Evaluation of the stability and precipitation behavior of G phase in dual-phase stainless steels by thermodynamic calculations

International Nuclear Information System (INIS)

Horiuchi, Toshiaki; Ito, Shota; Minamoto, Satoshi

2017-01-01

Degradation of dual-phase stainless steel in nuclear power plants due to thermal ageing during long-term use is an important issue. This occurs mainly due to breakdown of the ferrite phase as a result of spinodal decomposition, followed by clustering or precipitation of the intermetallic G-phase compound, 'Ni 16 Si 7 Mn 6 ', which consists primarily of Ni, Si and Mn. The degradation mechanism is complicated because both radiation effects and thermal ageing simultaneously occur. However, only limited information is available concerning this phenomenon, and particularly regarding precipitation of the G phase. In the present study, thermodynamic equilibrium calculations were carried out for two types of dual-phase stainless steel (weld metal and cast steel) to evaluate the influence of the temperature and constituent elements on the stability of the G phase. The calculations were performed using the Thermo-Calc program with the thermodynamic database, FE-DATA (ver. 6). Precipitation of the G phase was investigated using the TC-PRISMA precipitation module together with the MOB2 diffusion database. It was found that for both types of steel, the G phase contains not only Ni, Si and Mn, but also small amounts of Fe and Cr. The stability of the G phase is dependent on the Ni, Mn, Cr, Si and Mo content in the original steel, and particularly on that of the latter two elements. Due to its higher Si content, the G phase was shown to be more stable in cast steel than in weld metal. (author)

Interfacial engineering of solution-processed Ni nanochain-SiO{sub x} (x < 2) cermets towards thermodynamically stable, anti-oxidation solar selective absorbers

Energy Technology Data Exchange (ETDEWEB)

Yu, Xiaobai; Wang, Xiaoxin; Liu, Jifeng, E-mail: Jifeng.Liu@dartmouth.edu [Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, New Hampshire 03755 (United States); Zhang, Qinglin [Department of Chemical and Materials Engineering, University of Kentucky, 177 F. Paul Anderson Tower, Lexington, Kentucky 40506 (United States)

2016-04-07

Cermet solar thermal selective absorber coatings are an important component of high-efficiency concentrated solar power (CSP) receivers. The oxidation of the metal nanoparticles in cermet solar absorbers is a great challenge for vacuum-free operation. Recently, we have demonstrated that oxidation is kinetically retarded in solution processed, high-optical-performance Ni nanochain-SiO{sub x} cermet system compared to conventional Ni-Al{sub 2}O{sub 3} system when annealed in air at 450–600 °C for several hours. However, for long-term, high-temperature applications in CSP systems, thermodynamically stable antioxidation behavior is highly desirable, which requires new mechanisms beyond kinetically reducing the oxidation rate. Towards this goal, in this paper, we demonstrate that pre-operation annealing of Ni nanochain-SiO{sub x} cermets at 900 °C in N{sub 2} forms the thermodynamically stable orthorhombic phase of NiSi at the Ni/SiO{sub x} interfaces, leading to self-terminated oxidation at 550 °C in air due to this interfacial engineering. In contrast, pre-operation annealing at a lower temperature of 750 °C in N{sub 2} (as conducted in our previous work) cannot achieve interfacial NiSi formation directly, and further annealing in air at 450–600 °C for >4 h only leads to the formation of the less stable (metastable) hexagonal phase of NiSi. Therefore, the high-temperature pre-operation annealing is critical to form the desirable orthorhombic phase of NiSi at Ni/SiO{sub x} interfaces towards thermodynamically stable antioxidation behavior. Remarkably, with this improved interfacial engineering, the oxidation of 80-nm-diameter Ni nanochain-SiO{sub x} saturates after annealing at 550 °C in air for 12 h. Additional annealing at 550 °C in air for as long as 20 h (i.e., 32 h air annealing at >550 °C in total) has almost no further impact on the structural or optical properties of the coatings, the latter being very sensitive to any

Thermodynamics of the hot BIon

DEFF Research Database (Denmark)

Grignani, Gianluca; Harmark, Troels; Marini, Andrea

2011-01-01

We investigate the thermodynamics of the recently obtained nite temperature BIon solution of arXiv:1012.1494, focusing on two aspects. The first concerns comparison of the free energy of the three available phases for the finite temperature brane-antibrane wormhole configuration. Based on this we...... propose a heuristic picture for the dynamics of the phases that involves a critical temperature below which a stable phase exists. This stable phase is the finite temperature analogue of the thin throat branch of the extremal brane anti-brane wormhole configuration. The second aspect that we consider...

Thermodynamic study of sodium-iron oxides. Part 2. Ternary phase diagram of the Na-Fe-O system

International Nuclear Information System (INIS)

Huang, Jintao; Furukawa, Tomohiro; Aoto, Kazumi

2003-01-01

Studies on ternary phase diagrams of the Na-Fe-O system have been carried out from the thermodynamic point of view. Thermodynamic data of main ternary Na-Fe oxides Na 4 FeO 3 (s), Na 3 FeO 3 (s), Na 5 FeO 4 (s) and Na 8 Fe 2 O 7 (s) have been assessed. A user database has been created by reviewing literature data together with recent DSC and vapor pressure measurements by the present authors. New ternary phase diagrams of the Na-Fe-O system have been constructed from room temperature to 1000K. Stable conditions of the ternary oxides at 800K were presented in predominance diagram as functions of oxygen pressure and sodium pressure

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.

Entropy stable modeling of non-isothermal multi-component diffuse-interface two-phase flows with realistic equations of state

KAUST Repository

Kou, Jisheng

2018-02-25

In this paper, we consider mathematical modeling and numerical simulation of non-isothermal compressible multi-component diffuse-interface two-phase flows with realistic equations of state. A general model with general reference velocity is derived rigorously through thermodynamical laws and Onsager\\'s reciprocal principle, and it is capable of characterizing compressibility and partial miscibility between multiple fluids. We prove a novel relation among the pressure, temperature and chemical potentials, which results in a new formulation of the momentum conservation equation indicating that the gradients of chemical potentials and temperature become the primary driving force of the fluid motion except for the external forces. A key challenge in numerical simulation is to develop entropy stable numerical schemes preserving the laws of thermodynamics. Based on the convex-concave splitting of Helmholtz free energy density with respect to molar densities and temperature, we propose an entropy stable numerical method, which solves the total energy balance equation directly, and thus, naturally satisfies the first law of thermodynamics. Unconditional entropy stability (the second law of thermodynamics) of the proposed method is proved by estimating the variations of Helmholtz free energy and kinetic energy with time steps. Numerical results validate the proposed method.

Entropy stable modeling of non-isothermal multi-component diffuse-interface two-phase flows with realistic equations of state

KAUST Repository

Kou, Jisheng; Sun, Shuyu

2018-01-01

In this paper, we consider mathematical modeling and numerical simulation of non-isothermal compressible multi-component diffuse-interface two-phase flows with realistic equations of state. A general model with general reference velocity is derived rigorously through thermodynamical laws and Onsager's reciprocal principle, and it is capable of characterizing compressibility and partial miscibility between multiple fluids. We prove a novel relation among the pressure, temperature and chemical potentials, which results in a new formulation of the momentum conservation equation indicating that the gradients of chemical potentials and temperature become the primary driving force of the fluid motion except for the external forces. A key challenge in numerical simulation is to develop entropy stable numerical schemes preserving the laws of thermodynamics. Based on the convex-concave splitting of Helmholtz free energy density with respect to molar densities and temperature, we propose an entropy stable numerical method, which solves the total energy balance equation directly, and thus, naturally satisfies the first law of thermodynamics. Unconditional entropy stability (the second law of thermodynamics) of the proposed method is proved by estimating the variations of Helmholtz free energy and kinetic energy with time steps. Numerical results validate the proposed method.

Modelling of phase diagrams and thermodynamic properties using Calphad method – Development of thermodynamic databases

Czech Academy of Sciences Publication Activity Database

Kroupa, Aleš

2013-01-01

Roč. 66, JAN (2013), s. 3-13 ISSN 0927-0256 R&D Projects: GA MŠk(CZ) OC08053 Institutional support: RVO:68081723 Keywords : Calphad method * phase diagram modelling * thermodynamic database development Subject RIV: BJ - Thermodynamics Impact factor: 1.879, year: 2013

Thermodynamic phase transition of a black hole in rainbow gravity

Directory of Open Access Journals (Sweden)

Zhong-Wen Feng

2017-09-01

Full Text Available In this letter, using the rainbow functions that were proposed by Magueijo and Smolin, we investigate the thermodynamics and the phase transition of rainbow Schwarzschild black hole. First, we calculate the rainbow gravity corrected Hawking temperature. From this modification, we then derive the local temperature, free energy, and other thermodynamic quantities in an isothermal cavity. Finally, we analyze the critical behavior, thermodynamic stability, and phase transition of the rainbow Schwarzschild black hole. The results show that the rainbow gravity can stop the Hawking radiation in the final stages of black holes' evolution and lead to the remnants of black holes. Furthermore, one can observe that the rainbow Schwarzschild black hole has one first-order phase transition, two second-order phase transitions, and three Hawking–Page-type phase transitions in the framework of rainbow gravity theory.

Thermodynamic stabilization of colloids

NARCIS (Netherlands)

Stol, R.J.; Bruyn, P.L. de

An analysis is given of the conditions necessary for obtaining a thermodynamically stable dispersion (TSD) of solid particles in a continuous aqueous solution phase. The role of the adsorption of potential-determining ions at the planar interface in lowering the interfacial free energy (γ) to

High-pressure phase relations and thermodynamic properties of CaAl 4Si 2O 11 CAS phase

Science.gov (United States)

Akaogi, M.; Haraguchi, M.; Yaguchi, M.; Kojitani, H.

2009-03-01

Phase relations in CaAl4Si2O11 were examined at 12-23 GPa and 1000-1800 °C by multianvil experiments. A three-phase mixture of grossular, kyanite and corundum is stable below about 13 GPa at 1000-1800 °C. At higher pressure and at temperature below about 1200 °C, a mixture of grossular, stishovite and corundum is stable, indicating the decomposition of kyanite. Above about 1200 °C, CaAl4Si2O11 CAS phase is stable at pressure higher than about 13 GPa. The triple point is placed at 14.7 GPa and 1280 °C. The equilibrium boundary of formation of CAS phase from the mixture of grossular, kyanite and corundum has a small negative slope, and that from the mixture of grossular, stishovite and corundum has a strongly negative slope, while the decomposition boundary of kyanite has a small positive slope. Enthalpies of the transitions were measured by high-temperature drop-solution calorimetry. The enthalpy of formation of CaAl4Si2O11 CAS phase from the mixture of grossular, kyanite and corundum was 139.5 ± 15.6 kJ/mol, and that from the mixture of grossular, stishovite and corundum was 94.2 ± 15.4 kJ/mol. The transition boundaries calculated using the measured enthalpy data were consistent with those determined by the high-pressure experiments. The boundaries in this study are placed about 3 GPa higher in pressure and about 200 °C lower in temperature than those by Zhai and Ito [Zhai, S., Ito, E., 2008. Phase relations of CaAl4Si2O11 at high-pressure and high-temperature with implications for subducted continental crust into the deep mantle. Phys. Earth Planet. Inter. 167, 161-167]. Combining the thermodynamic data measured in this study with those in the literature, dissociation boundary of CAS phase into a mixture of Ca-perovskite, corundum and stishovite and that of grossular into Ca-perovskite plus corundum were calculated to further constrain the stability field of CAS phase. The result suggests that the stability of CAS phase would be limited at the bottom of

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

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.

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.

Determining Cloud Thermodynamic Phase from Micropulse Lidar Network Data

Science.gov (United States)

Lewis, Jasper R.; Campbell, James; Lolli, Simone; Tan, Ivy; Welton, Ellsworth J.

2017-01-01

Determining cloud thermodynamic phase is a critical factor in studies of Earth's radiation budget. Here we use observations from the NASA Micro Pulse Lidar Network (MPLNET) and thermodynamic profiles from the Goddard Earth Observing System, version 5 (GEOS-5) to distinguish liquid water, mixed-phase, and ice water clouds. The MPLNET provides sparse global, autonomous, and continuous measurements of clouds and aerosols which have been used in a number of scientific investigations to date. The use of a standardized instrument and a common suite of data processing algorithms with thorough uncertainty characterization allows for straightforward comparisons between sites. Lidars with polarization capabilities have recently been incorporated into the MPLNET project which allows, for the first time, the ability to infer a cloud thermodynamic phase. This presentation will look specifically at the occurrence of ice and mixed phase clouds in the temperature region of -10 C to -40 C for different climatological regions and seasons. We compare MPLNET occurrences of mixed-phase clouds to an historical climatology based on observations from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) spacecraft.

Thermodynamics and dynamics of the hard-sphere system: From stable to metastable states

Energy Technology Data Exchange (ETDEWEB)

Bomont, Jean-Marc, E-mail: jean-marc.bomont@univ-lorraine.fr; Bretonnet, Jean-Louis

2014-08-17

Highlights: • Three different scaling laws, devoted to transport properties of hard-sphere system, are investigated over a wide range of packing fractions. • A new semiempirical relation linking the transport properties to the excess pressure is derived. • The present relation allows to better understand the link between the thermodynamic and the dynamic properties of the hard-sphere system. - Abstract: A set of three different scaling laws is investigated, which are devoted to link the transport properties, i.e. diffusion coefficient, shear viscosity, bulk viscosity and thermal conductivity, to the thermodynamic properties for the athermal hard-sphere system, over the wider range of packing fraction covering the stable and metastable regimes. Except for the thermal conductivity, the Rosenfeld (1999) [15] relation is found to be applicable to the stable states while the Adam and Gibbs (1965) [24] relation holds well for the metastable states. In contrast, the modified Cohen and Turnbull (1959) [25] relation proposed here gives sound support for a universal scaling law connecting the dynamic and thermodynamic properties, over the domain of packing fraction including the stable and metastable states. In particular, it is found that the most relevant control parameter is not the excess entropy, but the logarithm derivative of the excess entropy with respect to the packing fraction. In the same context, the Stokes–Einstein relation between the diffusion coefficient and the shear viscosity is also examined. The possible violation of the Stokes–Einstein relation is investigated over a large domain of packing fractions.

Thermodynamics and dynamics of the hard-sphere system: From stable to metastable states

International Nuclear Information System (INIS)

Bomont, Jean-Marc; Bretonnet, Jean-Louis

2014-01-01

Highlights: • Three different scaling laws, devoted to transport properties of hard-sphere system, are investigated over a wide range of packing fractions. • A new semiempirical relation linking the transport properties to the excess pressure is derived. • The present relation allows to better understand the link between the thermodynamic and the dynamic properties of the hard-sphere system. - Abstract: A set of three different scaling laws is investigated, which are devoted to link the transport properties, i.e. diffusion coefficient, shear viscosity, bulk viscosity and thermal conductivity, to the thermodynamic properties for the athermal hard-sphere system, over the wider range of packing fraction covering the stable and metastable regimes. Except for the thermal conductivity, the Rosenfeld (1999) [15] relation is found to be applicable to the stable states while the Adam and Gibbs (1965) [24] relation holds well for the metastable states. In contrast, the modified Cohen and Turnbull (1959) [25] relation proposed here gives sound support for a universal scaling law connecting the dynamic and thermodynamic properties, over the domain of packing fraction including the stable and metastable states. In particular, it is found that the most relevant control parameter is not the excess entropy, but the logarithm derivative of the excess entropy with respect to the packing fraction. In the same context, the Stokes–Einstein relation between the diffusion coefficient and the shear viscosity is also examined. The possible violation of the Stokes–Einstein relation is investigated over a large domain of packing fractions

Thermodynamic analysis of (Ni, Fe)3Al formation by mechanical alloying

International Nuclear Information System (INIS)

Adabavazeh, Z.; Karimzadeh, F.; Enayati, M.H.

2012-01-01

Highlights: ► (Ni, Fe) 3 Al intermetallic compound was synthesized by mechanical alloying. ► We use a thermodynamic analysis to predict the more stable phase. ► We calculate the Gibbs free-energy changes by using extended Miedema model. ► The results of MA compared with thermodynamic analysis and showed a good agreement with it. - Abstract: (Ni, Fe) 3 Al intermetallic compound was synthesized by mechanical alloying (MA) of Ni, Fe and Al elemental powder mixtures of composition Ni 50 Fe 25 Al 25 . Phase transformation and microstructure characteristics of the alloy powders were investigated by X-ray diffraction (XRD). The results show that mechanical alloying resulted in a Ni (Al, Fe) solid solution. By continued milling, this structure transformed to the disordered (Ni, Fe) 3 Al intermetallic compound. A thermodynamic model developed on the basis of extended theory of Miedema is used to calculate the Gibbs free-energy changes. Final product of MA is a phase having minimal Gibbs free energy compared with other competing phases in Ni–Fe–Al system. However in Ni–Fe–Al system, the most stable phase at all compositions is intermetallic compound (not amorphous phase or solid solution). The results of MA were compared with thermodynamic analysis and revealed the leading role of thermodynamic on the formation of MA product prediction.

HP-67 calculator programs for thermodynamic data and phase diagram calculations

International Nuclear Information System (INIS)

Brewer, L.

1978-01-01

This report is a supplement to a tabulation of the thermodynamic and phase data for the 100 binary systems of Mo with the elements from H to Lr. The calculations of thermodynamic data and phase equilibria were carried out from 5000 0 K to low temperatures. This report presents the methods of calculation used. The thermodynamics involved is rather straightforward and the reader is referred to any advanced thermodynamic text. The calculations were largely carried out using an HP-65 programmable calculator. In this report, those programs are reformulated for use with the HP-67 calculator; great reduction in the number of programs required to carry out the calculation results

Secondary phases formed during nuclear waste glass-water interactions: Thermodynamic and derived properties

International Nuclear Information System (INIS)

McKenzie, W.F.

1992-08-01

The thermodynamic properties of secondary phases observed to form during nuclear waste glass-water interactions are of particular interest as it is with the application of these properties together with the thermodynamic properties of other solid phases, fluid phases, and aqueous species that one may predict the environmental consequences of introducing radionuclides contained in the glass into groundwater at a high-level nuclear waste repository. The validation of these predicted consequences can be obtained from laboratory experiments and field observations at natural analogue sites. The purpose of this report is to update and expand the previous compilation (McKenzie, 1991) of thermodynamic data retrieved from the literature and/or estimated for secondary phases observed to form (and candidate phases from observed chemical compositions) during nuclear waste glass-water interactions. In addition, this report includes provisionally recommended thermodynamic data of secondary phases

Thermodynamics of phase-separating nanoalloys: Single particles and particle assemblies

Science.gov (United States)

Fèvre, Mathieu; Le Bouar, Yann; Finel, Alphonse

2018-05-01

The aim of this paper is to investigate the consequences of finite-size effects on the thermodynamics of nanoparticle assemblies and isolated particles. We consider a binary phase-separating alloy with a negligible atomic size mismatch, and equilibrium states are computed using off-lattice Monte Carlo simulations in several thermodynamic ensembles. First, a semi-grand-canonical ensemble is used to describe infinite assemblies of particles with the same size. When decreasing the particle size, we obtain a significant decrease of the solid/liquid transition temperatures as well as a growing asymmetry of the solid-state miscibility gap related to surface segregation effects. Second, a canonical ensemble is used to analyze the thermodynamic equilibrium of finite monodisperse particle assemblies. Using a general thermodynamic formulation, we show that a particle assembly may split into two subassemblies of identical particles. Moreover, if the overall average canonical concentration belongs to a discrete spectrum, the subassembly concentrations are equal to the semi-grand-canonical equilibrium ones. We also show that the equilibrium of a particle assembly with a prescribed size distribution combines a size effect and the fact that a given particle size assembly can adopt two configurations. Finally, we have considered the thermodynamics of an isolated particle to analyze whether a phase separation can be defined within a particle. When studying rather large nanoparticles, we found that the region in which a two-phase domain can be identified inside a particle is well below the bulk phase diagram, but the concentration of the homogeneous core remains very close to the bulk solubility limit.

Thermodynamic properties of cesium in the gaseous phase

International Nuclear Information System (INIS)

Vargaftik, N.B.; Voljak, L.D.; Stepanov, V.G.

1985-01-01

Tables of the thermodynamic properties of caesium in the gaseous phase are presented for a wide range of temperature and pressure. The thermodynamic properties include: enthalpy, entropy, specific heat, specific volume, sound velocity and compressibility factor. The values have been calculated from pressure-volume-temperature measurements by various authors. Experimental apparatus to determine these measurements is described, together with an outline of the method employed to process the results, and the error estimates. (U.K.)

Nickel Solubility and Precipitation in Soils: A Thermodynamic Study

International Nuclear Information System (INIS)

Peltier, E.; Allada, R.; Navrotsky, A.; Sparks, D.

2006-01-01

The formation of mixed-metal-Al layered double hydroxide (LDH) phases similar to hydrotalcite has been identified as a significant mechanism for immobilization of trace metals in some environmental systems. These precipitate phases become increasingly stable as they age, and their formation may therefore be an important pathway for sequestration of toxic metals in contaminated soils. However, the lack of thermodynamic data for LDH phases makes it difficult to model their behavior in natural systems. In this work, enthalpies of formation for Ni LDH phases with nitrate and sulfate interlayers were determined and compared to recently published data on carbonate interlayer LDHs. Differences in the identity of the anion interlayer resulted in substantial changes in the enthalpies of formation of the LDH phases, in the order of increasing enthalpy carbonatethermodynamic properties of the LDH phases. Modeling results based on these thermodynamic data indicated that the formation of LDH phases on soil mineral substrates decreased Ni solubility compared to Ni(OH)2 over pH 5-9 when soluble Al is present in the soil substrate. Over time, both of these precipitate phases will transform to more stable Ni phyllosilicates

Calculation of thermodynamic properties using the random-phase approximation: alpha-N2

NARCIS (Netherlands)

Jansen, A.P.J.; Schoorl, R.

1988-01-01

The random-phase approximation (RPA) for molecular crystals is extended in order to calculate thermodynamic properties. A recursion formula for thermodynamic averages of products of mean-field excitation and deexcitation operators is derived. With this formula the thermodynamic average of any

Thermodynamics, phase transition and quasinormal modes with Weyl corrections

Energy Technology Data Exchange (ETDEWEB)

Mahapatra, Subhash [The Institute of Mathematical Sciences,Chennai 600113 (India)

2016-04-21

We study charged black holes in D dimensional AdS space, in the presence of four derivative Weyl correction. We obtain the black hole solution perturbatively up to first as well as second order in the Weyl coupling, and show that first law of black hole thermodynamics is satisfied in all dimensions. We study its thermodynamic phase transition and then calculate the quasinormal frequencies of the massless scalar field perturbation. We find that, here too, the quasinormal frequencies capture the essence of black hole phase transition. Few subtleties near the second order critical point are discussed.

Computer-aided construction and investigation of a thermodynamically stable mouth-dissolving film containing isoniazid

CSIR Research Space (South Africa)

Adeleke, Oluwatoyin A

2015-10-01

Full Text Available The purpose of this abstract is to design and characterize a thermodynamically stable mouth-dissolving film containing isoniazid employing in silico and in vitro techniques. Isoniazid (solubility = 140 mg/mL and log P = -0.64 at 25°C) is a first...

Stability, electronic and thermodynamic properties of aluminene from first-principles calculations

Energy Technology Data Exchange (ETDEWEB)

Yuan, Junhui [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Yu, Niannian [School of Science, Wuhan University of Technology, Wuhan, Hubei 430070 (China); Xue, Kanhao, E-mail: xkh@hust.edu.cn [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Miao, Xiangshui [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

2017-07-01

Highlights: • We have predicted two NEW stable phases of atomic layer aluminum, buckled and 8-Pmmn aluminene. • We have revealed the electronic structures and bonding characteristics of aluminene. • Thermodynamic properties of aluminene were investigated based on phonon properties. - Abstract: Using first-principles calculations based on density functional theory (DFT), we have investigated the structure stability and electronic properties of both buckled and 8-Pmmn phase aluminene. Phonon dispersion analysis reveals that the buckled and 8-Pmmn aluminene are dynamically stable. The band structure shows that both the buckled and 8-Pmmn aluminene exhibit metallic behavior. Finally, the thermodynamic properties are investigated based on phonon properties.

Stability, electronic and thermodynamic properties of aluminene from first-principles calculations

International Nuclear Information System (INIS)

Yuan, Junhui; Yu, Niannian; Xue, Kanhao; Miao, Xiangshui

2017-01-01

Highlights: • We have predicted two NEW stable phases of atomic layer aluminum, buckled and 8-Pmmn aluminene. • We have revealed the electronic structures and bonding characteristics of aluminene. • Thermodynamic properties of aluminene were investigated based on phonon properties. - Abstract: Using first-principles calculations based on density functional theory (DFT), we have investigated the structure stability and electronic properties of both buckled and 8-Pmmn phase aluminene. Phonon dispersion analysis reveals that the buckled and 8-Pmmn aluminene are dynamically stable. The band structure shows that both the buckled and 8-Pmmn aluminene exhibit metallic behavior. Finally, the thermodynamic properties are investigated based on phonon properties.

Stable Low Cloud Phase II: Nocturnal Event Study

Science.gov (United States)

Bauman, William H., III; Barrett, Joe, III

2007-01-01

This report describes the work done by the Applied Meteorology Unit (AMU) in developing a database of nights that experienced rapid (formation in a stable atmosphere, resulting in ceilings at the Shuttle Landing Facility (TTS) that violated Space Shuttle Flight Rules (FR). This work is the second phase of a similar AMU task that examined the same phenomena during the day. In the first phase of this work, the meteorological conditions favoring the rapid formation of low ceilings include the presence of any inversion below 8000 ft, high relative humidity (RH) beneath the inversion and a clockwise turning of the winds from the surface to the middle troposphere (-15000 ft). The AMU compared and contrasted the atmospheric and thermodynamic conditions between nights with rapid low ceiling formation and nights with low ceilings resulting from other mechanisms. The AMU found that there was little to discern between the rapidly-forming ceiling nights and other low ceiling nights at TTS. When a rapid development occurred, the average RH below the inversions was 87% while non-events had an average RH of 79%. One key parameter appeared to be the vertical wind profile in the Cape Canaveral, FL radiosonde (XMR) sounding. Eighty-three percent of the rapid development events had veering winds with height from the surface to the middle troposphere (-15,000 ft) while 61% of the non-events had veering winds with height. Veering winds indicate a warm-advection regime, which supports large-scale rising motion and ultimately cloud formation in a moist environment. However, only six of the nights (out of 86 events examined) with low cloud ceilings had an occurrence of rapidly developing ceilings. Since only 7% rapid development events were observed in this dataset, it is likely that rapid low cloud development is not a common occurrence during the night, or at least not as common as during the day. In the AMU work on the daytime rapid low cloud development (Case and Wheeler 2005), nearly

Nonequilibrium thermodynamic fluctuations and phase transition in black holes

International Nuclear Information System (INIS)

Su, R.; Cai, R.; Yu, P.K.N.

1994-01-01

Landau nonequilibrium fluctuation and phase transition theory is applied to the discussion of the phase transition of black holes. Some second moments of relevant thermodynamical quantities for Kerr-Newman black holes are estimated. A theorem governing the divergence of some second moments and the occurrence of the phase transition in black holes is given

Thermodynamic study of CVD-ZrO2 phase diagrams

International Nuclear Information System (INIS)

Torres-Huerta, A.M.; Vargas-Garcia, J.R.; Dominguez-Crespo, M.A.; Romero-Serrano, J.A.

2009-01-01

Chemical vapor deposition (CVD) of zirconium oxide (ZrO 2 ) from zirconium acetylacetonate Zr(acac) 4 has been thermodynamically investigated using the Gibbs' free energy minimization method and the FACTSAGE program. Thermodynamic data Cp o , ΔH o and S o for Zr(acac) 4 have been estimated using the Meghreblian-Crawford-Parr and Benson methods because they are not available in the literature. The effect of deposition parameters, such as temperature and pressure, on the extension of the region where pure ZrO 2 can be deposited was analyzed. The results are presented as calculated CVD stability diagrams. The phase diagrams showed two zones, one of them corresponds to pure monoclinic phase of ZrO 2 and the other one corresponds to a mix of monoclinic phase of ZrO 2 and graphite carbon.

Thermodynamics and kinetics of phase transformation in intercalation battery electrodes - phenomenological modeling

Energy Technology Data Exchange (ETDEWEB)

Lai Wei, E-mail: laiwei@msu.ed [Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI 48824 (United States); Ciucci, Francesco [Heidelberg Graduate School of Mathematical and Computational Methods for the Sciences, University of Heidelberg, INF 368 D - 69120 Heidelberg (Germany)

2010-12-15

Thermodynamics and kinetics of phase transformation in intercalation battery electrodes are investigated by phenomenological models which include a mean-field lattice-gas thermodynamic model and a generalized Poisson-Nernst-Planck equation set based on linear irreversible thermodynamics. The application of modeling to a porous intercalation electrode leads to a hierarchical equivalent circuit with elements of explicit physical meanings. The equivalent circuit corresponding to the intercalation particle of planar, cylindrical and spherical symmetry is reduced to a diffusion equation with concentration dependent diffusivity. The numerical analysis of the diffusion equation suggests the front propagation behavior during phase transformation. The present treatment is also compared with the conventional moving boundary and phase field approaches.

Ab-initio study of phase stability, elastic and thermodynamic properties of AlY alloy under pressure

Energy Technology Data Exchange (ETDEWEB)

Zhou, Dawei [College of Physics and Electronic Engineering, Nanyang Normal University, Nanyang 473061 (China); Su, Taichao [Institute of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo 454000 (China); Song, Haizhen; Lu, Cheng; Zhong, Zhiguo; Lu, Zhiwen [College of Physics and Electronic Engineering, Nanyang Normal University, Nanyang 473061 (China); Pu, Chunying, E-mail: puchunying@126.com [College of Physics and Electronic Engineering, Nanyang Normal University, Nanyang 473061 (China)

2015-11-05

Using the particle swarm optimization algorithm combined with first-principles methods, we explore the diagram of AlY alloy up to 250 GPa. It is found that AlDy phase, rather than the experimentally observed B2 phase, is the most stable structure at 0 K and 0–20 GPa. However, our results show that B2 phase can exist as a stable phase at 20–27.6 GPa. At higher pressure, four new high-pressure phases with Cmcm-I, Cmcm-II, I4/mmm and P4/nmm structure are identified for the first time. The hardness, elastic and thermodynamic properties of the newly found phases are investigated and compared with B2 phase. The calculated hardness of AlDy, Cmcm-I, Cmcm-II, I4/mmm and P4/nmm phases is in the range of 7–9 GPa, higher than that of B2 phase. In addition, it is found that AlDy phase is a brittle material at 0 GPa, which changes to a ductile material above 12 GPa. Except for AlDy phase, all the other AlY compounds exhibit completely ductile behavior under pressure. Compared with the other phases, B2 phase is found to have the best ductility and the largest elastic anisotropy over the whole pressure investigated. Moreover, all AlY intermetallics exhibit a nearly elastic isotropy in compressibility but a comparatively large elastic anisotropy in shear. The structural stability, electronic structure, bulk and shear modulus, Debye temperature as well as sound velocities of AlY alloy under pressure are also deeply discussed. - Graphical abstract: Pressure-induced phase transition of AlY alloy up to 250 GPa. - Highlights: • The diagram of AlY alloy was explored and four new stable phases were predicted. • B2 phase shows the largest ductility and elastic anisotropy among AlY alloys. • All AlY alloys exhibit ductile behavior except for AlDy phase under pressure. • All AlY alloys show strong isotropy in compressibility and anisotropy in shear.

Thermodynamic modeling and kinetics simulation of precipitate phases in AISI 316 stainless steels

International Nuclear Information System (INIS)

Yang, Y.; Busby, J.T.

2014-01-01

This work aims at utilizing modern computational microstructural modeling tools to accelerate the understanding of phase stability in austenitic steels under extended thermal aging. Using the CALPHAD approach, a thermodynamic database OCTANT (ORNL Computational Thermodynamics for Applied Nuclear Technology), including elements of Fe, C, Cr, Ni, Mn, Mo, Si, and Ti, has been developed with a focus on reliable thermodynamic modeling of precipitate phases in AISI 316 austenitic stainless steels. The thermodynamic database was validated by comparing the calculated results with experimental data from commercial 316 austenitic steels. The developed computational thermodynamics was then coupled with precipitation kinetics simulation to understand the temporal evolution of precipitates in austenitic steels under long-term thermal aging (up to 600,000 h) at a temperature regime from 300 to 900 °C. This study discusses the effect of dislocation density and difusion coefficients on the precipitation kinetics at low temperatures, which shed a light on investigating the phase stability and transformation in austenitic steels used in light water reactors

New methods of thermodynamics; Nouvelles methodes en thermodynamique

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-07-01

This day, organized by the SFT French Society of Thermology, took stock on the new methods in the domain of the thermodynamics. Eight papers have been presented during this day: new developments of the thermodynamics in finite time; the optimal efficiency of energy converters; a version of non-equilibrium thermodynamics with entropy and information as positive and negative thermal change; the role of thermodynamics in process integration; application of the thermodynamics to critical nuclear accidents; the entropic analysis help in the case of charge and discharge state of an energy storage process; fluid flow threw a stable state in the urban hydraulic; a computer code for phase diagram prediction. (A.L.B.)

Crystal-liquid-gas phase transitions and thermodynamic similarity

CERN Document Server

Skripov, Vladimir P; Schmelzer, Jurn W P

2006-01-01

Professor Skripov obtained worldwide recognition with his monograph ""Metastable liquids"", published in English by Wiley & Sons. Based upon this work and another monograph published only in Russia, this book investigates the behavior of melting line and the properties of the coexisting crystal and liquid phase of simple substances across a wide range of pressures, including metastable states of the coexisting phases. The authors derive new relations for the thermodynamic similarity for liquid-vapour phase transition, as well as describing solid-liquid, liquid-vapor and liquid-liquid phase tra

Application of non-equilibrium thermodynamics to two-phase flows with a change of phase

International Nuclear Information System (INIS)

Delhaye, J.M.

1969-01-01

In this report we use the methods of non-equilibrium thermodynamics in two-phase flows. This paper follows a prior one in which we have studied the conservation laws and derived the general equations of two-phase flow. In the first part the basic ideas of thermodynamics of irreversible systems are given. We follow the classical point of view. The second part is concerned with the derivation of a closed set of equations for the two phase elementary volume model. In this model we assume that the elementary volume contains two phases and that it is possible to define a volumetric local concentration. To obtain the entropy balance we can choose either the reversibility of the barycentric motion or the reversibility of each phase. We adopt the last assumption and our derivation is the same as this of I.Prigogine and P. Mazur about the hydrodynamics of liquid helium. The scope of this work is not to find a general solution to the problems of two phase flows but to obtain a new set of equations which may be used to explain some characteristic phenomena of two-phase flow such as wave propagation or critical states. (author) [fr

A statistical model for instable thermodynamical systems

International Nuclear Information System (INIS)

Sommer, Jens-Uwe

2003-01-01

A generic model is presented for statistical systems which display thermodynamic features in contrast to our everyday experience, such as infinite and negative heat capacities. Such system are instable in terms of classical equilibrium thermodynamics. Using our statistical model, we are able to investigate states of instable systems which are undefined in the framework of equilibrium thermodynamics. We show that a region of negative heat capacity in the adiabatic environment, leads to a first order like phase transition when the system is coupled to a heat reservoir. This phase transition takes place without a phase coexistence. Nevertheless, all intermediate states are stable due to fluctuations. When two instable system are brought in thermal contact, the temperature of the composed system is lower than the minimum temperature of the individual systems. Generally, the equilibrium states of instable system cannot be simply decomposed into equilibrium states of the individual systems. The properties of instable system depend on the environment, ensemble equivalence is broken

Phase transition and thermodynamic stability of topological black holes in Hořava-Lifshitz gravity

Science.gov (United States)

Ma, Meng-Sen; Zhao, Ren; Liu, Yan-Song

2017-08-01

On the basis of horizon thermodynamics, we study the thermodynamic stability and P-V criticality of topological black holes constructed in Hořava-Lifshitz (HL) gravity without the detailed-balance condition (with general ɛ). In the framework of horizon thermodynamics, we do not need the concrete black hole solution (the metric function) and the concrete matter fields. It is shown that the HL black hole for k=0 is always thermodynamically stable. For k=1 , the thermodynamic behaviors and P-V criticality of the HL black hole are similar to those of RN-AdS black hole for some \

Thermodynamics of Horndeski black holes with non-minimal derivative coupling

Energy Technology Data Exchange (ETDEWEB)

Miao, Yan-Gang [Nankai University, School of Physics, Tianjin (China); Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut), Potsdam (Germany); Xu, Zhen-Ming [Nankai University, School of Physics, Tianjin (China)

2016-11-15

We explore thermodynamic properties of a new class of Horndeski black holes whose action contains a non-minimal kinetic coupling of a massless real scalar and the Einstein tensor. Our treatment is based on the well-accepted consideration, where the cosmological constant is dealt with as thermodynamic pressure and the mass of black holes as thermodynamic enthalpy. We resort to a newly introduced intensive thermodynamic variable, i.e., the coupling strength of the scalar and tensor whose dimension is length square, and thus yield both the generalized first law of thermodynamics and the generalized Smarr relation. Our result indicates that this class of Horndeski black holes presents rich thermodynamic behaviors and critical phenomena. Especially in the case of the presence of an electric field, these black holes undergo two phase transitions. Once the charge parameter exceeds its critical value, or the cosmological parameter does not exceed its critical value, no phase transitions happen and the black holes are stable. As a by-product, we point out, the coupling strength acts as the thermodynamic pressure in thermodynamics. (orig.)

Thermodynamics of Horndeski black holes with non-minimal derivative coupling

International Nuclear Information System (INIS)

Miao, Yan-Gang; Xu, Zhen-Ming

2016-01-01

We explore thermodynamic properties of a new class of Horndeski black holes whose action contains a non-minimal kinetic coupling of a massless real scalar and the Einstein tensor. Our treatment is based on the well-accepted consideration, where the cosmological constant is dealt with as thermodynamic pressure and the mass of black holes as thermodynamic enthalpy. We resort to a newly introduced intensive thermodynamic variable, i.e., the coupling strength of the scalar and tensor whose dimension is length square, and thus yield both the generalized first law of thermodynamics and the generalized Smarr relation. Our result indicates that this class of Horndeski black holes presents rich thermodynamic behaviors and critical phenomena. Especially in the case of the presence of an electric field, these black holes undergo two phase transitions. Once the charge parameter exceeds its critical value, or the cosmological parameter does not exceed its critical value, no phase transitions happen and the black holes are stable. As a by-product, we point out, the coupling strength acts as the thermodynamic pressure in thermodynamics. (orig.)

Thermodynamic stability of modified Schwarzschild-AdS black hole in rainbow gravity

Energy Technology Data Exchange (ETDEWEB)

Kim, Yong-Wan [Chonbuk National University, Research Institute of Physics and Chemistry, Jeonju (Korea, Republic of); Kim, Seung Kook [Seonam University, Department of Physical Therapy, Namwon (Korea, Republic of); Park, Young-Jai [Sogang University, Department of Physics, Seoul (Korea, Republic of)

2016-10-15

In this paper, we have extended the previous study of the thermodynamics and phase transition of the Schwarzschild black hole in the rainbow gravity to the Schwarzschild-AdS black hole where metric depends on the energy of a probe. Making use of the Heisenberg uncertainty principle and the modified dispersion relation, we have obtained the modified local Hawking temperature and thermodynamic quantities in an isothermal cavity. Moreover, we carry out the analysis of constant temperature slices of a black hole. As a result, we have shown that there also exists another Hawking-Page-like phase transition in which case a locally stable small black hole tunnels into a globally stable large black hole as well as the standard Hawking-Page phase transition from a hot flat space to a black hole. (orig.)

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.

A Tractable Disequilbrium Framework for Integrating Computational Thermodynamics and Geodynamics

Science.gov (United States)

Spiegelman, M. W.; Tweed, L. E. L.; Evans, O.; Kelemen, P. B.; Wilson, C. R.

2017-12-01

The consistent integration of computational thermodynamics and geodynamics is essential for exploring and understanding a wide range of processes from high-PT magma dynamics in the convecting mantle to low-PT reactive alteration of the brittle crust. Nevertheless, considerable challenges remain for coupling thermodynamics and fluid-solid mechanics within computationally tractable and insightful models. Here we report on a new effort, part of the ENKI project, that provides a roadmap for developing flexible geodynamic models of varying complexity that are thermodynamically consistent with established thermodynamic models. The basic theory is derived from the disequilibrium thermodynamics of De Groot and Mazur (1984), similar to Rudge et. al (2011, GJI), but extends that theory to include more general rheologies, multiple solid (and liquid) phases and explicit chemical reactions to describe interphase exchange. Specifying stoichiometric reactions clearly defines the compositions of reactants and products and allows the affinity of each reaction (A = -Δ/Gr) to be used as a scalar measure of disequilibrium. This approach only requires thermodynamic models to return chemical potentials of all components and phases (as well as thermodynamic quantities for each phase e.g. densities, heat capacity, entropies), but is not constrained to be in thermodynamic equilibrium. Allowing meta-stable phases mitigates some of the computational issues involved with the introduction and exhaustion of phases. Nevertheless, for closed systems, these problems are guaranteed to evolve to the same equilibria predicted by equilibrium thermodynamics. Here we illustrate the behavior of this theory for a range of simple problems (constructed with our open-source model builder TerraFERMA) that model poro-viscous behavior in the well understood Fo-Fa binary phase loop. Other contributions in this session will explore a range of models with more petrologically interesting phase diagrams as well as

A Global Survey of Cloud Thermodynamic Phase using High Spatial Resolution VSWIR Spectroscopy, 2005-2015

Science.gov (United States)

Thompson, D. R.; Kahn, B. H.; Green, R. O.; Chien, S.; Middleton, E.; Tran, D. Q.

2017-12-01

Clouds' variable ice and liquid content significantly influences their optical properties, evolution, and radiative forcing potential (Tan and Storelvmo, J. Atmos. Sci, 73, 2016). However, most remote measurements of thermodynamic phase have spatial resolutions of 1 km or more and are insensitive to mixed phases. This under-constrains important processes, such as spatial partitioning within mixed phase clouds, that carry outsize radiative forcing impacts. These uncertainties could shift Global Climate Model (GCM) predictions of future warming by over 1 degree Celsius (Tan et al., Science 352:6282, 2016). Imaging spectroscopy of reflected solar energy from the 1.4 - 1.8 μm shortwave infrared (SWIR) spectral range can address this observational gap. These observations can distinguish ice and water absorption, providing a robust and sensitive measurement of cloud top thermodynamic phase including mixed phases. Imaging spectrometers can resolve variations at scales of tens to hundreds of meters (Thompson et al., JGR-Atmospheres 121, 2016). We report the first such global high spatial resolution (30 m) survey, based on data from 2005-2015 acquired by the Hyperion imaging spectrometer onboard NASA's EO-1 spacecraft (Pearlman et al., Proc. SPIE 4135, 2001). Estimated seasonal and latitudinal distributions of cloud thermodynamic phase generally agree with observations made by other satellites such as the Atmospheric Infrared Sounder (AIRS). Variogram analyses reveal variability at different spatial scales. Our results corroborate previously observed zonal distributions, while adding insight into the spatial scales of processes governing cloud top thermodynamic phase. Figure: Thermodynamic phase retrievals. Top: Example of a cloud top thermodynamic phase map from the EO-1/Hyperion. Bottom: Latitudinal distributions of pure and mixed phase clouds, 2005-2015, showing Liquid Thickness Fraction (LTF). LTF=0 corresponds to pure ice absorption, while LTF=1 is pure liquid. The

Thermodynamics of Crystalline States

CERN Document Server

Fujimoto, Minoru

2013-01-01

Thermodynamics is a well-established discipline of physics for properties of matter in thermal equilibrium with the surroundings. Applying to crystals, however, the laws encounter undefined properties of crystal lattice, which therefore need to be determined for a clear and well-defined description of crystalline states. Thermodynamics of Crystalline States explores the roles played by order variables and dynamic lattices in crystals in a wholly new way. The book begins by clarifying basic concepts for stable crystals. Next, binary phase transitions are discussed to study collective motion of order variables, as described mostly as classical phenomena. New to this edition is the examination of magnetic crystals, where magnetic symmetry is essential for magnetic phase transitions. The multi-electron system is also discussed  theoretically, as a quantum-mechanical example, for superconductivity in metallic crystals. Throughout the book, the role played by the lattice is emphasized and studied in-depth. Thermod...

Thermodynamic modeling of mineralogical phases formed by continuous casting powders

International Nuclear Information System (INIS)

Romo-Castaneda, Julio; Cruz-Ramirez, Alejandro; Romero-Serrano, Antonio; Vargas-Ramirez, Marissa; Hallen-Lopez, Manuel

2011-01-01

A great amount of mineralogical phases were predicted and represented in stability phase diagrams, which were obtained by the use of the thermodynamic software FACTSage considering both the chemical composition and the melting temperature of the mould flux. Melting-solidification tests on commercial mould flux glasses for thin slab casting of steel revealed the existence of cuspidine (Ca 4 Si 2 O 7 F 2 ) as the main mineralogical phase formed during the flux solidification by X-ray powder diffraction (XRD). This phase directly influences the heat transfer phenomena from the strand to the mould and it is obtained with higher fluorite content (22% CaF 2 ). Cuspidine is desirable only in fluxes to produce medium carbon (included peritectic grade) steels, because it reduces the heat flux from the strand to the mould, thus controlling the shrinkage rate during the flux solidification. The experimental results are in agreement with those obtained by the thermodynamic software. The stability phase diagrams could be used as an important tool in the flux design for continuous casting process.

Thermodynamic modeling of mineralogical phases formed by continuous casting powders

Energy Technology Data Exchange (ETDEWEB)

Romo-Castaneda, Julio [Metallurgy and Materials Department, Instituto Politecnico Nacional-ESIQIE, Apdo. P. 118-431, 07051 Mexico D.F. (Mexico); Cruz-Ramirez, Alejandro, E-mail: alcruzr@ipn.mx [Metallurgy and Materials Department, Instituto Politecnico Nacional-ESIQIE, Apdo. P. 118-431, 07051 Mexico D.F. (Mexico); Romero-Serrano, Antonio; Vargas-Ramirez, Marissa; Hallen-Lopez, Manuel [Metallurgy and Materials Department, Instituto Politecnico Nacional-ESIQIE, Apdo. P. 118-431, 07051 Mexico D.F. (Mexico)

2011-01-10

A great amount of mineralogical phases were predicted and represented in stability phase diagrams, which were obtained by the use of the thermodynamic software FACTSage considering both the chemical composition and the melting temperature of the mould flux. Melting-solidification tests on commercial mould flux glasses for thin slab casting of steel revealed the existence of cuspidine (Ca{sub 4}Si{sub 2}O{sub 7}F{sub 2}) as the main mineralogical phase formed during the flux solidification by X-ray powder diffraction (XRD). This phase directly influences the heat transfer phenomena from the strand to the mould and it is obtained with higher fluorite content (22% CaF{sub 2}). Cuspidine is desirable only in fluxes to produce medium carbon (included peritectic grade) steels, because it reduces the heat flux from the strand to the mould, thus controlling the shrinkage rate during the flux solidification. The experimental results are in agreement with those obtained by the thermodynamic software. The stability phase diagrams could be used as an important tool in the flux design for continuous casting process.

Thermodynamic analysis of the two-phase ejector air-conditioning system for buses

International Nuclear Information System (INIS)

Ünal, Şaban; Yilmaz, Tuncay

2015-01-01

Air-conditioning compressors of the buses are usually operated with the power taken from the engine of the buses. Therefore, an improvement in the air-conditioning system will reduce the fuel consumption of the buses. The improvement in the coefficient of performance (COP) of the air-conditioning system can be provided by using the two-phase ejector as an expansion valve in the air-conditioning system. In this study, the thermodynamic analysis of bus air-conditioning system enhanced with a two-phase ejector and two evaporators is performed. Thermodynamic analysis is made assuming that the mixing process in ejector occurs at constant cross-sectional area and constant pressure. The increase rate in the COP with respect to conventional system is analyzed in terms of the subcooling, condenser and evaporator temperatures. The analysis shows that COP improvement of the system by using the two phase ejector as an expansion device is 15% depending on design parameters of the existing bus air-conditioning system. - Highlights: • Thermodynamic analysis of the two-phase ejector refrigeration system. • Analysis of the COP increase rate of bus air-conditioning system. • Analysis of the entrainment ratio of the two-phase ejector refrigeration system

Applications of thermodynamic calculations to Mg alloy design: Mg-Sn based alloy development

International Nuclear Information System (INIS)

Jung, In-Ho; Park, Woo-Jin; Ahn, Sang Ho; Kang, Dae Hoon; Kim, Nack J.

2007-01-01

Recently an Mg-Sn based alloy system has been investigated actively in order to develop new magnesium alloys which have a stable structure and good mechanical properties at high temperatures. Thermodynamic modeling of the Mg-Al-Mn-Sb-Si-Sn-Zn system was performed based on available thermodynamic, phase equilibria and phase diagram data. Using the optimized database, the phase relationships of the Mg-Sn-Al-Zn alloys with additions of Si and Sb were calculated and compared with their experimental microstructures. It is shown that the calculated results are in good agreement with experimental microstructures, which proves the applicability of thermodynamic calculations for new Mg alloy design. All calculations were performed using FactSage thermochemical software. (orig.)

Split degenerate states and stable p+ip phases from holography

Energy Technology Data Exchange (ETDEWEB)

Nie, Zhang-Yu; Zeng, Hui [Kunming University of Science and Technology, Kunming (China); Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing (China); Pan, Qiyuan [Hunan Normal Univ., Key Lab. of Low Dimensional Quantum Structures and Quantum Control of Ministry of Education, and Synergetic Innovation Center for Quantum Effects and Applications, Dept. of Physics, Changsha (China); Zeng, Hua-Bi [Yangzhou University, College of Physics Science and Technology, Yangzhou, Jiangsu (China); National Central University, Department of Physics, Chungli (China)

2017-02-15

In this paper, we investigate the p+ip superfluid phases in the complex vector field holographic p-wave model. We find that in the probe limit, the p+ip phase and the p-wave phase are equally stable, hence the p and ip orders can be mixed with an arbitrary ratio to form more general p+λip phases, which are also equally stable with the p-wave and p+ip phases. As a result, the system possesses a degenerate thermal state in the superfluid region. We further study the case on considering the back-reaction on the metric, and we find that the degenerate ground states will be separated into p-wave and p+ip phases, and the p-wave phase is more stable. Finally, due to the different critical temperature of the zeroth order phase transitions from p-wave and p+ip phases to the normal phase, there is a temperature region where the p+ip phase exists but the p-wave phase does not. In this region we find the stable holographic p+ip phase for the first time. (orig.)

Thermodynamics of Crystalline States

CERN Document Server

Fujimoto, Minoru

2010-01-01

Thermodynamics is a well-established discipline of physics for properties of matter in thermal equilibrium surroundings. Applying to crystals, however, the laws encounter undefined properties of crystal lattices, which therefore need to be determined for a clear and well-defined description of crystalline states. Thermodynamics of Crystalline States explores the roles played by order variables and dynamic lattices in crystals in a wholly new way. This book is divided into three parts. The book begins by clarifying basic concepts for stable crystals. Next, binary phase transitions are discussed to study collective motion of order variables, as described mostly as classical phenomena. In the third part, the multi-electron system is discussed theoretically, as a quantum-mechanical example, for the superconducting state in metallic crystals. Throughout the book, the role played by the lattice is emphasized and examined in-depth. Thermodynamics of Crystalline States is an introductory treatise and textbook on meso...

Thermodynamic study of CVD-ZrO{sub 2} phase diagrams

Energy Technology Data Exchange (ETDEWEB)

Torres-Huerta, A.M., E-mail: atorresh@ipn.m [Research Center for Applied Science and Advanced Technology, Altamira-IPN, Altamira C.P.89600 Tamaulipas (Mexico); Vargas-Garcia, J.R. [Dept of Metallurgical Eng., ESIQIE-IPN, Mexico 07300 D.F. (Mexico); Dominguez-Crespo, M.A. [Research Center for Applied Science and Advanced Technology, Altamira-IPN, Altamira C.P.89600 Tamaulipas (Mexico); Romero-Serrano, J.A. [Dept of Metallurgical Eng., ESIQIE-IPN, Mexico 07300 D.F. (Mexico)

2009-08-26

Chemical vapor deposition (CVD) of zirconium oxide (ZrO{sub 2}) from zirconium acetylacetonate Zr(acac){sub 4} has been thermodynamically investigated using the Gibbs' free energy minimization method and the FACTSAGE program. Thermodynamic data Cp{sup o}, DELTAH{sup o} and S{sup o} for Zr(acac){sub 4} have been estimated using the Meghreblian-Crawford-Parr and Benson methods because they are not available in the literature. The effect of deposition parameters, such as temperature and pressure, on the extension of the region where pure ZrO{sub 2} can be deposited was analyzed. The results are presented as calculated CVD stability diagrams. The phase diagrams showed two zones, one of them corresponds to pure monoclinic phase of ZrO{sub 2} and the other one corresponds to a mix of monoclinic phase of ZrO{sub 2} and graphite carbon.

Phase transformations and thermodynamics of aluminum-based metallic glasses

Science.gov (United States)

Gao, Changhua (Michael)

This thesis examines the thermodynamics and associated kinetics and phase transformations of the glass forming Al-Ni-Gd and Al-Fe-Gd systems. In order to fully understand the unique glass forming ability (GFA) of Al-based metallic glasses, the ternary Al-Fe-Gd and Al-Ni-Gd systems in their Al-rich corners were examined experimentally to assist in a thermodynamic assessment. The solid-state phase equilibria are determined using XRD and TEM-EDS techniques. While this work basically confirms the solid-state equilibria in Al-Fe-Gd reported previously, the ternary phase in Al-Ni-Gd system has been identified to be Al15Ni3Gd2 rather than Al16Ni 3Gd reported in the literature. DTA analysis of 24 alloys in the Al-Fe-Gd system and 42 alloys in the Al-Ni-Gd system have yielded critical temperatures pertaining to the solid-liquid transition. Based on these data and information from the literature, a self-consistent thermodynamic database for these systems has been developed using the CALPHAD technique. Parameters describing the Gibbs free energy for various phases of the Al-Gd, Al-Fe-Gd and Al-Ni-Gd systems are manually optimized in this study. Once constructed, the database is used to calculate driving forces for nucleation of crystalline phases which can qualitatively explain the phase formation sequence during crystallization at low temperatures. It was also confirmed that alloy compositions with the lowest Gibbs free energy difference between the equilibrium state and undercooled liquid state exhibit better GFA than other chemistries. Based on 250°C isothermal devitrification phase transformations of 17 Al-Ni-Gd alloys, a phase formation sequence map is constructed. Fcc-Al nanocrystals are formed first in most of the alloys studied, but eutectic crystallization of a metastable phase and fcc-Al is also observed. Addition of Al or Ni promotes fcc-Al phase formation, while increasing Gd suppresses it. The continuous heating DSC scans revealed that crystallization in Al

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

Thermodynamic aspects of grain refinement of Al-Si alloys using Ti and B

Energy Technology Data Exchange (ETDEWEB)

Groebner, Joachim [Technical University of Clausthal, Institute of Metallurgy, Robert-Koch-Str. 42, D-38678 Clausthal-Zellerfeld (Germany); Mirkovic, Djordje [Technical University of Clausthal, Institute of Metallurgy, Robert-Koch-Str. 42, D-38678 Clausthal-Zellerfeld (Germany); Schmid-Fetzer, Rainer [Technical University of Clausthal, Institute of Metallurgy, Robert-Koch-Str. 42, D-38678 Clausthal-Zellerfeld (Germany)]. E-mail: schmid-fetzer@tu-clausthal.de

2005-03-25

A thermodynamic assessment of ternary Al-Si-Ti phases was performed. Published datasets for the other subsystems were checked and adapted. Based on that, a consistent thermodynamic description of quaternary Al-Si-Ti-B alloys was generated. This was applied in a calculation of Al-Si-Ti-B phase diagram sections for practically relevant temperatures and compositions of Al-Si alloys from Al-rich to typical Al-Si foundry alloys. These stable and metastable phase diagrams could be correlated to many detailed aspects of possible reactions observed or suggested in experimental studies of grain refining. Understanding the mechanisms of grain refining of Al wrought alloys and Al-Si foundry alloys using titanium and boron requires a fundamental knowledge of both thermodynamic and kinetic aspects of this complex process. This work focuses exclusively on the thermodynamic aspects and the phase diagrams, which were not available for the quaternary alloys and partly incomplete and inconsistent for the ternary subsystems.

A re-examination of thermodynamic modelling of U-Ru binary phase diagram

Energy Technology Data Exchange (ETDEWEB)

Wang, L.C.; Kaye, M.H., E-mail: matthew.kaye@uoit.ca [University of Ontario Institute of Technology, Oshawa, ON (Canada)

2015-07-01

Ruthenium (Ru) is one of the more abundant fission products (FPs) both in fast breeder reactors and thermal reactors. Post irradiation examinations (PIE) show that both 'the white metallic phase' (MoTc-Ru-Rh-Pd) and 'the other metallic phase' (U(Pd-Rh-Ru)3) are present in spent nuclear fuels. To describe this quaternary system, binary subsystems of uranium (U) with Pd, Rh, and Ru are necessary. Presently, only the U-Ru system has been thermodynamically described but with some problems. As part of research on U-Ru-Rh-Pd quaternary system, an improved consistent thermodynamic model describing the U-Ru binary phase diagram has been obtained. (author)

Surface thermodynamics

International Nuclear Information System (INIS)

Garcia-Moliner, F.

1975-01-01

Basic thermodynamics of a system consisting of two bulk phases with an interface. Solid surfaces: general. Discussion of experimental data on surface tension and related concepts. Adsorption thermodynamics in the Gibbsian scheme. Adsorption on inert solid adsorbents. Systems with electrical charges: chemistry and thermodynamics of imperfect crystals. Thermodynamics of charged surfaces. Simple models of charge transfer chemisorption. Adsorption heat and related concepts. Surface phase transitions

Assessment of the thermodynamic properties and phase diagram of the Bi–Pd system

Czech Academy of Sciences Publication Activity Database

Vřešťál, J.; Pinkas, J.; Watson, A.; Scott, A.; Houserová, Jana; Kroupa, Aleš

2006-01-01

Roč. 30, č. 1 (2006), s. 14-17 ISSN 0364-5916 R&D Projects: GA MŠk(CZ) OC 531.002 Institutional research plan: CEZ:AV0Z2041904 Keywords : phase diagram * thermodynamic modelling Subject RIV: BJ - Thermodynamics Impact factor: 1.432, year: 2006

On Thermodynamics Problems in the Single-Phase-Lagging Heat Conduction Model

Directory of Open Access Journals (Sweden)

Shu-Nan Li

2016-11-01

Full Text Available Thermodynamics problems for the single-phase-lagging (SPL model have not been much studied. In this paper, the violation of the second law of thermodynamics by the SPL model is studied from two perspectives, which are the negative entropy production rate and breaking equilibrium spontaneously. The methods for the SPL model to avoid the negative entropy production rate are proposed, which are extended irreversible thermodynamics and the thermal relaxation time. Modifying the entropy production rate positive or zero is not enough to avoid the violation of the second law of thermodynamics for the SPL model, because the SPL model could cause breaking equilibrium spontaneously in some special circumstances. As comparison, it is shown that Fourier’s law and the CV model cannot break equilibrium spontaneously by analyzing mathematical energy integral.

Thermodynamics and phase diagrams of the plutonium-uranium, uranium-zirconium, plutonium-zirconium and plutonium-uranium-zirconium systems

International Nuclear Information System (INIS)

Agarwal, R.; Venugopal, V.

2004-05-01

Thermodynamic and phase diagram data reported in literature for the binaries, Pu-U, Pu-Zr and U-Zr , were compiled and optimised to calculate Gibbs energies of all the binary phases of these systems. Lukas program was used to carry out these optimisations, where, thermodynamic and phase diagram data of all the binary phases of a binary system were optimised simultaneously. Gibbs energy sets thus calculated were used to compare our results with the experimental and calculated phase diagram and thermodynamic data reponed in the literature. The Gibbs energies of the binary systems were then compiled together to define Pu-U-Zr ternary system. (author)

Formation of co-crystals: Kinetic and thermodynamic aspects

Science.gov (United States)

Gagnière, E.; Mangin, D.; Puel, F.; Rivoire, A.; Monnier, O.; Garcia, E.; Klein, J. P.

2009-04-01

Co-crystallisation is a recent method of great interest for the pharmaceutical industry, since pharmaceutical co-crystals represent useful materials for drug products. In this study, an active pharmaceutical ingredient (carbamazepine (CBZ)) co-crystallized with a vitamin (nicotinamide (NCT)) was chosen as a model substance. This work was focused on the construction of a phase diagram for the system CBZ/NCT, split in six domains for kinetic reasons (the different solid phases which might appear during the crystallisation) and in four domains according to thermodynamic aspects (the stable final phase obtained). Although co-crystals are not ionic compounds, the supersaturation of co-crystals can be evaluated by considering the solubility product. Batch crystallisation operations were carried out in a stirred vessel equipped with an in situ video probe. This latter device was a powerful analysis tool to monitor the CBZ/NCT co-crystals and single CBZ crystals since these two crystalline phases grown in ethanol exhibited needle and platelet habits. As concerns kinetics, the different solid phases which might appear during the experiments were observed and competed against each others. In accordance with thermodynamics, the stable solid form was obtained at the end of the operation. Finally some preliminary results indicate that the nucleation of co-crystals may be favoured by the presence of CBZ crystals. Epitaxial relationships between CBZ/NCT co-crystals and CBZ crystals were suspected.

Optimization of the thermodynamic properties and phase diagrams of P2O5-containing systems

Science.gov (United States)

Hudon, Pierre; Jung, In-Ho

2014-05-01

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

Thermodynamic modeling of hydrogen storage capacity in Mg-Na alloys.

Science.gov (United States)

Abdessameud, S; Mezbahul-Islam, M; Medraj, M

2014-01-01

Thermodynamic modeling of the H-Mg-Na system is performed for the first time in this work in order to understand the phase relationships in this system. A new thermodynamic description of the stable NaMgH3 hydride is performed and the thermodynamic models for the H-Mg, Mg-Na, and H-Na systems are reassessed using the modified quasichemical model for the liquid phase. The thermodynamic properties of the ternary system are estimated from the models of the binary systems and the ternary compound using CALPHAD technique. The constructed database is successfully used to reproduce the pressure-composition isotherms for MgH2 + 10 wt.% NaH mixtures. Also, the pressure-temperature equilibrium diagram and reaction paths for the same composition are predicted at different temperatures and pressures. Even though it is proved that H-Mg-Na does not meet the DOE hydrogen storage requirements for onboard applications, the best working temperatures and pressures to benefit from its full catalytic role are given. Also, the present database can be used for thermodynamic assessments of higher order systems.

Thermodynamically consistent simulation of nonisothermal diffuse-interface two-phase flow with Peng-Robinson equation of state

KAUST Repository

Kou, Jisheng; Sun, Shuyu

2017-01-01

In this paper, we consider a diffuse-interface gas-liquid two-phase flow model with inhomogeneous temperatures, in which we employ the Peng-Robinson equation of state and the temperature-dependent influence parameter instead of the van der Waals equation of state and the constant influence parameter used in the existing models. As a result, our model can characterize accurately the physical behaviors of numerous realistic gas-liquid fluids, especially hydrocarbons. Furthermore, we prove a relation associating the pressure gradient with the gradients of temperature and chemical potential, and thereby derive a new formulation of the momentum balance equation, which shows that gradients of the chemical potential and temperature become the primary driving force of the fluid motion. It is rigorously proved that the new formulations of the model obey the first and second laws of thermodynamics. To design efficient numerical methods, we prove that Helmholtz free energy density is a concave function with respect to the temperature under certain physical conditions. Based on the proposed modeling formulations and the convex-concave splitting of Helmholtz free energy density, we propose a novel thermodynamically stable numerical scheme. We rigorously prove that the proposed method satisfies the first and second laws of thermodynamics. Finally, numerical tests are carried out to verify the effectiveness of the proposed simulation method.

Thermodynamically consistent simulation of nonisothermal diffuse-interface two-phase flow with Peng-Robinson equation of state

KAUST Repository

Kou, Jisheng

2017-12-06

In this paper, we consider a diffuse-interface gas-liquid two-phase flow model with inhomogeneous temperatures, in which we employ the Peng-Robinson equation of state and the temperature-dependent influence parameter instead of the van der Waals equation of state and the constant influence parameter used in the existing models. As a result, our model can characterize accurately the physical behaviors of numerous realistic gas-liquid fluids, especially hydrocarbons. Furthermore, we prove a relation associating the pressure gradient with the gradients of temperature and chemical potential, and thereby derive a new formulation of the momentum balance equation, which shows that gradients of the chemical potential and temperature become the primary driving force of the fluid motion. It is rigorously proved that the new formulations of the model obey the first and second laws of thermodynamics. To design efficient numerical methods, we prove that Helmholtz free energy density is a concave function with respect to the temperature under certain physical conditions. Based on the proposed modeling formulations and the convex-concave splitting of Helmholtz free energy density, we propose a novel thermodynamically stable numerical scheme. We rigorously prove that the proposed method satisfies the first and second laws of thermodynamics. Finally, numerical tests are carried out to verify the effectiveness of the proposed simulation method.

Thermodynamics and phases in quantum gravity

International Nuclear Information System (INIS)

Husain, Viqar; Mann, R B

2009-01-01

We give an approach for studying quantum gravity effects on black hole thermodynamics. This combines a quantum framework for gravitational collapse with quasi-local definitions of energy and surface gravity. Our arguments suggest that (i) the specific heat of a black hole becomes positive after a phase transition near the Planck scale,(ii) its entropy acquires a logarithmic correction and (iii) the mass loss rate is modified such that Hawking radiation stops near the Planck scale. These results are due essentially to a realization of fundamental discreteness in quantum gravity, and are in this sense potentially theory independent.

Stability and fluctuations in black hole thermodynamics

International Nuclear Information System (INIS)

Ruppeiner, George

2007-01-01

I examine thermodynamic fluctuations for a Kerr-Newman black hole in an extensive, infinite environment. This problem is not strictly solvable because full equilibrium with such an environment cannot be achieved by any black hole with mass M, angular momentum J, and charge Q. However, if we consider one (or two) of M, J, or Q to vary so slowly compared with the others that we can regard it as fixed, instances of stability occur, and thermodynamic fluctuation theory could plausibly apply. I examine seven cases with one, two, or three independent fluctuating variables. No knowledge about the thermodynamic behavior of the environment is needed. The thermodynamics of the black hole is sufficient. Let the fluctuation moment for a thermodynamic quantity X be √( 2 >). Fluctuations at fixed M are stable for all thermodynamic states, including that of a nonrotating and uncharged environment, corresponding to average values J=Q=0. Here, the fluctuation moments for J and Q take on maximum values. That for J is proportional to M. For the Planck mass it is 0.3990(ℎ/2π). That for Q is 3.301e, independent of M. In all cases, fluctuation moments for M, J, and Q go to zero at the limit of the physical regime, where the temperature goes to zero. With M fluctuating there are no stable cases for average J=Q=0. But, there are transitions to stability marked by infinite fluctuations. For purely M fluctuations, this coincides with a curve which Davies identified as a phase transition

Thermodynamic geometry and phase transitions of dyonic charged AdS black holes

Energy Technology Data Exchange (ETDEWEB)

Chaturvedi, Pankaj; Sengupta, Gautam [Indian Institute of Technology Kanpur, Department of Physics, Kanpur (India); Das, Anirban [Tata Institute of Fundamental Research, Department of Theoretical Physics, Mumbai (India)

2017-02-15

We investigate phase transitions and critical phenomena of four dimensional dyonic charged AdS black holes in the framework of thermodynamic geometry. In a mixed canonical-grand canonical ensemble with a fixed electric charge and varying magnetic charge these black holes exhibit a liquid-gas like first order phase transition culminating in a second order critical point similar to the van der Waals gas. We show that the thermodynamic scalar curvature R for these black holes follow our proposed geometrical characterization of the R-crossing Method for the first order liquid-gas like phase transition and exhibits a divergence at the second order critical point. The pattern of R crossing and divergence exactly corresponds to those of a van der Waals gas described by us in an earlier work. (orig.)

Thermodynamics phase changes of nanopore fluids

KAUST Repository

Islam, Akand W.

2015-07-01

The van der Waals (vdW) equation (Eq.) is modified to describe thermodynamic of phase behavior of fluids confined in nanopore. Our aim is to compute pressures exerted by the fluid molecules and to investigate how they change due to pore proximity by assuming the pore wall is inert. No additional scaling of model parameters is imposed and original volume and energy parameters are used in the calculations. Our results clearly show the phase changes due to confinement. The critical shifts of temperatures and pressures are in good agreement compared to the laboratory data and molecular simulation. Peng-Robinson (PR) equation-of-state (EOS) has resulted in different effect than the vdW. This work delivers insights into the nature of fluid behavior in extremely low-permeability nanoporous media, especially in the tight shale reservoirs, below the critical temperatures. © 2015 Elsevier B.V.

Thermodynamics phase changes of nanopore fluids

KAUST Repository

Islam, Akand W.; Patzek, Tadeusz; Sun, Alexander Y.

2015-01-01

The van der Waals (vdW) equation (Eq.) is modified to describe thermodynamic of phase behavior of fluids confined in nanopore. Our aim is to compute pressures exerted by the fluid molecules and to investigate how they change due to pore proximity by assuming the pore wall is inert. No additional scaling of model parameters is imposed and original volume and energy parameters are used in the calculations. Our results clearly show the phase changes due to confinement. The critical shifts of temperatures and pressures are in good agreement compared to the laboratory data and molecular simulation. Peng-Robinson (PR) equation-of-state (EOS) has resulted in different effect than the vdW. This work delivers insights into the nature of fluid behavior in extremely low-permeability nanoporous media, especially in the tight shale reservoirs, below the critical temperatures. © 2015 Elsevier B.V.

Method of non-interacting thermodynamic calculation of binary phase diagrams containing p disordered phases with variable composition and q phases with constant composition at (p, q) ≤ 10

International Nuclear Information System (INIS)

Udovskij, A.L.; Karpushkin, V.N.; Nikishina, E.A.

1991-01-01

Method of non-interacting thermodynamic calculation of state diagram of binary systems contacting p disordered phases with variable composition and q phases with constant composition for (p, q) ≤ 10 case is developed. Determination of all possible solutions of phase equilibrium equations is realized in the method. Certain application examples of computer-realized method of T-x thermodynamic calculation using PC for Cr-W, Ni-W, Ni-Al, Ni-Re binary systems are given

Thermodynamic Calculations of Ternary Polyalcohol and Amine Phase Diagrams for Thermal Energy Storage Materials

Science.gov (United States)

Shi, Renhai

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

Thermodynamics of Born-Infeld-anti-de Sitter black holes in the grand canonical ensemble

International Nuclear Information System (INIS)

Fernando, Sharmanthie

2006-01-01

The main objective of this paper is to study thermodynamics and stability of static electrically charged Born-Infeld black holes in AdS space in D=4. The Euclidean action for the grand canonical ensemble is computed with the appropriate boundary terms. The thermodynamical quantities such as the Gibbs free energy, entropy and specific heat of the black holes are derived from it. The global stability of black holes are studied in detail by studying the free energy for various potentials. For small values of the potential, we find that there is a Hawking-Page phase transition between a BIAdS black hole and the thermal-AdS space. For large potentials, the black hole phase is dominant and is preferred over the thermal-AdS space. Local stability is studied by computing the specific heat for constant potentials. The nonextreme black holes have two branches: small black holes are unstable and the large black holes are stable. The extreme black holes are shown to be stable both globally as well as locally. In addition to the thermodynamics, we also show that the phase structure relating the mass M and the charge Q of the black holes is similar to the liquid-gas-solid phase diagram

Correlation between thermodynamic anomalies and pathways of ice nucleation in supercooled water

International Nuclear Information System (INIS)

Singh, Rakesh S.; Bagchi, Biman

2014-01-01

The well-known classical nucleation theory (CNT) for the free energy barrier towards formation of a nucleus of critical size of the new stable phase within the parent metastable phase fails to take into account the influence of other metastable phases having density/order intermediate between the parent metastable phase and the final stable phase. This lacuna can be more serious than capillary approximation or spherical shape assumption made in CNT. This issue is particularly significant in ice nucleation because liquid water shows rich phase diagram consisting of two (high and low density) liquid phases in supercooled state. The explanations of thermodynamic and dynamic anomalies of supercooled water often invoke the possible influence of a liquid-liquid transition between two metastable liquid phases. To investigate both the role of thermodynamic anomalies and presence of distinct metastable liquid phases in supercooled water on ice nucleation, we employ density functional theoretical approach to find nucleation free energy barrier in different regions of phase diagram. The theory makes a number of striking predictions, such as a dramatic lowering of nucleation barrier due to presence of a metastable intermediate phase and crossover in the dependence of free energy barrier on temperature near liquid-liquid critical point. These predictions can be tested by computer simulations as well as by controlled experiments

Comparison of the thermodynamic properties and high temperature chemical behavior of lanthanide and actinide oxides

International Nuclear Information System (INIS)

Ackermann, R.J.; Rauh, E.G.

1977-01-01

The thermodynamic properties of the lanthanide and actinide oxides are examined, compared, and associated with a variety of high temperature chemical behavior. Trends are cited resulting from a number of thermodynamic and spectroscopic correlations involving solid phases, species in aqueous solution, and molecules and ions in the vapor phase. Inadequacies in the data and alternative approaches are discussed. The characterization of nonstoichiometric phases stable only at high temperatures is related to a network of heterogeneous and homogeneous equilibria. A broad perspective of similarity and dissimilarity between the lanthanides and actinides emerges and forms the basis of the projected needs for further study

Thermodynamic evaluation of Cu-H-O-S-P system - Phase stabilities and solubilities for OFP-copper

International Nuclear Information System (INIS)

Magnusson, Hans; Frisk, Karin

2013-04-01

A thermodynamic evaluation for Cu-H-O-S-P has been made, with special focus on the phase stabilities and solubilities for OFP-copper. All binary systems including copper have been reviewed. Gaseous species and stoichiometric crystalline phases have been included for higher systems. Sulphur in OFP-copper will be found in sulphides. The sulphide can take different morphologies but constant stoichiometry Cu 2 S. The solubility of sulphur in FCC-copper reaches ppm levels already at 550 deg C and decreases with lower temperature. No phosphorus-sulphide will be stable, although the copper sulphide can be replaced by copper sulphates at high partial pressure oxygen like in the oxide scale. Phosphorus has a high affinity to oxygen, and phosphorus oxide P 4 O 10 and copper phosphates (Cu 2 P 2 O 7 and Cu 3 (PO 4 ) 2 ) are all more stable than copper oxide Cu 2 O. With hydrogen present at atmospheric pressure, copper phosphates Cu 2 P 2 O 7 and Cu 3 (P 2 O 6 OH) 2 are both more stable than water vapour or aqueous water at temperatures below 400 deg C. At high pressure conditions, the copper phosphates can be reduced giving water. However, the phosphates are still more stable than water vapour. The solubility limit of phosphorus in FCC-copper at 25 deg C is 510 ppm, in equilibrium with copper phosphide Cu 3 P. The major part of phosphorus in OFP-copper will be in solid solution. Oxygen in FCC-copper has a very low solubility. In the presence of a strong oxide forming element such as phosphorus in OFP-copper, the solubility decreases even more. Copper oxides will become stable first when all phosphorus has been consumed, which takes place at twice the phosphorus content, calculated in weight. Hydrogen has a low solubility in copper, calculated as 0.1 ppm at 675 deg C. No crystalline hydrogen phase has been found stable at atmospheric pressures and above 400 deg C. At lower temperatures the hydrogen containing phosphate Cu 3 (P 2 O 6 OH) 2 can become stable. Measured hydrogen

Characterizing the information content of cloud thermodynamic phase retrievals from the notional PACE OCI shortwave reflectance measurements

Science.gov (United States)

Coddington, O. M.; Vukicevic, T.; Schmidt, K. S.; Platnick, S.

2017-08-01

We rigorously quantify the probability of liquid or ice thermodynamic phase using only shortwave spectral channels specific to the National Aeronautics and Space Administration's Moderate Resolution Imaging Spectroradiometer, Visible Infrared Imaging Radiometer Suite, and the notional future Plankton, Aerosol, Cloud, ocean Ecosystem imager. The results show that two shortwave-infrared channels (2135 and 2250 nm) provide more information on cloud thermodynamic phase than either channel alone; in one case, the probability of ice phase retrieval increases from 65 to 82% by combining 2135 and 2250 nm channels. The analysis is performed with a nonlinear statistical estimation approach, the GEneralized Nonlinear Retrieval Analysis (GENRA). The GENRA technique has previously been used to quantify the retrieval of cloud optical properties from passive shortwave observations, for an assumed thermodynamic phase. Here we present the methodology needed to extend the utility of GENRA to a binary thermodynamic phase space (i.e., liquid or ice). We apply formal information content metrics to quantify our results; two of these (mutual and conditional information) have not previously been used in the field of cloud studies.

A development of multi-Species mass transport model considering thermodynamic phase equilibrium

DEFF Research Database (Denmark)

Hosokawa, Yoshifumi; Yamada, Kazuo; Johannesson, Björn

2008-01-01

) variation in solid-phase composition when using different types of cement, (ii) physicochemical evaluation of steel corrosion initiation behaviour by calculating the molar ratio of chloride ion to hydroxide ion [Cl]/[OH] in pore solution, (iii) complicated changes of solid-phase composition caused......In this paper, a multi-species mass transport model, which can predict time dependent variation of pore solution and solid-phase composition due to the mass transport into the hardened cement paste, has been developed. Since most of the multi-species models established previously, based...... on the Poisson-Nernst-Planck theory, did not involve the modeling of chemical process, it has been coupled to thermodynamic equilibrium model in this study. By the coupling of thermodynamic equilibrium model, the multi-species model could simulate many different behaviours in hardened cement paste such as: (i...

Effects of thermal fluctuations on the thermodynamics of modified Hayward black hole

Energy Technology Data Exchange (ETDEWEB)

Pourhassan, Behnam [Damghan University, School of Physics, Damghan (Iran, Islamic Republic of); Faizal, Mir [University of Lethbridge, Department of Physics and Astronomy, Lethbridge, AB (Canada); Debnath, Ujjal [Indian Institute of Engineering Science and Technology, Shibpur, Department of Mathematics, Howrah (India)

2016-03-15

In this work, we analyze the effects of thermal fluctuations on the thermodynamics of a modified Hayward black hole. These thermal fluctuations will produce correction terms for various thermodynamical quantities like entropy, pressure, internal energy, and specific heats. We also investigate the effect of these correction terms on the first law of thermodynamics. Finally, we study the phase transition for the modified Hayward black hole. It is demonstrated that the modified Hayward black hole is stable even after the thermal fluctuations are taken into account, as long as the event horizon is larger than a certain critical value. (orig.)

Thermodynamic Modeling of Hydrogen Storage Capacity in Mg-Na Alloys

Science.gov (United States)

Abdessameud, S.; Mezbahul-Islam, M.; Medraj, M.

2014-01-01

Thermodynamic modeling of the H-Mg-Na system is performed for the first time in this work in order to understand the phase relationships in this system. A new thermodynamic description of the stable NaMgH3 hydride is performed and the thermodynamic models for the H-Mg, Mg-Na, and H-Na systems are reassessed using the modified quasichemical model for the liquid phase. The thermodynamic properties of the ternary system are estimated from the models of the binary systems and the ternary compound using CALPHAD technique. The constructed database is successfully used to reproduce the pressure-composition isotherms for MgH2 + 10 wt.% NaH mixtures. Also, the pressure-temperature equilibrium diagram and reaction paths for the same composition are predicted at different temperatures and pressures. Even though it is proved that H-Mg-Na does not meet the DOE hydrogen storage requirements for onboard applications, the best working temperatures and pressures to benefit from its full catalytic role are given. Also, the present database can be used for thermodynamic assessments of higher order systems. PMID:25383361

Black hole thermodynamics in Lovelock gravity's rainbow with (AdS asymptote

Directory of Open Access Journals (Sweden)

Seyed Hossein Hendi

2017-01-01

Full Text Available In this paper, we combine Lovelock gravity with gravity's rainbow to construct Lovelock gravity's rainbow. Considering the Lovelock gravity's rainbow coupled to linear and also nonlinear electromagnetic gauge fields, we present two new classes of topological black hole solutions. We compute conserved and thermodynamic quantities of these black holes (such as temperature, entropy, electric potential, charge and mass and show that these quantities satisfy the first law of thermodynamics. In order to study the thermal stability in canonical ensemble, we calculate the heat capacity and determinant of the Hessian matrix and show in what regions there are thermally stable phases for black holes. Also, we discuss the dependence of thermodynamic behavior and thermal stability of black holes on rainbow functions. Finally, we investigate the critical behavior of black holes in the extended phase space and study their interesting properties.

First Principles Investigation of the Mechanical, Thermodynamic and Electronic Properties of FeSn{sub 5} and CoSn{sub 5} Intermetallic Phases under Pressure

Energy Technology Data Exchange (ETDEWEB)

Sun, Wenming; Liu, Jing; Wang, Hong [China Building Materials Academy, Beijing (China); Zhang, Zhenwei [Linyi Academy of Technology Cooperation and Application, Linyi (China); Zhang, Liang [NeoTrident Technology Ltd., Shanghai (China); Bu, Yuxiang [Shandong University, Jinan (China)

2017-02-15

For guidance for developing Fe/Co-Sn-based anode materials for lithium-ion batteries, the mechanical, thermodynamic and electronic properties of FeSn{sub 5} and CoSn{sub 5} intermetallic phases under pressures ranging from 0 to 30 GPa have been investigated systematically using first-principles total-energy calculations within the framework of the generalized gradient approximation. The pressure was found to have significant effects on the mechanical, thermodynamic and electronic properties of these compounds. In the selected pressure range, CoSn{sub 5} has a more negative formation enthalpy than FeSn{sub 5}. Based on the calculated elastic constants, the bulk modulus, shear modulus, and Young's modulus were determined via the Viogt-Reuss-Hill averaging scheme. The variations of specific heats at constant volume for FeSn{sub 5} and CoSn{sub 5} in a wide pressure (0 - 30 GPa) and temperature (0 - 1000 K) range are also predicted from phonon density of states calculation. The calculated results suggested that both FeSn{sub 5} and CoSn{sub 5} are mechanically stable at pressure from 0 to 30 GPa. FeSn{sub 5} is dynamically stable at pressure up to, 30 GPa, at least, however, CoSn{sub 5} is dynamically stable no higher than 15 GPa.

Fe-solubility of Ni7S6 and Ni9S8: Thermodynamic analysis

International Nuclear Information System (INIS)

Waldner, P.

2011-01-01

Experimental data on phase equilibria have been used for thermodynamic analysis of the iron solubility of the nickel sulfides Ni 7 S 6 and Ni 9 S 8 . For both compounds, a two-sublattice approach within the framework of the compound energy formalism has been applied to perform Gibbs free energy modelling at 0.1 MPa total pressure consistently embedded in recent thermodynamic assessment studies of other iron-nickel-sulfides. The predicted maxima of iron solubility around 3 at% of Ni 7 S 6 and 5.5 at% of Ni 9 S 8 are confirmed by experimental data. The calculations of complex ternary phase relations with Fe-bearing Ni 7 S 6 and Ni 9 S 8 gain further improvement. The first internally consistent description of all thermodynamically stable phases known in the literature for the iron-nickel-sulfur system is completed.

Thermodynamics, phase transitions and Ruppeiner geometry for Einstein-dilaton-Lifshitz black holes in the presence of Maxwell and Born-Infeld electrodynamics

Energy Technology Data Exchange (ETDEWEB)

Zangeneh, M.K. [Shanghai Jiao Tong University, Department of Physics and Astronomy, Center of Astronomy and Astrophysics, Shanghai (China); Shiraz University, Physics Department and Biruni Observatory, Shiraz (Iran, Islamic Republic of); Shahid Chamran University of Ahvaz, Physics Department, Faculty of Science, Ahvaz (Iran, Islamic Republic of); Dehyadegari, A. [Shiraz University, Physics Department and Biruni Observatory, Shiraz (Iran, Islamic Republic of); Mehdizadeh, M.R. [Shahid Bahonar University, Department of Physics, P.O. Box 76175, Kerman (Iran, Islamic Republic of); Research Institute for Astrophysics and Astronomy of Maragha (RIAAM), P.O. Box 55134-441, Maragha (Iran, Islamic Republic of); Wang, B. [Shanghai Jiao Tong University, Department of Physics and Astronomy, Center of Astronomy and Astrophysics, Shanghai (China); Sheykhi, A. [Shiraz University, Physics Department and Biruni Observatory, Shiraz (Iran, Islamic Republic of); Research Institute for Astrophysics and Astronomy of Maragha (RIAAM), P.O. Box 55134-441, Maragha (Iran, Islamic Republic of)

2017-06-15

In this paper, we first obtain the higher-dimen-sional dilaton-Lifshitz black hole solutions in the presence of Born-Infeld (BI) electrodynamics. We find that there are two different solutions for the cases of z = n + 1 and z ≠ n + 1 where z is the dynamical critical exponent and n is the number of spatial dimensions. Calculating the conserved and thermodynamical quantities, we show that the first law of thermodynamics is satisfied for both cases. Then we turn to the study of different phase transitions for our Lifshitz black holes. We start with the Hawking-Page phase transition and explore the effects of different parameters of our model on it for both linearly and BI charged cases. After that, we discuss the phase transitions inside the black holes. We present the improved Davies quantities and prove that the phase transition points shown by them are coincident with the Ruppeiner ones. We show that the zero temperature phase transitions are transitions in the radiance properties of black holes by using the Landau-Lifshitz theory of thermodynamic fluctuations. Next, we turn to the study of the Ruppeiner geometry (thermodynamic geometry) for our solutions. We investigate thermal stability, interaction type of possible black hole molecules and phase transitions of our solutions for linearly and BI charged cases separately. For the linearly charged case, we show that there are no phase transitions at finite temperature for the case z ≥ 2. For z < 2, it is found that the number of finite temperature phase transition points depends on the value of the black hole charge and there are not more than two. When we have two finite temperature phase transition points, there is no thermally stable black hole between these two points and we have discontinuous small/large black hole phase transitions. As expected, for small black holes, we observe finite magnitude for the Ruppeiner invariant, which shows the finite correlation between possible black hole molecules, while

Thermodynamics, phase transitions and Ruppeiner geometry for Einstein-dilaton-Lifshitz black holes in the presence of Maxwell and Born-Infeld electrodynamics

International Nuclear Information System (INIS)

Zangeneh, M.K.; Dehyadegari, A.; Mehdizadeh, M.R.; Wang, B.; Sheykhi, A.

2017-01-01

In this paper, we first obtain the higher-dimen-sional dilaton-Lifshitz black hole solutions in the presence of Born-Infeld (BI) electrodynamics. We find that there are two different solutions for the cases of z = n + 1 and z ≠ n + 1 where z is the dynamical critical exponent and n is the number of spatial dimensions. Calculating the conserved and thermodynamical quantities, we show that the first law of thermodynamics is satisfied for both cases. Then we turn to the study of different phase transitions for our Lifshitz black holes. We start with the Hawking-Page phase transition and explore the effects of different parameters of our model on it for both linearly and BI charged cases. After that, we discuss the phase transitions inside the black holes. We present the improved Davies quantities and prove that the phase transition points shown by them are coincident with the Ruppeiner ones. We show that the zero temperature phase transitions are transitions in the radiance properties of black holes by using the Landau-Lifshitz theory of thermodynamic fluctuations. Next, we turn to the study of the Ruppeiner geometry (thermodynamic geometry) for our solutions. We investigate thermal stability, interaction type of possible black hole molecules and phase transitions of our solutions for linearly and BI charged cases separately. For the linearly charged case, we show that there are no phase transitions at finite temperature for the case z ≥ 2. For z < 2, it is found that the number of finite temperature phase transition points depends on the value of the black hole charge and there are not more than two. When we have two finite temperature phase transition points, there is no thermally stable black hole between these two points and we have discontinuous small/large black hole phase transitions. As expected, for small black holes, we observe finite magnitude for the Ruppeiner invariant, which shows the finite correlation between possible black hole molecules, while

New stable phase in binary Fe-Nd

International Nuclear Information System (INIS)

Schneider, G.; Landgraf, F.J.G.; Villas-Boas, V.; Bezerra, G.H.; Missell, F.P.; Ray, A.E.

1992-01-01

An investigation of binary Fe-Nd alloys revealed the existence of an oxygen-free, stable Fe-rich phase A 2 , formed peritecticly in the range 750-800 deg C. EPMA shows this phase to contain 22.8 atomic percent Nd. This ferromagnetic phase has T c = 230 de C, but is magnetically soft. The X-ray diffraction pattern can be indexed using a hexagonal cell with a = 2.021 nm. and c = 1.235 nm. (author)

The influence of thermodynamic self-consistency on the phase behaviour of symmetric binary mixtures

CERN Document Server

Scholl-Paschinger, E; Kahl, G

2004-01-01

We have investigated the phase behaviour of a symmetric binary mixture with particles interacting via hard-core Yukawa potentials. To calculate the thermodynamic properties we have used the mean spherical approximation (MSA), a conventional liquid state theory, and the closely related self-consistent Ornstein-Zernike approximation which is defined via an MSA-type closure relation, requiring, in addition, thermodynamic self-consistency between the compressibility and the energy-route. We investigate on a quantitative level the effect of the self-consistency requirement on the phase diagram and on the critical behaviour and confirm the existence of three archetypes of phase diagram, which originate from the competition between the first order liquid/vapour transition and the second order demixing transition.

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

Stability of black holes based on horizon thermodynamics

Directory of Open Access Journals (Sweden)

Meng-Sen Ma

2015-12-01

Full Text Available On the basis of horizon thermodynamics we study the thermodynamic stability of black holes constructed in general relativity and Gauss–Bonnet gravity. In the framework of horizon thermodynamics there are only five thermodynamic variables E, P, V, T, S. It is not necessary to consider concrete matter fields, which may contribute to the pressure of black hole thermodynamic system. In non-vacuum cases, we can derive the equation of state, P=P(V,T. According to the requirements of stable equilibrium in conventional thermodynamics, we start from these thermodynamic variables to calculate the heat capacity at constant pressure and Gibbs free energy and analyze the local and global thermodynamic stability of black holes. It is shown that P>0 is the necessary condition for black holes in general relativity to be thermodynamically stable, however this condition cannot be satisfied by many black holes in general relativity. For black hole in Gauss–Bonnet gravity negative pressure can be feasible, but only local stable black hole exists in this case.

Theory of the thermodynamic influence of solution-phase additives in shape-controlled nanocrystal synthesis.

Science.gov (United States)

Qi, Xin; Fichthorn, Kristen A

2017-10-19

Though many experimental studies have documented that certain solution-phase additives can play a key role in the shape-selective synthesis of metal nanocrystals, the origins and mechanisms of this shape selectivity are still unclear. One possible role of such molecules is to thermodynamically induce the equilibrium shape of a nanocrystal by altering the interfacial free energies of the facets. Using a multi-scheme thermodynamic integration method that we recently developed [J. Chem. Phys., 2016, 145, 194108], we calculate the solid-liquid interfacial free energies γ sl and investigate the propensity to achieve equilibrium shapes in such syntheses. We first apply this method to Ag(100) and Ag(111) facets in ethylene glycol solution containing polyvinylpyrrolidone (PVP), to mimic the environment in polyol synthesis of Ag nanocrystals. We find that although PVP has a preferred binding to Ag(100), its selectivity is not sufficient to induce a thermodynamic preference for {100}-faceted nanocubes, as has been observed experimentally. This indicates that PVP promotes Ag nanocube formation kinetically rather than thermodynamically. We further quantify the thermodynamic influence of adsorbed solution-phase additives for generic molecules, by building a γ sl ratio/nanocrystal shape map as a function of zero-temperature binding energies. This map can be used to gauge the efficacy of candidate additive molecules for producing targeted thermodynamic nanocrystal shapes. The results indicate that only additives with a strong facet selectivity can impart significant thermodynamic-shape change. Therefore, many of the nanocrystals observed in experiments are likely kinetic products.

Black hole thermodynamics in Lovelock gravity's rainbow with (A)dS asymptote

Science.gov (United States)

Hendi, Seyed Hossein; Dehghani, Ali; Faizal, Mir

2017-01-01

In this paper, we combine Lovelock gravity with gravity's rainbow to construct Lovelock gravity's rainbow. Considering the Lovelock gravity's rainbow coupled to linear and also nonlinear electromagnetic gauge fields, we present two new classes of topological black hole solutions. We compute conserved and thermodynamic quantities of these black holes (such as temperature, entropy, electric potential, charge and mass) and show that these quantities satisfy the first law of thermodynamics. In order to study the thermal stability in canonical ensemble, we calculate the heat capacity and determinant of the Hessian matrix and show in what regions there are thermally stable phases for black holes. Also, we discuss the dependence of thermodynamic behavior and thermal stability of black holes on rainbow functions. Finally, we investigate the critical behavior of black holes in the extended phase space and study their interesting properties.

Thermodynamic stability of actinide pyrochlore minerals in deep geologic repository environments

International Nuclear Information System (INIS)

Wang, YIFENG; Xu, HUIFANG

2000-01-01

Crystalline phases of pyrochlore (e.g., CaPuTi 2 O 7 , CaUTi 2 O 7 ) have been proposed as a durable ceramic waste form for disposal of high level radioactive wastes including surplus weapons-usable plutonium. In this paper, the authors use a linear free energy relationship to predict the Gibbs free energies of formation of pyrochlore phases (CaMTi 2 O 7 ). The Pu-pyrochlore phase is predicted to be stable with respect to PuO 2 , CaTiO 3 , and TiO 2 at room temperatures. Pu-pyrochlore is expected to be stable in a geologic repository where silica and carbonate components are absent or limited. The authors suggest that a repository in a salt formation be an ideal environment for disposal of high level, pyrochlore-based ceramic wastes. In such environment, adding CaO as a backfill will make pyrochlore minerals thermodynamically stable and therefore effectively prevent actinide release from these mineral phases

Phase stability, electronic, elastic and thermodynamic properties of Al-RE intermetallics in Mg-Al-RE alloy: A first principles study

Directory of Open Access Journals (Sweden)

H.L. Chen

2015-09-01

Full Text Available Electronic structure and elastic properties of Al2Y, Al3Y, Al2Gd and Al3Gd phases were investigated by means of first-principles calculations from CASTEP program based on density functional theory (DFT. The ground state energy and elastic constants of each phase were calculated, the formation enthalpy (ΔH, bulk modulus (B, shear modulus (G, Young's modulus (E, Poisson's ratio (ν and anisotropic coefficient (A were derived. The formation enthalpy shows that Al2RE is more stable than Al3RE, and Al-Y intermetallics have stronger phase stability than Al-Gd intermetallics. The calculated mechanical properties indicate that all these four intermetallics are strong and hard brittle phases, it may lead to the similar performance when deforming due to their similar elastic constants. The total and partial electron density of states (DOS, Mulliken population and metallicity were calculated to analyze the electron structure and bonding characteristics of the phases. Finally, phonon calculation was conducted, and the thermodynamic properties were obtained and further discussed.

Thermodynamically stable amyloid-β monomers have much lower membrane affinity than the small oligomers

Directory of Open Access Journals (Sweden)

Bidyut eSarkar

2013-04-01

Full Text Available Amyloid beta (Aβ is an extracellular 39-43 residue long peptide present in the mammalian cerebrospinal fluid, whose aggregation is associated with Alzheimer’s disease. Small oligomers of Aβ are currently thought to be the key to toxicity. However, it is not clear why the monomers of Aβ are non-toxic, and at what stage of aggregation toxicity emerges. Interactions of Aβ with cell membranes is thought to be the initiator of toxicity, but membrane-binding studies with different preparations of monomers and oligomers have not settled this issue. We have earlier found that thermodynamically stable Aβ monomers emerge spontaneously from oligomeric mixtures upon long term incubation in physiological solutions (Nag et al, JBC, 2011. Here we show that the membrane-affinity of these stable Aβ monomers is much lower than that of a mixture of small oligomers (containing dimers to decamers, providing a clue to the emergence of toxicity. Fluorescently labeled Aβ40 monomers show negligible binding to cell membranes of a neuronal cell line (RN46A at physiological concentrations (250 nM, while oligomers at the same concentrations show strong binding within 30 minutes of incubation. The increased affinity most likely does not require any specific neuronal receptor, since this difference in membrane-affinity was also observed in a somatic cell-line (HEK 293T. Similar results are also obtained for Aβ42 monomers and oligomers. Minimal amount of cell death is observed at these concentrations even after 36 hours of incubation. It is likely that membrane binding precedes subsequent slower toxic events induced by Aβ. Our results a provide an explanation for the non-toxic nature of Aβ monomers, b suggest that Aβ toxicity emerges at the initial oligomeric phase, and c provide a quick assay for monitoring the benign-to-toxic transformation of Aβ.

Thermodynamic modeling of the CeO{sub 2}–CoO nano-phase diagram

Energy Technology Data Exchange (ETDEWEB)

Kim, Sung S., E-mail: sungkim@wow.hongik.ac.kr

2014-03-05

Highlights: • The CeO{sub 2}–CoO nano-phase diagram was modeled thermodynamically. • The surface energies of the solution phases were modeled with Butler’s equation. • The present work agreed with the experimental work on the nanoparticle sintering. -- Abstract: A nano-phase diagram of the CeO{sub 2}–CoO system was modeled thermodynamically with experimental data available in the literatures. The surface energies of CeO{sub 2} and CoO unavailable in the literatures were estimated reasonably on the thermodynamic basis. Butler’s model was used to describe the surface energy and the surface composition of the solution phases and then the nano interaction parameters on the particle radius were assessed through the multiple linear regression method. A consistent set of optimized interaction parameters in the present system was derived for describing the Gibbs energy of liquid, fluorite, and halite solution phases as a function of particle radius. The eutectic temperatures calculated in the present work interpreted well the experimental data for the unusual low sintering temperature of the nanoparticles with the tri-modal particle size distribution. Furthermore, with the aid of the present result, the microstructure evolution in the CGO–CoO system during the nanoparticle sintering was described reasonably. It is concluded that the present modeling will be a good guide for the condition of the liquid phase sintering to obtain the rapid densification of the nanoparticles at lower temperatures.

An empirical method for calculating thermodynamic parameters for U(6) phases, applications to performance assessment calculations

International Nuclear Information System (INIS)

Ewing, R.C.; Chen, F.; Clark, S.B.

2002-01-01

Uranyl minerals form by oxidation and alteration of uraninite, UO 2+x , and the UO 2 in used nuclear fuels. The thermodynamic database for these phases is extremely limited. However, the Gibbs free energies and enthalpies for uranyl phases may be estimated based on a method that sums polyhedral contributions. The molar contributions of the structural components to Δ f G m 0 and Δ f H m 0 are derived by multiple regression using the thermodynamic data of phases for which the crystal structures are known. In comparison with experimentally determined values, the average residuals associated with the predicted Δ f G m 0 and Δ f H m 0 for the uranyl phases used in the model are 0.08 and 0.10%, respectively. There is also good agreement between the predicted mineral stability relations and field occurrences, thus providing confidence in this method for the estimation of Δ f G m 0 and Δ f H m 0 of the U(VI) phases. This approach provides a means of generating estimated thermodynamic data for performance assessment calcination and a basic for making bounding calcination of phase stabilities and solubilities. (author)

Thermodynamic evaluation of Cu-H-O-S-P system - Phase stabilities and solubilities for OFP-copper

Energy Technology Data Exchange (ETDEWEB)

Magnusson, Hans; Frisk, Karin [Swerea KIMAB, Kista (Sweden)

2013-04-15

A thermodynamic evaluation for Cu-H-O-S-P has been made, with special focus on the phase stabilities and solubilities for OFP-copper. All binary systems including copper have been reviewed. Gaseous species and stoichiometric crystalline phases have been included for higher systems. Sulphur in OFP-copper will be found in sulphides. The sulphide can take different morphologies but constant stoichiometry Cu{sub 2}S. The solubility of sulphur in FCC-copper reaches ppm levels already at 550 deg C and decreases with lower temperature. No phosphorus-sulphide will be stable, although the copper sulphide can be replaced by copper sulphates at high partial pressure oxygen like in the oxide scale. Phosphorus has a high affinity to oxygen, and phosphorus oxide P{sub 4}O{sub 10} and copper phosphates (Cu{sub 2}P{sub 2}O{sub 7} and Cu{sub 3}(PO{sub 4}){sub 2}) are all more stable than copper oxide Cu{sub 2}O. With hydrogen present at atmospheric pressure, copper phosphates Cu{sub 2}P{sub 2}O{sub 7} and Cu{sub 3}(P{sub 2}O{sub 6}OH){sub 2} are both more stable than water vapour or aqueous water at temperatures below 400 deg C. At high pressure conditions, the copper phosphates can be reduced giving water. However, the phosphates are still more stable than water vapour. The solubility limit of phosphorus in FCC-copper at 25 deg C is 510 ppm, in equilibrium with copper phosphide Cu{sub 3}P. The major part of phosphorus in OFP-copper will be in solid solution. Oxygen in FCC-copper has a very low solubility. In the presence of a strong oxide forming element such as phosphorus in OFP-copper, the solubility decreases even more. Copper oxides will become stable first when all phosphorus has been consumed, which takes place at twice the phosphorus content, calculated in weight. Hydrogen has a low solubility in copper, calculated as 0.1 ppm at 675 deg C. No crystalline hydrogen phase has been found stable at atmospheric pressures and above 400 deg C. At lower temperatures the hydrogen

Thermodynamics of the sorption of water-soluble vitamins in reverse-phase high performance liquid chromatography

Science.gov (United States)

Chirkin, V. A.; Karpov, S. I.; Selemenev, V. F.

2012-12-01

The thermodynamics of the sorption of certain water-soluble vitamins on a C18 reverse phase from water-acetonitrile solutions of different compositions is studied. The thermodynamic characteristics of the investigated chromatographic systems are calculated. The dependences of standard molar enthalpy and changes in entropy when the sorbate transfers from the bulk solution to the surface layer on the concentration of the organic component in the mobile phase are analyzed. The boundaries for applying the main retention models describing the sorption of the investigated compounds are discussed.

Global spectroscopic survey of cloud thermodynamic phase at high spatial resolution, 2005-2015

Science.gov (United States)

Thompson, David R.; Kahn, Brian H.; Green, Robert O.; Chien, Steve A.; Middleton, Elizabeth M.; Tran, Daniel Q.

2018-02-01

The distribution of ice, liquid, and mixed phase clouds is important for Earth's planetary radiation budget, impacting cloud optical properties, evolution, and solar reflectivity. Most remote orbital thermodynamic phase measurements observe kilometer scales and are insensitive to mixed phases. This under-constrains important processes with outsize radiative forcing impact, such as spatial partitioning in mixed phase clouds. To date, the fine spatial structure of cloud phase has not been measured at global scales. Imaging spectroscopy of reflected solar energy from 1.4 to 1.8 µm can address this gap: it directly measures ice and water absorption, a robust indicator of cloud top thermodynamic phase, with spatial resolution of tens to hundreds of meters. We report the first such global high spatial resolution survey based on data from 2005 to 2015 acquired by the Hyperion imaging spectrometer onboard NASA's Earth Observer 1 (EO-1) spacecraft. Seasonal and latitudinal distributions corroborate observations by the Atmospheric Infrared Sounder (AIRS). For extratropical cloud systems, just 25 % of variance observed at GCM grid scales of 100 km was related to irreducible measurement error, while 75 % was explained by spatial correlations possible at finer resolutions.

Thermodynamic Property Model of Wide-Fluid Phase Propane

Directory of Open Access Journals (Sweden)

I Made Astina

2007-05-01

Full Text Available A new thermodynamic property model for propane is expressed in form of the Helmholtz free energy function. It consists of eight terms of the ideal-gas part and eighteen terms of the residual part. Accurate experimental data of fluid properties and theoretical approach from the intermolecular potential were simultaneously considered in the development to insure accuracy and to improve reliability of the equation of state over wide range of pressures and temperatures. Based on the state range of experimental data used in the model development, the validity range is judged from the triple-point of 85.48 K to temperature of 450 K and pressure up to 60 MPa. The uncertainties with respect to different properties are estimated to be 0.03% in ideal-gas isobaric specific heat, 0.2% in liquid phase density, 0.3% in gaseous phase density 1% in specific heats, 0.1% in vapor-pressure except at very low temperatures, 0.05% in saturated-liquid density, 0.02% in speed of sound of the gaseous phase and 1% in speed of sound of the liquid phase.

Extended phase space thermodynamics and P-V criticality: Brans-Dicke-Born-Infeld vs. Einstein-Born-Infeld-dilaton black holes

Energy Technology Data Exchange (ETDEWEB)

Hendi, S.H. [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), P. O. Box 55134-441, Maragha (Iran, Islamic Republic of); Tad, R.M.; Armanfard, Z.; Talezadeh, M.S. [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of)

2016-05-15

Motivated by a thermodynamic analogy of black holes and Van der Waals liquid/gas systems, in this paper, we study P-V criticality of both dilatonic Born-Infeld black holes and their conformal solutions, Brans-Dicke-Born-Infeld solutions. Due to the conformal constraint, we have to neglect the old Lagrangian of dilatonic Born-Infeld theory and its black hole solutions, and introduce a new one. We obtain spherically symmetric nonlinearly charged black hole solutions in both Einstein and Jordan frames and then we calculate the related conserved and thermodynamic quantities. After that, we extend the phase space by considering the proportionality of the cosmological constant and thermodynamical pressure. We obtain critical values of the thermodynamic coordinates through numerical methods and plot the relevant P-V and G-T diagrams. Investigation of the mentioned diagrams helps us to study the thermodynamical phase transition. We also analyze the effects of varying different parameters on the phase transition of black holes. (orig.)

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

International Nuclear Information System (INIS)

Premović, Milena; Minić, Duško; Manasijević, Dragan; Ćosović, Vladan; Živković, Dragana; Dervišević, Irma

2015-01-01

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

Experimental investigation of the Ag–Bi–I ternary system and thermodynamic properties of the ternary phases

International Nuclear Information System (INIS)

Mashadieva, Leyla F.; Aliev, Ziya S.; Shevelkov, Andrei V.; Babanly, Mahammad B.

2013-01-01

Highlights: ► The self-consistent phase diagram of the Ag–Bi–I system is constructed. ► Ag 2 BiI 5 and AgBi 2 I 7 are the only ternary phases of the system. ► Standard thermodynamic functions of formation and the standard entropies of Ag 2 BiI 5 and AgBi 2 I 7 are calculated. - Abstract: The phase equilibriums in the Ag–Bi–I ternary system and thermodynamic properties of the ternary phases were experimentally determined by using DTA and XRD techniques and EMF measurements with the Ag 4 RbI 5 solid electrolyte. According to the obtained experimental results, the polythermal sections of the ternary phase diagram, its isothermal section at 300 K as well as the projection of the liquids surface have been revised. The fields of the primary crystallization and types and coordinates of nonvariant and monovariant equilibriums were determined. The partial molar functions of silver iodide and silver in the alloys as well as the standard thermodynamic functions of formation and the standard entropies of Ag 2 BiI 5 and AgBi 2 I 7 were calculated based on EMF measurements.

Thermodynamics and structure of liquid metals from a consistent optimized random phase approximation

International Nuclear Information System (INIS)

Akinlade, O.; Badirkhan, Z.; Pastore, G.

2000-05-01

We study thermodynamics and structural properties of several liquid metals to assess the validity of the generalized non-local model potential (GNMP) of Li et. al. [J.Phys. F16,309 (1986)]. By using a new thermodynamically consistent version of the optimized random phase approximation (ORPA), especially adapted to continuous reference potentials, we improve our previous results obtained within the variational approach based on the Gibbs - Bogoliubov inequality. Hinging on the unified and very accurate evaluation of structure factors and thermodynamic quantities provided by the ORPA, we find that the GNMP yields satisfactory results for the alkali metals, however, those for the polyvalent metals point to a substantial inadequacy of the GNMP for high valence systems. (author)

Contact symmetries and Hamiltonian thermodynamics

International Nuclear Information System (INIS)

Bravetti, A.; Lopez-Monsalvo, C.S.; Nettel, F.

2015-01-01

It has been shown that contact geometry is the proper framework underlying classical thermodynamics and that thermodynamic fluctuations are captured by an additional metric structure related to Fisher’s Information Matrix. In this work we analyse several unaddressed aspects about the application of contact and metric geometry to thermodynamics. We consider here the Thermodynamic Phase Space and start by investigating the role of gauge transformations and Legendre symmetries for metric contact manifolds and their significance in thermodynamics. Then we present a novel mathematical characterization of first order phase transitions as equilibrium processes on the Thermodynamic Phase Space for which the Legendre symmetry is broken. Moreover, we use contact Hamiltonian dynamics to represent thermodynamic processes in a way that resembles the classical Hamiltonian formulation of conservative mechanics and we show that the relevant Hamiltonian coincides with the irreversible entropy production along thermodynamic processes. Therefore, we use such property to give a geometric definition of thermodynamically admissible fluctuations according to the Second Law of thermodynamics. Finally, we show that the length of a curve describing a thermodynamic process measures its entropy production

Thermodynamics, stability and Hawking-Page transition of Kerr black holes from Renyi statistics

Energy Technology Data Exchange (ETDEWEB)

Czinner, Viktor G. [University of Lisbon, Multidisciplinary Center for Astrophysics and Department of Physics, Instituto Superior Tecnico, Lisboa (Portugal); HAS Wigner Research Centre for Physics, Budapest (Hungary); Iguchi, Hideo [Nihon University, Laboratory of Physics, College of Science and Technology, Funabashi, Chiba (Japan)

2017-12-15

Thermodynamics of rotating black holes described by the Renyi formula as equilibrium and zeroth law compatible entropy function is investigated. We show that similarly to the standard Boltzmann approach, isolated Kerr black holes are stable with respect to axisymmetric perturbations in the Renyi model. On the other hand, when the black holes are surrounded by a bath of thermal radiation, slowly rotating black holes can also be in stable equilibrium with the heat bath at a fixed temperature, in contrast to the Boltzmann description. For the question of possible phase transitions in the system, we show that a Hawking-Page transition and a first order small black hole/large black hole transition occur, analogous to the picture of rotating black holes in AdS space. These results confirm the similarity between the Renyi-asymptotically flat and Boltzmann-AdS approaches to black hole thermodynamics in the rotating case as well. We derive the relations between the thermodynamic parameters based on this correspondence. (orig.)

Thermodynamic analysis of 6xxx series Al alloys: Phase fraction diagrams

OpenAIRE

Cui S.; Mishra R.; Jung I.-H.

2018-01-01

Microstructural evolution of 6xxx Al alloys during various metallurgical processes was analyzed using accurate thermodynamic database. Phase fractions of all the possible precipitate phases which can form in the as-cast and equilibrium states of the Al-Mg-Si-Cu-Fe-Mn-Cr alloys were calculated over the technically useful composition range. The influence of minor elements such as Cu, Fe, Mn, and Cr on the amount of each type of precipitate in the as-cast and equilibrium conditions were analyzed...

Liquid-gas phase transition in hot nuclei: correlation between dynamical and thermodynamical signals

Energy Technology Data Exchange (ETDEWEB)

Rivet, M.F.; Borderie, B.; Desesquelles, P.; Galichet, E. [Institut de Physique Nucleaire, IN2P3-CNRS, 91 - Orsay (France); Bougault, R.; Le Neindre, N. [Caen Univ, LPC, IN2P3-CNRS, ISMRA, 14 - Caen (France); Galichet, E. [Conservatoire National des Arts et Metiers, 75 - Paris (France); Guiot, B.; Wieleczko, J.P. [GANIL, CEA et IN2P3-CNRS, 14 - Caen (France); Parlog, M.; Tabacaru, G. [Nat. Inst. for Physics and Nuclear Engineering, Bucharest-Magurele (Romania)

2003-07-01

The dynamics and thermodynamics of phase transition in hot nuclei are studied through experimental results on multifragmentation of heavy systems (A(projectile) + A(target) > 200) formed in central heavy ion collisions. Different signals such as negative heat capacity and spinodal decomposition, indicative of a phase transition studied in the INDRA collaboration are presented and their consistency is stressed. (authors)

Thermodynamics of pairing phase transition in nuclei

International Nuclear Information System (INIS)

Karim, Afaque; Ahmad, Shakeb

2014-01-01

The pairing gaps, pairing energy, heat capacity and entropy are calculated within BCS (Bardeen- Cooper-Schrieffer) based quasi particle approach, including thermal fluctuations on pairing field within pairing model for all nuclei (light, medium, heavy and super heavy nuclei). Quasi particles approach in BCS theory was introduced and reformulated to study various properties. For thermodynamic behavior of nuclei at finite temperatures, the anomalous averages of creation and annihilation operators are introduced. It is solved self consistently at finite temperatures to obtain BCS Hamiltonian. After doing unitary transformation, we obtained the Hamiltonian in the diagonal form. Thus, one gets temperature dependence gap parameter and pairing energy for nuclei. Moreover, the energy at finite temperatures is the sum of the condensation energy and the thermal energy of fermionic quasi particles. With the help of BCS Hamiltonian, specific heat, entropy and free energy are calculated for different nuclei. In this paper the gap parameter occupation number and pairing energy as a function of temperature which is important for all the light, medium, heavy and super heavy nuclei is calculated. Moreover, the various thermo dynamical quantities like specific heat, entropy and free energy is also obtained for different nuclei. Thus, the thermodynamics of pairing phase transition in nuclei is studied

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

International Nuclear Information System (INIS)

Fuertauer, Siegfried; Beutl, Alexander; Flanorfer, Hans; Henriques, David; Giel, Hans; Markus, Thorsten

2017-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2017-11-15

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

First-principles study of the elastic and thermodynamic properties of thorium hydrides at high pressure

International Nuclear Information System (INIS)

Zhang Xiao-Lin; Wu Yuan-Yuan; Shao Xiao-Hong; Lu Yong; Zhang Ping

2016-01-01

The high pressure behaviors of Th 4 H 15 and ThH 2 are investigated by using the first-principles calculations based on the density functional theory (DFT). From the energy–volume relations, the bct phase of ThH 2 is more stable than the fcc phase at ambient conditions. At high pressure, the bct ThH 2 and bcc Th 4 H 15 phases are more brittle than they are at ambient pressure from the calculated elastic constants and the Poisson ratio. The thermodynamic stability of the bct phase ThH 2 is determined from the calculated phonon dispersion. In the pressure domain of interest, the phonon dispersions of bcc Th 4 H 15 and bct ThH 2 are positive, indicating the dynamical stability of these two phases, while the fcc ThH 2 is unstable. The thermodynamic properties including the lattice vibration energy, entropy, and specific heat are predicted for these stable phases. The vibrational free energy decreases with the increase of the temperature, and the entropy and the heat capacity are proportional to the temperature and inversely proportional to the pressure. As the pressure increases, the resistance to the external pressure is strengthened for Th 4 H 15 and ThH 2 . (paper)

Experimental investigation and thermodynamic calculations of the Ag–Bi–Ga phase diagram

International Nuclear Information System (INIS)

Minić, Duško; Premović, Milena; Manasijević, Dragan; Ćosović, Vladan; Živković, Dragana; Marković, Aleksandar

2015-01-01

Phase diagram of the Ag–Bi–Ga ternary system was investigated using differential thermal analysis (DTA), scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS), and x-ray powder diffraction (XRD) methods. Experimentally obtained results were compared with the results of thermodynamic prediction of phase equilibria based on calculation of phase diagram (CALPHAD) method. Phase transition temperatures of alloys with overall compositions along three selected vertical sections Ag–Bi 50 Ga 50 , Bi–Ag 50 Ga 50 and Ga–Ag 50 Bi 50 were measured by DTA. Liquidus temperatures were experimentally determined and compared with the results of thermodynamic calculation. Identification of coexisting phases in samples equilibrated at 200 °C was carried out using SEM-EDS and XRD methods. Obtained results were compared with the calculated isothermal section of the Ag–Bi–Ga ternary system at corresponding temperature. Calculated liquidus projection and invariant equilibria of the Ag–Bi–Ga ternary system were presented. The obtained values were found to be in a close agreement. - Highlights: • Calculated constitutive binary system based on literature data. • Experimentally determined (DTA) temperatures of phase transformations compared with analytical calculation. • Definition of three vertical sections Ag–Bi 50 Ga 50 , Bi–Ag 50 Ga 50 and Ga–Ag 50 Bi 50 . • Calculated horizontal section at 200 °C, confirmed by experimental SEM-EDS and XRD method. • Calculated liquidus surface projection and determined invariant reaction occurred in ternary Ag–Bi–Ga system

Phase-field simulation of solidification in multicomponent alloys coupled with thermodynamic and diffusion mobility databases

International Nuclear Information System (INIS)

Zhang Ruijie; Jing Tao; Jie Wanqi; Liu Baicheng

2006-01-01

To simulate quantitatively the microstructural evolution in the solidification process of multicomponent alloys, we extend the phase-field model for binary alloys to multicomponent alloys with consideration of the solute interactions between different species. These interactions have a great influence not only on the phase equilibria but also on the solute diffusion behaviors. In the model, the interface region is assumed to be a mixture of solid and liquid with the same chemical potential, but with different compositions. The simulation presented is coupled with thermodynamic and diffusion mobility databases, which can accurately predict the phase equilibria and the solute diffusion transportation in the whole system. The phase equilibria in the interface and other thermodynamic quantities are obtained using Thermo-Calc through the TQ interface. As an example, two-dimensional computations for the dendritic growth in Al-Cu-Mg ternary alloy are performed. The quantitative solute distributions and diffusion matrix are obtained in both solid and liquid phases

Stability range of MoC (hp2). II. Thermodynamic properties of generalized Lewis acid-base intermetallics

International Nuclear Information System (INIS)

Koukouvetakis, J.

1988-01-01

The γ-MoC phase with the hexagonal WC structure was prepared without the presence of metal stabilizers at temperatures below 1000 degree C. This phase was found to be thermodynamically stable at low temperatures and decomposed to Mo 2 C and graphite at 1400 K. Using equilibrium and thermodynamic data, the thermodynamic quantities of this phase were calculated. Oxide equilibration and solid-state galvanic cell experiments were used to study thermodynamic properties of binary Lewis acid-base stabilized transition-metal alloys. The activity of vanadium was determined in alloys of vanadium with platinum-group metals such as Rh, Pd, and Ir at 1000 degree C. The activities of titanium in titanium-iridium alloys and of niobium in Nb 3 Ir were determined at 1400 degree C. The ternary phase diagram of V-Pd-O at 1000 degree C was obtained. Based on the vanadium-palladium results, a partial titration curve of palladium by vanadium was constructed. The excess partial molar Gibbs free energy of vanadium at infinite dilution was found to be -36.4 kcal mol -1 at 1000 degree C. Results are in agreement with the predictions of Brewer's theory of transition-metal alloy acid-base behavior

Thermodynamic properties of bulk and confined water

Energy Technology Data Exchange (ETDEWEB)

Mallamace, Francesco, E-mail: francesco.mallamace@unime.it [Dipartimento di Fisica e Scienza della Terra Università di Messina and CNISM, I-98168 Messina (Italy); Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Center for Polymer Studies and Department of Physics, Boston University, Boston, Massachusetts 02215 (United States); Corsaro, Carmelo [Dipartimento di Fisica e Scienza della Terra Università di Messina and CNISM, I-98168 Messina (Italy); Mallamace, Domenico [Dipartimento di Scienze dell' Ambiente, della Sicurezza, del Territorio, degli Alimenti e della Salute, Università di Messina, I-98166 Messina (Italy); Vasi, Sebastiano; Vasi, Cirino [IPCF-CNR, I-98166 Messina (Italy); Stanley, H. Eugene [Center for Polymer Studies and Department of Physics, Boston University, Boston, Massachusetts 02215 (United States)

2014-11-14

The thermodynamic response functions of water display anomalous behaviors. We study these anomalous behaviors in bulk and confined water. We use nuclear magnetic resonance (NMR) to examine the configurational specific heat and the transport parameters in both the thermal stable and the metastable supercooled phases. The data we obtain suggest that there is a behavior common to both phases: that the dynamics of water exhibit two singular temperatures belonging to the supercooled and the stable phase, respectively. One is the dynamic fragile-to-strong crossover temperature (T{sub L} ≃ 225 K). The second, T{sup *} ∼ 315 ± 5 K, is a special locus of the isothermal compressibility K{sub T}(T, P) and the thermal expansion coefficient α{sub P}(T, P) in the P–T plane. In the case of water confined inside a protein, we observe that these two temperatures mark, respectively, the onset of protein flexibility from its low temperature glass state (T{sub L}) and the onset of the unfolding process (T{sup *})

Thermodynamic and kinetics models of hydrogen absorption bound to phase transformations

International Nuclear Information System (INIS)

Gondor, G.; Lexcellent, Ch.

2007-01-01

In order to design hydrogen gaseous pressure tanks, the absorption (desorption) of hydrogen has to be described and modelled. The equilibrium state can be described by the 'H 2 gas pressure - H 2 composition in the intermetallic compounds - isotherms' (PCI) curves. Several models of PCI curves already exist. At the beginning of the absorption, the hydrogen atoms and the intermetallic compounds form a solid solution (α phase). When the hydrogen concentration increases, a phase transformation appears changing the α solid solution into an hydride (β phase) (solid solution + H 2 ↔ hydride). When all the solid solution has been transformed into hydride, the absorbed hydrogen atoms are in β phase. A new thermodynamic model has been developed in order to take into account this transition phase. The equilibrium state is then given by a relation between the H 2 gas pressure and the H 2 concentration in the intermetallic compound for a fixed external temperature. Two kinetics models have been developed too; at first has been considered that the kinetics depend only of the entire concentration in the intermetallic compound and of the difference between the applied pressure and the equilibrium pressure. Then, has been considered that the hydrogen concentration changes in the metallic matrix. In this last case, for each hydrogenation process, the absorption velocity is calculated to determine the slowest local process which regulates the local evolution of the hydrogen concentration. These two models are based on the preceding thermodynamic model of the PCI curves. (O.M.)

Partition thermodynamics of ionic surfactants between phosphatidylcholine vesicle and water phases

Science.gov (United States)

Chu, Shin-Chi; Hung, Chia-Hui; Wang, Shun-Cheng; Tsao, Heng-Kwong

2003-08-01

The partition of ionic surfactants (sodium alkyl sulfate and alkyl trimethyl ammonium bromide) between phosphatidylcholine vesicles and aqueous phase is investigated by simple conductometry under different temperatures. The experimental results can be well represented by the proposed regular solution theory and the thermodynamic parameters satisfy the thermodynamic consistency. The deviation from ideal partition is manifested through the effective interaction energy between lipid and surfactant wb, which is O(kT) large. It is found that wb rises as the alkyl chain is decreased for a specified head group. This is attributed to significant mismatch of chain lengths between surfactant and lipid molecules. The partition coefficient K declines with increasing temperature. The energy barrier from bilayer to aqueous phase, Δμ/kT∝ln K, is in the range of 16-26 kJ/mol. As the alkyl chain length is decreased for a given head group, Δμ is lowered by 1.3-1.5 kJ/mol per methylene group. Two independent analyses are employed to confirm this result. Using the thermodynamic parameters determined from experiments, the internal energy, entropy, and free energy of the partition process can be derived. Partition is essentially driven by the internal energy gain. The solubilizing ability, which is represented by the maximum surfactant-lipid ratio in the bilayer, Reb also decreases in accord with the K parameter. It is because the change in temperature influences the surfactant incorporation into the bilayer more than the formation of micelles.

Phase Stable RF-over-fiber Transmission using Heterodyne Interferometry

International Nuclear Information System (INIS)

Wilcox, R.; Byrd, J.M.; Doolittle, L.; Huang, G.; Staples, J.W.

2010-01-01

New scientific applications require phase-stabilized RF distribution to multiple remote locations. These include phased-array radio telescopes and short pulse free electron lasers. RF modulated onto a CW optical carrier and transmitted via fiber is capable of low noise, but commercially available systems aren't long term stable enough for these applications. Typical requirements are for less than 50fs long term temporal stability between receivers, which is 0.05 degrees at 3GHz. Good results have been demonstrated for RF distribution schemes based on transmission of short pulses, but these require specialized free-space optics and high stability mechanical infrastructure. We report a method which uses only standard telecom optical and RF components, and achieves less than 20fs RMS error over 300m of standard single-mode fiber. We demonstrate stable transmission of 3GHz over 300m of fiber with less than 0.017 degree (17fs) RMS phase error. An interferometer measures optical phase delay, providing information to a feed-forward correction of RF phase.

Lightweight Thermally Stable Multi-Meter Aperture Submillimeter Reflectors, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — The objective of the Phase II effort will be an affordable demonstrated full-scale design for a thermally stable multi-meter submillimeter reflector. The Phase I...

Structural Properties and Thermodynamic Stability of Metastable Phases in the Zr-Nb and Ti-V Systems

International Nuclear Information System (INIS)

Aurelio, Gabriela

2003-01-01

The structural properties and relative stability of metastable phases have been studied in the Zr-Nb and Ti-V systems.The first part of this Thesis is connected to a previous work performed in our Group (G. Grad, PhD Thesis, Instituto Balseiro, Argentina, 1999).It presents a phenomenological analysis of the systematics of interatomic distances in the omega (Ω ) and bcc (β) phases of the transition metals, which concerns a parameter entering into Pauling's resonating-valence- bond-theory and the structural and bonding properties of the Ω and β phases.Neutron diffraction experiments in Zr-Nb and Ti-V alloys are reported, aimed at studying possible atomic ordering in the Ω phase and the composition dependence of its interatomic distances.An extensive neutron diffraction study was performed on a series of Zr-Nb and Ti-V alloys quenched from high temperatures, where β is the stable phase.Upon quenching, three metastable structures are formed, viz., the hcp (∝ q ) phase, the Ω q phase, and the untransformed β q phase.The structural properties of these metastable phases were determined as a function of the Nb and V contents to generate a reliable experimental database.With such data, a series of issues are discussed related to the structure, relative stability, and phase relations in the alloys and its constitutive elements.The effect of composition upon the lattice parameters of the metastable β q and Ω q phases was combined in a consistent way with a critical analysis of structural and thermophysical data on the metastable phases of Ti and Zr.The relative stability of the metastable ∝ q , Ω q and β q phases in Zr-Nb alloys, and its evolution towards thermodynamic equilibrium, were studied combining neutron thermodiffraction and analytical electron microscopy techniques.During isothermal heat treatments performed at high temperature, the structural properties of the alloys were determined as a function of temperature, time and composition.A method of

Microcanonical thermodynamics and statistical fragmentation of dissipative systems. The topological structure of the N-body phase space

Science.gov (United States)

Gross, D. H. E.

1997-01-01

This review is addressed to colleagues working in different fields of physics who are interested in the concepts of microcanonical thermodynamics, its relation and contrast to ordinary, canonical or grandcanonical thermodynamics, and to get a first taste of the wide area of new applications of thermodynamical concepts like hot nuclei, hot atomic clusters and gravitating systems. Microcanonical thermodynamics describes how the volume of the N-body phase space depends on the globally conserved quantities like energy, angular momentum, mass, charge, etc. Due to these constraints the microcanonical ensemble can behave quite differently from the conventional, canonical or grandcanonical ensemble in many important physical systems. Microcanonical systems become inhomogeneous at first-order phase transitions, or with rising energy, or with external or internal long-range forces like Coulomb, centrifugal or gravitational forces. Thus, fragmentation of the system into a spatially inhomogeneous distribution of various regions of different densities and/or of different phases is a genuine characteristic of the microcanonical ensemble. In these cases which are realized by the majority of realistic systems in nature, the microcanonical approach is the natural statistical description. We investigate this most fundamental form of thermodynamics in four different nontrivial physical cases: (I) Microcanonical phase transitions of first and second order are studied within the Potts model. The total energy per particle is a nonfluctuating order parameter which controls the phase which the system is in. In contrast to the canonical form the microcanonical ensemble allows to tune the system continuously from one phase to the other through the region of coexisting phases by changing the energy smoothly. The configurations of coexisting phases carry important informations about the nature of the phase transition. This is more remarkable as the canonical ensemble is blind against these

Sigma phase morphologies in cast and aged super duplex stainless steel

International Nuclear Information System (INIS)

Martins, Marcelo; Casteletti, Luiz Carlos

2009-01-01

Solution annealed and water quenched duplex and super duplex stainless steels are thermodynamically metastable systems at room temperature. These systems do not migrate spontaneously to a thermodynamically stable condition because an energy barrier separates the metastable and stable states. However, any heat input they receive, for example through isothermal treatment or through prolonged exposure to a voltaic arc in the welding process, cause them to reach a condition of stable equilibrium which, for super duplex stainless steels, means precipitation of intermetallic and carbide phases. These phases include the sigma phase, which is easily identified from its morphology, and its influence on the material's impact strength. The purpose of this work was to ascertain how 2-hour isothermal heat treatments at 920 deg. C and 980 deg. C affect the microstructure of ASTM A890/A890M GR 6A super duplex stainless steel. The sigma phase morphologies were found to be influenced by these two aging temperatures, with the material showing a predominantly lacy microstructure when heat treated at 920 deg. C and block-shaped when heat treated at 980 deg. C.

Braun-Le Chatelier principle in dissipative thermodynamics

OpenAIRE

Pavelka, Michal; Grmela, Miroslav

2016-01-01

Braun-Le Chatelier principle is a fundamental result of equilibrium thermodynamics, showing how stable equilibrium states shift when external conditions are varied. The principle follows from convexity of thermodynamic potential. Analogously, from convexity of dissipation potential it follows how steady non-equilibrium states shift when thermodynamic forces are varied, which is the extension of the principle to dissipative thermodynamics.

Black hole thermodynamics in Lovelock gravity's rainbow with (A)dS asymptote

Energy Technology Data Exchange (ETDEWEB)

Hendi, Seyed Hossein, E-mail: hendi@shirazu.ac.ir [Physics Department and Biruni Observatory, College of Sciences, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of); Research Institute for Astrophysics and Astronomy of Maragha (RIAAM), P.O. Box 55134-441, Maragha (Iran, Islamic Republic of); Dehghani, Ali, E-mail: ali.dehghani.phys@gmail.com [Physics Department and Biruni Observatory, College of Sciences, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of); Faizal, Mir, E-mail: f2mir@uwaterloo.ca [Irving K. Barber School of Arts and Sciences, University of British Columbia – Okanagan, Kelowna, BC V1V 1V7 (Canada); Department of Physics and Astronomy, University of Lethbridge, Lethbridge, AB T1K 3M4 (Canada)

2017-01-15

In this paper, we combine Lovelock gravity with gravity's rainbow to construct Lovelock gravity's rainbow. Considering the Lovelock gravity's rainbow coupled to linear and also nonlinear electromagnetic gauge fields, we present two new classes of topological black hole solutions. We compute conserved and thermodynamic quantities of these black holes (such as temperature, entropy, electric potential, charge and mass) and show that these quantities satisfy the first law of thermodynamics. In order to study the thermal stability in canonical ensemble, we calculate the heat capacity and determinant of the Hessian matrix and show in what regions there are thermally stable phases for black holes. Also, we discuss the dependence of thermodynamic behavior and thermal stability of black holes on rainbow functions. Finally, we investigate the critical behavior of black holes in the extended phase space and study their interesting properties.

CO2 Capture with Liquid-Liquid Phase Change Solvents: A Thermodynamic Study

DEFF Research Database (Denmark)

Waseem Arshad, Muhammad; Fosbøl, Philip Loldrup; von Solms, Nicolas

2017-01-01

by the quaternary H2O-DEEAMAPA-CO2 system which gives liquid-liquid phase split when reacted with carbon dioxide. A total of 94 model parameters and 6 thermodynamic properties were fitted to approximately 1500 equilibrium and thermal experimental data consisting of pureamine vapor pressure (Pvap), vapor...

Quark–hadron phase structure, thermodynamics, and magnetization of QCD matter

Science.gov (United States)

Nasser Tawfik, Abdel; Magied Diab, Abdel; Hussein, M. T.

2018-05-01

The SU(3) Polyakov linear-sigma model (PLSM) is systematically implemented to characterize the quark-hadron phase structure and to determine various thermodynamic quantities and the magnetization of quantum chromodynamic (QCD) matter. Using mean-field approximation, the dependence of the chiral order parameter on a finite magnetic field is also calculated. Under a wide range of temperatures and magnetic field strengths, various thermodynamic quantities including trace anomaly, speed of sound squared, entropy density, and specific heat are presented, and some magnetic properties are described as well. Where available these results are compared to recent lattice QCD calculations. The temperature dependence of these quantities confirms our previous finding that the transition temperature is reduced with the increase in the magnetic field strength, i.e. QCD matter is characterized by an inverse magnetic catalysis. Furthermore, the temperature dependence of the magnetization showing that QCD matter has paramagnetic properties slightly below and far above the pseudo-critical temperature is confirmed as well. The excellent agreement with recent lattice calculations proves that our QCD-like approach (PLSM) seems to possess the correct degrees of freedom in both the hadronic and partonic phases and describes well the dynamics deriving confined hadrons to deconfined quark-gluon plasma.

Thermodynamic analysis of as-cast and heat-treated microstructures of Mg-Ce-Nd alloys

International Nuclear Information System (INIS)

Groebner, Joachim; Kozlov, Artem; Schmid-Fetzer, Rainer; Easton, Mark A.; Zhu Suming; Gibson, Mark A.; Nie, Jian-Feng

2011-01-01

Alloys based on Mg-rare earth (RE) systems are of increasing technical interest in automotive powertrain applications due to their superior elevated temperature creep resistance. However, there is a deficiency in the literature of phase diagrams of multi-component RE systems that could assist alloy development and composition refinement for enhanced property optimization. The phase relationships in the Mg-rich corner of the Mg-Ce-Nd system have been investigated through the evaluation of selected compositions in the as-cast and heat-treated condition. Consistent thermodynamic CALPHAD-type assessments have also been generated for the Mg-Ce-Nd system. It is shown that this system reveals a significant degree of metastability under technologically significant solidification conditions (i.e. permanent-mould or high-pressure die casting). This is simulated in thermodynamic calculations by suppression of the RE 5 Mg 41 phase and reasonable agreement is found with the as-cast microstructures. After heat treatment these microstructures transform, depending on the alloy composition, into phase assemblies consistent with the calculated stable equilibrium phase diagram. It is the elucidation of such metastable phase formation and the subsequent transformation from the as-cast to the heat-treated state that is a particular strength of the thermodynamic approach and which makes it a powerful tool for alloy development.

Thermodynamic analysis of as-cast and heat-treated microstructures of Mg-Ce-Nd alloys

Energy Technology Data Exchange (ETDEWEB)

Groebner, Joachim; Kozlov, Artem [Institute of Metallurgy, Clausthal University of Technology, Robert-Koch-Str. 42, D-38678 Clausthal-Zellerfeld (Germany); Schmid-Fetzer, Rainer, E-mail: schmid-fetzer@tu-clausthal.de [Institute of Metallurgy, Clausthal University of Technology, Robert-Koch-Str. 42, D-38678 Clausthal-Zellerfeld (Germany); Easton, Mark A.; Zhu Suming [CAST CRC, Department of Materials Engineering, Monash University, Victoria 3800 (Australia); Gibson, Mark A. [CAST CRC, CSIRO Process Science and Engineering, Clayton, Victoria 3169 (Australia); Nie, Jian-Feng [CAST CRC, Department of Materials Engineering, Monash University, Victoria 3800 (Australia)

2011-01-15

Alloys based on Mg-rare earth (RE) systems are of increasing technical interest in automotive powertrain applications due to their superior elevated temperature creep resistance. However, there is a deficiency in the literature of phase diagrams of multi-component RE systems that could assist alloy development and composition refinement for enhanced property optimization. The phase relationships in the Mg-rich corner of the Mg-Ce-Nd system have been investigated through the evaluation of selected compositions in the as-cast and heat-treated condition. Consistent thermodynamic CALPHAD-type assessments have also been generated for the Mg-Ce-Nd system. It is shown that this system reveals a significant degree of metastability under technologically significant solidification conditions (i.e. permanent-mould or high-pressure die casting). This is simulated in thermodynamic calculations by suppression of the RE{sub 5}Mg{sub 41} phase and reasonable agreement is found with the as-cast microstructures. After heat treatment these microstructures transform, depending on the alloy composition, into phase assemblies consistent with the calculated stable equilibrium phase diagram. It is the elucidation of such metastable phase formation and the subsequent transformation from the as-cast to the heat-treated state that is a particular strength of the thermodynamic approach and which makes it a powerful tool for alloy development.

Experimental investigation and thermodynamic calculations of the Ag–Bi–Ga phase diagram

Energy Technology Data Exchange (ETDEWEB)

Minić, Duško, E-mail: dminic65@open.telekom.rs [University in Priština, Faculty of Technical Science, Kos. Mitrovica (Serbia); Premović, Milena [University in Priština, Faculty of Technical Science, Kos. Mitrovica (Serbia); Manasijević, Dragan [University of Belgrade, Technical Faculty, Bor (Serbia); Ćosović, Vladan [University of Belgrade, Institute of Chemistry, Technology and Metallurgy, Belgrade (Serbia); Živković, Dragana [University of Belgrade, Technical Faculty, Bor (Serbia); Marković, Aleksandar [University in Priština, Faculty of Technical Science, Kos. Mitrovica (Serbia)

2015-10-15

Phase diagram of the Ag–Bi–Ga ternary system was investigated using differential thermal analysis (DTA), scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS), and x-ray powder diffraction (XRD) methods. Experimentally obtained results were compared with the results of thermodynamic prediction of phase equilibria based on calculation of phase diagram (CALPHAD) method. Phase transition temperatures of alloys with overall compositions along three selected vertical sections Ag–Bi{sub 50}Ga{sub 50}, Bi–Ag{sub 50}Ga{sub 50} and Ga–Ag{sub 50}Bi{sub 50} were measured by DTA. Liquidus temperatures were experimentally determined and compared with the results of thermodynamic calculation. Identification of coexisting phases in samples equilibrated at 200 °C was carried out using SEM-EDS and XRD methods. Obtained results were compared with the calculated isothermal section of the Ag–Bi–Ga ternary system at corresponding temperature. Calculated liquidus projection and invariant equilibria of the Ag–Bi–Ga ternary system were presented. The obtained values were found to be in a close agreement. - Highlights: • Calculated constitutive binary system based on literature data. • Experimentally determined (DTA) temperatures of phase transformations compared with analytical calculation. • Definition of three vertical sections Ag–Bi{sub 50}Ga{sub 50}, Bi–Ag{sub 50}Ga{sub 50} and Ga–Ag{sub 50}Bi{sub 50}. • Calculated horizontal section at 200 °C, confirmed by experimental SEM-EDS and XRD method. • Calculated liquidus surface projection and determined invariant reaction occurred in ternary Ag–Bi–Ga system.

Relationships between molecular structure and kinetic and thermodynamic controls in lipid systems. Part II: Phase behavior and transformation paths of SSS, PSS and PPS saturated triacylglycerols--effect of chain length mismatch.

Science.gov (United States)

Bouzidi, Laziz; Narine, Suresh S

2012-01-01

The kinetic phase behavior and phase transformation paths of purified tristearoylglycerol (SSS), 3-palmitoyl-1,2-distearoyl-sn-glycerol (PSS) and 1,2-dipalmitoyl-3-stearoyl-sn-glycerol (PPS) were investigated in terms of polymorphism, crystallization and melting. The details of the phase transformation paths were obtained using the heating cycles of two sets of experiments: (a) cooling rate was varied and heating rate fixed and (b) cooling rate was fixed and heating rate varied. Kinetic effects were manifest in all measured properties, underscoring the complexity of the phase transformation paths for each TAG, and the intricate thermodynamics-molecular relationships. For the first time, XRD data obtained for SSS, PSS and PPS TAGs, cooled at rates higher than 0.5°C/min, suggested the formation of a transient structure similar to the so-called α(2)-phase which has been observed in mixed saturated-unsaturated TAGs quenched from the melt. The more stable phases (β' in PSS and PPS, and β in SSS) were only observed for cooling rates lower than 1.0°C/min. The kinetic and thermodynamic differences observed in the crystallization, structure and melting of SSS, PSS and PPS are proposed to be mainly due to the disturbances introduced at the "terrace" level via methyl-end group interactions, i.e., the missing of two or four CH(2) groups compared to SSS. The symmetrical SSS with a relatively flat "terrace" crystallizes preferably in the most stable β-form. Two missing CH(2) groups at the sn-1 position (PSS) introduces enough structural disturbances to promote the relative prevalence and persistence of the β'-phase, and four missing CH(2) groups at the sn-1 and sn-2 positions (PPS) is relatively too large of a disturbance and therefore favors the α-form. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

On thermodynamics of charged AdS black holes in extended phases space via M2-branes background

International Nuclear Information System (INIS)

Chabab, M.; Masmar, K.; El Moumni, H.

2016-01-01

Motivated by a recent work on asymptotically AdS 4 black holes in M-theory, we investigate both thermodynamics and the thermodynamical geometry of Reissner-Nordstrom-AdS black holes from M2-branes. More precisely, we study AdS black holes in AdS 4 x S 7 , with the number of M2-branes interpreted as a thermodynamical variable. In this context, we calculate various thermodynamical quantities including the chemical potential, and examine their phase transitions along with the corresponding stability behaviors. In addition, we also evaluate the thermodynamical curvatures of the Weinhold, Ruppeiner, and Quevedo metrics for M2-branes geometry to study the stability of such a black object. We show that the singularities of these scalar curvature's metrics reproduce similar stability results to those obtained by the phase transition diagram via the heat capacities in different ensembles either when the number of the M2 branes or the charge is held fixed. Also, we note that all results derived in Belhaj et al. (Eur Phys J C 76(2):73, 2016) are recovered in the limit of the vanishing charge. (orig.)

Low temperature thermodynamic investigation of the phase diagram of Sr3Ru2O7

Science.gov (United States)

Sun, D.; Rost, A. W.; Perry, R. S.; Mackenzie, A. P.; Brando, M.

2018-03-01

We studied the phase diagram of Sr3Ru2O7 by means of heat capacity and magnetocaloric effect measurements at temperatures as low as 0.06 K and fields up to 12 T. We confirm the presence of a new quantum critical point at 7.5 T which is characterized by a strong non-Fermi-liquid behavior of the electronic specific heat coefficient Δ C /T ˜-logT over more than a decade in temperature, placing strong constraints on theories of its criticality. In particular logarithmic corrections are found when the dimension d is equal to the dynamic critical exponent z , in contrast to the conclusion of a two-dimensional metamagnetic quantum critical end point, recently proposed. Moreover, we achieved a clear determination of the new second thermodynamic phase adjoining the first one at lower temperatures. Its thermodynamic features differ significantly from those of the dominant phase and characteristics expected of classical equilibrium phase transitions are not observed, indicating fundamental differences in the phase formation.

Thermodynamics of low-temperature phyllosilicates: from a macroscopic perspective towards achieving atomistic simulation

International Nuclear Information System (INIS)

Dubacq, B.

2008-12-01

Phyllosilicates are important minerals in metamorphic petrology as well as in waste storage sites where clays are extensively used. Despite this fact, there is no thermodynamic model allowing to describe and to predict properly the behaviour of clay minerals (for example variation of volume with dehydration) and their phase relations with other minerals in metamorphic conditions. Inversely, the thermodynamic models of phengites are well constrained at high pressure and temperature but do not allow accurate thermo-barometric estimations at temperatures less than about 350 C. In this study, we propose two new thermodynamic models for smectites, illites, mixed-layers illites / smectites and phengites. With these models, it is possible to predict the composition of stable clays at low temperature and to estimate the pressure and temperature of crystallisation of di-octahedral aluminous phyllosilicates. These models take into consideration the hydration state of clay minerals as a function of pressure, temperature and water activity. The thermodynamic properties of solid solutions and hydrated mica-like end-members have been estimated in order to reproduce experimental results of i) clay dehydration, ii) nature of stable phases, iii) calorimetric measurements, as well as known (or estimated with independent methods) pressure-temperature conditions of crystallization of phyllosilicates analyses, from diagenesis conditions to ultra - high - pressure / temperature conditions. Phase diagrams have been computed with these models in simple systems. Conditions of crystallization of phyllosilicates have been estimated on many samples, including electron microprobe compositional maps. We investigated several approaches to estimate thermodynamic properties of minerals. All these methods revealed to be insufficiently accurate to estimate standard enthalpy of formation; calculated enthalpies of formation can not be directly used for thermo-barometric estimations. However, we

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.

First-principles study of the elastic and thermodynamic properties of thorium hydrides at high pressure

Science.gov (United States)

Xiao-Lin, Zhang; Yuan-Yuan, Wu; Xiao-Hong, Shao; Yong, Lu; Ping, Zhang

2016-05-01

The high pressure behaviors of Th4H15 and ThH2 are investigated by using the first-principles calculations based on the density functional theory (DFT). From the energy-volume relations, the bct phase of ThH2 is more stable than the fcc phase at ambient conditions. At high pressure, the bct ThH2 and bcc Th4H15 phases are more brittle than they are at ambient pressure from the calculated elastic constants and the Poisson ratio. The thermodynamic stability of the bct phase ThH2 is determined from the calculated phonon dispersion. In the pressure domain of interest, the phonon dispersions of bcc Th4H15 and bct ThH2 are positive, indicating the dynamical stability of these two phases, while the fcc ThH2 is unstable. The thermodynamic properties including the lattice vibration energy, entropy, and specific heat are predicted for these stable phases. The vibrational free energy decreases with the increase of the temperature, and the entropy and the heat capacity are proportional to the temperature and inversely proportional to the pressure. As the pressure increases, the resistance to the external pressure is strengthened for Th4H15 and ThH2. Project supported by the Long-Term Subsidy Mechanism from the Ministry of Finance and the Ministry of Education of China.

Thermal performance study of form-stable composite phase change material with polyacrylic

Science.gov (United States)

Kee, Shin Yiing; Munusamy, Yamuna; Ong, Kok Seng; Chee, Swee Yong; Sanmuggam, Shimalaa

2017-04-01

Phase change material (PCM) is one of the most popular and widely used as thermal energy storage material because it is able to absorb and release a large amount of latent heat during a phase change process over a narrow temperature range. In this work, the form-stable composite PCM was prepared by blending of PMMA and myristic acid in different weight percentage. PMMA was used as a supporting material while myristic acid was used as PCM. Theoretically, PCM can be encapsulated in the support material after blending. However, a small amount of liquid PCMs can leak out from supporting material due to the volume change in phase change process. Therefore, a form-stable composite PCM with polyacrylic coating was studied. Leakage test was carried out to determine the leakage percentage of the form-stable composite PCM. Fourier transform infrared spectroscopy (FTIR) was used to characterize the chemical compatibility of the form-stable PCM composite while differential scanning calorimetry (DSC) was used to study the melting, freezing point and the latent heat of melting and freezing for the form-stable composite PCM.

Thermodynamics of novel charged dilatonic BTZ black holes

Science.gov (United States)

Dehghani, M.

2017-10-01

In this paper, the three-dimensional Einstein-Maxwell theory in the presence of a dilatonic scalar field has been studied. It has been shown that the dilatonic potential must be considered as the linear combination of two Liouville-type potentials. Two new classes of charged dilatonic BTZ black holes, as the exact solutions to the coupled scalar, vector and tensor field equations, have been obtained and their properties have been studied. The conserved charge and mass of the new black holes have been calculated, making use of the Gauss's law and Abbott-Deser proposal, respectively. Through comparison of the thermodynamical extensive quantities (i.e. temperature and entropy) obtained from both, the geometrical and the thermodynamical methods, the validity of the first law of black hole thermodynamics has been confirmed for both of the new black holes we just obtained. A black hole thermal stability or phase transition analysis has been performed, making use of the canonical ensemble method. Regarding the black hole heat capacity, it has been found that for either of the new black hole solutions there are some specific ranges in such a way that the black holes with the horizon radius in these ranges are locally stable. The points of type one and type two phase transitions have been determined. The black holes, with the horizon radius equal to the transition points are unstable. They undergo type one or type two phase transitions to be stabilized.

Thermodynamic analysis of dust sulphation reactions

Energy Technology Data Exchange (ETDEWEB)

Yang Yongxiang; Jokilaakso, A.

1997-12-31

Sulphation reactions of metal oxides with SO{sub 2} and O. or SO{sub 3} play significant roles in sulphation roasting of sulphide and oxide minerals as well as in desulphurisation process of combustion gases. In metallurgical waste-heat boilers for sulphide smelting, the sulphation of the oxidic flue dust in the atmosphere containing sulphur oxides is an unavoidable process, and the sulphation reactions have to be guided in a controlled way in the proper parts of the gas handling equipment. In this report, some thermodynamic analyses were conducted for the oxide sulphation reactions in relation to sulphide smelting processes. The phase stability of Me-S-O systems especially for oxides - sulphates equilibrium was studied under different thermodynamic conditions of gas compositions and temperatures. The sulphate stability was analysed for an example of gas compositions in the copper flash smelter of Outokumpu Harjavalta Metals Oy, in relation to temperature. In the report, most of the information was from literature. Moreover, a number of thermodynamic computations were carried out with the HSC program, and the constructed phase stability diagrams were compared with those from the literature whenever possible. The maximum temperatures for stable sulphates under normal operating conditions of the waste-heat boilers in sulphide smelting processes were obtained. This report will serve as the basis for the kinetic studies of the sulphation reactions and the sulphation reaction modelling in pyrometallurgical processes. (orig.) SULA 2 Programme. 36 refs.

Predictive calculation of phase formation in Al-rich Al-Zn-Mg-Cu-Sc-Zr alloys using a thermodynamic Mg-alloy database

International Nuclear Information System (INIS)

Groebner, J.; Rokhlin, L.L.; Dobatkina, T.V.; Schmid-Fetzer, R.

2007-01-01

Three series of Al-rich alloys in the system Al-Zn-Mg-Cu-Sc-Zr and the subsystems Al-Zn-Mg-Cu-Sc and Al-Zn-Mg-Sc were studied by thermodynamic calculations. Phase formation was compared with experimental data obtained by DTA and microstructural analysis. Calculated phase diagrams, phase amount charts and enthalpy charts together with non-equilibrium calculations under Scheil conditions reveal significant details of the complex phase formation. This enables consistent and correct interpretation of thermal analysis data. Especially the interpretation of liquidus temperature and primary phase is prone to be wrong without using this tool of computational thermodynamics. All data are predictions from a thermodynamic database developed for Mg-alloys and not a specialized Al-alloy database. That provides support for a reasonable application of this database for advanced Mg-alloys beyond the conventional composition ranges

Predictive calculation of phase formation in Al-rich Al-Zn-Mg-Cu-Sc-Zr alloys using a thermodynamic Mg-alloy database

Energy Technology Data Exchange (ETDEWEB)

Groebner, J. [Institute of Metallurgy, Clausthal University of Technology, Robert-Koch Strasse 42, D-38678 Clausthal-Zellerfeld (Germany); Rokhlin, L.L. [Baikov Institute of Metallurgy and Materials Science, Leninsky prosp. 49, 119991 GSP-1, Moscow (Russian Federation); Dobatkina, T.V. [Baikov Institute of Metallurgy and Materials Science, Leninsky prosp. 49, 119991 GSP-1, Moscow (Russian Federation); Schmid-Fetzer, R. [Institute of Metallurgy, Clausthal University of Technology, Robert-Koch Strasse 42, D-38678 Clausthal-Zellerfeld (Germany)]. E-mail: schmid-fetzer@tu-clausthal.de

2007-05-16

Three series of Al-rich alloys in the system Al-Zn-Mg-Cu-Sc-Zr and the subsystems Al-Zn-Mg-Cu-Sc and Al-Zn-Mg-Sc were studied by thermodynamic calculations. Phase formation was compared with experimental data obtained by DTA and microstructural analysis. Calculated phase diagrams, phase amount charts and enthalpy charts together with non-equilibrium calculations under Scheil conditions reveal significant details of the complex phase formation. This enables consistent and correct interpretation of thermal analysis data. Especially the interpretation of liquidus temperature and primary phase is prone to be wrong without using this tool of computational thermodynamics. All data are predictions from a thermodynamic database developed for Mg-alloys and not a specialized Al-alloy database. That provides support for a reasonable application of this database for advanced Mg-alloys beyond the conventional composition ranges.

Studies on Pidotimod Enantiomers With Chiralpak-IA: Crystal Structure, Thermodynamic Parameters and Molecular Docking.

Science.gov (United States)

Dou, Xiaorui; Su, Xin; Wang, Yue; Chen, Yadong; Shen, Weiyang

2015-11-01

Pidotimod, a synthetic dipeptide, has two chiral centers with biological and immunological activity. Its enantiomers were characterized by x-ray crystallographic analysis. A chiral stationary phase (CSP) Chiralpak-IA based on amylose derivatized with tris-(3, 5-dimethylphenyl carbamate) was used to separate pidotimod enantiomers. The mobile phase was prepared in a ratio of 35:65:0.2 of methyl-tert-butyl-ether and acetonitrile trifluoroaceticacid. In addition, thermodynamics and molecular docking methods were used to explain the enantioseparation mechanism by Chiralpak-IA. Thermodynamic studies were carried out from 10 to 45 °C. In general, both retention and enantioselectivity decreased as the temperature increased. Thermodynamic parameters indicate that the interaction force between the pidotimod enantiomer (4S, 2'R) and IA CSP is stronger and their complex model is more stable. According to GOLD molecular docking simulation, Van der Waals force is the leading cause of pidotimod enantiomers separation by IA CSP. © 2015 Wiley Periodicals, Inc.

Thermodynamics and kinetics of vesicles formation processes.

Science.gov (United States)

Guida, Vincenzo

2010-12-15

Vesicles are hollow aggregates, composed of bilayers of amphiphilic molecules, dispersed into and filled with a liquid solvent. These aggregates can be formed either as equilibrium or as out of equilibrium meta-stable structures and they exhibit a rich variety of different morphologies. The surprising richness of structures, the vast range of industrial applications and the presence of vesicles in a number of biological systems have attracted the interest of numerous researchers and scientists. In this article, we review both the thermodynamics and the kinetics aspects of the phenomena of formation of vesicles. We start presenting the thermodynamics of bilayer membranes formation and deformation, with the aim of deriving the conditions for the existence of equilibrium vesicles. Specifically, we use the results from continuum thermodynamics to discuss the possibility of formation of stable equilibrium vesicles, from both mixed amphiphiles and single component systems. We also link the bilayer membrane properties to the molecular structure of the starting amphiphiles. In the second part of this article, we focus on the dynamics and kinetics of vesiculation. We review the process of vesicles formation both from planar lamellar phase under shear and from isotropic micelles. In order to clarify the physical mechanisms of vesicles formation, we continuously draw a parallel between emulsification and vesiculation processes. Specifically, we compare the experimental results, the driving forces and the relative scaling laws identified for the two processes. Describing the dynamics of vesicles formation, we also discuss why non equilibrium vesicles can be formed by kinetics control and why they are meta-stable. Understanding how to control the properties, the stability and the formation process of vesicles is of fundamental importance for a vast number of industrial applications. Copyright © 2009. Published by Elsevier B.V.

A thermodynamic evaluation of the Fe-Nb system

International Nuclear Information System (INIS)

Srikanth, S.; Petric, A.

1994-01-01

An optimised set of thermodynamic functions consistent with the phase diagram was derived for the Fe-Nb system from information on phase equilibria and thermodynamic data available in the literature. The thermodynamic properties of the intermediate ε (Fe 2 Nb) phase were described using the sublattice model. A Redlich-Kister equation was used to describe the excess thermodynamic functions of the liquid, bcc and fcc phases. For the μ phase, the enthalpy of formation was estimated from Miedema's model. The interaction coefficients were evaluated using an optimisation procedure employing a conjugate gradient method. The phase diagram and the thermodynamic functions calculated from the evaluated parameters are in good agreement with experimental data. (orig.)

Thermodynamic analysis of fuels in gas phase: ethanol, gasoline and ethanol - gasoline predicted by DFT method.

Science.gov (United States)

Neto, A F G; Lopes, F S; Carvalho, E V; Huda, M N; Neto, A M J C; Machado, N T

2015-10-01

This paper presents a theoretical study using density functional theory to calculate thermodynamics properties of major molecules compounds at gas phase of fuels like gasoline, ethanol, and gasoline-ethanol mixture in thermal equilibrium on temperature range up to 1500 K. We simulated a composition of gasoline mixture with ethanol for a thorough study of thermal energy, enthalpy, Gibbs free energy, entropy, heat capacity at constant pressure with respect to temperature in order to study the influence caused by ethanol as an additive to gasoline. We used semi-empirical computational methods as well in order to know the efficiency of other methods to simulate fuels through this methodology. In addition, the ethanol influence through the changes in percentage fractions of chemical energy released in combustion reaction and the variations on thermal properties for autoignition temperatures of fuels was analyzed. We verified how ethanol reduces the chemical energy released by gasoline combustion and how at low temperatures the gas phase fuels in thermal equilibrium have similar thermodynamic behavior. Theoretical results were compared with experimental data, when available, and showed agreement. Graphical Abstract Thermodynamic analysis of fuels in gas phase.

Thermodynamics and stability of flat anti-de Sitter black strings

International Nuclear Information System (INIS)

Chen Si; Schleich, Kristin; Witt, Donald M.

2008-01-01

We examine the thermodynamics and stability of 5-dimensional flat anti-de Sitter (AdS) black strings, locally asymptotically anti-de Sitter spacetimes whose spatial sections are AdS black holes with Ricci flat horizons. We find that there is a phase transition for the flat AdS black string when the AdS soliton string is chosen as the thermal background. We find that this bulk phase transition corresponds to a 4-dimensional flat AdS black hole to AdS soliton phase transition on the boundary Karch-Randall branes. We compute the possibility of a phase transition from a flat AdS black string to a 5-dimensional AdS soliton and show that, though possible for certain thin black strings, the transition to the AdS soliton string is preferred. In contrast to the case of the Schwarzschild-AdS black string, we find that the specific heat of the flat AdS black string is always positive; hence it is thermodynamically stable. We show numerically that both the flat AdS black string and AdS soliton string are free of a Gregory-Laflamme instability for all values of the mass parameter. Therefore thermodynamic stability implies perturbative stability for this spacetime. This may indicate that a generalization of the Gubser-Mitra conjecture, in which the assumption of a translational killing vector is weakened to that of a conformal killing vector of translational form, holds under certain conditions.

Thermodynamics of phase formation and heavy quasiparticles in Sr{sub 3}Ru{sub 2}O{sub 7}

Energy Technology Data Exchange (ETDEWEB)

Rost, Andreas W.; Bruin, Jan A.N.; Tian, Demian; Mackenzie, Andrew P. [SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY169SS (United Kingdom); Grigera, Santiago A. [SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY169SS (United Kingdom); Instituto de Fisica de Liquidos y Sistemas Biologicos, UNLP-CONICET, La Plata 1900 (Argentina); Perry, Robin S. [SUPA, School of Physics, University of Edinburgh, Mayfield Road, Edinburgh EH93JZ (United Kingdom); Raghu, Sri [Department of Physics and Astronomy, Rice University, Houston, Texas, 77005 (United States); Kivelson, Steve A. [Department of Physics, Stanford University, Stanford, California, 94305 (United States)

2012-07-01

The itinerant metamagnet Sr{sub 3}Ru{sub 2}O{sub 7} has motivated a wide range of experimental and theoretical work in recent years because of the discovery of an unusual low temperature phase which is forming in the vicinity of a proposed quantum critical point. A major challenge is the investigation of the thermodynamic properties of both this unusual phase and the fluctuations associated with the quantum critical point. Here we report on new specific heat measurements extending previous work to the wider phase diagram. Our results shed light on two important aspects of the system. First we discuss the entropic details of the formation of heavy quasiparticles as a function of temperature in this compound relevant for a wide class of materials. Secondly we present thermodynamic evidence for the anomalous low temperature phase forming directly out of the critical high temperature phase.

Assessment of thermodynamic properties and phase diagram in the Ag–In–Pd system

Czech Academy of Sciences Publication Activity Database

Zemanová, A.; Semenova, O.; Kroupa, Aleš; Vřešťál, J.; Chandrasekaran, K.; Richter, K. W.; Ipser, H.

2007-01-01

Roč. 15, č. 1 (2007), s. 77-84 ISSN 0966-9795 R&D Projects: GA MŠk(CZ) OC 532.001 Institutional research plan: CEZ:AV0Z20410507 Keywords : phase diagrams * ternary alloy systems * prediction Subject RIV: BJ - Thermodynamics Impact factor: 2.219, year: 2007

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.

Phase Stability in the Mo-Ti-Zr-C System via Thermodynamic Modeling and Diffusion Multiple Validation

Science.gov (United States)

Kar, Sujoy Kumar; Dheeradhada, Voramon S.; Lipkin, Don M.

2013-08-01

Alloys in the Mo-rich corner of the Mo-Ti-Zr-C system have found broad applications in non-oxidizing environments requiring structural integrity well beyond 1273 K (1000 °C). Alloys such as TZM (Mo-0.5Ti-0.08Zr-0.03C by weight %) and TZC (Mo-1.2Ti-0.3Zr-0.1C by weight) owe much of their high temperature strength and microstructural stability to MC and M2C carbide phases. In turn, the stability of the respective carbides and the subsequent mechanical behavior of the alloys are strongly dependent on the alloying additions and thermal history. A CALPHAD-based thermodynamic modeling approach is employed to develop a quaternary thermodynamic database for the Mo-Ti-Zr-C system. The thermodynamic database thus developed is validated with diffusion multiple experiments and the validated database is exercised to elucidate the effects of alloying and thermal history on the phase equilibrium in Mo-rich alloys.

The phase diagram of KNO3-KClO3

International Nuclear Information System (INIS)

Zhang Xuejun; Tian Jun; Xu Kangcheng; Gao Yici

2004-01-01

The binary phase diagram of KNO 3 -KClO 3 is studied by means of differential scanning calorimetry (DSC) and high-temperature X-ray diffraction. The limited solid solutions, K(NO 3 ) 1-x (ClO 3 ) x (0 3 ) 1-x (ClO 3 ) x (0.90 3 -based solid solutions and KClO 3 -based solid solutions phase, respectively. For KNO 3 -based solid solutions, KNO 3 ferroelectric phase can be stable from 423 to 223 K as a result of substituting of NO 3 by ClO 3 -radicals. The temperatures for solidus and liquidus have been determined based on limited solid solutions. Two models, Henrian solution and regular solution theory for KNO 3 -based (α) phase and KClO 3 -based (β) phase, respectively, are employed to reproduce solidus and liquidus of the phase diagram. The results are in good agreement with the DSC data. The thermodynamic properties for α and β solid solutions have been derived from an optimization procedure using the experimental data. The calculated phase diagram and optimized thermodynamic parameters are thermodynamically self-consistent

Thermodynamics of Taub-NUT/bolt black holes in Einstein-Maxwell gravity

International Nuclear Information System (INIS)

Dehghani, M.H.; Khodam-Mohammadi, A.

2006-01-01

First, we construct the Taub-NUT/bolt solutions of (2k+2)-dimensional Einstein-Maxwell gravity, when all the factor spaces of 2k-dimensional base space B have positive curvature. These solutions depend on two extra parameters, other than the mass and the NUT charge. These are electric charge q and electric potential at infinity V. We investigate the existence of Taub-NUT solutions and find that in addition to the two conditions of uncharged NUT solutions, there exist two extra conditions. These two extra conditions come from the regularity of vector potential at r=N and the fact that the horizon at r=N should be the outer horizon of the NUT charged black hole. We find that the NUT solutions in 2k+2 dimensions have no curvature singularity at r=N, when the 2k-dimensional base space is chosen to be CP 2k . For bolt solutions, there exists an upper limit for the NUT parameter which decreases as the potential parameter increases. Second, we study the thermodynamics of these spacetimes. We compute temperature, entropy, charge, electric potential, action and mass of the black hole solutions, and find that these quantities satisfy the first law of thermodynamics. We perform a stability analysis by computing the heat capacity, and show that the NUT solutions are not thermally stable for even k's, while there exists a stable phase for odd k's, which becomes increasingly narrow with increasing dimensionality and wide with increasing V. We also study the phase behavior of the 4 and 6 dimensional bolt solutions in canonical ensemble and find that these solutions have a stable phase, which becomes smaller as V increases

Second order phase transition in thermodynamic geometry and holographic superconductivity in low-energy stringy black holes

Science.gov (United States)

Rizwan, C. L. Ahmed; Vaid, Deepak

2018-05-01

We study holographic superconductivity in low-energy stringy Garfinkle-Horowitz-Strominger (GHS) dilaton black hole background. We finds that superconducting properties are much similar to s-wave superconductors. We show that the second-order phase transition indicated from thermodynamic geometry is not different from superconducting phase transition.

A new 12% chromium steel strengthened by Z-phase precipitates

DEFF Research Database (Denmark)

Liu, Fang; Rashidi, Masoud; Johansson, Lennart

2016-01-01

In order to increase the corrosion resistance and simultaneously maintain the creep resistance of 9-12% Cr steels at 650 degrees C, a new alloy design concept was proposed, using thermodynamically stable Z-phase (CrTaN) precipitates to strengthen the steel. A new trial Z-phase strengthened 12% Cr...

On the thermodynamics of phase transitions in metal hydrides

Science.gov (United States)

di Vita, Andrea

2012-02-01

Metal hydrides are solutions of hydrogen in a metal, where phase transitions may occur depending on temperature, pressure etc. We apply Le Chatelier's principle of thermodynamics to a particular phase transition in TiH x , which can approximately be described as a second-order phase transition. We show that the fluctuations of the order parameter correspond to fluctuations both of the density of H+ ions and of the distance between adjacent H+ ions. Moreover, as the system approaches the transition and the correlation radius increases, we show -with the help of statistical mechanics-that the statistical weight of modes involving a large number of H+ ions (`collective modes') increases sharply, in spite of the fact that the Boltzmann factor of each collective mode is exponentially small. As a result, the interaction of the H+ ions with collective modes makes a tiny suprathermal fraction of the H+ population appear. Our results hold for similar transitions in metal deuterides, too. A violation of an -insofar undisputed-upper bound on hydrogen loading follows.

Thermodynamic determination of fluorite phases of the ULnO4 type

International Nuclear Information System (INIS)

Paula, H.C.B.

1981-12-01

A method for the determination of structure and thermodynamical stability of fluorite phases of the ULnO 4 type is presented. Through the use of a solid body galvanic chain with CaO-doped ZrO 2 working as an oxygen ion conductor solid electrolyte, phase transformation temperatures are determined, as well as solubility enthalpies and entropies for ULnO 4 systems (Ln= Sm, Tb, Er, Ho, Tm, YB). X-ray analyses confirmed the electrochemical measurements. The emf measurement system is checked by using binary oxides with known composition and oxygen partial pressure. A comparison between stabilities of analysed compounds is also presented. (Author) [pt

Solubility data for cement hydrate phases (25oC)

International Nuclear Information System (INIS)

Atkins, M.; Glasser, F.P.; Kindness, A.; Macphee, D.E.

1991-05-01

Solubility measurements were performed on most of the more thermodynamically-stable cement hydrate phases, at 25 o C. The results for each hydrate phase are summarised in the form of datasheets. Solubility properties are discussed, and where possible a K sp value is calculated. The data are compared with the data in the literature. (author)

A Hamiltonian approach to Thermodynamics

Energy Technology Data Exchange (ETDEWEB)

Baldiotti, M.C., E-mail: baldiotti@uel.br [Departamento de Física, Universidade Estadual de Londrina, 86051-990, Londrina-PR (Brazil); Fresneda, R., E-mail: rodrigo.fresneda@ufabc.edu.br [Universidade Federal do ABC, Av. dos Estados 5001, 09210-580, Santo André-SP (Brazil); Molina, C., E-mail: cmolina@usp.br [Escola de Artes, Ciências e Humanidades, Universidade de São Paulo, Av. Arlindo Bettio 1000, CEP 03828-000, São Paulo-SP (Brazil)

2016-10-15

In the present work we develop a strictly Hamiltonian approach to Thermodynamics. A thermodynamic description based on symplectic geometry is introduced, where all thermodynamic processes can be described within the framework of Analytic Mechanics. Our proposal is constructed on top of a usual symplectic manifold, where phase space is even dimensional and one has well-defined Poisson brackets. The main idea is the introduction of an extended phase space where thermodynamic equations of state are realized as constraints. We are then able to apply the canonical transformation toolkit to thermodynamic problems. Throughout this development, Dirac’s theory of constrained systems is extensively used. To illustrate the formalism, we consider paradigmatic examples, namely, the ideal, van der Waals and Clausius gases. - Highlights: • A strictly Hamiltonian approach to Thermodynamics is proposed. • Dirac’s theory of constrained systems is extensively used. • Thermodynamic equations of state are realized as constraints. • Thermodynamic potentials are related by canonical transformations.

A Hamiltonian approach to Thermodynamics

International Nuclear Information System (INIS)

Baldiotti, M.C.; Fresneda, R.; Molina, C.

2016-01-01

In the present work we develop a strictly Hamiltonian approach to Thermodynamics. A thermodynamic description based on symplectic geometry is introduced, where all thermodynamic processes can be described within the framework of Analytic Mechanics. Our proposal is constructed on top of a usual symplectic manifold, where phase space is even dimensional and one has well-defined Poisson brackets. The main idea is the introduction of an extended phase space where thermodynamic equations of state are realized as constraints. We are then able to apply the canonical transformation toolkit to thermodynamic problems. Throughout this development, Dirac’s theory of constrained systems is extensively used. To illustrate the formalism, we consider paradigmatic examples, namely, the ideal, van der Waals and Clausius gases. - Highlights: • A strictly Hamiltonian approach to Thermodynamics is proposed. • Dirac’s theory of constrained systems is extensively used. • Thermodynamic equations of state are realized as constraints. • Thermodynamic potentials are related by canonical transformations.

Phase behaviour of the symmetric binary mixture from thermodynamic perturbation theory.

Science.gov (United States)

Dorsaz, N; Foffi, G

2010-03-17

We study the phase behaviour of symmetric binary mixtures of hard core Yukawa (HCY) particles via thermodynamic perturbation theory (TPT). We show that all the topologies of phase diagram reported for the symmetric binary mixtures are correctly reproduced within the TPT approach. In a second step we use the capability of TPT to be straightforwardly extended to mixtures that are nonsymmetric in size. Starting from mixtures that belong to the different topologies of symmetric binary mixtures we investigate the effect on the phase behaviour when an asymmetry in the diameters of the two components is introduced. Interestingly, when the energy of interaction between unlike particles is weaker than the interaction between like particles, the propensity for the solution to demix is found to increase strongly with size asymmetry.

Urea-temperature phase diagrams capture the thermodynamics of denatured state expansion that accompany protein unfolding

Science.gov (United States)

Tischer, Alexander; Auton, Matthew

2013-01-01

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

Evidence of a stable binary CdCa quasicrystalline phase

DEFF Research Database (Denmark)

Jiang, Jianzhong; Jensen, C.H.; Rasmussen, A.R.

2001-01-01

Quasicrystals with a primitive icosahedral structure and a quasilattice constant of 5.1215 Angstrom have been synthesized in a binary Cd-Ca system. The thermal stability of the quasicrystal has been investigated by in situ high-temperature x-ray powder diffraction using synchrotron radiation. It ....... It is demonstrated that the binary CdCa quasicrystal is thermodynamic stable up to its melting temperature. The linear thermal expansion coefficient of the quasicrystal is 2.765x10(-5) K-1. (C) 2001 American Institute of Physics.......Quasicrystals with a primitive icosahedral structure and a quasilattice constant of 5.1215 Angstrom have been synthesized in a binary Cd-Ca system. The thermal stability of the quasicrystal has been investigated by in situ high-temperature x-ray powder diffraction using synchrotron radiation...

Thermodynamics for scientists and engineers

International Nuclear Information System (INIS)

Lim, Gyeong Hui

2011-02-01

This book deals with thermodynamics for scientists and engineers. It consists of 11 chapters, which are concept and background of thermodynamics, the first law of thermodynamics, the second law of thermodynamics and entropy, mathematics related thermodynamics, properties of thermodynamics on pure material, equilibrium, stability of thermodynamics, the basic of compound, phase equilibrium of compound, excess gibbs energy model of compound and activity coefficient model and chemical equilibrium. It has four appendixes on properties of pure materials and thermal mass.

Analytical description of thermodynamic properties of steam, water and the phase interface for use in CFD

OpenAIRE

Hrubý Jan; Duška Michal

2014-01-01

We present a system of analytical equations for computation of all thermodynamic properties of dry steam and liquid water (undesaturated, saturated and metastable supersaturated) and properties of the liquid-vapor phase interface. The form of the equations is such that it enables computation of all thermodynamic properties for independent variables directly related to the balanced quantities - total mass, liquid mass, energy, momenta. This makes it suitable for the solvers of fluid dynamics e...

Thermodynamic characterization of lithium monosilicide (LiSi) by means of calorimetry and DFT-calculations

Energy Technology Data Exchange (ETDEWEB)

Taubert, Franziska; Seidel, Juergen; Huettl, Regina; Mertens, Florian [TU Bergakademie Freiberg (Germany). Inst. of Physical Chemistry; Schwalbe, Sebastian; Gruber, Thomas; Kortus, Jens [TU Bergakademie Freiberg (Germany). Inst. of Theoretical Chemistry; Janot, Raphael [Univ. de Picardie Jules Verne UMR 7314 CNRS, Amiens (France). Lab. de Reactivity et Chimie des Solides; Bobnar, Matej [Max-Planck-Institute for Chemical Physics of Solids, Dresden (Germany); Gumeniuk, Roman [TU Bergakademie Freiberg (Germany). Inst. of Experimental Physics

2017-11-15

In this work we summarize a symbiotic approach to combine experimental and theoretical investigations for the derivation of high quality thermodynamic data for the description of potential lithium ion battery materials. The methodology of this concept was demonstrated in detail by exploring and describing the properties of the lithium monosilicide phase LiSi. The procedures were also applied in a series of investigations to all major Li{sub x}Si{sub y}-phases which will be reviewed briefly. Regarding the LiSi phase, the measured and calculated isobaric heat capacity, which may enable further thermodynamic investigations (e.g. with CALPHAD method) of the phase diagram of the Li-Si-system is presented. The heat capacity of the stable phase LiSi was measured as a function of temperature in a range from (2 to 673) K and compared with corresponding ab-initio and molecular dynamic calculations resulting in values for absolute entropies. The heat of formation of the system was determined in an unconventional manner via hydrogenation experiments.

Thermodynamic optimization of the Cu-Nd system

International Nuclear Information System (INIS)

Wang Peisheng; Zhou Liangcai; Du Yong; Xu Honghui; Liu Shuhong; Chen Li; Ouyang Yifang

2011-01-01

Research highlights: → The enthalpies of formation of the compounds Cu 6 Nd, Cu 5 Nd, Cu 2 Nd and αCuNd were calculated using DFT. → The thermodynamic constraints to eliminate the artificial phase relations were imposed during the thermodynamic optimization procedure. → The Cu-Nd system was optimized under the thermodynamic constraints. - Abstract: The thermodynamic constraints to eliminate artificial phase relations were introduced with the Cu-Nd system as an example. The enthalpies of formation of the compounds Cu 6 Nd, Cu 5 Nd, Cu 2 Nd and αCuNd are calculated using density functional theory. Taking into account all the experimental data and the first-principles calculated enthalpies of formation of these compounds, the thermodynamic optimization of the Cu-Nd system was performed under the proposed thermodynamic constraints. It is demonstrated that the thermodynamic constraints are critical to obtain a set of thermodynamic parameters for the Cu-Nd system, which can avoid the appearance of all the artificial phase relations.

The thermodynamics of protein folding: a critique of widely used quasi-thermodynamic interpretations and a restatement based on the Gibbs-Duhem relation and consistent with the Phase Rule.

Science.gov (United States)

Pethica, Brian A

2010-07-21

Interpretations of data in the extensive literature on the unfolding of proteins in aqueous solution follow a variety of methods involving assumptions leading to estimates of thermodynamic quantities associated with the unfolding transition. Inconsistencies and thermodynamic errors in these methods are identified. Estimates of standard molar free energies and enthalpies of unfolding using incompletely defined equilibrium constants and the van't Hoff relation are unsound, and typically contradict model-free interpretation of the data. A widely used routine for estimating the change in heat capacity associated with unfolding based on changes in the unfolding temperature and enthalpy co-induced by addition of denaturant or protective additives is thermodynamically incorrect by neglect of the Phase Rule. Many models and simulations predicting thermodynamic measures of unfolding are presently making comparisons with insecure quantities derived by incorrect thermodynamic analyses of experimental data. Analysis of unfolding via the Gibbs-Duhem equation with the correct Phase Rule constraints avoids the assumptions associated with incomplete equilibrium constants and misuse of the van't Hoff relation, and applies equally to positive, negative, sitewise or diffuse solute binding to the protein. The method gives the necessary relations between the thermodynamic parameters for thermal and isothermal unfolding and is developed for the case of two-state unfolding. The differences in binding of denaturants or stabilizers to the folded and unfolded forms of the protein are identified as major determinants of the unfolding process. The Phase Rule requires the temperature and enthalpy of unfolding to depend generally on the protein concentration. The available evidence bears out this expectation for thermal unfolding, indicating that protein-protein interactions influence folding. A parallel dependence of the denaturant concentrations for isothermal unfolding on the protein

Assessment of the thermodynamic properties and phase diagram of the Bi-Pd system

Czech Academy of Sciences Publication Activity Database

Vřešťál, Jan; Pinkas, J.; Watson, A.; Scott, A.; Houserová, Jana; Kroupa, Aleš

2006-01-01

Roč. 30, č. 1 (2006), s. 14-17 ISSN 0364-5916 R&D Projects: GA MŠk OC 531.001; GA MŠk OC 531.002 Institutional research plan: CEZ:AV0Z20410507 Keywords : phase diagram * ab initio calculations * calorimetry Subject RIV: BJ - Thermodynamics Impact factor: 1.432, year: 2006

Z-phase in 9-12% Cr Steels

DEFF Research Database (Denmark)

Danielsen, Hilmar; Hald, John

2004-01-01

The complex nitride Z-phase, Cr(V,Nb)N, has recently been identified as a major cause for premature breakdown in creep strength of a number of new 9-12%Cr martensitic steels. A thermodynamic model of the Z-phase has been created based on the Thermo-Calc software. The model predicts the Z-phase to......The complex nitride Z-phase, Cr(V,Nb)N, has recently been identified as a major cause for premature breakdown in creep strength of a number of new 9-12%Cr martensitic steels. A thermodynamic model of the Z-phase has been created based on the Thermo-Calc software. The model predicts the Z......-phase to be stable in all of the new 9-12%Cr martensitic steels. This has generally been confirmed by the performed experiments. Z-phase precipitation seems to be a kinetic problem, and drivning force calculations using Thermo-Calc with the developed model have been used to predict steel compositions, which...

Thermodynamic assessment of the Cu–Fe–Ni system

International Nuclear Information System (INIS)

Dreval, Liya A.; Turchanin, Mikhail A.; Agraval, Pavel G.

2014-01-01

Highlights: • The thermodynamic description of the Cu–Fe–Ni system has been updated. • The new experimental data have been used to refine thermodynamic model of the system. • The four-sublattice model has been adopted to predict the equilibria involving the ordered L1 2 phase. • A significant improvement in comparison with the previous assessments has been achieved. • The liquidus and solidus projections have been presented. -- Abstract: The thermodynamic description of the Cu–Fe–Ni system has been updated considering the newly available experimental data, as well as compatibility of the present modeling with those used for the Cu and Fe systems. All of the experimental data available in the literature have been critically reviewed, and the inconsistent information has been excluded. The thermodynamic parameters have been evaluated in order to properly describe the thermodynamic properties of the liquid phase and miscibility gap in the solid state. A significant improvement in comparison with the previous thermodynamic descriptions has been achieved. Additionally, for the ordered L1 2 phase the four-sublattice model has been adopted to predict the ternary phase equilibria involving this phase. A set of thermodynamic parameters for the phases is given

Black hole chemistry: thermodynamics with Lambda

International Nuclear Information System (INIS)

Kubizňák, David; Mann, Robert B; Teo, Mae

2017-01-01

We review recent developments on the thermodynamics of black holes in extended phase space, where the cosmological constant is interpreted as thermodynamic pressure and treated as a thermodynamic variable in its own right. In this approach, the mass of the black hole is no longer regarded as internal energy, rather it is identified with the chemical enthalpy. This leads to an extended dictionary for black hole thermodynamic quantities; in particular a notion of thermodynamic volume emerges for a given black hole spacetime. This volume is conjectured to satisfy the reverse isoperimetric inequality—an inequality imposing a bound on the amount of entropy black hole can carry for a fixed thermodynamic volume. New thermodynamic phase transitions naturally emerge from these identifications. Namely, we show that black holes can be understood from the viewpoint of chemistry, in terms of concepts such as Van der Waals fluids, reentrant phase transitions, and triple points. We also review the recent attempts at extending the AdS/CFT dictionary in this setting, discuss the connections with horizon thermodynamics, applications to Lifshitz spacetimes, and outline possible future directions in this field. (topical review)

Thermodynamic modeling of liquid–liquid phase change solvents for CO2 capture

DEFF Research Database (Denmark)

Waseem Arshad, Muhammad; von Solms, Nicolas; Thomsen, Kaj

2016-01-01

A thermodynamic model based on Extended UNIQUAC framework has been developed in this work for the de-mixing liquid–liquid phase change solvents, DEEA (2-(diethylamino)ethanol) and MAPA (3-(methylamino)propylamine). Parameter estimation was performed for two ternary systems, H2O-DEEA-CO2 and H2O......-MAPA-CO2, and a quaternary system, H2O-DEEA-MAPA-CO2 (phase change system), by using different types of experimental data (equilibrium and thermal) consisting of pure amine vapor pressure, vapor-liquid equilibrium, solid-liquid equilibrium, liquid–liquid equilibrium, excess enthalpy, and heat of absorption...

Thermodynamic study of selected monoterpenes II

International Nuclear Information System (INIS)

Štejfa, Vojtěch; Fulem, Michal; Růžička, Květoslav; Červinka, Ctirad

2014-01-01

Highlights: • (−)-Borneol, (−)-camphor, (±)-camphene, and (+)-fenchone were studied. • New thermodynamic data were measured and calculated. • Most of thermodynamic data are reported for the first time. - Abstract: A thermodynamic study of selected monoterpenes, (−)-borneol, (−)-camphor, (±)-camphene, and (+)-fenchone is presented in this work. The vapor pressure measurements were performed using the static method over the environmentally important temperature range from (238 to 308) K. Heat capacities of condensed phases were measured by Tian–Calvet calorimetry in the temperature interval from (258 to 355) K. The phase behavior was investigated by differential scanning calorimetry (DSC) from subambient temperatures up to the fusion temperatures. The thermodynamic properties in the ideal-gas state were calculated by combining statistical thermodynamic and density functional theory (DFT) calculations. Calculated ideal-gas heat capacities and experimental data for vapor pressures and condensed phase heat capacities were treated simultaneously to obtain a consistent thermodynamic description

Experimental determination and thermodynamic modeling of phase equilibrium and protein partitioning in aqueous two-phase systems containing biodegradable salts

International Nuclear Information System (INIS)

Perez, Brenda; Malpiedi, Luciana Pellegrini; Tubío, Gisela; Nerli, Bibiana; Alcântara Pessôa Filho, Pedro de

2013-01-01

Highlights: ► Binodal data of systems (water + polyethyleneglycol + sodium) succinate are reported. ► Pitzer model describes the phase equilibrium of systems formed by polyethyleneglycol and biodegradable salts satisfactorily. ► This simple thermodynamic framework was able to predict the partitioning behaviour of model proteins acceptably well. - Abstract: Phase diagrams of sustainable aqueous two-phase systems (ATPSs) formed by polyethyleneglycols (PEGs) of different average molar masses (4000, 6000, and 8000) and sodium succinate are reported in this work. Partition coefficients (Kps) of seven model proteins: bovine serum albumin, catalase, beta-lactoglobulin, alpha-amylase, lysozyme, pepsin, urease and trypsin were experimentally determined in these systems and in ATPSs formed by the former PEGs and other biodegradable sodium salts: citrate and tartrate. An extension of Pitzer model comprising long and short-range term contributions to the excess Gibbs free energy was used to describe the (liquid + liquid) equilibrium. Comparison between experimental and calculated tie line data showed mean deviations always lower than 3%, thus indicating a good correlation. The partition coefficients were modeled by using the same thermodynamic approach. Predicted and experimental partition coefficients correlated quite successfully. Mean deviations were found to be lower than the experimental uncertainty for most of the assayed proteins.

Thermodynamic analysis of 6xxx series Al alloys: Phase fraction diagrams

Directory of Open Access Journals (Sweden)

Cui S.

2018-01-01

Full Text Available Microstructural evolution of 6xxx Al alloys during various metallurgical processes was analyzed using accurate thermodynamic database. Phase fractions of all the possible precipitate phases which can form in the as-cast and equilibrium states of the Al-Mg-Si-Cu-Fe-Mn-Cr alloys were calculated over the technically useful composition range. The influence of minor elements such as Cu, Fe, Mn, and Cr on the amount of each type of precipitate in the as-cast and equilibrium conditions were analyzed. Phase fraction diagrams at 500 °C were mapped in the composition range of 0-1.1 wt.% Mg and 0-0.7 wt.% Si to investigate the as-homogenized microstructure. In addition, phase fraction diagram of Mg2Si at 177 °C was mapped to understand the microstructure after final annealing of 6xxx Al alloy. Based on the calculated diagrams, the design strategy of 6xxx Al alloy to produce highest strength due to Mg2Si is discussed.

Thermodynamic properties of hydrated cement phases: C-S-H, C-A-S-H and M-S-H

International Nuclear Information System (INIS)

Roosz, Cedric

2016-01-01

Concrete is one of the most widely used building materials in the world. Durability, mechanical and chemical properties have made it a material of choice in storage concepts proposed by the French National Agency for Radioactive Waste Management (Andra), including the achievement of retaining structures, cell plugs, massive supports or conditioning waste. The study of the stability of the constituent phases of cementitious materials is needed in view of the planned quantities and the durability of the structures, and must consider (i) temperature ranges suitable for cement matrices containment in contact with exothermic waste (25-80 deg. C), and (ii) a representative time scale of the lifetime of the storage. The Andra ThermoChimie project therefore aims to develop a consistent thermodynamic database, to model the chemical evolution of cement materials in the environment of radioactive waste. However, in the present state, the database offers only thermodynamic data of cementitious crystalline phases, as well as a limited data set of three different chemical compositions for nano-crystalline C-S-H. This does not allow to reproduce the degradation of cementitious materials, or model the degradation of the new formulations, such as 'Low pH' concretes. The objective is therefore to acquire a thermodynamic complementary data set on phases such as C-S-H (Calcium Silicate Hydrates) C-A-S-H (Calcium Aluminate Silicate Hydrates) and M-S-H (Magnesium Silicate Hydrates), to complete the ThermoChimie database. This study is based on experimental, analytical and digital work, in order to obtain a set of thermodynamic data (Δ f G 0 , Δ f H 0 , Cp(T), S 0 ) sufficiently representative of the chemical variability of these phases. Finally, this set of data allows the development of a thermodynamic predictive model in extended spaces of compositions and temperatures. Development of this predictive model requires (i) The acquisition of thermodynamic properties on

A route to possible civil engineering materials: the case of high-pressure phases of lime.

Science.gov (United States)

Bouibes, A; Zaoui, A

2015-07-23

Lime system has a chemical composition CaO, which is known as thermodynamically stable. The purpose here is to explore further possible phases under pressure, by means of variable-composition ab initio evolutionary algorithm. The present investigation shows surprisingly new stable compounds of lime. At ambient pressure we predict, in addition to CaO, CaO2 as new thermodynamically stable compound. The latter goes through two phases transition from C2/c space group structure to Pna21 at 1.5 GPa, and Pna21 space group structure to I4/mcm at 23.4 GPa. Under increasing pressure, further compounds such as CaO3 become the most stable and stabilize in P-421m space group structure above 65 GPa. For the necessary knowledge of the new predicted compounds, we have computed their mechanical and electronic properties in order to show and to explain the main reasons leading to the structural changes.

Thermodynamically controlled crystallization of glucose pentaacetates from amorphous phase

Energy Technology Data Exchange (ETDEWEB)

Wlodarczyk, P., E-mail: patrykw@imn.gliwice.pl; Hawelek, L.; Hudecki, A.; Kolano-Burian, A. [Institute of Non-Ferrous Metals, ul. Sowinskiego 5, 44-100 Gliwice (Poland); Wlodarczyk, A. [Department of Animal Histology and Embryology, University of Silesia, ul. Bankowa 9, 40-007 Katowice (Poland)

2016-08-15

The α and β glucose pentaacetates are known sugar derivatives, which can be potentially used as stabilizers of amorphous phase of active ingredients of drugs (API). In the present work, crystallization behavior of equimolar mixture of α and β form in comparison to both pure anomers is revealed. It was shown that despite the same molecular interactions and similar molecular dynamics, crystallization from amorphous phase is significantly suppressed in equimolar mixture. Time dependent X-ray diffraction studies confirmed higher stability of the quenched amorphous equimolar mixture. Its tendency to crystallization is about 10 times lower than for pure anomers. Calorimetric studies revealed that the α and β anomers don’t form solid solutions and have eutectic point for x{sub α} = 0.625. Suppressed crystallization tendency in the mixture is probably caused by the altered thermodynamics of the system. The factors such as difference of free energy between crystalline and amorphous state or altered configurational entropy are probably responsible for the inhibitory effect.

Thermal study on the impurity effect on thermodynamic stability of the glacial phase in triphenyl phosphite-triphenyl phosphate system

International Nuclear Information System (INIS)

Tanabe, Ikue; Takeda, Kiyoshi; Murata, Katsuo

2005-01-01

To investigate the impurity effect on thermodynamic stability of the glacial phase, an apparently amorphous metastable phase observed in triphenyl phosphite (TPP), the differential scanning calorimetry (DSC) was carried out in the temperature range 120-350 K for binary mixtures between TPP and triphenyl phosphate (TPPO). Heating up from the glassy liquid, supercooled liquid phase transformed into glacial phase below the crystallization temperature for all the samples with x < 0.2, where x denotes the mole fraction of TPPO. Both transformation temperatures from liquid to glacial and from glacial to crystal increased and temperature range that glacial phase appears narrowed with the content of TPPO. The peak intensity of exothermic effect due to the transformation from liquid to glacial becomes larger whereas that from glacial to crystal reduced. The kinetic and thermodynamic stabilities were discussed for liquid and glacial phases based on the DSC results

Thermal study on the impurity effect on thermodynamic stability of the glacial phase in triphenyl phosphite-triphenyl phosphate system

Energy Technology Data Exchange (ETDEWEB)

Tanabe, Ikue [Department of Chemistry, Naruto University of Education, Naruto, Tokushima 772-8502 (Japan); Takeda, Kiyoshi [Department of Chemistry, Naruto University of Education, Naruto, Tokushima 772-8502 (Japan)]. E-mail: takeda@naruto-u.ac.jp; Murata, Katsuo [Department of Chemistry, Naruto University of Education, Naruto, Tokushima 772-8502 (Japan)

2005-06-15

To investigate the impurity effect on thermodynamic stability of the glacial phase, an apparently amorphous metastable phase observed in triphenyl phosphite (TPP), the differential scanning calorimetry (DSC) was carried out in the temperature range 120-350 K for binary mixtures between TPP and triphenyl phosphate (TPPO). Heating up from the glassy liquid, supercooled liquid phase transformed into glacial phase below the crystallization temperature for all the samples with x < 0.2, where x denotes the mole fraction of TPPO. Both transformation temperatures from liquid to glacial and from glacial to crystal increased and temperature range that glacial phase appears narrowed with the content of TPPO. The peak intensity of exothermic effect due to the transformation from liquid to glacial becomes larger whereas that from glacial to crystal reduced. The kinetic and thermodynamic stabilities were discussed for liquid and glacial phases based on the DSC results.

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

THERMODYNAMIC MODEL AND VISCOSITY OF SELECTED ZIRCONIA CONTAINING SILICATE GLASSES

Directory of Open Access Journals (Sweden)

MÁRIA CHROMČÍKOVÁ

2013-03-01

Full Text Available The compositional dependence of viscosity, and viscous flow activation energy of glasses with composition xNa2O∙(15-x K2O∙yCaO∙(10-yZnO∙zZrO2∙(75-zSiO2 (x = 0, 7.5, 15; y = 0, 5, 10; z = 0, 1, 3, 5, 7 was analyzed. The studied glasses were described by the thermodynamic model of Shakhmatkin and Vedishcheva considering the glass as an equilibrium ideal solution of species with stoichiometry given by the composition of stable crystalline phases of respective glass forming system. Viscosity-composition relationships were described by the regression approach considering the viscous flow activation energy and the particular isokome temperature as multilinear function of equilibrium molar amounts of system components. The classical approach where the mole fractions of individual oxides are considered as independent variables was compared with the thermodynamic model. On the basis of statistical analysis there was proved that the thermodynamic model is able to describe the composition property relationships with higher reliability. Moreover, due its better physical justification, thermodynamic model can be even used for predictive purposes.

Numerical tests of the electroweak phase transition and thermodynamics of the electroweak plasma

CERN Document Server

Csikor, Ferenc; Hein, J; Jaster, A; Montvay, István

1996-01-01

The finite temperature phase transition in the SU(2) Higgs model at a Higgs boson mass M_H \\simeq 34 GeV is studied in numerical simulations on four-dimensional lattices with time-like extensions up to L_t=5. The effects of the finite volume and finite lattice spacing on masses and couplings are studied in detail. The errors due to uncertainties in the critical hopping parameter are estimated. The thermodynamics of the electroweak plasma near the phase transition is investigated by determining the relation between energy density and pressure.

Modeling thermodynamics of Fe-N phases

DEFF Research Database (Denmark)

Pekelharing, Marjon I.; Böttger, Amarante; Somers, Marcel A. J.

1999-01-01

In the present work homogeneous epsilon-nitride powders prepared at 723 K, having nitrogen contents ranging from 26.1 at. % N (z=0.29) to 31.1 at.% N (z=0.10), were investigated with X-ray diffraction (XRD) and Mössbauer spectroscopy. A thermodynamic model accounting for the two possible configur......In the present work homogeneous epsilon-nitride powders prepared at 723 K, having nitrogen contents ranging from 26.1 at. % N (z=0.29) to 31.1 at.% N (z=0.10), were investigated with X-ray diffraction (XRD) and Mössbauer spectroscopy. A thermodynamic model accounting for the two possible...

First-principles study of lattice dynamics, structural phase transition, and thermodynamic properties of barium titanate

Energy Technology Data Exchange (ETDEWEB)

Zhang, Huai-Yong; Zhao, Ying-Qin; Lu, Qing [Sichuan Univ., Chengdu (China). Inst. of Atomic and Molecular Physics; Zeng, Zhao-Yi [Chongqing Normal Univ. (China). College of Physics and Electronic Engineering; Chinese Academy of Engineering Physics, Mianyang (China). National Key Laboratory for Shock Wave and Detonation Physics Research; Cheng, Yan [Sichuan Univ., Chengdu (China). Inst. of Atomic and Molecular Physics; Sichuan Univ., Chengdu (China). Key Laboratory of High Energy Density Physics and Technology of Ministry of Education

2016-11-01

Lattice dynamics, structural phase transition, and the thermodynamic properties of barium titanate (BaTiO{sub 3}) are investigated by using first-principles calculations within the density functional theory (DFT). It is found that the GGA-WC exchange-correlation functional can produce better results. The imaginary frequencies that indicate structural instability are observed for the cubic, tetragonal, and orthorhombic phases of BaTiO{sub 3} and no imaginary frequencies emerge in the rhombohedral phase. By examining the partial phonon density of states (PDOSs), we find that the main contribution to the imaginary frequencies is the distortions of the perovskite cage (Ti-O). On the basis of the site-symmetry consideration and group theory, we give the comparative phonon symmetry analysis in four phases, which is useful to analyze the role of different atomic displacements in the vibrational modes of different symmetry. The calculated optical phonon frequencies at Γ point for the four phases are in good agreement with other theoretical and experimental data. The pressure-induced phase transition of BaTiO{sub 3} among four phases and the thermodynamic properties of BaTiO{sub 3} in rhombohedral phase have been investigated within the quasi-harmonic approximation (QHA). The sequence of the pressure-induced phase transition is rhombohedral → orthorhombic → tetragonal → cubic, and the corresponding transition pressure is 5.17, 5.92, 6.65 GPa, respectively. At zero pressure, the thermal expansion coefficient α{sub V}, heat capacity C{sub V}, Grueneisen parameter γ, and bulk modulus B of the rhombohedral phase BaTiO{sub 3} are estimated from 0 K to 200 K.

Thermodynamic properties of xanthone: Heat capacities, phase-transition properties, and thermodynamic-consistency analyses using computational results

International Nuclear Information System (INIS)

Chirico, Robert D.; Kazakov, Andrei F.

2015-01-01

Highlights: • Heat capacities were measured for the temperature range (5 to 520) K. • The enthalpy of combustion was measured and the enthalpy of formation was derived. • Thermodynamic-consistency analysis resolved inconsistencies in literature enthalpies of sublimation. • An inconsistency in literature enthalpies of combustion was resolved. • Application of computational chemistry in consistency analysis was demonstrated successfully. - Abstract: Heat capacities and phase-transition properties for xanthone (IUPAC name 9H-xanthen-9-one and Chemical Abstracts registry number [90-47-1]) are reported for the temperature range 5 < T/K < 524. Statistical calculations were performed and thermodynamic properties for the ideal gas were derived based on molecular geometry optimization and vibrational frequencies calculated at the B3LYP/6-31+G(d,p) level of theory. These results are combined with sublimation pressures from the literature to allow critical evaluation of inconsistent enthalpies of sublimation for xanthone, also reported in the literature. Literature values for the enthalpy of combustion of xanthone are re-assessed, a revision is recommended for one result, and a new value for the enthalpy of formation of the ideal gas is derived. Comparisons with thermophysical properties reported in the literature are made for all other reported and derived properties, where possible

Vaporization thermodynamics of Pd-rich intermediate phases in the Pd–Yb system

Energy Technology Data Exchange (ETDEWEB)

Ciccioli, A., E-mail: andrea.ciccioli@uniroma1.it [Dipartimento di Chimica, Sapienza Università di Roma, p.le Aldo Moro 5, 00185 Roma (Italy); Balducci, G.; Gigli, G. [Dipartimento di Chimica, Sapienza Università di Roma, p.le Aldo Moro 5, 00185 Roma (Italy); Provino, A. [Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Genova, via Dodecaneso 31, 16146 Genova (Italy); Istituto SPIN-CNR, Corso Perrone 24, 16152 Genova (Italy); Palenzona, A. [Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Genova, via Dodecaneso 31, 16146 Genova (Italy); Manfrinetti, P. [Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Genova, via Dodecaneso 31, 16146 Genova (Italy); Istituto SPIN-CNR, Corso Perrone 24, 16152 Genova (Italy)

2016-02-20

Highlights: • Vaporization equilibria of Pd–Yb intermediate phases investigated by effusion techniques. • Heats of formation of Pd–Yb compounds determined from decomposition/atomization enthalpies. • Phase diagram of the Pd–Yb system re-drawn. • Influence of the Yb valence state on the thermodynamic properties observed. - Abstract: The vaporization thermodynamics of several intermediate phases in the Pd–Yb system was investigated by means of vaporization experiments performed under Knudsen conditions (KEML, Knudsen Effusion Mass Loss). The following thermal decomposition processes were studied in the overall temperature range 819–1240 K and their enthalpy changes determined: 4 PdYb(s) = Pd{sub 4}Yb{sub 3}(s) + Yb(g); 5/3 Pd{sub 4}Yb{sub 3}(s) = 4/3 Pd{sub 5}Yb{sub 3}(s) + Yb(g); 21/13 Pd{sub 5}Yb{sub 3}(s) = 5/13 Pd{sub 21}Yb{sub 10}(s) + Yb(g); 1/3 Pd{sub 21}Yb{sub 10}(s) = 21/9 Pd{sub 3}Yb(s) + Yb(g). Additional measurements were performed by KEMS (Knudsen Effusion Mass Spectrometry) on a Pd-rich two-phase sample, which allowed to detect both Yb(g) and Pd(g) in the vapor phase and to determine the atomization enthalpy of the Pd{sub 3}Yb phase (Pd-rich composition boundary, Pd{sub 3.08}Yb{sub 0.92}): Pd{sub 3.08}Yb{sub 0.92}(s) = 0.92 Yb(g) + 3.08 Pd(g). The enthalpy of formation of this compound was thereafter determined as −68 ± 2 kJ/mol at. and, by combining this value with the decomposition enthalpies derived by KEML, the enthalpies of formation of the studied Pd–Yb intermediate phases were evaluated (kJ/mol at.): −75 ± 4 (Pd{sub 21}Yb{sub 10}), −75 ± 3 (Pd{sub 5}Yb{sub 3}), −73 ± 3 (Pd{sub 4}Yb{sub 3}), and −66 ± 3 (PdYb). A modified version of the Pd–Yb phase diagram is also reported, re-drawn on the basis of literature data and of new experimental information recently become available.

Statistical thermodynamics of alloys

CERN Document Server

Gokcen, N A

1986-01-01

This book is intended for scientists, researchers, and graduate students interested in solutions in general, and solutions of metals in particular. Readers are assumed to have a good background in thermodynamics, presented in such books as those cited at the end of Chapter 1, "Thermo­ dynamic Background." The contents of the book are limited to the solutions of metals + metals, and metals + metalloids, but the results are also appli­ cable to numerous other types of solutions encountered by metallurgists, materials scientists, geologists, ceramists, and chemists. Attempts have been made to cover each topic in depth with numerical examples whenever necessary. Chapter 2 presents phase equilibria and phase diagrams as related to the thermodynamics of solutions. The emphasis is on the binary diagrams since the ternary diagrams can be understood in terms of the binary diagrams coupled with the phase rule, and the Gibbs energies of mixing. The cal­ culation of thermodynamic properties from the phase diagrams is ...

Modeling thermodynamics of Fe-N phases; characterisation of e-Fe2N1-z

DEFF Research Database (Denmark)

Pekelharing, M.I.; Böttger, A.; Somers, Marcel A.J.

1999-01-01

In order to arrive at modeling the thermodynamics of Fe-N phases, including long-range (LRO) and short-range ordering (SRO) of the N atoms, it is important to understand the role of N interstitially dissolved in an Fe-host lattice. The crystal structure of -Fe2N1-z consists of an h.c.p. iron...... sublattice and a hexagonal nitrogen sublattice formed by octahedral interstices of the Fe sublattice [1]. Two ground-state structures have been proposed for the ordered arrangement of the N atoms on their own sublattice [1], which were shown to be thermodynamically favourable [2]: configuration A for Fe2N1...... investigated with X-ray diffraction (XRD) and Mössbauer spectroscopy. A thermodynamic model accounting for the two configurations of LRO of the N atoms [2,3] was fitted to the N-absorption isotherm at 723 K and resulted in the occupancies of the sites of the nitrogen sublattice. A miscibility gap between...

Thermodynamic properties of uranium--mercury system

International Nuclear Information System (INIS)

Lee, T.S.

1979-01-01

The EMF values in the fused salt cells of the type U(α)/KCl--LiCl--BaCl 2 eutectic, UCl 3 /U--Hg alloy, for the different two-phase alloys in the uranium--mercury system have been measured and the thermodynamic properties of this system have been calculated. These calculated values are in good agreement with values based on mercury vapor pressure measurements made by previous investigators. The inconsistency of the thermodynamic properties with the phase diagram determined by Frost are also confirmed. A tentative phase diagram based on the thermodynamic properties measured in this work was constructed

Thermodynamics and statistical physics. 2. rev. ed.

International Nuclear Information System (INIS)

Schnakenberg, J.

2002-01-01

This textbook covers tthe following topics: Thermodynamic systems and equilibrium, irreversible thermodynamics, thermodynamic potentials, stability, thermodynamic processes, ideal systems, real gases and phase transformations, magnetic systems and Landau model, low temperature thermodynamics, canonical ensembles, statistical theory, quantum statistics, fermions and bosons, kinetic theory, Bose-Einstein condensation, photon gas

pycalphad: CALPHAD-based Computational Thermodynamics in Python

Directory of Open Access Journals (Sweden)

Richard Otis

2017-01-01

Full Text Available The pycalphad software package is a free and open-source Python library for designing thermodynamic models, calculating phase diagrams and investigating phase equilibria using the CALPHAD method. It provides routines for reading thermodynamic databases and solving the multi-component, multi-phase Gibbs energy minimization problem. The pycalphad software project advances the state of thermodynamic modeling by providing a flexible yet powerful interface for manipulating CALPHAD data and models. The key feature of the software is that the thermodynamic models of individual phases and their associated databases can be programmatically manipulated and overridden at run-time without modifying any internal solver or calculation code. Because the models are internally decoupled from the equilibrium solver and the models themselves are represented symbolically, pycalphad is an ideal tool for CALPHAD database development and model prototyping.

Palmitic acid/polypyrrole composites as form-stable phase change materials for thermal energy storage

International Nuclear Information System (INIS)

Silakhori, Mahyar; Metselaar, Hendrik Simon Cornelis; Mahlia, Teuku Meurah Indra; Fauzi, Hadi; Baradaran, Saeid; Naghavi, Mohammad Sajad

2014-01-01

Highlights: • A novel phase change composite of palmitic acid–polypyrrole(PA–PPy) was fabricated. • Thermal properties of PA–PPy are characterized in different mass ratios of PA–PPy. • Thermal cycling test showed that form stable PCM had a favorable thermal reliability. - Abstract: In this study a novel palmitic acid (PA)/polypyrrole (PPy) form-stable PCMs were readily prepared by in situ polymerization method. PA was used as thermal energy storage material and PPy was operated as supporting material. Form-stable PCMs were investigated by SEM (scanning electron microscopy) and FTIR (Fourier transform infrared spectrometer) analysis that illustrated PA Particles were wrapped by PPy particles. XRD (X-ray diffractometer) was used for crystalline phase of PA/PPy composites. Thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC) were used for investigating Thermal stability and thermal energy storage properties of prepared form-stable PCMs. According to the obtained results the form stable PCMs exhibited favorable thermal stability in terms of their phase change temperature. The form-stable PCMs (79.9 wt% loading of PA) were considered as the highest loading PCM with desirable latent heat storage of 166.3 J/g and good thermal stability. Accelerated thermal cycling tests also showed that form stable PCM had an acceptable thermal reliability. As a consequence of acceptable thermal properties, thermal stability and chemical stability, we can consider the new kind of form stable PCMs for low temperature solar thermal energy storage applications

A re-assessment of the thermodynamic properties of iodine condensed phases

International Nuclear Information System (INIS)

Arblaster, J.W.

2011-01-01

Highlights: → In the low temperature region below 298.15 K all previous reviews included highly discrepant experimental data points which should have been rejected. In the present review these data points have been rejected leading to a smooth specific heat curve similar to that obtained for solid bromine. The current values, especially at 298.15 K therefore differ considerably from other reviews but it is suggested are more acceptable. → For temperatures above 298.15 K previous reviews carried out unnecessary corrections to the experimental enthalpy measurements and therefore arrived at distorted values for the thermodynamic properties and since these corrections differed from one review to the next then the situation existed where different sets of thermodynamic tables existed and there was no way to suggest which was the correct one. In the present review the experimental values have been used without correction for calibration and therefore again represent a superior set of tables. → Since iodine is solid at room temperature then the question arises as to whether or not to divide the thermodynamic tables in to low temperature values based on 0 K and high temperature values based on 298.15 K. In this paper the values are based on 0 K only to be consistent with the analogues chlorine and bromine. However if in the opinion of the referees the divide ought to be used in this can be achieved quite easily. - Abstract: Thermodynamic properties of iodine have been calculated to 500 K. Specific heat anomalies accepted for the solid phase in previous reviews have been eliminated and a smooth specific heat curve derived. Corrections previously applied to high temperature solid and liquid enthalpy measurements were shown to be unnecessary.

A thermodynamic assessment of the La-Al system

International Nuclear Information System (INIS)

Yin, F.; Su, X.; Li, Z.; Huang, M.; Shi, Y.

2000-01-01

The optimized descriptions of the phase diagram and thermodynamic properties of the La-Al system have been obtained from experimental thermodynamic and phase diagram data by means of the computer program thermo-calc based on the least squares method, using models for the Gibbs energy of individual phases. The system contains six intermetallic compounds. A consistent set of thermodynamic parameters was derived. Optimized and experimental data are in good agreement (orig.)

Thermodynamic investigation of lime-enhanced molybdenite reduction using methane-containing gases

International Nuclear Information System (INIS)

Najafabadi, Samad Ghasemi; Abbasi, Mohammad Hasan; Saidi, Ali

2010-01-01

Lime-enhanced molybdenite reduction (LEMR) with methane-containing gases has been thermodynamically studied. The reaction proceeds through the direct oxidation of MoS 2 by CaO to form intermediate molybdenum oxidized species, MoO 2 and CaMoO 4 . The thermodynamics of Mo-O-C-H and Mo-Ca-O-C-H systems has been investigated instead of Mo-Ca-S-O-C-H system, as the sulfur is captured by calcium and forms a neutral compound (i.e. calcium sulfide). The role of reducing agent is the reduction of these oxidized species. Reduction of oxidized species by methane will yield Mo, Mo 2 C or MoC. The thermodynamic investigation resulted in construction of stability diagrams of molybdenum compounds. These diagrams were constructed for CH 4 -H 2 , CH 4 -H 2 -Ar and CH 4 -CO 2 -H 2 O gas mixtures. In addition to stability regions of Mo, Mo 2 C and MoC, the carbon deposition area was also identified. The results showed that by using appropriate gas composition and temperature, different molybdenum-containing phases would be stable thermodynamically while soot formation can be avoided.

Phase transition and thermodynamical geometry for Schwarzschild AdS black hole in AdS_5×S"5 spacetime

International Nuclear Information System (INIS)

Zhang, Jia-Lin; Cai, Rong-Gen; Yu, Hongwei

2015-01-01

We study the thermodynamics and thermodynamic geometry of a five-dimensional Schwarzschild AdS black hole in AdS_5×S"5 spacetime by treating the cosmological constant as the number of colors in the boundary gauge theory and its conjugate quantity as the associated chemical potential. It is found that the chemical potential is always negative in the stable branch of black hole thermodynamics and it has a chance to be positive, but appears in the unstable branch. We calculate the scalar curvatures of the thermodynamical Weinhold metric, Ruppeiner metric and Quevedo metric, respectively and we find that the scalar curvature in the Weinhold metric is always vanishing, while in the Ruppeiner metric the divergence of the scalar curvature is related to the divergence of the heat capacity with fixed chemical potential, and in the Quevedo metric the divergence of the scalar curvature is related to the divergence of the heat capacity with fixed number of colors and to the vanishing of the heat capacity with fixed chemical potential.

Graphene/phase change material nanocomposites: light-driven, reversible electrical resistivity regulation via form-stable phase transitions.

Science.gov (United States)

Wang, Yunming; Mi, Hongyi; Zheng, Qifeng; Ma, Zhenqiang; Gong, Shaoqin

2015-02-04

Innovative photoresponsive materials are needed to address the complexity of optical control systems. Here, we report a new type of photoresponsive nanomaterial composed of graphene and a form-stable phase change material (PCM) that exhibited a 3 orders of magnitude change in electrical resistivity upon light illumination while retaining its overall original solid form at the macroscopic level. This dramatic change in electrical resistivity also occurred reversibly through the on/off control of light illumination. This was attributed to the reversible phase transition (i.e., melting/recrystallization) behavior of the microscopic crystalline domains present in the form-stable PCM. The reversible phase transition observed in the graphene/PCM nanocomposite was induced by a reversible temperature change through the on/off control of light illumination because graphene can effectively absorb light energy and convert it to thermal energy. In addition, this graphene/PCM nanocomposite also possessed excellent mechanical properties. Such photoresponsive materials have many potential applications, including flexible electronics.

Theoretical physics 5 thermodynamics

CERN Document Server

Nolting, Wolfgang

2017-01-01

This concise textbook offers a clear and comprehensive introduction to thermodynamics, one of the core components of undergraduate physics courses. It follows on naturally from the previous volumes in this series, defining macroscopic variables, such as internal energy, entropy and pressure,together with thermodynamic principles. The first part of the book introduces the laws of thermodynamics and thermodynamic potentials. More complex themes are covered in the second part of the book, which describes phases and phase transitions in depth. Ideally suited to undergraduate students with some grounding in classical mechanics, the book is enhanced throughout with learning features such as boxed inserts and chapter summaries, with key mathematical derivations highlighted to aid understanding. The text is supported by numerous worked examples and end of chapter problem sets. About the Theoretical Physics series Translated from the renowned and highly successful German editions, the eight volumes of this series cove...

Thermodynamic modelling of alkali-activated slag cements

International Nuclear Information System (INIS)

Myers, Rupert J.; Lothenbach, Barbara; Bernal, Susan A.; Provis, John L.

2015-01-01

Highlights: • A thermodynamic modelling analysis of alkali-activated slag cements is presented. • Thermodynamic database describes zeolites, alkali carbonates, C–(N–)A–S–H gel. • Updated thermodynamic model for Mg–Al layered double hydroxides. • Description of phase assemblages in Na 2 SiO 3 - and Na 2 CO 3 -activated slag cements. • Phase diagrams for NaOH-activated and Na 2 SiO 3 -activated slag cements are simulated. - Abstract: This paper presents a thermodynamic modelling analysis of alkali-activated slag-based cements, which are high performance and potentially low-CO 2 binders relative to Portland cement. The thermodynamic database used here contains a calcium (alkali) aluminosilicate hydrate ideal solid solution model (CNASH-ss), alkali carbonate and zeolite phases, and an ideal solid solution model for a hydrotalcite-like Mg–Al layered double hydroxide phase. Simulated phase diagrams for NaOH- and Na 2 SiO 3 -activated slag-based cements demonstrate the high stability of zeolites and other solid phases in these materials. Thermodynamic modelling provides a good description of the chemical compositions and types of phases formed in Na 2 SiO 3 -activated slag cements over the most relevant bulk chemical composition range for these cements, and the simulated volumetric properties of the cement paste are consistent with previously measured and estimated values. Experimentally determined and simulated solid phase assemblages for Na 2 CO 3 -activated slag cements were also found to be in good agreement. These results can be used to design the chemistry of alkali-activated slag-based cements, to further promote the uptake of this technology and valorisation of metallurgical slags

Thermodynamic Functions of Yttrium Trifluoride and Its Dimer in the Gas Phase

Science.gov (United States)

Osina, E. L.; Kovtun, D. M.

2018-05-01

New calculations of the functions for YF3 and Y2F6 in the gas phase using quantum-chemical calculations by MP2 and CCSD(T) methods are performed in connection with the ongoing work on obtaining reliable thermodynamic data of yttrium halides. The obtained values are entered in the database of the IVTANTERMO software complex. Equations approximating the temperature dependence of the reduced Gibbs energy in the T = 298.15-6000 K range of temperatures are presented.

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.

Order-disorder phase transitions in Au-Cu nanocubes: from nano-thermodynamics to synthesis.

Science.gov (United States)

Mendoza-Cruz, R; Bazán-Diaz, L; Velázquez-Salazar, J J; Samaniego-Benitez, J E; Ascencio-Aguirre, F M; Herrera-Becerra, R; José-Yacamán, M; Guisbiers, G

2017-07-13

Catalysts have been widely used in industries and can be optimized by tuning the composition and chemical ordering of the elements involved in the nano-alloy. Among bi-metallic alloys, the Au-Cu system is of particular interest because it exhibits ordered phases at low temperatures. Nevertheless, the temperature at which these ordered structures are formed is totally unknown at the nanoscale. Consequently, to speed up the development of these catalysts, this paper theoretically predicts the structural phase transitions between ordered and disordered phases for the Au-Cu system by using nano-thermodynamics. Following the predictions, the suggested annealing temperatures have been carefully chosen and consequently, Au-Cu ordered nanocubes have been successfully synthesized through a solventless protocol. The results are fully supported by electron microscopy observations.

Thermodynamics of nuclear materials

International Nuclear Information System (INIS)

Rand, M.H.

1975-01-01

A report is presented of the Fourth International Symposium on Thermodynamics of Nuclear Materials held in Vienna, 21-25 October 1974. The technological theme of the Symposium was the application of thermodynamics to the understanding of the chemistry of irradiated nuclear fuels and to safety assessments for hypothetical accident conditions in reactors. The first four sessions were devoted to these topics and they were followed by four more sessions on the more basic thermodynamics, phase diagrams and the thermodynamic properties of a wide range of nuclear materials. Sixty-seven papers were presented

Thermodynamics for Chemists, Physicists and Engineers

CERN Document Server

Hołyst, Robert

2012-01-01

Thermodynamics is an essential part of chemical physics and is of fundamental importance in physics, chemistry and engineering courses. This textbook takes an interdisciplinary approach to the subject and is therefore suitable for undergraduates in all those courses. The book is an introduction to phenomenological thermodynamics and its applications to phase transitions and chemical reactions, with some references to statistical mechanics. It strikes the balance between the rigorousness of the Callen text and phenomenological approach of the Atkins text. The book is divided in three parts. The first introduces the postulates and laws of thermodynamics and complements these initial explanations with practical examples. The second part is devoted to applications of thermodynamics to phase transitions in pure substances and mixtures. The third part covers thermodynamic systems in which chemical reactions take place. There are some sections on more advanced topics such as thermodynamic potentials, natural variabl...

Thermodynamic study of selected monoterpenes III

International Nuclear Information System (INIS)

Štejfa, Vojtěch; Fulem, Michal; Růžička, Květoslav; Červinka, Ctirad

2014-01-01

Highlights: • (−)-trans-Pinane, (+)-Δ-carene, eucalyptol, and limonene were studied. • New thermodynamic data were measured and calculated. • Many of thermodynamic data are reported for the first time. - Abstract: A thermodynamic study of selected monoterpenes, (−)-trans-pinane, (+)-Δ-carene, eucalyptol, (+)-limonene, and (−)-limonene, is presented in this work. The vapor pressure measurements were performed using the static method over the environmentally important temperature range (238 to 308) K. Liquid heat capacities were measured by Tian–Calvet calorimetry in the temperature interval (258 to 355) K. The phase behavior was investigated by differential scanning calorimetry (DSC) from T = 183 K. The thermodynamic properties in the ideal-gas state were calculated by combining statistical thermodynamic and density functional theory (DFT) calculations. Calculated ideal-gas heat capacities and experimental data for vapor pressures and condensed phase heat capacities were treated simultaneously to obtain a consistent thermodynamic description

Interphase thermodynamic bond in heterogeneous alloys: effects on alloy properties

International Nuclear Information System (INIS)

Savchenko, A.M.; Konovalov, Yu.V.; Yuferov, O.I.

2005-01-01

Inconsistency between a conventional thermodynamic description of alloys as a mechanical mixture of phases and a real alloys state as a common thermodynamic system in which there is a complicated physical-chemical phases interaction has been considered. It is supposed that in heterogeneous alloys (eutectic ones, for instance), so called interphase thermodynamic bond can become apparent due to a partial electron levels splitting under phase interaction. Thermodynamic description of phase equilibrium in alloys is proposed taking into account a thermodynamic bond for the system with phase diagram of eutectic type, and methods of the value of this bond estimation are presented. Experimental evidence (Al-Cu-Si, Al-Si-Mg-Cu, U-Mo + Al) of the effect of interphase thermodynamic bond on temperature and enthalpy of melting of alloys are produced as well as possibility of its effects on alloys electrical conduction, strength, heat and corrosion resistance is substantiated theoretically [ru

Thermodynamics of (2 +1 )-dimensional black holes in Einstein-Maxwell-dilaton gravity

Science.gov (United States)

Dehghani, M.

2017-08-01

In this paper, the linearly charged three-dimensional Einstein's theory coupled to a dilatonic field has been considered. It has been shown that the dilatonic potential must be considered in a form of generalized Liouville-type potential. Two new classes of charged dilatonic black hole solutions, as the exact solutions to the Einstein-Maxwell-dilaton (EMd) gravity, have been obtained and their properties have been studied. The conserved charge and mass related to both of the new EMd black holes have been calculated. Through comparison of the thermodynamical extensive quantities (i.e., temperature and entropy) obtained from both, the geometrical and the thermodynamical methods, the validity of first law of black hole thermodynamics has been investigated for both of the new black holes we just obtained. At the final stage, making use of the canonical ensemble method and regarding the black hole heat capacity, the thermal stability or phase transition of the new black hole solutions have been analyzed. It has been shown that there is a specific range for the horizon radius in such a way that the black holes with the horizon radius in that range are locally stable. Otherwise, they are unstable and may undergo type one or type two phase transitions to be stabilized.

Thermodynamic modelling of phase equilibrium in system Ti-B-Si-C, synthesis and phases composition of borides and carbides layers on titanic alloyVT-1 at electron beam treatment in vacuum

Science.gov (United States)

Smirnyagina, N. N.; Khaltanova, V. M.; Lapina, A. E.; Dasheev, D. E.

2017-01-01

Composite layers on the basis of carbides and borides the titan and silicon on titanic alloy VT-1 are generated at diffused saturation in vacuum. Formation in a composite of MAX phase Ti3SiC2 is shown. Thermodynamic research of phase equilibrium in systems Ti-Si-C and Ti-B-C in the conditions of high vacuum is executed. The thermodynamics, formation mechanisms of superfirm layers borides and carbides of the titan and silicon are investigated.

Discussing the precipitation behavior of {sigma} phase using diffusion equation and thermodynamic simulation in dissimilar stainless steels

Energy Technology Data Exchange (ETDEWEB)

Hsieh, Chih-Chun [Department of Materials Science and Engineering, National Chung Hsing University, 250 Kuo-Kuang Rd., Taichung 402, Taiwan (China); Wu, Weite, E-mail: wwu@dragon.nchu.edu.t [Department of Materials Science and Engineering, National Chung Hsing University, 250 Kuo-Kuang Rd., Taichung 402, Taiwan (China)

2010-09-17

Research highlights: This article concentrates the phase transformation in {delta} {yields} {sigma} in dissimilar stainless steels using the Vitek equation and thermodynamics simulation during the multi-pass welding. The phase transformation in {delta} {yields} {sigma} is very important to the properties of stainless steel composites. In this study, the diffusion behavior of Cr, Ni and Si in the {delta}, {sigma}, and {gamma} phases were discussed using the DSC analysis and diffusion equation calculation. This method has a novelty for discussing the phase transformation in {delta} {yields} {sigma} in the dissimilar stainless steel. We hope that we can give a scientific contribution for the phase transformation of the dissimilar stainless steels during the multi-pass welding. - Abstract: This study performed a precipitation examination of the {sigma} phase using the Vitek diffusion equation and thermodynamic simulation in dissimilar stainless steels during multi-pass welding. The results of the experiment demonstrate that the diffusion rates (D{sub Cr}{sup {delta}} and D{sub Ni}{sup {delta}}) of Cr and Ni are higher in {delta}-ferrite than (D{sub Cr}{sup {gamma}} and D{sub Ni}{sup {gamma}}) in the {gamma} phase and that they facilitate the precipitation of {sigma} phase in the third pass fusion zone. When the diffusion activation energy of Cr in {delta}-ferrite is equal to that of Ni in {delta}-ferrite (Q{sub dCr}{sup {delta}}=Q{sub dNi}{sup {delta}}), phase transformation of the {delta} {yields} {sigma} can be occurred.

Construction of the Al-Ni-Si phase diagram over the whole composition and temperature ranges: thermodynamic modeling supported by key experiments and first-principles calculations

Energy Technology Data Exchange (ETDEWEB)

Xiong Wei; Du Yong; Wang Jiong; Zhang Wei-Wei [State Key Lab. of Powder Metallurgy, Central South Univ., Changsha (China); Hu Rong-Xiang; Nash, P. [Thermal Processing Technology Center, Illinois Inst. of Tech., Chicago (United States); Lu Xiao-Gang [Thermo-Calc AB, Stockholm Technology Park, Stockholm (Sweden)

2008-06-15

An extensive thermodynamic investigation of the Al-Ni-Si system is carried out via an integrated approach of calculation of phase diagrams, first-principles calculations, and key experiments. Eighteen decisive alloys are prepared in order to verify the existence of the previously reported ternary compounds and to provide new phase equilibrium data. Phase compositions, microstructure, and phase transition temperatures are determined using the combined techniques of X-ray diffraction, scanning electron microscopy, energy dispersion X-ray analysis, and differential thermal analysis. The order/disorder transition between disordered bccA2 and ordered bccB2 phases as well as that between disordered fccA1 and ordered L1{sub 2} phase are described using a two-sublattice model. A self-consistent parameter set is finally obtained by considering the huge amount of experimental data including 13 vertical sections and 5 isothermal sections from both the literature and the present experiments. Almost all of the reliable phase diagram data can be well described by the present modeling. The reliability of the calculated thermodynamic properties for ternary phases is verified through enthalpy measurement employing drop calorimetry and first-principles calculations. The thermodynamic parameters obtained can also successfully predict most of the thermodynamic properties and describe the solidification path for the selected as-cast alloy Al{sub 6}Ni{sub 55}Si{sub 39}. (orig.)

Analytical description of thermodynamic properties of steam, water and the phase interface for use in CFD

Science.gov (United States)

Hrubý, Jan; Duška, Michal

2014-03-01

We present a system of analytical equations for computation of all thermodynamic properties of dry steam and liquid water (undesaturated, saturated and metastable supersaturated) and properties of the liquid-vapor phase interface. The form of the equations is such that it enables computation of all thermodynamic properties for independent variables directly related to the balanced quantities - total mass, liquid mass, energy, momenta. This makes it suitable for the solvers of fluid dynamics equations in the conservative form. Thermodynamic properties of dry steam and liquid water are formulated in terms of special thermodynamic potentials and all properties are obtained as analytical derivatives. For the surface tension, the IAPWS formula is used. The interfacial internal energy is derived from the surface tension and it is used in the energy balance. Unlike common models, the present one provides real (contrary to perfect gas approximation) properties of steam and water and reflects the energetic effects due to the surface tension. The equations are based on re-fitting the reference formulation IAPWS-95 and selected experimental data. The mathematical structure of the equations is optimized for fast computation.

Linearization-based method for solving a multicomponent diffusion phase-field model with arbitrary solution thermodynamics

Science.gov (United States)

Welland, M. J.; Tenuta, E.; Prudil, A. A.

2017-06-01

This article describes a phase-field model for an isothermal multicomponent, multiphase system which avoids implicit interfacial energy contributions by starting from a grand potential formulation. A method is developed for incorporating arbitrary forms of the equilibrium thermodynamic potentials in all phases to determine an explicit relationship between chemical potentials and species concentrations. The model incorporates variable densities between adjacent phases, defect migration, and dependence of internal pressure on object dimensions ranging from the macro- to nanoscale. A demonstrative simulation of an overpressurized nanoscopic intragranular bubble in nuclear fuel migrating to a grain boundary under kinetically limited vacancy diffusion is shown.

Exploring N-Rich Phases in Li(x)N(y) Clusters for Hydrogen Storage at Nanoscale.

Science.gov (United States)

Bhattacharya, Amrita; Bhattacharya, Saswata

2015-09-17

We have performed cascade genetic algorithm and ab initio atomistic thermodynamics under the framework of first-principles-based hybrid density functional theory to study the (meta-)stability of a wide range of Li(x)N(y) clusters. We found that hybrid xc-functional is essential to address this problem as a local/semilocal functional simply fails even to predict a qualitative prediction. Most importantly, we find that though in bulk lithium nitride, the Li-rich phase, that is, Li3N, is the stable stoichiometry; in small Li(x)N(y) clusters, N-rich phases are more stable at thermodynamic equilibrium. We further show that these N-rich clusters are promising hydrogen storage material because of their easy adsorption and desorption ability at respectively low (≤300 K) and moderately high temperature (≥600 K).

Insight into the microscopic structure of an AdS black hole from a thermodynamical phase transition.

Science.gov (United States)

Wei, Shao-Wen; Liu, Yu-Xiao

2015-09-11

Comparing with an ordinary thermodynamic system, we investigate the possible microscopic structure of a charged anti-de Sitter black hole completely from the thermodynamic viewpoint. The number density of the black hole molecules is introduced to measure the microscopic degrees of freedom of the black hole. We found that the number density suffers a sudden change accompanied by a latent heat when the black hole system crosses the small-large black hole coexistence curve, while when the system passes the critical point, it encounters a second-order phase transition with a vanishing latent heat due to the continuous change of the number density. Moreover, the thermodynamic scalar curvature suggests that there is a weak attractive interaction between two black hole molecules. These phenomena might cast new insight into the underlying microscopic structure of a charged anti-de Sitter black hole.

Thermodynamical stability of FRW models with quintessence

Science.gov (United States)

Sharif, M.; Ashraf, Sara

2018-03-01

In this paper, we study the thermodynamic stability of quintessence in the background of homogeneous and isotropic universe model. For the evolutionary picture, we consider two different forms of potentials and investigate the behavior of different physical parameters. We conclude that the quintessence model expands adiabatically and this expansion is thermodynamically stable for both potentials with suitable model parameters.

Thermodynamic modeling of the formation and stability of small tin clusters and their ions

International Nuclear Information System (INIS)

Kodlaa, A.; Suliman, A.

2005-01-01

Based on the results of previous quantum-chemical study of electronic structure properties for neutral and single positively and negatively charged thin clusters in the size range of N 2-17 atoms, and on the thermodynamic laws, we have studied the thermodynamic properties of tin clusters and their ions. The characteristic amounts (cohesive enthalpy, formation enthalpy, fragmentation enthalpy, entropy and free enthalpy) for the formation and stability of these clusters at different temperatures were calculated. From the results, which are presented and discussed in this work, one can observe the following: The tin clusters Sn N (N=2-17) and their cations Sn + N and anions Sn - N are formed in the gas phase, and this agrees with experimental results. The clusters Sn 3 and Sn 1 0 are the most stable clusters of all. Here we also, find a correspondence with the results of the experimental studies. Our results go beyond that since we have found Sn 1 5 is also specially stable. By this thermodynamic study we could evaluate approximately the formation and stability of small neutral, single positively and negatively charged tin clusters. It has also allowed us to study the effects of the temperature on the formation and stability of these clusters. The importance of such study is not only what mentioned above, but it is also the first thermodynamic study for modeling the formation and stability of small tin clusters. (author)

Equilibrium econophysics: A unified formalism for neoclassical economics and equilibrium thermodynamics

Science.gov (United States)

Sousa, Tânia; Domingos, Tiago

2006-11-01

We develop a unified conceptual and mathematical structure for equilibrium econophysics, i.e., the use of concepts and tools of equilibrium thermodynamics in neoclassical microeconomics and vice versa. Within this conceptual structure the results obtained in microeconomic theory are: (1) the definition of irreversibility in economic behavior; (2) the clarification that the Engel curve and the offer curve are not descriptions of real processes dictated by the maximization of utility at constant endowment; (3) the derivation of a relation between elasticities proving that economic elasticities are not all independent; (4) the proof that Giffen goods do not exist in a stable equilibrium; (5) the derivation that ‘economic integrability’ is equivalent to the generalized Le Chatelier principle and (6) the definition of a first order phase transition, i.e., a transition between separate points in the utility function. In thermodynamics the results obtained are: (1) a relation between the non-dimensional isothermal and adiabatic compressibilities and the increase or decrease in the thermodynamic potentials; (2) the distinction between mathematical integrability and optimization behavior and (3) the generalization of the Clapeyron equation.

Thermodynamics of the Heat-Flux Avalanches at the First-Order Magnetic Transition in Magnetocaloric Materials

Science.gov (United States)

Piazzi, Marco; Bennati, Cecilia; Basso, Vittorio

2017-10-01

We investigate the kinetics of first-order magnetic phase transitions by measuring and modeling the heat-flux avalanches corresponding to the irreversible motion of the phase-boundary interface separating the coexisting low- and high-temperature stable magnetic phases. By means of out-of-equilibrium thermodynamics, we encompass the damping mechanisms of the boundary motion in a phenomenological parameter αs. By analyzing the time behavior of the heat-flux signals measured on La (Fe -Mn -Si )13-H magnetocaloric compounds through Peltier calorimetry temperature scans performed at low rates, we relate the linear rise of the individual avalanches to the intrinsic-damping parameter αs.

Thermodynamic modeling of the Sr-Co-Fe-O system

DEFF Research Database (Denmark)

Zhang, Wei Wei; Povoden-Karadeniz, Erwin; Chen, Ming

2016-01-01

This paper reviews and assesses phase equilibria and thermodynamic properties of phases in the Sr-Co-Fe-O system, with a focus on oxides, especially the SrCo1 - xFexO3 - δ perovskite. In our work, the SrCo1 - xFexO3 - δ perovskite was modeled with a three-sublattice model, where the three...... sublattices correspond to the A, B and oxygen sites in an ABO3 perovskite, respectively. A number of other important ternary oxide phases in Sr-Co-O and Sr-Co-Fe-O were also considered. Available thermodynamic and phase diagram data were carefully assessed. A thermodynamic description of Sr-Co-O was derived...... using the CALPHAD approach and was further extrapolated to that of Sr-Co-Fe-O. The thermodynamic database of Sr-Co-Fe-O established in this work allows for calculating phase diagrams, thermodynamic properties, cation distribution and defect chemistry properties, and therefore enables material...

Thermodynamic nonequilibrium phase change behavior and thermal properties of biological solutions for cryobiology applications.

Science.gov (United States)

Han, Bumsoo; Bischof, John C

2004-04-01

Understanding the phase change behavior of biomaterials during freezing/thawing including their thermal properties at low temperatures is essential to design and improve cryobiology applications such as cryopreservation and cryosurgery. However, knowledge of phase change behavior and thermal properties of various biomaterials is still incomplete, especially at cryogenic temperatures (solutions--either water-NaCl or phosphate buffered saline (PBS)--with various chemical additives were investigated. The chemical additives studied are glycerol and raffinose as CPAs, an AFP (Type III, molecular weight = 6500), and NaCl as a cryosurgical adjuvant. The phase change behavior was investigated using a differential scanning calorimeter (DSC) and a cryomicroscope. The specific and latent heat of these solutions were also measured with the DSC. The saline solutions have two distinct phase changes--water/ice and eutectic phase changes. During freezing, eutectic solidification of both water-NaCl and PBS are significantly supercooled below their thermodynamic equilibrium eutectic temperatures. However, their melting temperatures are close to thermodynamic equilibrium during thawing. These eutectic phase changes disappear when even a small amount (0.1 M glycerol) of CPA was added, but they are still observed after the addition of an AFP. The specific heats of these solutions are close to that of ice at very low temperatures (< or = -100 degrees C) regardless of the additives, but they increase between -100 degrees C and -30 degrees C with the addition of CPAs. The amount of latent heat, which is evaluated with sample weight, generally decreases with the addition of the additives, but can be normalized to approximately 300 J/g based on the weight of water which participates in the phase change. This illustrates that thermal properties, especially latent heat, of a biomaterial should be evaluated based on the understanding of its phase change behavior. The results of the present

Thermodynamic assessment of the zirconia-urania system

International Nuclear Information System (INIS)

Yashima, Masatomo; Koura, Toshiaki; Du, Y.; Yoshimura, Masahiro

1996-01-01

An optimal thermodynamic data set for the zirconia-urania system is devaluated by the CALPHAD (CALculation of PHAse Diagrams) method. A regular solution model is applied to all phases of the cubic, tetragonal, and monoclinic solid solutions and the liquid. Comparisons between calculated and measured phase diagrams show that most of the experimental information is satisfactorily accounted for by thermodynamic calculations

The TbBr3–LiBr binary system: Experimental thermodynamic investigation and assessment of phase diagram

International Nuclear Information System (INIS)

Rycerz, L.; Gong, W.; Gaune-Escard, M.

2013-01-01

Highlights: ► DSC measurements for the (LiBr + TbBr 3 ) system. ► congruently Li3TbBr 6 and incongruently melting Li5TbBr 8 compounds. ► Thermodynamic description of the liquid phase in the (LiBr + TbBr 3 ) system. ► Assessment with a two-sublattice ionic solution model. - Abstract: DSC was used to study the phase equilibrium in the TbBr 3 –LiBr binary system. The results obtained provided a basis for constructing the phase diagram of this system. It exhibits two compounds: Li 5 TbBr 8 , which decomposes in the solid state at 611 K, and Li 3 TbBr 6 , which melts congruently at 785 K with the related enthalpy 59.1 kJ·mol −1 . The binary LiBr–TbBr 3 system was then optimized using the available experimental information on phase diagram and thermodynamic properties. A two-sub-lattice ionic solution model (Li + ) P :(Br − , TbBr 6 −3 , TbBr 3 ) Q was adopted to describe the liquid phase. The present assessment of the binary LiBr–TbBr 3 system was in good agreement with the corresponding experimental data and confirmed their consistency.

Unified geometric description of black hole thermodynamics

International Nuclear Information System (INIS)

Alvarez, Jose L.; Quevedo, Hernando; Sanchez, Alberto

2008-01-01

In the space of thermodynamic equilibrium states we introduce a Legendre invariant metric which contains all the information about the thermodynamics of black holes. The curvature of this thermodynamic metric becomes singular at those points where, according to the analysis of the heat capacities, phase transitions occur. This result is valid for the Kerr-Newman black hole and all its special cases and, therefore, provides a unified description of black hole phase transitions in terms of curvature singularities.

Thermodynamic Calculations for Systems Biocatalysis

DEFF Research Database (Denmark)

Abu, Rohana; Gundersen, Maria T.; Woodley, John M.

2015-01-01

the transamination of a pro-chiral ketone into a chiral amine (interesting in many pharmaceutical applications). Here, the products are often less energetically stable than the reactants, meaning that the reaction may be thermodynamically unfavourable. As in nature, such thermodynamically-challenged reactions can...... on the basis of kinetics. However, many of the most interesting non-natural chemical reactions which could potentially be catalysed by enzymes, are thermodynamically unfavourable and are thus limited by the equilibrium position of the reaction. A good example is the enzyme ω-transaminase, which catalyses...... be altered by coupling with other reactions. For instance, in the case of ω-transaminase, such a coupling could be with alanine dehydrogenase. Herein, the aim of this work is to identify thermodynamic bottlenecks within a multi-enzyme process, using group contribution method to calculate the Gibbs free...

Pitfalls and feedback when constructing topological pressure-temperature phase diagrams

Science.gov (United States)

Ceolin, R.; Toscani, S.; Rietveld, Ivo B.; Barrio, M.; Tamarit, J. Ll.

2017-04-01

The stability hierarchy between different phases of a chemical compound can be accurately reproduced in a topological phase diagram. This type of phase diagrams may appear to be the result of simple extrapolations, however, experimental complications quickly increase in the case of crystalline trimorphism (and higher order polymorphism). To ensure the accurate positioning of stable phase domains, a topological phase diagram needs to be consistent. This paper gives an example of how thermodynamic feedback can be used in the topological construction of phase diagrams to ensure overall consistency in a phase diagram based on the case of piracetam crystalline trimorphism.

Molecular thermodynamics using fluctuation solution theory

DEFF Research Database (Denmark)

Ellegaard, Martin Dela

. The framework relates thermodynamic variables to molecular pair correlation functions of liquid mixtures. In this thesis, application of the framework is illustrated using two approaches: 1. Solubilities of solid solutes in mixed solvent systems are determined from fluctuation solution theory application......Properties of chemicals and their mutual phase equilibria are critical variables in process design. Reliable estimates of relevant equilibrium properties, from thermodynamic models, can form the basis of good decision making in the development phase of a process design, especially when access...... to relevant experimental data is limited. This thesis addresses the issue of generating and using simple thermodynamic models within a rigorous statistical mechanical framework, the so-called fluctuation solution theory, from which relations connecting properties and phase equilibria can be obtained...

Applied chemical engineering thermodynamics

CERN Document Server

Tassios, Dimitrios P

1993-01-01

Applied Chemical Engineering Thermodynamics provides the undergraduate and graduate student of chemical engineering with the basic knowledge, the methodology and the references he needs to apply it in industrial practice. Thus, in addition to the classical topics of the laws of thermodynamics,pure component and mixture thermodynamic properties as well as phase and chemical equilibria the reader will find: - history of thermodynamics - energy conservation - internmolecular forces and molecular thermodynamics - cubic equations of state - statistical mechanics. A great number of calculated problems with solutions and an appendix with numerous tables of numbers of practical importance are extremely helpful for applied calculations. The computer programs on the included disk help the student to become familiar with the typical methods used in industry for volumetric and vapor-liquid equilibria calculations.

First-principles calculations of the thermodynamic properties of transuranium elements in a molten salt medium

International Nuclear Information System (INIS)

Noh, Seunghyo; Kwak, Dohyun; Lee, Juseung; Kang, Joonhee; Han, Byungchan

2014-01-01

We utilized first-principles density-functional-theory (DFT) calculations to evaluate the thermodynamic feasibility of a pyroprocessing methodology for reducing the volume of high-level radioactive materials and recycling spent nuclear fuels. The thermodynamic properties of transuranium elements (Pu, Np and Cm) were obtained in electrochemical equilibrium with a LiCl-KCl molten salt as ionic phases and as adsorbates on a W(110) surface. To accomplish the goal, we rigorously calculated the double layer interface structures on an atomic resolution, on the thermodynamically most stable configurations on W(110) surfaces and the chemical activities of the transuranium elements for various coverages of those elements. Our results indicated that the electrodeposition process was very sensitive to the atomic level structures of Cl ions at the double-layer interface. Our studies are easily expandable to general electrochemical applications involving strong redox reactions of transition metals in non-aqueous solutions.

Thermodynamic modeling of the Co-Fe-O system

DEFF Research Database (Denmark)

Zhang, Weiwei; Chen, Ming

2013-01-01

As a part of the research project aimed at developing a thermodynamic database of the La-Sr-Co-Fe-O system for applications in Solid Oxide Fuel Cells (SOFCs), the Co-Fe-O subsystem was thermodynamically re-modeled in the present work using the CALPHAD methodology. The solid phases were described...... using the Compound Energy Formalism (CEF) and the ionized liquid was modeled with the ionic two-sublattice model based on CEF. A set of self-consistent thermodynamic parameters was obtained eventually. Calculated phase diagrams and thermodynamic properties are presented and compared with experimental...

Thermodynamic investigation of lime-enhanced molybdenite reduction using methane-containing gases

Energy Technology Data Exchange (ETDEWEB)

Najafabadi, Samad Ghasemi, E-mail: samad_ghasemi@yahoo.com [Materials Engineering Department, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Abbasi, Mohammad Hasan; Saidi, Ali [Materials Engineering Department, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

2010-05-20

Lime-enhanced molybdenite reduction (LEMR) with methane-containing gases has been thermodynamically studied. The reaction proceeds through the direct oxidation of MoS{sub 2} by CaO to form intermediate molybdenum oxidized species, MoO{sub 2} and CaMoO{sub 4}. The thermodynamics of Mo-O-C-H and Mo-Ca-O-C-H systems has been investigated instead of Mo-Ca-S-O-C-H system, as the sulfur is captured by calcium and forms a neutral compound (i.e. calcium sulfide). The role of reducing agent is the reduction of these oxidized species. Reduction of oxidized species by methane will yield Mo, Mo{sub 2}C or MoC. The thermodynamic investigation resulted in construction of stability diagrams of molybdenum compounds. These diagrams were constructed for CH{sub 4}-H{sub 2}, CH{sub 4}-H{sub 2}-Ar and CH{sub 4}-CO{sub 2}-H{sub 2}O gas mixtures. In addition to stability regions of Mo, Mo{sub 2}C and MoC, the carbon deposition area was also identified. The results showed that by using appropriate gas composition and temperature, different molybdenum-containing phases would be stable thermodynamically while soot formation can be avoided.

Thermodynamic and kinetic theory of nucleation, deliquescence and efflorescence transitions in the ensemble of droplets on soluble particles.

Science.gov (United States)

Shchekin, Alexander K; Shabaev, Ilya V; Hellmuth, Olaf

2013-02-07

Thermodynamic and kinetic peculiarities of nucleation, deliquescence and efflorescence transitions in the ensemble of droplets formed on soluble condensation nuclei from a solvent vapor have been considered. The interplay of the effects of solubility and the size of condensation nuclei has been analyzed. Activation barriers for the deliquescence and phase transitions and for the reverse efflorescence transition have been determined as functions of the relative humidity of the vapor-gas atmosphere, initial size, and solubility of condensation nuclei. It has been demonstrated that, upon variations in the relative humidity of the atmosphere, the crossover in thermodynamically stable and unstable variables of the droplet state takes place. The physical meaning of stable and unstable variables has been clarified. The kinetic equations for establishing equilibrium and steady distributions of binary droplets have been solved. The specific times for relaxation, deliquescence and efflorescence transitions have been calculated.

Thermodynamical stability of the Bardeen black hole

Energy Technology Data Exchange (ETDEWEB)

Bretón, Nora [Dpto. de Física, Centro de Investigación y de Estudios Avanzados del I. P. N., Apdo. 14-740, D.F. (Mexico); Perez Bergliaffa, Santiago E. [Dpto. de Física, U. Estado do Rio de Janeiro (Brazil)

2014-01-14

We analyze the stability of the regular magnetic Bardeen black hole both thermodynamically and dynamically. For the thermodynamical analysis we consider a microcanonical ensemble and apply the turning point method. This method allows to decide a change in stability (or instability) of a system, requiring only the assumption of smoothness of the area functional. The dynamical stability is asserted using criteria based on the signs of the Lagrangian and its derivatives. It turns out from our analysis that the Bardeen black hole is both thermodynamically and dynamically stable.

Analytical description of thermodynamic properties of steam, water and the phase interface for use in CFD

Directory of Open Access Journals (Sweden)

Hrubý Jan

2014-03-01

Full Text Available We present a system of analytical equations for computation of all thermodynamic properties of dry steam and liquid water (undesaturated, saturated and metastable supersaturated and properties of the liquid-vapor phase interface. The form of the equations is such that it enables computation of all thermodynamic properties for independent variables directly related to the balanced quantities - total mass, liquid mass, energy, momenta. This makes it suitable for the solvers of fluid dynamics equations in the conservative form. Thermodynamic properties of dry steam and liquid water are formulated in terms of special thermodynamic potentials and all properties are obtained as analytical derivatives. For the surface tension, the IAPWS formula is used. The interfacial internal energy is derived from the surface tension and it is used in the energy balance. Unlike common models, the present one provides real (contrary to perfect gas approximation properties of steam and water and reflects the energetic effects due to the surface tension. The equations are based on re-fitting the reference formulation IAPWS-95 and selected experimental data. The mathematical structure of the equations is optimized for fast computation.

Thermodynamics of nuclear materials

International Nuclear Information System (INIS)

1962-01-01

The first session of the symposium discussed in general the thermodynamic properties of actinides, including thorium, uranium and Plutonium which provide reactor fuel. The second session was devoted to applications of thermodynamic theory to the study of nuclear materials, while the experimental techniques for the determination of thermodynamic data were examined at the next session. The thermodynamic properties of alloys were considered at a separate session, and another session was concerned with solids other than alloys. Vaporization processes, which are of special interest in the development of high-temperature reactors, were discussed at a separate session. The discussions on the methods of developing the data and ascertaining their accuracy were especially useful in highlighting the importance of determining whether any given data are reliable before they can be put to practical application. Many alloys and refractory materials (i. e. materials which evaporate only at very high temperatures) are of great importance in nuclear technology, and some of these substances are extremely complex in their chemical composition. For example, until recently the phase composition of the oxides of thorium, uranium and plutonium had been only very imperfectly understood, and the same was true of the carbides of these elements. Recent developments in experimental techniques have made it possible to investigate the phase composition of these complex materials as well as the chemical species of these materials in the gaseous phase. Recent developments in measuring techniques, such as fluorine bomb calorimetry and Knudsen effusion technique, have greatly increased the accuracy of thermodynamic data

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)

On thermodynamic and microscopic reversibility

International Nuclear Information System (INIS)

Crooks, Gavin E

2011-01-01

The word 'reversible' has two (apparently) distinct applications in statistical thermodynamics. A thermodynamically reversible process indicates an experimental protocol for which the entropy change is zero, whereas the principle of microscopic reversibility asserts that the probability of any trajectory of a system through phase space equals that of the time reversed trajectory. However, these two terms are actually synonymous: a thermodynamically reversible process is microscopically reversible, and vice versa

Thermodynamic Modelling of Phase Transformation in a Multi-Component System

Science.gov (United States)

Vala, J.

2007-09-01

Diffusion in multi-component alloys can be characterized by the vacancy mechanism for substitutional components, by the existence of sources and sinks for vacancies and by the motion of atoms of interstitial components. The description of diffusive and massive phase transformation of a multi-component system is based on the thermodynamic extremal principle by Onsager; the finite thickness of the interface between both phases is respected. The resulting system of partial differential equations of evolution with integral terms for unknown mole fractions (and additional variables in case of non-ideal sources and sinks for vacancies), can be analyzed using the method of lines and the finite difference technique (or, alternatively, the finite element one) together with the semi-analytic and numerical integration formulae and with certain iteration procedure, making use of the spectral properties of linear operators. The original software code for the numerical evaluation of solutions of such systems, written in MATLAB, offers a chance to simulate various real processes of diffusional phase transformation. Some results for the (nearly) steady-state real processes in substitutional alloys have been published yet. The aim of this paper is to demonstrate that the same approach can handle both substitutional and interstitial components even in case of a general system of evolution.

Thermodynamic modeling of the Al-U and Co-U systems

International Nuclear Information System (INIS)

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

2008-01-01

The thermodynamic assessments of the Al-U and Co-U systems have been carried out by using the CALPHAD (Calculation of Phase Diagrams) method on the basis of the 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 described by the sublattice models. A consistent set of thermodynamic parameters has been derived for describing the Gibbs free energies of each solution phase and intermetallic compounds in the Al-U and Co-U binary systems. The calculated phase diagrams and thermodynamic properties in the Al-U and Co-U systems are in good agreement with experimental data

Thermodynamic study of the A-B phase transition in superfluid 3He: Phase diagram and consequences

International Nuclear Information System (INIS)

Hahn, I.

1993-01-01

The authors have measured the A-B phase transition temperature of superfluid 3 He at pressures from zero to 29 bars, and in all magnetic fields up to the high field limit of the B phase (0.59 Tesla). This work is the first precision measurement of the A-B phase transition over the entire phase diagram (P, T, B). Measurements at low magnetic fields can be related to microscopic interactions in liquid 3 He. The results show that all current microscopic models of normal liquid 3 He are incomplete. Also, the results suggest the possibility that the conventional identification of the order parameter of superfluid 3 He-A is incorrect. The measurements at high magnetic fields can be related through thermodynamic identities to quantities which are immeasurable directly, such as the molar volume changes at the A-B phase transition, and the specific heat of the A-phase of superfluid 3 He in the limit T → 0. The authors detect the phase transition by monitoring the attenuation of zero around traversing a 4-mm path in the superfluid. Because thermometry is so crucial to the success of the measurements, the authors elected to use two independent thermometers. The authors use a pulsed NMR measurement of the susceptibility of Pt nuclei, which varies as 1/T, to guarantee linearity of the temperature scale. In order to achieve the high resolution required by the experiment, the authors also use an LCMN thermometer driven by a unique digital bridge which the authors constructed

Thermodynamics in the Suppressed Phase of the Madden-Julian Oscillation Using a Multiplatform Strategy

Science.gov (United States)

Roberts, J. Brent; Robertson, Franklin R.; Clayson, Carol Anne; Taylor, Patrick

2014-01-01

The Madden-Julian Oscillation (MJO) represents a prominent mode of intraseasonal tropical variability. It is manifest by coherent large-scale changes in atmospheric circulation, convection, and thermodynamic processes. Preconditioning of the environment prior to the active phase of the MJO has been noted, but the balance of theorized mechanisms to accomplish this process remains unresolved. Further, there is a lack of consensus on the means by which primary initiation of an MJO event occurs. Observational and modeling efforts have recently been undertaken to advance our understanding of the physical underpinnings governing MJO development. However these intensive studies are often limited in space and/or time and are potentially subject to model deficiencies. Satellite observations, especially those providing vertical resolution of temperature and moisture, provide an opportunity to expand our knowledge of processes critical to MJO initiation and preconditioning. This work will provide an analysis of suppressed phase thermodynamics with an emphasis on the use of a complementary suite of satellite observations including AIRS/AMSU-A profiles, CERES radiative fluxes, and cloud properties observed by MODIS. Emphasis of this work will regard the distribution of cloud regimes, their radiative-convective effects, and their relationship to moist static energy during the recharge and suppressed stages of MJO initiation and eastward propagation. The analyses will make use of cloud regimes from MODIS observations to provide a compositing technique that enables the identification of systematic connections between different cloud regimes and the larger scale environment. Within these cloud regimes, the relationship between the associated cloud-radiative effects observed by CERES, vertically-resolved and vertically-integrated thermodynamics using AIRS/AMSU-A observations, and atmospheric boundary layer fluxes will be demonstrated.

Thermodynamic database development: Al-Am-Ga-Pu-U

Energy Technology Data Exchange (ETDEWEB)

Perron, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Physical and Life Sciences; Turchi, P. E. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Physical and Life Sciences; Landa, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Physical and Life Sciences; Soderlind, P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Physical and Life Sciences

2014-03-17

The goal of this study is about the thermodynamic re-assessment of the Plutonium- Uranium (Pu-U) system as a first step leading to the development of a plutonium-based thermodynamic database (i.e., Pu with Al, Am, Ga, Mo, U…) with resulting phase diagrams and associated thermodynamic data. Indeed, phase stability trends and phase diagrams of multi-component nuclear materials are crucial for predicting properties and performance under normal, hypothetical or even accidental conditions. This work is based on a coupling between ab initio energetics, phenomenological thermodynamics models - based on the CALPHAD (CALculation of PHAse Diagrams) approach - and the use of the Thermo-Calc software, together with experimental data (whenever available). The present report summarizes results obtained (quarter period: 10/07/2013-01/07/2014) under the auspices of an agreement between CEA/DAM and NNSA/DP on cooperation in fundamental science supporting stockpile stewardship (P182).

Describing phase coexistence in systems with small phases

International Nuclear Information System (INIS)

Lovett, R

2007-01-01

Clusters of atoms can be studied in molecular beams and by computer simulation; 'liquid drops' provide elementary models for atomic nuclei and for the critical nuclei of nucleation theory. These clusters are often described in thermodynamic terms, but the behaviour of small clusters near a phase boundary is qualitatively different from the behaviour at a first order phase transition in idealized thermodynamics. In the idealized case the density and entropy show mathematically sharp discontinuities when the phase boundary is crossed. In large, but finite, systems, the phase boundaries become regions of state space wherein these properties vary rapidly but continuously. In small clusters with a large surface/volume ratio, however, the positive interfacial free energy makes it unlikely, even in states on phase boundaries, that a cluster will have a heterogeneous structure. What is actually seen in these states is a structure that fluctuates in time between homogeneous structures characteristic of the two sides of the phase boundary. That is, structural fluctuations are observed. Thermodynamics only predicts average properties; statistical mechanics is required to understand these fluctuations. Failure to distinguish thermodynamic properties and characterizations of fluctuations, particularly in the context of first order phase transitions, has led to suggestions that the classical rules for thermodynamic stability are violated in small systems and that classical thermodynamics provides an inconsistent description of these systems. Much of the confusion stems from taking statistical mechanical identifications of thermodynamic properties, explicitly developed for large systems, and applying them uncritically to small systems. There are no inconsistencies if thermodynamic properties are correctly identified and the distinction between thermodynamic properties and fluctuations is made clear

Thermodynamic assessment of the palladium-tellurium (Pd-Te) system

International Nuclear Information System (INIS)

Gosse, S.; Gueneau, C.

2011-01-01

Among the fission products formed in nuclear fuels, the platinum-group metal palladium and the chalcogen element tellurium exhibit strong interaction. It is therefore of interest to be able to predict the chemical equilibria involving the Pd and Te fission products. A thermodynamic assessment is carried out using the Calphad (Calculation of Phase Diagram) method to investigate the behaviour of Pd-Te alloy system in nuclear fuels under irradiation and under waste disposal conditions. The Pd-Te binary description was optimized using experimental data found in literature including thermodynamic properties and phase diagram data. To validate the calculated phase diagram and thermodynamic properties, the results are compared with data from the literature. Both calculated and experimental phase diagrams and thermodynamic properties are in good agreement in the whole Pd-Te composition range. (authors)

Constitution and thermodynamics of Pt-La alloys

International Nuclear Information System (INIS)

Reimann, S.; Schaller, H.-J.

2006-01-01

A complete set of thermodynamic functions was determined for the Pt-La system from electromotive force measurements on galvanic cells in the temperature range from 923 to 1073 K using CaF 2 single crystals as solid electrolytes. The phases on the platinum-rich side show pronounced negative deviations from ideal mixing behaviour; at 1073 K and infinite dilution, for instance, the relative partial excess Gibbs energy of La was determined to be -315 kJ/mol. Two effects are discussed to account for the deviations from ideal mixing behaviour: the transfer of the valence electrons of La to the electron gas of the alloy and the lattice distortion brought about by the size difference of the components. The phase relations were investigated by means of thermal, and X-ray analyses. The thermodynamic description of the system was optimized using experimental data from the present thermodynamic and phase diagram work. The calculated thermodynamic functions as well as the calculated phase diagram turned out to be in excellent accordance with the experimental results

Thermodynamic efficiency of nonimaging concentrators

Science.gov (United States)

Shatz, Narkis; Bortz, John; Winston, Roland

2009-08-01

The purpose of a nonimaging concentrator is to transfer maximal flux from the phase space of a source to that of a target. A concentrator's performance can be expressed relative to a thermodynamic reference. We discuss consequences of Fermat's principle of geometrical optics. We review étendue dilution and optical loss mechanisms associated with nonimaging concentrators, especially for the photovoltaic (PV) role. We introduce the concept of optical thermodynamic efficiency which is a performance metric combining the first and second laws of thermodynamics. The optical thermodynamic efficiency is a comprehensive metric that takes into account all loss mechanisms associated with transferring flux from the source to the target phase space, which may include losses due to inadequate design, non-ideal materials, fabrication errors, and less than maximal concentration. As such, this metric is a gold standard for evaluating the performance of nonimaging concentrators. Examples are provided to illustrate the use of this new metric. In particular we discuss concentrating PV systems for solar power applications.

New phases of thermal SYM and LST from Kaluza-Klein black holes

DEFF Research Database (Denmark)

Harmark, Troels; Obers, Niels A.

2005-01-01

between phases of Kaluza-Klein black holes and the thermodynamic behavior of the non-gravitational theories dual to near-extremal branes on a circle. In particular, for the thermodynamics of strongly-coupled supersymmetric Yang-Mills theories on a circle we predict the existence of a new non-uniform phase......We review the recently found map that takes any static and neutral Kaluza-Klein black hole, i.e. any static and neutral black hole on Minkowski-space times a circle Md × S1, and maps it to a corresponding solution for a non- and near-extremal brane on a circle. This gives a precise connection...... and find new information about the localized phase. We also find evidence for the existence of a new stable phase of (2, 0) Little String Theory in the canonical ensemble for temperatures above its Hagedorn temperature....

Phase selection and microstructure in directional solidification of glass forming Pd-Si-Cu alloys

Science.gov (United States)

Huo, Yang

Phase selection and microstructure formation during the rapid solidification of alloy melts has been a topic of substantial interest over the last several decades, attributed mainly to the access to novel structures involving metastable crystalline and non-crystalline phases. In this work, Bridgeman type directional solidification was conducted in Pd-Si-Cu glass forming system to study such cooling rate dependent phase transition and microstructure formation. The equilibrium state for Pd-Si-Cu ternary system was investigated through three different works. First of all, phase stabilities for Pd-Si binary system was accessed with respects of first-principles and experiments, showing Pd5Si, Pd9Si2, Pd3Si and Pd 2Si phase are stable all way to zero Kevin while PdSi phase is a high temperature stable phase, and Pd2Si phase with Fe2P is a non-stoichiometry phase. A thermodynamic database was developed for Pd-Si system. Second, crystal structures for compounds with ternary compositions were studied by XRD, SEM and TEM, showing ordered and disordered B2/bcc phases are stable in Pd-rich part. At last, based on many phase equilibria and phase transitions data, a comprehensive thermodynamic discrption for Pd-Si-Cu ternary system was first time to be developed, from which different phase diagrams and driving force for kinetics can be calculated. Phase selection and microstructure formation in directional solidification of the best glass forming composition, Pd 77.5Si16.5Cu6, in this system with growth velocities from 0.005 to 7.5mm/s was systematically studied and the solidification pathways at different conditions were interpreted from thermodynamic simulation. The results show that for growth velocities are smaller than 0.1mm/s Pd 3Si phase is primary phase and Pd9Si2 phase is secondary phase, the difficulty for Pd9Si2 phase nucleation gives rise to the formation of two different eutectic structure. For growth velocities between 0.4 and 1mm/s, instead of Pd3Si phase, Pd9Si2

Thermodynamic Geometry and Hawking Radiation

CERN Document Server

Bellucci, S

2010-01-01

This work explores the role of thermodynamic fluctuations in the two parameter Hawking radiating black hole configurations. The system is characterized by an ensemble of arbitrary mass and radiation frequency of the black holes. In the due course of the Hawking radiations, we find that the intrinsic geometric description exhibits an intriguing set of exact pair correction functions and global correlation lengths. We investigate the nature of the constant amplitude radiation and find that it's not stable under fluctuations of the mass and frequency. Subsequently, the consideration of the York model decreasing amplitude radiation demonstrates that thermodynamic fluctuations are globally stable in the small frequency region. In connection with quantum gravity refinements, we take an account of the logarithmic correction into the constant amplitude and York amplitude over the Hawking radiation. In both considerations, we notice that the nature of the possible parametric fluctuations may precisely be ascertained w...

Thermodynamics of Accelerating Black Holes.

Science.gov (United States)

Appels, Michael; Gregory, Ruth; Kubizňák, David

2016-09-23

We address a long-standing problem of describing the thermodynamics of an accelerating black hole. We derive a standard first law of black hole thermodynamics, with the usual identification of entropy proportional to the area of the event horizon-even though the event horizon contains a conical singularity. This result not only extends the applicability of black hole thermodynamics to realms previously not anticipated, it also opens a possibility for studying novel properties of an important class of exact radiative solutions of Einstein equations describing accelerated objects. We discuss the thermodynamic volume, stability, and phase structure of these black holes.

Towards a thermodynamics of active matter.

Science.gov (United States)

Takatori, S C; Brady, J F

2015-03-01

Self-propulsion allows living systems to display self-organization and unusual phase behavior. Unlike passive systems in thermal equilibrium, active matter systems are not constrained by conventional thermodynamic laws. A question arises, however, as to what extent, if any, can concepts from classical thermodynamics be applied to nonequilibrium systems like active matter. Here we use the new swim pressure perspective to develop a simple theory for predicting phase separation in active matter. Using purely mechanical arguments we generate a phase diagram with a spinodal and critical point, and define a nonequilibrium chemical potential to interpret the "binodal." We provide a generalization of thermodynamic concepts like the free energy and temperature for nonequilibrium active systems. Our theory agrees with existing simulation data both qualitatively and quantitatively and may provide a framework for understanding and predicting the behavior of nonequilibrium active systems.

Solvation thermodynamics of phenylalcohols in lamellar phase surfactant dispersions

International Nuclear Information System (INIS)

Martyniak, A.; Scheuermann, R.; Dilger, H.; Tucker, I.M.; Burkert, T.; Hashmi, A.S.K.; Vujosevic', D.; Roduner, E.

2006-01-01

The distribution and the stability of five phenylalcohols in a lamellar phase composed of simple bilayers separated by water at 298 and 348K is explored using avoided-level-crossing muon-spin resonance (ALC-μSR). The dependence of the alignment of the bilayer chains on temperature appears to be a crucial factor determining the phenylalcohol partitioning: increasing order of the surfactant tails leads to expulsion of the solute. Moreover, we observed a systematic trend, the longer the chain the deeper the phenyl group dips into the lipid bilayer. Recent studies have shown that the hydrophobic effect is adequate to describe membrane partitioning of small amphiphilic molecules. The solvation thermodynamic properties ΔG sol , ΔH sol , and ΔS sol which determine the solute transfer from the double layer into water prove that the distribution also strongly depends on shape, chemical nature and different structure of phenylalcohols

Solvation thermodynamics of phenylalcohols in lamellar phase surfactant dispersions

Energy Technology Data Exchange (ETDEWEB)

Martyniak, A. [Institut fuer Physikalische Chemie, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany); Scheuermann, R. [Laboratory for muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen (Switzerland); Dilger, H. [Institut fuer Physikalische Chemie, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany); Tucker, I.M. [Unilever Research and Development, Port Sunlight, Wirral CH63 3JW (United Kingdom); Burkert, T. [Institut fuer Organische Chemie, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany); Hashmi, A.S.K. [Institut fuer Organische Chemie, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany); Vujosevic' , D. [Institut fuer Physikalische Chemie, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany); Roduner, E. [Institut fuer Physikalische Chemie, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany)]. E-mail: e.roduner@ipc.uni-stuttgart.de

2006-03-31

The distribution and the stability of five phenylalcohols in a lamellar phase composed of simple bilayers separated by water at 298 and 348K is explored using avoided-level-crossing muon-spin resonance (ALC-{mu}SR). The dependence of the alignment of the bilayer chains on temperature appears to be a crucial factor determining the phenylalcohol partitioning: increasing order of the surfactant tails leads to expulsion of the solute. Moreover, we observed a systematic trend, the longer the chain the deeper the phenyl group dips into the lipid bilayer. Recent studies have shown that the hydrophobic effect is adequate to describe membrane partitioning of small amphiphilic molecules. The solvation thermodynamic properties {delta}G{sub sol}, {delta}H{sub sol}, and {delta}S{sub sol} which determine the solute transfer from the double layer into water prove that the distribution also strongly depends on shape, chemical nature and different structure of phenylalcohols.

Thermodynamic modeling of the Sr-Co-Fe-O system

DEFF Research Database (Denmark)

Zhang, Wei Wei; Povoden-Karadeniz, Erwin; Chen, Ming

2016-01-01

This paper reviews and assesses phase equilibria and thermodynamic properties of phases in the Sr-Co-Fe-O system, with a focus on oxides, especially the SrCo1 - xFexO3 - δ perovskite. In our work, the SrCo1 - xFexO3 - δ perovskite was modeled with a three-sublattice model, where the three...... sublattices correspond to the A, B and oxygen sites in an ABO3 perovskite, respectively. A number of other important ternary oxide phases in Sr-Co-O and Sr-Co-Fe-O were also considered. Available thermodynamic and phase diagram data were carefully assessed. A thermodynamic description of Sr-Co-O was derived...

Thermodynamic stability and kinetic dissolution of perovskite in natural waters

International Nuclear Information System (INIS)

Nesbitt, H.W.; Bancroft, G.M.; Fyfe, W.S.; Karkhanis, S.; Melling, P.; Nishijima, A.

1981-01-01

Ringwood and coworkers have recently proposed using titanates and zirconates as hosts for nuclear waste in the Synroc B process. Three minerals are used as hosts: perovskite (CaTiO 3 ), Ba-hollandite (BaAl 2 Ti 6 O 16 ), and zirconolite (CaZrTi 2 O 7 ). The Synroc philosophy relies heavily on geological and geochemical observations in selecting stable host minerals. Although it has been recognized that the Synroc minerals are not thermodynamically compatible with siliceous rocks, the minerals are considered to be thermodynamically stable in the presence of water, and it has been reported that these minerals are kinetically stable under high-temperature (up to 900 0 C) hydrothermal conditions. Detailed thermodynamic calculations and leach tests have been performed which demonstrate: first, that perovskite is thermodynamically unstable in all known natural waters; and second, that pervoskite leaches at a significant rate even at 100 0 C. Hydrothermal leach tests have been made on natural and synthetic perovskite and perovskite analogues between 100 0 C and 300 0 C. Weight losses and solution concentrations were monitored. The results reported previously in the literature also show that perovskite is kinetically unstable in the presence of common silicates. Our results show that perovskite may be no more stable than siliceous glasses, such as rhyolite, which have been studied previously. Geologic evidence from common alkaline rocks also indicates that hollandite and zirconolite probably will not survive in common rock matrices

Thermodynamically consistent modeling and simulation of multi-component two-phase flow with partial miscibility

KAUST Repository

Kou, Jisheng

2017-12-09

A general diffuse interface model with a realistic equation of state (e.g. Peng-Robinson equation of state) is proposed to describe the multi-component two-phase fluid flow based on the principles of the NVT-based framework which is an attractive alternative recently over the NPT-based framework to model the realistic fluids. The proposed model uses the Helmholtz free energy rather than Gibbs free energy in the NPT-based framework. Different from the classical routines, we combine the first law of thermodynamics and related thermodynamical relations to derive the entropy balance equation, and then we derive a transport equation of the Helmholtz free energy density. Furthermore, by using the second law of thermodynamics, we derive a set of unified equations for both interfaces and bulk phases that can describe the partial miscibility of multiple fluids. A relation between the pressure gradient and chemical potential gradients is established, and this relation leads to a new formulation of the momentum balance equation, which demonstrates that chemical potential gradients become the primary driving force of fluid motion. Moreover, we prove that the proposed model satisfies the total (free) energy dissipation with time. For numerical simulation of the proposed model, the key difficulties result from the strong nonlinearity of Helmholtz free energy density and tight coupling relations between molar densities and velocity. To resolve these problems, we propose a novel convex-concave splitting of Helmholtz free energy density and deal well with the coupling relations between molar densities and velocity through very careful physical observations with a mathematical rigor. We prove that the proposed numerical scheme can preserve the discrete (free) energy dissipation. Numerical tests are carried out to verify the effectiveness of the proposed method.

Thermodynamic modeling of the Ce-Zn and Pr-Zn systems

International Nuclear Information System (INIS)

Wang, C.P.; Chen, X.; Liu, X.J.; Pan, F.S.; Ishida, K.

2008-01-01

In order to develop the thermodynamic database of phase equilibria in the Mg-Zn-Re (Re: rare earth element) base alloys, the thermodynamic assessments of the Ce-Zn and Pr-Zn systems were carried out by using the calculation of phase diagrams (CALPHAD) method on the basis of the experimental data including thermodynamic properties and phase equilibria. Based on the available experimental data, Gibbs free energies of the solution phases (liquid, bcc, fcc, hcp and dhcp) were modeled by the subregular solution model with the Redlich-Kister formula, and those of the intermetallic compounds were described by the sublattice model. A consistent set of thermodynamic parameters has been derived for describing the Gibbs free energies of each solution phase and intermetallic compound in the Ce-Zn and Pr-Zn binary systems. An agreement between the present calculated results and experimental data is obtained

Corundum-to-spinel structural phase transformation in alumina

Energy Technology Data Exchange (ETDEWEB)

Adachi, Shogo [Department of Materials Science and Engineering, Kyushu Institute of Technology, Fukuoka 804-8550 (Japan); Ishimaru, Manabu, E-mail: ishimaru@post.matsc.kyutech.ac.jp [Department of Materials Science and Engineering, Kyushu Institute of Technology, Fukuoka 804-8550 (Japan); Sina, Younes; McHargue, Carl J.; Sickafus, Kurt E. [Materials Science and Engineering Department, University of Tennessee, Knoxville, TN 37996-2200 (United States); Alves, Eduardo [Unit of Physics and Accelerators, Ion Beam Laboratory, Instituto Superior Técnico/Instituto Tecnológico e Nuclear, EN. 10 2686-953 Sacavém (Portugal)

2015-09-01

Several polymorphs exist in alumina (Al{sub 2}O{sub 3}), and they transform to a stable α-phase with a hexagonal corundum structure on thermal annealing. This structural change is irreversible as a function of temperature, and transformation of corundum to another metastable crystalline phase has never been observed by heat treatments. In this study, we irradiated single crystals of Al{sub 2}O{sub 3} with Zr ions and obtained an irradiated microstructure consisting of a buried α-Al{sub 2}O{sub 3} layer surrounded on top and bottom by layers of a defect cubic spinel Al{sub 2}O{sub 3} phase. We examined the thermal stability of this microstructure using transmission electron microscopy and X-ray diffraction. We found that the corundum phase completely transforms to the spinel phase following annealing at 1173 K for 1 h: the thermodynamically stable phase transforms to the metastable phase by heat treatments. We discuss this unusual structural change within the context of our results as well as previous observations.

Kinematics and thermodynamics of non-stoichiometric oxidation phase transitions in spent fuel

International Nuclear Information System (INIS)

Stout, R.B.; Kansa, E.J.; Wijesinghe, A.M.

1993-01-01

At low temperatures ( 2 lattice to a U 4 O 9 lattice but with an oxygen-to-uranium (O/U) ratio of ∼2.4. Also, the weight gain time response has a plateau as the O/U approaches 2.4. Part of this response results from a geometrical dependency as a U 4 O 9 oxidation front propagates into grain volumes Of UO 2 It may also be indicative of a metastable, non-stoichiometric U 4 O 9 phase whose existence may inhibit the transition kinetics to the next expected phase Of U 3 O 8 . To gain a mechanistic understanding and to plan future oxidation tests, lattice kinematic and thermodynamic models are developed for lattice deformations and energetics of lattice phase changes (UO 2 → U 4 O 9 → U 3 0 7 → U 3 O 8) that include zeroth order influences on oxidation kinetics due to interstitial oxygen atoms and vacancies plus interstitial and substitutional actinides and fission decay products in spent fuel

Phase behaviour and thermodynamic modelling for the system (grape seed oil + carbon dioxide + ethanol) at high pressures

International Nuclear Information System (INIS)

Dalmolin, Irede; Rigo, Aline A.; Corazza, Marcos L.; Ndiaye, Papa M.; Meireles, M. Angela A.; Batista, Eduardo A.C.; Oliveira, J. Vladimir

2014-01-01

This short communication reports phase equilibrium data (cloud points), employing the synthetic static method, for the system {grape seed oil (GSO) + carbon dioxide (CO 2 ) + ethanol} up to T = 343.15 K and 22.53 MPa. Experimental results were modelled using the Peng-Robinson equation of state with the classical van der Waals quadratic mixing rule (PR-vdW2). It is shown that the thermodynamic model is able to represent satisfactorily the phase behaviour of the system investigated

Preparation and properties of lauric acid/silicon dioxide composites as form-stable phase change materials for thermal energy storage

International Nuclear Information System (INIS)

Fang Guiyin; Li Hui; Liu Xu

2010-01-01

Form-stable lauric acid (LA)/silicon dioxide (SiO 2 ) composite phase change materials were prepared using sol-gel methods. The LA was used as the phase change material for thermal energy storage, with the SiO 2 acting as the supporting material. The structural analysis of these form-stable LA/SiO 2 composite phase change materials was carried out using Fourier transformation infrared spectroscope (FT-IR). The microstructure of the form-stable composite phase change materials was observed by a scanning electronic microscope (SEM). The thermal properties and thermal stability were investigated by a differential scanning calorimeter (DSC) and a thermogravimetric analysis apparatus (TGA), respectively. The SEM results showed that the LA was well dispersed in the porous network of SiO 2 . The DSC results indicated that the melting latent heat of the form-stable composite phase change material is 117.21 kJ kg -1 when the mass percentage of the LA in the SiO 2 is 64.8%. The results of the TGA showed that these materials have good thermal stability. The form-stable composite phase change materials can be used for thermal energy storage in waste heat recovery and solar heating systems.

Phase equilibrium, crystallization behavior and thermodynamic studies of (m-dinitrobenzene + vanillin) eutectic system

International Nuclear Information System (INIS)

Singh, Jayram; Singh, N.B.

2015-01-01

Graphical abstract: The phase diagram of (m-dinitrobenzene + vanillin) system. - Highlights: • (Thaw + melt) method has shown that (m-dinitrobenzene + vanillin) system forms simple eutectic type phase diagram. • Excess thermodynamic functions showed that eutectic mixture is non-ideal. • The flexural strength measurements have shown that in eutectic mixture, crystallization occurs in an ordered way. - Abstract: The phase diagram of (m-dinitrobenzene + vanillin) system has been studied by the thaw melt method and an eutectic type phase diagram was obtained. The linear velocities of crystallization of the parent components and the eutectic mixture were determined. The enthalpy of fusion of the components and the eutectic mixture were determined using the differential scanning calorimetric technique. Excess Gibbs energy, excess entropy, excess enthalpy of mixing, and interfacial energy have been calculated. FTIR spectroscopic studies and flexural strength measurements were also made. The results have shown that the eutectic is a non-ideal mixture of the two components. On the basis of Jackson’s roughness parameter, it is predicted that the eutectic has faceted morphology

Novel phases of lithium-aluminum binaries from first-principles structural search

Energy Technology Data Exchange (ETDEWEB)

Sarmiento-Pérez, Rafael; Cerqueira, Tiago F. T.; Botti, Silvana; Marques, Miguel A. L., E-mail: marques@tddft.org [Institut Lumière Matière (UMR5306) and ETSF, Université Lyon 1-CNRS, Université de Lyon, F-69622 Villeurbanne Cedex (France); Valencia-Jaime, Irais [Institut Lumière Matière (UMR5306) and ETSF, Université Lyon 1-CNRS, Université de Lyon, F-69622 Villeurbanne Cedex (France); Centro de Investigación y Estudios Avanzados del IPN, MX-76230 Querétaro (Mexico); Amsler, Maximilian; Goedecker, Stefan [Department of Physics, Universität Basel, Klingelbergstr. 82, 4056 Basel (Switzerland); Romero, Aldo H. [Physics Department, West Virginia University, Morgantown, West Virginia 26506-6315 (United States)

2015-01-14

Intermetallic Li–Al compounds are on the one hand key materials for light-weight engineering, and on the other hand, they have been proposed for high-capacity electrodes for Li batteries. We determine from first-principles the phase diagram of Li–Al binary crystals using the minima hopping structural prediction method. Beside reproducing the experimentally reported phases (LiAl, Li{sub 3}Al{sub 2}, Li{sub 9}Al{sub 4}, LiAl{sub 3}, and Li{sub 2}Al), we unveil a structural variety larger than expected by discovering six unreported binary phases likely to be thermodynamically stable. Finally, we discuss the behavior of the elastic constants and of the electric potential profile of all Li–Al stable compounds as a function of their stoichiometry.

Thermodynamic modelling and in-situ neutron diffraction investigation of the (Ce + Mg + Zn) system

International Nuclear Information System (INIS)

Zhu, Zhijun; Gharghouri, Michael A.; Medraj, Mamoun; Lee, Soo Yeol; Pelton, Arthur D.

2016-01-01

Highlights: • All phase diagram and thermodynamic data critically assessed for the (Ce + Mg + Zn) system. • All phases described by optimized thermodynamic models. • In-situ neutron diffraction performed to identify phases and transition temperatures. • Assessments of other (RE + Mg + Zn) systems have been carried out simultaneously. • The final product is a thermodynamic database for multicomponent (Mg + RE + Zn) systems. - Abstract: All available phase diagram data for the (Ce + Mg + Zn) system were critically assessed. In-situ neutron diffraction (ND) experiments were performed on selected samples to identify phases and transition temperatures. A critical thermodynamic evaluation and optimization of the (Ce + Mg + Zn) system were carried out and model parameters for the thermodynamic properties of all phases were obtained. The phase transformation behaviour of selected samples was well resolved from the ND experiments and experimental data were used to refine the thermodynamic model parameters.

Unconditionally stable methods for simulating multi-component two-phase interface models with Peng-Robinson equation of state and various boundary conditions

KAUST Repository

Kou, Jisheng

2015-03-01

In this paper, we consider multi-component dynamic two-phase interface models, which are formulated by the Cahn-Hilliard system with Peng-Robinson equation of state and various boundary conditions. These models can be derived from the minimum problems of Helmholtz free energy or grand potential in the realistic thermodynamic systems. The resulted Cahn-Hilliard systems with various boundary conditions are fully coupled and strongly nonlinear. A linear transformation is introduced to decouple the relations between different components, and as a result, the models are simplified. From this, we further propose a semi-implicit unconditionally stable time discretization scheme, which allows us to solve the Cahn-Hilliard system by a decoupled way, and thus, our method can significantly reduce the computational cost and memory requirements. The mixed finite element methods are employed for the spatial discretization, and the approximate errors are also analyzed for both space and time. Numerical examples are tested to demonstrate the efficiency of our proposed methods. © 2015 Elsevier B.V.

First principles thermodynamics of alloys

International Nuclear Information System (INIS)

Ducastelle, F.

1993-01-01

We present a brief report on the methods of solid state physics (electronic structure, statistical thermodynamics) that allow us to discuss the phase stability of alloys and to determine their phase diagrams. (orig.)

Thermodynamic assessment of the Pb-Sr system

Directory of Open Access Journals (Sweden)

Zhang H.

2017-01-01

Full Text Available The Pb-Sr system has been critically reviewed and modeled by means of the CALPHAD (CALculation of PHAse Diagrams approach. It contains seven stoichiometric compounds, i.e. SrPb3, Sr3Pb5, Sr2Pb3, SrPb, Sr5Pb4, Sr5Pb3 and Sr2Pb, in which the SrPb3 and Sr2Pb phases melt congruently, and the other five phases form via peritectic reactions. The enthalpies of formation for the intermetallic compounds at 0 K are provided by first-principles calculations. The liquid, fcc and bcc phases are modeled as substitutional solution phases. Both Redlich-Kister and exponential polynomials are used to describe the excess Gibbs energy of the liquid. Two sets of self-consistent thermodynamic parameters are obtained by considering reliable experimental data and the computed enthalpies of formation. Comprehensive comparisons between the calculated and measured phase diagram and thermodynamic data show that the experimental information is satisfactorily accounted for by the present thermodynamic description.

Thermodynamic Stability of Ice II and Its Hydrogen-Disordered Counterpart: Role of Zero-Point Energy.

Science.gov (United States)

Nakamura, Tatsuya; Matsumoto, Masakazu; Yagasaki, Takuma; Tanaka, Hideki

2016-03-03

We investigate why no hydrogen-disordered form of ice II has been found in nature despite the fact that most of hydrogen-ordered ices have hydrogen-disordered counterparts. The thermodynamic stability of a set of hydrogen-ordered ice II variants relative to ice II is evaluated theoretically. It is found that ice II is more stable than the disordered variants so generated as to satisfy the simple ice rule due to the lower zero-point energy as well as the pair interaction energy. The residual entropy of the disordered ice II phase gradually compensates the unfavorable free energy with increasing temperature. The crossover, however, occurs at a high temperature well above the melting point of ice III. Consequently, the hydrogen-disordered phase does not exist in nature. The thermodynamic stability of partially hydrogen-disordered ices is also scrutinized by examining the free-energy components of several variants obtained by systematic inversion of OH directions in ice II. The potential energy of one variant is lower than that of the ice II structure, but its Gibbs free energy is slightly higher than that of ice II due to the zero-point energy. The slight difference in the thermodynamic stability leaves the possibility of the partial hydrogen-disorder in real ice II.

Thermodynamic modeling of the insoluble phases in the nuclear waste glasses. Application to the vitrification of molybdenum and of platinoid fission products

International Nuclear Information System (INIS)

Bordier, Sebastien

2015-01-01

After the dissolution of the used fuel and the separation of several elements by the Purex process, the high level nuclear wastes composed of fission products and minor actinides are reprocessed and vitrified in nuclear glasses at AREVA La Hague plant. Some of the fission products precipitate: they are not solubilized in the glass matrix. On the one hand, depending on the oxygen potential of the glass melt, the platinoid elements Pd-Ru-Rh form complex solid oxide phases or intermetallic compounds containing chalcogen elements such as selenium and tellurium. On the other hand, the molybdenum forms only oxide phases. It reacts strongly with the oxide phases present in the glass melt to form molybdate phases able to solubilise other elements like lanthanides. These phases can locally precipitate for a high load in molybdenum. Nevertheless, the formation of the molybdate phases has to remain transient. In this thesis, the thermodynamics of the chemical Systems containing the platinoid elements Pd-Rh-Ru and the chalcogen elements Se and Te were experimentally investigated. The Systems containing the platinoids were studied by DTA, DSC, Tian-Calvet drop calorimetry and by annealing. For the Systems containing the molybdenum, the interactions between MoO_3 and the main oxides composing the glass (Na_2O, SiO_2, MoO_3 and CaO) were studied by high temperature XRD. In the meantime, the thermodynamics of these chemical Systems was modeled with the Calphad method so as to be able to predict the crystallization phenomena of molybdenum and of the platinoids. The ternary Systems Ru-Rh-O and Pd-Se-Te were optimized to understand the platinoids thermochemistry. The Systems CaO-MoO_3, Na_2O-MoO_3 and Na_2MoO_4-CaMoO_4 were modeled to assess the thermodynamics of the molybdate phases. Moreover, the Systems Na_20 - SiO_2 and Na_2O-SiO_2-MoO_3 were optimized to describe the interaction between the molybdate phases and the glass melt. These modelling allow to perform application

Some consideration on the thermodynamics of the universe

International Nuclear Information System (INIS)

Hoenl, H.

1977-01-01

It is shown that the thermodynamics of the universe display certain features that are foreign to classical thermodynamics, the discrepancy having its origin in the cosmic expansion of the universe. This is apparent, for example, in the outstanding fact that in the early stages of the universe (some 10 5 or 10 6 years after the Big Bang) the distribution of matter was essentially homogeneous and, owing to the extremely high density and temperature, was in thermodynamic equilibrium. However, in its present state, after the formation of the celestial bodies, (the inhomogeneous phase of the universe), it has moved far away from thermodynamic equilibrium. It is stated that to prove entropy conservation during the homogeneous phase of the universe, one only needs the most general thermodynamical-statistical principles. (U,K)

Thermodynamics of rotating black branes in gravity with first order string corrections

Directory of Open Access Journals (Sweden)

M. H. Dehghani

2005-09-01

Full Text Available   In this paper, the rotating black brane solutions with zero curvature horizon of classical gravity with first order string corrections are introduced. Although these solutions are not asymptotically anti de Sitter, one can use the counterterm method in order to compute the conserved quantities of these solutions. Here, by reviewing the counterterm method for asymptotically anti de Sitter spacetimes, the conserved quantities of these rotating solutions are computed. Also a Smarr-type formula for the mass as a function of the entropy and the angular momenta is obtained, and it is shown that the conserved and thermodynamic quantities satisfy the first law of thermodynamics. Finally, a stability analysis in the canonical ensemble is performed, and it is shown that the system is thermally stable. This is in commensurable with the fact that there is no Hawking-Page phase transition for black object with zero curvature horizon.

Statistical Thermodynamics and Microscale Thermophysics

Science.gov (United States)

Carey, Van P.

1999-08-01

Many exciting new developments in microscale engineering are based on the application of traditional principles of statistical thermodynamics. In this text Van Carey offers a modern view of thermodynamics, interweaving classical and statistical thermodynamic principles and applying them to current engineering systems. He begins with coverage of microscale energy storage mechanisms from a quantum mechanics perspective and then develops the fundamental elements of classical and statistical thermodynamics. Subsequent chapters discuss applications of equilibrium statistical thermodynamics to solid, liquid, and gas phase systems. The remainder of the book is devoted to nonequilibrium thermodynamics of transport phenomena and to nonequilibrium effects and noncontinuum behavior at the microscale. Although the text emphasizes mathematical development, Carey includes many examples and exercises to illustrate how the theoretical concepts are applied to systems of scientific and engineering interest. In the process he offers a fresh view of statistical thermodynamics for advanced undergraduate and graduate students, as well as practitioners, in mechanical, chemical, and materials engineering.

Thermodynamic variables of first-order entropy corrected Lovelock-AdS black holes: P{-}V criticality analysis

Science.gov (United States)

Haldar, Amritendu; Biswas, Ritabrata

2018-06-01

We investigate the effect of thermal fluctuations on the thermodynamics of a Lovelock-AdS black hole. Taking the first order logarithmic correction term in entropy we analyze the thermodynamic potentials like Helmholtz free energy, enthalpy and Gibbs free energy. We find that all the thermodynamic potentials are decreasing functions of correction coefficient α . We also examined this correction coefficient must be positive by analysing P{-}V diagram. Further we study the P{-}V criticality and stability and find that presence of logarithmic correction in it is necessary to have critical points and stable phases. When P{-}V criticality appears, we calculate the critical volume V_c, critical pressure P_c and critical temperature T_c using different equations and show that there is no critical point for this black hole without thermal fluctuations. We also study the geometrothermodynamics of this kind of black holes. The Ricci scalar of the Ruppeiner metric is graphically analysed.

Thermodynamics and statistical mechanics. [thermodynamic properties of gases

Science.gov (United States)

1976-01-01

The basic thermodynamic properties of gases are reviewed and the relations between them are derived from the first and second laws. The elements of statistical mechanics are then formulated and the partition function is derived. The classical form of the partition function is used to obtain the Maxwell-Boltzmann distribution of kinetic energies in the gas phase and the equipartition of energy theorem is given in its most general form. The thermodynamic properties are all derived as functions of the partition function. Quantum statistics are reviewed briefly and the differences between the Boltzmann distribution function for classical particles and the Fermi-Dirac and Bose-Einstein distributions for quantum particles are discussed.

Thermodynamic reassessment of the neodymium–gold binary system

Energy Technology Data Exchange (ETDEWEB)

Moustaine, D., E-mail: mostainedris@gmail.com; Mahdouk, K.

2016-07-15

Phase relationships in Nd–Au binary system have been thermodynamically assessed by means of the CALPHAD technique through Thermo–Calc software package based on the experiment information of phase equilibria and thermodynamic properties from the published literature data. The excess Gibbs energy functions of the solution phases including liquid, fcc-A1, bcc-A2, and dhcp were formulated with Redlich–Kister polynomial functions. The two–sublattice energy model was employed to describe the Nd{sub 14}Au{sub 51} phase which exhibits a homogeneity range. The intermetallic compounds Nd{sub 2}Au, NdAu, Nd{sub 3}Au{sub 4}, Nd{sub 17}Au{sub 36}, and NdAu{sub 6} were treated as stoichiometric phases. A set of self-consistent thermodynamic parameters formulating the Gibbs energy of various phases in the Nd–Au binary system were then obtained. A much better agreement was achieved between the calculated results and the reported experimental data. - Highlights: • The Nd–Au has been re-assessed using the latest experimental results. • The intermetallic compound Nd{sub 14}Au{sub 51} was treated by a two–sublattice model. • The errors of related modelling presented in previous articles have been modified. • A self–consistent thermodynamic description of the Nd–Au system was obtained.

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

Thermodynamic properties of a quasi-harmonic model for ferroelectric transitions

International Nuclear Information System (INIS)

Mkam Tchouobiap, S E; Mashiyama, H

2011-01-01

Within a framework of a quasi-harmonic model for quantum particles in a local potential of the double Morse type and within the mean-field approximation for interactions between particles, we investigate the thermodynamic properties of ferroelectric materials. A quantum thermodynamic treatment gives analytic expressions for the internal energy, the entropy, the specific heat, and the static susceptibility. The calculated thermodynamic characteristics are studied as a function of temperature and energy barrier, where it is shown that at the proper choice of the theory parameters, particularly the energy barrier, the model system exhibits characteristic features of either second-order tricritical or first-order phase transitions. Our results indicate that the barrier energy seems to be an important criterion for the character of the structural phase transition. The influence of quantum fluctuations manifested on zero-point energy on the phase transition and thermodynamic properties is analyzed and discussed. This leads to several quantum effects, including the existence of a saturation regime at low temperatures, where the order parameter saturates giving thermodynamic saturation of the calculated thermodynamic quantities. It is found that both quantum effects and energy barrier magnitude have an important influence on the thermodynamic properties of the ferroelectric materials and on driving the phase transition at low temperatures. Also, the analytical parameters' effect on the transition temperature is discussed, which seems to give a general insight into the structural phase transition and its nature.

Intrinsically stable phase-modulated polarization encoding system for quantum key distribution

Energy Technology Data Exchange (ETDEWEB)

Liu Xiaobao [Laboratory of Photonic Information Technology, School for Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006 (China); Liao Changjun [Laboratory of Photonic Information Technology, School for Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006 (China)], E-mail: chliao@scnu.edu.cn; Mi Jinglong; Wang Jindong; Liu Songhao [Laboratory of Photonic Information Technology, School for Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006 (China)

2008-12-22

We demonstrate experimentally an intrinsically stable polarization coding and decoding system composed of optical-fiber Sagnac interferometers with integrated phase modulators for quantum key distribution. An interference visibility of 98.35% can be kept longtime during the experiment without any efforts of active compensation for coding all four desired polarization states.

Thermodynamic and kinetic simulation of transient liquid-phase bonding

Science.gov (United States)

Lindner, Brad

The use of numeric computational methods for the simulation of materials systems is becoming more prevalent and an understanding of these tools may soon be a necessity for Materials Engineers and Scientists. The applicability of numerical simulation methods to transient liquid-phase (TLP) bonding is evaluated using a type 316L/MBF-51 material system. The comparisons involve the calculation of bulk diffusivities, tracking of interface positions during dissolution, widening, and isothermal solidification stages, as well as comparison of elemental composition profiles. The simulations were performed with Thermo-Calc and DICTRA software packages and the experiments with differential scanning calorimetry (DSC), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and optical microscopic methods. Analytical methods are also discussed to enhance understanding. The results of the investigation show that while general agreement between simulations and experiments can be obtained, assumptions made with the simulation programs may cause difficulty in interpretation of the results unless the user has sufficient, mathematical, thermodynamic, kinetic, and simulation background.

Thermodynamic modeling of the Mg-Al-Ca system

Energy Technology Data Exchange (ETDEWEB)

Janz, A.; Groebner, J. [Clausthal University of Technology, Institute of Metallurgy, Robert-Koch-Str. 42, D-38678 Clausthal-Zellerfeld (Germany); Cao, H.; Zhu, J.; Chang, Y.A. [Department of Materials Science and Engineering, University of Wisconsin, 1509 University Ave., Madison, WI 53706 (United States); Schmid-Fetzer, R. [Clausthal University of Technology, Institute of Metallurgy, Robert-Koch-Str. 42, D-38678 Clausthal-Zellerfeld (Germany)], E-mail: schmid-fetzer@tu-clausthal.de

2009-02-15

A thermodynamic model has been developed that provides a quantitative description for a wide area of the Mg-Al-Ca system. All available experimental data plus new key experiments using differential scanning calorimetry/differential thermal analysis have been considered to create a dataset which reproduces the primary crystallizing phases, the extensive ternary solubilities of binary phases and the ternary C36 Laves phase. This enables validated thermodynamic calculations in various areas of this ternary system.

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

Ch. 33 Modeling: Computational Thermodynamics

International Nuclear Information System (INIS)

Besmann, Theodore M.

2012-01-01

This chapter considers methods and techniques for computational modeling for nuclear materials with a focus on fuels. The basic concepts for chemical thermodynamics are described and various current models for complex crystalline and liquid phases are illustrated. Also included are descriptions of available databases for use in chemical thermodynamic studies and commercial codes for performing complex equilibrium calculations.

Aerosol Particle Interfacial Thermodynamics and Phase Partitioning Measurements Using Biphasic Microfluidics

Science.gov (United States)

Dutcher, Cari; Metcalf, Andrew

2015-03-01

Secondary organic aerosol particles are nearly ubiquitous in the atmosphere and yet there remain large uncertainties in their formation processes and ambient properties. These particles are complex microenvironments, which can contain multiple interfaces due to internal aqueous-organic phase partitioning and to the external liquid-vapor surface. Interfacial properties affect the ambient aerosol morphology, or internal structure of the particle, which in turn can affect the way a particle interacts with an environment of condensable clusters and organic vapors. To improve our ability to accurately predict ambient aerosol morphology, we must improve our knowledge of aerosol interfaces and their interactions with the ambient environment. Unfortunately, many techniques employed to measure interfacial properties do so in bulk solutions or in the presence of a ternary (e.g. solid) phase. In this talk, a novel method using biphasic microscale flows will be introduced for generating, trapping, and perturbing complex interfaces at atmospherically relevant conditions. These microfluidic experiments utilize high-speed imaging to monitor interfacial phenomena at the microscale and are performed with phase contrast and fluorescence microscopy on a temperature-controlled inverted microscope stage. From these experiments, interfacial thermodynamic properties such as surface or interfacial tension, rheological properties such as interfacial moduli, and kinetic properties such as mass transfer coefficients can be measured or inferred.

Thermodynamics of charged Lovelock: AdS black holes

International Nuclear Information System (INIS)

Prasobh, C.B.; Suresh, Jishnu; Kuriakose, V.C.

2016-01-01

We investigate the thermodynamic behavior of maximally symmetric charged, asymptotically AdS black hole solutions of Lovelock gravity. We explore the thermodynamic stability of such solutions by the ordinary method of calculating the specific heat of the black holes and investigating its divergences which signal second-order phase transitions between black hole states. We then utilize the methods of thermodynamic geometry of black hole spacetimes in order to explain the origin of these points of divergence. We calculate the curvature scalar corresponding to a Legendre-invariant thermodynamic metric of these spacetimes and find that the divergences in the black hole specific heat correspond to singularities in the thermodynamic phase space. We also calculate the area spectrum for large black holes in the model by applying the Bohr-Sommerfeld quantization to the adiabatic invariant calculated for the spacetime. (orig.)

Thermodynamics of charged Lovelock: AdS black holes

Science.gov (United States)

Prasobh, C. B.; Suresh, Jishnu; Kuriakose, V. C.

2016-04-01

We investigate the thermodynamic behavior of maximally symmetric charged, asymptotically AdS black hole solutions of Lovelock gravity. We explore the thermodynamic stability of such solutions by the ordinary method of calculating the specific heat of the black holes and investigating its divergences which signal second-order phase transitions between black hole states. We then utilize the methods of thermodynamic geometry of black hole spacetimes in order to explain the origin of these points of divergence. We calculate the curvature scalar corresponding to a Legendre-invariant thermodynamic metric of these spacetimes and find that the divergences in the black hole specific heat correspond to singularities in the thermodynamic phase space. We also calculate the area spectrum for large black holes in the model by applying the Bohr-Sommerfeld quantization to the adiabatic invariant calculated for the spacetime.

Thermodynamic modeling of the Eu–Te and Te–Yb systems

Energy Technology Data Exchange (ETDEWEB)

Ghamri, H., E-mail: ghamri.houda@hotmail.fr; Djaballah, Y.; Belgacem-Bouzida, A.

2015-09-15

Highlights: • The Eu–Te and Te–Yb binary systems were not previously thermodynamically assessed. • The Eu–Te and Te–Yb systems were assessed by using the CALPHAD technique. • A coherent set of thermodynamic parameters was obtained for both systems. • An agreement between the calculated results and experimental data was obtained for both systems. - Abstract: In this work, thermodynamic assessments of the Eu–Te and Te–Yb binary systems were carried out by using the CALculation of PHase Diagrams (CALPHAD) method based on the available experimental data including thermodynamic properties and phase equilibria. Reasonable models were constructed for all the phases of the two systems. The liquid phases were described by the substitutional solution model with the Redlich–Kister polynomial. The three intermetallic compounds, Eu{sub 4}Te{sub 7}, Eu{sub 3}Te{sub 7} and TeYb in the two systems, were treated as stoichiometric phases, while the non-stoichiometric phase (EuTe), which has an homogeneity range, was treated by a two-sublattice model following the schema: (Eu,Te){sub 0.5}(Te){sub 0.5}. A consistent set of thermodynamic parameters leading to reasonable agreement between the calculated results and experimental data was obtained.

High temperature crystallographic and thermodynamic investigations on synthetic calzirtite (Ca2Zr5Ti2O16)

International Nuclear Information System (INIS)

Jafar, M.; Phapale, S.; Achary, S.N.; Mishra, R.; Tyagi, A.K.

2016-01-01

Immobilization of actinides in the high level waste (HLW) produced from nuclear reactors in durable host matrix is one of the important concerns in nuclear power technology. Rock analogue (SYNROC) ceramic composites of titanates and zirconates namely zirconolite, calzirtite etc. have been proposed as alternate host matrix for disposal of long lived fission products. These minerals have ability to incorporate or immobilize a wider variety of ions simultaneously without further segregation to any other phases and are stable in geothermal conditions. Knowledge of thermodynamic stability of these minerals is important for their deployment as host matrix for actinide waste disposal. In this work crystal structure and thermodynamic parameters of a mineral analogous titanate termed as calzirtite (Ca 2 Zr 5 Ti 2 O 16 ) has been determined

A consistent thermodynamic database for cement minerals

International Nuclear Information System (INIS)

Blanc, P.; Claret, F.; Burnol, A.; Marty, N.; Gaboreau, S.; Tournassat, C.; Gaucher, E.C.; Giffault, E.; Bourbon, X.

2010-01-01

Document available in extended abstract form only. In the context of waste confinement and, more specifically, waste from the nuclear industry, concrete is used both as a confinement and as a building material. The exposure to high temperatures makes its geochemical behaviour difficult to predict over large periods of time. The present work aims to elucidate the temperature dependency of the thermodynamic functions related to minerals from the concrete or associated with some of its degradation products. To address precisely these functions is a key issue in order to investigate correctly the cement/clay interaction, from a geochemical point of view. A large set of experimental data has been collected, for the chemical systems CaO-SiO 2 -H 2 O, SO 3 -Al 2 O 3 - CaO-CO 2 -Cl-H 2 O and SiO 2 -Al 2 O 3 -CaO-H 2 O, including iron and magnesium bearing phases. Data include calorimetric measurements when available and results from equilibration experiments. The stability of C-S-H phases was considered as a specific issue, those phases may appear both as amorphous or crystalline minerals. In addition, the composition of amorphous minerals is still under debate. The phase diagram of crystalline phases was refined, providing the thermodynamic function of most of the main minerals. Then, we were able to build up a polyhedral model from the refined properties. The composition and the equilibrium constants of amorphous C-S-H, at room temperature, were derived from a large a set of equilibration data. Finally, the thermodynamic functions were completed by using the polyhedral model, both for amorphous and crystalline phases, in some cases. A verification test, based on reaction enthalpies derived from experimental data, indicates that predicted values for amorphous C-S-H are in close agreement with experimental data. For phases other than C-S-H, we have proceeded for each mineral the following way: - the equilibrium constant at 25 deg. C is selected from a single experimental

Thermodynamic database for the Co-Pr system

Directory of Open Access Journals (Sweden)

S.H. Zhou

2016-03-01

Full Text Available In this article, we describe data on (1 compositions for both as-cast and heat treated specimens were summarized in Table 1; (2 the determined enthalpy of mixing of liquid phase is listed in Table 2; (3 thermodynamic database of the Co-Pr system in TDB format for the research articled entitle Chemical partitioning for the Co-Pr system: First-principles, experiments and energetic calculations to investigate the hard magnetic phase W. Keywords: Thermodynamic database of Co-Pr, Solution calorimeter measurement, Phase diagram Co-Pr

Universalities of thermodynamic signatures in topological phases

NARCIS (Netherlands)

Kempkes, S. N.; Quelle, A.; de Morais Smith, C.

2016-01-01

Topological insulators (superconductors) are materials that host symmetry-protected metallic edge states in an insulating (superconducting) bulk. Although they are well understood, a thermodynamic description of these materials remained elusive, firstly because the edges yield a non-extensive

Towards a common thermodynamic database for speciation models

International Nuclear Information System (INIS)

Lee, J. van der; Lomenech, C.

2004-01-01

Bio-geochemical speciation models and reactive transport models are reaching an operational stage, allowing simulation of complex dynamic experiments and description of field observations. For decades, the main focus has been on model performance but at present, the availability and reliability of thermodynamic data is the limiting factor of the models. Thermodynamic models applied to real and complex geochemical systems require much more extended thermodynamic databases with many minerals, colloidal phases, humic and fulvic acids, cementitious phases and (dissolved) organic complexing agents. Here we propose a methodological approach to achieve, ultimately, a common, operational database including the reactions and constants of these phases. Provided they are coherent with the general thermodynamic laws, sorption reactions are included as well. We therefore focus on sorption reactions and parameter values associated with specific sorption models. The case of sorption on goethite has been used to illustrate the way the methodology handles the problem of inconsistency and data quality. (orig.)

Application of Statistical Thermodynamics in Refrigeration

International Nuclear Information System (INIS)

Avsec, J.; Marcic, M.

1999-01-01

The paper presents the mathematical model for computing the thermodynamical properties in the liquid, gas and two-phase domain by means of statistical thermodynamics. The paper features all important components (translation, rotation, internal rotation, vibration, intermolecular potential energy and influence of electron and nuclei excitation). To calculate the thermodynamic properties of real gases, we have developed the cluster theory, which yields better results than the virial equation. In case of real liquids, the Johnson-Zollweg-Gubbins model based on the modified Benedict-Webb-Rubin (BWR) equation was applied. The Lennard-Jones intermolecular potential was used. The analytical results are compared with the thermodynamical data and models obtained from classical thermodynamics, and they show relatively good agreement. (author)

Thermodynamic assessments of the Ag-Er and Er-Y systems

International Nuclear Information System (INIS)

Wang, S.L.; Wang, C.P.; Liu, X.J.; Tang, A.T.; Pan, F.S.; Ishida, K.

2010-01-01

The phase diagrams and thermodynamic properties in the Ag-Er and Er-Y binary systems have been assessed by using the CALPHAD (Calculation of Phase Diagrams) method on the basis of the experimental data including the thermodynamic properties and phase equilibria. The Gibbs free energies of the liquid, bcc, fcc, and hcp phases were described by the subregular solution model with the Redlich-Kister equation, and those of intermetallic compounds (Ag 2 Er and AgEr phases) were treated as stoichiometric compounds, and Ag 51 Er 14 phase was modeled by the sublattice model in the Ag-Er binary system. The thermodynamic parameters of the Ag-Er and Er-Y binary systems were obtained, and an agreement between the calculated results and experimental data was obtained for each binary system.

Thermodynamics of rotating black branes in (n+1)-dimensional Einstein-Born-Infeld gravity

International Nuclear Information System (INIS)

Dehghani, M. H.; Sedehi, H. R. Rastegar

2006-01-01

We construct a new class of charged rotating solutions of (n+1)-dimensional Einstein-Born-Infeld gravity with cylindrical or toroidal horizons in the presence of cosmological constant and investigate their properties. These solutions are asymptotically (anti)-de Sitter and reduce to the solutions of Einstein-Maxwell gravity as the Born-Infeld parameters goes to infinity. We find that these solutions can represent black branes, with inner and outer event horizons, an extreme black brane or a naked singularity provided the parameters of the solutions are chosen suitably. We compute temperature, mass, angular momentum, entropy, charge and electric potential of the black brane solutions. We obtain a Smarr-type formula and show that these quantities satisfy the first law of thermodynamics. We also perform a stability analysis by computing the heat capacity and the determinant of Hessian matrix of mass of the system with infinite boundary with respect to its thermodynamic variables in both the canonical and the grand-canonical ensembles, and show that the system is thermally stable in the whole phase space. Also, we find that there exists an unstable phase when the finite size effect is taken into account

Two-phase flows and heat transfer within systems with ambient pressure above the thermodynamic critical pressure

Science.gov (United States)

Hendricks, R. C.; Braun, M. J.; Mullen, R. L.

1986-01-01

In systems where the design inlet and outlet pressure P sub amb are maintained above the thermodynamic critical pressure P sub c, it is often assumed that heat and mass transfer are governed by single-phase relations and that two-phase flows cannot occur. This simple rule of thumb is adequate in many low-power designs but is inadequate for high-performance turbomachines, boilers, and other systems where two-phase regions can exist even though P sub amb P sub c. Heat and mass transfer and rotordynamic-fluid-mechanic restoring forces depend on momentum differences, and those for a two-phase zone can differ significantly from those for a single-phase zone. By using a laminar, variable-property bearing code and a rotating boiler code, pressure and temperature surfaces were determined that illustrate nesting of a two-phase region within a supercritical pressure region. The method of corresponding states is applied to bearings with reasonable rapport.

Thermodynamically consistent modeling and simulation of multi-component two-phase flow model with partial miscibility

KAUST Repository

Kou, Jisheng

2016-11-25

A general diffuse interface model with a realistic equation of state (e.g. Peng-Robinson equation of state) is proposed to describe the multi-component two-phase fluid flow based on the principles of the NVT-based framework which is a latest alternative over the NPT-based framework to model the realistic fluids. The proposed model uses the Helmholtz free energy rather than Gibbs free energy in the NPT-based framework. Different from the classical routines, we combine the first law of thermodynamics and related thermodynamical relations to derive the entropy balance equation, and then we derive a transport equation of the Helmholtz free energy density. Furthermore, by using the second law of thermodynamics, we derive a set of unified equations for both interfaces and bulk phases that can describe the partial miscibility of two fluids. A relation between the pressure gradient and chemical potential gradients is established, and this relation leads to a new formulation of the momentum balance equation, which demonstrates that chemical potential gradients become the primary driving force of fluid motion. Moreover, we prove that the proposed model satisfies the total (free) energy dissipation with time. For numerical simulation of the proposed model, the key difficulties result from the strong nonlinearity of Helmholtz free energy density and tight coupling relations between molar densities and velocity. To resolve these problems, we propose a novel convex-concave splitting of Helmholtz free energy density and deal well with the coupling relations between molar densities and velocity through very careful physical observations with a mathematical rigor. We prove that the proposed numerical scheme can preserve the discrete (free) energy dissipation. Numerical tests are carried out to verify the effectiveness of the proposed method.

Thermodynamics of charged black holes with a nonlinear electrodynamics source

International Nuclear Information System (INIS)

Gonzalez, Hernan A.; Hassaiene, Mokhtar; Martinez, Cristian

2009-01-01

We study the thermodynamical properties of electrically charged black hole solutions of a nonlinear electrodynamics theory defined by a power p of the Maxwell invariant, which is coupled to Einstein gravity in four and higher spacetime dimensions. Depending on the range of the parameter p, these solutions present different asymptotic behaviors. We compute the Euclidean action with the appropriate boundary term in the grand canonical ensemble. The thermodynamical quantities are identified and, in particular, the mass and the charge are shown to be finite for all classes of solutions. Interestingly, a generalized Smarr formula is derived and it is shown that this latter encodes perfectly the different asymptotic behaviors of the black hole solutions. The local stability is analyzed by computing the heat capacity and the electrical permittivity and we find that a set of small black holes is locally stable. In contrast to the standard Reissner-Nordstroem solution, there is a first-order phase transition between a class of these nonlinear charged black holes and the Minkowski spacetime.

Geometric description of BTZ black hole thermodynamics

International Nuclear Information System (INIS)

Quevedo, Hernando; Sanchez, Alberto

2009-01-01

We study the properties of the space of thermodynamic equilibrium states of the Banados-Teitelboim-Zanelli (BTZ) black hole in (2+1) gravity. We use the formalism of geometrothermodynamics to introduce in the space of equilibrium states a two-dimensional thermodynamic metric whose curvature is nonvanishing, indicating the presence of thermodynamic interaction, and free of singularities, indicating the absence of phase transitions. Similar results are obtained for generalizations of the BTZ black hole which include a Chern-Simons term and a dilatonic field. Small logarithmic corrections of the entropy turn out to be represented by small corrections of the thermodynamic curvature, reinforcing the idea that thermodynamic curvature is a measure of thermodynamic interaction.

Structural, electronic, elastic, and thermodynamic properties of CaSi, Ca2Si, and CaSi2 phases from first-principles calculations

Science.gov (United States)

Li, X. D.; Li, K.; Wei, C. H.; Han, W. D.; Zhou, N. G.

2018-06-01

The structural, electronic, elastic, and thermodynamic properties of CaSi, Ca2Si, and CaSi2 are systematically investigated by using first-principles calculations method based on density functional theory (DFT). The calculated formation enthalpies and cohesive energies show that CaSi2 possesses the greatest structural stability and CaSi has the strongest alloying ability. The structural stability of the three phases is compared according to electronic structures. Further analysis on electronic structures indicates that the bonding of these phases exhibits the combinations of metallic, covalent, and ionic bonds. The elastic constants are calculated, and the bulk modulus, shear modulus, Young's modulus, Poisson's ratio, and anisotropy factor of polycrystalline materials are deduced. Additionally, the thermodynamic properties were theoretically predicted and discussed.

Some problems on the thermodynamic state of the metallogenetic systems

International Nuclear Information System (INIS)

Mingarro, E.

1965-01-01

In order to get a classification of the uranium deposits, the geological processes have been ordered in thermodynamic systems according to the independent parameters that define their equilibrium state. Also, to apply the phase rule, we suppose that the ore forming elements are always ideally mobile components; that is, in the geological systems, these components are defined by their chemical potentials. In this paper, we show that in random conditions, i. e.; for any possible value of the factors of equilibrium or state the stable mineralizations are formed only in metasomatic regimes; so that the mineralogical sequence is a function both of the Helmholtz's free energy and the crystallisation pressure of the minerals. (Author) 7 refs

Modern thermodynamics

CERN Document Server

Ben-Naim, Arieh

2017-01-01

This textbook introduces thermodynamics with a modern approach, starting from four fundamental physical facts (the atomic nature of matter, the indistinguishability of atoms and molecules of the same species, the uncertainty principle, and the existence of equilibrium states) and analyzing the behavior of complex systems with the tools of information theory, in particular with Shannon's measure of information (or SMI), which can be defined on any probability distribution. SMI is defined and its properties and time evolution are illustrated, and it is shown that the entropy is a particular type of SMI, i.e. the SMI related to the phase-space distribution for a macroscopic system at equilibrium. The connection to SMI allows the reader to understand what entropy is and why isolated systems follow the Second Law of Thermodynamics. The Second Llaw is also formulated for other systems, not thermally isolated and even open with respect to the transfer of particles. All the fundamental aspects of thermodynamics are d...

Determination of structural, thermodynamic and phase properties in the Na2S-H2O system for application in a chemical heat pump

International Nuclear Information System (INIS)

Boer, R. de; Haije, W.G.; Veldhuis, J.B.J.

2002-01-01

Structural, thermodynamic and phase properties in the Na 2 S-H 2 O system for application in a chemical heat pump have been investigated using XRD, TG/DTA and melting point and vapour pressure determinations. Apart from the known crystalline phases Na 2 S·9H 2 O, Na 2 S·5H 2 O and Na 2 S a new phase Na 2 S·2H 2 O has been proven to exist. Na 2 S·((1)/(2))H 2 O is not a phase but a 3:1 mixture of Na 2 S and Na 2 S·2H 2 O, presumably stabilised by very slow dehydration kinetics. The vapour pressure-temperature equilibria of the sodium sulphide hydrates have been determined and a consistent set of thermodynamic functions for these compounds has been derived. XRD measurements indicate the topotactic character of the transitions between the hydration states

Thermodynamic modeling of the U–Zr system – A revisit

International Nuclear Information System (INIS)

Xiong, Wei; Xie, Wei; Shen, Chao; Morgan, Dane

2013-01-01

Graphical abstract: Display Omitted -- Abstract: A new thermodynamic description of the U–Zr system is developed using the CALPHAD (CALculation of PHAse Diagrams) method with the aid of ab initio calculations. Thermodynamic properties, such as heat capacity, activities, and enthalpy of mixing, are well predicted using the improved thermodynamic description in this work. The model-predicted enthalpies of formation for the bcc and δ phases are in good agreement with the results from DFT + U ab initio calculations. The calculations in this work show better agreements with experimental data comparing with the previous assessments. Using the integrated method of ab initio and CALPHAD modeling, an unexpected relation between the enthalpy of formation of the δ phase and energy of Zr with hexagonal structure is revealed and the model improved by fitting these energies together. The present work has demonstrated that ab initio calculations can help support a successful thermodynamic assessment of actinide systems, for which the thermodynamic properties are often difficult to measure

Simple solvable energy-landscape model that shows a thermodynamic phase transition and a glass transition.

Science.gov (United States)

Naumis, Gerardo G

2012-06-01

When a liquid melt is cooled, a glass or phase transition can be obtained depending on the cooling rate. Yet, this behavior has not been clearly captured in energy-landscape models. Here, a model is provided in which two key ingredients are considered in the landscape, metastable states and their multiplicity. Metastable states are considered as in two level system models. However, their multiplicity and topology allows a phase transition in the thermodynamic limit for slow cooling, while a transition to the glass is obtained for fast cooling. By solving the corresponding master equation, the minimal speed of cooling required to produce the glass is obtained as a function of the distribution of metastable states.

Thermodynamic assessments of the Ag-Gd and Ag-Nd systems

International Nuclear Information System (INIS)

Wang, S.L.; Wang, C.P.; Liu, X.J.; Ishida, K.

2009-01-01

The phase diagrams and thermodynamic properties in the Ag-Re (Re: Gd, Nd) binary systems have been assessed by using the CALPHAD (Calculation of Phase Diagrams) method on the basis of the experimental data including the thermodynamic properties and phase equilibria. The Gibbs free energies of the liquid, bcc, fcc, dhcp and hcp phases were described by the subregular solution model with the Redlich-Kister equation, and those of the intermetallic compounds (Ag 51 Gd 14 , Ag 2 Gd, AgGd, Ag 51 Nd 14 , αAg 2 Nd, βAg 2 Nd and AgNd phases) in these two binary systems were described by the sublattice model. The thermodynamic parameters of each phase in the Ag-Re (Re: Gd, Nd) binary systems were obtained, and an agreement between the calculated results and experimental data was obtained in each binary system.

Size effect on the dielectric properties of BaTiO3 nanoceramics in a modified Ginsburg-Landau-Devonshire thermodynamic theory

Science.gov (United States)

Lin, Shan; Lü, Tianquan; Jin, Changqing; Wang, Xiaohui

2006-10-01

Grain size effects on the dielectric properties of BaTiO3 nanoceramics have been studied by using the modified Ginsburg-Landau-Devonshire (GLD) thermodynamic theory. Considering the existence of internal stresses, it is found that with decreasing grain size the transition temperature of cubic-tetragonal phase decreases, while those of tetragonal-orthorhombic and orthorhombic-rhombohedral phases increase. With further reducing grain size, our model predicts that the two ferroelectric structures of orthorhombic and tetragonal phases will become unstable and disappear at a critical size, leaving only one stable ferroelectric phase of rhombohedral structure. Consequently, a theoretical phase diagram of the transition temperature versus grain size is established wherein two triple points and a reentrance behavior are indicated. The results are compared with experimental data.

Chemical engineering and thermodynamics using Mat lab

International Nuclear Information System (INIS)

Kim Heon; Kim, Moon Gap; Lee, Hak Yeong; Yeo, Yeong Gu; Ham, Seong Won

2002-02-01

This book consists of twelve chapters and four appendixes about chemical engineering and thermodynamics using Mat lab, which deals with introduction, energy budget, entropy, thermodynamics process, generalization on any fluid, engineering equation of state for PVT properties, deviation of the function, phase equilibrium of pure fluid, basic of multicomponent, phase equilibrium of compound by state equation, activity model and reaction system. The appendixes is about summary of computer program, related mathematical formula and material property of pure component.

Phase formation in as-solidified and heat-treated Al–Si–Cu–Mg–Ni alloys: Thermodynamic assessment and experimental investigation for alloy design

International Nuclear Information System (INIS)

Farkoosh, A.R.; Javidani, M.; Hoseini, M.; Larouche, D.; Pekguleryuz, M.

2013-01-01

Highlights: ► Phase formation in Al–Si–Ni–Cu–Mg–Fe system have been investigated. ► T-Al 9 FeNi, γ-Al 7 Cu 4 Ni, δ-Al 3 CuNi and ε-Al 3 Ni are formed at different Ni levels. ► Thermally stable Ni-bearing precipitates improved the overaged hardness. ► It was found that Ni:Cu and Ni:Fe ratios control the precipitation. ► δ-Al 3 CuNi phase has more contribution to strength compare to other precipitates. - Abstract: Thermodynamic simulations based on the CALPHAD method have been carried out to assess the phase formation in Al–7Si–(0–1)Ni–0.5Cu–0.35Mg alloys (in wt.%) under equilibrium and non-equilibrium (Scheil cooling) conditions. Calculations showed that the T-Al 9 FeNi, γ-Al 7 Cu 4 Ni, δ-Al 3 CuNi and ε-Al 3 Ni phases are formed at different Ni levels. By analyzing the calculated isothermal sections of the phase diagrams it was revealed that the Ni:Cu and Ni:Fe ratios control precipitation in this alloy system. In order to verify the simulation results, microstructural investigations in as-cast, solution treated and aged conditions were carried out using electron probe microanalysis (EPMA), scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Furthermore, cooling curve analysis (CCA) was also performed to determine the freezing range of the new alloys and porosity formation during solidification. Hardness measurements of the overaged samples showed that in this alloy system the δ-Al 3 CuNi phase has a greater influence on the overall strength of the alloys compared to the other Ni-bearing precipitates.

Phase formation in as-solidified and heat-treated Al-Si-Cu-Mg-Ni alloys: Thermodynamic assessment and experimental investigation for alloy design

Energy Technology Data Exchange (ETDEWEB)

Farkoosh, A.R., E-mail: amir.rezaeifarkoosh@mail.mcgill.ca [Department of Mining and Materials Engineering, McGill University, 3610 University, Aluminum Research Center - REGAL, Montreal, Quebec, Canada H3A 2B2 (Canada); Javidani, M. [Laval University, Department of Mining, Metallurgy and Materials Engineering, Aluminum Research Center - REGAL, 1065 Ave de la Medecine, Quebec, Canada G1V 0A6 (Canada); Hoseini, M. [Department of Mining and Materials Engineering, McGill University, 3610 University, Aluminum Research Center - REGAL, Montreal, Quebec, Canada H3A 2B2 (Canada); Larouche, D. [Laval University, Department of Mining, Metallurgy and Materials Engineering, Aluminum Research Center - REGAL, 1065 Ave de la Medecine, Quebec, Canada G1V 0A6 (Canada); Pekguleryuz, M. [Department of Mining and Materials Engineering, McGill University, 3610 University, Aluminum Research Center - REGAL, Montreal, Quebec, Canada H3A 2B2 (Canada)

2013-02-25

Highlights: Black-Right-Pointing-Pointer Phase formation in Al-Si-Ni-Cu-Mg-Fe system have been investigated. Black-Right-Pointing-Pointer T-Al{sub 9}FeNi, {gamma}-Al{sub 7}Cu{sub 4}Ni, {delta}-Al{sub 3}CuNi and {epsilon}-Al{sub 3}Ni are formed at different Ni levels. Black-Right-Pointing-Pointer Thermally stable Ni-bearing precipitates improved the overaged hardness. Black-Right-Pointing-Pointer It was found that Ni:Cu and Ni:Fe ratios control the precipitation. Black-Right-Pointing-Pointer {delta}-Al{sub 3}CuNi phase has more contribution to strength compare to other precipitates. - Abstract: Thermodynamic simulations based on the CALPHAD method have been carried out to assess the phase formation in Al-7Si-(0-1)Ni-0.5Cu-0.35Mg alloys (in wt.%) under equilibrium and non-equilibrium (Scheil cooling) conditions. Calculations showed that the T-Al{sub 9}FeNi, {gamma}-Al{sub 7}Cu{sub 4}Ni, {delta}-Al{sub 3}CuNi and {epsilon}-Al{sub 3}Ni phases are formed at different Ni levels. By analyzing the calculated isothermal sections of the phase diagrams it was revealed that the Ni:Cu and Ni:Fe ratios control precipitation in this alloy system. In order to verify the simulation results, microstructural investigations in as-cast, solution treated and aged conditions were carried out using electron probe microanalysis (EPMA), scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Furthermore, cooling curve analysis (CCA) was also performed to determine the freezing range of the new alloys and porosity formation during solidification. Hardness measurements of the overaged samples showed that in this alloy system the {delta}-Al{sub 3}CuNi phase has a greater influence on the overall strength of the alloys compared to the other Ni-bearing precipitates.

Thermodynamic Study of Tl6SBr4 Compound and Some Regularities in Thermodynamic Properties of Thallium Chalcohalides

Directory of Open Access Journals (Sweden)

Dunya Mahammad Babanly

2017-01-01

Full Text Available The solid-phase diagram of the Tl-TlBr-S system was clarified and the fundamental thermodynamic properties of Tl6SBr4 compound were studied on the basis of electromotive force (EMF measurements of concentration cells relative to a thallium electrode. The EMF results were used to calculate the relative partial thermodynamic functions of thallium in alloys and the standard integral thermodynamic functions (-ΔfG0, -ΔfH0, and S0298 of Tl6SBr4 compound. All data regarding thermodynamic properties of thallium chalcogen-halides are generalized and comparatively analyzed. Consequently, certain regularities between thermodynamic functions of thallium chalcogen-halides and their binary constituents as well as degree of ionization (DI of chemical bonding were revealed.

A new approach toward geometrical concept of black hole thermodynamics

Energy Technology Data Exchange (ETDEWEB)

Hendi, Seyed Hossein [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), Maragha (Iran, Islamic Republic of); Panahiyan, Shahram; Panah, Behzad Eslam; Momennia, Mehrab [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of)

2015-10-15

Motivated by the energy representation of Riemannian metric, in this paper we study different approaches toward the geometrical concept of black hole thermodynamics. We investigate thermodynamical Ricci scalar of Weinhold, Ruppeiner and Quevedo metrics and show that their number and location of divergences do not coincide with phase transition points arisen from heat capacity. Next, we introduce a new metric to solve these problems. We show that the denominator of the Ricci scalar of the new metric contains terms which coincide with different types of phase transitions. We elaborate the effectiveness of the new metric and shortcomings of the previous metrics with some examples. Furthermore, we find a characteristic behavior of the new thermodynamical Ricci scalar which enables one to distinguish two types of phase transitions. In addition, we generalize the new metric for the cases of more than two extensive parameters and show that in these cases the divergencies of thermodynamical Ricci scalar coincide with phase transition points of the heat capacity. (orig.)

A new approach toward geometrical concept of black hole thermodynamics

International Nuclear Information System (INIS)

Hendi, Seyed Hossein; Panahiyan, Shahram; Panah, Behzad Eslam; Momennia, Mehrab

2015-01-01

Motivated by the energy representation of Riemannian metric, in this paper we study different approaches toward the geometrical concept of black hole thermodynamics. We investigate thermodynamical Ricci scalar of Weinhold, Ruppeiner and Quevedo metrics and show that their number and location of divergences do not coincide with phase transition points arisen from heat capacity. Next, we introduce a new metric to solve these problems. We show that the denominator of the Ricci scalar of the new metric contains terms which coincide with different types of phase transitions. We elaborate the effectiveness of the new metric and shortcomings of the previous metrics with some examples. Furthermore, we find a characteristic behavior of the new thermodynamical Ricci scalar which enables one to distinguish two types of phase transitions. In addition, we generalize the new metric for the cases of more than two extensive parameters and show that in these cases the divergencies of thermodynamical Ricci scalar coincide with phase transition points of the heat capacity. (orig.)

THERMODYNAMIC PARAMETERS OF LEAD SULFIDE CRYSTALS IN THE CUBIC PHASE

Directory of Open Access Journals (Sweden)

T. O. Parashchuk

2016-07-01

Full Text Available Geometric and thermodynamic parameters of cubic PbS crystals were obtained using the computer calculations of the thermodynamic parameters within density functional theory method DFT. Cluster models for the calculation based on the analysis of the crystal and electronic structure. Temperature dependence of energy ΔE and enthalpy ΔH, Gibbs free energy ΔG, heat capacity at constant pressure CP and constant volume CV, entropy ΔS were determined on the basis of ab initio calculations of the crystal structure of molecular clusters. Analytical expressions of temperature dependences of thermodynamic parameters which were approximated with quantum-chemical calculation points have been presented. Experimental results compared with theoretically calculated data.

Statistical thermodynamics of alloys

International Nuclear Information System (INIS)

Gokcen, N.A.

1986-01-01

This book presents information on the following topics: consequences of laws of thermodynamics; Helmholtz and Gibbs energies; analytical forms of excess partial molar properties; single-component and multicomponent equilibria; phase rules and diagrams; lever rule; fermions, bosons, and Boltzons; approximate equations; enthalpy and heat capacity; Pd-H system; hydrogen-metal systems; limitations of Wagner model; energy of electrons and hols; dopants in semiconductors; derived thermodynamic properties; simple equivalent circuit; calculation procedure; multicompoent diagrams re; Engel-Brewer theories; p-n junctions; and solar cells

A thermodynamic evaluation of the Ti-Mo-C system

International Nuclear Information System (INIS)

Shim, J.H.; Oh, C.S.; Lee, D.N.

1996-01-01

A thermodynamic assessment of the Ti-Mo-C system has been made, employing a two-sublattice regular solution model for the solid solution and carbide phases and an ordinary subregular solution model for the liquid phase. A set of thermodynamic parameters describing the Gibbs energy of each individual phase in the Ti-Mo-C as well as the Ti-Mo systems was evaluated from thermochemical and phase equilibria information available in the literature through a computer-aided optimization procedure called the CALPHAD method. The comparison between the calculated and experimental results was made and practically important phase diagrams are also presented

First principles, thermal stability and thermodynamic assessment of the binary Ni-W system

Energy Technology Data Exchange (ETDEWEB)

Isomaeki, Iikka; Haemaelaeinen, Marko; Gasik, Michael [Aalto Univ., Espoo (Finland). School of Chemical Engineering; Braga, Maria H. [Porto Univ. (Portugal). CEMUC, Physics Engineering Dept.

2017-12-15

The Ni-W binary system was assessed using critically evaluated experimental data with assistance from first principles analysis and the CALPHAD method. The solution phases (liquid, fcc-A1 and bcc-A2) were modeled using the substitutional regular solution model. The recently discovered Ni{sub 8}W metastable phase was evaluated as Fe{sub 16}C{sub 2}- like martensite with three sublattices, and shown to be possibly stable according to first principles calculations. Ni{sub 8}W was also modeled as an interstitial compound, but the model is not good because the solubility of tungsten in nickel is very low, especially at low temperatures. There is no experimental evidence for such low solubility. The other binary compounds Ni{sub 4}W and Ni{sub 3}W were assessed as stoichiometric ones. Compared independent experimental and first principles data agree well with the calculated phase diagram using updated thermodynamic parameters.

On the electronic, structural, and thermodynamic properties of Au supported on α-Fe{sub 2}O{sub 3} surfaces and their interaction with CO

Energy Technology Data Exchange (ETDEWEB)

Nguyen, Manh-Thuong, E-mail: manhth.nguyen@gmail.com; Gebauer, Ralph [The Abdus Salam International Centre for Theoretical Physics, Strada Costiera 11, 34151 Trieste (Italy); Farnesi Camellone, Matteo, E-mail: mfarnesi@sissa.it [CNR-IOM DEMOCRITOS, Istituto Officina dei Materiali, Consiglio Nazionale delle Ricerche and SISSA Scuola Internazionale di Studi Superiori Avanzati, Via Bonomea 265, I-34136 Trieste (Italy)

2015-07-21

Extensive first principles calculations are carried out to investigate Au monomers and dimers supported on α-Fe{sub 2}O{sub 3}(0001) surfaces in terms of structure optimizations, electronic structure analyses, and ab initio thermodynamics calculations of surface phase diagrams. All computations rely on density functional theory in the generalized gradient approximation (Perdew-Burke-Ernzerhof (PBE)) and account for on-site Coulomb interactions via inclusion of a Hubbard correction (PBE+U). The relative stability of Au monomers/dimers on the stoichiometric termination of α-Fe{sub 2}O{sub 3}(0001) decorated with various vacancies (multiple oxygen vacancies, iron vacancy, and mixed iron-oxygen vacancies) has been computed as a function of the oxygen chemical potential. The charge rearrangement induced by Au at the oxide contact is analyzed in detail and discussed. On one hand, ab initio thermodynamics predicts that under O-rich conditions, structures obtained by replacing a surface Fe atom with a Au atom are thermodynamically stable over a wide range of temperatures. On the other hand, the complex of a CO molecule on a Au atom substituting surface Fe atoms is thermodynamically stable only in a much more narrow range of values of the O chemical potential under O-rich conditions. In the case of a Au dimer, under O-rich conditions, supported Au atoms at an O-Fe di-vacancy are more stable. However, upon CO adsorption, the complex of a CO molecule and 2 Au atoms located at a single Fe vacancy is more favorable.

Thermodynamic and kinetic characterization of polycyclic aromatic hydrocarbons in reversed-phase liquid chromatography.

Science.gov (United States)

Howerton, Samuel B; McGuffin, Victoria L

2003-07-15

The retention of six polycyclic aromatic hydrocarbons (PAHs) was characterized by reversed-phase liquid chromatography. The PAHs were detected by laser-induced fluorescence at four points along an optically transparent capillary column. The profiles were characterized in space and time using an exponentially modified Gaussian equation. The resulting parameters were used to calculate the retention factors, as well as the concomitant changes in molar enthalpy and molar volume, for each PAH on monomeric (2.7 micromol/m2) and polymeric (5.4 micromol/m2) octadecylsilica. The changes in molar enthalpy become more exothermic as ring number increases and as annelation structure becomes less condensed. The changes in molar volume become more negative as ring number increases for the planar PAHs, but are positive for the nonplanar solutes. In addition, the rate constants, as well as the concomitant activation enthalpy and activation volume, are calculated for the first time. The kinetic data demonstrate that many of the PAHs exhibit very fast transitions between the mobile and stationary phases. The transition state is very high in energy, and the activation enthalpies and volumes become greater as ring number increases and as annelation structure becomes less condensed. The changes in thermodynamic and kinetic behavior are much more pronounced for the polymeric phase than for the monomeric phase.

High-temperature experimental and thermodynamic modelling research on the pyrometallurgical processing of copper

Science.gov (United States)

Hidayat, Taufiq; Shishin, Denis; Decterov, Sergei A.; Hayes, Peter C.; Jak, Evgueni

2017-01-01

Uncertainty in the metal price and competition between producers mean that the daily operation of a smelter needs to target high recovery of valuable elements at low operating cost. Options for the improvement of the plant operation can be examined and decision making can be informed based on accurate information from laboratory experimentation coupled with predictions using advanced thermodynamic models. Integrated high-temperature experimental and thermodynamic modelling research on phase equilibria and thermodynamics of copper-containing systems have been undertaken at the Pyrometallurgy Innovation Centre (PYROSEARCH). The experimental phase equilibria studies involve high-temperature equilibration, rapid quenching and direct measurement of phase compositions using electron probe X-ray microanalysis (EPMA). The thermodynamic modelling deals with the development of accurate thermodynamic database built through critical evaluation of experimental data, selection of solution models, and optimization of models parameters. The database covers the Al-Ca-Cu-Fe-Mg-O-S-Si chemical system. The gas, slag, matte, liquid and solid metal phases, spinel solid solution as well as numerous solid oxide and sulphide phases are included. The database works within the FactSage software environment. Examples of phase equilibria data and thermodynamic models of selected systems, as well as possible implementation of the research outcomes to selected copper making processes are presented.

Thermodynamic efficiency of solar concentrators.

Science.gov (United States)

Shatz, Narkis; Bortz, John; Winston, Roland

2010-04-26

The optical thermodynamic efficiency is a comprehensive metric that takes into account all loss mechanisms associated with transferring flux from the source to the target phase space, which may include losses due to inadequate design, non-ideal materials, fabrication errors, and less than maximal concentration. We discuss consequences of Fermat's principle of geometrical optics and review étendue dilution and optical loss mechanisms associated with nonimaging concentrators. We develop an expression for the optical thermodynamic efficiency which combines the first and second laws of thermodynamics. As such, this metric is a gold standard for evaluating the performance of nonimaging concentrators. We provide examples illustrating the use of this new metric for concentrating photovoltaic systems for solar power applications, and in particular show how skewness mismatch limits the attainable optical thermodynamic efficiency.

Thermodynamic evaluation of the solidification phase of molten core–concrete under estimated Fukushima Daiichi nuclear power plant accident conditions

Energy Technology Data Exchange (ETDEWEB)

Kitagaki, Toru, E-mail: kitagaki.toru@jaea.go.jp; Yano, Kimihiko; Ogino, Hideki; Washiya, Tadahiro

2017-04-01

The solidification phases of molten core–concrete under the estimated molten core–concrete interaction (MCCI) conditions in the Fukushima Daiichi Nuclear Power Plant Unit 1 were predicted using the thermodynamic equilibrium calculation tool, FactSage 6.2, and the NUCLEA database in order to contribute toward the 1F decommissioning work and to understand the accident progression via the analytical results for the 1F MCCI products. We showed that most of the U and Zr in the molten core–concrete forms (U,Zr)O{sub 2} and (Zr,U)SiO{sub 4}, and the formation of other phases with these elements is limited. However, the formation of (Zr,U)SiO{sub 4} requires a relatively long time because it involves a change in the crystal structure from fcc-(U,Zr)O{sub 2} to tet-(U,Zr)O{sub 2}, followed by the formation of (Zr,U)SiO{sub 4} by reaction with SiO{sub 2}. Therefore, the formation of (Zr,U)SiO{sub 4} is limited under quenching conditions. Other common phases are the oxide phases, CaAl{sub 2}Si{sub 2}O{sub 8}, SiO{sub 2}, and CaSiO{sub 3}, and the metallic phases of the Fe–Si and Fe–Ni alloys. The solidification phenomenon of the crust under quenching conditions and that of the molten pool under thermodynamic equilibrium conditions in the 1F MCCI progression are discussed.

An Examination of the Phase Transition Thermodynamics of (S)- and (RS)-Naproxen as a Basis for the Design of Enantioselective Crystallization Processes.

Science.gov (United States)

Buchholz, Hannes; Emel'yanenko, Vladimir N; Lorenz, Heike; Verevkin, Sergey P

2016-05-01

A detailed experimental analysis of the phase transition thermodynamics of (S)-naproxen and (RS)-naproxen is reported. Vapor pressures were determined experimentally via the transpiration method. Sublimation enthalpies were obtained from the vapor pressures and from independent TGA measurements. Thermodynamics of fusion which have been well-studied in the literature were systematically remeasured by DSC. Both sublimation and fusion enthalpies were adjusted to one reference temperature, T = 298 K, using measured heat capacities of the solid and the melt phase by DSC. Average values from the measurements and from literature data were suggested for the sublimation and fusion enthalpies. In order to prove consistency of the proposed values the vaporization enthalpies obtained by combination of both were compared to vaporization enthalpies obtained by the group-additivity method and the correlation-gas chromatography method. The importance of reliable and precise phase transition data for thermochemical calculations such as the prediction of solid/liquid phase behaviour of chiral compounds is highlighted. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Application of thermodynamics to silicate crystalline solutions

Science.gov (United States)

Saxena, S. K.

1972-01-01

A review of thermodynamic relations is presented, describing Guggenheim's regular solution models, the simple mixture, the zeroth approximation, and the quasi-chemical model. The possibilities of retrieving useful thermodynamic quantities from phase equilibrium studies are discussed. Such quantities include the activity-composition relations and the free energy of mixing in crystalline solutions. Theory and results of the study of partitioning of elements in coexisting minerals are briefly reviewed. A thermodynamic study of the intercrystalline and intracrystalline ion exchange relations gives useful information on the thermodynamic behavior of the crystalline solutions involved. Such information is necessary for the solution of most petrogenic problems and for geothermometry. Thermodynamic quantities for tungstates (CaWO4-SrWO4) are calculated.

An introduction to thermodynamics and statistical mechanics

CERN Document Server

Saxena, A K

2016-01-01

An Introduction to Thermodynamics and Statistical Mechanics aims to serve as a text book for undergraduate hons.and postgraduate students of physics. The book covers First Law of Thermodynamics, Entropy and Second Law ofThermodynamics, Thermodynamic Relations, The Statistical Basis of Thermodynamics, Microcanonical Ensemble,Classical Statistical and Canonical Distribution, Grand Canonical Ensemble, Quantum Statistical Mechanics, PhaseTransitions, Fluctuations, Irreversible Processes and Transport Phenomena (Diffusion).SALIENT FEATURES:iC* Offers students a conceptual development of the subjectiC* Review questions at the end of chapters.NEW TO THE SECOND EDITIONiC* PVT SurfacesiC* Real Heat EnginesiC* Van der Waals Models (Qualitative Considerations)iC* Cluster ExpansioniC* Brownian Motion (Einstein's Theory)

Universality of P−V criticality in horizon thermodynamics

Energy Technology Data Exchange (ETDEWEB)

Hansen, Devin; Kubizňák, David [Perimeter Institute,31 Caroline St. N., Waterloo, Ontario, N2L 2Y5 (Canada); Department of Physics and Astronomy, University of Waterloo,Waterloo, Ontario, N2L 3G1 (Canada); Mann, Robert B. [Department of Physics and Astronomy, University of Waterloo,Waterloo, Ontario, N2L 3G1 (Canada)

2017-01-11

We study P−V criticality of black holes in Lovelock gravities in the context of horizon thermodynamics. The corresponding first law of horizon thermodynamics emerges as one of the Einstein-Lovelock equations and assumes the universal (independent of matter content) form δE=TδS−PδV, where P is identified with the total pressure of all matter in the spacetime (including a cosmological constant Λ if present). We compare this approach to recent advances in extended phase space thermodynamics of asymptotically AdS black holes where the ‘standard’ first law of black hole thermodynamics is extended to include a pressure-volume term, where the pressure is entirely due to the (variable) cosmological constant. We show that both approaches are quite different in interpretation. Provided there is sufficient non-linearity in the gravitational sector, we find that horizon thermodynamics admits the same interesting black hole phase behaviour seen in the extended case, such as a Hawking-Page transition, Van der Waals like behaviour, and the presence of a triple point. We also formulate the Smarr formula in horizon thermodynamics and discuss the interpretation of the quantity E appearing in the horizon first law.

Universality of P−V criticality in horizon thermodynamics

International Nuclear Information System (INIS)

Hansen, Devin; Kubizňák, David; Mann, Robert B.

2017-01-01

We study P−V criticality of black holes in Lovelock gravities in the context of horizon thermodynamics. The corresponding first law of horizon thermodynamics emerges as one of the Einstein-Lovelock equations and assumes the universal (independent of matter content) form δE=TδS−PδV, where P is identified with the total pressure of all matter in the spacetime (including a cosmological constant Λ if present). We compare this approach to recent advances in extended phase space thermodynamics of asymptotically AdS black holes where the ‘standard’ first law of black hole thermodynamics is extended to include a pressure-volume term, where the pressure is entirely due to the (variable) cosmological constant. We show that both approaches are quite different in interpretation. Provided there is sufficient non-linearity in the gravitational sector, we find that horizon thermodynamics admits the same interesting black hole phase behaviour seen in the extended case, such as a Hawking-Page transition, Van der Waals like behaviour, and the presence of a triple point. We also formulate the Smarr formula in horizon thermodynamics and discuss the interpretation of the quantity E appearing in the horizon first law.

Thermodynamics of gas adsorption on solid adsorbents

International Nuclear Information System (INIS)

Budrugeac, P.

1979-01-01

Starting with several hypotheses about the adsorbtion system and the adsorption phenomenon, a thermodynamic treatment of gas adsorption on solid adsorbants is presented. The relationships for determination from isotherms and calorimetric data of thermodynamic functions are derived. The problem of the phase changes in adsorbed layer is discussed. (author)

THERMODYNAMIC STUDY OF CHROMITE CAUSTICFUSION PROCESS

Institute of Scientific and Technical Information of China (English)

S.L. Zheng; Y. Zhang

2001-01-01

A new method for chromate cleaning production named chromite caustic fusion pro-cess, is advanced by Institute of Chemical Metallurgy, the Chinese Academy of Sci-ences. With sodium hydroxide as reaction medium, the new process is composed ofthree procedures: liquid phase oxidation of chromite - metastable phase separation -carbonation ammonium transition. Generally illustrating the new process and its fea-tures, this paper mainly studies the thermodynamics of chromite oxidation. The newprocess has much better practical results than the conventional chromate productionprocess in which sodium carbonate is used as reaction medium. The superiority is alsoshown through thermodynamic studies.``

Quantum phase transition and thermodynamic properties of a fourfold magnetic periodic system

Energy Technology Data Exchange (ETDEWEB)

Wang, Shuling, E-mail: wangshuling0324.student@sina.com [School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China); Li, Ruixue [School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China); Ding, Linjie [Department of Physics, China Three Gorges University, Yi Chang 443002 (China); Fu, Hua-Hua; Zhu, Si-cong [School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China); Ni, Yun [Huazhong University of Science and Technology, Wenhua College, Wuhan 430074 (China); Meng, Yan [Department of Physics, Xingtai University, Xingtai 054001 (China); Yao, Kailun [School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China); International Center of Materials Physics, Chinese Academy of Science, Shenyang 110015 (China)

2014-12-15

Based on the experimental synthesis of organic compound verdazyl radical β-3-(2,6-dichlorophenyl)-1,5-diphenylverdazyl, consisting of four antiferromagnetic couplings, we study the magnetic properties and thermodynamic behaviors for different antiferromagnetic interactions using Green’s function theory. Under different fields, there are five regimes containing two gapless phases and three magnetization plateaus (M=0, 1/2 and saturated magnetization) distinguished by four critical lines, which are evidenced by the two-site entanglement entropy and closely related to the energy spectra. In addition, we calculate the susceptibility and specific heat, to demonstrate the low-lying excitations at low temperatures. It will provide guidance for us to synthesize varieties of unconventional magnetic materials, and stimulate future studies on quantum spin systems. - Highlights: • The antiferromagnetic interaction-magnetic field phase diagrams are constructed. • The magnetization per site makes different contribution to the 1/2 plateau. • The spectral functions for different magnetic interactions are studied. • We investigate the gapless or gapped low-lying excitations at low temperatures.

Black hole thermodynamics with conical defects

Energy Technology Data Exchange (ETDEWEB)

Appels, Michael [Centre for Particle Theory, Durham University,South Road, Durham, DH1 3LE (United Kingdom); Gregory, Ruth [Centre for Particle Theory, Durham University,South Road, Durham, DH1 3LE (United Kingdom); Perimeter Institute,31 Caroline Street North, Waterloo, ON, N2L 2Y5 (Canada); Kubiznák, David [Perimeter Institute,31 Caroline Street North, Waterloo, ON, N2L 2Y5 (Canada)

2017-05-22

Recently we have shown https://www.doi.org/10.1103/PhysRevLett.117.131303 how to formulate a thermodynamic first law for a single (charged) accelerated black hole in AdS space by fixing the conical deficit angles present in the spacetime. Here we show how to generalise this result, formulating thermodynamics for black holes with varying conical deficits. We derive a new potential for the varying tension defects: the thermodynamic length, both for accelerating and static black holes. We discuss possible physical processes in which the tension of a string ending on a black hole might vary, and also map out the thermodynamic phase space of accelerating black holes and explore their critical phenomena.

Thermodynamic instability of charged dilaton black holes in AdS spaces

International Nuclear Information System (INIS)

Sheykhi, A.; Dehghani, M. H.; Hendi, S. H.

2010-01-01

We study thermodynamic instability of a class of (n+1)-dimensional charged dilatonic spherically symmetric black holes in the background of the anti-de Sitter universe. We calculate the quasilocal mass of the anti-de Sitter dilaton black hole through the use of the subtraction method of Brown and York. We find a Smarr-type formula and perform a stability analysis in the canonical ensemble and disclose the effect of the dilaton field on the thermal stability of the solutions. Our study shows that the solutions are thermally stable for small α, while for large α the system has an unstable phase, where α is a coupling constant between the dilaton and matter field.

A sub-grid, mixture-fraction-based thermodynamic equilibrium model for gas phase combustion in FIRETEC: development and results

Science.gov (United States)

M. M. Clark; T. H. Fletcher; R. R. Linn

2010-01-01

The chemical processes of gas phase combustion in wildland fires are complex and occur at length-scales that are not resolved in computational fluid dynamics (CFD) models of landscape-scale wildland fire. A new approach for modelling fire chemistry in HIGRAD/FIRETEC (a landscape-scale CFD wildfire model) applies a mixture– fraction model relying on thermodynamic...

New perspectives in thermodynamics

International Nuclear Information System (INIS)

Serrin, J.

1986-01-01

The last decade has seen a unity of method and approach in the foundations of thermodynamics and continuum mechanics, in which rigorous laws of thermodynamics have been combined with invariance notions of mechanics to produce new and deep understanding. Real progress has been made in finding a set of appropriate concepts for classical thermodynamics, by which energy conservation and the Clausius inequality can be given well-defined meanings for arbitrary processes and which allow an approach to the entropy concept which is free of traditional ambiguities. There has been, moreover, a careful scrutiny of long established but nevertheless not sharply defined concepts such as the Maxwell equal-area rule, the famous Gibbs phase rule, and the equivalence of work and heat. The thirteen papers in this volume accordingly gather together for the first time the many ideas and concepts which have raised classical thermodynamics from a heuristic and intuitive science to the level of precision presently demanded of other branches of mathematical physics

First-principles calculations on thermodynamic properties of BaTiO3 rhombohedral phase.

Science.gov (United States)

Bandura, Andrei V; Evarestov, Robert A

2012-07-05

The calculations based on the linear combination of atomic orbitals have been performed for the low-temperature phase of BaTiO(3) crystal. Structural and electronic properties, as well as phonon frequencies were obtained using hybrid PBE0 exchange-correlation functional. The calculated frequencies and total energies at different volumes have been used to determine the equation of state and thermal contribution to the Helmholtz free energy within the quasiharmonic approximation. For the first time, the bulk modulus, volume thermal expansion coefficient, heat capacity, and Grüneisen parameters in BaTiO(3) rhombohedral phase have been estimated at zero pressure and temperatures form 0 to 200 K, based on the results of first-principles calculations. Empirical equation has been proposed to reproduce the temperature dependence of the calculated quantities. The agreement between the theoretical and experimental thermodynamic properties was found to be satisfactory. Copyright © 2012 Wiley Periodicals, Inc.

Design of Low-Melting Point Compositions Suitable for Transient Liquid Phase Sintering of PM Steels Based on a Thermodynamic and Kinetic Study

Science.gov (United States)

Bernardo, Elena; de Oro, Raquel; Campos, Mónica; Torralba, José Manuel

2014-04-01

The possibility of tailoring the characteristics of a liquid metal is an important asset in a wide number of processing techniques. For most of these processes, the nature and degree of the interaction between liquid and solid phases are usually a focus of interest since they determine liquid properties such as wettability and infiltration capacity. Particularly, within the powder metallurgy (PM) technology, it is considered one of the key aspects to obtain high performance steels through liquid phase sintering. In this work, it is proved how thermodynamic and kinetics software is a powerful tool to study the liquid/solid interactions. The assessment of different liquid phase promoters for transient liquid phase sintering is addressed through the use of ThermoCalc and DICTRA calculations. Besides melting temperatures, particular attention is given to the solubility phenomena between the phases and the kinetics of these processes. Experimental validation of thermodynamic results is carried out by wetting and infiltration experiments at high temperatures. Compositions presenting different liquid/solid solubility are evaluated and directly correlated to the behavior of the liquid during a real sintering process. Therefore, this work opens the possibility to optimize liquid phase compositions and predict the liquid behavior from the design step, which is considered of high technological value for the PM industry.

Highly efficient molecular simulation methods for evaluation of thermodynamic properties of crystalline phases

Science.gov (United States)

Moustafa, Sabry Gad Al-Hak Mohammad

Molecular simulation (MS) methods (e.g. Monte Carlo (MC) and molecular dynamics (MD)) provide a reliable tool (especially at extreme conditions) to measure solid properties. However, measuring them accurately and efficiently (smallest uncertainty for a given time) using MS can be a big challenge especially with ab initio-type models. In addition, comparing with experimental results through extrapolating properties from finite size to the thermodynamic limit can be a critical obstacle. We first estimate the free energy (FE) of crystalline system of simple discontinuous potential, hard-spheres (HS), at its melting condition. Several approaches are explored to determine the most efficient route. The comparison study shows a considerable improvement in efficiency over the standard MS methods that are known for solid phases. In addition, we were able to accurately extrapolate to the thermodynamic limit using relatively small system sizes. Although the method is applied to HS model, it is readily extended to more complex hard-body potentials, such as hard tetrahedra. The harmonic approximation of the potential energy surface is usually an accurate model (especially at low temperature and large density) to describe many realistic solid phases. In addition, since the analysis is done numerically the method is relatively cheap. Here, we apply lattice dynamics (LD) techniques to get the FE of clathrate hydrates structures. Rigid-bonds model is assumed to describe water molecules; this, however, requires additional orientation degree-of-freedom in order to specify each molecule. However, we were able to efficiently avoid using those degrees of freedom through a mathematical transformation that only uses the atomic coordinates of water molecules. In addition, the proton-disorder nature of hydrate water networks adds extra complexity to the problem, especially when extrapolating to the thermodynamic limit is needed. The finite-size effects of the proton disorder contribution is

External temperature and pressure effects on thermodynamic properties and mechanical stability of yttrium chalcogenides YX (X=S, Se and Te)

Energy Technology Data Exchange (ETDEWEB)

Seddik, T. [Laboratoire de Physique Quantique et de Modélisation Mathématique, Université de Mascara, 29000 Mascara (Algeria); Khenata, R., E-mail: khenata_rabah@yahoo.fr [Laboratoire de Physique Quantique et de Modélisation Mathématique, Université de Mascara, 29000 Mascara (Algeria); Bouhemadou, A.; Guechi, N. [Laboratory for Developing New Materials and their Characterization, Department of Physics, Faculty of Science, University of Setif, 19000 Setif (Algeria); Sayede, A. [Université Lille Nord de France, F-59000 Lille (France); Université-Artois, UCCS, F-62300 Lens (France); CNRS, UMR 8181, F-59650 Villeneuve d’Ascq (France); Varshney, D. [Materials Science Laboratory, School of Physics, Vigyan Bhavan, Devi Ahilya University, Khandwa Road Campus, Indore 452001, Madhya Pradesh (India); Al-Douri, Y. [Institute of Nono Electronic Engineering, University Malaysia Perlis, 01000 Kangar, Perlis (Malaysia); Reshak, A.H. [Institute of Complex Systems, FFPW, CENAKVA, University of South Bohemia in CB, Nove Hrady 37333 (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Bin-Omran, S. [Department of Physics and Astronomy, Faculty of Science, King Saud University, PO Box 2455, Riyadh 11451 (Saudi Arabia)

2013-11-01

The full potential linearized augmented plane wave method within the framework of density functional theory is employed to investigate the structural, thermodynamic and elastic properties of the yttrium chalcogenides (YX: X=S, Se, and Te) in their low-pressure phase (Fm3{sup ¯}m) and high-pressure phase (Pm3{sup ¯}m). The exchange-correlation potential is treated with the generalized gradient approximation of Perdew–Burke–Ernzerhof (GGA-PBE). Temperature dependence of the volume and both adiabatic and isothermal bulk moduli is predicted for a temperature range from 0to1200K for the both phases of the herein considered materials. Furthermore, we have analyzed the thermodynamic properties such as the heat capacities, C{sub V} and C{sub P}, thermal expansion, α, and Debye temperature, Θ{sub D,} under variable pressure and temperature. We have calculated the isothermal elastic constants C{sub ij}{sup T} of the YX monochalcogenides in both NaCl-B1 and CsCl-B2 phases at zero pressure and a temperature range 0−1200K. The results show that rare earth yttrium monochalcogenides are mechanically stable at high temperature. The elastic anisotropy of all studied materials in the two phases has been studied using three different methods.

Exploration of phase transition in Th2C under pressure: An Ab-initio investigation

Science.gov (United States)

Sahoo, B. D.; Joshi, K. D.; Kaushik, T. C.

2018-05-01

With the motivation of searching for new compounds in the Th-C system, we have performed ab initio evolutionary searches for all the stable compounds in this binary system in the pressure range of 0-100 GPa. We have found previously unknown, thermodynamically stable, composition Th2C along with experimentally known ThC, ThC2 and Th2C3 phases at 0 GPa. Interestingly at pressure of 13 GPa the predicted ground state orthorhombic (SG no. 59, Pmmn) phase of Th2C transforms to trigonal (SG no. 164, P-3m1) phase. We also find the mechanical and dynamical stability of both the phases. Further, the theoretically determined equation of state has been utilized to derive various physical quantities such as zero pressure equilibrium volume, bulk modulus, and pressure derivative of bulk modulus of Pmmn phase at ambient conditions.

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

Energy Technology Data Exchange (ETDEWEB)

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

2010-01-10

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

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

International Nuclear Information System (INIS)

Lazerges, Mathieu; Rietveld, Ivo B.; Corvis, Yohann; Ceolin, Rene; Espeau, Philippe

2010-01-01

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

Thermodynamic studies on charge-coupled substituted synthetic monazite

Energy Technology Data Exchange (ETDEWEB)

Rawat, D. [Product Development Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Phapale, S. [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Mishra, R., E-mail: mishrar@barc.gov.in [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Dash, S. [Product Development Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

2017-04-15

Phosphate-based monazite ceramic is considered worldwide as a potential crystalline host matrix for immobilization of long-lived tri- and tetra-valent actinides present in high-level nuclear waste. Monazite is chemically stable with respect to the leaching processes and has high radiation stability. The present paper describes the influence of charged coupled (Ca{sup 2+}, Th{sup 4+}) substitution in place of La{sup 3+} on thermodynamic stability of synthetic monazite ceramics. XRD-analysis of Ca, Th substituted LaPO{sub 4} viz., La{sub 1-x}Ca{sub x/2}Th{sub x/2}PO{sub 4} (0 ≤ x ≤ 1) points to the formation of ideal solid-solution in the entire range of composition. However, thermodynamic analysis indicates deviation from ideal solid-solution with a minima at x = 0.25. The substituted La{sub 1-x}Ca{sub x/2}Th{sub x/2}PO{sub 4} system is found to be iso-entropic and stabilized mainly by enthalpy. Enthalpies of formation as a function of Ca{sup 2+}, Th{sup 4+} substitution were analysed to provide insights into the development of thermodynamically stable nuclear waste matrix.

Study on thermal property of lauric–palmitic–stearic acid/vermiculite composite as form-stable phase change material for energy storage

Directory of Open Access Journals (Sweden)

Nan Zhang

2015-09-01

Full Text Available The form-stable composite phase change material of lauric–palmitic–stearic acid ternary eutectic mixture/vermiculite was prepared by vacuum impregnation method for thermal energy storage. The maximum mass fraction of lauric–palmitic–stearic acid ternary eutectic mixture retained in vermiculite was determined as 50 wt% without melted phase change material seepage from the composite phase change material. Fourier transformation infrared spectroscope and scanning electron microscope were used to characterize the structure and morphology of the prepared lauric–palmitic–stearic acid ternary eutectic mixture/vermiculite form-stable composite phase change material, and the results indicate that lauric–palmitic–stearic acid ternary eutectic mixture was well confined into the layer porous structure of vermiculite by physical reaction. The melting and freezing temperatures and latent heats were measured by differential scanning calorimeter as 31.4°C and 30.3°C, and 75.8 and 73.2 J/g, respectively. Thermal cycling test showed that there was no significant change in the thermal properties of lauric–palmitic–stearic acid ternary eutectic mixture/vermiculite form-stable composite phase change material after 1000 thermal cycles. Moreover, 2 wt% expanded graphite was added to improve the thermal conductivity of lauric–palmitic–stearic acid ternary eutectic mixture/vermiculite form-stable composite phase change material. All results indicated that the prepared lauric–palmitic–stearic acid ternary eutectic mixture/vermiculite form-stable composite phase change material had suitable thermal properties and good thermal reliability for the application of thermal energy storage in building energy efficiency.

Phase diagram of power law and Lennard-Jones systems: Crystal phases

International Nuclear Information System (INIS)

Travesset, Alex

2014-01-01

An extensive characterization of the low temperature phase diagram of particles interacting with power law or Lennard-Jones potentials is provided from Lattice Dynamical Theory. For power law systems, only two lattice structures are stable for certain values of the exponent (or softness) (A15, body centered cube (bcc)) and two more (face centered cubic (fcc), hexagonal close packed (hcp)) are always stable. Among them, only the fcc and bcc are equilibrium states. For Lennard-Jones systems, the equilibrium states are either hcp or fcc, with a coexistence curve in pressure and temperature that shows reentrant behavior. The hcp solid never coexists with the liquid. In all cases analyzed, for both power law and Lennard-Jones potentials, the fcc crystal has higher entropy than the hcp. The role of anharmonic terms is thoroughly analyzed and a general thermodynamic integration to account for them is proposed

On Teaching Thermodynamics

Science.gov (United States)

Debbasch, F.

2011-01-01

The logical structure of classical thermodynamics is presented in a modern, geometrical manner. The first and second law receive clear, operatively oriented statements and the Gibbs free energy extremum principle is fully discussed. Applications relevant to chemistry, such as phase transitions, dilute solutions theory and, in particular, the law…

The Pu–U–Am system: An ab initio informed CALPHAD thermodynamic study

International Nuclear Information System (INIS)

Perron, A.; Turchi, P.E.A.; Landa, A.; Söderlind, P.; Ravat, B.; Oudot, B.; Delaunay, F.

2015-01-01

Highlights: • The ab initio informed CALPHAD assessment of the Am–U system has been realized. • A strong tendency toward phase separation across the whole composition range is predicted. • The ab initio informed Pu–U–Am thermodynamic database has been developed. • The solubility of Am and U in the liquid phase is improved by adding Pu. • The δ-Pu (fcc) phase is strongly stabilized by Am, on the contrary to the bcc phase. - Abstract: Phase diagram and thermodynamic properties of the Am–U system, that are experimentally unknown, are calculated using the CALPHAD method with input from ab initio electronic-structure calculations for the fcc and bcc phases. A strong tendency toward phase separation across the whole composition range is predicted. In addition, ab initio informed Pu–U and Am–Pu thermodynamic assessments are combined to build a Pu–U–Am thermodynamic database. Regarding the Pu-rich corner of the ternary system, predictions indicate that Am acts as a powerful δ-Pu (fcc) stabilizer. In the U-rich corner, similar predictions are made but to a lesser extent. In both cases, the bcc phase is destabilized and the fcc phase is enhanced. Finally, results and methodology are discussed and compared with previous assessments and guidelines are provided for further experimental studies

The Pu–U–Am system: An ab initio informed CALPHAD thermodynamic study

Energy Technology Data Exchange (ETDEWEB)

Perron, A., E-mail: perron1@llnl.gov [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Turchi, P.E.A.; Landa, A.; Söderlind, P. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Ravat, B.; Oudot, B.; Delaunay, F. [CEA-Centre de Valduc, 21120 Is sur Tille (France)

2015-03-15

Highlights: • The ab initio informed CALPHAD assessment of the Am–U system has been realized. • A strong tendency toward phase separation across the whole composition range is predicted. • The ab initio informed Pu–U–Am thermodynamic database has been developed. • The solubility of Am and U in the liquid phase is improved by adding Pu. • The δ-Pu (fcc) phase is strongly stabilized by Am, on the contrary to the bcc phase. - Abstract: Phase diagram and thermodynamic properties of the Am–U system, that are experimentally unknown, are calculated using the CALPHAD method with input from ab initio electronic-structure calculations for the fcc and bcc phases. A strong tendency toward phase separation across the whole composition range is predicted. In addition, ab initio informed Pu–U and Am–Pu thermodynamic assessments are combined to build a Pu–U–Am thermodynamic database. Regarding the Pu-rich corner of the ternary system, predictions indicate that Am acts as a powerful δ-Pu (fcc) stabilizer. In the U-rich corner, similar predictions are made but to a lesser extent. In both cases, the bcc phase is destabilized and the fcc phase is enhanced. Finally, results and methodology are discussed and compared with previous assessments and guidelines are provided for further experimental studies.

Theoretical investigation of the structural stabilities, optoelectronic properties and thermodynamic characteristics of GaPxSb1-x ternary alloys

Science.gov (United States)

Oumelaz, F.; Nemiri, O.; Boumaza, A.; Ghemid, S.; Meradji, H.; Bin Omran, S.; El Haj Hassan, F.; Rai, D. P.; Khenata, R.

2018-06-01

In this theoretical study, we have investigated the structural, phase transition, electronic, thermodynamic and optical properties of GaPxSb1-x ternary alloys. Our calculations are performed with the WIEN2k code based on density functional theory using the full-potential linearized augmented plane wave method. For the electron exchange-correlation potential, a generalized gradient approximation within Wu-Cohen scheme is considered. The recently developed Tran-Blaha modified Becke-Johnson potential has also been used to improve the underestimated band gap. The structural properties, including the lattice constants, the bulk moduli and their pressure derivatives are in very good agreement with the available experimental data and theoretical results. Several structural phase transitions were studied here to establish the stable structure and to predict the phase transition under hydrostatic pressure. The computed transition pressure (Pt) of the material of our interest from the zinc blende (B3) to the rock salt (B1) phase has been determined and found to agree well with the experimental and theoretical data. The calculated band structure shows that GaSb binary compound and the ternary alloys are direct band gap semiconductors. Optical parameters such as the dielectric constants and the refractive indices are calculated and analyzed. The thermodynamic results are also interpreted and analyzed.

Application of calorimetry and thermodynamics to critical problems in materials science

International Nuclear Information System (INIS)

Atake, Tooru

2009-01-01

Calorimetry and thermodynamic studies have long been playing a very important role in the research fields of fundamental science and technology. Some topics and examples of thermodynamics studies are given, and the details are explained on the basis of the present author's experience, focusing attention to application of adiabatic calorimetry and thermodynamics to solve critical problems in materials science: (1) condensed gas calorimetry and third law entropy, (2) phase transition and polymorphism in simple molecular crystals, (3) incommensurate phase transitions, (4) particle size effects on the phase transitions in ferroelectric/ferroelastic crystals, (5) relaxor ferroelectrics and multi-ferroics, and some other topics in materials science and technology

Thermodynamics of charged rotating dilaton black branes with power-law Maxwell field

International Nuclear Information System (INIS)

Zangeneh, M.K.; Sheykhi, A.; Dehghani, M.H.

2015-01-01

In this paper, we construct a new class of charged rotating dilaton black brane solutions, with a complete set of rotation parameters, which is coupled to a nonlinear Maxwell field. The Lagrangian of the matter field has the form of the power-law Maxwell field. We study the causal structure of the spacetime and its physical properties in ample details. We also compute thermodynamic and conserved quantities of the spacetime, such as the temperature, entropy, mass, charge, and angular momentum. We find a Smarr-formula for the mass and verify the validity of the first law of thermodynamics on the black brane horizon. Finally, we investigate the thermal stability of solutions in both the canonical and the grand-canonical ensembles and disclose the effects of dilaton field and nonlinearity of the Maxwell field on the thermal stability of the solutions. We find that, for α ≤ 1, charged rotating black brane solutions are thermally stable independent of the values of the other parameters. For α > 1, the solutions can encounter an unstable phase depending on the metric parameters. (orig.)

Predictions of titanium alloy properties using thermodynamic modeling tools

Science.gov (United States)

Zhang, F.; Xie, F.-Y.; Chen, S.-L.; Chang, Y. A.; Furrer, D.; Venkatesh, V.

2005-12-01

Thermodynamic modeling tools have become essential in understanding the effect of alloy chemistry on the final microstructure of a material. Implementation of such tools to improve titanium processing via parameter optimization has resulted in significant cost savings through the elimination of shop/laboratory trials and tests. In this study, a thermodynamic modeling tool developed at CompuTherm, LLC, is being used to predict β transus, phase proportions, phase chemistries, partitioning coefficients, and phase boundaries of multicomponent titanium alloys. This modeling tool includes Pandat, software for multicomponent phase equilibrium calculations, and PanTitanium, a thermodynamic database for titanium alloys. Model predictions are compared with experimental results for one α-β alloy (Ti-64) and two near-β alloys (Ti-17 and Ti-10-2-3). The alloying elements, especially the interstitial elements O, N, H, and C, have been shown to have a significant effect on the β transus temperature, and are discussed in more detail herein.

Thermodynamic evaluation of the Ti-Al-O ternary system

International Nuclear Information System (INIS)

Lee, B.-J.

1997-01-01

A thermodynamic evaluation of the Ti-Al-O ternary system has been made by using thermodynamic models for the Gibbs energy of individual phases. A consistent model parameter set was determined so that the calculation of isothermal sections and other thermodynamic quantities becomes possible. The agreement between calculation and corresponding experimental data was generally good along large temperature and composition range. (orig.)

Thermodynamics, core-level spectroscopy, morphology, and work function study of different TiCl3 crystalline phases: A theoretical approach

International Nuclear Information System (INIS)

Guo, Lei; Li, Wenpo; Feng, Wenjiang; Zhang, Zhipeng; Zhang, Shengtao

2014-01-01

Highlights: • Three TiCl 3 polymorphs materials were systematically investigated. • Structural results agree well with experimental and available theoretical data. • Morphological and thermodynamic properties were computed and analyzed. • Core-level spectroscopy and work function were obtained. - Abstract: Computer simulation has been widely applied in many research fields owing to its superiority in revealing an insight understanding of the phenomena. In this work, the thermodynamics, core-level spectroscopy, morphology, and work function of TiCl 3 with three different crystalline phases (α, β, and γ) have been comprehensively computed employing the Materials Studio package. Our computational DFT-D approach gives a structural description of the TiCl 3 phases in good agreement with experiment. The core-level spectroscopy confirmed that α, β, and γ modifications for TiCl 3 have lightly affected on the valences of the constitutional elements. A series of possible growth faces (h k l) were deduced using the classic Bravais–Friedel–Donnay–Harker (BFDH) model. We conclude that the sequence of work function for (0 0 1) surface was α > β ≈ γ

Thermodynamic properties of charged three-dimensional black holes in the scalar-tensor gravity theory

Science.gov (United States)

Dehghani, M.

2018-02-01

Making use of the suitable transformation relations, the action of three-dimensional Einstein-Maxwell-dilaton gravity theory has been obtained from that of scalar-tensor modified gravity theory coupled to the Maxwell's electrodynamics as the matter field. Two new classes of the static three-dimensional charged dilatonic black holes, as the exact solutions to the coupled scalar, electromagnetic and gravitational field equations, have been obtained in the Einstein frame. Also, it has been found that the scalar potential can be written in the form of a generalized Liouville-type potential. The conserved black hole charge and masses as well as the black entropy, temperature, and electric potential have been calculated from the geometrical and thermodynamical approaches, separately. Through comparison of the results arisen from these two alternative approaches, the validity of the thermodynamical first law has been proved for both of the new black hole solutions in the Einstein frame. Making use of the canonical ensemble method, a black hole stability or phase transition analysis has been performed. Regarding the black hole heat capacity, with the black hole charge as a constant, the points of type-1 and type-2 phase transitions have been determined. Also, the ranges of the black hole horizon radius at which the Einstein black holes are thermally stable have been obtained for both of the new black hole solutions. Then making use of the inverse transformation relations, two new classes of the string black hole solutions have been obtained from their Einstein counterpart. The thermodynamics and thermal stability of the new string black hole solutions have been investigated. It has been found that thermodynamic properties of the new charged black holes are identical in the Einstein and Jordan frames.

Iron in carbonate containing AFm phases

International Nuclear Information System (INIS)

Dilnesa, B.Z.; Lothenbach, B.; Le Saout, G.; Renaudin, G.; Mesbah, A.; Filinchuk, Y.; Wichser, A.; Wieland, E.

2011-01-01

One of the AFm phases in hydrated Portland cement is Ca 3 (Al x Fe 2 - x )O 6 .CaCO 3 .nH 2 O. It is based on hexagonal and platey structural elements and the interlayer structure incorporates CO 3 2- . The solid phases were experimentally synthesized and characterized by different techniques including X-ray techniques (XRD and EXAFS) and vibrational spectroscopy techniques (IR, Raman). Fe-monocarbonate (Fe-Mc) and Al-monocarbonate (Al-Mc) were found to be stable up to 50 o C, while Fe-hemicarbonate (Fe-Hc) was unstable with respect to Fe-Mc in the presence of calcite. Fe-Mc has a rhombohedral R3-barc symmetry which is different from the triclinic of the Al analogue. Both XRD and thermodynamic modelling of the liquid compositions indicated that Al-Mc and the Fe-Mc phases do not form solid solution. The solubility products were calculated experimentally at 20 o C and 50 o C. Under standards condition the solubility products and other thermodynamic parameters were estimated using temperature-solubility product extrapolation and found to be logK S0 (Fe-Mc) = -34.59 ± 0.50, logK S0 (Fe-Hc) = -30.83 ± 0.50 and logK S0 (Al-Mc) = -31.32 ± 0.50.

Phase-field modeling of Mn-Ni-Si precipitate behavior on the bcc-Fe matrix

International Nuclear Information System (INIS)

Chang, Kun Ok; Kwon, Jun Hyun

2016-01-01

The formation of Mn-Ni-Si precipitate (hereafter MNS precipitate) is widely accepted by one of the main reasons of late stage hardening and embrittlement of Reactor Pressure Vessel (RPV) during nuclear power plant (NPP) operation. Since MNS precipitate is not considered in current regulatory model, this late stage hardening can be a limiting factor for life extension of nuclear power plants up to 80 or more years. The stability of the MNS precipitate was investigated from the thermodynamic view point and they concluded that MNS precipitate is a stable phase even with very little Cu contents, and they assessed UW1 thermodynamic database which can predict the thermodynamic stability of MNS precipitate at operating temperature of NPP ( ∼ 290 .deg. C). Based on the non-classical nucleation theory, we performed the phase-field modeling of nucleation and growth of MNS precipitate. The microstructure evolution of Mn-Ni-Cu precipitate has been simulated using the phase-field method and their approaches are focused on a role of the Cu contents. Also, a role of the interstitial loop on the nucleation and growth kinetics of MNS precipitate was analyzed.

On thermodynamics of AdS black holes in M-theory

International Nuclear Information System (INIS)

Belhaj, A.; Chabab, M.; Masmar, K.; El Moumni, H.; Sedra, M.B.

2016-01-01

Motivated by recent work on asymptotically AdS 4 black holes in M-theory, we investigate the thermodynamics and thermodynamical geometry of AdS black holes from M2- and M5-branes. Concretely, we consider AdS black holes in AdS p+2 x S 11-p-2 , where p = 2,5 by interpreting the number of M2- (and M5-branes) as a thermodynamical variable. More precisely, we study the corresponding phase transition to examine their stabilities by calculating and discussing various thermodynamical quantities including the chemical potential. Then we compute the thermodynamical curvatures from the Quevedo metric for M2- and M5-branes geometries to reconsider the stability of such black holes. The Quevedo metric singularities recover similar stability results provided by the phase-transition program. It has been shown that similar behaviors are also present in the limit of large N. (orig.)

Study on preparation and thermal property of binary fatty acid and the binary fatty acids/diatomite composite phase change materials

International Nuclear Information System (INIS)

Li, Min; Kao, Hongtao; Wu, Zhishen; Tan, Jinmiao

2011-01-01

This study prepared a series of binary phase change materials by mixing decanoic acid, dodecanoic acid, hexadecanoic acid and octadecanoic acid each other. The phase-transition temperature of binary fatty acid and its corresponding mixing proportion are calculated with phase diagram thermodynamic method. The results are verified by the experimental result of the heat absorption curve and the Differential Scanning Calorimetry (DSC) analysis curve. The results show that the calculation method of phase diagram thermodynamic calculation can be taken as a basis for mixing proportion of binary fatty acid phase change materials. In addition, the decanoic-dodecanoic acid/diatomite composite phase change material (PCM) are prepared and its microstructure, thermal property and thermal reliability are characterized. The result shows that the decanoic-dodecanoic acid is uniformly adsorbed into diatomite and the form-stable PCM are formed. The phase-transition temperature and the latent heat of the decanoic-dodecanoic acid/diatomite composite PCMs is 16.74 o C and 66.8114 J/g, respectively.

Modern Thermodynamics Based on the Extended Carnot Theorem

CERN Document Server

Wang, Jitao

2012-01-01

"Modern Thermodynamics- Based on the Extended Carnot Theorem" provides comprehensive definitions and mathematical expressions of both classical and modern thermodynamics. The goal is to develop the fundamental theory on an extended Carnot theorem without incorporating any extraneous assumptions. In particular, it offers a fundamental thermodynamic and calculational methodology for the synthesis of low-pressure diamonds. It also discusses many "abnormal phenomena", such as spiral reactions, cyclic reactions, chemical oscillations, low-pressure carat-size diamond growth, biological systems, and more. The book is intended for chemists and physicists working in thermodynamics, chemical thermodynamics, phase diagrams, biochemistry and complex systems, as well as graduate students in these fields. Jitao Wang is a professor emeritus at Fudan University, Shanghai, China.

DFT Study of Azole Corrosion Inhibitors on Cu2O Model of Oxidized Copper Surfaces: II. Lateral Interactions and Thermodynamic Stability

Directory of Open Access Journals (Sweden)

Dunja Gustinčič

2018-05-01

Full Text Available The adsorption of imidazole, triazole, and tetrazole—used as simple models of azole corrosion inhibitors—on various Cu 2 O(111- and Cu 2 O(110-type surfaces was characterized using density functional theory (DFT calculations with the focus on lateral intermolecular interactions and the thermodynamic stability of various adsorption structures. To this end, an ab initio thermodynamics approach was used to construct two-dimensional phase diagrams for all three molecules. The impact of van der Waals dispersion interactions on molecular adsorption bonding was also addressed. Lateral intermolecular interactions were found to be the most repulsive for imidazole and the least for tetrazole, for which they are usually even slightly attractive. Both non-dissociative and dissociative adsorption modes were considered and although dissociated molecules bind to surfaces more strongly, none of the considered structures that involve dissociated molecules appear on the phase diagrams. Our results show that the three azole molecules display a strong tendency to preferentially adsorb at reactive coordinatively unsaturated (CUS Cu surface sites and stabilize them. According to the calculated phase diagrams for Cu 2 O(111-type surfaces, the three azole molecules adsorb to specific CUS sites, designated as Cu CUS , under all conditions at which molecular adsorption is stable. This tentatively suggests that their corrosion inhibition capability may stem, at least in part, from their ability to passivate reactive surface sites. We further comment on a specific drawback due to neglect of configurational entropy that is usually utilized within the ab initio thermodynamics approach. We analyze the issue for Langmuir and Frumkin adsorption models and show that when configurational entropy is neglected, the ab initio thermodynamics approach is too hasty to predict phase-transition like behavior.

Thermodynamics of quark gas

Energy Technology Data Exchange (ETDEWEB)

Biswas, S. N.

1980-07-01

The application of quantum statistical mechanics to a system of particles consisting of quarks is considered. Realistic theoretical investigations have been underway to understand highly dense objects such as white dwarfs and neutron stars. The various possibilities in the case of very high densities such as 10/sup 15/ or 10/sup 16/ g/cm/sup 3/ are enumerated. The thermodynamics of a phase transition from neutron matter phase to quark matter phase is analysed. Preliminary results based on quantum chromodynamics and other phenomenological models are reported.

Thermodynamic properties of copper compounds with oxygen and hydrogen from first principles

Energy Technology Data Exchange (ETDEWEB)

Korzhavyi, P.A.; Johansson, B. (Applied Materials Physics, Dept. of Materials Science and Engineering, Royal Inst. of Technology, Stockholm (Sweden))

2010-02-15

We employ quantum-mechanical calculations (based on density functional theory and linear response theory) in order to test the mechanical and chemical stability of several solid-state configurations of Cu1+, Cu2+, O2-, H1-, and H1+ ions. We begin our analysis with cuprous oxide (Cu{sub 2}O, cuprite structure), cupric oxide (CuO, tenorite structure), and cuprous hydride (CuH, wurtzite and sphalerite structures) whose thermodynamic properties have been studied experimentally. In our calculations, all these compounds are found to be mechanically stable configurations. Their formation energies calculated at T = 0 K (including the energy of zero-point and thermal motion of the ions) and at room temperature are in good agreement with existing thermodynamic data. A search for other possible solid-state conformations of copper, hydrogen, and oxygen ions is then performed. Several candidate structures for solid phases of cuprous oxy-hydride (Cu{sub 4}H{sub 2}O) and cupric hydride (CuH{sub 2}) have been considered but found to be dynamically unstable. Cuprous oxy-hydride is found to be energetically unstable with respect to decomposition onto cuprous oxide and cuprous hydride. Metastability of cuprous hydroxide (CuOH) is established in our calculations. The free energy of CuOH is calculated to be some 50 kJ/mol higher than the average of the free energies of Cu{sub 2}O and water. Thus, cuprite Cu{sub 2}O is the most stable of the examined Cu(I) compounds

Thermodynamic properties of copper compounds with oxygen and hydrogen from first principles

International Nuclear Information System (INIS)

Korzhavyi, P.A.; Johansson, B.

2010-02-01

We employ quantum-mechanical calculations (based on density functional theory and linear response theory) in order to test the mechanical and chemical stability of several solid-state configurations of Cu 1+ , Cu 2+ , O 2- , H 1- , and H 1+ ions. We begin our analysis with cuprous oxide (Cu 2 O, cuprite structure), cupric oxide (CuO, tenorite structure), and cuprous hydride (CuH, wurtzite and sphalerite structures) whose thermodynamic properties have been studied experimentally. In our calculations, all these compounds are found to be mechanically stable configurations. Their formation energies calculated at T = 0 K (including the energy of zero-point and thermal motion of the ions) and at room temperature are in good agreement with existing thermodynamic data. A search for other possible solid-state conformations of copper, hydrogen, and oxygen ions is then performed. Several candidate structures for solid phases of cuprous oxy-hydride (Cu 4 H 2 O) and cupric hydride (CuH 2 ) have been considered but found to be dynamically unstable. Cuprous oxy-hydride is found to be energetically unstable with respect to decomposition onto cuprous oxide and cuprous hydride. Metastability of cuprous hydroxide (CuOH) is established in our calculations. The free energy of CuOH is calculated to be some 50 kJ/mol higher than the average of the free energies of Cu 2 O and water. Thus, cuprite Cu 2 O is the most stable of the examined Cu(I) compounds

On the thermodynamics of hairy black holes

Energy Technology Data Exchange (ETDEWEB)

Anabalón, Andrés [Departamento de Ciencias, Facultad de Artes Liberales y Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez, Viña del Mar (Chile); Astefanesei, Dumitru [Instituto de Física, Pontificia Universidad Católica de Valparaíso, Casilla 4059, Valparaíso (Chile); Choque, David, E-mail: brst1010123@gmail.com [Universidad Técnica Federico Santa María, Av. España 1680, Valparaiso (Chile)

2015-04-09

We investigate the thermodynamics of a general class of exact 4-dimensional asymptotically Anti-de Sitter hairy black hole solutions and show that, for a fixed temperature, there are small and large hairy black holes similar to the Schwarzschild–AdS black hole. The large black holes have positive specific heat and so they can be in equilibrium with a thermal bath of radiation at the Hawking temperature. The relevant thermodynamic quantities are computed by using the Hamiltonian formalism and counterterm method. We explicitly show that there are first order phase transitions similar to the Hawking–Page phase transition.

Thermodynamics, kinetics and process control of nitriding

DEFF Research Database (Denmark)

Mittemeijer, Eric J.; Somers, Marcel A. J.

1999-01-01

As a prerequisite for predictability of properties obtained by a nitriding treatment of iron-based workpieces, the relation between the process parameters and the composition and structure of the surface layer produced must be known. At present (even) the description of thermodynamic equilibrium...... of pure iron-nitrogen phases has not been achieved fully. It has been shown that taking into account ordering of nitrogen in the epsilon and gamma' iron-nitride phases, leads to an improved understanding of the Fe-N phase diagram. Although thermodynamics indicate the state the system strives for......, the nitriding result is determined largely by the kinetics of the process. The nitriding kinetics have been shown to be characterised by the occurring local near-equilibria and stationary states at surfaces and interfaces, and the diffusion coefficient of nitrogen in the various phases, for which new data have...

Thermodynamic modelling of Ag-Zn alloys

International Nuclear Information System (INIS)

Gomez-Acebo, T.; Sundman, B.

1998-01-01

A thermodynamic assessment of the Ag-Zn system has been done using a computerized CALPHAD (calculation of phase diagrams) technique. The liquid, α,β,ε and η phases are described by a regular solution model, the ζ phase by a two-sublattices model, and the γ phase by a four-sublattices model both based on considerations of their crystal structure and compatibility with the same phase in other systems. Some calculated phase and property diagrams are presented. (Author) 27 refs

Thermodynamic Tuning of Mg-Based Hydrogen Storage Alloys: A Review

Science.gov (United States)

Zhu, Min; Lu, Yanshan; Ouyang, Liuzhang; Wang, Hui

2013-01-01

Mg-based hydrides are one of the most promising hydrogen storage materials because of their relatively high storage capacity, abundance, and low cost. However, slow kinetics and stable thermodynamics hinder their practical application. In contrast to the substantial progress in the enhancement of the hydrogenation/dehydrogenation kinetics, thermodynamic tuning is still a great challenge for Mg-based alloys. At present, the main strategies to alter the thermodynamics of Mg/MgH2 are alloying, nanostructuring, and changing the reaction pathway. Using these approaches, thermodynamic tuning has been achieved to some extent, but it is still far from that required for practical application. In this article, we summarize the advantages and disadvantages of these strategies. Based on the current progress, finding reversible systems with high hydrogen capacity and effectively tailored reaction enthalpy offers a promising route for tuning the thermodynamics of Mg-based hydrogen storage alloys. PMID:28788353

Critical evaluation and thermodynamic optimization of the U-Pb and U-Sb binary systems

International Nuclear Information System (INIS)

Wang, Jian; Jin, Liling; Chen, Chuchu; Rao, Weifeng; Wang, Cuiping; Liu, Xingjun

2016-01-01

A complete literature review, critical evaluation and thermodynamic optimization of the phase diagrams and thermodynamic properties of U-Pb and U-Sb binary systems are presented. The CALculation of PHAse Diagrams (CALPHAD) method was used for the thermodynamic optimization, the results of which can reproduce all available reliable experimental phase equilibria and thermodynamic data. The modified quasi-chemical model in the pair approximation (MQMPA) was used for modeling the liquid solution. The Gibbs energies of all terminal solid solutions and intermetallic compounds were described by the compound energy formalism (CEF) model. All reliable experimental data of the U-Pb and U-Sb systems have been reproduced. A self-consistent thermodynamic database has been constructed for these binary systems; this database can be used in liquid-metal fuel reactor (LMFR) research.

Thermodynamic assessment of the CoOx-CrO1.5 system

DEFF Research Database (Denmark)

Östby, Jonas Allan; Chen, Ming

2009-01-01

By application of the CALPHAD method, a consistent set of thermodynamic model parameters is optimized for the oxide phases in the Co–Cr–O system. Cobalt chromium spinel is described as a normal spinel at room temperature and with cation redistribution at high temperature. All the solid oxide...... solution phases are described using the compound energy model, and the liquid phase is described using the two-sublattice model for ionic liquids. Calculated phase diagrams are presented, and values for the thermodynamic properties are compared with experimental data....

DERIVED THERMODYNAMIC PROPERTIES OF [o-XYLENE OR p ...

African Journals Online (AJOL)

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This paper is a continuation of our earlier work related to the study of thermodynamic properties of binary and ternary mixtures [1-6]. Reliable data on phase behavior and thermodynamic excess properties of multi component fluid mixtures are necessary for the proper design of synthesis and separation processes of the ...

Selecting polymers for two-phase partitioning bioreactors (TPPBs): Consideration of thermodynamic affinity, crystallinity, and glass transition temperature.

Science.gov (United States)

Bacon, Stuart L; Peterson, Eric C; Daugulis, Andrew J; Parent, J Scott

2015-01-01

Two-phase partitioning bioreactor technology involves the use of a secondary immiscible phase to lower the concentration of cytotoxic solutes in the fermentation broth to subinhibitory levels. Although polymeric absorbents have attracted recent interest due to their low cost and biocompatibility, material selection requires the consideration of properties beyond those of small molecule absorbents (i.e., immiscible organic solvents). These include a polymer's (1) thermodynamic affinity for the target compound, (2) degree of crystallinity (wc ), and (3) glass transition temperature (Tg ). We have examined the capability of three thermodynamic models to predict the partition coefficient (PC) for n-butyric acid, a fermentation product, in 15 polymers. Whereas PC predictions for amorphous materials had an average absolute deviation (AAD) of ≥16%, predictions for semicrystalline polymers were less accurate (AAD ≥ 30%). Prediction errors were associated with uncertainties in determining the degree of crystallinity within a polymer and the effect of absorbed water on n-butyric acid partitioning. Further complications were found to arise for semicrystalline polymers, wherein strongly interacting solutes increased the polymer's absorptive capacity by actually dissolving the crystalline fraction. Finally, we determined that diffusion limitations may occur for polymers operating near their Tg , and that the Tg can be reduced by plasticization by water and/or solute. This study has demonstrated the impact of basic material properties that affects the performance of polymers as sequestering phases in TPPBs, and reflects the additional complexity of polymers that must be taken into account in material selection. © 2015 American Institute of Chemical Engineers.

Statistical thermodynamics of clustered populations.

Science.gov (United States)

Matsoukas, Themis

2014-08-01

We present a thermodynamic theory for a generic population of M individuals distributed into N groups (clusters). We construct the ensemble of all distributions with fixed M and N, introduce a selection functional that embodies the physics that governs the population, and obtain the distribution that emerges in the scaling limit as the most probable among all distributions consistent with the given physics. We develop the thermodynamics of the ensemble and establish a rigorous mapping to regular thermodynamics. We treat the emergence of a so-called giant component as a formal phase transition and show that the criteria for its emergence are entirely analogous to the equilibrium conditions in molecular systems. We demonstrate the theory by an analytic model and confirm the predictions by Monte Carlo simulation.

Small Systems and Limitations on the Use of Chemical Thermodynamics

Science.gov (United States)

Tovbin, Yu. K.

2018-01-01

Limitations on using chemical thermodynamics to describe small systems are formulated. These limitations follow from statistical mechanics for equilibrium and nonequilibrium processes and reflect (1) differences between characteristic relaxation times in momentum, energy, and mass transfer in different aggregate states of investigated systems; (2) achievements of statistical mechanics that allow us to determine criteria for the size of smallest region in which thermodynamics can be applied and the scale of the emergence of a new phase, along with criteria for the conditions of violating a local equilibrium. Based on this analysis, the main thermodynamic results are clarified: the phase rule for distorted interfaces, the sense and area of applicability of Gibbs's concept of passive forces, and the artificiality of Kelvin's equation as a result of limitations on the thermodynamic approach to considering small bodies. The wrongness of introducing molecular parameters into thermodynamic derivations, and the activity coefficient for an activated complex into the expression for a reaction rate constant, is demonstrated.

On thermodynamics of AdS black holes in M-theory

Energy Technology Data Exchange (ETDEWEB)

Belhaj, A. [Universite Sultan Moulay Slimane, Departement de Physique, LIRST, Faculte Polydisciplinaire, Beni Mellal (Morocco); Cadi Ayyad University, High Energy Physics and Astrophysics Laboratory, FSSM, Marrakesh (Morocco); Chabab, M.; Masmar, K. [Cadi Ayyad University, High Energy Physics and Astrophysics Laboratory, FSSM, Marrakesh (Morocco); El Moumni, H. [Cadi Ayyad University, High Energy Physics and Astrophysics Laboratory, FSSM, Marrakesh (Morocco); Universite Ibn Zohr, Departement de Physique, Faculte des Sciences, Agadir (Morocco); Sedra, M.B. [Universite Ibn Tofail, Departement de Physique, LASIMO, Faculte des Sciences, Kenitra (Morocco)

2016-02-15

Motivated by recent work on asymptotically AdS{sub 4} black holes in M-theory, we investigate the thermodynamics and thermodynamical geometry of AdS black holes from M2- and M5-branes. Concretely, we consider AdS black holes in AdS{sub p+2} x S{sup 11-p-2}, where p = 2,5 by interpreting the number of M2- (and M5-branes) as a thermodynamical variable. More precisely, we study the corresponding phase transition to examine their stabilities by calculating and discussing various thermodynamical quantities including the chemical potential. Then we compute the thermodynamical curvatures from the Quevedo metric for M2- and M5-branes geometries to reconsider the stability of such black holes. The Quevedo metric singularities recover similar stability results provided by the phase-transition program. It has been shown that similar behaviors are also present in the limit of large N. (orig.)

Uhlenbeck-Ford model: Phase diagram and corresponding-states analysis

Science.gov (United States)

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

2017-09-01

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

Metallurgical features of the formation of a solid-phase metal joint upon electric-circuit heating

Science.gov (United States)

Latypov, R. A.; Bulychev, V. V.; Zybin, I. N.

2017-06-01

The thermodynamic conditions of formation of a joint between metals using the solid-phase methods of powder metallurgy, welding, and deposition of functional coatings upon electric-current heating of the surfaces to be joined are studied. Relations are obtained to quantitatively estimate the critical sizes of the circular and linear active centers that result in the formation of stable bonding zones.

Thermodynamic properties and atomic structure of Ca-based liquid alloys

Science.gov (United States)

Poizeau, Sophie

To identify the most promising positive electrodes for Ca-based liquid metal batteries, the thermodynamic properties of diverse Ca-based liquid alloys were investigated. The thermodynamic properties of Ca-Sb alloys were determined by emf measurements. It was found that Sb as positive electrode would provide the highest voltage for Ca-based liquid metal batteries (1 V). The price of such a battery would be competitive for the grid-scale energy storage market. The impact of Pb, a natural impurity of Sb, was predicted successfully and confirmed via electrochemical measurements. It was shown that the impact on the open circuit voltage would be minor. Indeed, the interaction between Ca and Sb was demonstrated to be much stronger than between Ca and Pb using thermodynamic modeling, which explains why the partial thermodynamic properties of Ca would not vary much with the addition of Pb to Sb. However, the usage of the positive electrode would be reduced, which would limit the interest of a Pb-Sb positive electrode. Throughout this work, the molecular interaction volume model (MIVM) was used for the first time for alloys with thermodynamic properties showing strong negative deviation from ideality. This model showed that systems such as Ca-Sb have strong short-range order: Ca is most stable when its first nearest neighbors are Sb. This is consistent with what the more traditional thermodynamic model, the regular association model, would predict. The advantages of the MIVM are the absence of assumption regarding the composition of an associate, and the reduced number of fitting parameters (2 instead of 5). Based on the parameters derived from the thermodynamic modeling using the MIVM, a new potential of mixing for liquid alloys was defined to compare the strength of interaction in different Ca-based alloys. Comparing this trend with the strength of interaction in the solid state of these systems (assessed by the energy of formation of the intermetallics), the systems with

Thermodynamical and dynamical properties of charged BTZ black holes

Energy Technology Data Exchange (ETDEWEB)

Tang, Zi-Yu; Wang, Bin [Shanghai Jiao Tong University, Department of Physics and Astronomy, Center for Astronomy and Astrophysics, Shanghai (China); Zhang, Cheng-Yong [Peking University, Center for High-Energy Physics, Beijing (China); Kord Zangeneh, Mahdi [Shanghai Jiao Tong University, Department of Physics and Astronomy, Center for Astronomy and Astrophysics, Shanghai (China); Shahid Chamran University of Ahvaz, Physics Department, Faculty of Science, Ahvaz (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM)-Maragha, P. O. Box: 55134-441, Maragha (Iran, Islamic Republic of); Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of); Saavedra, Joel [Pontificia Universidad Catolica de Valparaiso, Instituto de Fisica, Valparaiso (Chile)

2017-06-15

We investigate the spacetime properties of BTZ black holes in the presence of the Maxwell field and Born-Infeld field and find rich properties in the spacetime structures when the model parameters are varied. Employing Landau-Lifshitz theory, we examine the thermodynamical phase transition in the charged BTZ black holes. We further study the dynamical perturbation in the background of the charged BTZ black holes and find different properties in the dynamics when the thermodynamical phase transition occurs. (orig.)

Thermodynamic investigations in the system U-Mo-O

International Nuclear Information System (INIS)

Chattopadhyay, G.; Kerkar, A.S.; Tripathi, S.N.

1984-01-01

Thermodynamic data on materials are required to answer some practical questions regarding chemical equilibria and also for the ultimate purpose of quantifying the relative stabilities of all possible chemical species. The present work was undertaken to determine what role molybdenum, one of the most preponderant fission products, could play in determining the state of the chemical equilibrium in the fuel fission product complex in an oxide-based nuclear reactor or in the nuclear waste disposed in ceramic or glass forms. To understand and analyze such complex systems, it is necessary to know which are the possible phases and species that are to be considered and their thermodynamic properties. In the present work attention was given to the ternary oxides of uranium and molybdenum with regard to the equilibria among the various phases. This is a prerequisite for determining the thermodynamic properties of the relevant phases. Therefore, experiments were carried out to construct the phase diagram in the region UO 2 -MoO 2 -O in a more precise manner than hitherto and, hence, to determine the free energy of formation of UMoO 5

Thermodynamic assessment of the Nb-W-C system

International Nuclear Information System (INIS)

Huang Weiming; Selleby, M.

1997-01-01

The phase equilibrium and thermodynamic information of the Nb-W-C system was reviewed and assessed by using thermodynamic models for the Gibbs energy of individual phases. The assessment was based on the recent evaluations of the W-C, Nb-W and Nb-C, which was revised in the present work taking ternary information into account. The model parameters were evaluated by fitting the selected experimental data by means of a computer program. A consistent set of parameters was obtained, which satisfactorily describes most of the experimental information. (orig.)

Thermodynamics analysis of the rare earth metals and their alloys with indium in solid state

International Nuclear Information System (INIS)

Vassiliev, V.P.; Benaissa, Ablazeze; Taldrik, A.F.

2013-01-01

Graphical abstract: Gibbs energies of formation vs. RE atomic numbers in REIn 3 . Highlights: •Set of experimental values was collected for REIn 3 phases. •Thermodynamic functions of formation were calculated at 298 K and 775 K. •Experimental and calculated values were compared. -- Abstract: Nonlinear correlative analyses between thermodynamic and some physico-chemical properties of rare-earth metals (RE) and their alloys with indium are performed for the isostructural phases RE and REIn 3 . The thermodynamics values (Gibbs energies of formation, enthalpies of formation, and entropies of formation at 298 K and 775 K and standard entropies) of LnIn 3 phases are calculated on the basis of calorimetry and potentiometry results. The proposed correlation between physico-chemical and thermodynamic properties agrees for all the isostructural phases REX (X are others elements of the periodic table). The resulting thermodynamic data are recommended for metallurgical handbook

Modern thermodynamics. Based on the extended Carnot theorem

Energy Technology Data Exchange (ETDEWEB)

Wang, Jitao [Fudan Univ., Shanghai (China). Microelectronics Dept.

2011-07-01

''Modern Thermodynamics- Based on the Extended Carnot Theorem'' provides comprehensive definitions and mathematical expressions of both classical and modern thermodynamics. The goal is to develop the fundamental theory on an extended Carnot theorem without incorporating any extraneous assumptions. In particular, it offers a fundamental thermodynamic and calculational methodology for the synthesis of low-pressure diamonds. It also discusses many ''abnormal phenomena'', such as spiral reactions, cyclic reactions, chemical oscillations, low-pressure carat-size diamond growth, biological systems, and more. The book is intended for chemists and physicists working in thermodynamics, chemical thermodynamics, phase diagrams, biochemistry and complex systems, as well as graduate students in these fields. Jitao Wang is a professor emeritus at Fudan University, Shanghai, China. (orig.)

Chlorine Evolution Reaction on RuO2(110): Ab initio Atomistic Thermodynamics Study - Pourbaix Diagrams

International Nuclear Information System (INIS)

Exner, Kai S.; Anton, Josef; Jacob, Timo; Over, Herbert

2014-01-01

Graphical abstract: - Highlights: • Using the method Pourbaix diagram we identified the oxygen covered RuO 2 (110) surface as the catalytically active phase under chlorine evolution reaction (CER) conditions. This active phase is compared with the active phase in the Deacon process, the heterogeneous gas phase counterpart of the CER. - Abstract: Constrained ab initio thermodynamics in the form of a Pourbaix diagram can greatly assist kinetic modeling of a particular electrochemical reaction such as the chlorine evolution reaction (CER) over RuO 2 (110). Pourbaix diagrams reveal stable surface structures, as a function of pH and the potential. The present DFT study indicates that the Pourbaix diagram in the CER potential region above 1.36 V and pH values around zero is dominated by a stable surface structure in which all coordinatively undercoordinated Ru sites (Ru cus ) are capped by on-top oxygen (O ot ). This oxygen saturated RuO 2 (110) surface is considered to serve as the catalytically active phase in the CER, quite in contrast to the heterogeneously catalyzed HCl oxidation (Deacon process), for which the active RuO 2 (110) surface is mainly covered by on-top chlorine. The active sites in the CER are suggested to be Ru cus O ot surface complexes, while in the Deacon process both undercoordinated surface Ru and oxygen sites must be available for the activation of HCl molecules

A New Thermodynamics from Nuclei to Stars

Directory of Open Access Journals (Sweden)

Dieter H.E. Gross

2004-03-01

Full Text Available Abstract: Equilibrium statistics of Hamiltonian systems is correctly described by the microcanonical ensemble. Classically this is the manifold of all points in the N-body phase space with the given total energy. Due to Boltzmann's principle, eS=tr(δ(E-H, its geometrical size is related to the entropy S(E,N,.... This definition does not invoke any information theory, no thermodynamic limit, no extensivity, and no homogeneity assumption, as are needed in conventional (canonical thermo-statistics. Therefore, it describes the equilibrium statistics of extensive as well of non-extensive systems. Due to this fact it is the fundamental definition of any classical equilibrium statistics. It can address nuclei and astrophysical objects as well. All kind of phase transitions can be distinguished sharply and uniquely for even small systems. It is further shown that the second law is a natural consequence of the statistical nature of thermodynamics which describes all systems with the same -- redundant -- set of few control parameters simultaneously. It has nothing to do with the thermodynamic limit. It even works in systems which are by far than any thermodynamic "limit".

Phases of Ca from first principles

International Nuclear Information System (INIS)

Qiu, S L; Marcus, P M

2009-01-01

Structures and properties of many of the phases of Ca under pressure are calculated from first principles by a systematic procedure that minimizes total energy E with respect to structure under the constraint of constant volume V. The minima of E are followed on successive sweeps of lattice parameters for 11 of 14 Bravais symmetries for one-atom-per-cell structures. The structures include the four orthorhombic phases. Also included are the hexagonal close-packed and cubic diamond phases with two atoms per primitive cell. No uniquely orthorhombic phases are found; all one-atom orthorhombic phases over a mega-bar pressure range are identical to higher-symmetry phases. The simple cubic phase is shown to be stable where it is the ground state. The number of distinct one-atom phases reduces to five plus the two two-atom phases. For each of these phases the Gibbs free energy at pressure p, G(p), is calculated for a non-vibrating lattice; the functions G(p) give the ground state at each p, the relative stabilities of all phases and the thermodynamic phase transition pressures for all phase transitions over a several-megabar range.

Phase-locked 3D3C-MRV measurements in a bi-stable fluidic oscillator

Science.gov (United States)

Wassermann, Florian; Hecker, Daniel; Jung, Bernd; Markl, Michael; Seifert, Avi; Grundmann, Sven

2013-03-01

In this work, the phase-resolved internal flow of a bi-stable fluidic oscillator was measured using phase-locked three-dimensional three-components magnetic resonance velocimetry (3D3C-MRV), also termed as 4D-MRV. A bi-stable fluidic oscillator converts a continuous inlet-mass flow into a jet alternating between two outlet channels and, as a consequence provides an unsteady, periodic flow. This actuator can therefore be used as flow-control actuator. Since data acquisition in a 3D volume takes up to several minutes, only a small portion of the data is acquired in each flow cycle for every time point of the flow cycle. The acquisition of the entire data set is segmented over many cycles of the periodic flow. This procedure allows to measure phase-averaged 3D3C velocity fields with a certain temporal resolution. However, the procedure requires triggering to the periodic nature of the flow. Triggering the MR scanner precisely on each flow cycle is one of the key issues discussed in this manuscript. The 4D-MRV data are compared to data measured using phase-locked laser Doppler anemometry and good agreement between the results is found. The validated 4D-MRV data is analyzed and the fluid-mechanic features and processes inside the fluidic oscillator are investigated and described, providing a detailed description of the internal jet-switching mechanism.

Thermodynamics phase transition and Hawking radiation of the Schwarzschild black hole with quintessence-like matter and a deficit solid angle

Science.gov (United States)

Rodrigue, Kamiko Kouemeni Jean; Saleh, Mahamat; Thomas, Bouetou Bouetou; Kofane, Timoleon Crepin

2018-05-01

In this paper, we investigate the thermodynamics and Hawking radiation of Schwarzschild black hole with quintessence-like matter and deficit solid angle. From the metric of the black hole, we derive the expressions of temperature and specific heat using the laws of black hole thermodynamics. Using the null geodesics method and Parikh-Wilczeck tunneling method, we derive the expressions of Boltzmann factor and the change of Bekenstein-Hawking entropy for the black hole. The behaviors of the temperature, specific heat, Boltzmann factor and the change of Bekenstein entropy versus the deficit solid angle (ɛ 2) and the density of static spherically symmetric quintessence-like matter (ρ 0) were explicitly plotted. The results show that, when the deficit solid angle (ɛ 2) and the density of static spherically symmetric quintessence-like matter at r=1 (ρ 0) vanish (ρ 0=ɛ =0), these four thermodynamics quantities are reduced to those obtained for the simple case of Schwarzschild black hole. For low entropies, the presence of quintessence-like matter induces a first order phase transition of the black hole and for the higher values of the entropies, we observe the second order phase transition. When increasing ρ 0, the transition points are shifted to lower entropies. The same thing is observed when increasing ɛ 2. In the absence of quintessence-like matter (ρ 0=0), these transition phenomena disappear. Moreover the rate of radiation decreases when increasing ρ 0 or (ɛ ^2).

Vapor-deposited non-crystalline phase vs ordinary glasses and supercooled liquids: Subtle thermodynamic and kinetic differences

International Nuclear Information System (INIS)

Bhattacharya, Deepanjan; Sadtchenko, Vlad

2015-01-01

Vapor deposition of molecules on a substrate often results in glassy materials of high kinetic stability and low enthalpy. The extraordinary properties of such glasses are attributed to high rates of surface diffusion during sample deposition, which makes it possible for constituents to find a configuration of much lower energy on a typical laboratory time scale. However, the exact nature of the resulting phase and the mechanism of its formation are not completely understood. Using fast scanning calorimetry technique, we show that out-of-equilibrium relaxation kinetics and possibly the enthalpy of vapor-deposited films of toluene and ethylbenzene, archetypical fragile glass formers, are distinct from those of ordinary supercooled phase even when the deposition takes place at temperatures above the ordinary glass softening transition temperatures. These observations along with the absolute enthalpy dependences on deposition temperatures support the conjecture that the vapor-deposition may result in formation of non-crystalline phase of unique structural, thermodynamic, and kinetic properties

Irreversible thermodynamic analysis and application for molecular heat engines

Science.gov (United States)

Lucia, Umberto; Açıkkalp, Emin

2017-09-01

Is there a link between the macroscopic approach to irreversibility and microscopic behaviour of the systems? Consumption of free energy keeps the system away from a stable equilibrium. Entropy generation results from the redistribution of energy, momentum, mass and charge. This concept represents the essence of the thermodynamic approach to irreversibility. Irreversibility is the result of the interaction between systems and their environment. The aim of this paper is to determine lost works in a molecular engine and compare results with macro (classical) heat engines. Firstly, irreversible thermodynamics are reviewed for macro and molecular cycles. Secondly, irreversible thermodynamics approaches are applied for a quantum heat engine with -1/2 spin system. Finally, lost works are determined for considered system and results show that macro and molecular heat engines obey same limitations. Moreover, a quantum thermodynamic approach is suggested in order to explain the results previously obtained from an atomic viewpoint.

In search of the best match: probing a multi-dimensional cloud microphysical parameter space to better understand what controls cloud thermodynamic phase

Science.gov (United States)

Tan, Ivy; Storelvmo, Trude

2015-04-01

Substantial improvements have been made to the cloud microphysical schemes used in the latest generation of global climate models (GCMs), however, an outstanding weakness of these schemes lies in the arbitrariness of their tuning parameters, which are also notoriously fraught with uncertainties. Despite the growing effort in improving the cloud microphysical schemes in GCMs, most of this effort has neglected to focus on improving the ability of GCMs to accurately simulate the present-day global distribution of thermodynamic phase partitioning in mixed-phase clouds. Liquid droplets and ice crystals not only influence the Earth's radiative budget and hence climate sensitivity via their contrasting optical properties, but also through the effects of their lifetimes in the atmosphere. The current study employs NCAR's CAM5.1, and uses observations of cloud phase obtained by NASA's CALIOP lidar over a 79-month period (November 2007 to June 2014) guide the accurate simulation of the global distribution of mixed-phase clouds in 20∘ latitudinal bands at the -10∘ C, -20∘C and -30∘C isotherms, by adjusting six relevant cloud microphysical tuning parameters in the CAM5.1 via Quasi-Monte Carlo sampling. Among the parameters include those that control the Wegener-Bergeron-Findeisen (WBF) timescale for the conversion of supercooled liquid droplets to ice and snow in mixed-phase clouds, the fraction of ice nuclei that nucleate ice in the atmosphere, ice crystal sedimentation speed, and wet scavenging in stratiform and convective clouds. Using a Generalized Linear Model as a variance-based sensitivity analysis, the relative contributions of each of the six parameters are quantified to gain a better understanding of the importance of their individual and two-way interaction effects on the liquid to ice proportion in mixed-phase clouds. Thus, the methodology implemented in the current study aims to search for the combination of cloud microphysical parameters in a GCM that

CTserver: A Computational Thermodynamics Server for the Geoscience Community

Science.gov (United States)

Kress, V. C.; Ghiorso, M. S.

2006-12-01

The CTserver platform is an Internet-based computational resource that provides on-demand services in Computational Thermodynamics (CT) to a diverse geoscience user base. This NSF-supported resource can be accessed at ctserver.ofm-research.org. The CTserver infrastructure leverages a high-quality and rigorously tested software library of routines for computing equilibrium phase assemblages and for evaluating internally consistent thermodynamic properties of materials, e.g. mineral solid solutions and a variety of geological fluids, including magmas. Thermodynamic models are currently available for 167 phases. Recent additions include Duan, Møller and Weare's model for supercritical C-O-H-S, extended to include SO2 and S2 species, and an entirely new associated solution model for O-S-Fe-Ni sulfide liquids. This software library is accessed via the CORBA Internet protocol for client-server communication. CORBA provides a standardized, object-oriented, language and platform independent, fast, low-bandwidth interface to phase property modules running on the server cluster. Network transport, language translation and resource allocation are handled by the CORBA interface. Users access server functionality in two principal ways. Clients written as browser- based Java applets may be downloaded which provide specific functionality such as retrieval of thermodynamic properties of phases, computation of phase equilibria for systems of specified composition, or modeling the evolution of these systems along some particular reaction path. This level of user interaction requires minimal programming effort and is ideal for classroom use. A more universal and flexible mode of CTserver access involves making remote procedure calls from user programs directly to the server public interface. The CTserver infrastructure relieves the user of the burden of implementing and testing the often complex thermodynamic models of real liquids and solids. A pilot application of this distributed