary with C{sub gb} = 6.63 × 10{sup −9} F cm{sup −1} and a bulk response capacitance, C{sub b} = 6.74 × 10{sup −12} F cm{sup −1}. The Power law frequency-dependent ac conductivity of β-BCT was apparent in three frequency regimes; a low–frequency plateau regime, a high-frequency plateau regime and a dispersive regime taking place in the temperature range of 220–576 K. The frequency-dependent ac conductivity of β-BCT with increasing temperature was attributed to the thermal activated electrical conduction mechanism within the structure.

  4. Excited State Dynamics and Semiconductor-to-Metallic Phase Transition of VO2 Thin Film

    National Research Council Canada - National Science Library

    Liu, Huimin

    2004-01-01

    .... Vanadium dioxide shows an ultrafast, passive phase transition (PT) from a monoclinic semiconductor phase to a metallic tetragonal rutile structure when the sample temperature is above 68 degrees C...

  5. Phase equilibria in the NaF-CdO-NaPO{sub 3} system at 873 K and crystal structure and physico-chemical characterizations of the new Na{sub 2}CdPO{sub 4}F fluorophosphate

    Energy Technology Data Exchange (ETDEWEB)

    Aboussatar, Mohamed [Université Clermont Auvergne, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, UMR 6296 CNRS, BP 10448, F-63000 Clermont-Ferrand (France); Laboratoire de Physico-Chimie de l’État Solide, Faculté des Sciences de Sfax, Université de Sfax, BP 1171, 3000 Sfax (Tunisia); Mbarek, Aïcha [Laboratoire de Chimie Industrielle, Ecole Nationale d’Ingénieurs de Sfax, Université de Sfax, BP W3038, 3000 Sfax (Tunisia); Naili, Houcine [Laboratoire de Physico-Chimie de l’État Solide, Faculté des Sciences de Sfax, Université de Sfax, BP 1171, 3000 Sfax (Tunisia); El-Ghozzi, Malika [Université Clermont Auvergne, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, UMR 6296 CNRS, BP 10448, F-63000 Clermont-Ferrand (France); Chadeyron, Geneviève [Université Clermont Auvergne, Institut de Chimie de Clermont-Ferrand, UMR 6296 CNRS/UBP/SIGMA, BP 10448, F-63000 Clermont-Ferrand (France); Avignant, Daniel [Université Clermont Auvergne, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, UMR 6296 CNRS, BP 10448, F-63000 Clermont-Ferrand (France); Zambon, Daniel, E-mail: Daniel.Zambon@univ-bpclermont.fr [Université Clermont Auvergne, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, UMR 6296 CNRS, BP 10448, F-63000 Clermont-Ferrand (France)

    2017-04-15

    Isothermal sections of the diagram representing phase relationships in the NaF-CdO-NaPO{sub 3} system have been investigated by solid state reactions and powder X-ray diffraction. This phase diagram investigation confirms the polymorphism of the NaCdPO{sub 4} side component and the structure of the ß high temperature polymorph (orthorhombic, space group Pnma and unit cell parameters a=9.3118(2), b=7.0459(1), c=5.1849(1) Å has been refined. A new fluorophosphate, Na{sub 2}CdPO{sub 4}F, has been discovered and its crystal structure determined and refined from powder X-ray diffraction data. It exhibits a new 3D structure with orthorhombic symmetry, space group Pnma and unit cell parameters a=5.3731(1), b=6.8530(1), c=12.2691(2) Å. The structure is closely related to those of the high temperature polymorph of the nacaphite Na{sub 2}CaPO{sub 4}F and the fluorosilicate Ca{sub 2}NaSiO{sub 4}F but differs essentially in the cationic repartition since the structure is fully ordered with one Na site (8d) and one Cd site (4c). Relationships with other Na{sub 2}M{sup II}PO{sub 4}F (M{sup II}=Mg, Ca, Mn, Fe, Co, Ni) have been examined and the crystal-chemical and topographical analysis of these fluorophosphates is briefly reviewed. IR, Raman, optical and {sup 19}F, {sup 23}Na, {sup 31}P MAS NMR characterizations of Na{sub 2}CdPO{sub 4}F have been investigated. - Graphical abstract: The structure of the compound Na{sub 2}CdPO{sub 4}F, discovered during the study of the phase relationships in the NaF-CdO-NaPO{sub 3} system, has been determined and compared with other Na{sub 2}M{sup II}PO{sub 4}F fluorophosphates. - Highlights: • XRD analysis of the isothermal section of the NaF-CdO-NaPO{sub 3} system at 923 K. • Rietveld refinement of the high temperature polymorph β-NaCdPO{sub 4}. • Crystal structure of the new Na{sub 2}CdPO{sub 4}F fluorophosphate determined from powder XRD. • Crystal structure - composition relationships of Na{sub 2}M{sup II}PO{sub 4}F compounds

  6. Synthesis of high purity rutile nanoparticles from medium-grade Egyptian natural ilmenite

    Directory of Open Access Journals (Sweden)

    Mohamed G. Shahien

    2015-09-01

    Full Text Available The Egyptian magmatic ilmenite is classified as a medium-grade ore. The present work is an attempt to produce a high-quality TiO2 that can be used in several industries from this medium-grade raw material using the mechanical activation, carbothermic reduction, hydrochloric acid leaching and calcination. A mixture from the ilmenite (FeTiO3 and activated carbon was milled for 30 h. This mixture was annealed at 1200 °C for one hour and the product was leached by hydrochloric acid and calcined at 600 °C for two hours. The role of the ball milling was to grind the raw ilmenite to obtain the nano size, and the carbothermic reduction was to reduce all the Fe-Ti phases to a mixture from Fe metal and TiO2. Leaching procedure was carried out to remove all the Fe metal and obtain a high-grade TiO2. After leaching and calcination of the milled and annealed mixture of FeTiO3/C under the optimal conditions, TiO2 nanoparticles with a size of 10–100 nm and purity more than 95% were obtained. The qualifications of the synthesized high purity rutile nanoparticles from the Egyptian natural ilmenite match the conditions of many industrial applications.

  7. Optical studies of cobalt implanted rutile TiO2 (110) surfaces

    International Nuclear Information System (INIS)

    Joshi, Shalik Ram; Padmanabhan, B.; Chanda, Anupama; Mishra, Indrani; Malik, V.K.; Mishra, N.C.; Kanjilal, D.; Varma, Shikha

    2016-01-01

    Highlights: • The present study displays formation of nanostructures after Co implantation on TiO 2 surfaces. • Preferential sputtering leads to the creation of oxygen vacancies on the surface. • A large enhancement in visible light absorbance (nearly 5 times compared to pristine) is observed. • Creation of self-organized nanostructures and Ti 3+ oxygen vacancies promote photoabsorption. • Formation of Co-nanoclusters and Co–Ti–O phase play concerted role in enhancing photo-absorption. - Abstract: Present study investigates the photoabsorption properties of single crystal rutile TiO 2 (110) surfaces after they have been implanted with low fluences of cobalt ions. The surfaces, after implantation, demonstrate fabrication of nanostructures and anisotropic nano-ripple patterns. Creation of oxygen vacancies (Ti 3+ states), development of cobalt nano-clusters as well as band gap modifications have also been observed. Results presented here demonstrate that fabrication of self organized nanostructures, upon implantation, along with the development of oxygen vacancies and ligand field transitions of cobalt ion promote the enhancement of photo-absorbance in both UV (∼2 times) and visible (∼5 times) regimes. These investigations on nanostructured TiO 2 surfaces can be important for photo-catalysis.

  8. Ordered Fe(II)Ti(IV)O3 Mixed Monolayer Oxide on Rutile TiO2(011).

    Science.gov (United States)

    Halpegamage, Sandamali; Ding, Pan; Gong, Xue-Qing; Batzill, Matthias

    2015-08-25

    Oxide monolayers supported or intermixed with an oxide support are potential nanocatalysts whose properties are determined by the interplay with the support. For fundamental studies of monolayer oxides on metal oxide supports, well-defined systems are needed, but so far, the synthesis of monolayer oxides with long-range order on single-crystal oxide surfaces is rare. Here, we show by a combination of scanning tunneling microscopy, photoemission spectroscopy, and density functional theory (DFT)-based computational analysis that the rutile TiO2(011) surface supports the formation of an ordered mixed FeTiO3 monolayer. Deposition of iron in a slightly oxidizing atmosphere (10(-8) Torr O2) and annealing to 300 °C results in a well-ordered surface structure with Fe in a 2+ charge state and Ti in a 4+ charge states. Low-energy ion scattering suggests that the cation surface composition is close to half Fe and half Ti. This surface is stable in ultrahigh vacuum to annealing temperatures of 300 °C before the iron is reduced. DFT simulations confirm that a surface structure with coverage of 50% FeO units is stable and forms an ordered structure. Although distinct from known bulk phases of the iron-titanium oxide systems, the FeTiO3 monolayer exhibits some resemblance to the ilmenite structure, which may suggest that a variety of different mixed oxide phases (of systems that exist in a bulk ilmenite phase) may be synthesized in this way on the rutile TiO2(011) substrate.

  9. Modelling phase equilibria for acid gas mixtures using the CPA equation of state. Part VI. Multicomponent mixtures with glycols relevant to oil and gas and to liquid or supercritical CO_2 transport applications

    International Nuclear Information System (INIS)

    Tsivintzelis, Ioannis; Kontogeorgis, Georgios M.

    2016-01-01

    Highlights: • CPA EoS was applied to predict the phase behaviour of multicomponent mixtures containing CO_2, glycols, water and alkanes. • Mixtures relevant to oil and gas, CO_2 capture and liquid or supercritical CO_2 transport applications were investigated. • Results are presented using various modelling approaches/association schemes. • The predicting ability of the model was evaluated against experimental data. • Conclusions for the best modelling approach are drawn. - Abstract: In this work the Cubic Plus Association (CPA) equation of state is applied to multicomponent mixtures containing CO_2 with alkanes, water, and glycols. Various modelling approaches are used i.e. different association schemes for pure CO_2 (assuming that it is a non-associating compound, or that it is a self-associating fluid with two, three or four association sites) and different possibilities for modelling mixtures of CO_2 with other hydrogen bonding fluids (only use of one interaction parameter k_i_j or assuming cross association interactions and obtaining the relevant parameters either via a combining rule or using an experimental value for the cross association energy). Initially, new binary interaction parameters were estimated for (CO_2 + glycol) binary mixtures. Having the binary parameters from the binary systems, the model was applied in a predictive way (i.e. no parameters were adjusted to data on ternary and multicomponent mixtures) to model the phase behaviour of ternary and quaternary systems with CO_2 and glycols. It is concluded that CPA performs satisfactorily for most multicomponent systems considered. Some differences between the various modelling approaches are observed. This work is the last part of a series of studies, which aim to arrive in a single “engineering approach” for applying CPA to acid gas mixtures, without introducing significant changes to the model. An overall assessment, based also on the obtained results of this series (Tsivintzelis

  10. (Solid + liquid) isothermal evaporation phase equilibria in the aqueous ternary system (Li{sub 2}SO{sub 4} + MgSO{sub 4} + H{sub 2}O) at T = 308.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Wang Shiqiang [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008 (China); Graduate University of Chinese Academy of Sciences, Beijing 100039 (China); Deng Tianlong [Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008 (China); College of Materials, Chemistry and Chemical Engineering, Chengdu University Technology, Chengdu 610059 (China)], E-mail: dtl@cdut.edu.cn

    2008-06-15

    The solubility and the density in the aqueous ternary system (Li{sub 2}SO{sub 4} + MgSO{sub 4} + H{sub 2}O) at T = 308.15 K were determined by the isothermal evaporation. Our experimental results permitted the construction of the phase diagram and the plot of density against composition. It was found that there is one eutectic point for (Li{sub 2}SO{sub 4} . H{sub 2}O + MgSO{sub 4} . 7H{sub 2}O), two univariant curves, and two crystallization regions corresponding to lithium sulphate monohydrate (Li{sub 2}SO{sub 4} . H{sub 2}O) and epsomite (MgSO{sub 4} . 7H{sub 2}O). The system belongs to a simple co-saturated type, and neither double salts nor solid solution was found. Based on the Pitzer ion-interaction model and its extended HW models of aqueous electrolyte solution, the solubility of the ternary system at T = 308.15 K has been calculated. The predicted solubility agrees well with the experimental values.

  11. On Pure and (approximate) Strong Equilibria of Facility Location Games

    DEFF Research Database (Denmark)

    Hansen, Thomas Dueholm; Telelis, Orestis A.

    2008-01-01

    We study social cost losses in Facility Location games, where n selfish agents install facilities over a network and connect to them, so as to forward their local demand (expressed by a non-negative weight per agent). Agents using the same facility share fairly its installation cost, but every...... agent pays individually a (weighted) connection cost to the chosen location. We study the Price of Stability (PoS) of pure Nash equilibria and the Price of Anarchy of strong equilibria (SPoA), that generalize pure equilibria by being resilient to coalitional deviations. For unweighted agents on metric...

  12. Measurement and modeling of high-pressure (vapor + liquid) equilibria of (CO2 + alkanol) binary systems

    International Nuclear Information System (INIS)

    Bejarano, Arturo; Gutierrez, Jorge E.; Araus, Karina A.; Fuente, Juan C. de la

    2011-01-01

    Research highlights: → (Vapor + liquid) equilibria of three (CO 2 + C 5 alcohol) binary systems were measured. → Complementary data are reported at (313, 323 and 333) K and from (2 to 11) MPa. → No liquid immiscibility was observed at the temperatures and pressures studied. → Experimental data were correlated with the PR-EoS and the van de Waals mixing rules. → Correlation results showed relative deviations ≤8 % (liquid) and ≤2 % (vapor). - Abstract: Complementary isothermal (vapor + liquid) equilibria data are reported for the (CO 2 + 3-methyl-2-butanol), (CO 2 + 2-pentanol), and (CO 2 + 3-pentanol) binary systems at temperatures of (313, 323, and 333) K, and at pressure range of (2 to 11) MPa. For all (CO 2 + alcohol) systems, it was visually monitored that there was no liquid immiscibility at the temperatures and pressures studied. The experimental data were correlated with the Peng-Robinson equation of state using the quadratic mixing rules of van der Waals with two adjustable parameters. The calculated (vapor + liquid) equilibria compositions were found to be in good agreement with the experimental data with deviations for the mole fractions <8% and <2% for the liquid and vapor phase, respectively.

  13. Effect of temperature on acid-base equilibria in separation techniques. A review.

    Science.gov (United States)

    Gagliardi, Leonardo G; Tascon, Marcos; Castells, Cecilia B

    2015-08-19

    Studies on the theoretical principles of acid-base equilibria are reviewed and the influence of temperature on secondary chemical equilibria within the context of separation techniques, in water and also in aqueous-organic solvent mixtures, is discussed. In order to define the relationships between the retention in liquid chromatography or the migration velocity in capillary electrophoresis and temperature, the main properties of acid-base equilibria have to be taken into account for both, the analytes and the conjugate pairs chosen to control the solution pH. The focus of this review is based on liquid-liquid extraction (LLE), liquid chromatography (LC) and capillary electrophoresis (CE), with emphasis on the use of temperature as a useful variable to modify selectivity on a predictable basis. Simplified models were evaluated to achieve practical optimizations involving pH and temperature (in LLE and CE) as well as solvent composition in reversed-phase LC. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. FP-LAPW Calculations of the EFG at Cd Impurities in Rutile SnO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Errico, L. A.; Fabricius, G.; Renteria, M. [Universidad Nacional de La Plata, Instituto de Fisica La Plata (IFLP-CONICET) - Departamento de Fisica, Facultad de Ciencias Exactas (Argentina)

    2001-11-15

    We report an ab initio study of the electric-field gradient (EFG) at Cd impurities located at the cation site in the semiconductor SnO{sub 2}(rutile phase). The study was performed with the WIEN97 implementation of the FP-LAPW method. In order to simulate the diluted Cd-impurity in the SnO{sub 2} host and to calculate the electronic structure of the system we used a 72-atoms super-cell, studying the relaxation introduced by the impurity in the lattice. The free-relaxation process performed shows that the relaxations of the oxygen nearest-neighbors of the impurity are not isotropic. Our prediction for the EFG tensor are compared with experimental results and point-charge model predictions.

  15. Rutile TiO{sub 2} active-channel thin-film transistor using rapid thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sung-Jin; Heo, Kwan-Jun; Yoo, Su-Chang; Choi, Seong-Gon [Chungbuk National University, Cheongju (Korea, Republic of); Chang, Seung-Wook [Samsung Display, Co., Ltd., Suwon (Korea, Republic of)

    2014-10-15

    TiO{sub 2} active-channel thin-film transistors (TFTs), in which the bottom-gate top-contact architecture was prepared with atomic layer deposition grown TiO{sub 2} as the semiconducting layer, were fabricated and then investigated based on key process parameters, such as the rapid thermal annealing (RTA) temperature. Structural analyses suggested that TiO{sub 2} films annealed at temperatures above 500 .deg. C changed from an amorphous to a rutile phase. The TFT with a TiO{sub 2} semiconductor annealed at 600 .deg. C exhibited strongly-saturated output characteristics, a much higher on/off current ratio of 4.3 x 10{sup 5}, and an electron mobility of 0.014 cm{sup 2}/Vs. Moreover, the potential for manipulating TiO{sub 2}-based TFTs with RTA methodology was demonstrated through the realization of a simple resistive-load inverter.

  16. Direct view at colossal permittivity in donor-acceptor (Nb, In) co-doped rutile TiO2

    International Nuclear Information System (INIS)

    Mandal, Suman; Pal, Somnath; Hazarika, Abhijit; Kundu, Asish K.; Menon, Krishnakumar S. R.; Rioult, Maxime; Belkhou, Rachid

    2016-01-01

    Topical observations of colossal permittivity (CP) with low dielectric loss in donor-acceptor cations co-doped rutile TiO 2 have opened up several possibilities in microelectronics and energy-storage devices. Yet, the precise origin of the CP behavior, knowledge of which is essential to empower the device integration suitably, is highly disputed in the literature. From spectromicroscopic approach besides dielectric measurements, we explore that microscopic electronic inhomogeneities along with the nano-scale phase boundaries and the low temperature polaronic relaxation are mostly responsible for such a dielectric behavior, rather than electron-pinned defect-dipoles/grain-boundary effects as usually proposed. Donor-acceptor co-doping results in a controlled carrier-hopping inevitably influencing the dielectric loss while invariably upholding the CP value.

  17. Direct view at colossal permittivity in donor-acceptor (Nb, In) co-doped rutile TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, Suman, E-mail: suman.mandal@sscu.iisc.ernet.in; Pal, Somnath; Hazarika, Abhijit [Solid State and Structural Chemistry Unit, Indian Institute of Science, Bengaluru 560012 (India); Kundu, Asish K.; Menon, Krishnakumar S. R. [Surface Physics and Material Science Division, Saha Institute of Nuclear Physics, Kolkata 700064 (India); Rioult, Maxime; Belkhou, Rachid [Synchrotron SOLEIL, L' Orme des Merisiers Saint-Aubin, 91192 Gif-sur-Yvette (France)

    2016-08-29

    Topical observations of colossal permittivity (CP) with low dielectric loss in donor-acceptor cations co-doped rutile TiO{sub 2} have opened up several possibilities in microelectronics and energy-storage devices. Yet, the precise origin of the CP behavior, knowledge of which is essential to empower the device integration suitably, is highly disputed in the literature. From spectromicroscopic approach besides dielectric measurements, we explore that microscopic electronic inhomogeneities along with the nano-scale phase boundaries and the low temperature polaronic relaxation are mostly responsible for such a dielectric behavior, rather than electron-pinned defect-dipoles/grain-boundary effects as usually proposed. Donor-acceptor co-doping results in a controlled carrier-hopping inevitably influencing the dielectric loss while invariably upholding the CP value.

  18. Epitaxial single-crystal thin films of MnxTi1-xO2-δ grown on (rutile)TiO2 substrates with pulsed laser deposition: Experiment and theory

    Energy Technology Data Exchange (ETDEWEB)

    Ilton, Eugene S.; Droubay, Timothy C.; Chaka, Anne M.; Kovarik, Libor; Varga, Tamas; Arey, Bruce W.; Kerisit, Sebastien N.

    2015-02-01

    Epitaxial rutile-structured single-crystal MnxTi1-xO2-δ films were synthesized on rutile- (110) and -(001) substrates using pulsed laser deposition. The films were characterized by reflection high-energy electron diffraction (RHEED), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and aberration-corrected transmission electron microscopy (ACTEM). Under the present conditions, 400oC and PO2 = 20 mTorr, single crystal epitaxial thin films were grown for x = 0.13, where x is the nominal average mole fraction of Mn. In fact, arbitrarily thick films could be grown with near invariant Mn/Ti concentration profiles from the substrate/film interface to the film surface. In contrast, at x = 0.25, Mn became enriched towards the surface and a secondary nano-scale phase formed which appeared to maintain the basic rutile structure but with enhanced z-contrast in the tunnels, or tetrahedral interstitial sites. Ab initio thermodynamic calculations provided quantitative estimates for the destabilizing effect of expanding the β-MnO2 lattice parameters to those of TiO2-rutile, the stabilizing effect of diluting Mn with increasing Ti concentration, and competing reaction pathways.

  19. First principles calculation of L21+A2 coherent equilibria in the Fe-Al-Ti system

    International Nuclear Information System (INIS)

    Alonso, Paula R.; Gargano, Pablo H.; Ramirez-Caballero, Gustavo E.; Balbuena, Perla B.; Rubiolo, Gerardo H.

    2009-01-01

    By combining first-principles density functional total energy calculations and statistical mechanics the ground state and the phase equilibria at finite temperatures of the ternary system Fe-Al-Ti have been investigated. Total energy calculations have been performed by means of the Wien 2k code to establish the ground state energetic. A cluster expansion method was therewith used to describe solid solutions. At several chosen finite temperatures the cluster variation method in the irregular tetrahedron approximation was employed in order to calculate the iron rich ternary bcc equilibria. It is confirmed that there are two kinds of phase separations of the bcc phase, A2+L2 1 and B2+L2 1 .

  20. Re-analysis of exponential rigid-rotor astron equilibria

    International Nuclear Information System (INIS)

    Lovelace, R.V.; Larrabee, D.A.; Fleischmann, H.H.

    1978-01-01

    Previous studies of exponential rigid-rotor astron equilibria include particles which are not trapped in the self-field of the configuration. The modification of these studies required to exclude untrapped particles is derived

  1. Influence of morphology and surface characteristics on the photocatalytic activity of rutile titania nanocrystals

    International Nuclear Information System (INIS)

    Nag, Manaswita; Guin, Debanjan; Basak, Pratyay; Manorama, Sunkara V.

    2008-01-01

    This article presents the synthesis of phase-pure rutile titania with different morphologies via hydrothermal method at significantly low temperatures (40-150 deg. C) without any additives and their application as efficient photocatalyst for environmental remediation. Phase and morphology has been determined with X-ray diffraction (XRD) and transmission electron microscopy (TEM). Ultra violet diffuse reflectance spectroscopy (UV-DRS) shows the optical band-gap in the range of ∼2.8-3.1 eV and Brunauer-Emmett-Teller specific surface area is found to be between 70 and 140 m 2 /g depending on the synthesis conditions. Raman spectroscopic analyses of the samples provide valuable insights into the structural and stoichiometric details. Photodegradation of the pollutant azo-dye, methyl orange (MO) in presence and absence of oxygen was performed to study the photocatalytic efficiency of the synthesized materials. Complete photodegradation of the dye is confirmed with high performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS) study. Dependence of dye photodegradation rate on morphology, specific surface area, surface nonstoichiometry and acidity were investigated in detail. Catalyst performance was compared from the rate constants obtained for each reaction using non-linear least square fitting (NLSF) to the experimental data in a concentration ratio (C 0 /C t ) versus time (t) plot which shows extraordinarily high activity for all samples compared to commercial reference. Among them the catalyst synthesized at 40 deg. C for 16 h showed best activity. Kinetic study of the reaction matches well with simulated fit to experimental data and confirms to be pseudo-first order reaction

  2. Surface current equilibria from a geometric point of view

    International Nuclear Information System (INIS)

    Kaiser, R.; Salat, A.

    1993-04-01

    This paper addresses the inverse problem of the existence of surface current MHD equilibria in toroidal geometry with vanishing magnetic field inside. Inverse means that the plasma-vacuum interface rather than the external wall or conductors are given and the latter remain to be determined. This makes a reformulation of the problem possible in geometric terms: What toroidal surfaces with analytic parameterization allow a simple analytic covering by geodesics? If such a covering by geodesics (field lines) exists, their orthogonal trajectories (current lines) also form a simple covering and are described by a function satisfying a nonlinear partial differential equation of the Hamilton-Jacobi type whose coefficients are combinations of the metric elements of the surface. All known equilibria - equilibria with zero and infinite rotational transform and the symmetric ones in the case of finite rotational transform - turn out to be solutions of separable cases of that equation and allow a unified description if the toroidal surface is parametrized in the moving trihedral associated with a closed curve. Analogously to volume current equilibria, the only continuous symmetries compatible with separability are plane, helical and axial symmetry. In the nonseparable case numerical evidence is presented for cases with chaotic behaviour of geodesics, thus restricting possible equilibria for these surfaces. For weak deviation from axisymmetry KAM-type behaviour is observed, i.e. destruction of geodesic coverings with a low rational rotational transform and preservation of those with irrational rotational transform. A previous attempt to establish three-dimensional surface current equilibria on the basis of the KAM theorem is rejected as incomplete, and a complete proof of the existence of equilibria in the weakly nonaxisymmetric case, based on the twist theorem for mappings, is given. Finally, for a certain class of strong deviations from axisymmetry an analytic criterion is

  3. Computation of Stackelberg Equilibria of Finite Sequential Games

    DEFF Research Database (Denmark)

    Bosanski, Branislav; Branzei, Simina; Hansen, Kristoffer Arnsfelt

    2015-01-01

    The Stackelberg equilibrium is a solution concept that describes optimal strategies to commit to: Player~1 (the leader) first commits to a strategy that is publicly announced, then Player~2 (the follower) plays a best response to the leader's choice. We study Stackelberg equilibria in finite...... sequential (i.e., extensive-form) games and provide new exact algorithms, approximate algorithms, and hardness results for finding equilibria for several classes of such two-player games....

  4. Field line diversion properties of finite β-helias equilibria

    International Nuclear Information System (INIS)

    Hayashi, Takaya; Schwenn, Ulrich; Strumberger, Erika.

    1992-01-01

    The diversion properties of the magnetic field outside the last closed magnetic surface of a Helias stellarator configuration are investigated for finite pressure equilibria. The results indicate that a divertor concept which has been developed from the diversion properties of the corresponding vacuum field can be maintained for finite pressure equilibria. Cross-field particle transport is simulated by a simplified scrape-off layer (SOL) model. (author)

  5. On the uniqueness of fully informative rational expectations equilibria

    OpenAIRE

    Peter DeMarzo; Costis Skiadas

    1998-01-01

    This paper analyzes two equivalent equilibrium notions under asymmetric information: risk neutral rational expectations equilibria (rn-REE), and common knowledge equilibria. We show that the set of fully informative rn-REE is a singleton, and we provide necessary and sufficient conditions for the existence of partially informative rn-REE. In a companion paper (DeMarzo and Skiadas (1996)) we show that equilibrium prices for the larger class of quasi-complete economies can be characterized as r...

  6. Determination of 3D Equilibria from Flux Surface Knowledge Only

    International Nuclear Information System (INIS)

    Mynick, H.E.; Pomphrey, N.

    2001-01-01

    We show that the method of Christiansen and Taylor, from which complete tokamak equilibria can be determined given only knowledge of the shape of the flux surfaces, can be extended to 3-dimensional equilibria, such as those of stellarators. As for the tokamak case, the given geometric knowledge has a high degree of redundancy, so that the full equilibrium can be obtained using only a small portion of that information

  7. The Activation Mechanism of Bi3+ Ions to Rutile Flotation in a Strong Acidic Environment

    Directory of Open Access Journals (Sweden)

    Wei Xiao

    2017-07-01

    Full Text Available Lead hydroxyl compounds are known as rutile flotation of the traditional activated component, but the optimum pH range for flotation is 2–3 using styryl phosphoric acid (SPA as collector, without lead hydroxyl compounds in slurry solution. In this study, Bi3+ ions as a novel activator was investigated. The results revealed that the presence of Bi3+ ions increased the surface potential, due to the specific adsorption of hydroxyl compounds, which greatly increases the adsorption capacity of SPA on the rutile surface. Bi3+ ions increased the activation sites through the form of hydroxyl species adsorbing on the rutile surface and occupying the steric position of the original Ca2+ ions. The proton substitution reaction occurred between the hydroxyl species of Bi3+ ions (Bi(OHn+(3−n and the hydroxylated rutile surface, producing the compounds of Ti-O-Bi2+. The micro-flotation tests results suggested that Bi3+ ions could improve the flotation recovery of rutile from 61% to 90%, and from 61% to 64% for Pb2+ ions.

  8. Facile synthesis of hierarchical nanostructured rutile titania for lithium-ion battery

    International Nuclear Information System (INIS)

    Fei Hailong; Wei Mingdeng

    2011-01-01

    Highlights: → Rutile TiO 2 sub-microflowers and sub-microspheres with different building blocks as anode materials of lithium-ion battery. → Controllable morphologies with oxalic acid by the hydrothermal technique. → Sub-microflower and sub-microspheres constructed by well organized nanorods exhibited high capacity and good cycle stability. → Small size building blocks nanorods enhance the transfer rate of Li-ion. - Abstract: A facile hydrothermal method is developed to prepare rutile titania sub-microflowers consisting of nanorods with oxalic acid and TiOSO 4 as reagents. The diameter of sub-microflowers and nanorods is found to be ca. 800 and 40 nm, respectively. Also, the shape and size of building blocks in rutile titania sub-microflowers can be considerably controlled via adjusting the reaction time and reactant amounts. Rutile titania sub-microflowers composed of nanorods display higher discharge capacity and better rate cycle stability than other rutile titania nanostructures as lithium-ion battery anode material due to enhancing the Li-ion transfer rate for small size building blocks.

  9. Reduction of Islands in Full-pressure Stellarator Equilibria

    International Nuclear Information System (INIS)

    Hudson, S.R.; Monticello, D.A.; Reiman, A.H.

    2001-01-01

    The control of magnetic islands is a crucial issue in designing Stellarators. Islands are associated with resonant radial magnetic fields at rational rotational-transform surfaces and can lead to chaos and poor plasma confinement. In this article, we show that variations in the resonant fields of a full-pressure stellarator equilibrium can be related to variations in the boundary via a coupling matrix, and inversion of this matrix determines a boundary modification for which the island content is significantly reduced. The numerical procedure is described and the results of island optimization are presented. Equilibria with islands are computed using the Princeton Iterative Equilibrium Solver, and resonant radial fields are calculated via construction of quadratic-flux-minimizing surfaces. A design candidate for the National Compact Stellarator Experiment [Phys. Plasmas 8, 2001], which has a large island, is used to illustrate the technique. Small variations in the boundary shape are used to reduce island size and to reverse the phase of a major island chain

  10. Detrital rutile geochemistry and thermometry from the Dabie orogen: Implications for source-sediment links in a UHPM terrane

    Science.gov (United States)

    Liu, Lei; Xiao, Yilin; Wörner, G.; Kronz, A.; Simon, K.; Hou, Zhenhui

    2014-08-01

    This study explores the potential of detrital rutile geochemistry and thermometry as a provenance tracer in rocks from the Central Dabie ultrahigh-pressure metamorphic (UHPM) zone in east-central China that formed during Triassic continental collision. Trace element data of 176 detrital rutile grains selected from local river sediments and 91 rutile grains from distinct bedrocks in the Shuanghe and Bixiling areas, obtained by both electron microprobe (EMP) and in situ LA-ICP-MS analyses, suggest that geochemical compositions and thermometry of detrital rutiles are comparable to those from their potential source rocks. After certification of the Cr-Nb discrimination method for the Central Dabie UHPM zone, we show that 29% of the detrital rutiles in the Shuanghe area were derived from metamafic sources whereas in the Bixiling area that it is up to 76%. Furthermore, the proportion of distinct types of detrital rutiles combined with modal abundances of rutile in metapelites and metamafic bedrocks can be used to estimate the proportion of different source lithologies. Based on this method the proportion of mafic source rocks was estimated to ∼10% at Shuanghe and >60% at Bixiling, respectively, which is consistent with the proportions of eclogite (the major rutile-bearing metamafic rock) distribution in the field. Therefore, the investigation of detrital rutiles is a potential way to evaluate the proportion of metamafic rocks and even to prospect for metamafic bodies in UHPM terranes. Zr-in-rutile temperatures were calculated at different pressures and compared with temperatures derived from rock-in rutiles and garnet-clinopyroxene Fe-Mg thermometers. Temperatures calculated for detrital rutiles range from 606 °C to 707 °C and 566 °C to 752 °C in Shuanghe and Bixiling, respectively, at P = 3 GPa with an average temperatures of ca. 630 °C for both areas. These temperature averages and ranges are similar to those calculated for rutiles from surrounding source rocks

  11. Two-dimensional magnetohydrodynamic equilibria with flow and studies of equilibria fluctuations

    International Nuclear Information System (INIS)

    Agim, Y.Z.

    1989-08-01

    A set of reduced ideal MHD equations is derived to investigate equilibria of plasmas with mass flow in general two-dimensional geometry. These equations provide a means of investigating the effects of flow on self-consistent equilibria in a number of new two-dimensional configurations such as helically symmetric configurations with helical axis, which are relevant to stellarators, as well as axisymmetric configurations. It is found that as in the axisymmetric case, general two-dimensional flow equilibria are governed by a second-order quasi-linear partial differential equation for a magnetic flux function, which is coupled to a Bernoulli-type equation for the density. The equation for the magnetic flux function becomes hyperbolic at certain critical flow speeds which follow from its characteristic equation. When the equation is hyperbolic, shock phenomena may exist. As a particular example, unidirectional flow along the lines of symmetry is considered. In this case, the equation mentioned above is always elliptic. An exact solution for the case of helically symmetric unidirectional flow is found and studied to determine flow effects on the magnetic topology. In second part of this thesis, magnetic fluctuations due to the thermally excited MHD waves are investigated using fluid and kinetic models to describe stable, uniform, compressible plasma in the range above the drift wave frequency and below the ion cyclotron frequency. It is shown that the fluid model with resistivity yields spectral densities which are roughly Lorentzian, exhibit equipartition with no apparent cutoff in wavenumber space and a Bohm-type diffusion coefficient. Under certain conditions, the ensuing transport may be comparable to classical values. For a phenomenological cutoff imposed on the spectrum, the typical fluctuating-to-equilibrium magnetic field ratio is found to be of the order of 10 -10

  12. Controlled formation of anatase and rutile TiO2 thin films by reactive magnetron sputtering

    Directory of Open Access Journals (Sweden)

    Damon Rafieian

    2015-09-01

    Full Text Available We discuss the formation of TiO2 thin films via DC reactive magnetron sputtering. The oxygen concentration during sputtering proved to be a crucial parameter with respect to the final film structure and properties. The initial deposition provided amorphous films that crystallise upon annealing to anatase or rutile, depending on the initial sputtering conditions. Substoichiometric films (TiOx<2, obtained by sputtering at relatively low oxygen concentration, formed rutile upon annealing in air, whereas stoichiometric films formed anatase. This route therefore presents a formation route for rutile films via lower (<500 °C temperature pathways. The dynamics of the annealing process were followed by in situ ellipsometry, showing the optical properties transformation. The final crystal structures were identified by XRD. The anatase film obtained by this deposition method displayed high carriers mobility as measured by time-resolved microwave conductance. This also confirms the high photocatalytic activity of the anatase films.

  13. Thermodynamic Equilibria and Extrema Analysis of Attainability Regions and Partial Equilibria

    CERN Document Server

    Gorban, Alexander N; Kaganovich, Boris M; Keiko, Alexandre V; Shamansky, Vitaly A; Shirkalin, Igor A

    2006-01-01

    This book discusses mathematical models that are based on the concepts of classical equilibrium thermodynamics. They are intended for the analysis of possible results of diverse natural and production processes. Unlike the traditional models, these allow one to view the achievable set of partial equilibria with regards to constraints on kinetics, energy and mass exchange and to determine states of the studied systems of interest for the researcher. Application of the suggested models in chemical technology, energy and ecology is illustrated in the examples.

  14. Modeling of phase equilibria with CPA using the homomorph approach

    DEFF Research Database (Denmark)

    Breil, Martin Peter; Tsivintzelis, Ioannis; Kontogeorgis, Georgios

    2011-01-01

    For association models, like CPA and SAFT, a classical approach is often used for estimating pure-compound and mixture parameters. According to this approach, the pure-compound parameters are estimated from vapor pressure and liquid density data. Then, the binary interaction parameters, kij, are ...

  15. MOLECULAR SIMULATION OF PHASE EQUILIBRIA FOR COMPLEX FLUIDS

    Energy Technology Data Exchange (ETDEWEB)

    Athanassios Z. Panagiotopoulos

    2009-09-09

    The general area of this project was the development and application of novel molecular simulation methods for prediction of thermodynamic and structural properties of complex polymeric, surfactant and ionic fluids. Over this project period, we have made considerable progress in developing novel algorithms to meet the computational challenges presented by the strong or long-range interactions in these systems and have generated data for well-defined mod-els that can be used to test theories and compare to experimental data. Overall, 42 archival papers and many invited and contributed presentations and lectures have been based on work supported by this project. 6 PhD, 1 M.S. and 2 postdoctoral students have been associated with this work, as listed in the body of the report.

  16. A Metamodel for Crustal Magmatism: Phase Equilibria of Giant Ignimbrites

    OpenAIRE

    Fowler, Sarah J.; Spera, Frank J.

    2017-01-01

    Diverse explanations exist for the large-volume catastrophic eruptions that formed the Bishop Tuff of Long Valley in eastern California, the Bandelier Tuff in New Mexico, and the tuffs of Yellowstone, Montana, USA. These eruptions are among the largest on Earth within the last 2 Myr. A common factor in recently proposed petrogenetic scenarios for each system is multistage processing, in which a crystal mush forms by crystal fractionation and is then remobilized to liberate high-silica liquids...

  17. Phase equilibria analysis in chromium-nickel steel

    International Nuclear Information System (INIS)

    Gurevich, Yu.G.; Frage, N.R.; Dudorova, T.A.

    1982-01-01

    Comparison of calculation results of nitrogen solubility in liquid multicomponent iron alloys containing essential concentrations of alloying transition metals is conducted. Nitrogen solubility has been calculated by the interaction parameters of the first order, by the interaction parameters of the first and second orders by the Schurmann-Kunze method; by the formula [% N]=[% N]sub(Fe)(Asub(Fe)/Asub(m)(1-1/6 μsub(j=3)sup(m)epsilonsub(N)sup(j)xsub(j))sup(6), where Asub(Fe) - mass of iron mol; Asub(m) - mass of alloy mol; xsub(j) - mol ratio of j-element; epsilonsub(N)sup(j) - Wagner parameter of interaction for nitrogen in iron base alloys. The calculation data have been compared with the experimental values of nitrogen solubility in iron alloys at 1600 deg C. Advantages of calculation by the formula in respect to other calculation methods of nitrogen solubility in iron base alloys are clarified. Approximately pointed out is the region of compositions for which accountancy of interaction parameters of the second and third orders is necessary

  18. Molecular Simulation Of Phase Equilibria For Complex Fluids

    International Nuclear Information System (INIS)

    Panagiotopoulos, Athanassios Z.

    2009-01-01

    The general area of this project was the development and application of novel molecular simulation methods for prediction of thermodynamic and structural properties of complex polymeric, surfactant and ionic fluids. Over this project period, we have made considerable progress in developing novel algorithms to meet the computational challenges presented by the strong or long-range interactions in these systems and have generated data for well-defined mod-els that can be used to test theories and compare to experimental data. Overall, 42 archival papers and many invited and contributed presentations and lectures have been based on work supported by this project. 6 PhD, 1 M.S. and 2 postdoctoral students have been associated with this work, as listed in the body of the report.

  19. Thermophysical Properties and Phase Equilibria of Materials Systems

    National Research Council Canada - National Science Library

    Reeber, R

    2002-01-01

    .... In those regions experiments are difficult and data is often marginally reliable. In a series of papers, we have developed models for predicting these properties for a wide range of metals, ceramics and semiconductors...

  20. Phase equilibria in alloys of nickel with molybdenum and carbon

    International Nuclear Information System (INIS)

    Barash, O.M.; Gorskaya, R.V.; Legkaya, T.N.; Oshkaderov, S.P.

    1990-01-01

    Experimental methods in combination with thermodynamic calculation have been used to construct a portion of fusibility curve of the ternary Ni-Mo-C system, to determine concentration dependences of the temperature range and the temperature of the termination of eutectic transformation zh↔γ+Mo 2 C. Coordinates of the temperature peak of this eutectic transformation are determined

  1. The CHEASE code for toroidal MHD equilibria

    Energy Technology Data Exchange (ETDEWEB)

    Luetjens, H. [Ecole Polytechnique, 91 - Palaiseau (France). Centre de Physique Theorique; Bondeson, A. [Chalmers Univ. of Technology, Goeteborg (Sweden). Inst. for Electromagnetic Field Theory and Plasma Physics; Sauter, O. [ITER-San Diego, La Jolla, CA (United States)

    1996-03-01

    CHEASE solves the Grad-Shafranov equation for the MHD equilibrium of a Tokamak-like plasma with pressure and current profiles specified by analytic forms or sets of data points. Equilibria marginally stable to ballooning modes or with a prescribed fraction of bootstrap current can be computed. The code provides a mapping to magnetic flux coordinates, suitable for MHD stability calculations or global wave propagation studies. The code computes equilibrium quantities for the stability codes ERATO, MARS, PEST, NOVA-W and XTOR and for the global wave propagation codes LION and PENN. The two-dimensional MHD equilibrium (Grad-Shafranov) equation is solved in variational form. The discretization uses bicubic Hermite finite elements with continuous first order derivates for the poloidal flux function {Psi}. The nonlinearity of the problem is handled by Picard iteration. The mapping to flux coordinates is carried out with a method which conserves the accuracy of the cubic finite elements. The code uses routines from the CRAY libsci.a program library. However, all these routines are included in the CHEASE package itself. If CHEASE computes equilibrium quantities for MARS with fast Fourier transforms, the NAG library is required. CHEASE is written in standard FORTRAN-77, except for the use of the input facility NAMELIST. CHEASE uses variable names with up to 8 characters, and therefore violates the ANSI standard. CHEASE transfers plot quantities through an external disk file to a plot program named PCHEASE using the UNIRAS or the NCAR plot package. (author) figs., tabs., 34 refs.

  2. Unifying dynamical and structural stability of equilibria

    Science.gov (United States)

    Arnoldi, Jean-François; Haegeman, Bart

    2016-09-01

    We exhibit a fundamental relationship between measures of dynamical and structural stability of linear dynamical systems-e.g. linearized models in the vicinity of equilibria. We show that dynamical stability, quantified via the response to external perturbations (i.e. perturbation of dynamical variables), coincides with the minimal internal perturbation (i.e. perturbations of interactions between variables) able to render the system unstable. First, by reformulating a result of control theory, we explain that harmonic external perturbations reflect the spectral sensitivity of the Jacobian matrix at the equilibrium, with respect to constant changes of its coefficients. However, for this equivalence to hold, imaginary changes of the Jacobian's coefficients have to be allowed. The connection with dynamical stability is thus lost for real dynamical systems. We show that this issue can be avoided, thus recovering the fundamental link between dynamical and structural stability, by considering stochastic noise as external and internal perturbations. More precisely, we demonstrate that a linear system's response to white-noise perturbations directly reflects the intensity of internal white-noise disturbance that it can accommodate before becoming stochastically unstable.

  3. The CHEASE code for toroidal MHD equilibria

    International Nuclear Information System (INIS)

    Luetjens, H.

    1996-03-01

    CHEASE solves the Grad-Shafranov equation for the MHD equilibrium of a Tokamak-like plasma with pressure and current profiles specified by analytic forms or sets of data points. Equilibria marginally stable to ballooning modes or with a prescribed fraction of bootstrap current can be computed. The code provides a mapping to magnetic flux coordinates, suitable for MHD stability calculations or global wave propagation studies. The code computes equilibrium quantities for the stability codes ERATO, MARS, PEST, NOVA-W and XTOR and for the global wave propagation codes LION and PENN. The two-dimensional MHD equilibrium (Grad-Shafranov) equation is solved in variational form. The discretization uses bicubic Hermite finite elements with continuous first order derivates for the poloidal flux function Ψ. The nonlinearity of the problem is handled by Picard iteration. The mapping to flux coordinates is carried out with a method which conserves the accuracy of the cubic finite elements. The code uses routines from the CRAY libsci.a program library. However, all these routines are included in the CHEASE package itself. If CHEASE computes equilibrium quantities for MARS with fast Fourier transforms, the NAG library is required. CHEASE is written in standard FORTRAN-77, except for the use of the input facility NAMELIST. CHEASE uses variable names with up to 8 characters, and therefore violates the ANSI standard. CHEASE transfers plot quantities through an external disk file to a plot program named PCHEASE using the UNIRAS or the NCAR plot package. (author) figs., tabs., 34 refs

  4. Axisymmetric plasma equilibria in a Kerr metric

    Science.gov (United States)

    Elsässer, Klaus

    2001-10-01

    Plasma equilibria near a rotating black hole are considered within the multifluid description. An isothermal two-component plasma with electrons and positrons or ions is determined by four structure functions and the boundary conditions. These structure functions are the Bernoulli function and the toroidal canonical momentum per mass for each species. The quasi-neutrality assumption (no charge density, no toroidal current) allows to solve Maxwell's equations analytically for any axisymmetric stationary metric, and to reduce the fluid equations to one single scalar equation for the stream function \\chi of the positrons or ions, respectively. The basic smallness parameter is the ratio of the skin depth of electrons to the scale length of the metric and fluid quantities, and, in the case of an electron-ion plasma, the mass ratio m_e/m_i. The \\chi-equation can be solved by standard methods, and simple solutions for a Kerr geometry are available; they show characteristic flow patterns, depending on the structure functions and the boundary conditions.

  5. Axisymmetric Plasma Equilibria in General Relativity

    Science.gov (United States)

    Elsässer, Klaus

    Axisymmetric plasma equilibria near a rotating black hole are considered within the multifluid description. An isothermal two-component plasma with electrons and positrons or ions is determined by four structure functions and the boundary conditions. These structure functions are the Bernoulli function and the toroidal canonical momentum per mass for each species; they remain arbitrary if no gain and loss processes are considered, in close analogy to the free flux functions in ideal magnetohydrodynamics. Several simplifying assumptions allow the reduction of the basic equations to one single scalar equation for the stream function χ of positrons or ions, respectively, playing the rôle of the Grad/Shafranov equation in magnetohydrodynamics; in particular, Maxwell's equations can be solved analytically for a quasineutral plasma when both the charge density and the toroidal electric current density are negligible (in contrast to the Tokamak situation). The basic smallness parameter is the ratio of the skin depth of electrons to the scale length of the metric and fluid quantities, and, in the case of an electron-ion plasma, the mass ratio me/mi. The χ-equation can be solved by standard methods, and simple solutions for a Kerr geometry are available; they show characteristic flow patterns, depending on the structure functions and the boundary conditions.

  6. An Inelastic Neutron Scattering Study of Confined Surface Water on Rutile Nanoparticles

    International Nuclear Information System (INIS)

    Spencer, Elinor; Levchenko, Andrey; Ross, Nancy; Kolesnikov, Alexander I.; Boerio-Goates, Juliana; Woodfield, Brian; Navrotsky, Alexandra; Li, Guangshe

    2009-01-01

    The vibrational density of states (VDOS) for water confined on the surface of rutile-TiO2 nanoparticles has been extracted from low temperature inelastic neutron scattering spectra. Two rutile-TiO2 nanoparticle samples that differ in their respective levels of hydration, namely TiO2 0.37H2O (1) and TiO2 0.22H2O (2) have been studied. The temperature dependency of the heat capacities for the two samples has been quantified from the VDOS. The results from this study are compared with previously reported data for water confined on anatase-TiO2 nanoparticles.

  7. Isotope effects in ion-exchange equilibria in aqueous and mixed solvent systems

    International Nuclear Information System (INIS)

    Gupta, A.R.

    1979-01-01

    Isotope effects in ion-exchange equilibria in aqueous and mixed solvents are analyzed in terms of the general features of ion-exchange equilibria and of isotope effects in chemical equilibria. The special role of solvent fractionation effects in ion-exchange equilibria in mixed solvents is pointed out. The various situations arising in isotope fractionation in ion exchange in mixed solvents due to solvent fractionation effects are theoretically discussed. The experimental data on lithium isotope effects in ion-exchange equilibria in mixed solvents are shown to conform to the above situations. The limitations of ion-exchange equilibria in mixed solvents for isotope fractionation are pointed out. 3 tables

  8. Phase relations in the system NaCl-KCl-H2O: IV. Differential thermal analysis of the sylvite liquidus in the KCl-H2O binary, the liquidus in the NaCl-KCl-H2O ternary, and the solidus in the NaCl-KCl binary to 2 kb pressure, and a summary of experimental data for thermodynamic-PTX analysis of solid-liquid equilibria at elevated P-T conditions

    Science.gov (United States)

    Chou, I.-Ming; Sterner, S.M.; Pitzer, Kenneth S.

    1992-01-01

    The sylvite liquidus in the binary system KCl-H2O and the liquidus in the ternary system NaCl-KCl-H2O were determined by using isobaric differential thermal analysis (DTA) cooling scans at pressures up to 2 kbars. Sylvite solubilities along the three-phase curve in the binary system KCl-H2O were obtained by the intersection of sylvite-liquidus isopleths with the three-phase curve in a P-T plot. These solubility data can be represented by the equation Wt.% KCl (??0.2) = 12.19 + 0.1557T - 5.4071 ?? 10-5 T2, where 400 ??? T ??? 770??C. These data are consistent with previous experimental observations. The solidus in the binary system NaCl-KCl was determined by using isobaric DTA heating scans at pressures up to 2 kbars. Using these liquidus and solidus data and other published information, a thermodynamic-PTX analysis of solid-liquid equilibria at high pressures and temperatures for the ternary system has been performed and is presented in an accompanying paper (Part V of this series). However, all experimental liquidus, solidus, and solvus data used in this analysis are summarized in this report (Part IV) and they are compared with the calculated values based on the analysis. ?? 1992.

  9. Rutile TiO2 nanorod arrays directly grown on Ti foil substrates towards lithium-ion micro-batteries

    International Nuclear Information System (INIS)

    Dong Shanmu; Wang Haibo; Gu Lin; Zhou Xinhong; Liu Zhihong; Han Pengxian; Wang Ya; Chen Xiao; Cui Guanglei; Chen Liquan

    2011-01-01

    Nanosized rutile TiO 2 is one of the most promising candidates for anode material in lithium-ion micro-batteries owing to their smaller dimension in ab-plane resulting in an enhanced performance for area capacity. However, few reports have yet emerged up to date of rutile TiO 2 nanorod arrays growing along c-axis for Li-ion battery electrode application. In this study, single-crystalline rutile TiO 2 nanorod arrays growing directly on Ti foil substrates have been fabricated using a template-free method. These nanorods can significantly improve the electrochemical performance of rutile TiO 2 in Li-ion batteries. The capacity increase is about 10 times in comparison with rutile TiO 2 compact layer.

  10. Absolute band structure determination on naturally occurring rutile with complex chemistry: Implications for mineral photocatalysis on both Earth and Mars

    Science.gov (United States)

    Li, Yan; Xu, Xiaoming; Li, Yanzhang; Ding, Cong; Wu, Jing; Lu, Anhuai; Ding, Hongrui; Qin, Shan; Wang, Changqiu

    2018-05-01

    Rutile is the most common and stable form of TiO2 that ubiquitously existing on Earth and other terrestrial planets like Mars. Semiconducting mineral such as rutile-based photoredox reactions have been considered to play important roles in geological times. However, due to the inherent complexity in chemistry, the precision determination on band structure of natural rutile and the theoretical explanation on its solar-driven photochemistry have been hardly seen yet. Considering the multiple minor and trace elements in natural rutile, we firstly obtained the single-crystal crystallography, mineralogical composition and defects characteristic of the rutile sample by using both powder and single crystal X-ray diffraction, electron microprobe analysis and X-ray photoelectron spectroscopy. Then, the band gap was accurately determined by synchrotron-based O K-edge X-ray absorption and emission spectra, which was firstly applied to natural rutile due to its robustness on compositions and defects. The absolute band edges of the rutile sample was calculated by considering the electronegativity of the atoms, band gap and point of zero charge. Besides, after detecting the defect energy levels by photoluminescence spectra, we drew the schematic band structure of natural rutile. The band gap (2.7 eV) of natural rutile was narrower than that of synthetic rutile (3.0 eV), and the conduction and valence band edges of natural rutile at pH = pHPZC were determined to be -0.04 V and 2.66 V (vs. NHE), respectively. The defect energy levels located at nearly the middle position of the forbidden band. Further, we used theoretical calculations to verify the isomorphous substitution of Fe and V for Ti gave rise to the distortion of TiO6 octahedron and created vacancy defects in natural rutile. Based on density functional theory, the narrowed band gap was interpreted to the contribution of Fe-3d and V-3d orbits, and the defect energy state was formed by hybridization of O-2p and Fe/V/Ti-3d

  11. Bonding of gold nanoclusters to oxygen vacancies on rutile TiO2(110)

    DEFF Research Database (Denmark)

    Lopez, Nuria; schaub, R.; Thostrup, P.

    2003-01-01

    Through an interplay between scanning tunneling microscopy (STM) and density functional theory (DFT) calculations, we show that bridging oxygen vacancies are the active nucleation sites for Au clusters on the rutile TiO2(110) surface. We find that a direct correlation exists between a decrease in...

  12. Defect annealing in Mn/Fe-implanted TiO2(rutile)

    CERN Document Server

    Gunnlaugsson, H P; Masenda, H; Mølholt, T E; Johnston, K; Bharuth-Ram, K; Gislason, H; Langouche, G; Naidoo, D; Ólafsson, S; Svane, A; Weyer, G

    2014-01-01

    A study of the annealing processes and charge state of dilute Fe in rutile TiO2 single crystals was performed in the temperature range 143-662 K, utilizing online 57Fe emission Mossbauer spectroscopy following low concentrations ( 350 K.

  13. Construction of hydrophobic wood surfaces by room temperature deposition of rutile (TiO2) nanostructures

    Science.gov (United States)

    Rongbo Zheng; Mandla A. Tshabalala; Qingyu Li; Hongyan Wang

    2015-01-01

    A convenient room temperature approach was developed for growing rutile TiO2 hierarchical structures on the wood surface by direct hydrolysis and crystallization of TiCl3 in saturated NaCl aqueous solution.The morphology and the crystal structure of TiO2 coated on the wood surface were characterized...

  14. Ion Adsorption at the Rutile-Water Interface: Linking Molecular and Macroscopic Properties

    Czech Academy of Sciences Publication Activity Database

    Zhang, Z.; Fenter, P.; Cheng, L.; Sturchio, N. C.; Bedzyk, M. J.; Předota, Milan; Bandura, A.; Kubicki, J. D.; Lvov, S. N.; Cummings, P. T.; Chialvo, A. A.; Ridley, M. K.

    2004-01-01

    Roč. 20, č. 12 (2004), s. 4954-4969 ISSN 0743-7463 R&D Projects: GA ČR GP203/03/P083 Institutional research plan: CEZ:AV0Z4072921 Keywords : ion adsorption rutile Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.295, year: 2004

  15. Ion adsorption on oxides : surface charge formation and cadmium binding on rutile and hematite

    NARCIS (Netherlands)

    Fokkink, L.G.J.

    1987-01-01

    The adsorption of charge-determining (H +and OH -) and cadmium ions on rutile (TiO 2 ) and hematite (α-Fe

  16. A novel chemical scheme for flotation of rutile from eclogite tailing

    Directory of Open Access Journals (Sweden)

    Bo Xu

    Full Text Available A novel chemical scheme for the flotation of rutile from eclogite tailings has been developed in this work. It consists of lead ion as the activator, sodium fluorosilicate (SF as the depressant, and styryl phosphonic acid (SPA and n-octyl alcohol (OCT as the collector. By using the proposed scheme to treat a feed ore of 4.5% TiO2, a rougher concentrate of grade 84.47% TiO2 was achieved with the recovery of 61.5%. Also, the scheme made a high flotation rate for rutile. The scheme was applied to closed-circuit flotation (one-stage rougher flotation, two-stage scavenger flotation and two-stage cleaner flotation, produced a concentrate of 92% TiO2 with the recovery of 70%. It is shown that the new chemical scheme would be a potential one for the effective separation of rutile from eclogite ores. Keywords: Rutile, Flotation, Reagents, Eclogite tailings

  17. Controlled formation of anatase and rutile TiO2 thin films by reactive magnetron sputtering

    OpenAIRE

    Rafieian Boroujeni, Damon; Ogieglo, Wojciech; Savenije, Tom; Lammertink, Rob G.H.

    2015-01-01

    We discuss the formation of TiO2 thin films via DC reactive magnetron sputtering. The oxygen concentration during sputtering proved to be a crucial parameter with respect to the final film structure and properties. The initial deposition provided amorphous films that crystallise upon annealing to anatase or rutile, depending on the initial sputtering conditions. Substoichiometric films (TiOx

  18. Effective dose in the manufacturing process of rutile covered welding electrodes.

    Science.gov (United States)

    Herranz, M; Rozas, S; Pérez, C; Idoeta, R; Núñez-Lagos, R; Legarda, F

    2013-03-01

    Shielded metal arc welding using covered electrodes is the most common welding process. Sometimes the covering contains naturally occurring radioactive materials (NORMs). In Spain the most used electrodes are those covered with rutile mixed with other materials. Rutile contains some detectable natural radionuclides, so it can be considered a NORM. This paper mainly focuses on the use of MCNP (Monte Carlo N-Particle Transport Code) as a predictive tool to obtain doses in a factory which produces this type of electrode and assess the radiological impact in a specific facility after estimating the internal dose.To do this, in the facility, areas of highest radiation and positions of workers were identified, radioactive content of rutile and rutile covered electrodes was measured, and, considering a worst possible scenario, external dose at working points has been calculated using MCNP. This procedure has been validated comparing the results obtained with those from a pressurised ionisation chamber and TLD dosimeters. The internal dose has been calculated using DCAL (dose and risk calculation). The doses range between 8.8 and 394 μSv yr(-1), always lower than the effective dose limit for the public, 1 mSv yr(-1). The highest dose corresponds to the mixing area.

  19. Volcano Relations for Oxidation of Hydrogen Halides over Rutile Oxide Surfaces

    DEFF Research Database (Denmark)

    Toftelund, Anja; Man, Isabela C.; Hansen, Heine A.

    2012-01-01

    over a range of different rutile oxide surfaces. Based on the scaling relations, two descriptors are identified that describe the reactions uniquely. By combining scaling with the micro-kinetic model, activity volcanoes for the three different oxidation reactions are derived. It is found...

  20. Exsolution in niobian rutile from the pegmatite deposit at greenbushes, Australia

    Czech Academy of Sciences Publication Activity Database

    Klementová, Mariana; Rieder, M.

    2004-01-01

    Roč. 42, č. 6 (2004), s. 1859-1870 ISSN 0008-4476 R&D Projects: GA ČR(CZ) GA205/01/1126 Keywords : rutile * ferrocolumbite * ixiolite Subject RIV: CA - Inorganic Chemistry Impact factor: 1.207, year: 2004

  1. Picosecond charge transport in rutile at high carrier densities studiedby transient terahertz spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Zajac, Vít; Němec, Hynek; Kužel, Petr

    2016-01-01

    Roč. 94, č. 11 (2016), 1-9, č. článku 115206. ISSN 1098-0121 R&D Projects: GA ČR GA13-12386S Institutional support: RVO:68378271 Keywords : terahertz spectroscopy * charge transport * TiO 2 * rutile * ultrafast spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.736, year: 2014

  2. Preparation and spectroscopic characterization of visible light sensitized N doped TiO2 (rutile)

    International Nuclear Information System (INIS)

    Livraghi, S.; Czoska, A.M.; Paganini, M.C.; Giamello, E.

    2009-01-01

    Nitrogen doped TiO 2 represents one of the most promising material for photocatalitic degradation of environmental pollutants with visible light. However, at present, a great deal of activity is devoted to the anatase polymorph while few data about rutile are available. In the present paper we report an experimental characterization of N doped polycrystalline rutile TiO 2 prepared via sol-gel synthesis. Nitrogen doping does not affect the valence band to conduction band separation but, generates intra band gap localized states which are responsible of the on set of visible light absorption. The intra band gap states correspond to a nitrogen containing defect similar but not coincident with that recently reported for N doped anatase. - Graphical abstract: Nitrogen doped TiO 2 represents one of the most promising material for photocatalitic degradation of environmental pollutants with visible light. However, at present, a great deal of activity is devoted to the anatase polymorph while few data about rutile are available. In the present paper we report an experimental characterization of N doped polycrystalline rutile TiO 2 prepared via sol-gel synthesis

  3. Mathematical Model for Multicomponent Adsorption Equilibria Using Only Pure Component Data

    DEFF Research Database (Denmark)

    Marcussen, Lis

    2000-01-01

    A mathematical model for nonideal adsorption equilibria in multicomponent mixtures is developed. It is applied with good results for pure substances and for prediction of strongly nonideal multicomponent equilibria using only pure component data. The model accounts for adsorbent...

  4. Kinetics, Thermodynamics and Isotherm studies on Adsorption of Eriochrome Black-T from aqueous solution using Rutile TiO2

    Science.gov (United States)

    Priyadarshini, B.; Rath, P. P.; Behera, S. S.; Panda, S. R.; Sahoo, T. R.; Parhi, P. K.

    2018-02-01

    In this study, rutile phase of TiO2 particles have been synthesized by co-precipitation method and is used as an adsorbent for removal of toxic azo dye Eriochrome black-T (EBT) from aqueous solution. The rutile phase of TiO2 was confirmed by the X-ray powder diffraction pattern. Effect of initial dye concentration, adsorbent dose, pH, agitation speed and temperature on the adsorption process of EBT was examined. Removal of EBT was increased by increasing in adsorbent dose and decrease in initial dye concentration and pH. The optimum conditions resulted were: 25 ppm initial dye concentration, 20 mg adsorbent dose and pH of 2. Using Langmuir, Freundlich and Temkin isotherm models, equilibrium data was determined. The Freundlich model showed the best fit for uptake of the EBT dye, which evident that the process of adsorption of EBT dye onto TiO2 particles was heterogeneous. The kinetic data were analyzed using pseudo-first order, pseudo-second order and intraparticle diffusion equation. The pseudo-second order showed the best fit for the kinetic studies (R2 = 0.999), which ascertains that the adsorption process was of chemisorptions type. The intraparticle diffusion model indicated a linear relationship (R2= 0.99) suggesting the pore diffusion to be a limiting step in the overall adsorption process.

  5. Structural dependence of threshold displacement energies in rutile, anatase and brookite TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, M., E-mail: marc.robinson@curtin.edu.au [Nanochemistry Research Institute, Curtin University, GPO Box U1987, Perth, WA 6845 (Australia); Marks, N.A. [Discipline of Physics and Astronomy, Curtin University, Perth, WA 6845 (Australia); Lumpkin, G.R. [Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia)

    2014-09-15

    Systematic molecular dynamics simulations of low energy cascades have been performed to examine how threshold displacement events are effected by changes in crystal structure. Exploiting the structural proximity of the rutile, anatase and brookite polymorphs of TiO{sub 2}, a quantitative examination of defect production has been carried out including detailed defect analysis and the determination of values of the threshold displacement energy (E{sub d}). Across all polymorphs comparable values of E{sub d} are reported for oxygen at around 20 eV, with the value for Ti in rutile (73 ± 2 eV) significantly higher than that in brookite (34 ± 1 eV) and anatase (39 ± 1 eV). Quantifying defect formation probability as a function of Primary Knock-on Atom (PKA) energy, simulations in rutile indicate a consistent reduction in defect formation at energies higher than E{sub d} relative to anatase and brookite. Defect cluster analysis reveals a significant proportion of di-Frenkel pairs in anatase at Ti PKA energies around E{sub d}. These clusters, which are stabilised by the localisation of two Frenkel pairs, are associated with a recombination barrier of approximately 0.19 eV. As such, annihilation is likely under typical experimental conditions which suggests an expected increase in the measured Ti value of E{sub d}. Identical O defect populations produced at the threshold by the O PKA in both rutile and anatase explain the comparable values of E{sub d}. At higher O PKA energies, the commencement of defect production on both sublattices in anatase is observed in contrast to the confinement of defects to the O sublattice in rutile. The overall trends reported are consistent with in-situ irradiation experiments and thermal spike simulations, suggesting the contrasting radiation response of the polymorphs of TiO{sub 2} is apparent during the initial stages of defect production. - Highlights: • Systematic calculation of threshold displacement energies (E{sub d

  6. Ballooning mode second stability region for sequences of tokamak equilibria

    International Nuclear Information System (INIS)

    Sugiyama, L.; Mark, J.W.K.

    A numerical study of several sequences of tokamak equilibria derived from two flux conserving sequences confirms the tendency of high n ideal MHD ballooning modes to stabilize for values of the plasma beta greater than a second critical beta, for sufficiently favorable equilibria. The major stabilizing effect of increasing the inverse rotational transform profile q(Psi) for equilibria with the same flux surface geometry is shown. The unstable region shifts toward larger shear d ln q/d ln γ and the width of the region measured in terms of the poloidal beta or a pressure gradient parameter, for fixed shear, decreases. The smaller aspect ratio sequences are more sensitive to changes in q and have less stringent limits on the attainable value of the plasma beta in the high beta stable region. Finally, the disconnected mode approximation is shown to provide a reasonable description of the second high beta stability boundary

  7. Nematic Equilibria on a Two-Dimensional Annulus

    KAUST Repository

    Lewis, A. H.; Aarts, D. G. A. L.; Howell, P. D.; Majumdar, A.

    2017-01-01

    We study planar nematic equilibria on a two-dimensional annulus with strong and weak tangent anchoring, in the Oseen–Frank theoretical framework. We analyze a radially invariant defect-free state and compute analytic stability criteria for this state in terms of the elastic anisotropy, annular aspect ratio, and anchoring strength. In the strong anchoring case, we define and characterize a new spiral-like equilibrium which emerges as the defect-free state loses stability. In the weak anchoring case, we compute stability diagrams that quantify the response of the defect-free state to radial and azimuthal perturbations. We study sector equilibria on sectors of an annulus, including the effects of weak anchoring and elastic anisotropy, giving novel insights into the correlation between preferred numbers of boundary defects and the geometry. We numerically demonstrate that these sector configurations can approximate experimentally observed equilibria with boundary defects.

  8. Numerical computation of FCT equilibria by inverse equilibrium method

    International Nuclear Information System (INIS)

    Tokuda, Shinji; Tsunematsu, Toshihide; Takeda, Tatsuoki

    1986-11-01

    FCT (Flux Conserving Tokamak) equilibria were obtained numerically by the inverse equilibrium method. The high-beta tokamak ordering was used to get the explicit boundary conditions for FCT equilibria. The partial differential equation was reduced to the simultaneous quasi-linear ordinary differential equations by using the moment method. The regularity conditions for solutions at the singular point of the equations can be expressed correctly by this reduction and the problem to be solved becomes a tractable boundary value problem on the quasi-linear ordinary differential equations. This boundary value problem was solved by the method of quasi-linearization, one of the shooting methods. Test calculations show that this method provides high-beta tokamak equilibria with sufficiently high accuracy for MHD stability analysis. (author)

  9. Nematic Equilibria on a Two-Dimensional Annulus

    KAUST Repository

    Lewis, A. H.

    2017-01-16

    We study planar nematic equilibria on a two-dimensional annulus with strong and weak tangent anchoring, in the Oseen–Frank theoretical framework. We analyze a radially invariant defect-free state and compute analytic stability criteria for this state in terms of the elastic anisotropy, annular aspect ratio, and anchoring strength. In the strong anchoring case, we define and characterize a new spiral-like equilibrium which emerges as the defect-free state loses stability. In the weak anchoring case, we compute stability diagrams that quantify the response of the defect-free state to radial and azimuthal perturbations. We study sector equilibria on sectors of an annulus, including the effects of weak anchoring and elastic anisotropy, giving novel insights into the correlation between preferred numbers of boundary defects and the geometry. We numerically demonstrate that these sector configurations can approximate experimentally observed equilibria with boundary defects.

  10. Numerical calculation of axisymmetric non-neutral plasma equilibria

    International Nuclear Information System (INIS)

    Spencer, R.L.; Rasband, S.N.; Vanfleet, R.R.

    1993-01-01

    Efficient techniques for computing axisymmetric non-neutral plasma equilibria are described. These equilibria may be obtained either by requiring global thermal equilibrium, by specifying the midplane radial density profile, or by specifying the radial profile of ∫n dz. Both splines and finite-differences are used, and the accuracy of the two is compared by using a new characterization of the thermal equilibrium density profile which gives a simple formula for estimating the radial and axial gradient scale lengths of thermal equilibria. It is found that for global thermal equilibrium 1% accuracy is achieved with splines if the distance between neighboring splines is about two Debye lengths while finite differences require a grid spacing of about one-half Debye length to achieve the same accuracy

  11. Longitudinal traveling waves bifurcating from Vlasov plasma equilibria

    International Nuclear Information System (INIS)

    Holloway, J.P.

    1989-01-01

    The kinetic equations governing longitudinal motion along a straight magnetic field in a multi-species collisionless plasma are investigated. A necessary condition for the existence of small amplitude spatially periodic equilibria and traveling waves near a given spatially uniform background equilibrium is derived, and the wavelengths which such solutions must approach as their amplitude decreases to zero are discussed. A sufficient condition for the existence of these small amplitude waves is also established. This is accomplished by studying the nonlinear ODE for the potential which arises when the distribution functions are represented in a BGK form; the arbitrary functions of energy that describe the BGK representation are tested as an infinite dimensional set of parameters in a bifurcation theory for the ODE. The positivity and zero current condition in the wave frame of the BGK distribution functions are maintained. The undamped small amplitude nonlinear waves so constructed can be made to satisfy the Vlasov dispersion relation exactly, but in general they need only satisfy it approximately. Numerical calculations reveal that even a thermal equilibrium electron-proton plasma with equal ion and electron temperatures will support undamped traveling waves with phase speeds greater than 1.3 times the electron velocity; the dispersion relation for this case exhibits both Langmuir and ion-acoustic branches as long wavelength limits, and shows how these branches are in fact connected by short wavelength waves of intermediate frequency. In apparent contradiction to the linear theory of Landau, these exact solutions of the kinetic equations do not damp; this contradiction is explained by observing that the linear theory is, in general, fundamentally incapable of describing undamped traveling waves

  12. The Importance of Water-Hydrocarbon Phase Equilibria During Reservoir Production and Drilling Operations Nouveaux défis liés à la présence d'équilibres eau-hydrocarbures lors des opérations de production et de forage

    Directory of Open Access Journals (Sweden)

    Zhou H.

    2006-12-01

    Full Text Available The inevitable presence of water in high pressure-high temperature reservoirs leads to a number of new challenges for petroleum engineers. A brief state of the art on water-hydrocarbon phase equilibria is presented. It appears that large amounts of water may be present in the hydrocarbon phase (up to 10% molar, and non negligible amounts of gas can dissolve in water. Based on experimental data, a large number of models have been developed. However, concerning the limitations of the data, caution is expressed about the correctness of some models. Recent studies have proven the usefulness of Henry's constants to predict hydrocarbon solubilities in water. The new challenges that are raised by this problem are discussed based on a number of recent publications. The water present in the hydrocarbon may lead to salt deposits downwell, and it must be taken into account in order to estimate the amount of gas in place. It can also result in modifications of the saturation pressure. Due to the presence of water, additional treatment is needed for pipe transport. On the other hand, the large amount of hydrocarbons dissolved in the water phase may result in a modification of the hydrocarbon composition, especially when reservoir pressure becomes very low. The increased toxicity of the water, containing either H2S or aromatics, can become a real burden for gas reservoirs in contact with aquifers or when disposing of production water. During drilling, large amounts of dissolved gas can become very hazardous, increasing the risk of eruption. A particular attention must be paid to acid gas injection in reservoirs, as the true effect of the injected gas may not be straightforward to predict. In conclusion, in light of the industrial importance of this information, some general guidelines are provided concerning additional data to be gathered and ideas for improving current models. La présence inévitable d'eau dans les réservoirs à hautes pression et temp

  13. Ideal MHD beta-limits of poloidally asymmetric equilibria

    Energy Technology Data Exchange (ETDEWEB)

    Todd, A.M.M.; Miller, A.E.; Grimm, R.C.; Okabayashi, M.; Dalhed, H.E. Jr.

    1981-05-01

    The ideal MHD stability of poloidally asymmetric equilibria, which are typical of a tokamak reactor design with a single-null poloidal divertor is examined. As with symmetric equilibria, stability to non-axisymmetric modes improves with increasing triangularity and ellipticity, and with lower edge safety factor. Pressure profiles optimized with respect to ballooning stability are obtained for an asymmetric shape, resulting in ..beta../sub critical/ approx. = 5.7%. The corresponding value for an equivalent symmetric shape is ..beta../sub critical/ approx. = 6.5%.

  14. Ideal MHD beta-limits of poloidally asymmetric equilibria

    International Nuclear Information System (INIS)

    Todd, A.M.M.; Miller, A.E.; Grimm, R.C.; Okabayashi, M.; Dalhed, H.E. Jr.

    1981-05-01

    The ideal MHD stability of poloidally asymmetric equilibria, which are typical of a tokamak reactor design with a single-null poloidal divertor is examined. As with symmetric equilibria, stability to non-axisymmetric modes improves with increasing triangularity and ellipticity, and with lower edge safety factor. Pressure profiles optimized with respect to ballooning stability are obtained for an asymmetric shape, resulting in β/sub critical/ approx. = 5.7%. The corresponding value for an equivalent symmetric shape is β/sub critical/ approx. = 6.5%

  15. Nash Equilibria in Symmetric Graph Games with Partial Observation

    DEFF Research Database (Denmark)

    Bouyer, Patricia; Markey, Nicolas; Vester, Steen

    2017-01-01

    We investigate a model for representing large multiplayer games, which satisfy strong symmetry properties. This model is made of multiple copies of an arena; each player plays in his own arena, and can partially observe what the other players do. Therefore, this game has partial information...... and symmetry constraints, which make the computation of Nash equilibria difficult. We show several undecidability results, and for bounded-memory strategies, we precisely characterize the complexity of computing pure Nash equilibria for qualitative objectives in this game model....

  16. Nash Equilibria in Symmetric Games with Partial Observation

    DEFF Research Database (Denmark)

    Bouyer, Patricia; Markey, Nicolas; Vester, Steen

    2014-01-01

    We investigate a model for representing large multiplayer games, which satisfy strong symmetry properties. This model is made of multiple copies of an arena; each player plays in his own arena, and can partially observe what the other players do. Therefore, this game has partial information...... and symmetry constraints, which make the computation of Nash equilibria difficult. We show several undecidability results, and for bounded-memory strategies, we precisely characterize the complexity of computing pure Nash equilibria (for qualitative objectives) in this game model....

  17. Recent progress in the relative equilibria of point vortices — In memoriam Hassan Aref

    DEFF Research Database (Denmark)

    Beelen, Peter; Brøns, Morten; Krishnamurthy, Vikas S.

    2013-01-01

    Hassan Aref, who sadly passed away in 2011, was one of the world's leading researchers in the dynamics and equilibria of point vortices. We review two problems on the subject of point vortex relative equilibria in which he was engaged at the time of his death: bilinear relative equilibria...

  18. Correlation and prediction of ion exchange equilibria on weak-acid resins by means of the surface complex formation model

    International Nuclear Information System (INIS)

    Horst, J.

    1988-11-01

    The present work summarizes investigations of the equilibrium of the exchange of protons, copper, zinc, calcium, magnesium and sodium ions on two weak-acid exchange resins in hydrochloric and carbonic acid bearing solutions at 25 0 C. The description of the state of equilibrium between resin and solution is based on the individual chemical equilibria which have to be adjusted simultaneously. The equilibrium in the liquid phase is described by the mass action law and the condition of electroneutrality using activity coefficients calculated according to the theory of Debye and Hueckel. The exchange equilibria are described by means of a surface complex formation model, which was developed by Davis, James and Leckie for activated aluminia and which has been applied to weak-acid resins. The model concept assumes the resin as a plane surface in which the functional groups are distributed uniformly. (orig./RB) [de

  19. Evaluation of a Mathematical Model for Single Component Adsorption Equilibria with Reference to the Prediction of Multicomponent Adsorption Equilibria

    DEFF Research Database (Denmark)

    Krøll, Annette Elisabeth; Marcussen, Lis

    1997-01-01

    An equilibrium equation for pure component adsorption is compared to experiments and to the vacancy solution theory. The investigated equilibrium equation is a special case of a model for prediction of multicomponent adsorption equilibria.The vacancy solution theory for multicomponent systems...... requires binary experimental data for determining the interaction parameters of the Wilson equation; thus a large number of experiments are needed. The multicomponent equilibria model which is investigated for single component systems in this work is based on pure component data only. This means...... that the requirement for experimental data is reduced significantly.The two adsorption models are compared, using experimental pure gas adsorption data found in literature. The results obtained by the models are in close agreement for pure component equilibria and they give a good description of the experimental data...

  20. Influence of vanadium doping on the electrochemical behaviour of MnO{sub 2} rutile; Influence du dopage par le vanadium sur le comportement electrochimique de MnO{sub 2} rutile

    Energy Technology Data Exchange (ETDEWEB)

    Delmas, C. [Centre National de la Recherche Scientifique (CNRS), 33 - Pessac (France). Institut de Chimie de la Matiere Condensee de Bordeaux; Capitaine, F.; Majastre [Bollore Technologies, 29 - Quimper (France); Baudry, P. [Electricite de France, 77 - Moret sur Loing (France). Direction des Etudes et Recherches

    1996-12-31

    Vanadium doped manganese bi-oxide has been obtained from a solution containing both cations. The X-ray diffraction of this material indicates a rutile-type phase but the enlargement of some lines supports the existence of several lattice defects. Also the particle size of the doped material is significantly smaller than the one of the non-doped material obtained in the same conditions. The presence of pentavalent vanadium inside the lattice leads to a small amount of trivalent manganese. Electron microscopy shows the existence of defects which have a tendency of becoming well-ordered and to stabilize a sur-structure. At ambient temperature, the electrochemical behaviour of doped manganese bi-oxide is greatly improved when compared to the non-doped phase. This behaviour is due to the presence of numerous lattice defects and to the smaller size of crystallites. In polymer batteries, the behaviour is similar the one of the non-doped material for which the kinetics performances are improved by the cycling at 100 deg. C. Abstract only. (J.S.)

  1. Influence of vanadium doping on the electrochemical behaviour of MnO{sub 2} rutile; Influence du dopage par le vanadium sur le comportement electrochimique de MnO{sub 2} rutile

    Energy Technology Data Exchange (ETDEWEB)

    Delmas, C [Centre National de la Recherche Scientifique (CNRS), 33 - Pessac (France). Institut de Chimie de la Matiere Condensee de Bordeaux; Capitaine, F; Majastre, [Bollore Technologies, 29 - Quimper (France); Baudry, P [Electricite de France, 77 - Moret sur Loing (France). Direction des Etudes et Recherches

    1997-12-31

    Vanadium doped manganese bi-oxide has been obtained from a solution containing both cations. The X-ray diffraction of this material indicates a rutile-type phase but the enlargement of some lines supports the existence of several lattice defects. Also the particle size of the doped material is significantly smaller than the one of the non-doped material obtained in the same conditions. The presence of pentavalent vanadium inside the lattice leads to a small amount of trivalent manganese. Electron microscopy shows the existence of defects which have a tendency of becoming well-ordered and to stabilize a sur-structure. At ambient temperature, the electrochemical behaviour of doped manganese bi-oxide is greatly improved when compared to the non-doped phase. This behaviour is due to the presence of numerous lattice defects and to the smaller size of crystallites. In polymer batteries, the behaviour is similar the one of the non-doped material for which the kinetics performances are improved by the cycling at 100 deg. C. Abstract only. (J.S.)

  2. Solid-state poly(ethylene glycol)-polyurethane/polymethylmethacrylate/rutile TiO2 nanofiber composite electrolyte-correlation between morphology and conducting properties

    International Nuclear Information System (INIS)

    Chilaka, Naresh; Ghosh, Sutapa

    2012-01-01

    Highlights: ► Semi IPN composite of PEG-PU/PMMA with different wt% of rutile TiO 2 is synthesized. ► Formation of nanocomposite is confirmed by SEM, XRD and IR spectroscopic analysis. ► DSC and TGA confirmed the enhanced thermal stability of the composite. ► Composite with 18 wt% rutile TiO 2 is found to be the best conducting material. - Abstract: A series of lithium electrolyte materials based on hybrid of semi Inter penetrating Polymer Network of [poly(ethylene glycol)-polyurethane-polymethylmethacrylate] [60:40] and TiO 2 nanofibers is described. TiO 2 nanofibers are made by simple solvothermal procedure. Rutile phase of TiO 2 and its fibrous morphology are confirmed by X-ray diffraction pattern and scanning electron microscopy image respectively. Semi Inter penetrating Polymer Network of polyethylene glycol-polyurethane/polymethylmethacrylate with LiClO 4 and its nanocomposite with different weight percent of TiO 2 nano fibers have been synthesized. The formation of Inter penetrating Polymer Network and its amorphous nature are confirmed by Fourier transform infrared spectra, X-ray diffraction pattern and differential scanning calorimetry results. Thermo gravimetric analysis shows enhanced thermal stability of the composite compared to the semi Inter penetrating Polymer Network system. The electrical characterizations of the nanocomposites are done by current–voltage (I–V) measurements and impedance spectroscopy. These results confirm that incorporation of TiO 2 nanofibers by 18% enhances the conductivity of the Inter penetrating Polymer Network system by ten times . The nanoscale structure of the inorganic material is found to be responsible for the bulk properties of the system, especially those that differ from the properties of similar, pure salt-in-polymer electrolytes. Further differential scanning calorimetry, scanning electron microscopy and impedance data confirm the presence of two polymeric phases in the semi Inter penetrating Polymer

  3. Searching for new TiO2 crystal phases with better photoactivity

    International Nuclear Information System (INIS)

    Shang, Cheng; Zhao, Wei-Na; Liu, Zhi-Pan

    2015-01-01

    Using the recently developed stochastic surface walking global optimization method, this work explores the potential energy surface of TiO 2 crystals aiming to search for likely phases with higher photocatalytic activity. Five new phases of TiO 2 are identified and the lowest energy phase transition pathways connecting to the most abundant phases (rutile and anatase) are determined. Theory shows that a high-pressure phase, α-PbO 2 -like form (TiO 2 II) acts as the key intermediate in between rutile and anatase. The phase transition of anatase to rutile belongs to the diffusionless Martensitic phase transition, occurring through a set of habit planes, rutile(101)//TiO 2 II(001), and TiO 2 II(100)//anatase(112). With regard to the photocatalytic activity, three pure phases (#110, pyrite and fluorite) are found to possess the band gap narrower than rutile, but they are unstable at the low-pressure condition. Instead, a mixed anatase-TiO 2 II phase is found to have good stability and narrower band gap than both parent phases. Because of the phase separation, the mixed phase is also expected to improve the photocatalytic performance by reducing the probability of the electron-hole pair recombination. (paper)

  4. Stochastic Equilibria under Imprecise Deviations in Terminal-Reward Concurrent Games

    Directory of Open Access Journals (Sweden)

    Patricia Bouyer

    2016-09-01

    Full Text Available We study the existence of mixed-strategy equilibria in concurrent games played on graphs. While existence is guaranteed with safety objectives for each player, Nash equilibria need not exist when players are given arbitrary terminal-reward objectives, and their existence is undecidable with qualitative reachability objectives (and only three players. However, these results rely on the fact that the players can enforce infinite plays while trying to improve their payoffs. In this paper, we introduce a relaxed notion of equilibria, where deviations are imprecise. We prove that contrary to Nash equilibria, such (stationary equilibria always exist, and we develop a PSPACE algorithm to compute one.

  5. A Numerical Algorithm to find All Scalar Feedback Nash Equilibria

    NARCIS (Netherlands)

    Engwerda, J.C.

    2013-01-01

    Abstract: In this note we generalize a numerical algorithm presented in [9] to calculate all solutions of the scalar algebraic Riccati equations that play an important role in finding feedback Nash equilibria of the scalar N-player linear affine-quadratic differential game. The algorithm is based on

  6. Computing Proper Equilibria of Zero-Sum Games

    DEFF Research Database (Denmark)

    Miltersen, Peter Bro; Sørensen, Troels Bjerre

    2007-01-01

    We show that a proper equilibrium of a matrix game can be found in polynomial time by solving a linear (in the number of pure strategies of the two players) number of linear programs of roughly the same dimensions as the standard linear programs describing the Nash equilibria of the game....

  7. Shallow-water vortex equilibria and their stability

    Energy Technology Data Exchange (ETDEWEB)

    Plotka, H; Dritschel, D G, E-mail: hanna@mcs.st-andrews.ac.uk, E-mail: dgd@mcs.st-andrews.ac.uk [School of Mathematics and Statistics, University of St Andrews, North Haugh, St. Andrews KY16 9SS (United Kingdom)

    2011-12-22

    We first describe the equilibrium form and stability of steadily-rotating simply-connected vortex patches in the single-layer quasi-geostrophic model of geophysical fluid dynamics. This model, valid for rotating shallow-water flow in the limit of small Rossby and Froude numbers, has an intrinsic length scale L{sub D} called the 'Rossby deformation length' relating the strength of stratification to that of the background rotation rate. Specifically, L{sub D} = c/f where c={radical}gH is a characteristic gravity-wave speed, g is gravity (or 'reduced' gravity in a two-layer context where one layer is infinitely deep), H is the mean active layer depth, and f is the Coriolis frequency (here constant). We next introduce ageostrophic effects by using the full shallow-water model to generate what we call 'quasi-equilibria'. These equilibria are not strictly steady, but radiate such weak gravity waves that they are steady for all practical purposes. Through an artificial ramping procedure, we ramp up the potential vorticity anomaly of the fluid particles in our quasi-geostrophic equilibria to obtain shallow-water quasi-equilibria at finite Rossby number. We show a few examples of these states in this paper.

  8. Asset pricing puzzles explained by incomplete Brownian equilibria

    DEFF Research Database (Denmark)

    Christensen, Peter Ove; Larsen, Kasper

    We examine a class of Brownian based models which produce tractable incomplete equilibria. The models are based on finitely many investors with heterogeneous exponential utilities over intermediate consumption who receive partially unspanned income. The investors can trade continuously on a finit...... markets. Consequently, our model can simultaneously help explaining the risk-free rate and equity premium puzzles....

  9. Field line diversion properties of finite β Helias equilibria

    International Nuclear Information System (INIS)

    Hayashi, T.; Schwenn, U.; Strumberger, E.

    1992-03-01

    The diversion properties of the magnetic field outside the last closed magnetic surface of a Helias stellarator configuration are investigated for finite β-equilibria. The results support a divertor concept which has been developed from the diversion properties of the corresponding vacuum field. Cross-field transport is simulated by a simplified scrape-off layer (SOL) model. (author)

  10. From Singularity Theory to Finiteness of Walrasian Equilibria

    DEFF Research Database (Denmark)

    Castro, Sofia B.S.D.; Dakhlia, Sami F.; Gothen, Peter

    The paper establishes that for an open and dense subset of smooth exchange economies, the number of Walrasian equilibria is finite. In particular, our results extend to non-regular economies; it even holds when restricted to the subset of critical ones. The proof rests on concepts from singularity...... theory....

  11. Close pairs of relative equilibria for identical point vortices

    DEFF Research Database (Denmark)

    Dirksen, Tobias; Aref, Hassan

    2011-01-01

    Numerical solution of the classical problem of relative equilibria for identical point vortices on the unbounded plane reveals configurations that are very close to the analytically known, centered, symmetrically arranged, nested equilateral triangles. New numerical solutions of this kind are fou...

  12. On the relationship between rutile/anatase ratio and the nature of defect states in sub-100 nm TiO2 nanostructures: experimental insights

    KAUST Repository

    Soliman, Moamen M.

    2018-02-02

    Black TiO2 is being widely investigated due to its superior optical activity and potential applications in photocatalytic hydrogen generation. Herein, the limitations of the hydrogenation process of TiO2 nanostructures are unraveled by exploiting the fundamental tradeoffs affecting the overall efficiency of the water splitting process. To control the nature and concentration of defect states, different reduction rates are applied to sub-100 nm TiO2 nanotubes, chosen primarily for their superiority over their long counterparts. X-Ray Photoelectron Spectroscopy disclosed changes in the stoichiometry of TiO2 with the reduction rate. UV-vis and Raman spectra showed that high reduction rates promote the formation of the rutile phase in TiO2, which is inactive towards water splitting. Furthermore, electrochemical analysis revealed that such high rates induce a higher concentration of localized electronic defect states that hinder the water splitting performance. Finally, incident photon-to-current conversion efficiency (IPCE) highlighted the optimum reduction rate that attains a relatively lower defect concentration as well as lower rutile content, thereby achieving the highest conversion efficiency.

  13. Modification of the microstructure and electronic properties of rutile TiO_2 thin films with 79 MeV Br ion irradiation

    International Nuclear Information System (INIS)

    Rath, Haripriya; Dash, P.; Singh, U.P.; Avasthi, D.K.; Kanjilal, D.; Mishra, N.C.

    2015-01-01

    Modifications induced by 79 MeV Br ions in rutile titanium dioxide thin films, synthesized by dc magnetron sputtering are presented. Irradiations did not induce any new XRD peak corresponding to any other phase. The area and the width of the XRD peaks were considerably affected by irradiation, and peaks shifted to lower angles. But the samples retained their crystallinity at the highest fluence (1 × 10"1"3 ions cm"−"2) of irradiation even though the electronic energy loss of 79 MeV Br ions far exceeds the reported threshold value for amorphization of rutile TiO_2. Fitting of the fluence dependence of the XRD peak area to Poisson equation yielded the radius of ion tracks as 2.4 nm. Ion track radius obtained from the simulation based on the thermal spike model matches closely with that obtained from the fluence dependence of the area under XRD peaks. Williamson–Hall analysis of the XRD spectra indicated broadening and shifting of the peaks are a consequence of irradiation induced defect accumulation leading to microstrains, as was also indicated by Raman and UV–Visible absorption study.

  14. Quantification of rutile in anatase by means of X-ray diffraction technique; Cuantificacion de rutilo en anatasa por medio de la tecnica de difraccion

    Energy Technology Data Exchange (ETDEWEB)

    Macias B, L.R.; Palacios G, J.; Garcia C, R.M. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    1999-07-01

    In this work, making use of the X-ray diffraction technique, it was determined the quantification of two phases which are mixed in a crystalline sample of rutile and anatase also it is indicated the method to proceed in its evaluation, so that in the end it will be had as result of a semi-quantitative analysis of the phases that are found in the sample. The conclusion is that this method performs in samples which are presented as powders and since the different parameters with which they must be fulfilled then this should not be called quantitative but semi-quantitative and it has a margin of error in its evaluation. (Author)

  15. Comment on Parts 1 and 2 of the Series “Electric Double Layer at the Rutile (110) Surface”

    Czech Academy of Sciences Publication Activity Database

    Předota, Milan; Vlček, Lukáš

    2007-01-01

    Roč. 111, č. 5 (2007), s. 1245-1247 ISSN 1520-6106 Institutional research plan: CEZ:AV0Z40720504 Keywords : rutile * simulation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.086, year: 2007

  16. On Nash-Equilibria of Approximation-Stable Games

    Science.gov (United States)

    Awasthi, Pranjal; Balcan, Maria-Florina; Blum, Avrim; Sheffet, Or; Vempala, Santosh

    One reason for wanting to compute an (approximate) Nash equilibrium of a game is to predict how players will play. However, if the game has multiple equilibria that are far apart, or ɛ-equilibria that are far in variation distance from the true Nash equilibrium strategies, then this prediction may not be possible even in principle. Motivated by this consideration, in this paper we define the notion of games that are approximation stable, meaning that all ɛ-approximate equilibria are contained inside a small ball of radius Δ around a true equilibrium, and investigate a number of their properties. Many natural small games such as matching pennies and rock-paper-scissors are indeed approximation stable. We show furthermore there exist 2-player n-by-n approximation-stable games in which the Nash equilibrium and all approximate equilibria have support Ω(log n). On the other hand, we show all (ɛ,Δ) approximation-stable games must have an ɛ-equilibrium of support O(Δ^{2-o(1)}/ɛ2{log n}), yielding an immediate n^{O(Δ^{2-o(1)}/ɛ^2log n)}-time algorithm, improving over the bound of [11] for games satisfying this condition. We in addition give a polynomial-time algorithm for the case that Δ and ɛ are sufficiently close together. We also consider an inverse property, namely that all non-approximate equilibria are far from some true equilibrium, and give an efficient algorithm for games satisfying that condition.

  17. Behavior of magnetic islands in 3D MHD equilibria of helical devices

    International Nuclear Information System (INIS)

    Hayashi, T.; Sato, T.; Nakajima, N.

    1994-09-01

    Magnetic island formation in three-dimensional finite-β equilibria in the H-1 Heliac is studied by using the HINT code. It is found that the size of a dangerous island should increase with β but that a destruction of the equilibrium at low β is avoided because the rotational transform evolves to exclude the rational surface concerned. At higher β there is evidence of near-resonant flux surface deformations which may lead to an equilibrium limit. A reconnected equilibrium at still higher β exhibits a double island structure which is similar to homoclinic phase portraits which have been observed after separatrix reconnection in Hamiltonian systems. Physical mechanism of the island formation in finite-β helical equilibria is investigated to confirm there are cases where the global effect of the Pfirsch-Schlueter currents is important. The earlier theory is extended to elucidate the occurence of the complete self-healing of island when the resistive interchange criterion satisfied. (author)

  18. Stability of nonlinear Vlasov-Poisson equilibria through spectral deformation and Fourier-Hermite expansion.

    Science.gov (United States)

    Siminos, Evangelos; Bénisti, Didier; Gremillet, Laurent

    2011-05-01

    We study the stability of spatially periodic, nonlinear Vlasov-Poisson equilibria as an eigenproblem in a Fourier-Hermite basis (in the space and velocity variables, respectively) of finite dimension, N. When the advection term in the Vlasov equation is dominant, the convergence with N of the eigenvalues is rather slow, limiting the applicability of the method. We use the method of spectral deformation introduced by Crawford and Hislop [Ann. Phys. (NY) 189, 265 (1989)] to selectively damp the continuum of neutral modes associated with the advection term, thus accelerating convergence. We validate and benchmark the performance of our method by reproducing the kinetic dispersion relation results for linear (spatially homogeneous) equilibria. Finally, we study the stability of a periodic Bernstein-Greene-Kruskal mode with multiple phase-space vortices, compare our results with numerical simulations of the Vlasov-Poisson system, and show that the initial unstable equilibrium may evolve to different asymptotic states depending on the way it was perturbed. © 2011 American Physical Society

  19. Experimental vapor-liquid equilibria data for binary mixtures of xylene isomers

    Directory of Open Access Journals (Sweden)

    W.L. Rodrigues

    2005-09-01

    Full Text Available Separation of aromatic C8 compounds by distillation is a difficult task due to the low relative volatilities of the compounds and to the high degree of purity required of the final commercial products. For rigorous simulation and optimization of this separation, the use of a model capable of describing vapor-liquid equilibria accurately is necessary. Nevertheless, experimental data are not available for all binaries at atmospheric pressure. Vapor-liquid equilibria data for binary mixtures were isobarically obtained with a modified Fischer cell at 100.65 kPa. The vapor and liquid phase compositions were analyzed with a gas chromatograph. The methodology was initially tested for cyclo-hexane+n-heptane data; results obtained are similar to other data in the literature. Data for xylene binary mixtures were then obtained, and after testing, were considered to be thermodynamically consistent. Experimental data were regressed with Aspen Plus® 10.1 and binary interaction parameters were reported for the most frequently used activity coefficient models and for the classic mixing rules of two cubic equations of state.

  20. Controlled formation of anatase and rutile TiO2 thin films by reactive magnetron sputtering

    OpenAIRE

    Rafieian, Damon; Ogieglo, Wojciech; Savenije, T.J.; Lammertink, Rob G H

    2015-01-01

    We discuss the formation of TiO2 thin films via DC reactive magnetron sputtering. The oxygen concentration during sputtering proved to be a crucial parameter with respect to the final film structure and properties. The initial deposition provided amorphous films that crystallise upon annealing to anatase or rutile, depending on the initial sputtering conditions. Substoichiometric films (TiOx), obtained by sputtering at relatively low oxygen concentration, formed rutile upon annealing in air, ...