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Sample records for thermodynamic phase-stability calculations

  1. Thermodynamic and experimental study on phase stability in nanocrystalline alloys

    International Nuclear Information System (INIS)

    Xu Wenwu; Song Xiaoyan; Lu Nianduan; Huang Chuan

    2010-01-01

    Nanocrystalline alloys exhibit apparently different phase transformation characteristics in comparison to the conventional polycrystalline alloys. The special phase stability and phase transformation behavior, as well as the essential mechanisms of the nanocrystalline alloys, were described quantitatively in a nanothermodynamic point of view. By introducing the relationship between the excess volume at the grain boundary and the nanograin size, the Gibbs free energy was determined distinctly as a function of temperature and the nanograin size. Accordingly, the grain-size-dependence of the phase stability and phase transformation characteristics of the nanocrystalline alloy were calculated systematically, and the correlations between the phase constitution, the phase transformation temperature and the critical nanograin size were predicted. A series of experiments was performed to investigate the phase transformations at room temperature and high temperatures using the nanocrystalline Sm 2 Co 17 alloy as an example. The phase constitution and phase transformation sequence found in nanocrystalline Sm 2 Co 17 alloys with various grain-size levels agree well with the calculations by the nanothermodynamic model.

  2. First-principles thermodynamics study of phase stability in inorganic halide perovskite solid solutions

    Science.gov (United States)

    Bechtel, Jonathon S.; Van der Ven, Anton

    2018-04-01

    Halide substitution gives rise to a tunable band gap as a function of composition in halide perovskite materials. However, photoinduced phase segregation, observed at room temperature in mixed halide A Pb (IxBr1-x) 3 systems, limits open circuit voltages and decreases photovoltaic device efficiencies. We investigate equilibrium phase stability of orthorhombic P n m a γ -phase CsM (XxY1-x) 3 perovskites where M is Pb or Sn, and X and Y are Br, Cl, or I. Finite-temperature phase diagrams are constructed using a cluster expansion effective Hamiltonian parameterized from first-principles density-functional-theory calculations. Solid solution phases for CsM (IxBr1-x) 3 and CsM (BrxCl1-x) 3 are predicted to be stable well below room temperature while CsM (IxCl1-x) 3 systems have miscibility gaps that extend above 400 K. The height of the miscibility gap correlates with the difference in volume between end members. Also layered ground states are found on the convex hull at x =2 /3 for CsSnBr2Cl ,CsPbI2Br , and CsPbBrCl2. The impact of these ground states on the finite temperature phase diagram is discussed in the context of the experimentally observed photoinduced phase segregation.

  3. 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

  4. 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

  5. Thermodynamic modeling and experimental investigation of the phase stability at the Ni-rich region of the Ni-Al-Cr-Ir system

    International Nuclear Information System (INIS)

    Zhang, C.; Zhang, F.; Chen, S.-L.; Cao, W.-S.; Chang, Y.A.

    2011-01-01

    The effect of adding 3 at.% Cr on the phase stability of the Ni-Al-Ir system was studied experimentally at 1250 deg. C. A thermodynamic description of the Ni-Al-Cr-Ir quaternary system in the Ni-rich region was then developed based on the microstructures, the crystal structures and the phase compositions determined by experiment for eight alloys in both as-cast and 1250 deg. C annealed states. The calculated isothermal section at 1250 deg. C using the obtained description was consistent with the phase-equilibrium data obtained in this study. The calculated two-dimensional section of liquidus projection was also in accordance with the primary phases of solidification observed from alloys in the as-cast state. The effects of Cr additions to the Ni-Al-Ir alloys on the as-cast and annealed microstructures were elucidated through Scheil simulation and phase-equilibrium calculation using Pandat.

  6. Bulk and Interface Thermodynamics of Calcia-, and Yttria-doped Zirconia Ceramics: Nanograined Phase Stability

    Science.gov (United States)

    Drazin, John Walter

    while simultaneously collecting the energetic contribution of the adsorbing water vapor. With this data and apparatus, I have derived a 2nd order differential equation that relates the surface energy to the measured quantities such that I collected surfaces energies for over 35 specimens in the calcia-zirconia and yttria-zirconia systems for the first time. From the results, it was found that the monoclinic polymorph had the largest surface energy in the range of 1.9 - 2.1 ( J/m2) while the tetragonal surface energies were roughly 1.4 - 1.6 (J/m2), the cubic surface energies were roughly 0.8 - 1.0 (J/m2), and the amorphous surface energies were the smallest at roughly 0.7 - 0.8 (J/m 2). With the measured surface energy data, collected for the first time, we can create a nano-grain phase diagram similar to a bulk phase diagram that shows the stable polymorph as a function of dopant concentration and grain size using the bulk enthalpy data collected from high temperature oxide melt drop solution calorimetry. The phase diagrams show that pure zirconia will transform into tetragonal and cubic polymorphs from the monoclinic one at 7 and 5 nm respectively which confirms the experimental observations. The results are powerful predictive tools successfully applied in the nCZ and nYZ systems to a high degree of accuracy and adds a new development to conventional bulk phase diagrams. These diagrams should be the basis for nanotechnological efforts in nCZ and nYZ based systems, and suggest similar efforts are needed in other nano systems to pursue an in depth understanding and optimization of nanomaterials. After working on the theoretical aspects of phase stability, the focus of the research will shift to producing dense samples to measure observable quantities such as oxygen conduction and mechanical hardness. However, producing said samples with the nanocrystalline grain sizes has also been challenging as conventional sintering requires high temperatures which, as a consequence

  7. Site preference and phase stability of Ti doping Ni–Mn–Ga shape memory alloys from first-principles calculations

    International Nuclear Information System (INIS)

    Gao, Zhiyong; Chen, Baishu; Meng, Xianglong; Cai, Wei

    2013-01-01

    Highlights: •Site preference and phase stability of NiMnGaTi are studied by first-principles. •The Ti atoms prefer to occupy the Ga sites in the Ni 2 MnGa austenitic phase. •The phase stability becomes worse when Ga is replaced by Ti. •The phase stability is discussed based on the densities of states. -- Abstract: The effects of Ti content on martensitic transformation and phase stability of Ni 50 Mn 25 Ga 25−x Ti x shape memory alloys were investigated from first-principles calculations based on density functional theory. The formation energy results indicate that the added Ti preferentially occupies the Ga sites in Ni 2 MnGa alloy due to the lowest formation energy. The total energy difference between austenite and martensite increases with Ti alloying, being relevant to the experimentally reported changes in martensitic transformation temperature. The phase stability of Ni 50 Mn 25 Ga 25−x Ti x austenite decreases with increasing Ti content, which results from the reduced Ni 3d–Mn 3d hybridization when Ga is replaced by Ti

  8. 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...

  9. 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.

  10. Solid phase stability of molybdenum under compression: Sound velocity measurements and first-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiulu [Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, P.O. Box 919-102, 621900 Mianyang, Sichuan (China); Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology, 621010 Mianyang, Sichuan (China); Liu, Zhongli [Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, P.O. Box 919-102, 621900 Mianyang, Sichuan (China); College of Physics and Electric Information, Luoyang Normal University, 471022 Luoyang, Henan (China); Jin, Ke; Xi, Feng; Yu, Yuying; Tan, Ye; Dai, Chengda; Cai, Lingcang [Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, P.O. Box 919-102, 621900 Mianyang, Sichuan (China)

    2015-02-07

    The high-pressure solid phase stability of molybdenum (Mo) has been the center of a long-standing controversy on its high-pressure melting. In this work, experimental and theoretical researches have been conducted to check its solid phase stability under compression. First, we performed sound velocity measurements from 38 to 160 GPa using the two-stage light gas gun and explosive loading in backward- and forward-impact geometries, along with the high-precision velocity interferometry. From the sound velocities, we found no solid-solid phase transition in Mo before shock melting, which does not support the previous solid-solid phase transition conclusion inferred from the sharp drops of the longitudinal sound velocity [Hixson et al., Phys. Rev. Lett. 62, 637 (1989)]. Then, we searched its structures globally using the multi-algorithm collaborative crystal structure prediction technique combined with the density functional theory. By comparing the enthalpies of body centered cubic structure with those of the metastable structures, we found that bcc is the most stable structure in the range of 0–300 GPa. The present theoretical results together with previous ones greatly support our experimental conclusions.

  11. eQuilibrator--the biochemical thermodynamics calculator.

    Science.gov (United States)

    Flamholz, Avi; Noor, Elad; Bar-Even, Arren; Milo, Ron

    2012-01-01

    The laws of thermodynamics constrain the action of biochemical systems. However, thermodynamic data on biochemical compounds can be difficult to find and is cumbersome to perform calculations with manually. Even simple thermodynamic questions like 'how much Gibbs energy is released by ATP hydrolysis at pH 5?' are complicated excessively by the search for accurate data. To address this problem, eQuilibrator couples a comprehensive and accurate database of thermodynamic properties of biochemical compounds and reactions with a simple and powerful online search and calculation interface. The web interface to eQuilibrator (http://equilibrator.weizmann.ac.il) enables easy calculation of Gibbs energies of compounds and reactions given arbitrary pH, ionic strength and metabolite concentrations. The eQuilibrator code is open-source and all thermodynamic source data are freely downloadable in standard formats. Here we describe the database characteristics and implementation and demonstrate its use.

  12. eQuilibrator—the biochemical thermodynamics calculator

    Science.gov (United States)

    Flamholz, Avi; Noor, Elad; Bar-Even, Arren; Milo, Ron

    2012-01-01

    The laws of thermodynamics constrain the action of biochemical systems. However, thermodynamic data on biochemical compounds can be difficult to find and is cumbersome to perform calculations with manually. Even simple thermodynamic questions like ‘how much Gibbs energy is released by ATP hydrolysis at pH 5?’ are complicated excessively by the search for accurate data. To address this problem, eQuilibrator couples a comprehensive and accurate database of thermodynamic properties of biochemical compounds and reactions with a simple and powerful online search and calculation interface. The web interface to eQuilibrator (http://equilibrator.weizmann.ac.il) enables easy calculation of Gibbs energies of compounds and reactions given arbitrary pH, ionic strength and metabolite concentrations. The eQuilibrator code is open-source and all thermodynamic source data are freely downloadable in standard formats. Here we describe the database characteristics and implementation and demonstrate its use. PMID:22064852

  13. Structural, phase stability, electronic, elastic properties and hardness of IrN{sub 2} and zinc blende IrN: First-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Zhaobo [Key Laboratory of Advanced Materials of Yunnan Province & Key Laboratory of Advanced Materials of Non-Ferrous and Precious Rare Metals Ministry of Education, Kunming University of Science and Technology, Kunming 650093 (China); Zhou, Xiaolong, E-mail: kmzxlong@163.com [Key Laboratory of Advanced Materials of Yunnan Province & Key Laboratory of Advanced Materials of Non-Ferrous and Precious Rare Metals Ministry of Education, Kunming University of Science and Technology, Kunming 650093 (China); Zhang, Kunhua [State Key Laboratory of Rare Precious Metals Comprehensive Utilization of New Technologies, Kunming Institute of Precious Metals, Kunming 650106 (China)

    2016-12-15

    First-principle calculations were performed to investigate the structural, phase stability, electronic, elastic properties and hardness of monoclinic structure IrN{sub 2} (m-IrN{sub 2}), orthorhombic structure IrN{sub 2} (o-IrN{sub 2}) and zinc blende structure IrN (ZB IrN). The results show us that only m-IrN{sub 2} is both thermodynamic and dynamic stability. The calculated band structure and density of states (DOS) curves indicate that o-IrN{sub 2} and ZB Ir-N compounds we calculated have metallic behavior while m-IrN{sub 2} has a small band gap of ~0.3 eV, and exist a common hybridization between Ir-5d and N-2p states, which forming covalent bonding between Ir and N atoms. The difference charge density reveals the electron transfer from Ir atom to N atom for three Ir-N compounds, which forming strong directional covalent bonds. Notable, a strong N-N bond appeared in m-IrN{sub 2} and o-IrN{sub 2}. The ratio of bulk to shear modulus (B/G) indicate that three Ir-N compounds we calculated are ductile, and ZB IrN possesses a better ductility than two types IrN{sub 2}. m-IrN{sub 2} has highest Debye temperature (736 K), illustrating it possesses strongest covalent bonding. The hardness of three Ir-N compounds were also calculated, and the results reveal that m-IrN{sub 2} (18.23 GPa) and o-IrN{sub 2} (18.02 GPa) are ultraincompressible while ZB IrN has a negative value, which may be attributed to phase transition at ca. 1.98 GPa.

  14. 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.

  15. 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.

  16. Phase stability, electronic structure and equation of state of cubic TcN from first-principles calculations

    International Nuclear Information System (INIS)

    Song, T.; Ma, Q.; Sun, X.W.; Liu, Z.J.; Fu, Z.J.; Wei, X.P.; Wang, T.; Tian, J.H.

    2016-01-01

    The phase transition, electronic band structure, and equation of state (EOS) of cubic TcN are investigated by first-principles pseudopotential method based on density-functional theory. The calculated enthalpies show that TcN has a transformation between zincblende and rocksalt phases and the pressure determined by the relative enthalpy is 32 GPa. The calculated band structure indicates the metallic feature and it might make cubic TcN a better candidate for hard materials. Particular attention is paid to the predictions of volume, bulk modulus and its pressure derivative which play a central role in the formulation of approximate EOSs using the quasi-harmonic Debye model. - Highlights: • The phase transition pressure and electronic band structure for cubic TcN are determined. • Particular attention is paid to investigate the equation of state parameters for cubic TcN. • The thermodynamic properties up to 80 GPa and 3000 K are successfully predicted.

  17. Thermodynamic calculation on the stability of (Fe,Mn){sub 3}AlC carbide in high aluminum steels

    Energy Technology Data Exchange (ETDEWEB)

    Chin, Kwang-Geun [Automotive Steel Products Research Group, POSCO Technical Research Laboratories, POSCO, Jeonnam 545-090 (Korea, Republic of); School of Materials Science and Engineering, Pusan National University, Pusan, 609-735 (Korea, Republic of); Lee, Hyuk-Joong [Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784 (Korea, Republic of); Kwak, Jai-Hyun [Automotive Steel Products Research Group, POSCO Technical Research Laboratories, POSCO, Jeonnam 545-090 (Korea, Republic of); Kang, Jung-Yoon [School of Materials Science and Engineering, Pusan National University, Pusan, 609-735 (Korea, Republic of); Lee, Byeong-Joo, E-mail: calphad@postech.ac.k [Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784 (Korea, Republic of)

    2010-08-27

    A CALPHAD type thermodynamic description for the Fe-Mn-Al-C quaternary system has been constructed by combining a newly assessed Mn-Al-C ternary description and a partly modified Fe-Al-C description to an existing thermodynamic database for steels. A special attention was paid to reproduce experimentally reported phase stability of {kappa} carbide in high Al and high Mn steels. This paper demonstrates that the proposed thermodynamic description makes it possible to predict phase equilibria in corresponding alloys with a practically acceptable accuracy. The applicability of the thermodynamic calculation is also demonstrated for the interpretation of microstructural and constitutional evolution during industrial processes for high Al steels.

  18. Thermodynamic calculation on the stability of (Fe,Mn)3AlC carbide in high aluminum steels

    International Nuclear Information System (INIS)

    Chin, Kwang-Geun; Lee, Hyuk-Joong; Kwak, Jai-Hyun; Kang, Jung-Yoon; Lee, Byeong-Joo

    2010-01-01

    A CALPHAD type thermodynamic description for the Fe-Mn-Al-C quaternary system has been constructed by combining a newly assessed Mn-Al-C ternary description and a partly modified Fe-Al-C description to an existing thermodynamic database for steels. A special attention was paid to reproduce experimentally reported phase stability of κ carbide in high Al and high Mn steels. This paper demonstrates that the proposed thermodynamic description makes it possible to predict phase equilibria in corresponding alloys with a practically acceptable accuracy. The applicability of the thermodynamic calculation is also demonstrated for the interpretation of microstructural and constitutional evolution during industrial processes for high Al steels.

  19. Thermodynamic calculation of a district energy cycle

    International Nuclear Information System (INIS)

    Hoehlein, B.; Bauer, A.; Kraut, G.; Scherberich, F.D.

    1975-08-01

    This paper presents a calculation model for a nuclear district energy circuit. Such a circuit means the combination of a steam reforming plant with heat supply from a high-temperature nuclear reactor and a methanation plant with heat production for district heating or electricity production. The model comprises thermodynamic calculations for the endothermic methane reforming reaction as well as the exothermic CO-hydrogenation in adiabatic reactors and allows the optimization of the district energy circuit under consideration. (orig.) [de

  20. Phase Stability Diagrams for High Temperature Corrosion Processes

    Directory of Open Access Journals (Sweden)

    J. J. Ramos-Hernandez

    2013-01-01

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

  1. Thermodynamic theory of intrinsic finite-size effects in PbTiO3 nanocrystals. I. Nanoparticle size-dependent tetragonal phase stability

    Science.gov (United States)

    Akdogan, E. K.; Safari, A.

    2007-03-01

    We propose a phenomenological intrinsic finite-size effect model for single domain, mechanically free, and surface charge compensated ΔG-P ⃗s-ξ space, which describes the decrease in tetragonal phase stability with decreasing ξ rigorously.

  2. Development of thermodynamic databases for geochemical calculations

    International Nuclear Information System (INIS)

    Arthur, R.C.; Sasamoto, Hiroshi; Shibata, Masahiro; Yui, Mikazu; Neyama, Atsushi

    1999-09-01

    Two thermodynamic databases for geochemical calculations supporting research and development on geological disposal concepts for high level radioactive waste are described in this report. One, SPRONS.JNC, is compatible with thermodynamic relations comprising the SUPCRT model and software, which permits calculation of the standard molal and partial molal thermodynamic properties of minerals, gases, aqueous species and reactions from 1 to 5000 bars and 0 to 1000degC. This database includes standard molal Gibbs free energies and enthalpies of formation, standard molal entropies and volumes, and Maier-Kelly heat capacity coefficients at the reference pressure (1 bar) and temperature (25degC) for 195 minerals and 16 gases. It also includes standard partial molal Gibbs free energies and enthalpies of formation, standard partial molal entropies, and Helgeson, Kirkham and Flowers (HKF) equation-of-state coefficients at the reference pressure and temperature for 1147 inorganic and organic aqueous ions and complexes. SPRONS.JNC extends similar databases described elsewhere by incorporating new and revised data published in the peer-reviewed literature since 1991. The other database, PHREEQE.JNC, is compatible with the PHREEQE series of geochemical modeling codes. It includes equilibrium constants at 25degC and l bar for mineral-dissolution, gas-solubility, aqueous-association and oxidation-reduction reactions. Reaction enthalpies, or coefficients in an empirical log K(T) function, are also included in this database, which permits calculation of equilibrium constants between 0 and 100degC at 1 bar. All equilibrium constants, reaction enthalpies, and log K(T) coefficients in PHREEQE.JNC are calculated using SUPCRT and SPRONS.JNC, which ensures that these two databases are mutually consistent. They are also internally consistent insofar as all the data are compatible with basic thermodynamic definitions and functional relations in the SUPCRT model, and because primary

  3. Development of thermodynamic databases for geochemical calculations

    Energy Technology Data Exchange (ETDEWEB)

    Arthur, R.C. [Monitor Scientific, L.L.C., Denver, Colorado (United States); Sasamoto, Hiroshi; Shibata, Masahiro; Yui, Mikazu [Japan Nuclear Cycle Development Inst., Tokai, Ibaraki (Japan); Neyama, Atsushi [Computer Software Development Corp., Tokyo (Japan)

    1999-09-01

    Two thermodynamic databases for geochemical calculations supporting research and development on geological disposal concepts for high level radioactive waste are described in this report. One, SPRONS.JNC, is compatible with thermodynamic relations comprising the SUPCRT model and software, which permits calculation of the standard molal and partial molal thermodynamic properties of minerals, gases, aqueous species and reactions from 1 to 5000 bars and 0 to 1000degC. This database includes standard molal Gibbs free energies and enthalpies of formation, standard molal entropies and volumes, and Maier-Kelly heat capacity coefficients at the reference pressure (1 bar) and temperature (25degC) for 195 minerals and 16 gases. It also includes standard partial molal Gibbs free energies and enthalpies of formation, standard partial molal entropies, and Helgeson, Kirkham and Flowers (HKF) equation-of-state coefficients at the reference pressure and temperature for 1147 inorganic and organic aqueous ions and complexes. SPRONS.JNC extends similar databases described elsewhere by incorporating new and revised data published in the peer-reviewed literature since 1991. The other database, PHREEQE.JNC, is compatible with the PHREEQE series of geochemical modeling codes. It includes equilibrium constants at 25degC and l bar for mineral-dissolution, gas-solubility, aqueous-association and oxidation-reduction reactions. Reaction enthalpies, or coefficients in an empirical log K(T) function, are also included in this database, which permits calculation of equilibrium constants between 0 and 100degC at 1 bar. All equilibrium constants, reaction enthalpies, and log K(T) coefficients in PHREEQE.JNC are calculated using SUPCRT and SPRONS.JNC, which ensures that these two databases are mutually consistent. They are also internally consistent insofar as all the data are compatible with basic thermodynamic definitions and functional relations in the SUPCRT model, and because primary

  4. The effect of small 4th element alloying additions on the calculated phase stability in the Fe-Cr-Ni system

    International Nuclear Information System (INIS)

    Watkin, J.S.

    1979-01-01

    Recent studies into the void swelling of Fe-Cr-Ni alloys have revealed that the magnitude of swelling depends upon alloy constitution and this together with the fact that minor element additions also play a major role in swelling necessitate a detailed knowledge of the influence of small 4th element additions on phase stability. In this paper the effects of additions of Nb, Ti, Al, Mo, Co and C to the Fe-Cr-Ni ternary are assessed by calculation. They confirm the ferritising tendencies of Nb, Ti and Al and the strong austenitising effect of C. Confirmation is also found for the scaling factors in the equivalent Ni and Cr equations in common usage and the paper presents Fe-Cr-Ni ternary sections at 400, 550 and 700 0 C modified for 1 at.% addition of each of the above elements. (orig.) [de

  5. Investigation of Iron-based double perovskite oxides on the magnetic phase stability, mechanical, electronic and optical properties via first-principles calculation

    Energy Technology Data Exchange (ETDEWEB)

    Rached, H., E-mail: habib_rached@yahoo.fr [Laboratoire des Matériaux Magnétiques, Faculté des Sciences Exactes, Université Djillali Liabès de Sidi Bel-Abbès, Sidi Bel-Abbès, 22000 (Algeria); Département de Physique, Faculté des Sciences Exactes et Informatique, Université Hassiba BenBouali de Chlef, Chlef, 02000 (Algeria); Bendaoudia, S. [Laboratoire des Matériaux Magnétiques, Faculté des Sciences Exactes, Université Djillali Liabès de Sidi Bel-Abbès, Sidi Bel-Abbès, 22000 (Algeria); Rached, D., E-mail: rachdj@yahoo.fr [Laboratoire des Matériaux Magnétiques, Faculté des Sciences Exactes, Université Djillali Liabès de Sidi Bel-Abbès, Sidi Bel-Abbès, 22000 (Algeria)

    2017-06-01

    The main goal of the present work is to obtain report on the magnetic phase stability, mechanical, electronic and optical properties of double perovskite oxides Pb{sub 2}FeMO{sub 6} (M = Mo, Re and W) by employing the ab-initio plane-wave method, based on the density functional theory (DFT). The exchange-correlation (XC) energy of electrons was treated using the Perdew–Burke–Ernzerhof parametrization. The ground-state electronic properties for different magnetic configurations were calculated. The formation enthalpies has been evaluated in order to determinate the stability of our compounds. The independent elastic constants and the related mechanical properties are investigated. The electronic structure calculation reveal the half-metallic ferrimagnets (FiM-HM) for all investigated compounds. The optical constants as the dielectric function, refractive index, optical reflectivity and absorption coefficient were calculated and discussed in detail. Therefore, our compounds are identified as potential candidates for spintronic applications and high performance electronic devices. - Highlights: • Based on the DFT calculation, the Pb{sub 2}FeMO{sub 6} (M = Mo, Re and W) compounds have been investigated. • The ground-state properties are predicted. • The mechanical properties reveals that these compounds are stable against any elastic deformations. • The electronic structures reveals the half-metallic ferrimagnets (FiM-HM) for all investigated compounds.

  6. Entropy and energy quantization: Planck thermodynamic calculation

    International Nuclear Information System (INIS)

    Mota e Albuquerque, Ivone Freire da.

    1988-01-01

    This dissertation analyses the origins and development of the concept of entropy and its meaning of the second Law of thermodynamics, as well as the thermodynamics derivation of the energy quantization. The probabilistic interpretation of that law and its implication in physics theory are evidenciated. Based on Clausius work (which follows Carnot's work), we analyse and expose in a original way the entropy concept. Research upon Boltzmann's work and his probabilistic interpretation of the second Law of thermodynamics is made. The discuss between the atomistic and the energeticist points of view, which were actual at that time are also commented. (author). 38 refs., 3 figs

  7. The calculation of thermodynamic properties of molecules

    DEFF Research Database (Denmark)

    van Speybroeck, Veronique; Gani, Rafiqul; Meier, Robert Johan

    2010-01-01

    Thermodynamic data are key in the understanding and design of chemical processes. Next to the experimental evaluation of such data, computational methods are valuable and sometimes indispensable tools in obtaining heats of formation and Gibbs free energies. The major toolboxes to obtain such quan......Thermodynamic data are key in the understanding and design of chemical processes. Next to the experimental evaluation of such data, computational methods are valuable and sometimes indispensable tools in obtaining heats of formation and Gibbs free energies. The major toolboxes to obtain...... molecules the combination of group contribution methods with group additive values that are determined with the best available computational ab initio methods seems to be a viable alternative to obtain thermodynamic properties near chemical accuracy. New developments and full use of existing tools may lead...

  8. 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

  9. Comments Simplification of thermodynamic calculations through dimensionless entropies

    International Nuclear Information System (INIS)

    Pitzer, K.S.; Brewer, L.

    1979-01-01

    The advantages of using thermodynamic quantities divided by the gas constant (H/R, G/R, etc,) in calculations are described. It is recommended that thermodynamic tables be presented in this form, so that the entries are either dimensionless or in units of kelvins

  10. convergent methods for calculating thermodynamic Green functions

    OpenAIRE

    Bowen, S. P.; Williams, C. D.; Mancini, J. D.

    1984-01-01

    A convergent method of approximating thermodynamic Green functions is outlined briefly. The method constructs a sequence of approximants which converges independently of the strength of the Hamiltonian's coupling constants. Two new concepts associated with the approximants are introduced: the resolving power of the approximation, and conditional creation (annihilation) operators. These ideas are illustrated on an exactly soluble model and a numerical example. A convergent expression for the s...

  11. Methane on Mars: Thermodynamic Equilibrium and Photochemical Calculations

    Science.gov (United States)

    Levine, J. S.; Summers, M. E.; Ewell, M.

    2010-01-01

    The detection of methane (CH4) in the atmosphere of Mars by Mars Express and Earth-based spectroscopy is very surprising, very puzzling, and very intriguing. On Earth, about 90% of atmospheric ozone is produced by living systems. A major question concerning methane on Mars is its origin - biological or geological. Thermodynamic equilibrium calculations indicated that methane cannot be produced by atmospheric chemical/photochemical reactions. Thermodynamic equilibrium calculations for three gases, methane, ammonia (NH3) and nitrous oxide (N2O) in the Earth s atmosphere are summarized in Table 1. The calculations indicate that these three gases should not exist in the Earth s atmosphere. Yet they do, with methane, ammonia and nitrous oxide enhanced 139, 50 and 12 orders of magnitude above their calculated thermodynamic equilibrium concentration due to the impact of life! Thermodynamic equilibrium calculations have been performed for the same three gases in the atmosphere of Mars based on the assumed composition of the Mars atmosphere shown in Table 2. The calculated thermodynamic equilibrium concentrations of the same three gases in the atmosphere of Mars is shown in Table 3. Clearly, based on thermodynamic equilibrium calculations, methane should not be present in the atmosphere of Mars, but it is in concentrations approaching 30 ppbv from three distinct regions on Mars.

  12. Computer program for calculation of ideal gas thermodynamic data

    Science.gov (United States)

    Gordon, S.; Mc Bride, B. J.

    1968-01-01

    Computer program calculates ideal gas thermodynamic properties for any species for which molecular constant data is available. Partial functions and derivatives from formulas based on statistical mechanics are provided by the program which is written in FORTRAN 4 and MAP.

  13. Thermodynamic calculations in ternary titanium–aluminium–manganese system

    Directory of Open Access Journals (Sweden)

    ANA I. KOSTOV

    2008-04-01

    Full Text Available Thermodynamic calculations in the ternary Ti–Al–Mn system are shown in this paper. The thermodynamic calculations were performed using the FactSage thermochemical software and database, with the aim of determining thermodynamic properties, such as activities, coefficient of activities, partial and integral values of the enthalpies and Gibbs energies of mixing and excess energies at two different temperatures: 2000 and 2100 K. Bearing in mind that no experimental data for the Ti–Al–Mn ternary system have been obtained or reported. The obtained results represent a good base for further thermodynamic analysis and may be useful as a comparison with some future critical experimental results and thermodynamic optimization of this system.

  14. Thermodynamic cycle calculations for a pumped gaseous core fission reactor

    International Nuclear Information System (INIS)

    Kuijper, J.C.; Van Dam, H.

    1991-01-01

    Finite and 'infinitesimal' thermodynamic cycle calculations have been performed for a 'solid piston' model of a pumped Gaseous Core Fission Reactor with dissociating reactor gas, consisting of Uranium, Carbon and Fluorine ('UCF'). In the finite cycle calculations the influence has been investigated of several parameters on the thermodynamics of the system, especially on the attainable direct (nuclear to electrical) energy conversion efficiency. In order to facilitate the investigation of the influence of dissociation, a model gas, 'Modelium', was developed, which approximates, in a simplified, analytical way, the dissociation behaviour of the 'real' reactor gas. Comparison of the finite cycle calculation results with those of a so-called infinitesimal Otto cycle calculation leads to the conclusion that the conversion efficiency of a finite cycle can be predicted, without actually performing the finite cycle calculation, with reasonable accuracy, from the so-called 'infinitesimal efficiency factor', which is determined only by the thermodynamic properties of the reactor gas used. (author)

  15. Calculation and analysis of thermodynamic relations for superconductors

    International Nuclear Information System (INIS)

    Nazarenko, A.B.

    1989-01-01

    The absorption coefficients of high-frequency and low-frequency sound have been calculated on the basis of the Ginzburg-Landau theory. This sound is a wave of periodic adiabatic bulk compressions and rarefactions of the frequency ω in an isotropic superconductor near the transition temperature. Thermodynamic relations have been obtained for abrupt changes in the physical quantities produced as a result of a transition from the normal state to the superconducting state. These relations are similar to the Ehrenfest relations. The above--mentioned thermodynamic quantities are compared with the published experimental results on YBa 2 Cu 3 O 7-δ . The experiments on the absorption of ultrasound in recently discovered superconductors mainformation on the phase transition type and thermodynamic relations for these superconductors, in particular, the T c -vs-dp curve. Similar calculations have been carried out for 2 He-transition experiments with ferromagnetic materials. The order parameter in the thermodynamic potential was assumed to be isotropic

  16. THERMODYNAMIC MODELING AND FIRST-PRINCIPLES CALCULATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Turchi, P; Abrikosov, I; Burton, B; Fries, S; Grimvall, G; Kaufman, L; Korzhavyi, P; Manga, R; Ohno, M; Pisch, A; Scott, A; Zhang, W

    2005-12-15

    The increased application of quantum mechanical-based methodologies to the study of alloy stability has required a re-assessment of the field. The focus is mainly on inorganic materials in the solid state. In a first part, after a brief overview of the so-called ab initio methods with their approximations, constraints, and limitations, recommendations are made for a good usage of first-principles codes with a set of qualifiers. Examples are given to illustrate the power and the limitations of ab initio codes. However, despite the ''success'' of these methodologies, thermodynamics of complex multi-component alloys, as used in engineering applications, requires a more versatile approach presently afforded within CALPHAD. Hence, in a second part, the links that presently exist between ab initio methodologies, experiments, and CALPHAD approach are examined with illustrations. Finally, the issues of dynamical instability and of the role of lattice vibrations that still constitute the subject of ample discussions within the CALPHAD community are revisited in the light of the current knowledge with a set of recommendations.

  17. 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)

  18. 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

  19. Modeling precipitation thermodynamics and kinetics in type 316 austenitic stainless steels with varying composition as an initial step toward predicting phase stability during irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Shim, Jae-Hyeok, E-mail: jhshim@kist.re.kr [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996 (United States); High Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Povoden-Karadeniz, Erwin [Christian Doppler Laboratory for Early Stages of Precipitation, Vienna University of Technology, A-1040 Vienna (Austria); Kozeschnik, Ernst [Institute of Materials Science and Technology, Vienna University of Technology, A-1040 Vienna (Austria); Wirth, Brian D. [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996 (United States)

    2015-07-15

    Highlights: • We model the precipitation kinetics in irradiated 316 austenitic stainless steels. • Radiation-induced phases are predicted to form at over 10 dpa segregation conditions. • The Si content is the most critical for the formation of radiation-induced phases. - Abstract: The long-term evolution of precipitates in type 316 austenitic stainless steels at 400 °C has been simulated using a numerical model based on classical nucleation theory and the thermodynamic extremum principle. Particular attention has been paid to the precipitation of radiation-induced phases such as γ′ and G phases. In addition to the original compositions, the compositions for radiation-induced segregation at a dose level of 5, 10 or 20 dpa have been used in the simulation. In a 316 austenitic stainless steel, γ′ appears as the main precipitate with a small amount of G phase forming at 10 and 20 dpa. On the other hand, G phase becomes relatively dominant over γ′ at the same dose levels in a Ti-stabilized 316 austenitic stainless steel, which tends to suppress the formation of γ′. Among the segregated alloying elements, the concentration of Si seems to be the most critical for the formation of radiation-induced phases. An increase in dislocation density as well as increased diffusivity of Mn and Si significantly enhances the precipitation kinetics of the radiation-induced phases within this model.

  20. Calculation of thermodynamic properties of finite Bose-Einstein systems

    NARCIS (Netherlands)

    Borrmann, P.; Harting, J.D.R.; Mülken, O.; Hilf, E.

    1999-01-01

    We derive an exact recursion formula for the calculation of thermodynamic functions of finite systems obeying Bose-Einstein statistics. The formula is applicable for canonical systems where the particles can be treated as noninteracting in some approximation, e.g., like Bose-Einstein condensates in

  1. Microcomputer Calculation of Thermodynamic Properties from Molecular Parameters of Gases.

    Science.gov (United States)

    Venugopalan, Mundiyath

    1990-01-01

    Described in this article is a problem-solving activity which integrates the application of microcomputers with the learning of physical chemistry. Students use the program with spectroscopic data to calculate the thermodynamic properties and compare them with the values from the thermochemical tables. (Author/KR)

  2. Thermodynamic calculation of the Fe-Zn-Si system

    Energy Technology Data Exchange (ETDEWEB)

    Su Xuping [Institute of Materials Research, School of Mechanical Engineering, Xiangtan University, Xiangtan 411105, Hunan (China)]. E-mail: sxping@xtu.edu.cn; Yin Fucheng [Institute of Materials Research, School of Mechanical Engineering, Xiangtan University, Xiangtan 411105, Hunan (China); Li Zhi [Institute of Materials Research, School of Mechanical Engineering, Xiangtan University, Xiangtan 411105, Hunan (China); Tang, N.-Y. [Teck Cominco Metals Ltd., Product Technology Centre, Mississauga, Ont., L5K 1B4 (Canada); Zhao Manxiu [Institute of Materials Research, School of Mechanical Engineering, Xiangtan University, Xiangtan 411105, Hunan (China)

    2005-06-21

    Silicon in steel significantly affects alloy growth kinetics in the coating in general galvanizing, thereby changing the coating microstructure from the usual stratified Fe-Zn alloy layers to a mass of {zeta} crystallites surrounding by liquid zinc. The Zn-Fe-Si phase diagram and the relevant thermodynamic information have great importance for the galvanizing industry in developing remedies for this problem. In this work, the available information on the Fe-Zn-Si system, including all three binary systems was reviewed and re-evaluated, and ternary parameters were extracted from the available experimental data. By assuming all the binary intermetallic phases with the exception of the {delta}, {gamma}{sub 1}, and {gamma} phases, have no ternary solubility, a thermodynamic calculation of the Fe-Zn-Si system was carried out, and relevant isothermal and isopleths sections were calculated. Its applicability in galvanizing industry was discussed. There is a good agreement between the calculated and the experimentally determined phase boundaries.

  3. The statistic-thermodynamically calculations of magnetic thermodynamically functions for nuclear magnetic moments

    International Nuclear Information System (INIS)

    Zhu Zhenghe; Luo Deli; Feng Kaiming

    2013-01-01

    The present work is to calculate the magnetic thermodynamically functions, i.e. energy, the intensity of magnetization, enthalpy, entropy and Gibbs function for nuclear magnetic moments of T, D and neutron n at 2 T and 1, 50, 100 and 150 K from partition functions. It is shown that magnetic saturation of thermonuclear plasma does not easily occur for nuclear magneton is only of 10 -3 of Bohr magneton. The work done by magnetic field is considerable. (authors)

  4. Martensitic transformation and phase stability of In-doped Ni-Mn-Sn shape memory alloys from first-principles calculations

    International Nuclear Information System (INIS)

    Xiao, H. B.; Yang, C. P.; Wang, R. L.; Luo, X.; Marchenkov, V. V.

    2014-01-01

    The effect of the alloying element Indium (In) on the martensitic transition, magnetic properties, and phase stabilities of Ni 8 Mn 6 Sn 2−x In x shape memory alloys has been investigated using the first-principles pseudopotential plane-wave method based on density functional theory. The energy difference between the austenitic and martensitic phases was found to increase with increasing In content, which implies an enhancement of the martensitic phase transition temperature (T M ). Moreover, the formation energy results indicate that In-doping increases the relative stability of Ni 8 Mn 6 Sn 2−x In x both in austenite and martensite. This results from a reduction in density of states near the Fermi level regions caused by Ni-3d–In-5p hybridization when Sn is replaced by In. The equilibrium equation of state results show that the alloys Ni 8 Mn 6 Sn 2−x In x exhibit an energetically degenerated effect for an In content of x = ∼1.5. This implies the coexistence of antiparallel and parallel configurations in the austenite.

  5. SOLGAS refined: A computerized thermodynamic equilibrium calculation tool

    Energy Technology Data Exchange (ETDEWEB)

    Trowbridge, L.D.; Leitnaker, J.M.

    1993-11-01

    SOLGAS, an early computer program for calculating equilibrium in a chemical system, has been made more user-friendly, and several{open_quote} bells and whistles{close_quotes} have been added. The necessity to include elemental species has been eliminated. The input of large numbers of starting conditions has been automated. A revised format for entering data simplifies and reduces chances for error. Calculated errors by SOLGAS are flagged, and several programming errors are corrected. Auxiliary programs are available to assemble and partially automate plotting of large amounts of data. Thermodynamic input data can be changed {open_quotes}on line.{close_quote} The program can be operated with or without a co-processor. Copies of the program, suitable for the IBM-PC or compatible with at least 384 bytes of low RAM, are available from the authors.

  6. SOLGAS refined: A computerized thermodynamic equilibrium calculation tool

    International Nuclear Information System (INIS)

    Trowbridge, L.D.; Leitnaker, J.M.

    1993-11-01

    SOLGAS, an early computer program for calculating equilibrium in a chemical system, has been made more user-friendly, and several open-quote bells and whistlesclose quotes have been added. The necessity to include elemental species has been eliminated. The input of large numbers of starting conditions has been automated. A revised format for entering data simplifies and reduces chances for error. Calculated errors by SOLGAS are flagged, and several programming errors are corrected. Auxiliary programs are available to assemble and partially automate plotting of large amounts of data. Thermodynamic input data can be changed open-quotes on line.close-quote The program can be operated with or without a co-processor. Copies of the program, suitable for the IBM-PC or compatible with at least 384 bytes of low RAM, are available from the authors

  7. A New Thermodynamic Calculation Method for Binary Alloys: Part I: Statistical Calculation of Excess Functions

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The improved form of calculation formula for the activities of the components in binary liquids and solid alloys has been derived based on the free volume theory considering excess entropy and Miedema's model for calculating the formation heat of binary alloys. A calculation method of excess thermodynamic functions for binary alloys, the formulas of integral molar excess properties and partial molar excess properties for solid ordered or disordered binary alloys have been developed. The calculated results are in good agreement with the experimental values.

  8. Thermodynamic Equilibrium Calculations on Cd Transformation during Sewage Sludge Incineration.

    Science.gov (United States)

    Liu, Jing-yong; Huang, Limao; Sun, Shuiyu; Ning, Xun'an; Kuo, Jiahong; Sun, Jian; Wang, Yujie; Xie, Wuming

    2016-06-01

    Thermodynamic equilibrium calculations were performed to reveal the distribution of cadmium during the sewage sludge incineration process. During sludge incineration in the presence of major minerals, such as SiO2, Al2O3 and CaO, the strongest effect was exerted by SiO2 on the Cd transformation compared with the effect of others. The stable solid product of CdSiO3 was formed easily with the reaction between Cd and SiO2, which can restrain the emissions of gaseous Cd pollutants. CdCl2 was formed more easily in the presence of chloride during incineration, thus, the volatilization of Cd was advanced by increasing chlorine content. At low temperatures, the volatilization of Cd was restrained due to the formation of the refractory solid metal sulfate. At high temperatures, the speciation of Cd was not affected by the presence of sulfur, but sulfur could affect the formation temperature of gaseous metals.

  9. 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

  10. Electronic structure theory of alloy phase stability

    International Nuclear Information System (INIS)

    Turchi, P.E.A.; Sluiter, M.

    1992-01-01

    We present a brief overview of the advanced methodology which has been developed and applied to the study of phase stability properties in substitutional alloys. The approach is based on the real space version of the Generalized Perturbation Method within the Korringa-Kohn-Rostoker multiple scattering formulation of the Coherent Potential Approximation. Temperature effects are taken into account with a generalized meanfield approach, namely the Cluster Variation Method, or with Monte-Carlo simulations. We show that this approach is well suited for studying ground state properties of substitutional alloys, for calculating energies of idealized interfaces and antiphase boundaries, and finally to compute alloy phase diagrams

  11. Computer codes used in the calculation of high-temperature thermodynamic properties of sodium

    International Nuclear Information System (INIS)

    Fink, J.K.

    1979-12-01

    Three computer codes - SODIPROP, NAVAPOR, and NASUPER - were written in order to calculate a self-consistent set of thermodynamic properties for saturated, subcooled, and superheated sodium. These calculations incorporate new critical parameters (temperature, pressure, and density) and recently derived single equations for enthalpy and vapor pressure. The following thermodynamic properties have been calculated in these codes: enthalpy, heat capacity, entropy, vapor pressure, heat of vaporization, density, volumetric thermal expansion coefficient, compressibility, and thermal pressure coefficient. In the code SODIPROP, these properties are calculated for saturated and subcooled liquid sodium. Thermodynamic properties of saturated sodium vapor are calculated in the code NAVAPOR. The code NASUPER calculates thermodynamic properties for super-heated sodium vapor only for low (< 1644 K) temperatures. No calculations were made for the supercritical region

  12. Thermodynamic modeling of the Sc-Zn system coupled with first-principles calculation

    Directory of Open Access Journals (Sweden)

    Tang C.

    2012-01-01

    Full Text Available The Sc-Zn system has been critically reviewed and assessed by means of CALPHAD (CALculation of PHAse Diagram approach. By means of first-principles calculation, the enthalpies of formation at 0 K for the ScZn, ScZn2, Sc17Zn58, Sc3Zn17 and ScZn12 have been computed with the desire to assist thermodynamic modeling. A set of self-consistent thermodynamic parameters for the Sc-Zn system is then obtained. The calculated phase diagram and thermodynamic properties agree well with the experimental data and first-principles calculations, respectively.

  13. Numerical Simulation of Shale Gas Production with Thermodynamic Calculations Incorporated

    KAUST Repository

    Urozayev, Dias

    2015-06-01

    In today’s energy sector, it has been observed a revolutionary increase in shale gas recovery induced by reservoir fracking. So-called unconventional reservoirs became profitable after introducing a well stimulation technique. Some of the analysts expect that shale gas is going to expand worldwide energy supply. However, there is still a lack of an efficient as well as accurate modeling techniques, which can provide a good recovery and production estimates. Gas transports in shale reservoir is a complex process, consisting of slippage effect, gas diffusion along the wall, viscous flow due to the pressure gradient. Conventional industrial simulators are unable to model the flow as the flow doesn’t follow Darcy’s formulation. It is significant to build a unified model considering all given mechanisms for shale reservoir production study and analyze the importance of each mechanism in varied conditions. In this work, a unified mathematical model is proposed for shale gas reservoirs. The proposed model was build based on the dual porosity continuum media model; mass conservation equations for both matrix and fracture systems were build using the dusty gas model. In the matrix, gas desorption, Knudsen diffusion and viscous flow were taken into account. The model was also developed by implementing thermodynamic calculations to correct for the gas compressibility, or to obtain accurate treatment of the multicomponent gas. Previously, the model was built on the idealization of the gas, considering every molecule identical without any interaction. Moreover, the compositional variety of shale gas requires to consider impurities in the gas due to very high variety. Peng-Robinson equation of state was used to com- pute and correct for the gas density to pressure relation by solving the cubic equation to improve the model. The results show that considering the compressibility of the gas will noticeably increase gas production under given reservoir conditions and slow down

  14. Computer program for calculating thermodynamic and transport properties of fluids

    Science.gov (United States)

    Hendricks, R. C.; Braon, A. K.; Peller, I. C.

    1975-01-01

    Computer code has been developed to provide thermodynamic and transport properties of liquid argon, carbon dioxide, carbon monoxide, fluorine, helium, methane, neon, nitrogen, oxygen, and parahydrogen. Equation of state and transport coefficients are updated and other fluids added as new material becomes available.

  15. Calculation of the thermodynamic properties of liquid Ag–In–Sb alloys

    Directory of Open Access Journals (Sweden)

    DRAGANA ZIVKOVIC

    2006-03-01

    Full Text Available The results of calculations of the thermodynamic properties of liquid Ag–In–Sb alloys are presented in this paper. The Redlich–Kister–Muggianu model was used for the calculations. Based on known thermodynamic data for constitutive binary systems and available experimental data for the investigated ternary system, the ternary interaction parameter for the liquid phase in the temperature range 1000–1200 K was determined. Comparison between experimental and calculated results showed their good mutual agreement.

  16. Phase stability in yttria-stabilized zirconia from first principles

    Energy Technology Data Exchange (ETDEWEB)

    Carbogno, Christian; Scheffler, Matthias [Materials Department, University of California, Santa Barbara, CA (United States); Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin (Germany); Levi, Carlos G.; Van de Walle, Chris G. [Materials Department, University of California, Santa Barbara, CA (United States)

    2012-07-01

    Zirconia based ceramics are of pivotal importance for a variety of industrial technologies, e.g., for thermal barrier coatings in gas and airplane turbines. Naturally, the stability of such coatings at elevated temperatures plays a critical role in these applications. It is well known that an aliovalent doping of tetragonal ZrO{sub 2} with yttria, which induces oxygen vacancies due to charge conservation, increases its thermodynamic stability. However, the atomistic mechanisms that determine the phase stability of such yttria-stabilized Zirconia (YSZ) coatings are not yet fully understood. In this work, we use density functional theory calculations to assess the electronic structure of the different YSZ polymorphs at various levels of doping. With the help of population analysis schemes, we are able to unravel the intrinsic mechanisms that govern the interaction in YSZ and that can so explain the relative stabilities of the various polymorphs. We critically compare our results to experimental measurements and discuss the implications of our findings with respect to other oxides.

  17. Integrated design of Nb-based superalloys: Ab initio calculations, computational thermodynamics and kinetics, and experimental results

    International Nuclear Information System (INIS)

    Ghosh, G.; Olson, G.B.

    2007-01-01

    An optimal integration of modern computational tools and efficient experimentation is presented for the accelerated design of Nb-based superalloys. Integrated within a systems engineering framework, we have used ab initio methods along with alloy theory tools to predict phase stability of solid solutions and intermetallics to accelerate assessment of thermodynamic and kinetic databases enabling comprehensive predictive design of multicomponent multiphase microstructures as dynamic systems. Such an approach is also applicable for the accelerated design and development of other high performance materials. Based on established principles underlying Ni-based superalloys, the central microstructural concept is a precipitation strengthened system in which coherent cubic aluminide phase(s) provide both creep strengthening and a source of Al for Al 2 O 3 passivation enabled by a Nb-based alloy matrix with required ductile-to-brittle transition temperature, atomic transport kinetics and oxygen solubility behaviors. Ultrasoft and PAW pseudopotentials, as implemented in VASP, are used to calculate total energy, density of states and bonding charge densities of aluminides with B2 and L2 1 structures relevant to this research. Characterization of prototype alloys by transmission and analytical electron microscopy demonstrates the precipitation of B2 or L2 1 aluminide in a (Nb) matrix. Employing Thermo-Calc and DICTRA software systems, thermodynamic and kinetic databases are developed for substitutional alloying elements and interstitial oxygen to enhance the diffusivity ratio of Al to O for promotion of Al 2 O 3 passivation. However, the oxidation study of a Nb-Hf-Al alloy, with enhanced solubility of Al in (Nb) than in binary Nb-Al alloys, at 1300 deg. C shows the presence of a mixed oxide layer of NbAlO 4 and HfO 2 exhibiting parabolic growth

  18. For effective thermodynamic calculation of turbines flow-through by gas and steam

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, S; Hultsch, M

    1982-03-01

    A programme system for the medium and multiple section calculation of axial-flow turbines is explained. It allows calculations of turbine flow-through by gas and steam at designing and partial load states. The algorithms are independent upon the formulation of thermodynamic function, so that the programmes can be used for any means of production. The highest accuracy and efficiency can be guaranteed by the use of formulations of thermodynamic functions of water.

  19. Thermodynamic Calculation of Carbide Precipitate in Niobium Microalloyed Steels

    Institute of Scientific and Technical Information of China (English)

    XU Yun-bo; YU Yong-mei; LIU Xiang-hua; WANG Guo-dong

    2006-01-01

    On the basis of regular solution sublattice model, thermodynamic equilibrium of austenite/carbide in Fe-Nb-C ternary system was investigated. The equilibrium volume fraction, chemical driving force of carbide precipitates and molar fraction of niobium and carbon in solution at different temperatures were evaluated respectively. The volume fraction of precipitates increases, molar fraction of niobium dissolved in austenite decreases and molar fraction of carbon increases with decreasing the niobium content. The driving force increases with the decrease of temperature, and then comes to be stable at relatively low temperatures. The predicted ratio of carbon in precipitates is in good agreement with the measured one.

  20. Calculation of thermodynamic properties of multicomponent ionic reciprocal systems

    International Nuclear Information System (INIS)

    Saboungi, M.

    1980-01-01

    Thermodynamic properties of multicomponent ionic reciprocal systems are derived using the conformal ionic solution theory. The equations obtained are more general than previous equations and depend solely on the properties of the components and on those of the binary subsystems. The behavior of dilute solutions is carefully studied leading to a priori predictions of solubility products in multicomponent systems. The solubility products and the specific bond free energy for making an ion pair, e.g., the pair (A--X) in the binary solvent BY--CY, are shown to depend upon specific ionic interactions in the binary subsystems. The equations presented are compared with equations derived from prior theories

  1. Monte Carlo simulations for thermodynamical properties calculations of plasmas at thermodynamical equilibrium. Applications to opacity and equation of state calculations

    International Nuclear Information System (INIS)

    Gilles, D.

    2005-01-01

    This report is devoted to illustrate the power of a Monte Carlo (MC) simulation code to study the thermodynamical properties of a plasma, composed of classical point particles at thermodynamical equilibrium. Such simulations can help us to manage successfully the challenge of taking into account 'exactly' all classical correlations between particles due to density effects, unlike analytical or semi-analytical approaches, often restricted to low dense plasmas. MC simulations results allow to cover, for laser or astrophysical applications, a wide range of thermodynamical conditions from more dense (and correlated) to less dense ones (where potentials are long ranged type). Therefore Yukawa potentials, with a Thomas-Fermi temperature- and density-dependent screening length, are used to describe the effective ion-ion potentials. In this report we present two MC codes ('PDE' and 'PUCE') and applications performed with these codes in different fields (spectroscopy, opacity, equation of state). Some examples of them are discussed and illustrated at the end of the report. (author)

  2. Experimental investigation and thermodynamic calculation of the Mg-Sr-Zr system

    International Nuclear Information System (INIS)

    Zhou, Hua; Chen, Chong; Du, Yong; Central South Univ., Hunan; Gong, Haoran

    2016-01-01

    Both experimental investigation and thermodynamic calculation were performed for the Mg-Sr-Zr system. Four decisive alloys were firstly selected and prepared using a powder metallurgy method to measure the isothermal section at 400 C via a combination of X-ray diffraction and electron probe microanalysis. No ternary compound has been observed for this ternary system. Four three-phase regions, (Mg) + (αZr) + Mg 17 Sr 2 , Mg 17 Sr 2 + (αZr) + Mg 38 Sr 9 , Mg 38 Sr 9 + (αZr) + Mg 23 Sr 6 , and Mg 23 Sr 6 + (αZr) + Mg 2 Sr, have been identified at 400 C. No appreciable ternary solubility has been detected in the binary Mg-Sr compounds. Phase transition temperatures of the Mg-Sr-Zr alloys were measured by means of differential scanning calorimetry. The thermodynamic calculations match well with the experimental data in the present work, indicating that no ternary thermodynamic parameters are needed for the thermodynamic description of this ternary system. In order to verify the reliability of the current thermodynamic calculations of the Mg-Sr-Zr system, eight as-cast alloys in the Mg-rich corner were also prepared. The calculated liquidus projection is consistent with the observed primary phase regions. The present thermodynamic calculations are reliable and can be used in the development of Mg alloys.

  3. Thermodynamic assessment of the Sn–Sr system supported by first-principles calculations

    International Nuclear Information System (INIS)

    Zhao, Jingrui; Du, Yong; Zhang, Lijun; Wang, Aijun; Zhou, Liangcai; Zhao, Dongdong; Liang, Jianlie

    2012-01-01

    Highlights: ► All the literature data of Sn–Sr system is critically reviewed. ► First-principles calculation of enthalpy of formation is carried out for each compound. ► Thermodynamic parameters for Sn–Sr system are obtained by CALPHAD method. ► A hybrid approach of CALPHAD and first-principles calculations is recommended. - Abstract: A hybrid approach of CALPHAD and first-principles calculations was employed to perform a thermodynamic modeling of the Sn–Sr system. The experimental phase diagram and thermodynamic data available in the literature were critically reviewed. The enthalpies of formation for the 6 stoichiometric compounds (i.e. Sr 2 Sn, Sr 5 Sn 3 , SrSn, Sr 3 Sn 5 , SrSn 3 and SrSn 4 ) at 0 K were computed by means of first-principles calculations. These data were used as the experimental values in the optimization module PARROT in the subsequent CALPHAD assessment to provide thermodynamic parameters with sound physical meaning. A set of self-consistent thermodynamic parameters was finally obtained by considering reliable literature data and the first-principles computed results. Comprehensive comparisons between the calculated and measured quantities indicate that all the reliable experimental information can be satisfactorily accounted for by the present thermodynamic description.

  4. 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

  5. Calculation of parameter failure probability of thermodynamic system by response surface and importance sampling method

    International Nuclear Information System (INIS)

    Shang Yanlong; Cai Qi; Chen Lisheng; Zhang Yangwei

    2012-01-01

    In this paper, the combined method of response surface and importance sampling was applied for calculation of parameter failure probability of the thermodynamic system. The mathematics model was present for the parameter failure of physics process in the thermodynamic system, by which the combination arithmetic model of response surface and importance sampling was established, then the performance degradation model of the components and the simulation process of parameter failure in the physics process of thermodynamic system were also present. The parameter failure probability of the purification water system in nuclear reactor was obtained by the combination method. The results show that the combination method is an effective method for the calculation of the parameter failure probability of the thermodynamic system with high dimensionality and non-linear characteristics, because of the satisfactory precision with less computing time than the direct sampling method and the drawbacks of response surface method. (authors)

  6. 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.)

  7. Alloy phase stability and design

    International Nuclear Information System (INIS)

    Stocks, G.M.; Pope, E.P.; Giamei, A.F.

    1991-01-01

    At the level of basic quantum theory the papers in this symposium reflect the great progress that has been made in understanding the physical properties of both ordered and disordered alloys based on Density Functional Theory (DFT). DFT provides a quantitative parameter-free (often referred to as first principles) theory of the ground state properties of these systems. This general approach has also been used in combination with classical elasticity and dislocation theory to provide the first quantitative understanding of some of the mechanical properties of intermetallic alloys. Recent advances have built on DFT theory to provide the first glimpses of a theory of the finite temperature phase stability of alloys. It is the strength of these first principles theories that the understanding of materials properties is in terms of the underlying electronic structure. At the level of atomistic simulation, based on semi-empirical potentials, again much progress has been made in understanding the properties of extended defects such as grain boundaries and dislocations. On the experimental front increasingly sophisticated tools are being brought to bear in order to understand both the underlying electronic structure and detailed atomic arrangements. This information, together with input from theory, is playing an increasing role in guiding alloy design efforts. At the more practical level a number of these sophisticated alloy design efforts have in recent years produced impressive results across a broad front. The properties of existing materials are continually being improved and new ones developed. Often this progress is based on a deeper understanding of the properties at the atomistic and electronic level. The design of new ordered intermetallic alloys that have reached or are reaching commercialization represents one of the major achievements of this investment of intellectual resources

  8. Structural characterization of Am(III) formate complexes. Combining EXAFS spectroscopy with DFT and thermodynamical calculations

    Energy Technology Data Exchange (ETDEWEB)

    Rossberg, Andre [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Molecular Structures; Froehlich, D.R. [Heidelberg Univ. (Germany). Physikalisch-Chemisches Inst.

    2017-06-01

    We used iterative transformation factor analysis (ITFA) in order to isolate the EXAFS spectral contributions of the complexing ligand from a Am(III)/formate pH-series. Thermodynamic calculations were used as constraint for ITFA and for density functional theory (DFT) calculations to identify the coordination mode within the formed complexes.

  9. Calculations of proton-binding thermodynamics in proteins.

    Science.gov (United States)

    Beroza, P; Case, D A

    1998-01-01

    Computational models of proton binding can range from the chemically complex and statistically simple (as in the quantum calculations) to the chemically simple and statistically complex. Much progress has been made in the multiple-site titration problem. Calculations have improved with the inclusion of more flexibility in regard to both the geometry of the proton binding and the larger scale protein motions associated with titration. This article concentrated on the principles of current calculations, but did not attempt to survey their quantitative performance. This is (1) because such comparisons are given in the cited papers and (2) because continued developments in understanding conformational flexibility and interaction energies will be needed to develop robust methods with strong predictive power. Nevertheless, the advances achieved over the past few years should not be underestimated: serious calculations of protonation behavior and its coupling to conformational change can now be confidently pursued against a backdrop of increasing understanding of the strengths and limitations of such models. It is hoped that such theoretical advances will also spur renewed experimental interest in measuring both overall titration curves and individual pKa values or pKa shifts. Exploration of the shapes of individual titration curves (as measured by Hill coefficients and other parameters) would also be useful in assessing the accuracy of computations and in drawing connections to functional behavior.

  10. Thermodynamic calculations for chemical vapor deposition of silicon carbide

    International Nuclear Information System (INIS)

    Minato, Kazuo; Fukuda, Kousaku; Ikawa, Katsuichi

    1985-03-01

    The composition of vapor and condensed phases at equilibrium and CVD phase diagrams were calculated for the CH 3 SiCl 3 -H 2 -Ar system using a computer code SOLGASMIX-PV, which is based on the free energy minimization method. These calculations showed that β-SiC, β-SiC+C(s), β-SiC+Si(s), β-SiC+Si(l), Si(s), Si(l), or C(s) would be deposited depending on deposition parameters. In the CH 3 SiCl 3 -Ar system, condensed phase was found to be β-SiC+C(s) or C(s). Comparing the calculated CVD phase diagrams with the experimental results from the literature, β-SiC+C(s) and β-SiC+Si(s) were deposited in the experiments at the high temperature (more than 2000K) and low temperature (less than 1700K) parts of a resion, respectively, where only β-SiC would be deposited in the calculations. These are remakable results to consider the deposition mechanism of silicon carbide. (author)

  11. Thermodynamics of Rh nuclear spins calculated by exact diagonalization

    DEFF Research Database (Denmark)

    Lefmann, K.; Ipsen, J.; Rasmussen, F.B.

    2000-01-01

    We have employed the method of exact diagonalization to obtain the full-energy spectrum of a cluster of 16 Rh nuclear spins, having dipolar and RK interactions between first and second nearest neighbours only. We have used this to calculate the nuclear spin entropy, and our results at both positi...

  12. Thermodynamic properties of titanium from ab initio calculations

    International Nuclear Information System (INIS)

    Argaman, Uri; Makov, Guy; Eidelstein, Eitan; Levy, Ohad

    2015-01-01

    The lattice parameters, lattice stability and phonon dispersion curves of five proposed phases of Ti: α, β, γ, δ and ω are investigated within density functional theory (DFT). It is found that the sequence of high pressure phases at zero temperature is α→ω→γ→δ→β with the δ and β phases becoming degenerate at high pressure. However, the γ phase may be unstable as is reflected by the existence of imaginary values in the phonon spectra. The results of the DFT calculations are employed to estimate the entropy and free energies of the α and ω phases. It is found that converged phonon calculations lead to an entropy difference which is much smaller than previous estimates, and a much steeper α−ω phase transition line. (paper)

  13. Calculation of thermodynamic equilibrium for reactions of plutonium with air

    International Nuclear Information System (INIS)

    Zou Lexi; Sun Ying; Luo Deli; Xue Weidong; Zhu Zhenghe; Wang Rong

    2000-01-01

    There are six independent component with 4 chemical elements, i.e. PuH 2.7 (s), PuN(s), Pu 2 O 3 (s), N 2 (g) and H 2 (g), therefore, the system described involves of 2 independent reactions, both ΔG degree << O. The mass balances calculated for gas and solid phases are in good agreement with those of experimental, indicating the chemical equilibrium is nearly approached. So, it is believed that the reaction ratio of plutonium hydride with air is extremely rapid. The results are meaningful to the storage of plutonium

  14. Investigation of phase stability in the scandia-zirconia

    International Nuclear Information System (INIS)

    Grosso, Robson Lopes

    2016-01-01

    In this work, the phase stability of scandia-zirconia (ScSZ) system was investigated by the thermodynamic study of nanoparticles, within the range of 0 to 20 mol% Sc 2 O 3 , and by codoping of ZrO 2 -10 mol% Sc 2 O 3 (10ScSZ) with Dy 2 O 3 and Nb 2 O 5 . The phase stability of ScSZ was evaluated based on thermodynamic data collected by water adsorption microcalorimetry and high temperature oxide melt solution. Nanostructured zirconia-scandia solid solutions were synthesized by coprecipitation method. Thermodynamic data were determined for ScSZ polymorph (monoclinic, tetragonal, cubic, rhombohedral β and γ) found by X-ray diffraction. This systemic work resulted in an unprecedented phase diagram at the nanoscale of particle size-composition. The effects of additives on 10ScSZ were investigated aiming to stabilize the cubic (c) structure at room temperature and to suppress the characteristic cubic-rhombohedral β phase transformation. Compositions were prepared by coprecipitation and solid state reaction. Materials were sintered by conventional and spark plasma sintering. Full stabilization of the cubic phase was attained by 1 mol% Dy 2 O 3 and 0.5 mol% Nb 2 O 5 additions. The smallest Nb 2 O 5 content required for cubic phase stabilization was attributed to liquid phase formation during sintering and to small ionic radius of Nb 5+ . Results of high temperature X-ray diffraction and thermal analysis show suppression of the c-β transformation. Samples containing 0.5 mol% Nb 2 O 5 show total ionic conductivity similar to 10ScSZ without additives within a broad temperature range with high stability during 170 h at 600 °C. (author)

  15. Effective interactions approach to phase stability in alloys under irradiation

    International Nuclear Information System (INIS)

    Enrique, R.A.; Bellon, P.

    1999-01-01

    Phase stability in alloys under irradiation is studied considering effective thermodynamic potentials. A simple kinetic model of a binary alloy with phase separation is investigated. Time evolution in the alloy results from two competing dynamics: thermal diffusion, and irradiation induced ballistic exchanges The dynamical (steady state) phase diagram is evaluated exactly performing Kinetic Monte Carlo simulations. The solution is then compared to two theoretical frameworks: the effective quasi-interactions model as proposed by Vaks and Kamishenko, and the effective free energy model as proposed by Martin. New developments of these models are proposed to allow for quantitative comparisons. Both theoretical frameworks yield fairly good approximations to the dynamical phase diagram

  16. Effective interactions approach to phase stability in alloys under irradiation

    International Nuclear Information System (INIS)

    Enrique, R.A.; Bellon, P.

    1999-01-01

    Phase stability in alloys under irradiation is studied considering effective thermodynamic potentials. A simple kinetic model of a binary alloy with phase separation is investigated. Time evolution in the alloy results form two competing dynamics: thermal diffusion, and irradiation induced ballistic exchanges. The dynamical (steady state) phase diagram is evaluated exactly performing Kinetic Monte Carlo simulations. The solution is then compared to two theoretical frameworks: the effective quasi-interactions model as proposed by Vaks and Kamishenko, and the effective free energy model as proposed by Martin. New developments of these models are proposed to allow for quantitative comparisons. Both theoretical frameworks yield fairly good approximations to the dynamical phase diagram

  17. Prediction of ash deposition using CFD simulation combined to thermodynamic calculation

    Energy Technology Data Exchange (ETDEWEB)

    Takeshi Muratani; Takashi Hongo [UBE Industries, Ltd., Yamaguchi (Japan). Coal Department, Energy and Environment Division

    2007-07-01

    This study focused on the advanced ash deposition prediction using computational fluid dynamics (CFD) analysis combined to thermodynamic calculation, considering both combustion characteristics and ash fusibility. Combustion field in pulverised coal-fired boiler was calculated through the normal CFD process. As the post process of combustion calculation, ash particles were injected into the combustion field to calculate ash deposition by CFD, in which particle sticking sub-program was newly employed. In this post process, ash deposition condition for CFD calculation was defined with the ash fusibility data obtained from thermodynamic analysis. These results of ash deposition on the furnace wall showed good agreement with the plant observation. Furthermore, in order to improve the plant operation, some virtual cases were simulated, which might reduce ash deposition. 7 refs., 14 figs., 6 tabs.

  18. Thermodynamics

    CERN Document Server

    Fermi, Enrico

    1956-01-01

    Indisputably, this is a modern classic of science. Based on a course of lectures delivered by the author at Columbia University, the text is elementary in treatment and remarkable for its clarity and organization. Although it is assumed that the reader is familiar with the fundamental facts of thermometry and calorimetry, no advanced mathematics beyond calculus is assumed.Partial contents: thermodynamic systems, the first law of thermodynamics (application, adiabatic transformations), the second law of thermodynamics (Carnot cycle, absolute thermodynamic temperature, thermal engines), the entr

  19. 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.

  20. Thermodynamic Integration Methods, Infinite Swapping and the Calculation of Generalized Averages

    OpenAIRE

    Doll, J. D.; Dupuis, P.; Nyquist, P.

    2016-01-01

    In the present paper we examine the risk-sensitive and sampling issues associated with the problem of calculating generalized averages. By combining thermodynamic integration and Stationary Phase Monte Carlo techniques, we develop an approach for such problems and explore its utility for a prototypical class of applications.

  1. Electrochemical dissolution of surface alloys in acids: Thermodynamic trends from first-principles calculations

    DEFF Research Database (Denmark)

    Greeley, Jeffrey Philip; Nørskov, Jens Kehlet

    2007-01-01

    A simple procedure is introduced to use periodic Density Functional Theory calculations to estimate trends in the thermodynamics of surface alloy dissolution in acidic media. With this approach, the dissolution potentials for solute metal atoms embedded in the surface layer of various host metals...

  2. Structural, Mechanical and Thermodynamic Properties under Pressure Effect of Rubidium Telluride: First Principle Calculations

    Directory of Open Access Journals (Sweden)

    Bidai K.

    2017-06-01

    Full Text Available First-principles density functional theory calculations have been performed to investigate the structural, elastic and thermodynamic properties of rubidium telluride in cubic anti-fluorite (anti-CaF2-type structure. The calculated ground-state properties of Rb2Te compound such as equilibrium lattice parameter and bulk moduli are investigated by generalized gradient approximation (GGA-PBE that are based on the optimization of total energy. The elastic constants, Young’s and shear modulus, Poisson ratio, have also been calculated. Our results are in reasonable agreement with the available theoretical and experimental data. The pressure dependence of elastic constant and thermodynamic quantities under high pressure are also calculated and discussed.

  3. 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.

  4. 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.

  5. Glass formation of the Fe-Hf system studied by thermodynamic calculation and ion beam mixing

    International Nuclear Information System (INIS)

    Wang, T.L.; Wang, W.C.; Li, J.H.; Liu, B.X.

    2010-01-01

    For the Fe-Hf system characterized by a negative heat of formation, the glass-forming range/ability (GFR/GFA) was studied by thermodynamic calculation based on Miedema's model and Alonso's method. It was found that amorphous phase could be formed in a composition range of 24-86 atom% Hf and that alloy with composition of Fe 58 Hf 42 has the best GFA in the system. Experimentally, ion beam mixing was carried out to synthesize amorphous alloys in the Fe-Hf system. It turned out that in the samples with overall compositions located in the calculated GFR, amorphous phases were indeed obtained, whereas no amorphous phase was obtained if the overall compositions were located outside of the predicted region favoring for amorphous alloy formation, showing a good agreement between the experimental results and the thermodynamic calculation.

  6. 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

  7. 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

  8. 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.

  9. Analysis of the Range of Applicability of Thermodynamic Calculations in the Engineering of Nitride Fuel Elements

    Science.gov (United States)

    Ivanov, A. S.; Rusinkevich, A. A.; Belov, G. V.; Ivanov, Yu. A.

    2017-12-01

    The domains of applicability of thermodynamic calculations in the engineering of nitride fuel are analyzed. Characteristic values of the following parameters, which affect directly the concentration equilibration time, are estimated: nuclide production rate; characteristic times to local equilibrium in the considered temperature range; characteristic time needed for a stationary temperature profile to be established; characteristic time needed for a quasi-stationary concentration field to be established on a scale comparable to the size of a fuel pellet. It is demonstrated that equilibrium thermodynamic calculations are suitable for estimating the chemical and phase composition of fuel. However, a two-layer kinetic model should be developed in order to characterize the transport processes in condensed and gaseous phases. The process of diffusive transport needs to be taken into account in order to determine the composition in the hot region at the center of a fuel element.

  10. Thermodynamic and mechanical properties of TiC from ab initio calculation

    International Nuclear Information System (INIS)

    Dang, D. Y.; Fan, J. L.; Gong, H. R.

    2014-01-01

    The temperature-dependent thermodynamic and mechanical properties of TiC are systematically investigated by means of a combination of density-functional theory, quasi-harmonic approximation, and thermal electronic excitation. It is found that the quasi-harmonic Debye model should be pertinent to reflect thermodynamic properties of TiC, and the elastic properties of TiC decease almost linearly with the increase of temperature. Calculations also reveal that TiC possesses a pronounced directional pseudogap across the Fermi level, mainly due to the strong hybridization of Ti 3d and C 2p states. Moreover, the strong covalent bonding of TiC would be enhanced (reduced) with the decrease (increase) of temperature, while the change of volume (temperature) should have negligible effect on density of states at the Fermi level. The calculated results agree well with experimental observations in the literature.

  11. Thermodynamic calculation of the regions of stable existance of niobium nitride phases

    International Nuclear Information System (INIS)

    Chernyaev, V.V.; Mitrofanov, B.V.; Moiseev, G.K.; 6030000SU)

    1987-01-01

    Conditions of formation and stable existence of Nb 2 N and NbN niobium nitrides and the general picture of phase transformations in Nb-N system were determined in wide range of temperatures 1400-4000 K and pressures 10 -9 -10 MPa in result of thermodynamic analysis of Nb-N system using the program, realizing algorithm of total potential minimization. The sufficient nitrogen excess is necessary for formation of Nb 2 N and NbN especially. The temperature stability region and the temperature of NbN and Nb 2 N decomposition is shifted to high temperature region with pressure growth. Pressure region where niobium nitrides are stable, is shifted to high pressure region. The obtained calculation data correspond satisfactorily with experimental publication results. This testifies to possibility of using results of thermodynamic calculations for construction of p-T-diagrams of Nb-N system state

  12. First-principles calculations, experimental study, and thermodynamic modeling of the Al-Co-Cr system.

    Directory of Open Access Journals (Sweden)

    Xuan L Liu

    Full Text Available The phase relations and thermodynamic properties of the condensed Al-Co-Cr ternary alloy system are investigated using first-principles calculations based on density functional theory (DFT and phase-equilibria experiments that led to X-ray diffraction (XRD and electron probe micro-analysis (EPMA measurements. A thermodynamic description is developed by means of the calculations of phase diagrams (CALPHAD method using experimental and computational data from the present work and the literature. Emphasis is placed on modeling the bcc-A2, B2, fcc-γ, and tetragonal-σ phases in the temperature range of 1173 to 1623 K. Liquid, bcc-A2 and fcc-γ phases are modeled using substitutional solution descriptions. First-principles special quasirandom structures (SQS calculations predict a large bcc-A2 (disordered/B2 (ordered miscibility gap, in agreement with experiments. A partitioning model is then used for the A2/B2 phase to effectively describe the order-disorder transitions. The critically assessed thermodynamic description describes all phase equilibria data well. A2/B2 transitions are also shown to agree well with previous experimental findings.

  13. Thermodynamic calculations of self- and hetero-diffusion parameters in germanium

    International Nuclear Information System (INIS)

    Saltas, V.; Vallianatos, F.

    2015-01-01

    In the present work, the diffusion coefficients of n- and p-type dopants (P, As, Sb, Al) and self-diffusion in crystalline germanium are calculated from the bulk elastic properties of the host material based on the cBΩ thermodynamic model. The calculated diffusion coefficients as a function of temperature and the activation enthalpies prove to be in full agreement with the reported experimental results. Additional point defect parameters such as activation entropy, activation volume and activation Gibbs free energy are also calculated for each diffusing element. The pressure dependence of self-diffusion coefficients in germanium is also verified at high temperatures (876 K–1086 K), in agreement with reported results ranging from ambient pressure up to 600 MPa and is further calculated at pressures up to 3 GPa, where the phase transition to Ge II occurs. - Highlights: • Calculation of diffusivities of n- and p-type dopants in Ge from elastic properties. • Calculation of point defect parameters according to the cBΩ thermodynamic model. • Prediction of the pressure dependence of self-diffusion coefficients in Ge

  14. A spreadsheet-coupled SOLGAS: A computerized thermodynamic equilibrium calculation tool. Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    Trowbridge, L.D.; Leitnaker, J.M. [Oak Ridge K-25 Site, TN (United States). Technical Analysis and Operations Div.

    1995-07-01

    SOLGAS, an early computer program for calculating equilibrium in a chemical system, has been made more user-friendly, and several ``bells and whistles`` have been added. The necessity to include elemental species has been eliminated. The input of large numbers of starting conditions has been automated. A revised spreadsheet-based format for entering data, including non-ideal binary and ternary mixtures, simplifies and reduces chances for error. Calculational errors by SOLGAS are flagged, and several programming errors are corrected. Auxiliary programs are available to assemble and partially automate plotting of large amounts of data. Thermodynamic input data can be changed on line. The program can be operated with or without a co-processor. Copies of the program, suitable for the IBM-PC or compatibles with at least 384 bytes of low RAM, are available from the authors. This user manual contains appendices with examples of the use of SOLGAS. These range from elementary examples, such as, the relationships among water, ice, and water vapor, to more complex systems: phase diagram calculation of UF{sub 4} and UF{sub 6} system; burning UF{sub 4} in fluorine; thermodynamic calculation of the Cl-F-O-H system; equilibria calculations in the CCl{sub 4}--CH{sub 3}OH system; and limitations applicable to aqueous solutions. An appendix also contains the source code.

  15. Calculating Stress: From Entropy to a Thermodynamic Concept of Health and Disease

    Science.gov (United States)

    Nečesánek, Ivo; Konečný, David; Vasku, Anna

    2016-01-01

    To date, contemporary science has lacked a satisfactory tool for the objective expression of stress. This text thus introduces a new–thermodynamically derived–approach to stress measurement, based on entropy production in time and independent of the quality or modality of a given stressor or a combination thereof. Hereto, we propose a novel model of stress response based on thermodynamic modelling of entropy production, both in the tissues/organs and in regulatory feedbacks. Stress response is expressed in our model on the basis of stress entropic load (SEL), a variable we introduced previously; the mathematical expression of SEL, provided here for the first time, now allows us to describe the various states of a living system, including differentiating between states of health and disease. The resulting calculation of stress response regardless of the type of stressor(s) in question is thus poised to become an entirely new tool for predicting the development of a living system. PMID:26771542

  16. Thermodynamics

    International Nuclear Information System (INIS)

    Zanchini, E.

    1988-01-01

    The definition of energy, in thermodynamics, is dependent by starting operative definitions of the basic concepts of physics on which it rests, such as those of isolated systems, ambient of a system, separable system and set of separable states. Then the definition of energy is rigorously extended to open systems. The extension gives a clear physical meaning to the concept of energy difference between two states with arbitrary different compositions

  17. 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.

  18. 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.

  19. Hydrogen interaction with ferrite/cementite interface: ab initio calculations and thermodynamics

    Science.gov (United States)

    Mirzoev, A. A.; Verkhovykh, A. V.; Okishev, K. Yu.; Mirzaev, D. A.

    2018-02-01

    The paper presents the results of ab initio modelling of the interaction of hydrogen atoms with ferrite/cementite interfaces in steels and thermodynamic assessment of the ability of interfaces to trap hydrogen atoms. Modelling was performed using the density functional theory with generalised gradient approximation (GGA'96), as implemented in WIEN2k package. An Isaichev-type orientation relationship between the two phases was accepted, with a habit plane (101)c ∥ (112)α. The supercell contained 64 atoms (56 Fe and 8 C). The calculated formation energies of ferrite/cementite interface were 0.594 J/m2. The calculated trapping energy at cementite interstitial was 0.18 eV, and at the ferrite/cementite interface - 0.30 eV. Considering calculated zero-point energy, the trapping energies at cementite interstitial and ferrite/cementite interface become 0.26 eV and 0.39 eV, respectively. The values are close to other researchers' data. These results were used to construct a thermodynamic description of ferrite/cementite interface-hydrogen interaction. Absorption calculations using the obtained trapping energy values showed that even thin lamellar ferrite/cementite mixture with an interlamellar spacing smaller than 0.1 μm has noticeable hydrogen trapping ability at a temperature below 400 K.

  20. Computational Calorimetry: High-Precision Calculation of Host–Guest Binding Thermodynamics

    Science.gov (United States)

    2015-01-01

    We present a strategy for carrying out high-precision calculations of binding free energy and binding enthalpy values from molecular dynamics simulations with explicit solvent. The approach is used to calculate the thermodynamic profiles for binding of nine small molecule guests to either the cucurbit[7]uril (CB7) or β-cyclodextrin (βCD) host. For these systems, calculations using commodity hardware can yield binding free energy and binding enthalpy values with a precision of ∼0.5 kcal/mol (95% CI) in a matter of days. Crucially, the self-consistency of the approach is established by calculating the binding enthalpy directly, via end point potential energy calculations, and indirectly, via the temperature dependence of the binding free energy, i.e., by the van’t Hoff equation. Excellent agreement between the direct and van’t Hoff methods is demonstrated for both host–guest systems and an ion-pair model system for which particularly well-converged results are attainable. Additionally, we find that hydrogen mass repartitioning allows marked acceleration of the calculations with no discernible cost in precision or accuracy. Finally, we provide guidance for accurately assessing numerical uncertainty of the results in settings where complex correlations in the time series can pose challenges to statistical analysis. The routine nature and high precision of these binding calculations opens the possibility of including measured binding thermodynamics as target data in force field optimization so that simulations may be used to reliably interpret experimental data and guide molecular design. PMID:26523125

  1. Statistical thermodynamics

    International Nuclear Information System (INIS)

    Hwang, Jeong Ui; Jang, Jong Jae; Jee, Jong Gi

    1987-01-01

    The contents of this book are thermodynamics on the law of thermodynamics, classical thermodynamics and molecule thermodynamics, basics of molecule thermodynamics, molecule and assembly partition function, molecule partition function, classical molecule partition function, thermodynamics function for ideal assembly in fixed system, thermodynamics function for ideal assembly in running system, Maxwell-Boltzmann's law of distribution, chemical equilibrium like calculation of equilibrium constant and theory of absolute reaction rate.

  2. Update of a thermodynamic database for radionuclides to assist solubility limits calculation for performance assessment

    Energy Technology Data Exchange (ETDEWEB)

    Duro, L.; Grive, M.; Cera, E.; Domenech, C.; Bruno, J. (Enviros Spain S.L., Barcelona (ES))

    2006-12-15

    This report presents and documents the thermodynamic database used in the assessment of the radionuclide solubility limits within the SR-Can Exercise. It is a supporting report to the solubility assessment. Thermodynamic data are reviewed for 20 radioelements from Groups A and B, lanthanides and actinides. The development of this database is partially based on the one prepared by PSI and NAGRA. Several changes, updates and checks for internal consistency and completeness to the reference NAGRA-PSI 01/01 database have been conducted when needed. These modifications are mainly related to the information from the various experimental programmes and scientific literature available until the end of 2003. Some of the discussions also refer to a previous database selection conducted by Enviros Spain on behalf of ANDRA, where the reader can find additional information. When possible, in order to optimize the robustness of the database, the description of the solubility of the different radionuclides calculated by using the reported thermodynamic database is tested in front of experimental data available in the open scientific literature. When necessary, different procedures to estimate gaps in the database have been followed, especially accounting for temperature corrections. All the methodologies followed are discussed in the main text

  3. Update of a thermodynamic database for radionuclides to assist solubility limits calculation for performance assessment

    International Nuclear Information System (INIS)

    Duro, L.; Grive, M.; Cera, E.; Domenech, C.; Bruno, J.

    2006-12-01

    This report presents and documents the thermodynamic database used in the assessment of the radionuclide solubility limits within the SR-Can Exercise. It is a supporting report to the solubility assessment. Thermodynamic data are reviewed for 20 radioelements from Groups A and B, lanthanides and actinides. The development of this database is partially based on the one prepared by PSI and NAGRA. Several changes, updates and checks for internal consistency and completeness to the reference NAGRA-PSI 01/01 database have been conducted when needed. These modifications are mainly related to the information from the various experimental programmes and scientific literature available until the end of 2003. Some of the discussions also refer to a previous database selection conducted by Enviros Spain on behalf of ANDRA, where the reader can find additional information. When possible, in order to optimize the robustness of the database, the description of the solubility of the different radionuclides calculated by using the reported thermodynamic database is tested in front of experimental data available in the open scientific literature. When necessary, different procedures to estimate gaps in the database have been followed, especially accounting for temperature corrections. All the methodologies followed are discussed in the main text

  4. Criteria for compilation of a site-specific thermodynamic database for geochemical speciation calculations

    International Nuclear Information System (INIS)

    Chandratillake, M.; Trivedi, D.P.; Randall, M.G.; Humphreys, P.N.

    1998-01-01

    A methodology has been developed to establish a site-specific database appropriate to geochemical modelling the critical components and the wide range of near field conditions expected in the low level radioactive waste disposal site at Drigg in the UK. Several databases available in the public domain have been compared to select a foundation database. The foundation database was 'trimmed-down' and then customised to suit Drigg applications. The species dominant at Drigg have been identified and the thermodynamic constants of these species have been critically evaluated. The evaluated database has been validated for quality by comparing speciation calculations with plutonium and uranium experimental solubility results. (orig.)

  5. Theoretical calculations of the thermodynamic stability of ionic substitutions in hydroxyapatite under an aqueous solution environment

    International Nuclear Information System (INIS)

    Matsunaga, Katsuyuki; Murata, Hidenobu; Shitara, Kazuki

    2010-01-01

    Defect formation energies in materials generally depend on chemical potentials determined by a chemical equilibrium condition. In particular, an aqueous solution environment is important for biomaterials such as hydroxyapatite studied here. Therefore, a methodology to obtain ionic chemical potentials under chemical equilibrium between solid and aqueous solution was introduced, and was applied to substitutional divalent cations formed via ion exchange with Ca 2+ in hydroxyapatite. The calculated ranking of the stability of substitutional cations in HAp was in good agreement with the experimentally observed trend. The present theoretical approach would be useful to explore the thermodynamic stability of defects in materials subjected to an aqueous solution environment.

  6. Implementation of a Thermodynamic Solver within a Computer Program for Calculating Fission-Product Release Fractions

    Science.gov (United States)

    Barber, Duncan Henry

    During some postulated accidents at nuclear power stations, fuel cooling may be impaired. In such cases, the fuel heats up and the subsequent increased fission-gas release from the fuel to the gap may result in fuel sheath failure. After fuel sheath failure, the barrier between the coolant and the fuel pellets is lost or impaired, gases and vapours from the fuel-to-sheath gap and other open voids in the fuel pellets can be vented. Gases and steam from the coolant can enter the broken fuel sheath and interact with the fuel pellet surfaces and the fission-product inclusion on the fuel surface (including material at the surface of the fuel matrix). The chemistry of this interaction is an important mechanism to model in order to assess fission-product releases from fuel. Starting in 1995, the computer program SOURCE 2.0 was developed by the Canadian nuclear industry to model fission-product release from fuel during such accidents. SOURCE 2.0 has employed an early thermochemical model of irradiated uranium dioxide fuel developed at the Royal Military College of Canada. To overcome the limitations of computers of that time, the implementation of the RMC model employed lookup tables to pre-calculated equilibrium conditions. In the intervening years, the RMC model has been improved, the power of computers has increased significantly, and thermodynamic subroutine libraries have become available. This thesis is the result of extensive work based on these three factors. A prototype computer program (referred to as SC11) has been developed that uses a thermodynamic subroutine library to calculate thermodynamic equilibria using Gibbs energy minimization. The Gibbs energy minimization requires the system temperature (T) and pressure (P), and the inventory of chemical elements (n) in the system. In order to calculate the inventory of chemical elements in the fuel, the list of nuclides and nuclear isomers modelled in SC11 had to be expanded from the list used by SOURCE 2.0. A

  7. The elastic and thermodynamic properties of ZrMo2 from first principles calculations

    International Nuclear Information System (INIS)

    Liu, Xian-Kun; Zhou, Wei; Zheng, Zhou; Peng, Shu-Ming

    2014-01-01

    Highlights: • Elastic and thermodynamic properties of ZrMo 2 under high temperature and pressure are calculated by first principles. • Mechanical stability is testified from elastic constants at zero pressure. • Phonon scattering of ZrMo 2 under different temperature are obtained. - Abstract: The elastic and thermodynamic properties of ZrMo 2 under high temperature and pressure are investigated by first-principles calculations based on pseudopotential plane-wave density functional theory (DFT) within the generalized gradient approximation (GGA) and quasi-harmonic Debye model. The calculated lattice parameters are in good agreement with the available experimental data. The calculated elastic constants of ZrMo 2 increase monotonically with increasing pressure, and the relationship between the elastic constants and pressure show that ZrMo 2 satisfies the mechanical stability criteria under applied pressure (0–65 GPa). The related mechanical properties such as bulk modulus (B), shear modulus (G), Young’s modulus (E), and Poisson’s ratio (v) are also studied for polycrystalline of ZrMo 2 . The calculated B/G value shows that ZrMo 2 behaves in a ductile manner, and higher pressure can significantly improve the ductility of ZrMo 2 . The pressure and temperature dependencies of the relative volume, the bulk modulus, the elastic constants, the heat capacity and the thermal expansion coefficient, as well as the Grüneisen parameters are obtained and discussed by the quasi-harmonic Debye model in the ranges of 0–1800 K and 0–65 GPa

  8. 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.

  9. Thermodynamic description of the Al-Cu-Yb ternary system supported by first-principles calculations

    Directory of Open Access Journals (Sweden)

    Huang G.

    2016-01-01

    Full Text Available Phase relationships of the ternary Al-Cu-Yb system have been assessed using a combination of CALPHAD method and first principles calculations. A self-consistent thermodynamic parameter was established based on the experimental and theoretical information. Most of the binary intermetallic phases, except Al3Yb, Al2Yb, Cu2Yb and Cu5Yb, were assumed to be zero solubility in the ternary system. Based on the experimental data, eight ternary intermetallic compounds were taken into consideration in this system. Among them, three were treated as line compounds with large homogeneity ranges for Al and Cu. The others were treated as stoichiometric compounds. The calculated phase diagrams were in agreement with available experimental and theoretical data.

  10. Internet calculations of thermodynamic properties of substances: Some problems and results

    International Nuclear Information System (INIS)

    Ustyuzhanin, E E; Ochkov, V F; Shishakov, V V; Rykov, S V

    2016-01-01

    Internet resources (databases, web sites and others) on thermodynamic properties R = ( p,T,s ,...) of technologically important substances are analyzed. These databases put online by a number of organizations (the Joint Institute for High Temperatures of the Russian Academy of Sciences, Standartinform, the National Institute of Standards and Technology USA, the Institute for Thermal Physics of the Siberian Branch of the Russian Academy of Sciences, etc ) are investigated. Software codes are elaborated in the work in forms of “client functions” those have such characteristics: (i) they are placed on a remote server, (ii) they serve as open interactive Internet resources. A client can use them for a calculation of R properties of substances. “Complex client functions” are considered. They are focused on sharing (i) software codes elaborated to design of power plants (PP) and (ii) client functions those can calculate R properties of working fluids for PP. (paper)

  11. Phase stability and tensile properties of Co-free Al0.5CrCuFeNi2 high-entropy alloys

    International Nuclear Information System (INIS)

    Ng, Chun; Guo, Sheng; Luan, Junhua; Wang, Qing; Lu, Jian; Shi, Sanqiang; Liu, C.T.

    2014-01-01

    Highlights: • The solid solution phase in the high-entropy alloy was confirmed to be metastable. • The alloy exhibited microstructural and mechanical stability against annealing. • Only as-cast alloys showed sufficient tensile plasticity. • A large variability of the measured tensile properties was recorded. • The alloys showing slip banding behavior did not necessarily have tensile ductility. -- Abstract: High-entropy alloys (HEAs) are becoming new research frontiers in the metallic materials field. The phase stability of HEAs is of critical significance, but a convincing understanding on it has been somewhat held back by the slow diffusion kinetics, which prevents the completion of diffusion assisted phase transformations toward the equilibrium state. Here a unique methodology, combining both the thermomechanical treatments and thermodynamic calculations, was employed to reveal the phase stability of HEAs, exemplified using the newly developed Al 0.5 CrCuFeNi 2 alloy. The metastable nature of the solid solution phases in this high-entropy alloy was uncovered through thermomechanical treatments induced phase transformations, and supported by the thermodynamic calculations. Meanwhile, the tensile properties for both the as-cast and thermomechanically treated alloys were measured, and correlated to their indentation behavior

  12. Phase stability and electronic structure of transition-metal aluminides

    International Nuclear Information System (INIS)

    Carlsson, A.E.

    1992-01-01

    This paper will describe the interplay between die electronic structure and structural energetics in simple, complex, and quasicrystalline Al-transition metal (T) intermetallics. The first example is the Ll 2 -DO 22 competition in Al 3 T compounds. Ab-initio electronic total-energy calculations reveal surprisingly large structural-energy differences, and show that the phase stability of both stoichiometric and ternary-substituted compounds correlates closely with a quasigap in the electronic density of states (DOS). Secondly, ab-initio calculations for the structural stability of the icosahedrally based Al 12 W structure reveal similar quasigap effects, and provide a simple physical explanation for the stability of the complex aluminide structures. Finally, parametrized tight-binding model calculations for the Al-Mn quasicrystal reveal a large spread in the local Mn DOS behavior, and support a two-site model for the quasicrystal's magnetic behavior

  13. Calculations of thermodynamic properties of PuO{sub 2} by the first-principles and lattice vibration

    Energy Technology Data Exchange (ETDEWEB)

    Minamoto, Satoshi [Energy and Industrial Systems Department, ITOCHU Techno-Solutions Corporation, Kasumigaseki 3-chome, Chiyoda-ku, Tokyo 100-6080 (Japan)], E-mail: satoshi.minamoto@ctc-g.co.jp; Kato, Masato [Japan Atomic Energy Agency, 4-33 Muramatsu, Tokai-mura, Naka-gun, Ibaraki 319-1194 (Japan); Konashi, Kenji [Institute for Materials Research, Tohoku University, 2145-2 Narita-chou, Oarai-chou, Ibaraki 311-1313 (Japan); Kawazoe, Yoshiyuki [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

    2009-03-15

    Plutonium dioxide (PuO{sub 2}) is a key compound of mixed oxide fuel (MOX fuel). To predict the thermal properties of PuO{sub 2} at high temperature, it is important to understand the properties of MOX fuel. In this study, thermodynamic properties of PuO{sub 2} were evaluated by coupling of first-principles and lattice dynamics calculation. Cohesive energy was estimated from first-principles calculations, and the contribution of lattice vibration to total energy was evaluated by phonon calculations. Thermodynamic properties such as volume thermal expansion, bulk modulus and specific heat of PuO{sub 2} were investigated up to 1500 K.

  14. Calculations of thermodynamic properties of PuO2 by the first-principles and lattice vibration

    International Nuclear Information System (INIS)

    Minamoto, Satoshi; Kato, Masato; Konashi, Kenji; Kawazoe, Yoshiyuki

    2009-01-01

    Plutonium dioxide (PuO 2 ) is a key compound of mixed oxide fuel (MOX fuel). To predict the thermal properties of PuO 2 at high temperature, it is important to understand the properties of MOX fuel. In this study, thermodynamic properties of PuO 2 were evaluated by coupling of first-principles and lattice dynamics calculation. Cohesive energy was estimated from first-principles calculations, and the contribution of lattice vibration to total energy was evaluated by phonon calculations. Thermodynamic properties such as volume thermal expansion, bulk modulus and specific heat of PuO 2 were investigated up to 1500 K

  15. Thermodynamic calculation of simultaneous reactions of n-butane isomerization and isobutane alkylation with ethylene

    Energy Technology Data Exchange (ETDEWEB)

    Batyrshin, N.N.; Beresneva, L.D.; Sidorov, V.A.

    1981-08-01

    Industrial production of ethylene alkylate has gained further development in connection with worldwide ecological problems and the planned changeover of automobile transport to unleaded gasolines, but the scale of production is still substantially less than that of sulfuric acid or hydrogen fluoride alkylates. This is due both to the instability of market prices for ethylene and the shortage of isobutane - a raw material for these large-tonnage production processes and for the synthetic rubber industry. The latter difficulty can be overcome by combining processes of isomerization of n-butane and alkylation of the resultant isobutane with ethylene in a single reaction unit. The possibility of combining these reactions using AlCl/sub 3/-based catalysts has been pointed out previously but in the literature there are no theoretical developments of technology or thermodynamic substantiation of a combined process. We have made a thermodynamic calculation of the consecutive (series-parallel) reactions of isomerization and alkylation with the goal of determining suitable technological conditions for carrying them out simultaneously and establishing the expected equilibrium yields of target products and the compositions of the reaction mixture.

  16. 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.)

  17. Mechanical, electronic, and thermodynamic properties of zirconium carbide from first-principles calculations

    Science.gov (United States)

    Yang, Xiao-Yong; Lu, Yong; Zheng, Fa-Wei; Zhang, Ping

    2015-11-01

    Mechanical, electronic, and thermodynamic properties of zirconium carbide have been systematically studied using the ab initio calculations. The calculated equilibrium lattice parameter, bulk modulus, and elastic constants are all well consistent with the experimental data. The electronic band structure indicates that the mixture of C 2p and Zr 4d and 4p orbitals around the Fermi level makes a large covalent contribution to the chemical bonds between the C and Zr atoms. The Bader charge analysis suggests that there are about 1.71 electrons transferred from each Zr atom to its nearest C atom. Therefore, the Zr-C bond displays a mixed ionic/covalent character. The calculated phonon dispersions of ZrC are stable, coinciding with the experimental measurement. A drastic expansion in the volume of ZrC is seen with increasing temperature, while the bulk modulus decreases linearly. Based on the calculated phonon dispersion curves and within the quasi-harmonic approximation, the temperature dependence of the heat capacities is obtained, which gives a good description compared with the available experimental data. Project supported by the National Natural Science Foundation of China (Grant No. 51071032).

  18. Thermodynamic properties calculation of the flue gas based on its composition estimation for coal-fired power plants

    International Nuclear Information System (INIS)

    Xu, Liang; Yuan, Jingqi

    2015-01-01

    Thermodynamic properties of the working fluid and the flue gas play an important role in the thermodynamic calculation for the boiler design and the operational optimization in power plants. In this study, a generic approach to online calculate the thermodynamic properties of the flue gas is proposed based on its composition estimation. It covers the full operation scope of the flue gas, including the two-phase state when the temperature becomes lower than the dew point. The composition of the flue gas is online estimated based on the routinely offline assays of the coal samples and the online measured oxygen mole fraction in the flue gas. The relative error of the proposed approach is found less than 1% when the standard data set of the dry and humid air and the typical flue gas is used for validation. Also, the sensitivity analysis of the individual component and the influence of the measurement error of the oxygen mole fraction on the thermodynamic properties of the flue gas are presented. - Highlights: • Flue gas thermodynamic properties in coal-fired power plants are online calculated. • Flue gas composition is online estimated using the measured oxygen mole fraction. • The proposed approach covers full operation scope, including two-phase flue gas. • Component sensitivity to the thermodynamic properties of flue gas is presented.

  19. Ab initio calculation of the thermodynamic properties of InSb under intense laser irradiation

    International Nuclear Information System (INIS)

    Feng, ShiQuan; Cheng, XinLu; Zhao, JianLing; Zhang, Hong

    2013-01-01

    In this paper, phonon spectra of InSb at different electronic temperatures are presented. Based on the phonon dispersion relationship, we further perform a theoretical investigation of the thermodynamic properties of InSb under intense laser irradiation. The phonon entropy, phonon heat capacity, and phonon contribution to Helmholtz free energy and internal energy of InSb are calculated as functions of temperature at different electronic temperatures. The abrupt change in the phonon entropy- temperature curve from T e = 0.75 to 1.0 eV provides an indication of InSb undergoing a phase transition from solid to liquid. It can be considered as a collateral evidence of non-thermal melting for InSb under intense electronic excitation effect

  20. Ab initio calculation of the thermodynamic properties of InSb under intense laser irradiation

    Science.gov (United States)

    Feng, ShiQuan; Zhao, JianLing; Cheng, XinLu; Zhang, Hong

    2013-07-01

    In this paper, phonon spectra of InSb at different electronic temperatures are presented. Based on the phonon dispersion relationship, we further perform a theoretical investigation of the thermodynamic properties of InSb under intense laser irradiation. The phonon entropy, phonon heat capacity, and phonon contribution to Helmholtz free energy and internal energy of InSb are calculated as functions of temperature at different electronic temperatures. The abrupt change in the phonon entropy- temperature curve from Te = 0.75 to 1.0 eV provides an indication of InSb undergoing a phase transition from solid to liquid. It can be considered as a collateral evidence of non-thermal melting for InSb under intense electronic excitation effect.

  1. Exact Calculation of the Thermodynamics of Biomacromolecules on Cubic Recursive Lattice.

    Science.gov (United States)

    Huang, Ran

    The thermodynamics of biomacromolecules featured as foldable polymer with inner-linkage of hydrogen bonds, e. g. protein, RNA and DNA, play an impressive role in either physical, biological, and polymer sciences. By treating the foldable chains to be the two-tolerate self-avoiding trails (2T polymer), abstract lattice modeling of these complex polymer systems to approach their thermodynamics and subsequent bio-functional properties have been developed for decades. Among these works, the calculations modeled on Bethe and Husimi lattice have shown the excellence of being exactly solvable. Our project extended this effort into the 3D situation, i.e. the cubic recursive lattice. The preliminary exploration basically confirmed others' previous findings on the planar structure, that we have three phases in the grand-canonical phase diagram, with a 1st order transition between non-polymerized and polymer phases, and a 2nd order transition between two distinguishable polymer phases. However the hydrogen bond energy J, stacking energy ɛ, and chain rigidity energy H play more vigorous effects on the thermal behaviors, and this is hypothesized to be due to the larger number of possible configurations provided by the complicated 3D model. By the so far progress, the calculation of biomacromolecules may be applied onto more complex recursive lattices, such as the inhomogeneous lattice to describe the cross-dimensional situations, and beside the thermal properties of the 2T polymers, we may infer some interesting insights of the mysterious folding problem itself. National Natural Science Foundation of China.

  2. First principles calculation of thermodynamic properties of NaAlSi ternary

    International Nuclear Information System (INIS)

    Qin Jining; Lu Weijie; Zhang Di; Fan Tongxiang

    2012-01-01

    PbFCl-type NaAlSi ternary is a corrosion compound found in aluminum, which is used as a sealing material in sodium sulfur battery. To understand and control the corrosion process, it is important to predict its quantitative properties. In this study, a first-principles calculation has been carried out to calculate its equilibrium lattice parameters, bulk modulus and pressure derivative of bulk modulus by both all-electron full-potential linear augmented plane wave scheme and pseudopotential plane wave scheme within the generalized gradient approximation. The theoretical results show good agreement with the available experimental data. The thermodynamic properties, including the specific heat capacity and entropy with pressure up to 9 GPa, have been investigated for the first time by coupling of density functional perturbation theory and quasiharmonic approximation. The volume and linear thermal expansion coefficients were estimated and the results show that the linear thermal expansion on c-axis is nearly twice as large as that on a-axis within the calculated temperature.

  3. FORTRAN routines for calculating water thermodynamic properties for use in transient thermal-hydraulics codes

    International Nuclear Information System (INIS)

    Green, C.

    1979-12-01

    A set of FORTRAN subroutines is described for calculating water thermodynamic properties. These were written for use in a transient thermal-hydraulics program, where speed of execution is paramount. The choice of which subroutines to optimise depends on the primary variables in the thermal-hydraulics code. In this particular case the subroutine which has been optimised is the one which calculates pressure and specific enthalpy given the specific volume and the specific internal energy. Another two subroutines are described which complete a self-consistent set. These calculate the specific volume and the temperature given the pressure and the specific enthalpy, and the specific enthalpy and the specific volume given the pressure and the temperature (or the quality). The accuracy is high near the saturation lines, typically less than 1% relative error, and decreases as the fluid becomes more subcooled in the liquid region or more superheated in the steam region. This behaviour is inherent in the method which uses quantities defined on the saturation lines and assumes that certain derivatives are constant for excursions away from these saturation lines. The accuracy and speed of the subroutines are discussed in detail in this report. (author)

  4. Phase stabilities at a glance: Stability diagrams of nickel dipnictides

    International Nuclear Information System (INIS)

    Bachhuber, F.; Rothballer, J.; Weihrich, R.; Söhnel, T.

    2013-01-01

    In the course of the recent advances in chemical structure prediction, a straightforward type of diagram to evaluate phase stabilities is presented based on an expedient example. Crystal structures and energetic stabilities of dipnictides NiPn 2 (Pn = N, P, As, Sb, Bi) are systematically investigated by first principles calculations within the framework of density functional theory using the generalized gradient approximation to treat exchange and correlation. These dipnictides show remarkable polymorphism that is not yet understood systematically and offers room for the discovery of new phases. Relationships between the concerned structures including the marcasite, the pyrite, the arsenopyrite/CoSb 2 , and the NiAs 2 types are highlighted by means of common structural fragments. Electronic stabilities of experimentally known and related AB 2 structure types are presented graphically in so-called stability diagrams. Additionally, competing binary phases are taken into consideration in the diagrams to evaluate the stabilities of the title compounds with respect to decomposition. The main purpose of the stability diagrams is the introduction of an image that enables the estimation of phase stabilities at a single glance. Beyond that, some of the energetically favored structure types can be identified as potential new phases

  5. Effects of sulfur on lead partitioning during sludge incineration based on experiments and thermodynamic calculations

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jing-yong, E-mail: www053991@126.com [School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006 (China); Huang, Shu-jie; Sun, Shui-yu; Ning, Xun-an; He, Rui-zhe [School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006 (China); Li, Xiao-ming [Guangdong Testing Institute of Product Quality Supervision, Guangzhou 510330 (China); Chen, Tao [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Luo, Guang-qian [State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074 (China); Xie, Wu-ming; Wang, Yu-jie; Zhuo, Zhong-xu; Fu, Jie-wen [School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006 (China)

    2015-04-15

    Highlights: • A thermodynamic equilibrium calculation was carried out. • Effects of three types of sulfurs on Pb distribution were investigated. • The mechanism for three types of sulfurs acting on Pb partitioning were proposed. • Lead partitioning and species in bottom ash and fly ash were identified. - Abstract: Experiments in a tubular furnace reactor and thermodynamic equilibrium calculations were conducted to investigate the impact of sulfur compounds on the migration of lead (Pb) during sludge incineration. Representative samples of typical sludge with and without the addition of sulfur compounds were combusted at 850 °C, and the partitioning of Pb in the solid phase (bottom ash) and gas phase (fly ash and flue gas) was quantified. The results indicate that three types of sulfur compounds (S, Na{sub 2}S and Na{sub 2}SO{sub 4}) added to the sludge could facilitate the volatilization of Pb in the gas phase (fly ash and flue gas) into metal sulfates displacing its sulfides and some of its oxides. The effect of promoting Pb volatilization by adding Na{sub 2}SO{sub 4} and Na{sub 2}S was superior to that of the addition of S. In bottom ash, different metallic sulfides were found in the forms of lead sulfide, aluminosilicate minerals, and polymetallic-sulfides, which were minimally volatilized. The chemical equilibrium calculations indicated that sulfur stabilizes Pb in the form of PbSO{sub 4}(s) at low temperatures (<1000 K). The equilibrium calculation prediction also suggested that SiO{sub 2}, CaO, TiO{sub 2}, and Al{sub 2}O{sub 3} containing materials function as condensed phase solids in the temperature range of 800–1100 K as sorbents to stabilize Pb. However, in the presence of sulfur or chlorine or the co-existence of sulfur and chlorine, these sorbents were inactive. The effect of sulfur on Pb partitioning in the sludge incineration process mainly depended on the gas phase reaction, the surface reaction, the volatilization of products, and the

  6. Theory and modelling of nanocarbon phase stability.

    Energy Technology Data Exchange (ETDEWEB)

    Barnard, A. S.

    2006-01-01

    The transformation of nanodiamonds into carbon-onions (and vice versa) has been observed experimentally and has been modeled computationally at various levels of sophistication. Also, several analytical theories have been derived to describe the size, temperature and pressure dependence of this phase transition. However, in most cases a pure carbon-onion or nanodiamond is not the final product. More often than not an intermediary is formed, known as a bucky-diamond, with a diamond-like core encased in an onion-like shell. This has prompted a number of studies investigating the relative stability of nanodiamonds, bucky-diamonds, carbon-onions and fullerenes, in various size regimes. Presented here is a review outlining results of numerous theoretical studies examining the phase diagrams and phase stability of carbon nanoparticles, to clarify the complicated relationship between fullerenic and diamond structures at the nanoscale.

  7. Comparison of the thermodynamic databases for radioactive elements in application to the calculation of the solubilities in the porewater

    International Nuclear Information System (INIS)

    Doi, Reisuke; Shibata, Masahiro

    2006-07-01

    To calculate the solubility of radioactive elements which is the important parameter for performance assessment of geological disposal system, the thermodynamic database must be reliable and based on the latest information. In this research, it has been compared in the calculation of the solubilities of the representative radioactive elements in the porewater compositions of the compacted bentonite which were set up in the second progress report (H12) that the thermodynamic database of JNC, OECD/NEA, Nagra/PSI. And the causes of the differences among the results from application of different databases were investigated and discussed. (author)

  8. Structural and Thermodynamic Analysis of the First Mononuclear Aqueous Aluminum Citrate Complex Using DFT Calculations.

    Science.gov (United States)

    de Noronha, Antonio Luiz Oliveira; Guimarães, Luciana; Duarte, Hélio Anderson

    2007-05-01

    Structural and thermodynamic properties of the mononuclear Al/citrate complexes have been theoretically investigated aiming to understand the coordination mechanism at an atomic level. GGA-DFT/PCM calculations have been performed for the different conformations and tautomers arising from the Al(3+) and citric acid (H3L) interaction in aqueous solution. The Gibbs reaction energies were estimated based on the reaction of the trigonal planar Al(OH)3 and H3L to form different Al-citrate complexes. The estimated Gibbs free reaction energies for the [AlL], [AlHL](+), and [Al(OH)L](-) species are in good agreement with the experimental values. In these species, the Al(3+) center is coordinated by two carboxylic and the tertiary hydroxyl groups of the citrate. Conversely to what has been proposed based on the experiments, the present theoretical calculations indicate that the citric acid hydroxyl group remains protonated upon the coordination of Al(3+). In fact, our model turns out to be more consistent with the relative pKa values of citrate protonation groups and with the hydrolysis constant of the H2O bound to Al(3+) leading to better agreement with the available experimental data.

  9. Effects of sulfur on lead partitioning during sludge incineration based on experiments and thermodynamic calculations.

    Science.gov (United States)

    Liu, Jing-yong; Huang, Shu-jie; Sun, Shui-yu; Ning, Xun-an; He, Rui-zhe; Li, Xiao-ming; Chen, Tao; Luo, Guang-qian; Xie, Wu-ming; Wang, Yu-Jie; Zhuo, Zhong-xu; Fu, Jie-wen

    2015-04-01

    Experiments in a tubular furnace reactor and thermodynamic equilibrium calculations were conducted to investigate the impact of sulfur compounds on the migration of lead (Pb) during sludge incineration. Representative samples of typical sludge with and without the addition of sulfur compounds were combusted at 850 °C, and the partitioning of Pb in the solid phase (bottom ash) and gas phase (fly ash and flue gas) was quantified. The results indicate that three types of sulfur compounds (S, Na2S and Na2SO4) added to the sludge could facilitate the volatilization of Pb in the gas phase (fly ash and flue gas) into metal sulfates displacing its sulfides and some of its oxides. The effect of promoting Pb volatilization by adding Na2SO4 and Na2S was superior to that of the addition of S. In bottom ash, different metallic sulfides were found in the forms of lead sulfide, aluminosilicate minerals, and polymetallic-sulfides, which were minimally volatilized. The chemical equilibrium calculations indicated that sulfur stabilizes Pb in the form of PbSO4(s) at low temperatures (incineration process mainly depended on the gas phase reaction, the surface reaction, the volatilization of products, and the concentration of Si, Ca and Al-containing compounds in the sludge. These findings provide useful information for understanding the partitioning behavior of Pb, facilitating the development of strategies to control the volatilization of Pb during sludge incineration. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Accurate thermodynamic relations of the melting temperature of nanocrystals with different shapes and pure theoretical calculation

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Jinhua; Fu, Qingshan; Xue, Yongqiang, E-mail: xyqlw@126.com; Cui, Zixiang

    2017-05-01

    Based on the surface pre-melting model, accurate thermodynamic relations of the melting temperature of nanocrystals with different shapes (tetrahedron, cube, octahedron, dodecahedron, icosahedron, nanowire) were derived. The theoretically calculated melting temperatures are in relative good agreements with experimental, molecular dynamic simulation and other theoretical results for nanometer Au, Ag, Al, In and Pb. It is found that the particle size and shape have notable effects on the melting temperature of nanocrystals, and the smaller the particle size, the greater the effect of shape. Furthermore, at the same equivalent radius, the more the shape deviates from sphere, the lower the melting temperature is. The value of melting temperature depression of cylindrical nanowire is just half of that of spherical nanoparticle with an identical radius. The theoretical relations enable one to quantitatively describe the influence regularities of size and shape on the melting temperature and to provide an effective way to predict and interpret the melting temperature of nanocrystals with different sizes and shapes. - Highlights: • Accurate relations of T{sub m} of nanocrystals with various shapes are derived. • Calculated T{sub m} agree with literature results for nano Au, Ag, Al, In and Pb. • ΔT{sub m} (nanowire) = 0.5ΔT{sub m} (spherical nanocrystal). • The relations apply to predict and interpret the melting behaviors of nanocrystals.

  11. Structural, electronic, and thermodynamic properties of curium dioxide: Density functional theory calculations

    Science.gov (United States)

    Hou, Ling; Li, Wei-Dong; Wang, Fangwei; Eriksson, Olle; Wang, Bao-Tian

    2017-12-01

    We present a systematic investigation of the structural, magnetic, electronic, mechanical, and thermodynamic properties of CmO2 with the local density approximation (LDA)+U and the generalized gradient approximation (GGA)+U approaches. The strong Coulomb repulsion and the spin-orbit coupling (SOC) effects on the lattice structures, electronic density of states, and band gaps are carefully studied, and compared with other A O2 (A =U , Np, Pu, and Am). The ferromagnetic configuration with half-metallic character is predicted to be energetically stable while a charge-transfer semiconductor is predicted for the antiferromagnetic configuration. The elastic constants and phonon spectra show that the fluorite structure is mechanically and dynamically stable. Based on the first-principles phonon density of states, the lattice vibrational energy is calculated using the quasiharmonic approximation. Then, the Gibbs free energy, thermal expansion coefficient, specific heat, and entropy are obtained and compared with experimental data. The mode Grüneisen parameters are presented to analyze the anharmonic properties. The Slack relation is applied to obtain the lattice thermal conductivity in temperature range of 300-1600 K. The phonon group velocities are also calculated to investigate the heat transfer. For all these properties, if available, we compare the results of CmO2 with other A O2 .

  12. Real space multiple scattering description of alloy phase stability

    International Nuclear Information System (INIS)

    Turchi, P.E.A.; Sluiter, M.

    1992-01-01

    This paper presents a brief overview of the advanced methodology which has been recently developed to study phase stability properties of substitutional alloys, including order-disorder phenomena and structural transformations. The approach is based on the real space version of the Generalized Perturbation Method first introduced by Ducastelle and Gautier, within the Korringa-Kohn-Rostoker multiple scattering formulation of the Coherent Potential Approximation. Temperature effects are taken into account with a generalized meanfield approach, namely the Cluster Variation Method. The viability and the predictive power of such a scheme will be illustrated by a few examples, among them: the ground state properties of alloys, in particular the ordering tendencies for a series of equiatomic bcc-based alloys, the computation of alloy phase diagrams with the case of fcc and bcc-based Ni-Al alloys, the calculation of antiphase boundary energies and interfacial energies, and the stability of artificial ordered superlattices

  13. Thermodynamics and elastic properties of Ir from first-principle calculations

    International Nuclear Information System (INIS)

    Li Qiang; Huang Duohui; Cao Qilong; Wang Fanhou

    2013-01-01

    Within the framework of the quasiharmonic approximation, the thermodynamics and elastic properties, including phonon dispersion curves, equation of state, linear thermal expansion coefficient and temperature-dependent entropy, enthalpy, heat capacity, elastic constants, bulk modulus, shear modulus, Young's modulus of Ir have been studied using first-principles projector-augmented wave method. The results revealed that the predicted phonon dispersion curves of Ir are in agreement with the experimental measurements by neutron diffractions. Considering the thermal electronic contribution to Helmholtz free energy, the calculated entropy, enthalpy, heat capacity and linear thermal expansion co- efficient from the first-principle are consistent well with the experimental data. At 2600 K, the electronic heat capacity accounts for 17% of the total heat capacity at constant pressure, thus the thermal electronic contribution to Helmholtz free energy is very important. The predicted elastic constants, bulk modulus, shear modulus and Young's modulus at room temperature are also in agreement with the available measurements and increase with the increasing temperature. (authors)

  14. Automation of data processing and calculation of retention parameters and thermodynamic data for gas chromatography

    Science.gov (United States)

    Makarycheva, A. I.; Faerman, V. A.

    2017-02-01

    The analyses of automation patterns is performed and the programming solution for the automation of data processing of the chromatographic data and their further information storage with a help of a software package, Mathcad and MS Excel spreadsheets, is developed. The offered approach concedes the ability of data processing algorithm modification and does not require any programming experts participation. The approach provides making a measurement of the given time and retention volumes, specific retention volumes, a measurement of differential molar free adsorption energy, and a measurement of partial molar solution enthalpies and isosteric heats of adsorption. The developed solution is focused on the appliance in a small research group and is tested on the series of some new gas chromatography sorbents. More than 20 analytes were submitted to calculation of retention parameters and thermodynamic sorption quantities. The received data are provided in the form accessible to comparative analysis, and they are able to find sorbing agents with the most profitable properties to solve some concrete analytic issues.

  15. First-principles calculations of bulk and interfacial thermodynamic properties for fcc-based Al-Sc alloys

    International Nuclear Information System (INIS)

    Asta, M.; Foiles, S.M.; Quong, A.A.

    1998-01-01

    The configurational thermodynamic properties of fcc-based Al-Sc alloys and coherent Al/Al 3 Sc interphase-boundary interfaces have been calculated from first principles. The computational approach used in this study combines the results of pseudopotential total-energy calculations with a cluster-expansion description of the alloy energetics. Bulk and interface configurational-thermodynamic properties are computed using a low-temperature-expansion technique. Calculated values of the {100} and {111} Al/Al 3 Sc interfacial energies at zero temperature are, respectively, 192 and 226mJ/m 2 . The temperature dependence of the calculated interfacial free energies is found to be very weak for {100} and more appreciable for {111} orientations; the primary effect of configurational disordering at finite temperature is to reduce the degree of crystallographic anisotropy associated with calculated interfacial free energies. The first-principles-computed solid-solubility limits for Sc in bulk fcc Al are found to be underestimated significantly in comparison with experimental measurements. It is argued that this discrepancy can be largely attributed to nonconfigurational contributions to the entropy which have been neglected in the present thermodynamic calculations. copyright 1998 The American Physical Society

  16. Quantum chemical and thermodynamic calculations of fulvic and humic copper complexes in reactions of malachite and azurite formation

    International Nuclear Information System (INIS)

    Fomin, Vitaliy N.; Gogol, Daniil B.; Rozhkovoy, Ivan E.; Ponomarev, Dmitriy L.

    2017-01-01

    This article provides a thermodynamic evaluation of the reactions of humic and fulvic acids in the process of malachite and azurite mineralogenesis. Semi-empirical methods AM/1, MNDO, PM3, PM5, PM6 and PM7 were used to compute the heat of formation, enthalpy and entropy for thermodynamic calculations of the reactions performed on the basis of Hess's law. It is shown that methods PM6 and PM7 in the MOPAC software package provide good compliance with experimental and calculated heats of formation for copper complexes and alkaline earth metal complexes with organic acids. It is found that the malachite and azurite formation processes involving humus complexing substances are thermodynamically possible. - Highlights: • Copper and alkali-earth metal complexes with humic and fulvic acids are considered. • Quantum chemical calculation of thermodynamics for the structures was performed. • Semi-empirical methods PM6 and PM7 provide best correlation for the properties. • Parameters of basic copper carbonate formation reactions were obtained by Hess's law. • Processes of malachite and azurite formation from humus complexes are possible.

  17. Prediction of high-temperature point defect formation in TiO2 from combined ab initio and thermodynamic calculations

    International Nuclear Information System (INIS)

    He, J.; Behera, R.K.; Finnis, M.W.; Li, X.; Dickey, E.C.; Phillpot, S.R.; Sinnott, S.B.

    2007-01-01

    A computational approach that integrates ab initio electronic structure and thermodynamic calculations is used to determine point defect stability in rutile TiO 2 over a range of temperatures, oxygen partial pressures and stoichiometries. Both donors (titanium interstitials and oxygen vacancies) and acceptors (titanium vacancies) are predicted to have shallow defect transition levels in the electronic-structure calculations. The resulting defect formation energies for all possible charge states are then used in thermodynamic calculations to predict the influence of temperature and oxygen partial pressure on the relative stabilities of the point defects. Their ordering is found to be the same as temperature increases and oxygen partial pressure decreases: titanium vacancy → oxygen vacancy → titanium interstitial. The charges on these defects, however, are quite sensitive to the Fermi level. Finally, the combined formation energies of point defect complexes, including Schottky, Frenkel and anti-Frenkel defects, are predicted to limit the further formation of point defects

  18. Nanoscale Phase Stability Reversal During the Nucleation and Growth of Titanium Oxide Minerals

    Science.gov (United States)

    Hummmer, D. R.; Heaney, P. J.; Kubicki, J. D.; Kent, P. R.; Post, J. E.

    2008-12-01

    Fine-grained titanium oxide minerals are important in soils, where they affect a variety of geochemical processes. They are also industrially important as catalysts, pigments, food additives, and dielectrics. Recent research has indicated an apparent reversal of thermodynamic stability between TiO2 phases at the nanoscale thought to be caused by an increased contribution of surface energy to the total free energy. Time-resolved X-ray diffraction (XRD) experiments in which titanium oxides crystallize from aqueous TiCl4 solutions confirm that anatase, a metastable phase, is always the first phase to nucleate under our range of initial conditions. Rutile peaks are observed only minutes after the first appearance of anatase, after which anatase abundance slowly decreases while rutile continues to form. Whole pattern refinement of diffraction data reveals that lattice constants of both phases increase throughout the crystallization process. In addition, transmission electron microscope (TEM) observations and kinetic modeling indicate that anatase does not undergo a solid-state transformation to the rutile structure as once thought. Instead, anatase appears to re-dissolve and then feed the growth of already nucleated rutile nanocrystals. Density functional theory (DFT) calculations were employed to model 1, 2, and 3 nm particles of both mineral phases. The total surface energies calculated from these models did yield lower values for anatase than for rutile by 8-13 kJ/mol depending on particle size, indicating that surface free energy is sufficient to account for stability reversal. However, these whole-particle surface energies were much higher than the sum of energies of each particle's constituent crystallographic surfaces. We attribute the excess energy to defects associated with the edges and corners of nanoparticles, which are not present on a 2-D periodic surface. This previously unreported edge and corner energy may play a dominant role in the stability reversal

  19. Aging and Phase Stability of Waste Package Outer Barrier

    Energy Technology Data Exchange (ETDEWEB)

    F. Wong

    2004-09-28

    This report was prepared in accordance with ''Technical Work Plan for: Regulatory Integration Modeling and Analysis of the Waste Form and Waste Package'' (BSC 2004 [DIRS 171583]). This report provides information on the phase stability of Alloy 22, the current waste package outer barrier material. The goal of this model is to determine whether the single-phase solid solution is stable under repository conditions and, if not, how fast other phases may precipitate. The aging and phase stability model, which is based on fundamental thermodynamic and kinetic concepts and principles, will be used to provide predictive insight into the long-term metallurgical stability of Alloy 22 under relevant repository conditions. The results of this model are used by ''General Corrosion and Localized Corrosion of Waste Package Outer Barrier'' as reference-only information. These phase stability studies are currently divided into three general areas: Tetrahedrally close-packed (TCP) phase and carbide precipitation in the base metal; TCP and carbide precipitation in welded samples; and Long-range ordering reactions. TCP-phase and carbide precipitates that form in Alloy 22 are generally rich in chromium (Cr) and/or molybdenum (Mo) (Raghavan et al. 1984 [DIRS 154707]). Because these elements are responsible for the high corrosion resistance of Alloy 22, precipitation of TCP phases and carbides, especially at grain boundaries, can lead to an increased susceptibility to localized corrosion in the alloy. These phases are brittle and also tend to embrittle the alloy (Summers et al. 1999 [DIRS 146915]). They are known to form in Alloy 22 at temperatures greater than approximately 600 C. Whether these phases also form at the lower temperatures expected in the repository during the 10,000-year regulatory period must be determined. The kinetics of this precipitation will be determined for both the base metal and the weld heat-affected zone (HAZ). The TCP

  20. Aging and Phase Stability of Waste Package Outer Barrier

    International Nuclear Information System (INIS)

    F. Wong

    2004-01-01

    This report was prepared in accordance with ''Technical Work Plan for: Regulatory Integration Modeling and Analysis of the Waste Form and Waste Package'' (BSC 2004 [DIRS 171583]). This report provides information on the phase stability of Alloy 22, the current waste package outer barrier material. The goal of this model is to determine whether the single-phase solid solution is stable under repository conditions and, if not, how fast other phases may precipitate. The aging and phase stability model, which is based on fundamental thermodynamic and kinetic concepts and principles, will be used to provide predictive insight into the long-term metallurgical stability of Alloy 22 under relevant repository conditions. The results of this model are used by ''General Corrosion and Localized Corrosion of Waste Package Outer Barrier'' as reference-only information. These phase stability studies are currently divided into three general areas: Tetrahedrally close-packed (TCP) phase and carbide precipitation in the base metal; TCP and carbide precipitation in welded samples; and Long-range ordering reactions. TCP-phase and carbide precipitates that form in Alloy 22 are generally rich in chromium (Cr) and/or molybdenum (Mo) (Raghavan et al. 1984 [DIRS 154707]). Because these elements are responsible for the high corrosion resistance of Alloy 22, precipitation of TCP phases and carbides, especially at grain boundaries, can lead to an increased susceptibility to localized corrosion in the alloy. These phases are brittle and also tend to embrittle the alloy (Summers et al. 1999 [DIRS 146915]). They are known to form in Alloy 22 at temperatures greater than approximately 600 C. Whether these phases also form at the lower temperatures expected in the repository during the 10,000-year regulatory period must be determined. The kinetics of this precipitation will be determined for both the base metal and the weld heat-affected zone (HAZ). The TCP phases (P, μ, and σ) are present in

  1. Investigating the Thermal and Phase Stability of Nanocrystalline Ni-W Produced by Electrodeposition, Sputtering, and Mechanical Alloying

    Science.gov (United States)

    Marvel, Christopher Jonathan

    diffusivity calculations conceptually suggested that increasing W alloying concentrations can decrease the grain growth rate. The strongest evidence of grain growth stagnation was via nanoscale oxide particle drag in highly contaminated electrodeposited alloys. Interestingly, W-segregation was also detected to the oxide phase boundaries and revealed a potential indirect mechanism of thermal stability. The phase stability of pure and contaminated Ni-W alloys was investigated with density functional theory. Primarily, the calculations suggested that the intermetallic phases NiW and NiW2 are thermodynamically unstable, meaning the binary phase diagram is incorrect, but the ternary carbides Ni 6W6C and Ni2W4C are stable. Several Ni-W binary and Ni-W-C ternary phase diagrams were constructed using a simplified CALPHAD approach to improve the understanding of Ni-W phase stability. Lastly, it was determined that the fabrication process greatly influences the impurity types and concentrations of the alloys, and therefore greatly dictate which thermal stability mechanisms are active. Mechanically alloyed samples were found to be the most resistant to grain growth. The findings of this research will hopefully guide future efforts to design more thermally stable nanocrystalline alloys. The link between phase stability and grain growth behavior of Ni-W was thoroughly discussed, as well as the dependence of bulk fabrication processing on the contamination found in the alloys. Ultimately, this research has greatly expanded the general understanding of nanocrystalline Ni-W microstructures, and it is likely that similar phenomena occur in other nanocrystalline systems.

  2. High-pressure lattice dynamics and thermodynamic properties of zinc-blende BN from first-principles calculation

    International Nuclear Information System (INIS)

    Wang Huanyou; Xu Hui; Wang Xianchun; Jiang Chunzhi

    2009-01-01

    The density function perturbation theory (DFPT) is employed to study the lattice dynamics and thermodynamic properties (with quasiharmonic approximation) of zinc-blende BN. First we discuss the structural properties and compare the phonon spectrum with available Raman scattering experiments. Thereafter using the calculated phonon dispersions we obtain the PTV equation of state from the free energy. Our results for the above properties are generally speaking in good agreement with experiments and with similar theoretical calculations. Owing to the anharmonic effect at high temperature, the calculated linear thermal expansion coefficients (CTE) are low to experimental data.

  3. Carrying out thermodynamic calculations and definition of the main reactions of decomposition of vapours of ethyl alcohol

    International Nuclear Information System (INIS)

    Sechin, A I; Kyrmakova, O S; Ivanova, T A

    2015-01-01

    Thermodynamic opportunities of course of chemical reactions of decomposition of the vapors of ethyl alcohol necessary at development of devices where these reactions will take place are considered. The entalpiyny method of calculation of constants of balance of probable chemical reactions is given in the Excel editor. Independent reactions of process of oxidation are defined. By result of thermodynamic calculation of each reaction schedules of dependence of a constant of balance on environment temperature from which follows are constructed that one reactions proceed until the end of aside formation of the final products, and others are improbable or impossible. The analysis of the received results shows that reactions of oxidation will successfully proceed in the established directions, and for an intensification of process of decomposition it is necessary to provide a supply of some energy which quantity will be sufficient for oxidation of vapors of ethyl alcohol. Results of calculations showed good convergence with programs of thermodynamic calculations like 'Aster - 4' and 'TERRA'. (paper)

  4. Thermal phase stability of some simulated Defense waste glasses

    International Nuclear Information System (INIS)

    May, R.P.

    1981-04-01

    Three simulated defense waste glass compositions developed by Savannah River Laboratories were studied to determine viscosity and compositional effects on the comparative thermal phase stabilities of these glasses. The glass compositions are similar except that the 411 glasses are high in lithium and low in sodium compared to the 211 glass, and the T glasses are high in iron and low in aluminum compared to the C glass. Specimens of these glasses were heat treated using isothermal anneals as short as 10 min and up to 15 days over the temperature range of 450 0 C to 1100 0 C. Additionally, a specimen of each glass was cooled at a constant cooling rate of 7 0 C/hour from an 1100 0 C melt down to 500 0 C where it was removed from the furnace. The following were observed. The slow cooling rate of 7 0 C/hour is possible as a canister centerline cooling rate for large canisters. Accordingly, it is important to note that a short range diffusion mechanism like cooperative growth phenomena can result in extensive devitrification at lower temperatures and higher yields than a long-range diffusion mechanism can; and can do it without the growth of large crystals that can fracture the glass. Refractory oxides like CeO 2 and (Ni, Mn, Fe) 2 O 4 form very rapidly at higher temperatures than silicates and significant yields can be obtained at sufficiently high temperatures that settling of these dense phases becomes a major microstructural feature during slow cooling of some glasses. These annealing studies further show that below 500 0 C there is but little devitrification occurring implying that glass canisters stored at 300 0 C may be kinetically stable despite not being thermodynamically so

  5. Thermal phase stability of some simulated Defense waste glasses

    Energy Technology Data Exchange (ETDEWEB)

    May, R.P.

    1981-04-01

    Three simulated defense waste glass compositions developed by Savannah River Laboratories were studied to determine viscosity and compositional effects on the comparative thermal phase stabilities of these glasses. The glass compositions are similar except that the 411 glasses are high in lithium and low in sodium compared to the 211 glass, and the T glasses are high in iron and low in aluminum compared to the C glass. Specimens of these glasses were heat treated using isothermal anneals as short as 10 min and up to 15 days over the temperature range of 450/sup 0/C to 1100/sup 0/C. Additionally, a specimen of each glass was cooled at a constant cooling rate of 7/sup 0/C/hour from an 1100/sup 0/C melt down to 500/sup 0/C where it was removed from the furnace. The following were observed. The slow cooling rate of 7/sup 0/C/hour is possible as a canister centerline cooling rate for large canisters. Accordingly, it is important to note that a short range diffusion mechanism like cooperative growth phenomena can result in extensive devitrification at lower temperatures and higher yields than a long-range diffusion mechanism can; and can do it without the growth of large crystals that can fracture the glass. Refractory oxides like CeO/sub 2/ and (Ni, Mn, Fe)/sub 2/O/sub 4/ form very rapidly at higher temperatures than silicates and significant yields can be obtained at sufficiently high temperatures that settling of these dense phases becomes a major microstructural feature during slow cooling of some glasses. These annealing studies further show that below 500/sup 0/C there is but little devitrification occurring implying that glass canisters stored at 300/sup 0/C may be kinetically stable despite not being thermodynamically so.

  6. 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).

  7. A calculational study on neutron kinetics and thermodynamics of a gaseous core fission reactor

    International Nuclear Information System (INIS)

    Kuijper, J.C.

    1992-06-01

    A numerical and analytical study of the static and dynamic properties of a GCFR with oscillating fuel gas (uranium and carbon fluorides) is presented. Neutron kinetics parts of combined GCFR models are introduced. Thermodynamic properties of the GCFR and of the fuel gas are treated. (HP)

  8. HRTEM investigation of phase stability in alumina–zirconia ...

    Indian Academy of Sciences (India)

    tries, at high temperatures, the small diffusion lengths involved can influence the phase stability. The present work ... a function of nanocrystalline size has been shown by Shukla ... and zirconia on a Si(100) single crystal substrate with differ-.

  9. Tethered Nanoparticle–Polymer Composites: Phase Stability and Curvature

    KAUST Repository

    Srivastava, Samanvaya; Agarwal, Praveen; Archer, Lynden A.

    2012-01-01

    different small-angle X-ray scattering signatures in comparison to phase-separated composites comprised of bare or sparsely grafted nanoparticles. A general diagram for the dispersion state and phase stability of polymer tethered nanoparticle-polymer

  10. Phase stability and elastic properties of Cr-V alloys

    Science.gov (United States)

    Gao, M. C.; Suzuki, Y.; Schweiger, H.; Doǧan, Ö. N.; Hawk, J.; Widom, M.

    2013-02-01

    V is the only element in the periodic table that forms a complete solid solution with Cr and thus is particularly important in alloying strategy to ductilize Cr. This study combines first-principles density functional theory calculations and experiments to investigate the phase stability and elastic properties of Cr-V binary alloys. The cluster expansion study reveals the formation of various ordered compounds at low temperatures that were not previously known. These compounds become unstable due to the configurational entropy of bcc solid solution as the temperature is increased. The elastic constants of ordered and disordered compounds are calculated at both T = 0 K and finite temperatures. The overall trends in elastic properties are in agreement with measurements using the resonant ultrasound spectroscopy method. The calculations predict that addition of V to Cr decreases both the bulk modulus and the shear modulus, and enhances the Poisson’s ratio, in agreement with experiments. Decrease in the bulk modulus is correlated to decrease in the valence electron density and increase in the lattice constant. An enhanced Poisson’s ratio for bcc Cr-V alloys (compared to pure Cr) is associated with an increased density of states at the Fermi level. Furthermore, the difference charge density in the bonding region in the (110) slip plane is highest for pure Cr and decreases gradually as V is added. The present calculation also predicts a negative Cauchy pressure for pure Cr, and it becomes positive upon alloying with V. The intrinsic ductilizing effect from V may contribute, at least partially, to the experimentally observed ductilizing phenomenon in the literature.

  11. Phase stability and elastic properties of Cr-V alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gao, M C; Suzuki, Y; Schweiger, H; Doğan, Ö N; Hawk, J; Widom, M

    2013-01-23

    V is the only element in the periodic table that forms a complete solid solution with Cr and thus is particularly important in alloying strategy to ductilize Cr. This study combines first-principles density functional theory calculations and experiments to investigate the phase stability and elastic properties of Cr–V binary alloys. The cluster expansion study reveals the formation of various ordered compounds at low temperatures that were not previously known. These compounds become unstable due to the configurational entropy of bcc solid solution as the temperature is increased. The elastic constants of ordered and disordered compounds are calculated at both T = 0 K and finite temperatures. The overall trends in elastic properties are in agreement with measurements using the resonant ultrasound spectroscopy method. The calculations predict that addition of V to Cr decreases both the bulk modulus and the shear modulus, and enhances the Poisson’s ratio, in agreement with experiments. Decrease in the bulk modulus is correlated to decrease in the valence electron density and increase in the lattice constant. An enhanced Poisson’s ratio for bcc Cr–V alloys (compared to pure Cr) is associated with an increased density of states at the Fermi level. Furthermore, the difference charge density in the bonding region in the (110) slip plane is highest for pure Cr and decreases gradually as V is added. The present calculation also predicts a negative Cauchy pressure for pure Cr, and it becomes positive upon alloying with V. The intrinsic ductilizing effect from V may contribute, at least partially, to the experimentally observed ductilizing phenomenon in the literature.

  12. Phase stability of transition metals and alloys

    International Nuclear Information System (INIS)

    Hixson, R.S.; Schiferl, D.; Wills, J.M.; Hill, M.A.

    1997-01-01

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). This project was focused on resolving unexplained differences in calculated and measured phase transition pressures in transition metals. Part of the approach was to do new, higher accuracy calculations of transmission pressures for group 4B and group 6B metals. Theory indicates that the transition pressures for these baseline metals should change if alloyed with a d-electron donor metal, and calculations done using the Local Density Approximation (LDA) and the Virtual Crystal Approximation (VCA) indicate that this is true. Alloy systems were calculated for Ti, Zr and Hf based alloys with various solute concentrations. The second part of the program was to do new Diamond Anvil Cell (DAC) measurements to experimentally verify calculational results. Alloys were prepared for these systems with grain size suitable for Diamond Anvil Cell experiments. Experiments were done on pure Ti as well as Ti-V and Ti-Ta alloys. Measuring unambiguous transition pressures for these systems proved difficult, but a new technique developed yielded good results

  13. Electronic structure and phase stability during martensitic transformation in Al-doped ZrCu intermetallics

    International Nuclear Information System (INIS)

    Qiu Feng; Shen Ping; Liu Tao; Lin Qiaoli; Jiang Qichuan

    2010-01-01

    Martensitic transformation, phase stability and electronic structure of Al-doped ZrCu intermetallics were investigated by experiments and first-principles calculations using the pseudopotentials plane wave method. The formation energy calculations indicate that the stability of the ZrCu phase increases with the increasing Al content. Al plays a decisive role in controlling the formation and microstructures of the martensite phases in Zr-Cu-Al alloys. The total energy difference between ZrCu (B2) austenite and ZrCu martensite plays an important role in the martensitic transformation. The phase stability is dependent on its electronic structure. The densities of states (DOS) of the intermetallics were discussed in detail.

  14. Experimental investigation and thermodynamic calculation of the Fe-Mg-Mn and Fe-Mg-Ni systems

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Peisheng; Zhao, Jingrui; Xu, Honghui; Liu, Shuhong; Ouyang, Hongwu [Central South Univ., Hunan (China). State Key Lab. of Powder Metallurgy; Du, Yong [Central South Univ., Hunan (China). State Key Lab. of Powder Metallurgy; Harbin Institute of Technology (China). State Key Lab. of Advanced Welding Production Technology; Gang, Tie; Fen, Jicai [Harbin Institute of Technology (China). State Key Lab. of Advanced Welding Production Technology; Zhang, Lijun [Central South Univ., Hunan (China). State Key Lab. of Powder Metallurgy; Bochum Univ. (Germany). ICAMS Inst.; He, Cuiyun [Guangxi Univ. (China). College of Physical Science and Technology

    2011-01-15

    Based on the thermodynamic calculations extrapolated from the corresponding binary sub-systems, four decisive alloys in the Fe-Mg-Mn system and three in the Fe-Mg-Ni system were selected and prepared using a powder metallurgy method to measure the isothermal sections at 500 C in both systems. The prepared samples were annealed at 500 C, and then subjected to X-ray diffraction, optical microscopy, scanning electron microscopy with energy-dispersive X-ray spectrometry as well as electron probe microanalysis. Taking into account the presently obtained experimental data and the experimental data available in the literature, thermodynamic modeling was performed for the above systems. It was found that a direct extrapolation from the corresponding three binary systems can well reproduce all the experimental data in the Fe-Mg-Mn system, while two thermodynamic parameters are needed in the Fe-Mg-Ni system to fit all the experimental data. The liquidus projections and reaction schemes for the Fe-Mg-Mn and Fe-Mg-Ni systems are also presented. (orig.)

  15. Magnetic materials at finite temperatures: thermodynamics and combined spin and molecular dynamics derived from first principles calculations

    International Nuclear Information System (INIS)

    Eisenbach, Markus; Perera, Meewanage Dilina N.; Landau, David P; Nicholson, Don M.; Yin, Junqi; Brown, Greg

    2015-01-01

    We present a unified approach to describe the combined behavior of the atomic and magnetic degrees of freedom in magnetic materials. Using Monte Carlo simulations directly combined with first principles the Curie temperature can be obtained ab initio in good agreement with experimental values. The large scale constrained first principles calculations have been used to construct effective potentials for both the atomic and magnetic degrees of freedom that allow the unified study of influence of phonon-magnon coupling on the thermodynamics and dynamics of magnetic systems. The MC calculations predict the specific heat of iron in near perfect agreement with experimental results from 300K to above Tc and allow the identification of the importance of the magnon-phonon interaction at the phase-transition. Further Molecular Dynamics and Spin Dynamics calculations elucidate the dynamics of this coupling and open the potential for quantitative and predictive descriptions of dynamic structure factors in magnetic materials using first principles-derived simulations.

  16. A thermodynamic data base for Tc to calculate equilibrium solubilities at temperatures up to 300 deg C

    International Nuclear Information System (INIS)

    Puigdomenech, I.; Bruno, J.

    1995-04-01

    Thermodynamic data has been selected for solids and aqueous species of technetium. Equilibrium constants have been calculated in the temperature range 0 to 300 deg C at a pressure of 1 bar for T r Cdeg pm values for mononuclear hydrolysis reactions. The formation constants for chloro complexes of Tc(V) and Tc(IV), whose existence is well established, have been estimated. The majority of entropy and heat capacity values in the data base have also been estimated, and therefore temperature extrapolations are largely based on estimations. The uncertainties derived from these calculations are described. Using the data base developed in this work, technetium solubilities have been calculated as a function of temperature for different chemical conditions. The implications for the mobility of Tc under nuclear repository conditions are discussed. 70 refs

  17. Investigation and thermodynamic calculation of phase diagram of CdI2-PbI2-NaI system

    International Nuclear Information System (INIS)

    Storonkin, A.V.; Vasil'kova, I.V.; Korobkov, S.V.

    1976-01-01

    Using the thermographic and X-ray phase analyses binary CdI 2 -PbI 2 , PI 2 -NaI, CdI 2 -NaI systems and a triple CdI 2 -PbI 2 -NaI system are investigated and their melting diagrams are plotted. A method of thermodynamic calculation has been proposed and tested of the shape of the eutectic lines for the system CdI 2 -PbI 2 -NaI, taking into account the non-ideality of the liquid phase. The method uses data obtained for the binary systems. The liquidus surface of the triple system has been constructed on the basis of the calculation. The results of the calculation of the triple eutectics are in good agreement with the experimental data

  18. Phase stability, elasticity, and theoretical strength of polonium from first principles

    Czech Academy of Sciences Publication Activity Database

    Legut, Dominik; Friák, Martin; Šob, Mojmír

    2010-01-01

    Roč. 81, č. 21 (2010), 214118/1/-214118/19/ ISSN 1098-0121 R&D Projects: GA AV ČR IAA100100920; GA MŠk(CZ) OC10008 Institutional research plan: CEZ:AV0Z20410507 Keywords : polonium * phase stability * elasticity * theoretical strength * ab initio calculations Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.772, year: 2010

  19. Glass forming ability of the Fe-Zr-Cu system studied by thermodynamic calculation and ion beam mixing

    International Nuclear Information System (INIS)

    Wang, T.L.; Liu, B.X.

    2009-01-01

    The glass forming ability/range (GFA/GFR) of the Fe-Zr-Cu system was studied by thermodynamic calculation based on Miedema's model and Alonso's method. It is found that when the atomic concentration of Zr is between 34% and 56%, no matter what the atomic concentrations of Fe and Cu are, amorphous phase could be obtained, thus the atomic mismatch playing a dominating role in influencing the GFA. While the atomic concentration of Zr is out of the above range, the GFA is highly influenced by the immiscibility between Fe and Cu. Experimentally, ion beam mixing was carried out to synthesize amorphous alloys in the Fe-Zr-Cu system. It turned out that in the samples with overall compositions of Fe 26 Zr 36 Cu 38 , Fe 52 Zr 27 Cu 21 and Fe 21 Zr 60 Cu 19 , which are located in or at the edge of the calculated GFR, amorphous phases were indeed obtained, whereas no amorphous phase was obtained if the overall compositions were located outside of the predicted region favoring for amorphous alloy formation, showing a good agreement between the experimental results and the thermodynamic calculation.

  20. Effect of Cu Alloying on S Poisoning of Ni Surfaces and Nanoparticle Morphologies Using Ab-Initio Thermodynamics Calculations.

    Science.gov (United States)

    Kim, Ji-Su; Kim, Byung-Kook; Kim, Yeong-Cheol

    2015-10-01

    We investigated the effect of Cu alloying on S poisoning of Ni surfaces and nanoparticle morphologies using ab-initio thermodynamics calculations. Based on the Cu segregation energy and the S adsorption energy, the surface energy and nanoparticle morphology of pure Ni, pure Cu, and NiCu alloys were evaluated as functions of the chemical potential of S and the surface orientations of (100), (110), and (111). The constructed nanoparticle morphology was varied as a function of chemical potential of S. We find that the Cu added to Ni for NiCu alloys is strongly segregated into the top surface, and increases the S tolerance of the NiCu nanoparticles.

  1. Calculations of the thermal expansion, cohesive energy and thermodynamic stability of a Van der Waals crystal - fullerene C60

    International Nuclear Information System (INIS)

    Zubov, V.I.; Tretiakov, N.P.; Teixeira Rabelo, J.N.; Sanchez Ortiz, J.F.

    1994-01-01

    The temperature dependence of the intermolecular distance and the cohesive energy in the high-temperature modification of C 60 solid fullerene was studied on basis of the correlative method of unsymmetrized self-consistent field. The central intermolecular potential of Girifalco and its approximation by Yakub were used. We conclude about the decisive role of anharmonic effects at high temperatures. The discrepancy between the calculated and experimental values of intermolecular distance does not exceed 0.8% on the whole temperature interval. The temperature of loss of thermodynamic stability was obtained (∼1915 K) and a possible melting temperature was estimated (∼1400 K). ((orig.))

  2. ASTEM, Evaluation of Gibbs, Helmholtz and Saturation Line Function for Thermodynamics Calculation

    International Nuclear Information System (INIS)

    Moore, K.V.; Burgess, M.P.; Fuller, G.L.; Kaiser, A.H.; Jaeger, D.L.

    1974-01-01

    1 - Description of problem or function: ASTEM is a modular set of FORTRAN IV subroutines to evaluate the Gibbs, Helmholtz, and saturation line functions as published by the American Society of Mechanical Engineers (1967). Any thermodynamic quantity including derivative properties can be obtained from these routines by a user-supplied main program. PROPS is an auxiliary routine available for the IBM360 version which makes it easier to apply the ASTEM routines to power station models. 2 - Restrictions on the complexity of the problem: Unless re-dimensioned by the user, the highest derivative allowed is order 9. All arrays within ASTEM are one-dimensional to save storage area

  3. Experimental investigation and thermodynamic calculation of the Zn–Fe–Ce system

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Longfei; Wu, Changjun [Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou University, Jiangsu 213164 (China); Jiangsu Collaborative Innovation Center of Photovolatic Science and Engineering, Changzhou University, Jiangsu 213164 (China); Wang, Jianhua, E-mail: wangjh@cczu.edu.cn [Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou University, Jiangsu 213164 (China); Jiangsu Collaborative Innovation Center of Photovolatic Science and Engineering, Changzhou University, Jiangsu 213164 (China); Liu, Ya; Tu, Hao; Su, Xuping [Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou University, Jiangsu 213164 (China); Jiangsu Collaborative Innovation Center of Photovolatic Science and Engineering, Changzhou University, Jiangsu 213164 (China)

    2015-11-05

    The 450 °C and 600 °C isothermal sections of the Zn–Fe–Ce system were investigated using equilibrated alloys and diffusion couples. The samples were analyzed by Scanning Electron Microscopy equipped with Energy Dispersive X-ray Spectrometer analysis and X-ray power diffraction. 15 and 13 three-phase regions were identified to exist at 450 °C and 600 °C, respectively. No ternary compound was found. Ce can not dissolve into all the Zn–Fe binary compounds and the solubilities of Fe in all the Zn–Ce binary phases were limited. All the Zn–Fe compounds can equilibrate with CeZn{sub 11} and all the Ce–Zn compounds (except CeZn) can equilibrate with α-Fe. Furthermore, thermodynamic extrapolation of the Zn–Fe–Ce system was carried out and showed good agreement well with detected phase relationships. - Highlights: • 450 °C and 600 °C sections of the Zn–Fe–Ce system were constructed. • No ternary compound exists. • Ce can not dissolve into all the Zn–Fe compounds. • All the Fe–Zn compounds can equilibrate with CeZn{sub 11}. • Thermodynamic extrapolation results agree with experimental data.

  4. Thermodynamic modeling of the Co–Hf system supported by key experiments and first-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Xingxu [School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083 (China); State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Liu, Shuhong, E-mail: shhliu@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Sino-German Cooperation Group “Microstructure in Al alloys”, Central South University, Changsha, Hunan 410083 (China); Cheng, Kaiming; Tang, Ying [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Ou, Pengfei [School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083 (China); State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Nash, Philip [Thermal Processing Technology Center, Illinois Institute of Technology (IIT), 10 West 32nd Street, Chicago, IL 60616 (United States); Sundman, Bo [INSTN, CEA Saclay, 91191 Gif-Sur-Yvette Cedex (France); Du, Yong [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Sino-German Cooperation Group “Microstructure in Al alloys”, Central South University, Changsha, Hunan 410083 (China); Zheng, Feng [School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083 (China)

    2015-05-20

    Highlights: • Heat contents of Co{sub 2}Hf and CoHf{sub 2} were measured by drop calorimetry. • Enthalpy of formation for Co{sub 23}Hf{sub 6} was computed via first-principles calculations. • Co–Hf system was assessed by means of CALPHAD approach. • Order–disorder model is used to describe B2 (CoHf) and A2 (βHf). • Glass forming range of the Co–Hf amorphous alloys was predicted. - Abstract: Phase equilibria and thermodynamic properties of the Co–Hf system were investigated via calorimetric measurements, first-principles calculations and thermodynamic modeling. Heat contents of Co{sub 2}Hf and CoHf{sub 2} were measured by drop calorimetry from 300 to 1200 °C. The enthalpy of formation for Co{sub 23}Hf{sub 6} at 0 K was computed via first-principles calculations. Based on the experimental measurements and first-principles calculations from the present work and the literature, the Co–Hf system was assessed by means of CALPHAD (CALculation of PHAse Diagram) approach. The excess Gibbs energy of solution phases was modeled with Redlich–Kister polynomial. Sublattice models were employed to describe the homogeneity ranges of Co{sub 2}Hf, CoHf and CoHf{sub 2}. The order–disorder transition between B2 (CoHf) and A2 (βHf) phases was taken into account in the current optimization. Using the optimized parameters, glass forming range (GFR) of the Co–Hf amorphous alloys was predicted to be 15–75 at.% Hf, which is in satisfactory agreement with the experimental observation.

  5. First-principles calculation on the thermodynamic and elastic properties of precipitations in Al-Cu alloys

    Science.gov (United States)

    Sun, Dongqiang; Wang, Yongxin; Zhang, Xinyi; Zhang, Minyu; Niu, Yanfei

    2016-12-01

    First-principles calculations based on density functional theory was used to investigate the structural, thermodynamic and elastic properties of precipitations, θ″, θ‧ and θ, in Al-Cu alloys. The values of lattice constants accord with experimental results well. The structural stability of θ is the best, followed by θ‧ and θ″. In addition, due to the highest bulk modulus, shear modulus and Young's modulus, θ possesses the best reinforcement effect in precipitation hardening process considered only from mechanical properties of perfect crystal. According to the values of B/G, Poisson's ratio and C11-C12, θ‧ has the worst ductility, while θ″ has the best ductility, the ductility of θ is in the middle. The ideal tensile strength of θ″, θ‧ and θ calculated along [100] and [001] directions are 20.87 GPa, 23.11 GPa and 24.70 GPa respectively. The analysis of electronic structure suggests that three precipitations all exhibit metallic character, and number of bonding electrons and bonding strength are the nature of different thermodynamic and elastic properties for θ″, θ‧ and θ.

  6. First-Principle Calculations for Elastic and Thermodynamic Properties of Diamond

    International Nuclear Information System (INIS)

    Fu Zhijian; Chen Xiangrong; Gou Qingquan; Ji Guangfu

    2009-01-01

    The elastic constants and thermodynamic properties of diamond are investigated by using the CRYSTAL03 program. The lattice parameters, the bulk modulus, the heat capacity, the Grueneisen parameter, and the Debye temperature are obtained. The results are in good agreement with the available experimental and theoretical data. Moreover, the relationship between V/V 0 and pressure, the elastic constants under high pressure are successfully obtained. Especially, the elastic constants of diamond under high pressure are firstly obtained theoretically. At the same time, the variations of the thermal expansion α with pressure P and temperature Tare obtained systematically in the ranges of 0-870 GPa and 0-1600 K. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  7. Thermodynamic Calculations of Hydrogen-Oxygen Detonation Parameters for Various Initial Pressures

    Science.gov (United States)

    Bollinger, Loren E.; Edse, Rudolph

    1961-01-01

    Composition, temperature, pressure and density behind a stable detonation wave and its propagation rate have been calculated for seven hydrogen-oxygen mixture at 1, 5, 25 and 100 atm initial pressure, and at an initial temperature of 40C. For stoichiometric mixtures that calculations also include an initial temperature of 200C. According to these calculations the detonation velocities of hydrogen-oxygen mixtures increase with increasing initial pressure, but decrease slightly when the initial temperature is raised from 40 to 200 C. The calculated detonation velocities agree satisfactorily with values determined experimentally. These values will be published in the near future.

  8. Prediction of thermodynamic properties of solute elements in Si solutions using first-principles calculations

    International Nuclear Information System (INIS)

    Iwata, K.; Matsumiya, T.; Sawada, H.; Kawakami, K.

    2003-01-01

    The method is presented to predict the activity coefficients and the interaction parameters of the solute elements in infinite dilute Si solutions by the use of first-principles calculations based on density functional theory. In this method, the regular solution model is assumed. The calculated activity coefficients in solid Si are converted to those in molten Si by the use of the solid-liquid partition coefficients. Furthermore, the interaction parameters in solid Si solutions are calculated and compared with reported experimental values of those in liquid Si solutions. The results show that the calculated activity coefficients and interaction parameters of Al, Fe, Ti and Pb in Si solutions are in good agreement with the tendency of the experiments. However, the calculations have some quantitative discrepancy from the experiments. It is expected that consideration of the excess entropy would reduce this discrepancy

  9. TEMPERATURE INFLUENCE ON PHASE STABILITY OF ETHANOL-GASOLINE MIXTURES

    Directory of Open Access Journals (Sweden)

    Valerian Cerempei

    2011-06-01

    Full Text Available The article investigates phase stability of ethanol-gasoline mixtures depending on their composition, water concentration in ethanol and ethanol-gasoline mixture and temperature. There have been determined the perfect functioning conditions of spark ignition engines fueled with ethanol-gasoline mixtures.

  10. Phase stability of silver particles embedded calcium phosphate ...

    Indian Academy of Sciences (India)

    Abstract. In this paper, we report the compositional variation-dependent phase stability of hydroxyapatite ... material along with other calcium phosphate bioceramics.3–5 ... Model U-3310). ... recorded using a Field Emissio scanning electron microscope .... the colour change of the silver-doped samples only after sin-.

  11. Thermodynamic calculations for chemical vapor deposition of silicon carbide using ethyltrichlorosilane

    International Nuclear Information System (INIS)

    Nakano, Junichi; Yamada, Reiji

    1995-06-01

    The computer code SOLGASMIX-PV, which is based on the free energy minimization method, was used to calculate the equilibrium composition of the C 2 H 5 SiCl 3 -H 2 -Ar system. In the C 2 H 5 SiCl 3 -H 2 system, the calculation results showed that β-SiC+C, β-SiC, β-SiC+Si(1), Si(1), β-SiC+Si(s), and Si(s) would be deposited, whereas β-SiC+C and C would be deposited in the C 2 H 5 SiCl 3 -Ar system. By comparing the calculated results with the experimental results from the literature, in the region calculated as β-SiC+C to be deposited, β-SiC+C, β-SiC, or β-SiC+Si(s) was deposited in the experiments. The calculations revealed that the gas mole ratios for CVD were optimum when the (Ar+H 2 )/C 2 H 5 SiCl 3 took a value between 1000 and 10000, and the Ar/H 2 between 0.43 and 1.5. The deposition temperature was optimum between 1100-1500K. In this region, the Si atoms were most effectively used as source materials, and formed a single phase of β-SiC on the substrate. (author)

  12. Calculation for the thermodynamic properties of an alternative refrigerant (R508b) using artificial neural network

    International Nuclear Information System (INIS)

    Soezen, Adnan; Ozalp, Mehmet; Arcaklioglu, Erol

    2007-01-01

    This study proposes a alternative approach based on artificial neural networks (ANNs) to determine the thermodynamic properties - specific volume, enthalpy and entropy - of an alternative refrigerant (R508b) for both saturated liquid-vapor region (wet vapor) and superheated vapor region. In the ANN, the back-propagation learning algorithm with two different variants, namely scaled conjugate gradient (SCG) and Levenberg-Marquardt (LM), and Logistic Sigmoid transfer function were used to determine the best approach. The most suitable algorithm and with appropriate number of neurons (i.e. 7) in the hidden layer is found to be the LM algorithm which has provided the minimum error. For wet vapor region, R 2 values - which are errors known as absolute fraction of variance - are 0.983495, 0.969027, 0.999984, 0.999963, 0.999981, and 0.999975, for specific volume, enthalpy and entropy for training and testing, respectively. Similarly, for superheated vapor, they are: 0.995346, 0.996947, 0.999996, 0.999997, 0.999974, and 0.999975, for training and testing, respectively. According to the regression analysis results, R 2 values are 0.9312, 0.9708, 0.9428, 0.9343, 0.967 and 0.9546 for specific volume, enthalpy and entropy for wet vapor region and superheated vapor, respectively. The comparisons of the results suggest that, ANN provided results comfortably within the acceptable range. This study, deals with the potential application of the ANNs to represent PVTx (pressure-specific volume-temperature-vapor quality) data. Therefore, reducing the risk of experimental uncertainties and also removing the need for complex analytic equations requiring long computational time and efforts

  13. Monte Carlo calculations of thermodynamic properties of deuterium under high pressures

    International Nuclear Information System (INIS)

    Levashov, P R; Filinov, V S; BoTan, A; Fortov, V E; Bonitz, M

    2008-01-01

    Two different numerical approaches have been applied for calculations of shock Hugoniots and compression isentrope of deuterium: direct path integral Monte Carlo and reactive Monte Carlo. The results show good agreement between two methods at intermediate pressure which is an indication of correct accounting of dissociation effects in the direct path integral Monte Carlo method. Experimental data on both shock and quasi-isentropic compression of deuterium are well described by calculations. Thus dissociation of deuterium molecules in these experiments together with interparticle interaction play significant role

  14. Calculation of the phonon density of states and related thermodynamic properties for trigonal selenium

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Alldredge, G. P.; McMurry, H. L.

    1983-01-01

    The phonon density of states for trigonal selenium has been calculated on the basis of a short range force model giving good overall agreement with experimental room temperature phonon dispersion data. A qualitative comparison with an experimental determination of the phonon density of states shows...... similarities in the gross features, but the experimental data lacks many of the finer details shown by the theoretical results due to resolution effects. The lattice dynamical contribution to the heat capacity CV is calculated and is found to be in good agreement with experimental determinations of Cp after...

  15. Calculation of thermodynamic equilibrium between bcc disordered solid solutions U and Mo

    International Nuclear Information System (INIS)

    Alonso, Paula R.; Rubiolo, Gerardo H.

    2003-01-01

    There is actually an interest to develop a new fuel with higher density for research reactors. Fuel plates would be obtained by dispersion, a method that requires both a very dense fuel dispersant (>15.0 g U/cm 3 ) and a very high volume loading of the dispersant (>55%). Dispersants based in gamma (BCC) stabilized uranium alloys are being investigated, as they are able to reach uranium densities of 17.0 g U/cm 3 . Among them, we focus in U(Mo) bcc solid solutions with the addition of ternary elements to stabilize gamma phase. Transition metals, 4d and 5d, of groups VII and VIII are good candidates for the ternary alloy U - Mo - X. Their relative power to stabilize gamma phase seems to be in close relation with bonding energies between atoms in the alloy. A first approach to the calculation of these energies has been performed by the semi empiric method of Miedema where only bonds between pairs are considered, neglecting ternary and quaternary bonds. There is also a lack of information concerning solubilities of the ternary elements in the ternary cubic phase. In this work we aim to calculate bonding energies between atoms in the alloy using a cluster expansion of the formation energy (T=0 K) of a series of bcc ordered compounds in the systems U-Mo-X. Then the calculation of the equilibrium phase diagram by the Cluster Variation Method will be done (CVM). We show here the first part of the investigation devoted to calculation of phases equilibria in the U Mo system Formation energies of the ordered compounds were obtained by the first principles methods TB-LMTO-ASA and FP-LAPW. Another set of bonding energies was calculated in order to fit the known experimental diagram and new formation energies for the ordered compounds were derived from them. Discrepancies between both sets are discussed. (author)

  16. 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)

  17. Evaluation of the Precipitation Behavior in SA508 Gr. 4N Low Alloy Steel Using a Thermodynamic Calculation

    International Nuclear Information System (INIS)

    Park, Sang Gyu; Wee, Dang Moon; Kim, Min Chul; Lee, Bong Sang

    2007-01-01

    Low carbon low alloy steels, used as nuclear pressure vessels, steam generators and so on, hold a large portion of materials for nuclear power plants, and they are very important materials since they determine the safety and the life span of nuclear power plants. In addition, they are utilized for a long period under very severe conditions such as a high pressure, high temperature, neutron irradiation and corrosion, so they need a good combination of strength and toughness, a good weldability and an excellent neutron irradiation resistance and so on. SA508 Gr.3 steel shows the upper bainite microstructure, which is a less tough, so the steel is more difficult to obtain good toughness than to have good strength. And then, if a loss of toughness due to a neutron irradiation during service is considered, above all improving the toughness is important when a pressure vessel is fabricated It is known that a higher strength and fracture toughness of low alloy steels could be achieved by increasing the Ni and Cr contents. In this study, we have performed a thermodynamic calculation based on the microstructure of SA508 Gr.4N low alloy steel which has higher Ni and Cr contents than SA508 Gr.3 low alloy steel. Based on the microstructure/property relations obtained from literature research experimental works on SA508 Gr.4N steels, and by predicting the constitutional changes with alloying elements (such as Mn, Cr) during individual steps of a steel making process a using thermodynamic calculation, fundamental information for an alloy design have been discussed

  18. Thermodynamic study of complexation of thorium with pyridine monocarboxylates by calorimetry and DFT calculations

    International Nuclear Information System (INIS)

    Rama Mohana Rao, D.; Rawat, Neetika; Sawant, R.M.; Tomar, B.S.; Manna, D.; Ghanty, T.K.

    2013-01-01

    Stability constants of Th(IV) complexes with pyridine mono-carboxylates, namely, picolinate, nicotinate and isonicotinate have been determined following potentiometric titration of the metal ion and ligand mixtures with NaOH solution of known concentration. These data were used during the analysis of the calorimetric titration data to obtain the enthalpy of complexation reactions. The experimental data have been compared with that obtained from the DFT based theoretical calculations. (author)

  19. The effect of hydroxyl groups on the stability and thermodynamic properties of polyhydroxylated xanthones as calculated by density functional theory

    International Nuclear Information System (INIS)

    Qu, Ruijuan; Liu, Hongxia; Zhang, Qi; Flamm, Alison; Yang, Xi; Wang, Zunyao

    2012-01-01

    Highlights: ► The strength of the hydrogen bonds existed in PHOXTHs is ascertained. ► Good linear relations exist between the thermodynamic properties and N PHOS . ► The relative stability order of PHOXTH congeners is theoretically proposed. ► There is a good relation between C p,m and the temperature. - Abstract: There are three types of intramolecular hydrogen bonds with bond energy about 52 kJ mol −1 , 12 kJ mol −1 , 20 kJ mol −1 , respectively in PHOXTHs which were determined by computation on B3LYP/6-311G** level. The internal rotational potentials of the hydroxy group of 1-MHOXTH and 4′-MHOXTH are evaluated, and the influences of the spatial orientation of the hydroxy groups on the intramolecular hydrogen bonds and molecular stability are illustrated. The standard enthalpy of formation (Δ f H θ ) and standard Gibbs energy of formation (Δ f G θ ) for the most stable conformation of 135 PHOXTHs are calculated by the combination of Gaussian 03 and isodesmic reactions and the theoretical order of relative stability is proposed according to the relative magnitude of calculated Δ f G θ values. In addition, the values of molar heat capacities at constant pressure (C p,m ) from 200 to 1000 K for PHOXTH congeners are calculated.

  20. Computational study of the hydrolysis of carbonyl sulphide: Thermodynamics and kinetic constants estimation using ab initio calculations

    International Nuclear Information System (INIS)

    Vidal-Vidal, Á.; Pérez-Rodríguez, M.; Piñeiro, M.M.

    2017-01-01

    Highlights: • OCS hydrolysis equilibrium constants were calculated using QM composite methods. • CBS-QB3 was found to be the most adequate method for OCS thermodynamic calculations. • Calculated hydrolysis yields decrease when temperature increases. • The isotopic effect is less significant than temperature or initial concentration dependences. - Abstract: Carbonyl sulphide is the predominant sulphur compound in the atmosphere, contributing to the formation of aerosol particles affecting global climate. Human activity has significantly increased its total amount since the beginning of the Industrial Revolution due to its presence in petroleum and coal, reason why it is necessary to understand and control its emissions. On the other hand, carbonyl sulphide is an undesired substance for catalysis in important industrial processes. Hydrolysis is the most promising among the different strategies to reduce its presence, giving as products carbon dioxide and hydrogen sulphide. In the present work, the mechanism of reaction of carbonyl sulphide hydrolysis process in gas phase was studied from 400 K to 1500 K, equilibrium constants were obtained and reaction yields were estimated, by means of composite quantum-computational methods. Good agreement with literature experimental results confirms the suitability of the chosen methods, specially CBS-QB3, in supporting the reaction mechanism, giving accurate equilibrium constant values, and obtaining realistic yields. The effect of isotopic substitution in OCS was also studied, from 300 K to 1500 K, being much less significant than temperature dependence.

  1. A thermodynamic data base for Tc to calculate equilibrium solubilities at temperatures up to 300 deg C

    Energy Technology Data Exchange (ETDEWEB)

    Puigdomenech, I [Studsvik AB, Nykoeping (Sweden); Bruno, J [Intera Information Technologies SL, Cerdanyola (Spain)

    1995-04-01

    Thermodynamic data has been selected for solids and aqueous species of technetium. Equilibrium constants have been calculated in the temperature range 0 to 300 deg C at a pressure of 1 bar for T<100 deg C and at the steam saturated pressure at higher temperatures. For aqueous species, the revised Helgeson-Kirkham-Flowers model is used for temperature extrapolations. The data base contains a large amount of estimated data, and the methods used for these estimations are described in detail. A new equation is presented that allows the estimation of {Delta}{sub r}Cdeg{sub pm} values for mononuclear hydrolysis reactions. The formation constants for chloro complexes of Tc(V) and Tc(IV), whose existence is well established, have been estimated. The majority of entropy and heat capacity values in the data base have also been estimated, and therefore temperature extrapolations are largely based on estimations. The uncertainties derived from these calculations are described. Using the data base developed in this work, technetium solubilities have been calculated as a function of temperature for different chemical conditions. The implications for the mobility of Tc under nuclear repository conditions are discussed. 70 refs.

  2. Iron -chromium alloys and free surfaces: from ab initio calculations to thermodynamic modeling

    International Nuclear Information System (INIS)

    Levesque, M.

    2010-11-01

    Ferritic steels possibly strengthened by oxide dispersion are candidates as structural materials for generation IV and fusion nuclear reactors. Their use is limited by incomplete knowledge of the iron-chromium phase diagram at low temperatures and of the phenomena inducing preferential segregation of one element at grain boundaries or at surfaces. In this context, this work contributes to the multi-scale study of the model iron-chromium alloy and their free surfaces by numerical simulations. This study begins with ab initio calculations of properties related to the mixture of atoms of iron and chromium. We highlight complex dependency of the magnetic moments of the chromium atoms on their local chemical environment. Surface properties are also proving sensitive to magnetism. This is the case of impurity segregation of chromium in iron and of their interactions near the surface. In a second step, we construct a simple energy model for high numerical efficiency. It is based on pair interactions on a rigid lattice to which are given local chemical environment and temperature dependencies. With this model, we reproduce the ab initio results at zero temperature and experimental results at high temperature. We also deduce the solubility limits at all intermediate temperatures with mean field approximations that we compare to Monte Carlo simulations. The last step of our work is to introduce free surfaces in our model. We then study the effect of ab initio calculated bulk and surface properties on surface segregation.Finally, we calculate segregation isotherms. We therefore propose an evolution model of surface composition of iron-chromium alloys as a function of bulk composition. which are given local chemical environment and temperature dependencies. With this model, we reproduce the ab initio results at zero temperature and experimental results at high temperature. We also deduce the solubility limits at all intermediate temperatures with mean field approximations that

  3. 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

  4. 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.

  5. Use of thermodynamic calculation to predict the effect of Si on the ageing behavior of Al-Mg-Si-Cu alloys

    International Nuclear Information System (INIS)

    Ji, Yanli; Zhong, Hao; Hu, Ping; Guo, Fuan

    2011-01-01

    Research highlights: → Thermodynamic calculation can predict the ageing behavior of 6xxx alloys. → The hardness level of the alloys depends on the Si content in as-quenched matrix. → The precipitation strengthening effect depends on the Mg 2 Si level of the alloys. -- Abstract: Thermodynamic calculation was employed to predict the influence of Si content on the ageing behavior of Al-Mg-Si-Cu alloys. In addition, experiments were carried out to verify the predictions. The results show that thermodynamic calculation can predict the effect of Si content on the ageing behavior of the studied alloys. This study further proposes that the hardness level of alloys during ageing is directly related to the Si content in the as-quenched supersaturated solution, while the precipitation strengthening effect is directly related to the Mg 2 Si level of the alloys.

  6. Calculation of thermodynamic functions of aluminum plasma for high-energy-density systems

    International Nuclear Information System (INIS)

    Shumaev, V. V.

    2016-01-01

    The results of calculating the degree of ionization, the pressure, and the specific internal energy of aluminum plasma in a wide temperature range are presented. The TERMAG computational code based on the Thomas–Fermi model was used at temperatures T > 105 K, and the ionization equilibrium model (Saha model) was applied at lower temperatures. Quantitatively similar results were obtained in the temperature range where both models are applicable. This suggests that the obtained data may be joined to produce a wide-range equation of state.

  7. First-principles thermodynamic calculations of diffusion characteristics of impurities in γ-iron

    International Nuclear Information System (INIS)

    Tsuru, T.; Kaji, Y.

    2013-01-01

    Because solute impurities have an effect on embrittlement through segregation under irradiation, solute stability and the influence of irradiation on the diffusion characteristics of impurities become prominent due to several acceleration effects of high irradiance circumstances in irradiated materials. In this study, the diffusion characteristics of several impurities in non-magnetic fcc iron are investigated using first-principles density functional theory (DFT) calculations. In accordance with classical diffusion and transition state theories, we nonempirically evaluated the contribution to properties of the binding energy between vacancy and each impurity and the migration enthalpy. The migration energy was calculated using the nudged elastic band method with DFT. The vacancy formation energy, including the entropic contributions to free energies in γ-iron, was evaluated by considering vibrational phonon frequencies based on frozen phonons employing the harmonic approximation for the lattice dynamics. Consequently, we confirmed that the binding energy between large-radius impurities and vacancies is larger than that with an equivalent size of the solvent element, and that the migration enthalpies of these impurities are quite small compared with self diffusion. This finding may indicate that the electronic binding states at the saddle point have a large influence on the migration of impurities

  8. Evaluation and thermodynamic calculation of ureolytic magnesium ammonium phosphate precipitation from UASB effluent at pilot scale.

    Science.gov (United States)

    Desmidt, E; Ghyselbrecht, K; Monballiu, A; Verstraete, W; Meesschaert, B D

    2012-01-01

    The removal of phosphate as magnesium ammonium phosphate (MAP, struvite) has gained a lot of attention. A novel approach using ureolytic MAP crystallization (pH increase by means of bacterial ureases) has been tested on the anaerobic effluent of a potato processing company in a pilot plant and compared with NuReSys(®) technology (pH increase by means of NaOH). The pilot plant showed a high phosphate removal efficiency of 83 ± 7%, resulting in a final effluent concentration of 13 ± 7 mg · L(-1) PO(4)-P. Calculating the evolution of the saturation index (SI) as a function of the remaining concentrations of Mg(2+), PO(4)-P and NH(4)(+) during precipitation in a batch reactor, resulted in a good estimation of the effluent PO(4)-P concentration of the pilot plant, operating under continuous mode. X-ray diffraction (XRD) analyses confirmed the presence of struvite in the small single crystals observed during experiments. The operational cost for the ureolytic MAP crystallization treating high phosphate concentrations (e.g. 100 mg · L(-1) PO(4)-P) was calculated as 3.9 € kg(-1) P(removed). This work shows that the ureolytic MAP crystallization, in combination with an autotrophic nitrogen removal process, is competitive with the NuReSys(®) technology in terms of operational cost and removal efficiency but further research is necessary to obtain larger crystals.

  9. Applicability of special quasi-random structure models in thermodynamic calculations using semi-empirical Debye–Grüneisen theory

    International Nuclear Information System (INIS)

    Kim, Jiwoong

    2015-01-01

    In theoretical calculations, expressing the random distribution of atoms in a certain crystal structure is still challenging. The special quasi-random structure (SQS) model is effective for depicting such random distributions. The SQS model has not been applied to semi-empirical thermodynamic calculations; however, Debye–Grüneisen theory (DGT), a semi-empirical method, was used here for that purpose. The model reliability was obtained by comparing supercell models of various sizes. The results for chemical bonds, pair correlation, and elastic properties demonstrated the reliability of the SQS models. Thermodynamic calculations using density functional perturbation theory (DFPT) and DGT assessed the applicability of the SQS models. DGT and DFPT led to similar variations of the mixing and formation energies. This study provides guidelines for theoretical assessments to obtain the reliable SQS models and to calculate the thermodynamic properties of numerous materials with a random atomic distribution. - Highlights: • Various material properties are used to examine reliability of special quasi-random structures. • SQS models are applied to thermodynamic calculations by semi-empirical methods. • Basic calculation guidelines for materials with random atomic distribution are given.

  10. 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

  11. Phase Transition and Thermodynamics of Ruthenium Diboride via First-Principles Calculations

    International Nuclear Information System (INIS)

    Fen, Luo; Yan, Cheng; Xiang-Rong, Chen; Guang-Fu, Ji

    2009-01-01

    The pressure induced phase transitions of RuB 2 from the OsB 2 -type structure to the ReB 2 -type structure are investigated by first-principles calculations based on the plane-wave basis set with the generalized gradient approximation for exchange and correlation. It is found that the phase transition occurs at 18.6 GPa. We predict the phase transition from the OsB 2 -type RuB 2 to the ReB 2 -type RuB 2 at high temperatures for the first time. The dependences of the heat capacity, thermal expansion coefficient, and the Grüneisen parameter on pressure and temperature for OsB 2 -type RuB 2 and ReB 2 -type RuB 2 are also investigated

  12. Fe-Ni-bearing serpentines from the saprolite horizon of Caribbean Ni-laterite deposits: new insights from thermodynamic calculations

    Science.gov (United States)

    Villanova-de-Benavent, Cristina; Domènech, Cristina; Tauler, Esperança; Galí, Salvador; Tassara, Santiago; Proenza, Joaquín A.

    2017-10-01

    Fe-Ni-bearing serpentine from the saprolite horizon is the main Ni ores in hydrous silicate-type Ni laterites and formed by chemical weathering of partially serpentinized ultramafic rocks under tropical conditions. During lateritization, Mg, Si, and Ni are leached from the surface and transported downwards. Fe2+ is oxidized to Fe3+ and fixed as insoluble Fe-oxyhydroxides (mostly goethite) that incorporate Ni. This Ni is later leached from goethite and incorporated in secondary serpentine and garnierite. As a result, a serpentine-dominated saprolite horizon forms over the ultramafic protolith, overlapped by a Fe-oxyhydroxide-dominated limonite horizon. The serpentine from the protolith (serpentine I) is of hydrothermal origin and yields similar Ni (0.10-0.62 wt.% NiO) and lower Fe (mostly 1.37-5.81 wt.% FeO) concentrations than the primary olivine. In contrast, Fe-Ni-bearing serpentine from the saprolite (serpentine II) shows significantly higher and variable Fe and Ni contents, typically ranging from 2.23 to 15.59 wt.% Fe2O3 and from 1.30 to 7.67 wt.% NiO, suggesting that serpentine get enriched in Fe and Ni under supergene conditions. This study presents detailed mineralogical, textural, and chemical data on this serpentine II, as well as new insights by thermodynamic calculations assuming ideal solution between Fe-, Ni- and Mg-pure serpentines. The aim is to assess if at atmospheric pressure and temperature Fe-Ni-bearing serpentine can be formed by precipitation. Results indicate that the formation of serpentine II under atmospheric pressure and temperature is thermodynamically supported, and pH, Eh, and the equilibrium constant of the reaction are the parameters that affect the results more significantly.

  13. Aging and Phase Stability of Waste Package Outer Barrier

    Energy Technology Data Exchange (ETDEWEB)

    Tammy S. Edgecumble Summers

    2001-08-23

    This Analysis Model Report (AMR) was prepared in accordance with the Work Direction and Planning Document, ''Aging and Phase Stability of Waste Package Outer Barrier'' (CRWMS M&O 1999a). ICN 01 of this AMR was developed following guidelines provided in TWP-MGR-MD-000004 REV 01, ''Technical Work Plan for: Integrated Management of Technical Product Input Department'' (BSC 2001, Addendum B). It takes into consideration the Enhanced Design Alternative II (EDA II), which has been selected as the preferred design for the Engineered Barrier System (EBS) by the License Application Design Selection (LADS) program team (CRWMS M&O 1999b). The salient features of the EDA II design for this model are a waste package (WP) consisting of an outer barrier of Alloy 22 and an inner barrier of Type 316L stainless steel. This report provides information on the phase stability of Alloy 22l, the current waste-package-outer-barrier (WPOB) material. These phase stability studies are currently divided into three general areas: (1) Long-range order reactions; (2) Intermetallic and carbide precipitation in the base metal; and (3) Intermetallic and carbide precipitation in welded samples.

  14. Additive manufacturing of a functionally graded material from Ti-6Al-4V to Invar: Experimental characterization and thermodynamic calculations

    International Nuclear Information System (INIS)

    Bobbio, Lourdes D.; Otis, Richard A.; Borgonia, John Paul; Dillon, R. Peter; Shapiro, Andrew A.; Liu, Zi-Kui; Beese, Allison M.

    2017-01-01

    In functionally graded materials (FGMs), the elemental composition, or structure, within a component varies gradually as a function of position, allowing for the gradual transition from one alloy to another, and the local tailoring of properties. One method for fabricating FGMs with varying elemental composition is through layer-by-layer directed energy deposition additive manufacturing. This work combines experimental characterization and computational analysis to investigate a material graded from Ti-6Al-4V to Invar 36 (64 wt% Fe, 36 wt% Ni). The microstructure, composition, phases, and microhardness were determined as a function of position within the FGM. During the fabrication process, detrimental phases associated with the compositional blending of the Ti-6Al-4V and Invar formed, leading to cracking in the final deposited part. Intermetallic phases (FeTi, Fe_2Ti, Ni_3Ti, and NiTi_2) were experimentally identified to occur throughout the gradient region, and were considered as the reason that the FGM cracked during fabrication. CALPHAD (CALculation of PHase Diagrams) thermodynamic calculations were used concurrently to predict phases that would form during the manufacturing process and were compared to the experimental results. The experimental-computational approach described herein for characterizing FGMs can be used to improve the understanding and design of other FGMs.

  15. Calculation of thermodynamic properties and transport coefficients of C5F10O-CO2 thermal plasmas

    Science.gov (United States)

    Li, Xingwen; Guo, Xiaoxue; Murphy, Anthony B.; Zhao, Hu; Wu, Jian; Guo, Ze

    2017-10-01

    The thermodynamic properties and transport coefficients of C5F10O-CO2 gas mixtures, which are being considered as substitutes for SF6 in circuit breaker applications, are calculated for the temperature range from 300 K to 30 000 K and the pressure range from 0.05 MPa to 1.6 MPa. Special attention is paid on investigating the evolution of thermophysical properties of C5F10O-CO2 mixtures with different mixing ratios and with different pressures; both the mixing ratio and pressure significantly affect the properties. This is explained mainly in terms of the changes in the temperatures at which the dissociation and ionization reactions take place. Comparisons of different thermophysical properties of C5F10O-CO2 mixtures with those of SF6 are also carried out. It is found that most of the thermophysical properties of the C5F10O-CO2 mixtures, such as thermal conductivity, viscosity, and electrical conductivity, become closer to those of SF6 as the C5F10O concentration increases. The composition and thermophysical properties of pure C5F10O in the temperature range from 300 K to 2000 K based on the decomposition pathway are also given. The calculation results provide a basis for further study of the insulation and arc-quenching capability of C5F10O-CO2 gas mixtures as substitutes for SF6.

  16. Dataset on the structure and thermodynamic and dynamic stability of Mo2ScAlC2 from experiments and first-principles calculations

    Directory of Open Access Journals (Sweden)

    Martin Dahlqvist

    2017-02-01

    Full Text Available The data presented in this paper are related to the research article entitled “Theoretical stability and materials synthesis of a chemically ordered MAX phase, Mo2ScAlC2, and its two-dimensional derivate Mo2ScC” (Meshkian et al. 2017 [1]. This paper describes theoretical phase stability calculations of the MAX phase alloy MoxSc3-xAlC2 (x=0, 1, 2, 3, including chemical disorder and out-of-plane order of Mo and Sc along with related phonon dispersion and Bader charges, and Rietveld refinement of Mo2ScAlC2. The data is made publicly available to enable critical or extended analyzes.

  17. Interactions of ionic liquids and acetone: thermodynamic properties, quantum-chemical calculations, and NMR analysis.

    Science.gov (United States)

    Ruiz, Elia; Ferro, Victor R; Palomar, Jose; Ortega, Juan; Rodriguez, Juan Jose

    2013-06-20

    The interactions between ionic liquids (ILs) and acetone have been studied to obtain a further understanding of the behavior of their mixtures, which generally give place to an exothermic process, mutual miscibility, and negative deviation of Raoult's law. COSMO-RS was used as a suitable computational method to systematically analyze the excess enthalpy of IL-acetone systems (>300), in terms of the intermolecular interactions contributing to the mixture behavior. Spectroscopic and COSMO-RS results indicated that acetone, as a polar compound with strong hydrogen bond acceptor character, in most cases, establishes favorable hydrogen bonding with ILs. This interaction is strengthened by the presence of an acidic cation and an anion with dispersed charge and non-HB acceptor character in the IL. COSMO-RS predictions indicated that gas-liquid and vapor-liquid equilibrium data for IL-acetone systems can be finely tuned by the IL selection, that is, acting on the intermolecular interactions between the molecular and ionic species in the liquid phase. NMR measurements for IL-acetone mixtures at different concentrations were also carried out. Quantum-chemical calculations by using molecular clusters of acetone and IL species were finally performed. These results provided additional evidence of the main role played by hydrogen bonding in the behavior of systems containing ILs and HB acceptor compounds, such as acetone.

  18. Structure, elastic properties and phase stability of Cr1-xAlxN

    International Nuclear Information System (INIS)

    Mayrhofer, P.H.; Music, D.; Reeswinkel, Th.; Fuss, H.-G.; Schneider, J.M.

    2008-01-01

    The effect of composition and metal sublattice population on the phase stability, structure and elastic properties of cubic (c), hexagonal (h) and orthorhombic spin-polarized Cr 1-x Al x N was studied using ab initio calculations. Excellent correlation between ab initio and experimentally obtained lattice parameters and elastic constants was obtained. The energy of formation suggests that the cubic phase can be stabilized for x in the range 0.48-0.75, depending on the metal sublattice population. The broad range of x, which is also observed in experiments, can be understood by considering the Al distribution induced changes in the configurational contribution to the total energy

  19. Investigation of phase stability in the scandia-zirconia; Investigacao da estabilidade de fases da zirconia-escandia

    Energy Technology Data Exchange (ETDEWEB)

    Grosso, Robson Lopes

    2016-11-01

    In this work, the phase stability of scandia-zirconia (ScSZ) system was investigated by the thermodynamic study of nanoparticles, within the range of 0 to 20 mol% Sc{sub 2}O{sub 3}, and by codoping of ZrO{sub 2}-10 mol% Sc{sub 2}O{sub 3} (10ScSZ) with Dy{sub 2}O{sub 3} and Nb{sub 2}O{sub 5}. The phase stability of ScSZ was evaluated based on thermodynamic data collected by water adsorption microcalorimetry and high temperature oxide melt solution. Nanostructured zirconia-scandia solid solutions were synthesized by coprecipitation method. Thermodynamic data were determined for ScSZ polymorph (monoclinic, tetragonal, cubic, rhombohedral β and γ) found by X-ray diffraction. This systemic work resulted in an unprecedented phase diagram at the nanoscale of particle size-composition. The effects of additives on 10ScSZ were investigated aiming to stabilize the cubic (c) structure at room temperature and to suppress the characteristic cubic-rhombohedral β phase transformation. Compositions were prepared by coprecipitation and solid state reaction. Materials were sintered by conventional and spark plasma sintering. Full stabilization of the cubic phase was attained by 1 mol% Dy{sub 2}O{sub 3} and 0.5 mol% Nb{sub 2}O{sub 5} additions. The smallest Nb{sub 2}O{sub 5} content required for cubic phase stabilization was attributed to liquid phase formation during sintering and to small ionic radius of Nb{sup 5+}. Results of high temperature X-ray diffraction and thermal analysis show suppression of the c-β transformation. Samples containing 0.5 mol% Nb{sub 2}O{sub 5} show total ionic conductivity similar to 10ScSZ without additives within a broad temperature range with high stability during 170 h at 600 °C. (author)

  20. 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.)

  1. Study on the intrinsic defects in ZnO by combing first-principle and thermodynamic calculations

    Science.gov (United States)

    Ma, Changmin; Liu, Tingyu; Chang, Qiuxiang

    2015-11-01

    In this paper, the intrinsic point defects in ZnO crystal have been studied by the approach that integrates first-principles, thermodynamic calculations and the contributions of vibrational entropy. With temperature increasing and oxygen partial pressure decreasing, the formation energies of oxygen vacancy (VO), zinc interstitial (Zni) and zinc anti-site (ZnO) are decreasing, while it increases for zinc vacancy (VZn), oxygen interstitial (Oi) and oxygen anti-site (OZn). They are more sensitive to temperature than oxygen partial pressure. There are two interesting phenomena. First, VO or VZn have the lowest formation energies for whole Fermi level at special environment condition (such as at T = 300K, about PO2 = 10-10atm or T = 1500K, about PO2 = 104atm) and intrinsic p-type doping of ZnO is possible by VZn at these special conditions. Second, VO as donors have lowest formation energy for all Fermi level at high temperature and low oxygen partial pressure (T = 1500K, PO2 = 10-10atm). According to our analysis, the VO could produce n-type doping in ZnO at these special conditions and change p-type ZnO to n-type ZnO at condition from low temperature and high oxygen partial pressure to high temperature and low oxygen partial pressure.

  2. Effect of alloying elements on the stability of Ni2M in Alloy690 based upon thermodynamic calculation

    International Nuclear Information System (INIS)

    Horiuchi, Toshiaki; Kuwano, Kazuhiro; Satoh, Naohiro

    2012-01-01

    Some researchers recently point out that Ni based alloys used in nuclear power plants have the ordering tendency, which is a potential to decrease mechanical properties within the expected lifetime of the plants. In the present study, authors evaluated the effect of 8 alloying elements on the ordering tendency in Alloy690 based upon thermodynamic calculation by Thermo-Calc. It is clarified that the additive amount of Fe, Cr, Ti and Si, particularly Fe and Cr, was influential for the stability of Ni 2 M, while that of Mn, Cu, B and C had almost no effect for that. Authors therefore designed the Ni 2 M stabilized alloy by no addition of Fe in Alloy690. Ni 2 M is estimated to be stable even at 773 K in the Ni 2 M stabilized alloy. The influence by long range ordering or precipitating of Ni 2 M in Alloy690 for mechanical properties or SCC susceptibility is expected to be clarified by the sample obtained in the present study. (author)

  3. Phase stability of random brasses: pseudopotential theory revisited

    International Nuclear Information System (INIS)

    Rahman, S.M.M.

    1987-06-01

    We review the theoretical development concerning the phase stability of random brasses. The introductory discussion of the subject embraces the rules of metallurgy in general, but we emphasize on the roles of electron-per-atom ratio in the major bulk of our discussion. Starting from the so-called rigid-band model the discussion goes up to the recent higher-order pseudopotential theory. The theoretical refinements within the pseudopotential framework are discussed briefly. The stability criteria of the random phases are analysed both in the static lattice and dynamic lattice approximations. (author). 71 refs, figs and tabs

  4. Structural, electronic, magnetic and thermodynamic properties of Ni1-xTixO alloys an ab initio calculation and Monte Carlo study

    Science.gov (United States)

    Klaa, K.; Labidi, S.; Masrour, R.; Jabar, A.; Labidi, M.; Amara, A.; Drici, A.; Hlil, E. K.; Ellouze, M.

    2018-06-01

    Structural, electronic, magnetic and thermodynamic main features for Ni1-xTixO ternary alloys in rock-salt structure with Ti content in the range ? were studied using the full potential Linearized augmented plane wave (FP-LAPW) method within density functional theory. The exchange-correlation potential was calculated by the generalized gradient approximation. The analysis of the electronic density of states curves allowed the computation of the magnetic moments which are considered to lie along (010) axes. The thermodynamic stability of this alloy was investigated by calculating the excess enthalpy of mixing ? as well as the phase diagram. In addition, the Monte Carlo simulations have been exploited to calculate the transition temperature and magnetic coercive field in the alloy.

  5. 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.

  6. Analysis of the influence of the plasma thermodynamic regime in the spectrally resolved and mean radiative opacity calculations of carbon plasmas in a wide range of density and temperature

    International Nuclear Information System (INIS)

    Gil, J.M.; Rodriguez, R.; Martel, P.; Florido, R.; Rubiano, J.G.; Mendoza, M.A.; Minguez, E.

    2013-01-01

    In this work the spectrally resolved, multigroup and mean radiative opacities of carbon plasmas are calculated for a wide range of plasma conditions which cover situations where corona, local thermodynamic and non-local thermodynamic equilibrium regimes are found. An analysis of the influence of the thermodynamic regime on these magnitudes is also carried out by means of comparisons of the results obtained from collisional-radiative, corona or Saha–Boltzmann equations. All the calculations presented in this work were performed using ABAKO/RAPCAL code. -- Highlights: ► Spectrally resolved, multigroup and mean radiative opacities of carbon plasmas are calculated. ► Corona, local thermodynamic and non-local thermodynamic equilibrium regimes are analyzed. ► Simulations performed using the computational package ABAKO/RAPCAL. ► A criterion for the establishment of the thermodynamic regime is proposed.

  7. Search for promising compositions for developing new multiphase casting alloys based on Al-Cu-Mg matrix using thermodynamic calculations and mathematic simulation

    Science.gov (United States)

    Zolotorevskii, V. S.; Pozdnyakov, A. V.; Churyumov, A. Yu.

    2012-11-01

    A calculation-experimental study is carried out to improve the concept of searching for new alloying systems in order to develop new casting alloys using mathematical simulation methods in combination with thermodynamic calculations. The results show the high effectiveness of the applied methods. The real possibility of selecting the promising compositions with the required set of casting and mechanical properties is exemplified by alloys with thermally hardened Al-Cu and Al-Cu-Mg matrices, as well as poorly soluble additives that form eutectic components using mainly the calculation study methods and the minimum number of experiments.

  8. Temperature, pressure, and electrochemical constraints on protein speciation: Group additivity calculation of the standard molal thermodynamic properties of ionized unfolded proteins

    Directory of Open Access Journals (Sweden)

    J. M. Dick

    2006-01-01

    Full Text Available Thermodynamic calculations can be used to quantify environmental constraints on the speciation of proteins, such as the pH and temperature dependence of ionization state, and the relative chemical stabilities of proteins in different biogeochemical settings. These calculations depend in part on values of the standard molal Gibbs energies of proteins and their ionization reactions as a function of temperature and pressure. Because these values are not generally available, we calculated values of the standard molal thermodynamic properties at 25°C and 1 bar as well as the revised Helgeson-Kirkham-Flowers equations of state parameters of neutral and charged zwitterionic reference model compounds including aqueous amino acids, polypeptides, and unfolded proteins. The experimental calorimetric and volumetric data for these species taken from the literature were combined with group additivity algorithms to calculate the properties and parameters of neutral and ionized sidechain and backbone groups in unfolded proteins. The resulting set of group contributions enables the calculation of the standard molal Gibbs energy, enthalpy, entropy, isobaric heat capacity, volume, and isothermal compressibility of unfolded proteins in a range of proton ionization states to temperatures and pressures exceeding 100°C and 1000 bar. This approach provides a useful frame of reference for thermodynamic studies of protein folding and complexation reactions. It can also be used to assign provisional values of the net charge and Gibbs energy of ionized proteins as a function of temperature and pH. Using these values, an Eh-pH diagram for a reaction representing the speciation of extracellular proteins from Pyrococcus furiosus and Bacillus subtilis was generated. The predicted predominance limits of these proteins correspond with the different electrochemical conditions of hydrothermal vents and soils. More comprehensive calculations of this kind may reveal pervasive

  9. Modelling reactive material transport in the near field of a repository for radioactive waste. Coupling the EMOS near field modules CLAYPOS and LOPOS with thermodynamic equilibrium calculations

    International Nuclear Information System (INIS)

    Moog, H.C.; Keesmann, S.M.

    2007-02-01

    This paper reports on the project ''Coupling transport models with thermodynamic equilibrium calculations'' - short title EQLINK, promotion code number 02 E 9723 - in the which the scope for coupling thermodynamic equilibrium model calculations with EMOS was expanded and improved. The first step was to inquire into the current state of research on radiolytic processes. It transpired that there is currently no conclusive description of radiolytic processes. The existing descriptions are too complex and too narrowly geared to specific scenarios to allow a general view on radiolytic processes, which would be a prerequisite for creating suitable long-term geochemical safety analysis modules. It appears that the approximation calculations implemented in EMOS tend to overestimate rather than underestimate radiolytic gas formation. The thermodynamic database which is used at GRS (Society for Plant and Reactor Safety) as a basis for coupled transport calculations has been updated. For this purpose the radionuclide database of the Institut fuer Nukleare Entsorgung (INE = Institute for Nuclear Disposal) was converted to an in-house format which permits creating parameter files for specific requirements. The data of the INE comprise thermodynamic parameters such as equilibrium constants, Gibbs free enthalpies of formation, enthalpies and entropies of formation and Pitzer parameters, which are required for model calculations on high-saline solutions. The database for low-saline solutions which had been developed by PSI/NAGRA for calculations with CLAYPOS was also adopted. Both parameter sets were subjected to test calculations to detect any errors that might have occurred during the data transfer. It is thus now possible to perform coupled transport calculations with the EMOS modules LOPOS and CLAYPOS according to the state of the art of geochemical research. The EQLINK interface which had been developed in an earlier project, titled ''Development of a model for describing the

  10. Solid phase stability of a double-minimum interaction potential system

    International Nuclear Information System (INIS)

    Suematsu, Ayumi; Yoshimori, Akira; Saiki, Masafumi; Matsui, Jun; Odagaki, Takashi

    2014-01-01

    We study phase stability of a system with double-minimum interaction potential in a wide range of parameters by a thermodynamic perturbation theory. The present double-minimum potential is the Lennard-Jones-Gauss potential, which has a Gaussian pocket as well as a standard Lennard-Jones minimum. As a function of the depth and position of the Gaussian pocket in the potential, we determine the coexistence pressure of crystals (fcc and bcc). We show that the fcc crystallizes even at zero pressure when the position of the Gaussian pocket is coincident with the first or third nearest neighbor site of the fcc crystal. The bcc crystal is more stable than the fcc crystal when the position of the Gaussian pocket is coincident with the second nearest neighbor sites of the bcc crystal. The stable crystal structure is determined by the position of the Gaussian pocket. These results show that we can control the stability of the solid phase by tuning the potential function

  11. Thermodynamic modeling to analyse composition of carbonaceous ...

    Indian Academy of Sciences (India)

    Equilibrium thermodynamic analysis has been applied to the low-pressure MOCVD process using manganese acetylacetonate as the precursor. ``CVD phase stability diagrams” have been constructed separately for the processes carried out in argon and oxygen ambient, depicting the compositions of the resulting films as ...

  12. Thermodynamic and kinetic modelling: creep resistant materials

    DEFF Research Database (Denmark)

    Hald, John; Korcakova, L.; Danielsen, Hilmar Kjartansson

    2008-01-01

    The use of thermodynamic and kinetic modelling of microstructure evolution in materials exposed to high temperatures in power plants is demonstrated with two examples. Precipitate stability in martensitic 9–12%Cr steels is modelled including equilibrium phase stability, growth of Laves phase part...

  13. Group additivity calculations of the thermodynamic properties of unfolded proteins in aqueous solution: a critical comparison of peptide-based and HKF models.

    Science.gov (United States)

    Hakin, A W; Hedwig, G R

    2001-02-15

    A recent paper in this journal [Amend and Helgeson, Biophys. Chem. 84 (2000) 105] presented a new group additivity model to calculate various thermodynamic properties of unfolded proteins in aqueous solution. The parameters given for the revised Helgeson-Kirkham-Flowers (HKF) equations of state for all the constituent groups of unfolded proteins can be used, in principle, to calculate the partial molar heat capacity, C(o)p.2, and volume, V2(0), at infinite dilution of any polypeptide. Calculations of the values of C(o)p.2 and V2(0) for several polypeptides have been carried out to test the predictive utility of the HKF group additivity model. The results obtained are in very poor agreement with experimental data, and also with results calculated using a peptide-based group additivity model. A critical assessment of these two additivity models is presented.

  14. Thermodynamics of InxGa1-xN MOVPE using x-dependent interaction parameter

    International Nuclear Information System (INIS)

    Moon, Won Ha; Kim, Changsung Sean; Choi, Chang Hwan

    2007-01-01

    Thermodynamic properties of In x Ga 1-x N MOVPE are investigated using x-dependent interaction parameter. The interaction parameter (Ω=-1.3435x+6.1607 (kcal/mol)) dependent on In composition is calculated using a molecular-mechanics method to investigate the phase stability of InGaN. This parameter is more reliable than that proposed until now. The phase diagram and critical temperature (1392 K at x=0.44) of In x Ga 1-x N are also obtained. With this interaction parameter, many thermodynamic characteristics of InGaN by the change of In composition, input V/III ratio, and input mol ratio of group III sources are calculated to predict the growth condition of InGaN. These results are in agreement with other data for InGaN. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Tethered Nanoparticle–Polymer Composites: Phase Stability and Curvature

    KAUST Repository

    Srivastava, Samanvaya

    2012-04-17

    Phase behavior of poly(ethylene glycol) (PEG) tethered silica nanoparticles dispersed in PEG hosts is investigated using small-angle X-ray scattering. Phase separation in dispersions of densely grafted nanoparticles is found to display strikingly different small-angle X-ray scattering signatures in comparison to phase-separated composites comprised of bare or sparsely grafted nanoparticles. A general diagram for the dispersion state and phase stability of polymer tethered nanoparticle-polymer composites incorporating results from this as well as various other contemporary studies is presented. We show that in the range of moderate to high grafting densities the dispersion state of nanoparticles in composites is largely insensitive to the grafting density of the tethered chains and chemistry of the polymer host. Instead, the ratio of the particle diameter to the size of the tethered chain and the ratio of the molecular weights of the host and tethered polymer chains (P/N) are shown to play a dominant role. Additionally, we find that well-functionalized nanoparticles form stable dispersions in their polymer host beyond the P/N limit that demarcates the wetting/dewetting transition in polymer brushes on flat substrates interacting with polymer melts. A general strategy for achieving uniform nanoparticle dispersion in polymers is proposed. © 2012 American Chemical Society.

  16. Understanding Oxygen Vacancy Formation, Interaction, Transport, and Strain in SOFC Components via Combined Thermodynamics and First Principles Calculations

    Science.gov (United States)

    Das, Tridip

    temperature and oxygen partial pressure, for multiple LSF compositions and phases using a combined thermodynamics and DFT approach. A detailed oxygen vacancy migration barrier calculation gave the oxygen ionic diffusivity and conductivity. Oxygen vacancy also causes chemical strain, which was treated as a scalar in the literature. However, in many materials, it should be a tensor, which is anisotropic. We illustrate this effect on CeO2, in which it explained a puzzling experiment, which shows significant amplification of measured strain on applied bias in non-stoichiometric Gd doped ceria. The presence of highly localized 4f valence orbital in Ce causes charge disproportionation on the formation of neutral oxygen vacancy, producing anisotropic chemical strain in ceria with cubic symmetry. Understanding of delta and X and anisotropic chemical strain in the lattice has led to the design of better MIEC via element doping and strain engineering of the lattice.

  17. QSPR models based on molecular mechanics and quantum chemical calculations. 2. Thermodynamic properties of alkanes, alcohols, polyols, and ethers

    DEFF Research Database (Denmark)

    Dyekjær, Jane Dannow; Jonsdottir, Svava Osk

    2003-01-01

    Quantitative Structure-Property Relationship (QSPR) models for prediction of various thermodynamic properties of simple organic compounds have been developed. A number of new descriptors are proposed and used alongside with descriptors available within the Codessa program. An important feature...... for alkanes, alcohols, diols, ethers, and oxyalcohols, including cyclic alkanes and alcohols. Several good models, having good predictability, have been developed. To enhance the applicability of the QSPR models, simpler expressions for each descriptor have also been developed. This allows for the prediction...

  18. Lattice stabilities, mechanical and thermodynamic properties of Al3Tm and Al3Lu intermetallics under high pressure from first-principles calculations

    Science.gov (United States)

    Xu-Dong, Zhang; Wei, Jiang

    2016-02-01

    The effects of high pressure on lattice stability, mechanical and thermodynamic properties of L12 structure Al3Tm and Al3Lu are studied by first-principles calculations within the VASP code. The phonon dispersion curves and density of phonon states are calculated by using the PHONONPY code. Our results agree well with the available experimental and theoretical values. The vibrational properties indicate that Al3Tm and Al3Lu keep their dynamical stabilities in L12 structure up to 100 GPa. The elastic properties and Debye temperatures for Al3Tm and Al3Lu increase with the increase of pressure. The mechanical anisotropic properties are discussed by using anisotropic indices AG, AU, AZ, and the three-dimensional (3D) curved surface of Young’s modulus. The calculated results show that Al3Tm and Al3Lu are both isotropic at 0 GPa and anisotropic under high pressure. In the present work, the sound velocities in different directions for Al3Tm and Al3Lu are also predicted under high pressure. We also calculate the thermodynamic properties and provide the relationships between thermal parameters and temperature/pressure. These results can provide theoretical support for further experimental work and industrial applications. Project supported by the Scientific Technology Plan of the Educational Department of Liaoning Province and Liaoning Innovative Research Team in University, China (Grant No. LT2014004) and the Program for the Young Teacher Cultivation Fund of Shenyang University of Technology, China (Grant No. 005612).

  19. Computational Design and Discovery of Ni-Based Alloys and Coatings: Thermodynamic Approaches Validated by Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zi-Kui [Pennsylvania State University; Gleeson, Brian [University of Pittsburgh; Shang, Shunli [Pennsylvania State University; Gheno, Thomas [University of Pittsburgh; Lindwall, Greta [Pennsylvania State University; Zhou, Bi-Cheng [Pennsylvania State University; Liu, Xuan [Pennsylvania State University; Ross, Austin [Pennsylvania State University

    2018-04-23

    This project developed computational tools that can complement and support experimental efforts in order to enable discovery and more efficient development of Ni-base structural materials and coatings. The project goal was reached through an integrated computation-predictive and experimental-validation approach, including first-principles calculations, thermodynamic CALPHAD (CALculation of PHAse Diagram), and experimental investigations on compositions relevant to Ni-base superalloys and coatings in terms of oxide layer growth and microstructure stabilities. The developed description included composition ranges typical for coating alloys and, hence, allow for prediction of thermodynamic properties for these material systems. The calculation of phase compositions, phase fraction, and phase stabilities, which are directly related to properties such as ductility and strength, was a valuable contribution, along with the collection of computational tools that are required to meet the increasing demands for strong, ductile and environmentally-protective coatings. Specifically, a suitable thermodynamic description for the Ni-Al-Cr-Co-Si-Hf-Y system was developed for bulk alloy and coating compositions. Experiments were performed to validate and refine the thermodynamics from the CALPHAD modeling approach. Additionally, alloys produced using predictions from the current computational models were studied in terms of their oxidation performance. Finally, results obtained from experiments aided in the development of a thermodynamic modeling automation tool called ESPEI/pycalphad - for more rapid discovery and development of new materials.

  20. Calculating Water Thermodynamics in the Binding Site of Proteins - Applications of WaterMap to Drug Discovery.

    Science.gov (United States)

    Cappel, Daniel; Sherman, Woody; Beuming, Thijs

    2017-01-01

    The ability to accurately characterize the solvation properties (water locations and thermodynamics) of biomolecules is of great importance to drug discovery. While crystallography, NMR, and other experimental techniques can assist in determining the structure of water networks in proteins and protein-ligand complexes, most water molecules are not fully resolved and accurately placed. Furthermore, understanding the energetic effects of solvation and desolvation on binding requires an analysis of the thermodynamic properties of solvent involved in the interaction between ligands and proteins. WaterMap is a molecular dynamics-based computational method that uses statistical mechanics to describe the thermodynamic properties (entropy, enthalpy, and free energy) of water molecules at the surface of proteins. This method can be used to assess the solvent contributions to ligand binding affinity and to guide lead optimization. In this review, we provide a comprehensive summary of published uses of WaterMap, including applications to lead optimization, virtual screening, selectivity analysis, ligand pose prediction, and druggability assessment. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  1. Nature of low dimensional structural modulations and relative phase stability in RexMo(W)1-xS2 transition metal dichalcogenide alloys

    KAUST Repository

    Sahu, R.; Bhat, U.; Batra, Nitin M; Sharona, H.; Vishal, B.; Sarkar, S.; Devi, Assa Aravindh Sasikala; Peter, S. C.; Roqan, Iman S.; Costa , P. M. F. J.; Datta, Ranjan

    2017-01-01

    We report on the various types of Peierls like two dimensional structural modulations and relative phase stability of 2H and 1T poly-types in the RexMo1-xS2 and RexW1-xS2 alloy system. Theoretical calculation predicts a polytype phase transition

  2. Phase stability of TiO2 polymorphs from diffusion Quantum Monte Carlo

    International Nuclear Information System (INIS)

    Luo, Ye; Benali, Anouar; Shulenburger, Luke; Krogel, Jaron T; Heinonen, Olle; Kent, Paul R C

    2016-01-01

    Titanium dioxide, TiO 2 , has multiple applications in catalysis, energy conversion and memristive devices because of its electronic structure. Most of these applications utilize the naturally existing phases: rutile, anatase and brookite. Despite the simple form of TiO 2 and its wide uses, there is long-standing disagreement between theory and experiment on the energetic ordering of these phases that has never been resolved. We present the first analysis of phase stability at zero temperature using the highly accurate many-body fixed node diffusion Quantum Monte Carlo (QMC) method. We also include the effects of temperature by calculating the Helmholtz free energy including both internal energy and vibrational contributions from density functional perturbation theory based quasi harmonic phonon calculations. Our QMC calculations find that anatase is the most stable phase at zero temperature, consistent with many previous mean-field calculations. However, at elevated temperatures, rutile becomes the most stable phase. For all finite temperatures, brookite is always the least stable phase. (paper)

  3. 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

  4. The principle of phase stability and the accelerator program at Berkeley, 1945--1954

    International Nuclear Information System (INIS)

    Lofgren, E.J.

    1994-07-01

    The discovery of the Principle of Phase Stability by Vladimir Veksler and Edwin McMillian and the end of the war released a surge of accelerator activity at the Lawrence Berkeley Laboratory (then The University of California Radiation Laboratory). Six accelerators incorporating the Principle of Phase Stability were built in the period 1945--1954

  5. Electronic, elastic, thermodynamic properties and structure disorder of {gamma}-AlON solid solution from ab initio calculations

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yuezhong, E-mail: wyzphysics@163.com [Department of Physics and Key Laboratory for Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Tianjin Jinhang Institute of Technical Physics, Tianjin 300192 (China); Lu, Tiecheng, E-mail: lutiecheng@scu.edu.cn [Department of Physics and Key Laboratory for Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); International Center for Material Physics, Chinese Academy of Sciences, Shenyang 110015 (China); Zhang, Rongshi [Tianjin Jinhang Institute of Technical Physics, Tianjin 300192 (China); Jiang, Shengli; Qi, Jianqi; Wang, Ying [Department of Physics and Key Laboratory for Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Chen, Qingyun [Department of Physics and Key Laboratory for Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); National Defense Key Discipline Laboratory of Nuclear Waste and Environmental Safety, Southwest University of Science and Technology, Mianyang 621010 (China); Miao, Naihua [Physique Theorique des Materiaux, Universite de Liege, Sart Tilman B-4000 (Belgium); He, Duanwei [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610064 (China)

    2013-01-25

    Highlights: Black-Right-Pointing-Pointer We reassess the chemical bonding character of {gamma}-AlON which shows strong ionicity. Black-Right-Pointing-Pointer {gamma}-AlON single-crystals exhibit highly elastic anisotropy. Black-Right-Pointing-Pointer The thermodynamic properties are investigated in a wider temperature/pressure range. Black-Right-Pointing-Pointer {gamma}-AlON is an O/N partially disordered structure. - Abstract: Spinel aluminium oxynitride ({gamma}-AlON), as a kind of transparent ceramic material expectable, is studied using the ab initio density functional method, in terms of electronic, elastic, thermodynamic properties and structure disorder. The results show that {gamma}-AlON exhibits strong ionicity, as quantitatively expressed by (Al{sub O}{sup 2.43+}){sub 15}(Al{sub T}{sup 2.41+}){sub 8}(O{sup 1.64-}){sub 27}(N{sup 2.27-}){sub 5} from our reassessment of the ionic character. We summarize and speculate that the considered oxynitride single-crystals exhibit highly elastic anisotropy. The interpretation of the thermodynamic properties of {gamma}-AlON according to quasi-harmonic Debye model confirm the available experiments and are extended to a wider temperature/pressure range. This material holds high elastic strength under extreme environments, where dB/dT absolute value is less than 0.03 GPa/K, independent of the pressure. Finally, we study the O/N structure disorder character of {gamma}-AlON solid solution by investigating nine possible crystal structures. It is found that {gamma}-AlON should be partially disordered, and in fact, the O/N ordering has a significant effect on the properties.

  6. Electronic, elastic, thermodynamic properties and structure disorder of γ-AlON solid solution from ab initio calculations

    International Nuclear Information System (INIS)

    Wang, Yuezhong; Lu, Tiecheng; Zhang, Rongshi; Jiang, Shengli; Qi, Jianqi; Wang, Ying; Chen, Qingyun; Miao, Naihua; He, Duanwei

    2013-01-01

    Highlights: ► We reassess the chemical bonding character of γ-AlON which shows strong ionicity. ► γ-AlON single-crystals exhibit highly elastic anisotropy. ► The thermodynamic properties are investigated in a wider temperature/pressure range. ► γ-AlON is an O/N partially disordered structure. - Abstract: Spinel aluminium oxynitride (γ-AlON), as a kind of transparent ceramic material expectable, is studied using the ab initio density functional method, in terms of electronic, elastic, thermodynamic properties and structure disorder. The results show that γ-AlON exhibits strong ionicity, as quantitatively expressed by (Al O 2.43+ ) 15 (Al T 2.41+ ) 8 (O 1.64- ) 27 (N 2.27- ) 5 from our reassessment of the ionic character. We summarize and speculate that the considered oxynitride single-crystals exhibit highly elastic anisotropy. The interpretation of the thermodynamic properties of γ-AlON according to quasi-harmonic Debye model confirm the available experiments and are extended to a wider temperature/pressure range. This material holds high elastic strength under extreme environments, where dB/dT absolute value is less than 0.03 GPa/K, independent of the pressure. Finally, we study the O/N structure disorder character of γ-AlON solid solution by investigating nine possible crystal structures. It is found that γ-AlON should be partially disordered, and in fact, the O/N ordering has a significant effect on the properties.

  7. Calculation of thermodynamic properties of sodium and potassium vapors on the base of semiempirical state equation. Group integrals and virial coefficients

    International Nuclear Information System (INIS)

    Reva, T.D.; Semenov, A.M.

    1984-01-01

    Statistically significant estimations of the second, third and fourth group integrals of sodium and potassium vapors were obtained in the framework of the initial atom method on the basis of semiempirical equation of state derived by the authors. Possibility is duscussed of estimating dimer, trimer and tetramer concentrations from these data with account of unideality of vapors. High rate of convergence of density and pressure group expansion is demonstrated. Virial coefficients were calculated. It is shown that virial expansions of thermodynamic functions diverge at elevated densities of the gases under study. The estimations of senior virial coefficients of sodium and potassium vapors available in literature were proved to be faulty

  8. Calculation of the Aqueous Thermodynamic Properties of Citric Acid Cycle Intermediates and Precursors and the Estimation of High Temperature and Pressure Equation of State Parameters

    Directory of Open Access Journals (Sweden)

    Mitchell Schulte

    2009-06-01

    Full Text Available The citric acid cycle (CAC is the central pathway of energy transfer for many organisms, and understanding the origin of this pathway may provide insight into the origins of metabolism. In order to assess the thermodynamics of this key pathway for microorganisms that inhabit a wide variety of environments, especially those found in high temperature environments, we have calculated the properties and parameters for the revised Helgeson-Kirkham-Flowers equation of state for the major components of the CAC. While a significant amount of data is not available for many of the constituents of this fundamental pathway, methods exist that allow estimation of these missing data.

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

    KAUST Repository

    Kou, Jisheng

    2017-09-30

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

  10. Thermodynamic properties and solidification kinetics of intermetallic Ni7Zr2 alloy investigated by electrostatic levitation technique and theoretical calculations

    International Nuclear Information System (INIS)

    Li, L. H.; Hu, L.; Yang, S. J.; Wang, W. L.; Wei, B.

    2016-01-01

    The thermodynamic properties, including the density, volume expansion coefficient, ratio of specific heat to emissivity of intermetallic Ni 7 Zr 2 alloy, have been measured using the non-contact electrostatic levitation technique. These properties vary linearly with temperature at solid and liquid states, even down to the obtained maximum undercooling of 317 K. The enthalpy, glass transition, diffusion coefficient, shear viscosity, and surface tension were obtained by using molecular dynamics simulations. Ni 7 Zr 2 has a relatively poor glass forming ability, and the glass transition temperature is determined as 1026 K. The inter-diffusivity of Ni 7 Zr 2 alloy fitted by Vogel–Fulcher–Tammann law yields a fragility parameter of 8.49, which indicates the fragile nature of this alloy. Due to the competition of increased thermodynamic driving force and decreased atomic diffusion, the dendrite growth velocity of Ni 7 Zr 2 compound exhibits double-exponential relationship to the undercooling. The maximum growth velocity is predicted to be 0.45 m s −1 at the undercooling of 335 K. Theoretical analysis reveals that the dendrite growth is a diffusion-controlled process and the atomic diffusion speed is only 2.0 m s −1

  11. Phase stabilization in plasma sprayed BaTiO3

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Seiner, Hanuš; Sedláček, J.; Pala, Zdeněk; Vaněk, Přemysl

    2013-01-01

    Roč. 39, č. 5 (2013), s. 5039-5048 ISSN 0272-8842 R&D Projects: GA ČR(CZ) GA101/09/0702 Institutional support: RVO:61389021 ; RVO:61388998 ; RVO:68378271 Keywords : Spectroscopy * BaTiO3 * Plasma spraying * Spark plasma sintering Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass; BJ - Thermodynamics (UT-L); JH - Ceramics, Fire-Resistant Materials and Glass (FZU-D) Impact factor: 2.086, year: 2013 http://www.sciencedirect.com/science/article/pii/S0272884212013582

  12. New calculation method for thermodynamic properties of humid air in humid air turbine cycle – The general model and solutions for saturated humid air

    International Nuclear Information System (INIS)

    Wang, Zidong; Chen, Hanping; Weng, Shilie

    2013-01-01

    The article proposes a new calculation method for thermodynamic properties (i.e. specific enthalpy, specific entropy and specific volume) of humid air in humid air turbine cycle. The research pressure range is from 0.1 MPa to 5 MPa. The fundamental behaviors of dry air and water vapor in saturated humid air are explored in depth. The new model proposes and verifies the relationship between total gas mixture pressure and gas component pressures. This provides a good explanation of the fundamental behaviors of gas components in gas mixture from a new perspective. Another discovery is that the water vapor component pressure of saturated humid air equals P S , always smaller than its partial pressure (f·P S ) which was believed in the past researches. In the new model, “Local Gas Constant” describes the interaction between similar molecules. “Improvement Factor” is proposed for the first time by this article, and it quantitatively describes the magnitude of interaction between dissimilar molecules. They are combined to fully describe the real thermodynamic properties of humid air. The average error of Revised Dalton's Method is within 0.1% compared to experimentally-based data. - Highlights: • Our new model is suitable to calculate thermodynamic properties of humid air in HAT cycle. • Fundamental behaviors of dry air and water vapor in saturated humid air are explored in depth. • Local-Gas-Constant describes existing alone component and Improvement Factor describes interaction between different components. • The new model proposes and verifies the relationship between total gas mixture pressure and component pressures. • It solves saturated humid air thoroughly and deviates from experimental data less than 0.1%

  13. Chlorination pattern effect on thermodynamic parameters and environmental degradability for C₁₀-SCCPs: Quantum chemical calculation based on virtual combinational library.

    Science.gov (United States)

    Sun, Yuzhen; Pan, Wenxiao; Lin, Yuan; Fu, Jianjie; Zhang, Aiqian

    2016-01-01

    Short-chain chlorinated paraffins (SCCPs) are still controversial candidates for inclusion in the Stockholm Convention. The inherent mixture nature of SCCPs makes it rather difficult to explore their environmental behaviors. A virtual molecule library of 42,720 C10-SCCP congeners covering the full structure spectrum was constructed. We explored the structural effects on the thermodynamic parameters and environmental degradability of C10-SCCPs through semi-empirical quantum chemical calculations. The thermodynamic properties were acquired using the AM1 method, and frontier molecular orbital analysis was carried out to obtain the E(HOMO), E(LUMO) and E(LUMO)-E(HOMO) for degradability exploration at the same level. The influence of the chlorination degree (N(Cl)) on the relative stability and environmental degradation was elucidated. A novel structural descriptor, μ, was proposed to measure the dispersion of the chlorine atoms within a molecule. There were significant correlations between thermodynamic values and N(Cl), while the reported N(Cl)-dependent pollution profile of C10-SCCPs in environmental samples was basically consistent with the predicted order of formation stability of C10-SCCP congeners. In addition, isomers with large μ showed higher relative stability than those with small μ. This could be further verified by the relationship between μ and the reactivity of nucleophilic substitution and OH attack respectively. The C10-SCCP congeners with less Cl substitution and lower dispersion degree are susceptible to environmental degradation via nucleophilic substitution and hydroxyl radical attack, while direct photolysis of C10-SCCP congeners cannot readily occur due to the large E(LUMO)-E(HOMO) values. The chlorination effect and the conclusions were further checked with appropriate density functional theory (DFT) calculations. Copyright © 2015. Published by Elsevier B.V.

  14. Phases stability of shape memory alloys Cu based under irradiation

    International Nuclear Information System (INIS)

    Zelaya, Maria Eugenia

    2006-01-01

    The effects of irradiation on the relative phase stability of phases related by a martensitic transformation in copper based shape memory alloys were studied in this work.Different kind of particles and energies were employed in the irradiation experiments.The first kind of irradiation was performed with 2,6 MeV electrons, the second one with 170 keV and 300 keV Cu ions and the third one with swift heavy ions (Kr, Xe, Au) with energies between 200 and 600 MeV.Stabilization of the 18 R martensite in Cu-Zn-Al-Ni induced by electron irradiation was studied.The results were compared to those of the stabilization induced by quenching and ageing in the same alloy, and the ones obtained by irradiation in 18 R-Cu-Zn-Al alloys.The effects of Cu irradiation over b phase were analyzed with several electron microscopy techniques including: scanning electron microscopy (S E M), high resolution electron microscopy (H R E M), micro diffraction and X-ray energy dispersive spectroscopy (E D S). Structural changes in Cu-Zn-Al b phase into a closed packed structure were induced by Cu ion implantation.The closed packed structures depend on the irradiation fluence.Based on these results, the interface between these structures (closed packed and b) and the stability of disordered phases were analyzed. It was also compared the evolution of long range order in the Cu-Zn-Al and in the Cu-Zn-Al-Ni b phase as a function of fluence.The evolution of the g phase was also compared. Both results were discussed in terms of the mobility of irradiation induced point defects.Finally, the effects induced by swift heavy ions in b phase and 18 R martensite were studied. The results of the irradiation in b phase were qualitatively similar to those produced by irradiation with lower energies. On the contrary, nano metric defects were found in the irradiated 18 R martensite.These defects were characterized by H R E M.The characteristic contrast of the defects was associated to a local change in the

  15. First-principles calculations of dynamical and thermodynamic properties of cuprite doped with silver (Cu2(1‑x)Ag2xO)

    Science.gov (United States)

    Musari, A. A.; Joubert, D. P.; Adebayo, G. A.

    2018-04-01

    Cuprite (Cu2O) is a solid mineral and a compound whose simplicity of preparation, non toxic nature, low band gap and its abundance has made it a prospective candidate for the realisation of low cost photovoltaic applications. The present work successfully dopes Cuprite with Ag ({{{Cu}}}2(1-{{x})}{{{Ag}}}2{{x}}{{O}}) at different concentrations x = 0, 0.25, 0.5, 0.75 and 1, their first-principle calculations of their electronic, dynamical and thermodynamic properties have been investigated extensively within the generalised gradient approximation. Direct band gap energies at {{Γ }} are predicted for all the studied systems. A small bowing parameter for lattice constants ba and bulk modulus bB of 0.4245 \\mathring{{A}} and 0.8747 GPa were obtained when compared to Vegard’s law. The results of phonon dispersion when x = 0 and 1 indicate stability, these agree with available theoretical and experimental results while negative frequencies observed along the Brillouin zone for the doped systems when x = 0.25, 0.5 and 0.75 imply that they are dynamically unstable. The thermodynamic properties between 0 to 800 K were determined using the calculated phonon density of states within the harmonic approximation and the values of the specific heat capacity at constant volume at ambient temperature and the temperature at which lattice vibrations and thermal motion of electrons contribute to the constant volume specific heat capacity are presented for all the systems.

  16. First-Principle Calculations for Thermodynamic Properties of LiBC Under High Temperature and High Pressure

    Institute of Scientific and Technical Information of China (English)

    LIU Zhong-Li; CHENG Yan; TAN Ni-Na; GOU Qing-Quan

    2006-01-01

    The thermodynamic properties of LiBC are investigated by using the full-potential linearized muffin-tin orbital method (FP-LMTO) within the frame of density functional theory (DFT) and using the quasi-harmonic Debye model. The dependencies of the normalized lattice parameters a/a0 and c/c0, the ratio (c/a)/2, the normalized primitive volume V/V0 on pressure and temperature are successfully obtained. It is found that the interlayer covalent interactions (Li-B bonds or Li-C bonds) are more sensitive to temperature and pressure than intralayer ones (B-C bonds), as gives rise to the extreme lattice anisotropy in the bulk hcp LiBC.

  17. Use of thermodynamic calculation for investigating phase diagram of the ternary system NaCl-PbCl2-NdCl3

    International Nuclear Information System (INIS)

    Kostygov, V.I.; Potemin, S.S.

    1984-01-01

    Thermodynamic calculation of meltability diagram of ternary system NaCl-PbCl 2 -NdCl 3 with the use of literature and experimental data on meltability diagrams of binary systems forming it, as well as data on crystallization heats of the components, has been carried out. Equations are derived under condition of pseudoperfection of the ternary system. 64 mol.% PbCl 2 , 26 mol.% NaCl, 10 mol.% NdCl 3 and average temperature of crystallization 391 deg C correspond to the calculated composition of the ternary eutectics, 49 mol.% PbCl 2 , 35 mol.% NaCl, 16 mol.% NdCl 3 and average temperature of peritectic transformation 416 deg C - to the composition of the ternary peritectic. The results obtained agree well with the experimental data

  18. The calculated magnetic, electronic and thermodynamic properties of Ce{sub 3}Co{sub 29}Si{sub 4}B{sub 10} compound

    Energy Technology Data Exchange (ETDEWEB)

    Huo, Jin-Rong [Institute of Applied Physics, Beijing University of Science and Technology, Beijing 100083 (China); Wang, Xiao-Xu [Institute of Applied Physics, Beijing University of Science and Technology, Beijing 100083 (China); Cloud Computing Department, Beijing Computing Center, Beijing 100084 (China); Hu, Yao-Wen [Department of Physics, Tsinghua University, Beijing 100084 (China); Zhang, Guo-Hua; Cheng, Hai-Xia; Li, Lu [Institute of Applied Physics, Beijing University of Science and Technology, Beijing 100083 (China); Qian, Ping, E-mail: qianping@ustb.edu.cn [Institute of Applied Physics, Beijing University of Science and Technology, Beijing 100083 (China)

    2016-05-15

    The magnetic moment, lattice parameter and atom fraction coordinates for Ce{sub 3}Co{sub 29}Si{sub 4}B{sub 10} are calculated by the first-principles GGA+U method, and the results indicate that the calculated and experimental values are basically accordant when U=2.6 eV. We study the interaction effect and orbital hybridization between Co and Ce atoms. The projected density of states at U=2.6 eV which provided by Co-2c, Ce-2b and Ce-4d sites are contrasted with else U values. Meanwhile the electron density of states for different sites and the distance between various atoms are exhibited. In addition, the thermodynamic properties of Ce{sub 3}Co{sub 29}Si{sub 4}B{sub 10} are evaluated by using a series of interatomic pair potentials. - Graphical abstract: Change of the total magnetic moment for Ce{sub 3}Co{sub 29}Si{sub 4}B{sub 10} along with the value of U. There is a sharply decline of the curve at U=2.6 eV and, at the moment, the total magnetic moment of the compound have a good agreement with the experimental data. - Highlights: • We research of quaternary rare earth and transition metal compounds. • We perform the calculation of magnetic moment and electronic structure by GGA+U method. • The orbital hybridization between Co and Ce atoms is displayed and analyzed. • Show the plot of projected density of states for different sites more clearly. • Calculate the thermodynamic property of rare-earth transition metal compound.

  19. Ab initio study of effects of substitutional additives on the phase stability of γ-alumina

    International Nuclear Information System (INIS)

    Jiang Kaiyun; Music, Denis; Sarakinos, Kostas; Schneider, Jochen M

    2010-01-01

    Using ab initio calculations, we have evaluated two structural descriptions of γ-Al 2 O 3 , spinel and tetragonal hausmannite, and explored the relative stability of γ-Al 2 O 3 with respect to α-Al 2 O 3 with 2.5 at.% of Si, Cr, Ti, Sc, and Y additives to identify alloying element induced electronic structure changes that impede the γ to α transition. The total energy calculations indicate that Si stabilizes γ-Al 2 O 3 , while Cr stabilizes α-Al 2 O 3 . As Si is added, a bond length increase in α-Al 2 O 3 is observed, while strong and short Si-O bonds are formed in γ-Al 2 O 3 , consequently stabilizing this phase. On the other hand, Cr additions induce a smaller bond length increase in α-Al 2 O 3 than in γ-Al 2 O 3 , therefore stabilizing the α-phase. The bulk moduli of γ-Al 2 O 3 with these additives show no significant changes. The phase stability and elastic property data discussed here underline the application potential of Si alloyed γ-Al 2 O 3 for applications at elevated temperatures. Furthermore it is evident that the tetragonal hausmannite structure is a suitable description for γ-Al 2 O 3 .

  20. Lattice dynamics, thermodynamics and elastic properties of C22-Zr{sub 6}FeSn{sub 2} from first-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Xuan-Kai [School of Materials Science and Engineering, Shanghai University, Shanghai 200444 (China); Shi, Siqi, E-mail: sqshi@shu.edu.cn [School of Materials Science and Engineering, Shanghai University, Shanghai 200444 (China); Materials Genome Institute, Shanghai University, Shanghai 200444 (China); Shen, Jian-Yun [General Research Institute for Nonferrous Metals, Beijing 100088 (China); Shang, Shun-Li [Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Yao, Mei-Yi, E-mail: yaomeiyi@shu.edu.cn [School of Materials Science and Engineering, Shanghai University, Shanghai 200444 (China); Liu, Zi-Kui [Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802 (United States)

    2016-10-15

    Since Zr-Fe-Sn is one of the key ternary systems for cladding and structural materials in nuclear industry, it is of significant importance to understand physicochemical properties related to Zr-Fe-Sn system. In order to design the new Zr alloys with advanced performance by CALPHAD method, the thermodynamic model for the lower order systems is required. In the present work, first-principles calculations are employed to obtain phonon, thermodynamic and elastic properties of Zr{sub 6}FeSn{sub 2} with C22 structure and the end-members (C22-Zr{sub 6}FeFe{sub 2}, C22-Zr{sub 6}SnSn{sub 2} and C22-Zr{sub 6}SnFe{sub 2}) in the model of (Zr){sub 6}(Fe, Sn){sub 2}(Fe, Sn){sub 1}. It is found that the imaginary phonon modes are absent for C22-Zr{sub 6}FeSn{sub 2} and C22-Zr{sub 6}SnSn{sub 2}, indicating they are dynamically stable, while the other two end-members are unstable. Gibbs energies of C22-Zr{sub 6}FeSn{sub 2} and C22-Zr{sub 6}SnSn{sub 2} are obtained from the quasiharmonic phonon approach and can be added in the thermodynamic database: Nuclearbase. The C22-Zr{sub 6}FeSn{sub 2}’s single-crystal elasticity tensor components along with polycrystalline bulk, shear and Young’s moduli are computed with a least-squares approach based upon the stress tensor computed from first-principles method. The results indicate that distortion is more difficult in the directions normal the c-axis than along to it.

  1. Carbohydrates in thermophile metabolism: calculation of the standard molal thermodynamic properties of aqueous pentoses and hexoses at elevated temperatures and pressures

    Science.gov (United States)

    Amend, Jan P.; Plyasunov, Andrey V.

    2001-11-01

    Experimental thermodynamic data for aqueous organic compounds can be combined with the revised Helgeson-Kirkham-Flowers (HKF) equations of state to generate parameters that can be used to estimate standard molal properties as functions of temperature and pressure. In this study, we regressed thermodynamic data for aqueous carbohydrates at temperatures up to 393 K reported in the literature to permit the calculation of the apparent standard molal Gibbs free energies and enthalpies of formation (ΔGo and ΔHo, respectively) and the standard molal entropies (S2o), heat capacities (CP,2o), and volumes (V2o) to 423 K and several hundred MPa of aqueous C5 aldoses (ribose, arabinose, xylose, lyxose) and C5 ketoses (ribulose, xylulose) as well as C6 aldoses (glucose, mannose, galactose) and C6 ketoses (fructose, sorbose). Values of ΔGo for these 11 aqueous carbohydrates are given as a function of temperature at the saturated water vapor pressure (PSAT) and at 50 MPa. Values of ΔGo for aqueous glucose are then combined with those of other aqueous organic and inorganic compounds to calculate values of the standard molal Gibbs free energies of 13 fermentation and respiration reactions (ΔGro) known or likely to be carried out by thermophilic microorganisms. Finally, values of the overall Gibbs free energies of these reactions (ΔGr) are calculated at the temperature, pressure, and chemical composition that obtain in the hydrothermal fluids of Vulcano Island, southern Italy, a site that is widely known for its tremendous diversity of organisms able to live at high temperatures. At likely activities of aqueous glucose, it is shown that thermophiles in the hot springs of Vulcano at 373 K and ∼0.1 MPa can gain between 400 and 3000 kJ per mole of glucose fermented or respired.

  2. Comparative first-principles calculations of the electronic, optical, elastic and thermodynamic properties of XCaF{sub 3} (X = K, Rb, Cs) cubic perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Li, Li; Wang, Y.-J. [College of Mathematics and Physics, Chongqing University of Posts and Telecommunications, 2 Chongwen Road, Nan' an District, Chongqing 400065 (China); Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland); Liu, D.-X.; Ma, C.-G. [College of Mathematics and Physics, Chongqing University of Posts and Telecommunications, 2 Chongwen Road, Nan' an District, Chongqing 400065 (China); Brik, M.G., E-mail: mikhail.brik@ut.ee [College of Mathematics and Physics, Chongqing University of Posts and Telecommunications, 2 Chongwen Road, Nan' an District, Chongqing 400065 (China); Institute of Physics, University of Tartu, W. Ostwald Str. 1, Tartu 50411 (Estonia); Institute of Physics, Jan Długosz University, Armii Krajowej 13/15, PL-42200 Częstochowa (Poland); Suchocki, A. [College of Mathematics and Physics, Chongqing University of Posts and Telecommunications, 2 Chongwen Road, Nan' an District, Chongqing 400065 (China); Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland); Institute of Physics, Kazimierz Wielki University, Weyssenhoffa 11, 85-072 Bydgoszcz (Poland); Piasecki, M. [Institute of Physics, Jan Długosz University, Armii Krajowej 13/15, PL-42200 Częstochowa (Poland); Reshak, A.H. [New Technologies – Research Centre, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic); School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia)

    2017-02-15

    Three fluoroperovskites with the general formula XCaF{sub 3} (X = K, Rb, Cs) have been systematically studied using the first-principles methods. The structural, electronic, optical, elastic and thermodynamic properties of these three compounds were calculated at the ambient and elevated hydrostatic pressure. Variation of all these properties with pressure was analyzed; it was shown that the structural and elastic constants change linearly with increased pressure, whereas the calculated band gaps follow the quadratic dependence on pressure. Influence of the first cation variation (K – Rb – Cs) on these properties was discussed. Elastic anisotropy (directional dependence of the Young moduli) of these compounds was modeled and analyzed for the first time. - Highlights: • Three cubic perovskites XCaF{sub 3} (X = K, Rb, Cs) were studied by ab initio methods. • Systematic variation of physical properties with the first cation change was traced. • Pressure effects on physical properties were calculated and modeled. • Debye temperature and Grüneisen constant for all materials were calculated for the first time. • Elastic anisotropy was visualized by plotting Young moduli directional dependences.

  3. First -principles calculations of the crystal structure, electronic structure, and thermodynamic stability of Be(BH4)2

    NARCIS (Netherlands)

    van Setten, Michiel J.; de Wijs, Gilles A.; Brocks, G.

    2008-01-01

    Alanates and boranates are intensively studied because of their potential use as hydrogen storage materials. In this paper, we present a first-principles study of the electronic structure and the energetics of beryllium boranate BeBH42. From total energy calculations, we show that—in contrast to the

  4. Preparation of Zr50Al15-xNi10Cu25Yx amorphous powders by mechanical alloying and thermodynamic calculation

    International Nuclear Information System (INIS)

    Long, Woyun; Li, Jing; Lu, Anxian

    2013-01-01

    Amorphous Zr 50 Al 15-x Ni 10 Cu 25 Y x powders were fabricated by mechanical alloying at a low rotation speed from commercial pure element powders. The beneficial effect of Al partially substituted by Y in Zr 50 Al 15 Ni 10 Cu 25 on glass-forming ability was investigated. The as-milled powders were characterized by X-ray diffraction and transmission electron microscopy. The results show that partial substitution of Al by Y can improve the glass-forming ability of Zr 50 Al 15 Ni 10 Cu 25 Y alloy. Thermodynamic calculation of equivalent free energy shows that Zr 50 Al 13.8 Ni 10 Cu 25 Y 1.2 alloy has the highest glass-forming ability, which is in good agreement with the report of orthogonal experiments. (author)

  5. Ab initio atomistic thermodynamics calculations of the initial deposition of epitaxial MgO film on GaAs(001)-{beta}2(2 Multiplication-Sign 4)

    Energy Technology Data Exchange (ETDEWEB)

    Tamarany, Rizcky; Lee, Seung-Cheol [Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Department of Nanomaterials Science and Engineering, University of Science and Technology, Daejeon 305-350 (Korea, Republic of); Kim, Hyung-Jun; Choi, Jung-Hae [Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of)

    2013-02-07

    Ab initio calculations were performed to investigate the initial deposition of epitaxial MgO on GaAs(001)-{beta}2(2 Multiplication-Sign 4). The differences between the chemical bonding of Mg-As and O-As were characterized by the adsorption energies of atomic O and Mg at several symmetrically distinct sites, and O bonding was substantially stronger than that of Mg. Thermodynamics were analyzed through the introduction of environmental chemical potentials simulating in situ growth conditions by the sputtering of a stoichiometric MgO target. A surface phase diagram was generated under Mg and O environments with constrained equilibrium, and the results explained the initial formation of an epitaxial MgO phase on GaAs(001)-{beta}2(2 Multiplication-Sign 4).

  6. Ab initio atomistic thermodynamics calculations of the initial deposition of epitaxial MgO film on GaAs(001)-β2(2 × 4)

    International Nuclear Information System (INIS)

    Tamarany, Rizcky; Lee, Seung-Cheol; Kim, Hyung-Jun; Choi, Jung-Hae

    2013-01-01

    Ab initio calculations were performed to investigate the initial deposition of epitaxial MgO on GaAs(001)-β2(2 × 4). The differences between the chemical bonding of Mg-As and O-As were characterized by the adsorption energies of atomic O and Mg at several symmetrically distinct sites, and O bonding was substantially stronger than that of Mg. Thermodynamics were analyzed through the introduction of environmental chemical potentials simulating in situ growth conditions by the sputtering of a stoichiometric MgO target. A surface phase diagram was generated under Mg and O environments with constrained equilibrium, and the results explained the initial formation of an epitaxial MgO phase on GaAs(001)-β2(2 × 4).

  7. The Effect of Indium Concentration on the Structure and Properties of Zirconium Based Intermetallics: First-Principles Calculations

    Directory of Open Access Journals (Sweden)

    Fuda Guo

    2016-01-01

    Full Text Available The phase stability, mechanical, electronic, and thermodynamic properties of In-Zr compounds have been explored using the first-principles calculation based on density functional theory (DFT. The calculated formation enthalpies show that these compounds are all thermodynamically stable. Information on electronic structure indicates that they possess metallic characteristics and there is a common hybridization between In-p and Zr-d states near the Fermi level. Elastic properties have been taken into consideration. The calculated results on the ratio of the bulk to shear modulus (B/G validate that InZr3 has the strongest deformation resistance. The increase of indium content results in the breakout of a linear decrease of the bulk modulus and Young’s modulus. The calculated theoretical hardness of α-In3Zr is higher than the other In-Zr compounds.

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

    International Nuclear Information System (INIS)

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

    2001-01-01

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

  9. Simplified calculation of nonlocal thermodynamic equilibrium excited state populations contributing to 13.5 nm emission in a tin plasma

    International Nuclear Information System (INIS)

    White, J.; Cummings, A.; Dunne, P.; Hayden, P.; O'Sullivan, G.

    2007-01-01

    Extreme ultraviolet lithography schemes for the semiconductor industry are currently based on coupling radiation from a plasma source into a 2% bandwidth at 13.5 nm (91.8 eV). In this paper, we consider the case for a laser-produced plasma (LPP) and address the calculation of ionic level populations in the 4p 6 4d N , 4p 6 4d N-1 4f 1 , 4p 5 4d N+1 , and 4p 6 4d N-1 5p 1 configurations in a range of tin ions (Sn 6+ to Sn 13+ ) producing radiation in this bandwidth. The LPP is modeled using a one-dimensional hydrodynamics code, which uses a hydrogenic, average atom model, where the level populations are treated as l degenerate. Hartree-Fock calculations are used to remove the l degeneracy and an energy functional method to calculate the nl level populations involved in n=4-4 transitions as a function of distance from the target surface and time. Detailed data are presented for the tin ions that contribute to in-band emission

  10. Suggestion of typical phases of in-vessel fuel-debris by thermodynamic calculation for decommissioning technology of Fukushima-Daiichi nuclear power station

    Energy Technology Data Exchange (ETDEWEB)

    Ikeuchi, Hirotomo; Yano, Kimihiko; Kaji, Naoya; Washiya, Tadahiro [Japan Atomic Energy Agency, 4-33 Muramatsu, Tokai-mura, Ibaraki-ken, 319-1194 (Japan); Kondo, Yoshikazu; Noguchi, Yoshikazu [PESCO Co.Ltd. (Korea, Republic of)

    2013-07-01

    For the decommissioning of the Fukushima-Daiichi Nuclear Power Station (1F), the characterization of fuel-debris in cores of Units 1-3 is necessary. In this study, typical phases of the in-vessel fuel-debris were estimated using a thermodynamic equilibrium (TDE) calculation. The FactSage program and NUCLEA database were applied to estimate the phase equilibria of debris. It was confirmed that the TDE calculation using the database can reproduce the phase separation behavior of debris observed in the Three Mile Island accident. In the TDE calculation of 1F, the oxygen potential [G(O{sub 2})] was assumed to be a variable. At low G(O{sub 2}) where metallic zirconium remains, (U,Zr)O{sub 2}, UO{sub 2}, and ZrO{sub 2} were found as oxides, and oxygen-dispersed Zr, Fe{sub 2}(Zr,U), and Fe{sub 3}UZr{sub 2} were found as metals. With an increase in zirconium oxidation, the mass of those metals, especially Fe{sub 3}UZr{sub 2}, decreased, but the other phases of metals hardly changed qualitatively. Consequently, (U,Zr)O{sub 2} is suggested as a typical phase of oxide, and Fe{sub 2}(Zr,U) is suggested as that of metal. However, a more detailed estimation is necessary to consider the distribution of Fe in the reactor pressure vessel through core-melt progression. (authors)

  11. The influence of glass composition on crystalline phase stability in glass-ceramic wasteforms

    International Nuclear Information System (INIS)

    Maddrell, Ewan; Thornber, Stephanie; Hyatt, Neil C.

    2015-01-01

    Highlights: • Crystalline phase formation shown to depend on glass matrix composition. • Zirconolite forms as the sole crystalline phase only for most aluminous glasses. • Thermodynamics indicate that low silica activity glasses stabilise zirconolite. - Abstract: Zirconolite glass-ceramic wasteforms were prepared using a suite of Na 2 O–Al 2 O 3 –B 2 O 3 –SiO 2 glass matrices with variable Al:B ratios. Zirconolite was the dominant crystalline phase only for the most alumina rich glass compositions. As the Al:B ratio decreased zirconolite was replaced by sphene, zircon and rutile. Thermodynamic data were used to calculate a silica activity in the glass melt below which zirconolite is the favoured crystalline phase. The concept of the crystalline reference state of glass melts is then utilised to provide a physical basis for why silica activity varies with the Al:B ratio

  12. 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.

  13. Theoretical calculation of reorganization energy for electron self-exchange reaction by constrained density functional theory and constrained equilibrium thermodynamics.

    Science.gov (United States)

    Ren, Hai-Sheng; Ming, Mei-Jun; Ma, Jian-Yi; Li, Xiang-Yuan

    2013-08-22

    Within the framework of constrained density functional theory (CDFT), the diabatic or charge localized states of electron transfer (ET) have been constructed. Based on the diabatic states, inner reorganization energy λin has been directly calculated. For solvent reorganization energy λs, a novel and reasonable nonequilibrium solvation model is established by introducing a constrained equilibrium manipulation, and a new expression of λs has been formulated. It is found that λs is actually the cost of maintaining the residual polarization, which equilibrates with the extra electric field. On the basis of diabatic states constructed by CDFT, a numerical algorithm using the new formulations with the dielectric polarizable continuum model (D-PCM) has been implemented. As typical test cases, self-exchange ET reactions between tetracyanoethylene (TCNE) and tetrathiafulvalene (TTF) and their corresponding ionic radicals in acetonitrile are investigated. The calculated reorganization energies λ are 7293 cm(-1) for TCNE/TCNE(-) and 5939 cm(-1) for TTF/TTF(+) reactions, agreeing well with available experimental results of 7250 cm(-1) and 5810 cm(-1), respectively.

  14. Measuring laves phase particle size and thermodynamic calculating its growth and coarsening behavior in P92 steels

    DEFF Research Database (Denmark)

    Yao, Bing-Yin; Zhou, Rong-Can; Fan, Chang-Xin

    2010-01-01

    The growth of Laves phase particles in three kinds of P92 steels were investigated. Laves phase particles can be easily separated and distinguished from the matrix and other particles by atom number contrast using comparisons of the backscatter electrons (BSE) images and the secondary electrons (SE......) images in scanning electron microscope (SEM). The smaller Laves phase particle size results in higher creep strength and longer creep exposure time at the same conditions. DICTRA software was used to model the growth and coarsening behavior of Laves phase in the three P92 steels. Good agreements were...... attained between measurements in SEM and modeling by DICTRA. Ostwald ripening should be used for the coarsening calculation of Laves phase in P92 steels for time longer than 20000 h and 50000 h at 650°C and 600°C, respectively. © 2010 Chin. Soc. for Elec. Eng....

  15. Quantum chemical calculations and spectroscopic measurements of spectroscopic and thermodynamic properties of given uranyl complexes in aqueous solutions with possible environmental and industrial applications

    Directory of Open Access Journals (Sweden)

    Višňak Jakub

    2016-01-01

    Full Text Available A brief introduction into computational methodology and preliminary results for spectroscopic (excitation energies, vibrational frequencies in ground and excited electronic states and thermodynamic (stability constants, standard enthalpies and entropies of complexation reactions properties of some 1:1, 1:2 and 1:3 uranyl sulphato- and selenato- complexes in aqueos solutions will be given. The relativistic effects are included via Effective Core Potential (ECP, electron correlation via (TDDFT/B3LYP (dispersion interaction corrected and solvation is described via explicit inclusion of one hydration sphere beyond the coordinated water molecules. We acknowledge limits of this approximate description – more accurate calculations (ranging from semi-phenomenological two-component spin-orbit coupling up to four-component Dirac-Coulomb-Breit hamiltonian and Molecular Dynamics simulations are in preparation. The computational results are compared with the experimental results from Time-resolved Laser-induced Fluorescence Spectroscopy (TRLFS and UV-VIS spectroscopic studies (including our original experimental research on this topic. In case of the TRLFS and UV-VIS speciation studies, the problem of complex solution spectra decomposition into individual components is ill-conditioned and hints from theoretical chemistry could be very important. Qualitative agreement between our quantum chemical calculations of the spectroscopic properties and experimental data was achieved. Possible applications for geochemical modelling (e.g. safety studies of nuclear waste repositories, modelling of a future mining site and analytical chemical studies (including natural samples are discussed.

  16. Phase stability of AlYB14 sputtered thin films

    International Nuclear Information System (INIS)

    Koelpin, Helmut; Music, Denis; Emmerlich, Jens; Schneider, Jochen M; Henkelman, Graeme; Munnik, Frans

    2009-01-01

    AlYB 14 (Imma) thin films were synthesized by magnetron sputtering. On the basis of x-ray diffraction, no phases other than crystalline AlYB 14 could be identified. According to electron probe microanalysis, energy dispersive x-ray analysis and elastic recoil detection analysis, the Al and Y occupancies vary in the range of 0.73-1.0 and 0.29-0.45, respectively. Density functional theory based calculations were carried out to investigate the effect of occupancy on the stability of Al x Y y B 14 (x,y = 0.25, 0.5, 0.75, 1). The mean effective charge per icosahedron and the bulk moduli were also calculated. It is shown that the most stable configuration is Al 0.5 YB 14 , corresponding to a charge transfer of two electrons from the metal atoms to the boron icosahedra. Furthermore, it is found that the stability of a configuration is increased as the charge is homogeneously distributed within the icosahedra. The bulk moduli for all configurations investigated are in the range between 196 and 220 GPa, rather close to those for known hard phases such as α- Al 2 O 3 .

  17. Improved modification for the density-functional theory calculation of thermodynamic properties for C-H-O composite compounds.

    Science.gov (United States)

    Liu, Min Hsien; Chen, Cheng; Hong, Yaw Shun

    2005-02-08

    A three-parametric modification equation and the least-squares approach are adopted to calibrating hybrid density-functional theory energies of C(1)-C(10) straight-chain aldehydes, alcohols, and alkoxides to accurate enthalpies of formation DeltaH(f) and Gibbs free energies of formation DeltaG(f), respectively. All calculated energies of the C-H-O composite compounds were obtained based on B3LYP6-311++G(3df,2pd) single-point energies and the related thermal corrections of B3LYP6-31G(d,p) optimized geometries. This investigation revealed that all compounds had 0.05% average absolute relative error (ARE) for the atomization energies, with mean value of absolute error (MAE) of just 2.1 kJ/mol (0.5 kcal/mol) for the DeltaH(f) and 2.4 kJ/mol (0.6 kcal/mol) for the DeltaG(f) of formation.

  18. Basic Thermodynamics

    International Nuclear Information System (INIS)

    Duthil, P

    2014-01-01

    The goal of this paper is to present a general thermodynamic basis that is useable in the context of superconductivity and particle accelerators. The first part recalls the purpose of thermodynamics and summarizes its important concepts. Some applications, from cryogenics to magnetic systems, are covered. In the context of basic thermodynamics, only thermodynamic equilibrium is considered

  19. Basic Thermodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Duthil, P [Orsay, IPN (France)

    2014-07-01

    The goal of this paper is to present a general thermodynamic basis that is useable in the context of superconductivity and particle accelerators. The first part recalls the purpose of thermodynamics and summarizes its important concepts. Some applications, from cryogenics to magnetic systems, are covered. In the context of basic thermodynamics, only thermodynamic equilibrium is considered.

  20. Elements of chemical thermodynamics

    CERN Document Server

    Nash, Leonard K

    2005-01-01

    This survey of purely thermal data in calculating the position of equilibrium in a chemical reaction highlights the physical content of thermodynamics, as distinct from purely mathematical aspects. 1970 edition.

  1. Phase Stability and Elasticity of TiAlN

    Directory of Open Access Journals (Sweden)

    Magnus Odén

    2011-09-01

    Full Text Available We review results of recent combined theoretical and experimental studies of Ti1−xAlxN, an archetypical alloy system material for hard-coating applications. Theoretical simulations of lattice parameters, mixing enthalpies, and elastic properties are presented. Calculated phase diagrams at ambient pressure, as well as at pressure of 10 GPa, show a wide miscibility gap and broad region of compositions and temperatures where the spinodal decomposition takes place. The strong dependence of the elastic properties and sound wave anisotropy on the Al-content offers detailed understanding of the spinodal decomposition and age hardening in Ti1−xAlxN alloy films and multilayers. TiAlN/TiN multilayers can further improve the hardness and thermal stability compared to TiAlN since they offer means to influence the kinetics of the favorable spinodal decomposition and suppress the detrimental transformation to w-AlN. Here, we show that a 100 degree improvement in terms of w-AlN suppression can be achieved, which is of importance when the coating is used as a protective coating on metal cutting inserts.

  2. Statistical thermodynamics

    International Nuclear Information System (INIS)

    Lim, Gyeong Hui

    2008-03-01

    This book consists of 15 chapters, which are basic conception and meaning of statistical thermodynamics, Maxwell-Boltzmann's statistics, ensemble, thermodynamics function and fluctuation, statistical dynamics with independent particle system, ideal molecular system, chemical equilibrium and chemical reaction rate in ideal gas mixture, classical statistical thermodynamics, ideal lattice model, lattice statistics and nonideal lattice model, imperfect gas theory on liquid, theory on solution, statistical thermodynamics of interface, statistical thermodynamics of a high molecule system and quantum statistics

  3. Electron concentration and phase stability in NbCr2-based Laves phase alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, J.H.; Liaw, P.K. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering; Liu, C.T. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

    1997-05-12

    Phase stability in NbCr{sub 2}-based transition-metal Laves phases was studied, based on the data reported for binary X-Cr, Nb-X, and ternary Nb-Cr-X phase diagrams. It was shown that when the atomic size ratios are kept identical, the average electron concentration factor, e/a, is the dominating factor in controlling the phase stability of NbCr{sub 2}-based transition-metal Laves phases. The e/a ratios for different Laves polytypes were determined as followed: with e/a < 5.76, the C15 structure is stabilized; at an e/a range of 5.88--7.53, the C14 structure is stabilized; with e/a > 7.65, the C15 structure is stabilized again. A further increase in the electron concentration factor (e/a > 8) leads to the disordering of the alloy. The electron concentration effect on the phase stability of Mg-based Laves phases and transition-metal A{sub 3}B intermetallic compounds is also reviewed and compared with the present observations in transition-metal Laves phases. In order to verify the e/a/phase stability relationship experimentally, additions of Cu (with e/a = 11) were selected to replace Cr in the NbCr{sub 2} Laves phase. Experimental results for the ternary Nb-Cr-Cu system are reported and discussed in terms of the correlation between the e/a ratio and phase stability in NbCr{sub 2}-based Laves phases. A new phase was found, which has an average composition of Nb-47Cr-3Cu. Within the solubility limit, the electron concentration and phase stability relationship is obeyed in the Nb-Cr-Cu system.

  4. Magnetically induced crystal structure and phase stability in Fe1-cCoc

    DEFF Research Database (Denmark)

    Abrikosov, I.A.; James, P.; Eriksson, O.

    1996-01-01

    We present an ab initio determination of the crystallographic phase stability of Fe-Co alloys as a function of concentration, using the coherent potential approximation. A bcc --> hcp phase transition is found at a concentration of 85 at.% of Co, in good agreement with the experimental phase...... diagram. We demonstrate that for the Pe-rich random alloys magnetism-stabilizes the bce phase relative to the close-packed fee and hcp phases. Magnetism also favors the partially ordered alpha' phase relative to the random bce alloy. This unique relation between magnetism and phase stability for the Fe...

  5. Phase stability limit of c-BN under hydrostatic and non-hydrostatic pressure conditions

    International Nuclear Information System (INIS)

    Xiao, Jianwei; Du, Jinglian; Wen, Bin; Zhang, Xiangyi; Melnik, Roderick; Kawazoe, Yoshiyuki

    2014-01-01

    Phase stability limit of cubic boron nitride (c-BN) has been investigated by the crystal structure search technique. It indicated that this limit is ∼1000 GPa at hydrostatic pressure condition. Above this pressure, c-BN turns into a metastable phase with respect to rocksalt type boron nitride (rs-BN). However, rs-BN cannot be retained at 0 GPa owing to its instability at pressure below 250 GPa. For non-hydrostatic pressure conditions, the phase stability limit of c-BN is substantially lower than that under hydrostatic pressure conditions and it is also dramatically different for other pressure mode

  6. Development of Bi-base high-temperature Pb-free solders with second-phase dispersion: Thermodynamic calculation, microstructure, and interfacial reaction

    Science.gov (United States)

    Takaku, Yoshikazu; Ohnuma, Ikuo; Kainuma, Ryosuke; Yamada, Yasushi; Yagi, Yuji; Nishibe, Yuji; Ishida, Kiyohito

    2006-11-01

    Bismuth and its alloys are candidates for Pb-free high-temperature solders that can be substituted for conventional Pb-rich Pb-Sn solders (melting point (mp) = 573 583 K). However, inferior properties such as brittleness and weak bonding strength should be improved for practical use. To that end, BiCu-X (X=Sb, Sn, and Zn) Pb-free high-temperature solders are proposed. Miscibility gaps in liquid BiCu-X alloys were surveyed using the thermodynamic database ADAMIS (alloy database for micro-solders), and compositions of the BiCu-X solders were designed on the basis of calculation. In-situ composite solders that consist of a Bi-base matrix with fine intermetallic compound (IMC) particles were produced by gas-atomizing and melt-spinning methods. The interfacial reaction between in-situ composite solders and Cu or Ni substrates was investigated. The IMCs at the interface formed a thin, uniform layer, which is an appropriate morphology for a reliable solder joint.

  7. Improvements in X-band transmitter phase stability through Klystron body temperature regulation

    Science.gov (United States)

    Perez, R. M.

    1992-01-01

    This article describes the techniques used and experimental results obtained in improving transmitter stability by control of the klystron body temperature. Related work in the measurement of klystron phase control parameters (pushing factors) is also discussed. The contribution of wave guide temperature excursions to uplink phase stability is presented. Suggestions are made as to the direction of future work in this area.

  8. 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

  9. Generalization of Gibbs Entropy and Thermodynamic Relation

    OpenAIRE

    Park, Jun Chul

    2010-01-01

    In this paper, we extend Gibbs's approach of quasi-equilibrium thermodynamic processes, and calculate the microscopic expression of entropy for general non-equilibrium thermodynamic processes. Also, we analyze the formal structure of thermodynamic relation in non-equilibrium thermodynamic processes.

  10. Thermodynamics of quantum strings

    CERN Document Server

    Morgan, M J

    1994-01-01

    A statistical mechanical analysis of an ideal gas of non-relativistic quantum strings is presented, in which the thermodynamic properties of the string gas are calculated from a canonical partition function. This toy model enables students to gain insight into the thermodynamics of a simple 'quantum field' theory, and provides a useful pedagogical introduction to the more complicated relativistic string theories. A review is also given of the thermodynamics of the open bosonic string gas and the type I (open) superstring gas. (author)

  11. Microsoft excel spreadsheets for calculation of P-V-T relations and thermodynamic properties from equations of state of MgO, diamond and nine metals as pressure markers in high-pressure and high-temperature experiments

    Science.gov (United States)

    Sokolova, Tatiana S.; Dorogokupets, Peter I.; Dymshits, Anna M.; Danilov, Boris S.; Litasov, Konstantin D.

    2016-09-01

    We present Microsoft Excel spreadsheets for calculation of thermodynamic functions and P-V-T properties of MgO, diamond and 9 metals, Al, Cu, Ag, Au, Pt, Nb, Ta, Mo, and W, depending on temperature and volume or temperature and pressure. The spreadsheets include the most common pressure markers used in in situ experiments with diamond anvil cell and multianvil techniques. The calculations are based on the equation of state formalism via the Helmholtz free energy. The program was developed using Visual Basic for Applications in Microsoft Excel and is a time-efficient tool to evaluate volume, pressure and other thermodynamic functions using T-P and T-V data only as input parameters. This application is aimed to solve practical issues of high pressure experiments in geosciences and mineral physics.

  12. Thermodynamic estimation: Ionic materials

    International Nuclear Information System (INIS)

    Glasser, Leslie

    2013-01-01

    Thermodynamics establishes equilibrium relations among thermodynamic parameters (“properties”) and delineates the effects of variation of the thermodynamic functions (typically temperature and pressure) on those parameters. However, classical thermodynamics does not provide values for the necessary thermodynamic properties, which must be established by extra-thermodynamic means such as experiment, theoretical calculation, or empirical estimation. While many values may be found in the numerous collected tables in the literature, these are necessarily incomplete because either the experimental measurements have not been made or the materials may be hypothetical. The current paper presents a number of simple and relible estimation methods for thermodynamic properties, principally for ionic materials. The results may also be used as a check for obvious errors in published values. The estimation methods described are typically based on addition of properties of individual ions, or sums of properties of neutral ion groups (such as “double” salts, in the Simple Salt Approximation), or based upon correlations such as with formula unit volumes (Volume-Based Thermodynamics). - Graphical abstract: Thermodynamic properties of ionic materials may be readily estimated by summation of the properties of individual ions, by summation of the properties of ‘double salts’, and by correlation with formula volume. Such estimates may fill gaps in the literature, and may also be used as checks of published values. This simplicity arises from exploitation of the fact that repulsive energy terms are of short range and very similar across materials, while coulombic interactions provide a very large component of the attractive energy in ionic systems. Display Omitted - Highlights: • Estimation methods for thermodynamic properties of ionic materials are introduced. • Methods are based on summation of single ions, multiple salts, and correlations. • Heat capacity, entropy

  13. Microstructure and phase stability of W-Cr alloy prepared by spark plasma sintering

    Czech Academy of Sciences Publication Activity Database

    Vilémová, Monika; Illková, Ksenia; Lukáč, František; Matějíček, Jiří; Klečka, Jakub; Leitner, J.

    2018-01-01

    Roč. 127, February (2018), s. 173-178 ISSN 0920-3796 R&D Projects: GA ČR(CZ) GA17-23964S Institutional support: RVO:61389021 Keywords : Tungsten-chromium alloy * Phase stability * Decomposition * Thermal conductivity * Self-passivating alloys * Spark plasma sintering Subject RIV: JJ - Other Materials OBOR OECD: Materials engineering Impact factor: 1.319, year: 2016 https://www.sciencedirect.com/science/article/pii/S092037961830005X

  14. Structure and phase stability of a Pu-0.32 wt% Ga alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wheeler, D.W., E-mail: David.Wheeler@awe.co.uk; Ennaceur, S.M.; Matthews, M.B.; Roussel, P.; Bayer, P.D.

    2016-08-01

    In plutonium-gallium (Pu-Ga) alloys that have a Ga content of 0.3–0.4 wt%, their readiness to transform to α′ renders them of particular interest in efforts to understand the tenuous nature of δ phase stability. The present study is a comprehensive examination of the structure and phase stability of a cast Pu-0.32 wt% Ga alloy, the Ga content being close to the minimum amount needed to retain the δ phase to ambient temperature. The alloy was characterised in both the as-cast condition as well as following a homogenising heat treatment. The 250-h heat treatment at 450 °C was shown to achieve an apparently stable δ-Pu phase. However, the stability of the δ-Pu phase was shown to be marginal: partial transformation to α′-Pu was observed when the alloy was subjected to hydrostatic compression. Similar transformation was also apparent during metallographic preparation as well as during hardness indentation. The results provide new understanding of the nature of δ phase stability. - Highlights: • New insights into the delta phase stability of a Pu-0.32 wt% Ga alloy. • Density and DSC of as-cast alloy both show α-Pu contents of approximately 30%. • The heat-treated alloy has a largely δ-Pu structure at ambient temperature. • Heat-treated alloy susceptible to δ → α transformation during hardness indentation.

  15. Non-equilibrium phase stabilization versus bubble nucleation at a nanoscale-curved Interface

    Science.gov (United States)

    Schiffbauer, Jarrod; Luo, Tengfei

    Using continuum dynamic van der Waals theory in a radial 1D geometry with a Lennard-Jones fluid model, we investigate the nature of vapor bubble nucleation near a heated, nanoscale-curved convex interface. Vapor bubble nucleation and growth are observed for interfaces with sufficiently large radius of curvature while phase stabilization of a superheated fluid layer occurs at interfaces with smaller radius. The hypothesis that the high Laplace pressure required for stable equilibrium of very small bubbles is responsible for phase stability is tested by effectively varying the parameter which controls liquid-vapor surface tension. In doing so, the liquid-vapor surface tension- hence Laplace pressure-is shown to have limited effect on phase stabilization vs. bubble nucleation. However, the strong dependence of nucleation on leading-order momentum transport, i.e. viscous dissipation, near the heated inner surface is demonstrated. We gratefully acknowledge ND Energy for support through the ND Energy Postdoctoral Fellowship program and the Army Research Office, Grant No. W911NF-16-1-0267, managed by Dr. Chakrapani Venanasi.

  16. Experimental and computational study on the phase stability of Al-containing cubic transition metal nitrides

    International Nuclear Information System (INIS)

    Rovere, Florian; Mayrhofer, Paul H; Music, Denis; Ershov, Sergey; Baben, Moritz to; Schneider, Jochen M; Fuss, Hans-Gerd

    2010-01-01

    The phase stability of Al-containing cubic transition metal (TM) nitrides, where Al substitutes for TM (i.e. TM 1-x Al x N), is studied as a function of the TM valence electron concentration (VEC). X-ray diffraction and thermal analyses data of magnetron sputtered Ti 1-x Al x N, V 1-x Al x N and Cr 1-x Al x N films indicate increasing phase stability of cubic TM 1-x Al x N at larger Al contents and higher temperatures with increasing TM VEC. These experimental findings can be understood based on first principle investigations of ternary cubic TM 1-x Al x N with TM = Sc, Ti, V, Cr, Y, Zr and Nb where the TM VEC and the lattice strain are systematically varied. However, our experimental data indicate that, in addition to the decomposition energetics (cubic TM 1-x Al x N → cubic TMN + hexagonal AlN), future stability models have to include nitrogen release as one of the mechanisms that critically determine the overall phase stability of TM 1-x Al x N.

  17. First-principles calculations of the structural and thermodynamic properties of bcc, fcc and hcp solid solutions in the Al-TM (TM = Ti, Zr and Hf) systems: A comparison of cluster expansion and supercell methods

    International Nuclear Information System (INIS)

    Ghosh, G.; Walle, A. van de; Asta, M.

    2008-01-01

    The thermodynamic properties of solid solutions with body-centered cubic (bcc), face-centered cubic (fcc) and hexagonal close-packed (hcp) structures in the Al-TM (TM = Ti, Zr and Hf) systems are calculated from first-principles using cluster expansion (CE), Monte-Carlo simulation and supercell methods. The 32-atom special quasirandom structure (SQS) supercells are employed to compute properties at 25, 50 and 75 at.% TM compositions, and 64-atom supercells have been employed to compute properties of alloys in the dilute concentration limit (one solute and 63 solvent atoms). In general, the energy of mixing (Δ m E) calculated by CE and dilute supercells agree very well. In the concentrated region, the Δ m E values calculated by CE and SQS methods also agree well in many cases; however, noteworthy discrepancies are found in some cases, which we argue originate from inherent elastic and dynamic instabilities of the relevant parent lattice structures. The importance of short-range order on the calculated values of Δ m E for hcp Al-Ti alloys is demonstrated. We also present calculated results for the composition dependence of the atomic volumes in random solid solutions with bcc, fcc and hcp structures. The properties of solid solutions reported here may be integrated within the CALPHAD formalism to develop reliable thermodynamic databases in order to facilitate: (i) calculations of stable and metastable phase diagrams of binary and multicomponent systems, (ii) alloy design, and (iii) processing of Al-TM-based alloys

  18. Extended thermodynamics

    CERN Document Server

    Müller, Ingo

    1993-01-01

    Physicists firmly believe that the differential equations of nature should be hyperbolic so as to exclude action at a distance; yet the equations of irreversible thermodynamics - those of Navier-Stokes and Fourier - are parabolic. This incompatibility between the expectation of physicists and the classical laws of thermodynamics has prompted the formulation of extended thermodynamics. After describing the motifs and early evolution of this new branch of irreversible thermodynamics, the authors apply the theory to mon-atomic gases, mixtures of gases, relativistic gases, and "gases" of phonons and photons. The discussion brings into perspective the various phenomena called second sound, such as heat propagation, propagation of shear stress and concentration, and the second sound in liquid helium. The formal mathematical structure of extended thermodynamics is exposed and the theory is shown to be fully compatible with the kinetic theory of gases. The study closes with the testing of extended thermodynamics thro...

  19. Ethanol as an Alternative Fuel for Automobiles: Using the First Law of Thermodynamics to Calculate the "Corn-Area-per-Car" Ratio

    Science.gov (United States)

    Pietro, William J.

    2009-01-01

    Students will use the first law of thermodynamics to determine the feasibility of using corn ethanol as an alternative to fossil fuels in automobiles. Energy flow is tracked from the Sun, to photosynthesized carbohydrate, to ethanol through fermentation, and finally to work in the combustion engine. Feasibility is gauged by estimating a…

  20. Thermodynamics of Micellar Systems : Comparison of Mass Action and Phase Equilibrium Models for the Calculation of Standard Gibbs Energies of Micelle Formation

    NARCIS (Netherlands)

    Blandamer, Michael J.; Cullis, Paul M.; Soldi, L. Giorgio; Engberts, Jan B.F.N.; Kacperska, Anna; Os, Nico M. van

    1995-01-01

    Micellar colloids are distinguished from other colloids by their association-dissociation equilibrium in solution between monomers, counter-ions and micelles. According to classical thermodynamics, the standard Gibbs energy of formation of micelles at fixed temperature and pressure can be related to

  1. Dehalogenation Potential of Municipal Waste Incineration Fly Ash. II. Comparison of Dehalogenation Pathways of Fly Ash and Model Fly Ash with Thermodynamic Calculations

    Czech Academy of Sciences Publication Activity Database

    Bureš, M.; Pekárek, Vladimír; Karban, Jindřich; Fišerová, Eva

    2003-01-01

    Roč. 10, č. 2 (2003), s. 121-125 ISSN 0944-1344 R&D Projects: GA AV ČR IAA4072901; GA AV ČR IBS4072108 Institutional research plan: CEZ:AV0Z4072921 Keywords : dechlorination * thermodynamics * hexachlorobenzene Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.216, year: 2003

  2. Application of the quasi-Gaussian entropy theory to the calculation of thermodynamic properties of water and methane in the liquid and gas phase

    NARCIS (Netherlands)

    Apol, M.E F; Amadei, A; Berendsen, H.J.C.

    1996-01-01

    In this article we investigate the applicability of the statistical Gamma state as following from the quasi-Gaussian entropy theory, where all thermodynamic properties at every temperature are obtained from the knowledge of the potential energy distribution at one temperature. We compared for a

  3. Experimental and computer thermodynamics evaluations of an Al-Si-Coating on a quenchable steel

    International Nuclear Information System (INIS)

    Trindade, Vicente Braz

    2017-01-01

    High-strength steels are commonly used in the automobile industry in order to reduce the weight of the vehicles. However, a technical difficulty appears due to the need of hot stamping of the components, which leads to oxidation. Therefore, the application of a coating on the substrate to avoid high-temperature oxidation is used. In this work, experimental analysis and computer thermodynamic calculation were used to describe the phase transformations within an Al-Si coating on a quenchable high strength steel. The Al-Si coating was deposited by hot dipping and its characterization was done using SEM and XRD techniques. Computer thermodynamics calculations were done using the commercial software FactSage using the Calphad methodology. It demonstrated a good relationship between the experimental results and the computer calculations of phase stabilities for the as-deposited condition and after diffusion experiment at 920 deg C for 7 minutes, which simulates the thermal cycle of hot stamping of the quenchable steel used. (author)

  4. Experimental and computer thermodynamics evaluations of an Al-Si-Coating on a quenchable steel

    Energy Technology Data Exchange (ETDEWEB)

    Trindade, Vicente Braz, E-mail: vicentebraz@yahoo.com.b [Universidade Federal de Ouro Preto (UFOP), Ouro Preto, MG (Brazil). Escola de Minas. Departamento de Engenharia Metalurgica e de Materiais; Christ, Hans-Juergen, E-mail: christ@ifwt.mb.uni-siegen.de [University of Siegen (Germany)

    2017-01-15

    High-strength steels are commonly used in the automobile industry in order to reduce the weight of the vehicles. However, a technical difficulty appears due to the need of hot stamping of the components, which leads to oxidation. Therefore, the application of a coating on the substrate to avoid high-temperature oxidation is used. In this work, experimental analysis and computer thermodynamic calculation were used to describe the phase transformations within an Al-Si coating on a quenchable high strength steel. The Al-Si coating was deposited by hot dipping and its characterization was done using SEM and XRD techniques. Computer thermodynamics calculations were done using the commercial software FactSage using the Calphad methodology. It demonstrated a good relationship between the experimental results and the computer calculations of phase stabilities for the as-deposited condition and after diffusion experiment at 920 deg C for 7 minutes, which simulates the thermal cycle of hot stamping of the quenchable steel used. (author)

  5. First-Principles Investigation of Phase Stability, Electronic Structure and Optical Properties of MgZnO Monolayer

    Directory of Open Access Journals (Sweden)

    Changlong Tan

    2016-10-01

    Full Text Available MgZnO bulk has attracted much attention as candidates for application in optoelectronic devices in the blue and ultraviolet region. However, there has been no reported study regarding two-dimensional MgZnO monolayer in spite of its unique properties due to quantum confinement effect. Here, using density functional theory calculations, we investigated the phase stability, electronic structure and optical properties of MgxZn1−xO monolayer with Mg concentration x range from 0 to 1. Our calculations show that MgZnO monolayer remains the graphene-like structure with various Mg concentrations. The phase segregation occurring in bulk systems has not been observed in the monolayer due to size effect, which is advantageous for application. Moreover, MgZnO monolayer exhibits interesting tuning of electronic structure and optical properties with Mg concentration. The band gap increases with increasing Mg concentration. More interestingly, a direct to indirect band gap transition is observed for MgZnO monolayer when Mg concentration is higher than 75 at %. We also predict that Mg doping leads to a blue shift of the optical absorption peaks. Our results may provide guidance for designing the growth process and potential application of MgZnO monolayer.

  6. General thermodynamics

    CERN Document Server

    Olander, Donald

    2007-01-01

    The book’s methodology is unified, concise, and multidisciplinary, allowing students to understand how the principles of thermodynamics apply to all technical fields that touch upon this most fundamental of scientific theories. It also offers a rigorous approach to the quantitative aspects of thermodynamics, accompanied by clear explanations to help students transition smoothly from the physical concepts to their mathematical representations

  7. Thermodynamic Properties and Thermodynamic Geometries of Black p-Branes

    International Nuclear Information System (INIS)

    Yi-Huan Wei; Xiao Cui; Jia-Xin Zhao

    2016-01-01

    The heat capacity and the electric capacitance of the black p-branes (BPB) are generally defined, then they are calculated for some special processes. It is found that the Ruppeiner thermodynamic geometry of BPB is flat. Finally, we give some discussions for the flatness of the Ruppeiner thermodynamic geometry of BPB and some black holes. (paper)

  8. 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.

  9. A review of reaction rates and thermodynamic and transport properties for the 11-species air model for chemical and thermal nonequilibrium calculations to 30000 K

    Science.gov (United States)

    Gupta, Roop N.; Yos, Jerrold M.; Thompson, Richard A.

    1989-01-01

    Reaction rate coefficients and thermodynamic and transport properties are provided for the 11-species air model which can be used for analyzing flows in chemical and thermal nonequilibrium. Such flows will likely occur around currently planned and future hypersonic vehicles. Guidelines for determining the state of the surrounding environment are provided. Approximate and more exact formulas are provided for computing the properties of partially ionized air mixtures in such environments.

  10. 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.

  11. Carrier-envelope phase stabilization and control using a transmission grating compressor and an AOPDF.

    Science.gov (United States)

    Canova, Lorenzo; Chen, Xiaowei; Trisorio, Alexandre; Jullien, Aurélie; Assion, Andreas; Tempea, Gabriel; Forget, Nicolas; Oksenhendler, Thomas; Lopez-Martens, Rodrigo

    2009-05-01

    Carrier-envelope phase (CEP) stabilization of a femtosecond chirped-pulse amplification system featuring a compact transmission grating compressor is demonstrated. The system includes two amplification stages and routinely generates phase-stable (approximately 250 mrad rms) 2 mJ, 25 fs pulses at 1 kHz. Minimizing the optical pathway in the compressor enables phase stabilization without feedback control of the grating separation or beam pointing. We also demonstrate for the first time to the best of our knowledge, out-of-loop control of the CEP using an acousto-optic programmable dispersive filter inside the laser chain.

  12. Carrier-envelope phase-stabilized attosecond pulses from asymmetric molecules

    International Nuclear Information System (INIS)

    Lan Pengfei; Lu Peixiang; Cao Wei; Li Yuhua; Wang Xinlin

    2007-01-01

    High-order harmonic generation from asymmetric molecules is investigated, and the concept of phase-stabilized infrared ultrashort laser pulses is extended to the extreme ultraviolet regime. It is shown that the ionization symmetry in consecutive half optical cycles is broken for asymmetric molecules, and both even and odd harmonics with comparable intensity are produced. In the time domain, only one attosecond pulse is generated in each cycle of the driving field, and the carrier-envelope phases of the attosecond pulses are equal. Consequently, a clean attosecond pulse train with the same carrier-envelope phase from pulse to pulse is obtained in the extreme ultraviolet regime

  13. Vecksler-Macmillan phase stability for neutral atoms accelerated by a laser beam

    Science.gov (United States)

    Mel'nikov, I. V.; Haus, J. W.; Kazansky, P. G.

    2003-05-01

    We use a Fokker-Planck equation to study the phenomenon of accelerating a neutral atom bunch by a chirped optical beam. This method enables us to obtain a semi-analytical solution to the problem in which a wide range of parameters can be studied. In addition it provides a simple physical interpretation where the problem is reduced to an analogous problem of charged particles accelerators, that is, the Vecksler-Macmillan principle of phase stability. A possible experimental scenario is suggested, which uses a photonic crystal fiber as the guiding medium.

  14. Improving the phase stability of the SLAC rf driveline network for SLC operation

    International Nuclear Information System (INIS)

    Weaver, J.N.; Hogg, H.A.

    1983-01-01

    Successful operation of the Stanford Linear Collider (SLC) will require greater phase stability from the two-mile long rf drive network than previous linac operation did. This paper discusses four proposed modifications of the present system that should help achieve the general objective to reduce all long term temperature and atmospheric pressure induced phase variations to less than 20 0 at 2856 MHz, so that the phase/amplitude detector subsystems, which will control the network output phases relative to a beam reference, will operate within their most accurate ranges

  15. Experimental and computational study on the effect of yttrium on the phase stability of sputtered Cr-Al-Y-N hard coatings

    International Nuclear Information System (INIS)

    Rovere, F.; Music, D.; Schneider, J.M.; Mayrhofer, P.H.

    2010-01-01

    The effect of Y incorporation into cubic Cr-Al-N (B1) was studied using ab initio calculations, X-ray diffraction and energy-dispersive X-ray analysis of sputtered quaternary nitride films. The data obtained indicate that the Y incorporation shifts the critical Al content, where the hexagonal (B4) structure is stable, to lower values. The calculated critical Al contents of x ∼ 0.75 for Cr 1-x Al x N and x ∼ 0.625 for Cr 1-x-y Al x Y y N with y = 0.125 are consistent with experimentally obtained values of x = 0.69 for Cr 1-x Al x N and x = 0.68 and 0.61 for Cr 1-x-y Al x Y y N with y = 0.02 and 0.06, respectively. This may be understood based on the electronic structure. Both Cr and Al can randomly be substituted by Y. The substitution of Cr by Y increases the phase stability due to depletion of non-bonding (anti-bonding) states, while the substitution of Al by Y decreases the phase stability mainly due to lattice strain.

  16. Influence of Si and N additions on structure and phase stability of Ge(2)Sb(2)Te(5) thin films.

    Science.gov (United States)

    Kölpin, Helmut; Music, Denis; Laptyeva, Galyna; Ghadimi, Reza; Merget, Florian; Richter, Silvia; Mykhaylonka, Ruslàn; Mayer, Joachim; Schneider, Jochen M

    2009-10-28

    The influence of Si and N in Ge(2)Sb(2)Te(5) (space group [Formula: see text]) on structure and phase stability thereof was studied experimentally by thin film growth and characterization as well as theoretically by ab initio calculations. It was found that Si and N most probably accumulate in the amorphous matrix embedding Ge(2)Sb(2)Te(5) grains. The incorporation of Si and N in these samples causes an increase of the crystallization temperature and the formation of finer grains. N is more efficient in increasing the crystallization temperature and in reducing the grain size than Si which can be understood based on the bonding analysis. The incorporation of both Si and N in Ge(2)Sb(2)Te(5) is energetically unfavourable, leading to finer grains and larger crystallization temperatures. While in the case of Si additions no significant changes in bonding are observed, N additions appear to enable the formation of strong Te-N bonds in the amorphous matrix, which are shown to be almost twice as strong as the strongest bonds in unalloyed Ge(2)Sb(2)Te(5).

  17. Influence of Si and N additions on structure and phase stability of Ge2Sb2Te5 thin films

    International Nuclear Information System (INIS)

    Koelpin, Helmut; Music, Denis; Mykhaylonka, Ruslan; Schneider, Jochen M; Laptyeva, Galyna; Ghadimi, Reza; Richter, Silvia; Mayer, Joachim; Merget, Florian

    2009-01-01

    The influence of Si and N in Ge 2 Sb 2 Te 5 (space group Fm3-barm) on structure and phase stability thereof was studied experimentally by thin film growth and characterization as well as theoretically by ab initio calculations. It was found that Si and N most probably accumulate in the amorphous matrix embedding Ge 2 Sb 2 Te 5 grains. The incorporation of Si and N in these samples causes an increase of the crystallization temperature and the formation of finer grains. N is more efficient in increasing the crystallization temperature and in reducing the grain size than Si which can be understood based on the bonding analysis. The incorporation of both Si and N in Ge 2 Sb 2 Te 5 is energetically unfavourable, leading to finer grains and larger crystallization temperatures. While in the case of Si additions no significant changes in bonding are observed, N additions appear to enable the formation of strong Te-N bonds in the amorphous matrix, which are shown to be almost twice as strong as the strongest bonds in unalloyed Ge 2 Sb 2 Te 5 .

  18. Composition-dependent properties and phase stability of Fe-Pd ferromagnetic shape memory alloys: A first-principles study

    Science.gov (United States)

    Li, Chun-Mei; Hu, Yan-Fei

    2017-12-01

    The composition-dependent properties and their correlation with the phase stability of Fe75+xPd25-x (- 10.0 ≤x ≤10.0 ) alloys are systematically investigated by using first-principles exact muffin-tin orbitals (EMTO)-coherent potential approximation (CPA) calculations. It is shown that the martensitic transformation (MT) from L 12 to body-centered-tetragonal (bct) occurs in the ordered alloys with about -5.0 ≤x ≤10.0 . In both the L 12 and bct phases, the evaluated a and c/a agree well with the available experimental data; the average magnetic moment per atom increases whereas the local magnetic moments of Fe atoms, dependent on both their positions and the structure of the alloy, decrease with increasing x. The tetragonal shear elastic constant of the L 12 phase ( C ' ) decreases whereas that of the bct phase (Cs) increases with x. The tetragonality of the martensite ( |1 -c /a | ) increases whereas its energy relative to the austenite with a negative value decreases with Fe addition. All these effects account for the increase of MT temperature (TM) with x. The MT from L 12 to bct is finally confirmed originating from the splitting of Fe 3d Eg and T2 g bands upon tetragonal distortion due to the Jahn-Teller effect.

  19. Atmospheric thermodynamics

    CERN Document Server

    Iribarne, J V

    1973-01-01

    The thermodynamics of the atmosphere is the subject of several chapters in most textbooks on dynamic meteorology, but there is no work in English to give the subject a specific and more extensive treatment. In writing the present textbook, we have tried to fill this rather remarkable gap in the literature related to atmospheric sciences. Our aim has been to provide students of meteorology with a book that can playa role similar to the textbooks on chemical thermodynamics for the chemists. This implies a previous knowledge of general thermodynamics, such as students acquire in general physics courses; therefore, although the basic principles are reviewed (in the first four chapters), they are only briefly discussed, and emphasis is laid on those topics that will be useful in later chapters, through their application to atmospheric problems. No attempt has been made to introduce the thermodynamics of irreversible processes; on the other hand, consideration of heterogeneous and open homogeneous systems permits a...

  20. Thermodynamic holography

    Science.gov (United States)

    Wei, Bo-Bo; Jiang, Zhan-Feng; Liu, Ren-Bao

    2015-01-01

    The holographic principle states that the information about a volume of a system is encoded on the boundary surface of the volume. Holography appears in many branches of physics, such as optics, electromagnetism, many-body physics, quantum gravity, and string theory. Here we show that holography is also an underlying principle in thermodynamics, a most important foundation of physics. The thermodynamics of a system is fully determined by its partition function. We prove that the partition function of a finite but arbitrarily large system is an analytic function on the complex plane of physical parameters, and therefore the partition function in a region on the complex plane is uniquely determined by its values along the boundary. The thermodynamic holography has applications in studying thermodynamics of nano-scale systems (such as molecule engines, nano-generators and macromolecules) and provides a new approach to many-body physics. PMID:26478214

  1. Phase stability analysis of liquid-liquid equilibrium with stochastic methods

    Directory of Open Access Journals (Sweden)

    G. Nagatani

    2008-09-01

    Full Text Available Minimization of Gibbs free energy using activity coefficient models and nonlinear equation solution techniques is commonly applied to phase stability problems. However, when conventional techniques, such as the Newton-Raphson method, are employed, serious convergence problems may arise. Due to the existence of multiple solutions, several problems can be found in modeling liquid-liquid equilibrium of multicomponent systems, which are highly dependent on the initial guess. In this work phase stability analysis of liquid-liquid equilibrium is investigated using the NRTL model. For this purpose, two distinct stochastic numerical algorithms are employed to minimize the tangent plane distance of Gibbs free energy: a subdivision algorithm that can find all roots of nonlinear equations for liquid-liquid stability analysis and the Simulated Annealing method. Results obtained in this work for the two stochastic algorithms are compared with those of the Interval Newton method from the literature. Several different binary and multicomponent systems from the literature were successfully investigated.

  2. Thermodynamic analysis of PBMR plant

    International Nuclear Information System (INIS)

    Sen, S.; Kadiroglu, O.K.

    2002-01-01

    The thermodynamic analysis of a PBMR is presented for various pressures and temperatures values. The design parameters of the components of the power plant are calculated and an optimum cycle for the maximum thermal efficiency is sought for. (author)

  3. 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

  4. Thermodynamic properties and solidification kinetics of intermetallic Ni{sub 7}Zr{sub 2} alloy investigated by electrostatic levitation technique and theoretical calculations

    Energy Technology Data Exchange (ETDEWEB)

    Li, L. H.; Hu, L.; Yang, S. J.; Wang, W. L.; Wei, B., E-mail: bbwei@nwpu.edu.cn [Department of Applied Physics, Northwestern Polytechnical University, Xi' an 710072 (China)

    2016-01-21

    The thermodynamic properties, including the density, volume expansion coefficient, ratio of specific heat to emissivity of intermetallic Ni{sub 7}Zr{sub 2} alloy, have been measured using the non-contact electrostatic levitation technique. These properties vary linearly with temperature at solid and liquid states, even down to the obtained maximum undercooling of 317 K. The enthalpy, glass transition, diffusion coefficient, shear viscosity, and surface tension were obtained by using molecular dynamics simulations. Ni{sub 7}Zr{sub 2} has a relatively poor glass forming ability, and the glass transition temperature is determined as 1026 K. The inter-diffusivity of Ni{sub 7}Zr{sub 2} alloy fitted by Vogel–Fulcher–Tammann law yields a fragility parameter of 8.49, which indicates the fragile nature of this alloy. Due to the competition of increased thermodynamic driving force and decreased atomic diffusion, the dendrite growth velocity of Ni{sub 7}Zr{sub 2} compound exhibits double-exponential relationship to the undercooling. The maximum growth velocity is predicted to be 0.45 m s{sup −1} at the undercooling of 335 K. Theoretical analysis reveals that the dendrite growth is a diffusion-controlled process and the atomic diffusion speed is only 2.0 m s{sup −1}.

  5. Influence of the Al distribution on the structure, elastic properties, and phase stability of supersaturated Ti1-xAlxN

    International Nuclear Information System (INIS)

    Mayrhofer, P. H.; Music, D.; Schneider, J. M.

    2006-01-01

    Ti 1-x Al x N films and/or their alloys are employed in many industrial applications due to their excellent mechanical and thermal properties. Synthesized by plasma-assisted vapor deposition, Ti 1-x Al x N is reported to crystallize in the cubic NaCl (c) structure for AlN mole fractions below 0.4-0.91, whereas at larger Al contents the hexagonal ZnS-wurtzite (w) structure is observed. Here we use ab initio calculations to analyze the effect of composition and Al distribution on the metal sublattice on phase stability, structure, and elastic properties of c-Ti 1-x Al x N and w-Ti 1-x Al x N. We show that the phase stability of supersaturated c-Ti 1-x Al x N not only depends on the chemical composition but also on the Al distribution of the metal sublattice. An increase of the metastable solubility limit of AlN in c-Ti 1-x Al x N from 0.64 to 0.74 is obtained by decreasing the number of Ti-Al bonds. This can be understood by considering the Al distribution induced changes of the electronic structure, bond energy, and configurational entropy. This may in part explain the large variation of the metastable solubility limit reported in the literature

  6. The OpenCalphad thermodynamic software interface

    Science.gov (United States)

    Sundman, Bo; Kattner, Ursula R; Sigli, Christophe; Stratmann, Matthias; Le Tellier, Romain; Palumbo, Mauro; Fries, Suzana G

    2017-01-01

    Thermodynamic data are needed for all kinds of simulations of materials processes. Thermodynamics determines the set of stable phases and also provides chemical potentials, compositions and driving forces for nucleation of new phases and phase transformations. Software to simulate materials properties needs accurate and consistent thermodynamic data to predict metastable states that occur during phase transformations. Due to long calculation times thermodynamic data are frequently pre-calculated into “lookup tables” to speed up calculations. This creates additional uncertainties as data must be interpolated or extrapolated and conditions may differ from those assumed for creating the lookup table. Speed and accuracy requires that thermodynamic software is fully parallelized and the Open-Calphad (OC) software is the first thermodynamic software supporting this feature. This paper gives a brief introduction to computational thermodynamics and introduces the basic features of the OC software and presents four different application examples to demonstrate its versatility. PMID:28260838

  7. Thermodynamic and lattice parameter calculation of TiC x produced from Al-Ti-C powders by laser igniting self-propagating high-temperature synthesis

    International Nuclear Information System (INIS)

    Li, Y.X.; Hu, J.D.; Wang, H.Y.; Guo, Z.X.; Chumakov, A.N.

    2007-01-01

    TiC x has been formed by self-propagating high-temperature synthesis (SHS) from elemental powder mixtures with a range of C/Ti ratios. The combusting behavior of the powder mixtures was investigated. The effect of the processing variables on the lattice parameter and the composition of TiC were examined. The results show that lattice parameters of TiC x increase with the increase of C/Ti ratio. The variation of Gibbs free energy in Al-Ti-C system was studied based on the thermodynamics theory. The results show that TiC and Al 3 Ti phases are easier to form than Al 4 C 3 phase

  8. A review of reaction rates and thermodynamic and transport properties for an 11-species air model for chemical and thermal nonequilibrium calculations to 30000 K

    Science.gov (United States)

    Gupta, Roop N.; Yos, Jerrold M.; Thompson, Richard A.; Lee, Kam-Pui

    1990-01-01

    Reaction rate coefficients and thermodynamic and transport properties are reviewed and supplemented for the 11-species air model which can be used for analyzing flows in chemical and thermal nonequilibrium up to temperatures of 3000 K. Such flows will likely occur around currently planned and future hypersonic vehicles. Guidelines for determining the state of the surrounding environment are provided. Curve fits are given for the various species properties for their efficient computation in flowfield codes. Approximate and more exact formulas are provided for computing the properties of partially ionized air mixtures in a high energy environment. Limitations of the approximate mixing laws are discussed for a mixture of ionized species. An electron number-density correction for the transport properties of the charged species is obtained. This correction has been generally ignored in the literature.

  9. Stochastic thermodynamics

    Science.gov (United States)

    Eichhorn, Ralf; Aurell, Erik

    2014-04-01

    'Stochastic thermodynamics as a conceptual framework combines the stochastic energetics approach introduced a decade ago by Sekimoto [1] with the idea that entropy can consistently be assigned to a single fluctuating trajectory [2]'. This quote, taken from Udo Seifert's [3] 2008 review, nicely summarizes the basic ideas behind stochastic thermodynamics: for small systems, driven by external forces and in contact with a heat bath at a well-defined temperature, stochastic energetics [4] defines the exchanged work and heat along a single fluctuating trajectory and connects them to changes in the internal (system) energy by an energy balance analogous to the first law of thermodynamics. Additionally, providing a consistent definition of trajectory-wise entropy production gives rise to second-law-like relations and forms the basis for a 'stochastic thermodynamics' along individual fluctuating trajectories. In order to construct meaningful concepts of work, heat and entropy production for single trajectories, their definitions are based on the stochastic equations of motion modeling the physical system of interest. Because of this, they are valid even for systems that are prevented from equilibrating with the thermal environment by external driving forces (or other sources of non-equilibrium). In that way, the central notions of equilibrium thermodynamics, such as heat, work and entropy, are consistently extended to the non-equilibrium realm. In the (non-equilibrium) ensemble, the trajectory-wise quantities acquire distributions. General statements derived within stochastic thermodynamics typically refer to properties of these distributions, and are valid in the non-equilibrium regime even beyond the linear response. The extension of statistical mechanics and of exact thermodynamic statements to the non-equilibrium realm has been discussed from the early days of statistical mechanics more than 100 years ago. This debate culminated in the development of linear response

  10. Thermodynamic approach to biomass gasification

    International Nuclear Information System (INIS)

    Boissonnet, G.; Seiler, J.M.

    2003-01-01

    The document presents an approach of biomass transformation in presence of steam, hydrogen or oxygen. Calculation results based on thermodynamic equilibrium are discussed. The objective of gasification techniques is to increase the gas content in CO and H 2 . The maximum content in these gases is obtained when thermodynamic equilibrium is approached. Any optimisation action of a process. will, thus, tend to approach thermodynamic equilibrium conditions. On the other hand, such calculations can be used to determine the conditions which lead to an increase in the production of CO and H 2 . An objective is also to determine transformation enthalpies that are an important input for process calculations. Various existing processes are assessed, and associated thermodynamic limitations are evidenced. (author)

  11. 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...

  12. An S-band high gain relativistic klystron amplifier with high phase stability

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Y. [Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900 (China); Science and Technology on High Power Microwave Laboratory, Mianyang 621900 (China); Li, Z. H.; Xu, Z.; Ma, Q. S. [Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900 (China); Xie, H. Q. [College of Science, Southwestern University of Science and Technology, Mianyang 621010 (China)

    2014-11-15

    For the purpose of coherent high power microwave combining, an S-band high gain relativistic klystron amplifier with high phase stability is presented and studied. By the aid of 3D particle-in-cell code and circuit simulation software, the mechanism of parasitic oscillation in the device is investigated. And the RF lossy material is adopted in the simulation and experiment to suppress the oscillation. The experimental results show that with an input RF power of 10 kW, a microwave pulse with power of 1.8 GW is generated with a gain of 52.6 dB. And the relative phase difference fluctuation between output microwave and input RF signal is less than ±10° in 90 ns.

  13. Phase stability of TiH{sub 2} under high pressure and temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Selva Vennila, R.; Durygin, A.; Saxena, S.K. [Center for Study of Matter at Extreme Conditions (CeSMEC), Florida International University, VH-150, University Park, Miami, FL 33199 (United States); Merlini, Marco [European Synchrotron Radiation Facility (ESRF), Grenoble 38043 (France); Wang, Zhongwu [Cornell High Energy Synchrotron Source (CHESS), Wilson Laboratory, Cornell University, Ithaca, NY 14853 (United States)

    2008-11-15

    Phase stability of titanium hydride (TiH{sub 2}) was studied at high pressure-high temperature conditions using synchrotron radiation under non-hydrostatic conditions. Resistive heating method was used to heat the sample to a maximum temperature of 873 K in a diamond anvil cell (DAC) under pressure up to 12 GPa. Pressure-temperature behavior was studied by varying the temperature upto 823 K in steps of 50 K with pressure variations within 3 GPa. Structural phase transformation from tetragonal (I4/mmm) to cubic (Fm-3 m) was observed with increase in temperature. Tetragonal phase was found to be stabilized when the sample was subjected to pressure and temperature cycle. (author)

  14. Precipitation Effect on Mechanical Properties and Phase Stability of High Manganese Steel

    Science.gov (United States)

    Bae, Cheoljun; Kim, Rosa; Lee, Un-Hae; Kim, Jongryoul

    2017-09-01

    High manganese (Mn) steels are attractive for automotive applications due to their excellent tensile strength and superior elongation. However, the relatively low yield strength of Mn steels compared to other advanced high-strength steels is a critical problem limiting their use in structural parts. In order to increase the yield strength, the precipitation hardening effect of Mn steels was investigated by the addition of carbide-forming elements. Changes in the austenite phase stability were also evaluated in terms of stacking fault energy (SFE). As a result, fine V(C,N) precipitates were found to increase the yield strength effectively but to lower the SFE by the consumption of matrix carbons. For achieving precipitation hardening without sacrificing austenite stability, the soluble carbon content was discussed.

  15. Phase stability in wear-induced supersaturated Al-Ti solid solution

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Y.; Yokoyama, K. [Dept. of Functional Machinery Mechanics Shinshu Univ., Ueda (Japan); Hosoda, H. [Precision and Intelligence Lab., Tokyo Inst. of Tech., Nagatsuta, Midori-ku, Yokohama (Japan)

    2002-07-01

    Al-Ti supersaturated solid solutions were introduced by wear testing and the rapid quenching of an Al/Al{sub 3}Ti composite (part of an Al/Al{sub 3}Ti functionally graded material) that was fabricated using the centrifugal method. The phase stability of the supersaturated solid solution was studied through systematic annealing of the supersaturated solid solution. It was found that the Al-Ti supersaturated solid solution decomposed into Al and Al{sub 3}Ti intermetallic compound phases during the heat treatment. The Al-Ti supersaturated solid solutions fabricated were, therefore, not an equilibrium phase, and thus decomposed into the equilibrium phases during heat treatment. It was also found that heat treatment leads to a significant hardness increase for the Al-Ti supersaturated solid solution. Finally, it was concluded that formation of the wear-induced supersaturated solid solution layer was a result of severe plastic deformation. (orig.)

  16. Aging and Phase Stability Studies of Alloy 22 FY08 Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Torres, S G

    2008-04-03

    This report is a compilation of work done over the past ten years in support of phase stability studies of Alloy 22 for the Yucca Mountain Project and contains information previously published, reported, and referenced. Most sections are paraphrased here for the convenience of readers. Evaluation of the fabrication processes involved in the manufacture of waste containers is important as these processes can have an effect on the metallurgical structure of an alloy. Because material properties such as strength, toughness, aging kinetics and corrosion resistance are all dependent on the microstructure, it is important that prototypes be built and evaluated for processing effects on the performance of the material. Of particular importance are welds, which have an as-cast microstructure with chemical segregation and precipitation of complex phases resulting from the welding process. The work summarized in this report contains information on the effects of fabrication processes such as solution annealing, stress mitigation, heat-to-heat variability, and welding on the kinetics of precipitation, mechanical, and corrosion properties. For a waste package lifetime of thousands of years, it is impossible to test directly in the laboratory the behavior of Alloy 22 under expected repository conditions. The changes that may occur in these materials must be accelerated. For phase stability studies, this is achieved by accelerating the phase transformations by increasing test temperatures above those anticipated in the proposed repository. For these reasons, Alloy 22 characterization specimens were aged at Lawrence Livermore National Laboratory (LLNL) Aging Facilities for times from 1 hour up to 8 years at temperatures ranging from 200-750 C. These data as well as the data from specimens aged at 260 C, 343 C, and 427 C for 100,028 hours at Haynes International will be used for performance confirmation and model validation.

  17. New and extended parameterization of the thermodynamic model AIOMFAC: calculation of activity coefficients for organic-inorganic mixtures containing carboxyl, hydroxyl, carbonyl, ether, ester, alkenyl, alkyl, and aromatic functional groups

    Directory of Open Access Journals (Sweden)

    A. Zuend

    2011-09-01

    algorithms. A number of exemplary calculations for systems containing atmospherically relevant aerosol components are shown. Amongst others, we discuss aqueous mixtures of ammonium sulfate with dicarboxylic acids and with levoglucosan. Overall, the new parameterization of AIOMFAC agrees well with a large number of experimental datasets. However, due to various reasons, for certain mixtures important deviations can occur. The new parameterization makes AIOMFAC a versatile thermodynamic tool. It enables the calculation of activity coefficients of thousands of different organic compounds in organic-inorganic mixtures of numerous components. Models based on AIOMFAC can be used to compute deliquescence relative humidities, liquid-liquid phase separations, and gas-particle partitioning of multicomponent mixtures of relevance for atmospheric chemistry or in other scientific fields.

  18. Thermodynamic Database for the Terrestrial and Planetary Mantle Studies: Where we stand, and some future directions involving experimental studies, numerical protocol for EoS and atomistic calculations (Invited)

    Science.gov (United States)

    Ganguly, J.; Tirone, M.; Sorcar, N.

    2013-12-01

    problem of appropriate combination of binary mixing properties in a multicomponent system, and present simplified a-x formalisms for complex multi-site solutions the full-blown treatment of which requires a body of experimental data that are unlikely to be available in the near future. It appears that Cp and the coefficients of thermal expansion and compression of solids could be calculated quite well form density functional theory (DFT) (e.g. 7), so that the future development of databases should not only consider the available DFT data, but also have active involvement in such studies 'to fill the gap' when reliable data are not available. While the current trend in geodynamic modeling is to use thermodynamic properties in tabulated form, more realistic simulations, which we would try to illustrate by examples, would require real-time thermodynamic calculations for evolving bulk compositions; hence the development of a robust yet simple thermodynamic formulation becomes essential. 1. Fabrichnaya et al. (2004), Springer-verlag; 2. Stixrude and Lithgow-Bertelloni, Geophys. J. Int. (2011) 184, 1180-1213. 3. Holland et al. ( 2013) J. Petrol. 4. Report, Geomaterials Genome Project, March 19-23, 2013, Miami, Florida, NSF Geoinformatics program. 5. Ferreira et al. (1988) Phys Rev B, 37, 10547-10570; 6. Ganguly et al. (1993) Amer Min 78, 583-593 7. Ottonello et a. (2009) PCM 36, 87-106

  19. 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

  20. Accurate calculation of mutational effects on the thermodynamics of inhibitor binding to p38α MAP kinase: a combined computational and experimental study.

    Science.gov (United States)

    Zhu, Shun; Travis, Sue M; Elcock, Adrian H

    2013-07-09

    A major current challenge for drug design efforts focused on protein kinases is the development of drug resistance caused by spontaneous mutations in the kinase catalytic domain. The ubiquity of this problem means that it would be advantageous to develop fast, effective computational methods that could be used to determine the effects of potential resistance-causing mutations before they arise in a clinical setting. With this long-term goal in mind, we have conducted a combined experimental and computational study of the thermodynamic effects of active-site mutations on a well-characterized and high-affinity interaction between a protein kinase and a small-molecule inhibitor. Specifically, we developed a fluorescence-based assay to measure the binding free energy of the small-molecule inhibitor, SB203580, to the p38α MAP kinase and used it measure the inhibitor's affinity for five different kinase mutants involving two residues (Val38 and Ala51) that contact the inhibitor in the crystal structure of the inhibitor-kinase complex. We then conducted long, explicit-solvent thermodynamic integration (TI) simulations in an attempt to reproduce the experimental relative binding affinities of the inhibitor for the five mutants; in total, a combined simulation time of 18.5 μs was obtained. Two widely used force fields - OPLS-AA/L and Amber ff99SB-ILDN - were tested in the TI simulations. Both force fields produced excellent agreement with experiment for three of the five mutants; simulations performed with the OPLS-AA/L force field, however, produced qualitatively incorrect results for the constructs that contained an A51V mutation. Interestingly, the discrepancies with the OPLS-AA/L force field could be rectified by the imposition of position restraints on the atoms of the protein backbone and the inhibitor without destroying the agreement for other mutations; the ability to reproduce experiment depended, however, upon the strength of the restraints' force constant

  1. Thermodynamic properties of cryogenic fluids

    CERN Document Server

    Leachman, Jacob; Lemmon, Eric; Penoncello, Steven

    2017-01-01

    This update to a classic reference text provides practising engineers and scientists with accurate thermophysical property data for cryogenic fluids. The equations for fifteen important cryogenic fluids are presented in a basic format, accompanied by pressure-enthalpy and temperature-entropy charts and tables of thermodynamic properties. It begins with a chapter introducing the thermodynamic relations and functional forms for equations of state, and goes on to describe the requirements for thermodynamic property formulations, needed for the complete definition of the thermodynamic properties of a fluid. The core of the book comprises extensive data tables and charts for the most commonly-encountered cryogenic fluids. This new edition sees significant updates to the data presented for air, argon, carbon monoxide, deuterium, ethane, helium, hydrogen, krypton, nitrogen and xenon. The book supports and complements NIST’s REFPROP - an interactive database and tool for the calculation of thermodynamic propertie...

  2. Statistical thermodynamics

    CERN Document Server

    Schrödinger, Erwin

    1952-01-01

    Nobel Laureate's brilliant attempt to develop a simple, unified standard method of dealing with all cases of statistical thermodynamics - classical, quantum, Bose-Einstein, Fermi-Dirac, and more.The work also includes discussions of Nernst theorem, Planck's oscillator, fluctuations, the n-particle problem, problem of radiation, much more.

  3. Thermodynamic and transport properties of gaseous tetrafluoromethane in chemical equilibrium

    Science.gov (United States)

    Hunt, J. L.; Boney, L. R.

    1973-01-01

    Equations and in computer code are presented for the thermodynamic and transport properties of gaseous, undissociated tetrafluoromethane (CF4) in chemical equilibrium. The computer code calculates the thermodynamic and transport properties of CF4 when given any two of five thermodynamic variables (entropy, temperature, volume, pressure, and enthalpy). Equilibrium thermodynamic and transport property data are tabulated and pressure-enthalpy diagrams are presented.

  4. CRYSTAL CHEMISTRY OF THREE-COMPONENT WHITE DWARFS AND NEUTRON STAR CRUSTS: PHASE STABILITY, PHASE STRATIFICATION, AND PHYSICAL PROPERTIES

    Energy Technology Data Exchange (ETDEWEB)

    Engstrom, T. A.; Yoder, N. C.; Crespi, V. H., E-mail: tae146@psu.edu, E-mail: ncy5007@psu.edu, E-mail: vhc2@psu.edu [Department of Physics, The Pennsylvania State University, University Park, PA 16802 (United States)

    2016-02-20

    A systematic search for multicomponent crystal structures is carried out for five different ternary systems of nuclei in a polarizable background of electrons, representative of accreted neutron star crusts and some white dwarfs. Candidate structures are “bred” by a genetic algorithm and optimized at constant pressure under the assumption of linear response (Thomas–Fermi) charge screening. Subsequent phase equilibria calculations reveal eight distinct crystal structures in the T = 0 bulk phase diagrams, five of which are complicated multinary structures not previously predicted in the context of compact object astrophysics. Frequent instances of geometrically similar but compositionally distinct phases give insight into structural preferences of systems with pairwise Yukawa interactions, including and extending to the regime of low-density colloidal suspensions made in a laboratory. As an application of these main results, we self-consistently couple the phase stability problem to the equations for a self-gravitating, hydrostatically stable white dwarf, with fixed overall composition. To our knowledge, this is the first attempt to incorporate complex multinary phases into the equilibrium phase-layering diagram and mass–radius-composition dependence, both of which are reported for He–C–O and C–O–Ne white dwarfs. Finite thickness interfacial phases (“interphases”) show up at the boundaries between single-component body-centered cubic (bcc) crystalline regions, some of which have lower lattice symmetry than cubic. A second application—quasi-static settling of heavy nuclei in white dwarfs—builds on our equilibrium phase-layering method. Tests of this nonequilibrium method reveal extra phases that play the role of transient host phases for the settling species.

  5. Thermodynamics of chaos

    International Nuclear Information System (INIS)

    Bonasera, A.; Latora, V.; Ploszajczak, M.

    1996-07-01

    The maximal Lyapunov exponents (LE) are calculated, starting from concepts of hydrodynamics. Analytical expressions for the LE can be found in ergodic limit by using results of the classical thermodynamics for a Boltzmann gas and for systems undergoing a second order phase transition. A recipe is given to measure LE in systems which might have a critical behavior, such as a Bose-Einstein condensation or a transition to a quark-gluon plasma. (author)

  6. Thermodynamics Calculation and Experimental Study on Separation of Bismuth from a Bismuth Glance Concentrate Through a Low-Temperature Molten Salt Smelting Process

    Science.gov (United States)

    Yang, Jian-Guang; He, De-Wen; Tang, Chao-Bo; Chen, Yong-Ming; Sun, Ya-Hui; Tang, Mo-Tang

    2011-08-01

    The main purpose of this study is to characterize and separate bismuth from a bismuth glance concentrate through a low-temperature, sulfur-fixing smelting process. This article reports on a study conducted on the optimization of process parameters, such as Na2CO3 and zinc oxide wt pct in charging, smelting temperature, smelting duration on the bismuth yield, resultant crude bismuth grade, and sulfur-fixing rate. A maximum bismuth recovery of 97.31 pct, crude bismuth grade of 96.93 pct, and 98.23 pct sulfur-fixing rate are obtained when a charge (containing 63.50 wt pct of Na2CO3 and 22.50 wt pct of bismuth glance, as well as 5 pct in excess of the stoichiometric requirement of zinc oxide dosage) is smelted at 1000 K (727 °C) for 150 minutes. This smelting operation is free from atmospheric pollution because zinc oxide is used as the sulfur-fixing agent, which can capture sulfur from bismuth sulfide and form the more thermodynamic-stable compound, zinc sulfide. The solid residue is subjected to a mineral dressing operation to obtain suspension, which is filtered to produce a cake, representing the solid particles of zinc sulfide. Based on the results of the chemical content analysis of the as-resultant zinc sulfide, more than 93 pct zinc sulfide can be recovered, and the recovered zinc sulfide grade can reach 60.20 pct. This material can be sold as zinc sulfide concentrate or roasted to be regenerated as zinc oxide.

  7. Phase stability and processing of strontium and magnesium doped lanthanum gallate

    Science.gov (United States)

    Zheng, Feng

    Fuel Cells are one of the most promising energy transformers with respect to ecological and environmental issues. Solid Oxide Fuel Cells (SOFC) are all solid-state devices. One of the challenges to improve a SOFC is to lower the operating temperature while maintaining or increasing its output voltage. Undoped LaGaO3 is an insulator, doping transforms it into an oxygen-ionic conductor. Sr and Mg doped LaGaO3 (LSGM) perovskite is a new oxygen-ionic conductor with higher conductivity than yttria-stabilized zirconia (YSZ). This material is a candidate for a wide variety of electrochemical devices. In order to realize this potential, the phase stability and processing of this material needs to be investigated in detail. In this study, a systematic investigation of the LSGM materials in terms of phase stability, phase transition, sintering, microstructure and electrical conductivity as functions of temperature, doping content and A/B cation ratio has been carried out. The generalized formula of the materials investigated is (La1--xSrx)A(Ga1--yMg y)BO3--delta. Optimized processing parameters have been obtained by investigating their impact on density change and microstructure. Consequently, a suitable compositional window of the LSGM perovskite has been identified for SOFC electrolyte applications. Based on detailed diffraction analysis, it is found that the undoped LaGaO3 takes on the orthorhombic (Pbnm) symmetry at room temperature. This structure changes to rhombohedral (R3c) at 147 +/- 2°C or changes to monoclinic (I2/a) when the doping level increases from 0.1 to 0.2 moles. We have optimized the compositional window to make the single perovskite phase with high oxygen ionic conductivity (x = 0.10 to 0.20 with A/B ratio between 0.98 to 1.02). The best processing condition, starting from glycine nitrate process (GNP) combustion synthesized ultra-fine LSGM powder, is sintering in air at 1500°C for 2 hours. The doped material has higher oxygen ionic conductivity than

  8. Chemical thermodynamics. An introduction

    Energy Technology Data Exchange (ETDEWEB)

    Keszei, Ernoe [Budapest Univ. (Hungary). Dept. of Physical Chemistry

    2012-07-01

    Eminently suitable as a required textbook comprising complete material for or an undergraduate chemistry major course in chemical thermodynamics. Clearly explains details of formal derivations that students can easily follow and so master applied mathematical operations. Offers problems and solutions at the end of each chapter for self-test and self- or group study. This course-derived undergraduate textbook provides a concise explanation of the key concepts and calculations of chemical thermodynamics. Instead of the usual 'classical' introduction, this text adopts a straightforward postulatory approach that introduces thermodynamic potentials such as entropy and energy more directly and transparently. Structured around several features to assist students' understanding, Chemical Thermodynamics: - Develops applications and methods for the ready treatment of equilibria on a sound quantitative basis. - Requires minimal background in calculus to understand the text and presents formal derivations to the student in a detailed but understandable way. - Offers end-of-chapter problems (and answers) for self-testing and review and reinforcement, of use for self- or group study. This book is suitable as essential reading for courses in a bachelor and master chemistry program and is also valuable as a reference or textbook for students of physics, biochemistry and materials science.

  9. Solvation thermodynamics

    CERN Document Server

    Ben-Naim, Arieh

    1987-01-01

    This book deals with a subject that has been studied since the beginning of physical chemistry. Despite the thousands of articles and scores of books devoted to solvation thermodynamics, I feel that some fundamen­ tal and well-established concepts underlying the traditional approach to this subject are not satisfactory and need revision. The main reason for this need is that solvation thermodynamics has traditionally been treated in the context of classical (macroscopic) ther­ modynamics alone. However, solvation is inherently a molecular pro­ cess, dependent upon local rather than macroscopic properties of the system. Therefore, the starting point should be based on statistical mechanical methods. For many years it has been believed that certain thermodynamic quantities, such as the standard free energy (or enthalpy or entropy) of solution, may be used as measures of the corresponding functions of solvation of a given solute in a given solvent. I first challenged this notion in a paper published in 1978 b...

  10. Phase stability, mechanical properties, hardness, and possible reactive routing of chromium triboride from first-principle investigations

    International Nuclear Information System (INIS)

    Zhong, Ming-Min; Kuang, Xiao-Yu; Wang, Zhen-Hua; Shao, Peng; Ding, Li-Ping; Huang, Xiao-Fen

    2013-01-01

    The first-principles calculations are employed to provide a fundamental understanding of the structural features and relative stability, mechanical and electronic properties, and possible reactive route for chromium triboride. The predicted new phase of CrB 3 belongs to the rhombohedral phase with R-3m symmetry and it transforms into a hexagonal phase with P-6m2 symmetry at 64 GPa. The mechanical and thermodynamic stabilities of CrB 3 are verified by the calculated elastic constants and formation enthalpies. Also, the full phonon dispersion calculations confirm the dynamic stability of predicted CrB 3 . Considering the role of metallic contributions, the calculated hardness values from our semiempirical method for rhombohedral and hexagonal phases are 23.8 GPa and 22.1 GPa, respectively. In addition, the large shear moduli, Young's moduli, low Poisson's ratios, and small B/G ratios indicate that they are potential hard materials. Relative enthalpy calculations with respect to possible constituents are also investigated to assess the prospects for phase formation and an attempt at high-pressure synthesis is suggested to obtain chromium triboride

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

    Science.gov (United States)

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

    2011-02-01

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

  12. Fast phase stabilization of a low frequency beat note for atom interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Oh, E.; Horne, R. A.; Sackett, C. A., E-mail: sackett@virginia.edu [Department of Physics, University of Virginia, 382 McCormick Road, Charlottesville, Virginia 22904-4714 (United States)

    2016-06-15

    Atom interferometry experiments rely on the ability to obtain a stable signal that corresponds to an atomic phase. For interferometers that use laser beams to manipulate the atoms, noise in the lasers can lead to errors in the atomic measurement. In particular, it is often necessary to actively stabilize the optical phase between two frequency components of the beams. Typically this is achieved using a time-domain measurement of a beat note between the two frequencies. This becomes challenging when the frequency difference is small and the phase measurement must be made quickly. The method presented here instead uses a spatial interference detection to rapidly measure the optical phase for arbitrary frequency differences. A feedback system operating at a bandwidth of about 10 MHz could then correct the phase in about 3 μs. This time is short enough that the phase correction could be applied at the start of a laser pulse without appreciably degrading the fidelity of the atom interferometer operation. The phase stabilization system was demonstrated in a simple atom interferometer measurement of the {sup 87}Rb recoil frequency.

  13. Phase stability and decomposition processes in Ti-Al based intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Nakai, Kiyomichi [Department of Materials Science and Engineering, Faculty of Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama 790 (Japan); Ono, Toshiaki [Department of Materials Science and Engineering, Faculty of Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama 790 (Japan); Ohtsubo, Hiroyuki [Department of Materials Science and Engineering, Faculty of Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama 790 (Japan); Ohmori, Yasuya [Department of Materials Science and Engineering, Faculty of Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama 790 (Japan)

    1995-02-28

    The high-temperature phase equilibria and the phase decomposition of {alpha} and {beta} phases were studied by crystallographic analysis of the solidification microstructures of Ti-48at.%Al and Ti-48at.%Al-2at.%X (X=Mn, Cr, Mo) alloys. The effects on the phase stability of Zr and O atoms penetrating from the specimen surface were also examined for Ti-48at.%Al and Ti-50at.%Al alloys. The third elements Cr and Mo shift the {beta} phase region to higher Al concentrations, and the {beta} phase is ordered to the {beta}{sub 2} phase. The Zr and O atoms stabilize {beta} and {alpha} phases respectively. In the Zr-stabilized {beta} phase, {alpha}{sub 2} laths form with accompanying surface relief, and stacking faults which relax the elastic strain owing to lattice deformation are introduced after formation of {alpha}{sub 2} order domains. Thus shear is thought to operate after the phase transition from {beta} to {alpha}{sub 2} by short-range diffusion. A similar analysis was conducted for the Ti-Al binary system, and the transformation was interpreted from the CCT diagram constructed qualitatively. ((orig.))

  14. Investigation of phase stability and oxide ion performance in new perovskite-type bismuth vanadate

    International Nuclear Information System (INIS)

    Al-Alas, Ahlam; Beg, Saba; Al-Areqi, Niyazi A.S.

    2012-01-01

    Samples of the BICDVOX system, formulated as Bi 4 Cd x V 2−x O 11−(3x/2)−δ in the Cd substitution range 0 ≤ x ≤ 0.25 were synthesized using the standard solid state reaction.The correlation between phase stability and oxide ion performance were investigated by variable temperature XRPD, DSC and AC impedance spectroscopy. The substitution of V 5+ by Cd 2+ exhibited different phase transitions upon varying composition. For compositions with x ≤ 0.05, two successive transitions; α↔β↔γ are evident, while the β↔γ transition exists in the composition range 0.05 4+ → V 5+ re–oxidation results in increased defect trapping effects in the system at higher temperatures. -- Highlights: ► γ-Stabilized BICDVOX at lower dopant concentrations. ► Good oxide-ion conductivity at lower temperatures. ► High temperature-vanadium reduction with lower dopant concentrations.

  15. Study on phase stability and ionic conductivity in HfIV-substituted bismuth vanadate

    International Nuclear Information System (INIS)

    Beg, Saba; Al-Areqi, Niyazi A.S.

    2009-01-01

    Influence of dopant concentration on thermal behaviour of Bi 4 Hf x V 2-x O 11-(x/2)-δ was studied over composition range 0 ≤ x ≤ 0.40 by combination of data obtained from X-ray powder diffraction, differential scanning calorimetric and conductivity measurements. For very low dopant concentrations, the system was found to mimic the parent compound in exhibiting two consecutive transitions,α ↔ β ↔ γ, with slightly different onset temperatures compared to that of parent, whereas the existence of β ↔ γ transition was well confirmed in composition range 0.15 ≤ x ≤ 0.20 and typified in Arrhenius plots to two line regions of different activation energy. For composition range 0.25 ≤ x ≤ 0.40, no significant structural changes associated with γ' ↔ γ transition is visible in X-ray powder diffraction data with variable temperature. Despite this, the existence of γ' ↔ γ transition was evident by some complex incommensurate modulations observed in Arrhenius plots and DSC/DTA thermograms. It was surprising to note the appearance of a new destructive γ ↔ β' transition, resulting from distortion of the tetragonal phase structure at higher temperatures. The relationship between phase stability and ionic conductivity was also rationalized.

  16. Atomic ordering, phase stability and superconductivity in bulk and filamentary A15 type compounds

    International Nuclear Information System (INIS)

    Fluekiger, R.

    1987-05-01

    The influence of atomic ordering effects and ordering kinetics on the superconducting and metallurgical properties of A15 type compounds are critically discussed based on own and literature data. First, the techniques for determining the order parameter are reviewed. The dependence of T c vs. S in various A15 type compounds as a function of the quenching temperature and of the high energy particle irradiation fluence is discussed. A model for the disordering mechanism in A15 compounds is established, based on the new concept of the virtual lattice site. It is shown that the disordering mechanism is the same in both cases, high temperature heat treatment and high energy particle irradiation. The very complete representation of ordering effects also contains the variation of other properties, e.g. γ, θ D , ρ o and B c2 (0). Furthermore, it allows to draw empirical correlations between atomic ordering and A15 phase stability. Finally, it is shown on selected examples that the optimization of the critical current density at high fields in Nb 3 Sn wires by alloying is nothing else than a consequence of the occurrence of perfect atomic ordering in binary Nb 3 Sn. (orig.)

  17. Stochastic description of cascade size effects on phase stability under irradiation

    International Nuclear Information System (INIS)

    Martin, G.; Bellon, P.

    1988-01-01

    Cascade size may affect phase stability under irradiation because of two distinct contributions: the replacement to displacement cross section ratio depends on the deposited energy density; ballistic jumps which tend to disorder ordere compounds occur by bursts (of size b), while thermal jumps which restored long range order occur one by one. The latter effect cannot be handled by standard rate theory. A stochastic treatment of the problem, based on a Fokker Planck approximation of the relevant master equation is summarized. It is shown that the possible values of the long range order parameter under irradiation are not affected by the size b of the bursts, but that the respective stability of the former is b dependent. As a consequence, the stability diagram of phases under irradiation varies with b. Such a diagram is computed for the Ni 4 Mo system where three structures are competing: the disordered solid solution, D1 a and DO 23 . A broadening by 100K of the stability domain of the short range ordered structure to the expense of the long range ordered one is predicted when increasing b from 1 to 100. The stochastic potentials introduced in the present treatment are by no means free energies of some constrained state. They can however be computed in a mean field type approximation. 23 refs

  18. Thermodynamic calculations of AuxAg1−x – Fluid equilibria and their applications for ore-forming conditions

    International Nuclear Information System (INIS)

    Liang, Y.; Hoshino, K.

    2015-01-01

    Highlights: • Solubilities of Au–Ag solid solutions are calculated at wide conditions. • Ratios of dissolved Au and Ag depend only on pH at intermediate pH. • Fluid conditions for high gold finenesses have been examined. - Abstract: Concentrations of dissolved gold and silver species in hydrothermal fluids equilibrated with Au–Ag solid solutions have been calculated at wide conditions on the well known fO 2 –pH spaces. Ratios of the total concentrations of dissolved gold and silver species (∑Au/∑Ag) are higher as pH higher and fO 2 lower. The ratios are constant at very low and high pH conditions where major dissolved species of both gold and silver are chloride complexes and thio complexes, respectively, while the ratios practically depend only on pH at intermediate pH conditions where Au(HS) 2 − and AgCl 2 − are major. The calculated results indicate that the solid solutions of high gold finenesses may precipitate from the fluids of low ratios of the total concentrations of dissolved gold and silver species when the conditions are (1) low pH’s and/or (2) high concentration ratios of dissolved chlorine and sulfur and/or (3) high temperatures

  19. 氪等离子体热力学非平衡输运性质的计算%Calculation of Transport Properties of Krypton Plasma in Thermodynamic Nonequilibrium

    Institute of Scientific and Technical Information of China (English)

    孙素蓉; 王海兴

    2013-01-01

    获得覆盖较宽温度和压力范围内的热力学和输运性质是进行氪等离子体传热和流动过程研究的必要输入条件.为此,采用双温度Saha方程进行计算得到了氪等离子体的组分;采用基于将Chapman-Enskog方法扩展到高阶近似的方法,计算获得了电子温度(Te)与重粒子温度(Th)比范围为1~4、电子温度范围为300~30000K、压力范围从0.01p0~10p0(p0=101.325 kPa)的氪等离子体的粘性、热导率和电导率.研究结果表明,热力学非平衡参数(θ=Te/Th)和压力对氪等离子体的输运性质有较大的影响.随着压力的降低和热力学非平衡程度的增加,氪等离子体的粘性降低;偏离热力学非平衡的程度对热导率的峰值有显著影响,压力越大,高温区域的平动热导率就越大;高温区,电导率随着压力的升高而增大,在低温区,电导率随着压力的降低而增大.在局域热力学平衡条件下,计算获得的氪等离子体输运性质和文献报道的数据符合良好.%To study the plasma flow and heat transfer process,it is necessary to understand the two-temperature thermodynamics and transport properties of krypton plasma over wide temperature and pressure range.Therefore,assuming chemical equilibrium and using a method of equilibrium constants with a 2T modified Saha law,we calculated the composition of krypton plasma,and calculated transport coefficients by using Chapman-Enskog method which was expanded to higher approximation.Moreover,we computed the variations of viscosity,thermal conductivity,and electrical conductivity of krypton plasma as a function of temperature,pressure and different degree of temperature non-equilibrium.In the computation,the electron temperature ranges from 300 K to 30000 K,the ratio of electron temperature (Te) to the heavy particle temperature (Th) ranges from 1 to 4,and the pressure ranges within 0.01p0~10p0 (P0 =101.325 kPa,standard atmospheric pressures).It is shown that the

  20. 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.)

  1. Ecosystem thermodynamics

    International Nuclear Information System (INIS)

    Gomez Palacio, German Rau

    1998-01-01

    Ecology is no more a descriptive and self-sufficient science. Many viewpoints are needed simultaneously to give a full coverage of such complex systems: ecosystems. These viewpoints come from physics, chemistry, and nuclear physics, without a new far from equilibrium thermodynamics and without new mathematical tools such as catastrophe theory, fractal theory, cybernetics and network theory, the development of ecosystem science would never have reached the point of today. Some ideas are presented about the importance that concept such as energy, entropy, exergy information and none equilibrium have in the analysis of processes taking place in ecosystems

  2. Thermodynamic re-assessment of the Pu–U system and its application to the ternary Pu–U–Ga system

    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); Kurata, M. [JAEA, Nucl. Sci. and Engn. Directorate, Tokai, Ibaraki 3191195 (Japan)

    2014-11-15

    Highlights: • The ab initio aided CALPHAD assessment of the Pu–U system has been realized. • The Pu–U–Ga thermodynamic database has been developed. • The δ-phase (fcc) of the Pu–U–Ga system is stabilized by Ga. • The stability of the complex η and ζ phases is promoted by U in the Pu–U–Ga system. - Abstract: Phase diagram and thermodynamic properties of the Plutonium–Uranium (Pu–U) system have been successfully re-assessed using the CALPHAD method with input from ab initio electronic-structure calculations for the bcc phase (γ-U, ∊-Pu). Results and methodology are discussed and compared with previous assessments. In addition, the already assessed Pu–Ga (Gallium) and U–Ga data are combined to build the Pu–U–Ga thermodynamic database. The predictions made using this database indicate that a small amount of U impacts the (δ-Pu) Pu–Ga phase stability by precipitating the complicated η and ζ phases that exist in the Pu–U system. Finally, the present investigation provides guidelines for further experimental studies.

  3. A first principle study of phase stability, electronic structure and magnetic properties for Co{sub 2−x}Cr{sub x}MnAl Heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Rached, H. [Laboratoire des Matériaux Magnétiques, Faculté des Sciences exactes, Université Djillali Liabès de Sidi Bel-Abbès, Sidi Bel-Abbès 22000 (Algeria); Rached, D., E-mail: rachdj@yahoo.fr [Laboratoire des Matériaux Magnétiques, Faculté des Sciences exactes, Université Djillali Liabès de Sidi Bel-Abbès, Sidi Bel-Abbès 22000 (Algeria); Khenata, R. [Laboratoire de Physique Quantique et de Modélisation Mathématique de la Matière, (LPQ3M), Université de Mascara, Mascara 29000 (Algeria); Abidri, B.; Rabah, M.; Benkhettou, N. [Laboratoire des Matériaux Magnétiques, Faculté des Sciences exactes, Université Djillali Liabès de Sidi Bel-Abbès, Sidi Bel-Abbès 22000 (Algeria); Omran, S. Bin [Department of Physics and Astronomy, College of Science, King Saud University, P.O.Box 2455, Riyadh 11451 (Saudi Arabia)

    2015-04-01

    The structural stabilities, electronic and magnetic properties of Co{sub 2−x}Cr{sub x}MnAl alloys with (x=0,1 and 2) were investigated using the full-potential linear muffin-tin orbital (FP-LMTO) method, in the framework of the density functional theory (DFT) within the generalized gradient approximation (GGA) for the exchange correlation functional. The ground state properties including lattice parameter, bulk modulus for the two considered crystal structures Hg{sub 2}CuTi-Type (X-Type) and Cu{sub 2}MnAl-Type (L2{sub 1}-Type) are calculated. The half-metallicity within ferromagnetic ground state starts to appear in CoCrMnAl and Cr2MnAl. In the objective for the proposition of the new HM-FM in the Full-Heusler alloys, our results classified CoCrMnAl as new HM-FM material with high spin polarization. - Highlights: • Based on DFT calculations, Co2-xCrxMnAl Heusler alloys have been investigated. • The magnetic phase stability was determined from the total energy calculations. • The LMTO calculations have classified CoCrMnAl as new HM-FM material with high spin polarization.

  4. Advanced adsorption cooling cum desalination cycle: A thermodynamic framework

    KAUST Repository

    Chakraborty, Anutosh; Thu, Kyaw; Ng, K. C.

    2011-01-01

    We have developed a thermodynamic framework to calculate adsorption cooling cum desalination cycle performances as a function of pore widths and pore volumes of highly porous adsorbents, which are formulated from the rigor of thermodynamic property

  5. Phase stability in the Nb-rich region of the Nb-B-Si system

    Energy Technology Data Exchange (ETDEWEB)

    Nunes, C.A.; Coelho, G.C.; Pinto, D.M. Jr.; Camargo Gandolpho, K.C. de; Borges, L.A. Jr.; Rodrigues, G. [Polo Urbo-Ind., Gleba, Lorena (Brazil). Dept. de Engenharia de Materiais

    2000-07-01

    Alloys of the Me-B-Si systems (Me-refractory metal) have been evaluated due to their potential for use as high temperature structural materials (T>1400 C). In the present study, the phase stability in the Nb-rich region of the Nb-B-Si system has been evaluated in terms of the current information associated to the Nb-Si, Nb-B and Nb-B-Si systems as well as our own data. For the experiments several as-cast and heat-treated alloys of the Nb-B and Nb-B-Si systems were investigated by X-ray diffraction and scanning electron microscopy. Concerning the Nb-B system the results indicated the existence of the eutectic reaction L ({proportional_to} 16 at%B) <=> Nb{sub ss}+NbB. The Nb{sub 3}B{sub 2} phase was not observed in the microstructure of as-cast alloys with composition in the range of 0 to 50 at%B. The analysis of heat-treated ternary alloys at 1600 C and 1750 C confirmed the existence of the Nb{sub ss}+T{sub 2} two-phase field at those temperatures. This T{sub 2}-phase is isomorphous of the {alpha}Nb{sub 5}Si{sub 3} and is formed through the partial substitution of Si atomos for B atoms in the lattice of the {alpha}Nb{sub 5}Si{sub 3}-phase. All ternary alloys prepared in the present study presented either Nb{sub ss} or T{sub 2} primary phases in the as-cast microstructures. In addition, those alloys presented an eutectic-like microstructure formed by the Nb{sub ss} and T{sub 2} phases in the interdendritic region. (orig.)

  6. Contribution to the study of the thermodynamic properties of solutions using their phase diagrams (1961); Contribution au calcul des proprietes thermodynamiques des solutions a partir des diagrammes de phases (1961)

    Energy Technology Data Exchange (ETDEWEB)

    Hagege, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-10-15

    The thermodynamic study of the behaviour of solutions is of great interest in applied metallurgical problems, since the use of physical phenomena (solubility or volatility, for example) makes it possible to effect chemical reactions which, would not take place if the products formed did not mix. It is interesting to be able to predict this behaviour, at least for binary systems, using a knowledge of the phase diagrams. After showing the theoretical impossibility of resolving this problem without further data, an attempt is made to show what can be calculated from a knowledge of the phase diagrams: on the one hand it is possible to study the coherence between different types of data (calorimetric or equilibrium); on the other hand can be calculated the 'model' parameters, whether they be empirical, or statistically derived, and their validity can be checked. (author) [French] L'etude thermodynamique du comportement des solutions presente un grand interet dans les problemes de metallurgie appliquee puisque l'emploi de phenomenes physiques (solubilite ou volatilisation par exemple) permet de realiser des reactions chimiques qui seraient irrealisables si les produits formes ne se melangeaient pas. Il semble tres interessant de pouvoir prevoir ce comportement, tout au moins dans le cas de systemes binaires, a partir de la connaissance des diagrammes de phases. Apres avoir montre l'impossibilite theorique de resoudre ce probleme sans autres donnees, on essaie de voir ce que permet de calculer la connaissance des diagrammes de phases: d'une part, on peut etudier la coherenc entre divers types de donnees (calorimetrique ou d'equilibre); d'autre-part, on peut calculer les parametres de 'modeles', qu'ils soient empiriques ou a base statistique, et verifier leur validite. (auteur)

  7. Linear Discriminant Analysis for the in Silico Discovery of Mechanism-Based Reversible Covalent Inhibitors of a Serine Protease: Application of Hydration Thermodynamics Analysis and Semi-empirical Molecular Orbital Calculation.

    Science.gov (United States)

    Masuda, Yosuke; Yoshida, Tomoki; Yamaotsu, Noriyuki; Hirono, Shuichi

    2018-01-01

    We recently reported that the Gibbs free energy of hydrolytic water molecules (ΔG wat ) in acyl-trypsin intermediates calculated by hydration thermodynamics analysis could be a useful metric for estimating the catalytic rate constants (k cat ) of mechanism-based reversible covalent inhibitors. For thorough evaluation, the proposed method was tested with an increased number of covalent ligands that have no corresponding crystal structures. After modeling acyl-trypsin intermediate structures using flexible molecular superposition, ΔG wat values were calculated according to the proposed method. The orbital energies of antibonding π* molecular orbitals (MOs) of carbonyl C=O in covalently modified catalytic serine (E orb ) were also calculated by semi-empirical MO calculations. Then, linear discriminant analysis (LDA) was performed to build a model that can discriminate covalent inhibitor candidates from substrate-like ligands using ΔG wat and E orb . The model was built using a training set (10 compounds) and then validated by a test set (4 compounds). As a result, the training set and test set ligands were perfectly discriminated by the model. Hydrolysis was slower when (1) the hydrolytic water molecule has lower ΔG wat ; (2) the covalent ligand presents higher E orb (higher reaction barrier). Results also showed that the entropic term of hydrolytic water molecule (-TΔS wat ) could be used for estimating k cat and for covalent inhibitor optimization; when the rotational freedom of the hydrolytic water molecule is limited, the chance for favorable interaction with the electrophilic acyl group would also be limited. The method proposed in this study would be useful for screening and optimizing the mechanism-based reversible covalent inhibitors.

  8. GASP: A computer code for calculating the thermodynamic and transport properties for ten fluids: Parahydrogen, helium, neon, methane, nitrogen, carbon monoxide, oxygen, fluorine, argon, and carbon dioxide. [enthalpy, entropy, thermal conductivity, and specific heat

    Science.gov (United States)

    Hendricks, R. C.; Baron, A. K.; Peller, I. C.

    1975-01-01

    A FORTRAN IV subprogram called GASP is discussed which calculates the thermodynamic and transport properties for 10 pure fluids: parahydrogen, helium, neon, methane, nitrogen, carbon monoxide, oxygen, fluorine, argon, and carbon dioxide. The pressure range is generally from 0.1 to 400 atmospheres (to 100 atm for helium and to 1000 atm for hydrogen). The temperature ranges are from the triple point to 300 K for neon; to 500 K for carbon monoxide, oxygen, and fluorine; to 600 K for methane and nitrogen; to 1000 K for argon and carbon dioxide; to 2000 K for hydrogen; and from 6 to 500 K for helium. GASP accepts any two of pressure, temperature and density as input conditions along with pressure, and either entropy or enthalpy. The properties available in any combination as output include temperature, density, pressure, entropy, enthalpy, specific heats, sonic velocity, viscosity, thermal conductivity, and surface tension. The subprogram design is modular so that the user can choose only those subroutines necessary to the calculations.

  9. Structure, phase stability, and gaps of wurtzite MgZnO and CdZnO alloys

    International Nuclear Information System (INIS)

    Eisenacher, Matthias; Schleife, Andre; Furthmueller, Juergen; Bechstedt, Friedhelm; Kuehl Teles, Lara

    2008-01-01

    Recently II-VI compounds became more and more important as materials with potential applications in optoelectronic devices. For pseudomorphic heterostructures it is highly desirable to adjust the material properties carefully. Alloys allow to tailor a certain material property. Also from a theoretical point of view the investigation of mixed crystals is a challenge. We apply density functional theory and the generalized quasichemical approximation together with a cluster approximation to study MgZnO and CdZnO alloys in the wurtzite structure. The combination of these ab initio approaches enables us to study the thermodynamics of these systems as well as the structural and electronic properties with varying composition. We construct phase diagrams versus composition and temperature and calculate bond lengths as well as gap-bowing parameters for the two alloys versus average composition

  10. First Principles Thermodynamics of Minerals at HP–HT Conditions: MgO as a Prototypical Material

    Directory of Open Access Journals (Sweden)

    Donato Belmonte

    2017-09-01

    Full Text Available Ab initio thermodynamic properties, equation of state and phase stability of periclase (MgO, B1-type structure have been investigated in a broad P–T range (0–160 GPa; 0–3000 K in order to set a model reference system for phase equilibria simulations under deep Earth conditions. Phonon dispersion calculations performed on large supercells using the finite displacement method and in the framework of quasi-harmonic approximation highlight the performance of the Becke three-parameter Lee-Yang-Parr (B3LYP hybrid density functional in predicting accurate thermodynamic functions (heat capacity, entropy, thermal expansivity, isothermal bulk modulus and phase reaction boundaries at high pressure and temperature. A first principles Mie–Grüneisen equation of state based on lattice vibrations directly provides a physically-consistent description of thermal pressure and P–V–T relations without any need to rely on empirical parameters or other phenomenological formalisms that could give spurious anomalies or uncontrolled extrapolations at HP–HT. The post-spinel phase transformation, Mg2SiO4 (ringwoodite = MgO (periclase + MgSiO3 (bridgmanite, is taken as a computational example to illustrate how first principles theory combined with the use of hybrid functionals is able to provide sound results on the Clapeyron slope, density change and P–T location of equilibrium mineral reactions relevant to mantle dynamics.

  11. Development and application of the S/PHI/nX library. First-principles calculations of thermodynamic properties of III-V semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Boeck, Sixten

    2009-09-03

    which we developed in this work. In order to demonstrate the power of the this approach the full-featured plane-wave framework S/PHI/nX has been developed based on the new meta-language. The S/PHI/nX source code is remarkably short and transparent which simplifies code maintenance and the introduction of new sophisticated algorithms. Various benchmarks which have been conducted in this study compare S/PHI/nX with other state-of-the-art plane-wave packages with respect to runtime performance and accuracy. Based on these calculations we verified the general trends of phonon spectra, the location and amplitudes of the thermal anomalies of these systems. (orig.)

  12. Equilibrium thermodynamics

    CERN Document Server

    de Oliveira, Mário J

    2017-01-01

    This textbook provides an exposition of equilibrium thermodynamics and its applications to several areas of physics with particular attention to phase transitions and critical phenomena. The applications include several areas of condensed matter physics and include also a chapter on thermochemistry. Phase transitions and critical phenomena are treated according to the modern development of the field, based on the ideas of universality and on the Widom scaling theory. For each topic, a mean-field or Landau theory is presented to describe qualitatively the phase transitions. These theories include the van der Waals theory of the liquid-vapor transition, the Hildebrand-Heitler theory of regular mixtures, the Griffiths-Landau theory for multicritical points in multicomponent systems, the Bragg-Williams theory of order-disorder in alloys, the Weiss theory of ferromagnetism, the Néel theory of antiferromagnetism, the Devonshire theory for ferroelectrics and Landau-de Gennes theory of liquid crystals. This new edit...

  13. Study of the decomposition of phase stabilized ammonium nitrate (PSAN) by simultaneous thermal analysis: determination of kinetic parameters

    OpenAIRE

    Simões, P. N.; Pedroso, L. M.; Portugal, A. A.; Campos, J. L.

    1998-01-01

    Ammonium nitrate (AN) has been extensively used both in explosive and propellant formulations. Unlike AN, there is a lack of information about the thermal decomposition and related kinetic analysis of phase stabilized ammonium nitrate (PSAN). Simultaneous thermal analysis (DSC-TG) has been used in the thermal characterisation of a specific type of PSAN containing 1.0% of NiO (stabilizing agent) and 0.5% of Petro (anti-caking agent) as additives. Repeated runs covering the nominal heating rate...

  14. A first principles study of phase stability, bonding, electronic and lattice dynamical properties of beryllium chalcogenides at high pressure

    International Nuclear Information System (INIS)

    Dabhi, Shweta; Mankad, Venu; Jha, Prafulla K.

    2014-01-01

    Highlights: • First principles calculations are performed for BeS, BeSe and BeTe in B3, B8 and B1 phases. • They are indirect wide band gap semiconductors stable in B3 phase at ambient condition. • Phonon calculations at ambient and high pressure are reported. • The NiAs phase is dynamically stable at high pressure. - Abstract: The present paper reports a detailed and systematic theoretical study of structural, mechanical, electronic, vibrational and thermodynamical properties of three beryllium chalcogenides BeS, BeSe and BeTe in zinc blende, NiAs and rock salt phases by performing ab initio calculations based on density-functional theory. The calculated value of lattice constants and bulk modulus are compared with the available experimental and other theoretical data and found to agree reasonably well. These compounds are indirect wide band gap semiconductors with a partially ionic contribution in all considered three phases. The zinc blende phase of these chalcogenides is found stable at ambient condition and phase transition from zinc blende to NiAs structure is found to occur. The bulk modulus, its pressure derivative, anisotropic factor, Poission’s ratio, Young’s modulus for these are also calculated and discussed. The phonon dispersion curves of these beryllium chalcogenides in zinc blende phase depict their dynamical stability in this phase at ambient condition. We have also estimated the temperature variation of specific heat at constant volume, entropy and Debye temperature for these compounds in zinc blende phase. The variation of lattice-specific heat with temperature obeys the classical Dulong–Petit’s law at high temperature, while at low-temperature it obeys the Debye’s T 3 law

  15. Impact of phase stability on the corrosion behavior of the austenitic candidate materials for NNWSI [Nevada Nuclear Waste Storage Investigations

    International Nuclear Information System (INIS)

    Bullen, D.B.; Gdowski, G.E.; McCright, R.D.

    1987-10-01

    The Nuclear Waste Management Program at Lawrence Livermore National Laboratory is responsible for the development of the waste package design to meet the Nuclear Regulatory Commission licensing requirements for the Nevada Nuclear Waste Storage Investigations (NNWSI) Project. The metallic container component of the waste package is required to assist in providing substantially complete containment of the waste for a period of up to 1000 years. Long term phase stability of the austenitic candidate materials (304L and 316L stainless steels and alloy 825) over this time period at moderate temperatures (100-250 0 C) can impact the mechanical and corrosion behavior of the metal barrier. A review of the technical literature with respect to phase stability of 304L, 316L and 825 is presented. The impact of martensitic transformations, carbide precipitation and intermediate (σ, chi, and eta) phase formation on the mechanical properties and corrosion behavior of these alloys at repository relevant conditions is discussed. The effect of sensitization on intergranular stress corrosion cracking (IGSCC) of each alloy is also addressed. A summary of the impact of phase stability on the degradation of each alloy in the proposed repository environment is included. 32 refs., 6 figs

  16. Z phase stability in AISI 316LN + Nb austenitic steels during creep at 650 C

    Energy Technology Data Exchange (ETDEWEB)

    Vodarek, Vlastimil [Technical Univ. Ostrava (Czech Republic)

    2010-07-01

    The creep resistance of austenitic CrNi(Mo) steels strongly depends on microstructural stability during creep exposure. Nitrogen additions to CrNi(Mo) austenitic steels can significantly improve the creep strength. One of the most successful methods of improving the long-term creep resistance of austenitic steels is based on increasing the extent of precipitation strengthening during creep exposure. The role of precipitates in the achievements of good creep properties has been extensively studied for a long time. Although many minor phases are now well documented there are still contractions and missing thermodynamic data about some minor phases. This contribution deals with results of microstructural studies on the minor phase evolution in wrought AISI 316LN niobium stabilised steels during long-term creep exposure at 650 C. Microstructural investigations were carried out on specimens taken from both heads and gauge lengths of ruptured test-pieces by means of optical metallography, transmission and scanning electron microscopy. The attention has been paid to evaluation of thermodynamic and dimensional stability of Z phase and other nitrogen bearing minor phases. Only two nitrogen-bearing minor phases formed in the casts investigated: Z phase and M{sub 6}X. The dimensional stability of Z phase particles was very high. (orig.)

  17. Monte Carlo simulations for thermodynamical properties calculations of plasmas at thermodynamical equilibrium. Applications to opacity and equation of state calculations; Apport d'un code de simulation Monte Carlo pour l'etude des proprietes thermodynamiques d'un plasma a l'equilibre et application au calcul de l'elargissement des profils de raies ioniques emises dans les plasmas denses, aux opacites spectrales et aux equations d'etat de systemes fluides

    Energy Technology Data Exchange (ETDEWEB)

    Gilles, D

    2005-07-01

    This report is devoted to illustrate the power of a Monte Carlo (MC) simulation code to study the thermodynamical properties of a plasma, composed of classical point particles at thermodynamical equilibrium. Such simulations can help us to manage successfully the challenge of taking into account 'exactly' all classical correlations between particles due to density effects, unlike analytical or semi-analytical approaches, often restricted to low dense plasmas. MC simulations results allow to cover, for laser or astrophysical applications, a wide range of thermodynamical conditions from more dense (and correlated) to less dense ones (where potentials are long ranged type). Therefore Yukawa potentials, with a Thomas-Fermi temperature- and density-dependent screening length, are used to describe the effective ion-ion potentials. In this report we present two MC codes ('PDE' and 'PUCE') and applications performed with these codes in different fields (spectroscopy, opacity, equation of state). Some examples of them are discussed and illustrated at the end of the report. (author)

  18. An Experimental Determination of Thermodynamic Values

    Science.gov (United States)

    Antony, Erling; Muccianti, Christine; Vogel, Tracy

    2012-01-01

    Measurements have been added to an old demonstration of chemical equilibria allowing the determination of thermodynamic constants. The experiment allows the students an opportunity to merge qualitative observations associated with Le Chatelier's principle and thermodynamic calculations using graphical techniques. (Contains 4 figures.)

  19. Molecular structure and conformational composition of 1,3-dihydroxyacetone studied by combined analysis of gas-phase electron diffraction data, rotational constants, and results of theoretical calculations. Ideal gas thermodynamic properties of 1,3-dihydroxyacetone.

    Science.gov (United States)

    Dorofeeva, Olga V; Vogt, Natalja; Vogt, Jürgen; Popik, Mikhail V; Rykov, Anatolii N; Vilkov, Lev V

    2007-07-19

    The molecular structure of 1,3-dihydroxyacetone (DHA) has been studied by gas-phase electron diffraction (GED), combined analysis of GED and microwave (MW) data, ab initio, and density functional theory calculations. The equilibrium re structure of DHA was determined by a joint analysis of the GED data and rotational constants taken from the literature. The anharmonic vibrational corrections to the internuclear distances (re-ra) and to the rotational constants (B(i)e-B(i)0) needed for the estimation of the re structure were calculated from the B3LYP/cc-pVTZ cubic force field. It was found that the experimental data are well reproduced by assuming that DHA consists of a mixture of three conformers. The most stable conformer of C2v symmetry has two hydrogen bonds, whereas the next two lowest energy conformers (Cs and C1 symmetry) have one hydrogen bond and their abundance is about 30% in total. A combined analysis of GED and MW data led to the following equilibrium structural parameters (re) of the most abundant conformer of DHA (the uncertainties in parentheses are 3 times the standard deviations): r(C=O)=1.215(2) A, r(C-C)=1.516(2) A, r(C-O)=1.393(2) A, r(C-H)=1.096(4) A, r(O-H)=0.967(4) A, angleC-C=O=119.9(2) degrees, angleC-C-O=111.0(2) degrees, angleC-C-H=108.2(7) degrees, angleC-O-H=106.5(7) degrees. These structural parameters reproduce the experimental B(i)0 values within 0.05 MHz. The experimental structural parameters are in good agreement with those obtained from theoretical calculations. Ideal gas thermodynamic functions (S degrees (T), C degrees p(T), and H degrees (T)-H degrees (0)) of DHA were calculated on the basis of experimental and theoretical molecular parameters obtained in this work. The enthalpy of formation of DHA, -523+/-4 kJ/mol, was calculated by the atomization procedure using the G3X method.

  20. Thermodynamics of freezing and melting

    DEFF Research Database (Denmark)

    Pedersen, Ulf Rørbæk; Costigliola, Lorenzo; Bailey, Nicholas

    2016-01-01

    phases at a single thermodynamic state point provide the basis for calculating the pressure, density and entropy of fusion as functions of temperature along the melting line, as well as the variation along this line of the reduced crystalline vibrational mean-square displacement (the Lindemann ratio...

  1. Thermodynamics of Oligonucleotide Duplex Melting

    Science.gov (United States)

    Schreiber-Gosche, Sherrie; Edwards, Robert A.

    2009-01-01

    Melting temperatures of oligonucleotides are useful for a number of molecular biology applications, such as the polymerase chain reaction (PCR). Although melting temperatures are often calculated with simplistic empirical equations, application of thermodynamics provides more accurate melting temperatures and an opportunity for students to apply…

  2. First approach for thermodynamic modelling of the high temperature oxidation behaviour of ternary γ′-strengthened Co–Al–W superalloys

    International Nuclear Information System (INIS)

    Klein, L.; Zendegani, A.; Palumbo, M.; Fries, S.G.; Virtanen, S.

    2014-01-01

    Highlights: • Thermodynamic modelling of the oxidation behaviour of a novel Co-base superalloy. • Calculated oxide layer sequence is in good agreement with formed oxide scales. • Prediction of an optimised alloy composition with increased phase stability. • Prediction of the influence of oxygen partial pressure on Al 2 O 3 formation. - Abstract: In the present work, thermodynamic modelling of the high temperature oxidation behaviour of a γ′-strengthened Co-base superalloy is presented. The ternary Co–9Al–9W alloy (values in at%) was isothermally oxidised for 500 h at 800 and 900 °C in air. Results reveal that the calculated oxide layer sequence (Thermo-Calc, TCNI6) is in good agreement with the formed oxide scales on the alloy surface. Furthermore, prediction of the influence of oxygen partial pressure on Al 2 O 3 formation is presented. The modelling results indicate pathways for alloy development or possible pre-oxidation surface treatments for improved oxidation resistance of the material

  3. Thermodynamic Database for Zirconium Alloys

    International Nuclear Information System (INIS)

    Jerlerud Perez, Rosa

    2003-05-01

    For many decades zirconium alloys have been commonly used in the nuclear power industry as fuel cladding material. Besides their good corrosion resistance and acceptable mechanical properties the main reason of using these alloys is the low neutron absorption. Zirconium alloys are exposed to a very severe environment during the nuclear fission process and there is a demand for better design of this material. To meet this requirement a thermodynamic database is developed to support material designers. In this thesis some aspects about the development of a thermodynamic database for zirconium alloys are presented. A thermodynamic database represents an important facility in applying thermodynamic equilibrium calculations for a given material providing: 1) relevant information about the thermodynamic properties of the alloys e.g. enthalpies, activities, heat capacity, and 2) significant information for the manufacturing process e.g. heat treatment temperature. The basic information in the database is first the unary data, i.e. pure elements; those are taken from the compilation of the Scientific Group Thermodata Europe (SGTE) and then the binary and ternary systems. All phases present in those binary and ternary systems are described by means of the Gibbs energy dependence on composition and temperature. Many of those binary systems have been taken from published or unpublished works and others have been assessed in the present work. All the calculations have been made using Thermo C alc software and the representation of the Gibbs energy obtained by applying Calphad technique

  4. Defect structure, nonstoichiometry, and phase stability of Ca-doped YCrO3

    International Nuclear Information System (INIS)

    Carini, G.F. II; Anderson, H.U.; Nasrallah, M.M.; Sparlin, D.M.

    1991-01-01

    The dependence of the defect structure of Ca-doped YCrO 3 on oxygen activity and temperature was investigated by high temperature thermogravimetric measurements. Defect models developed from electrical conductivity data obtained in a previous study were used to interpret the thermogravimetric data. A correlation was found between the electrical conductivity and the thermogravimetric data which suggested that these data were concomitantly dependent on the acceptor dopant and oxygen vacancy dependence of the thermodynamic parameters. Kroeger-Vink type diagrams showing the regions of stability with respect to oxygen activity and temperature were constructed. The TGA data show that Ca-doped YCrO 3 is even more stable toward reduction than doped LaCrO 3

  5. Thermodynamics of Radiation Modes

    Science.gov (United States)

    Pina, Eduardo; de la Selva, Sara Maria Teresa

    2010-01-01

    We study the equilibrium thermodynamics of the electromagnetic radiation in a cavity of a given volume and temperature. We found three levels of description, the thermodynamics of one mode, the thermodynamics of the distribution of frequencies in a band by summing over the frequencies in it and the global thermodynamics by summing over all the…

  6. Ammonia-water system : Part I. Thermodynamic properties

    International Nuclear Information System (INIS)

    Goomer, N.C.; Dave, S.M.; Sadhukhan, H.K.

    1980-01-01

    The various thermodynamic properties which have direct bearing on design calculations and separation factor calculations for gaseous ammonia water system have been calculated and compiled in tabular form for easy reference. (auth.)

  7. Mathematical foundations of thermodynamics

    CERN Document Server

    Giles, R; Stark, M; Ulam, S

    2013-01-01

    Mathematical Foundations of Thermodynamics details the core concepts of the mathematical principles employed in thermodynamics. The book discusses the topics in a way that physical meanings are assigned to the theoretical terms. The coverage of the text includes the mechanical systems and adiabatic processes; topological considerations; and equilibrium states and potentials. The book also covers Galilean thermodynamics; symmetry in thermodynamics; and special relativistic thermodynamics. The book will be of great interest to practitioners and researchers of disciplines that deal with thermodyn

  8. Thermodynamics of 2D string theory

    International Nuclear Information System (INIS)

    Alexandrov, Sergei Yu.; V.A. Fock Department of Theoretical Physics, St. Petersburg University

    2003-01-01

    We calculate the free energy, energy and entropy in the matrix quantum mechanical formulation of 2D string theory in a background strongly perturbed by tachyons with the imaginary minkowskian momentum ±i/R ('Sine-Liouville' theory). The system shows a thermodynamical behaviour corresponding to the temperature T={1/(2π R)}. We show that the microscopically calculated energy of the system satisfies the usual thermodynamical relations and leads to a non-zero entropy. (author)

  9. 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

  10. 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

  11. Structures, phase stabilities, and electrical potentials of Li-Si battery anode materials

    KAUST Repository

    Tipton, William W.; Bealing, Clive R.; Mathew, Kiran; Hennig, Richard G.

    2013-01-01

    of composition, and a genetic algorithm coupled to density-functional theory searches the Li-Si binary phase diagram for small-cell, metastable crystal structures. Calculations of the phonon densities of states using density-functional perturbation theory

  12. Thermodynamic tables to accompany Modern engineering thermodynamics

    CERN Document Server

    Balmer, Robert T

    2011-01-01

    This booklet is provided at no extra charge with new copies of Balmer's Modern Engineering Thermodynamics. It contains two appendices. Appendix C contains 40 thermodynamic tables, and Appendix D consists of 6 thermodynamic charts. These charts and tables are provided in a separate booklet to give instructors the flexibility of allowing students to bring the tables into exams. The booklet may be purchased separately if needed.

  13. Classical and statistical thermodynamics

    CERN Document Server

    Rizk, Hanna A

    2016-01-01

    This is a text book of thermodynamics for the student who seeks thorough training in science or engineering. Systematic and thorough treatment of the fundamental principles rather than presenting the large mass of facts has been stressed. The book includes some of the historical and humanistic background of thermodynamics, but without affecting the continuity of the analytical treatment. For a clearer and more profound understanding of thermodynamics this book is highly recommended. In this respect, the author believes that a sound grounding in classical thermodynamics is an essential prerequisite for the understanding of statistical thermodynamics. Such a book comprising the two wide branches of thermodynamics is in fact unprecedented. Being a written work dealing systematically with the two main branches of thermodynamics, namely classical thermodynamics and statistical thermodynamics, together with some important indexes under only one cover, this treatise is so eminently useful.

  14. Theoretical simulations of the structural stabilities, elastic, thermodynamic and electronic properties of Pt3Sc and Pt3Y compounds

    Science.gov (United States)

    Boulechfar, R.; Khenioui, Y.; Drablia, S.; Meradji, H.; Abu-Jafar, M.; Omran, S. Bin; Khenata, R.; Ghemid, S.

    2018-05-01

    Ab-initio calculations based on density functional theory have been performed to study the structural, electronic, thermodynamic and mechanical properties of intermetallic compounds Pt3Sc and Pt3Y using the full-potential linearized augmented plane wave(FP-LAPW) method. The total energy calculations performed for L12, D022 and D024 structures confirm the experimental phase stability. Using the generalized gradient approximation (GGA), the values of enthalpies formation are -1.23 eV/atom and -1.18 eV/atom for Pt3Sc and Pt3Y, respectively. The densities of states (DOS) spectra show the existence of a pseudo-gap at the Fermi level for both compounds which indicate the strong spd hybridization and directing covalent bonding. Furthermore, the density of states at the Fermi level N(EF), the electronic specific heat coefficient (γele) and the number of bonding electrons per atom are predicted in addition to the elastic constants (C11, C12 and C44). The shear modulus (GH), Young's modulus (E), Poisson's ratio (ν), anisotropy factor (A), ratio of B/GH and Cauchy pressure (C12-C44) are also estimated. These parameters show that the Pt3Sc and Pt3Y are ductile compounds. The thermodynamic properties were calculated using the quasi-harmonic Debye model to account for their lattice vibrations. In addition, the influence of the temperature and pressure was analyzed on the heat capacities (Cp and Cv), thermal expansion coefficient (α), Debye temperature (θD) and Grüneisen parameter (γ).

  15. Nature of low dimensional structural modulations and relative phase stability in RexMo(W)1-xS2 transition metal dichalcogenide alloys

    KAUST Repository

    Sahu, R.

    2017-03-08

    We report on the various types of Peierls like two dimensional structural modulations and relative phase stability of 2H and 1T poly-types in the RexMo1-xS2 and RexW1-xS2 alloy system. Theoretical calculation predicts a polytype phase transition cross over at ∼50 at. % of Mo and W in ReS2 in both monolayer and bulk form, respectively. Experimentally, two different types of structural modulations at 50% and a modulation corresponding to trimerization at 75% alloy composition are observed for RexMo1-xS2 and only one type of modulation is observed at the 50% RexW1-xS2 alloy system. The 50% alloy system is found to be a suitable monolithic candidate for metal semiconductor transition with minute external perturbation. ReS2 is known to be in the 2D Peierls distorted 1Td structure and forms a chain like superstructure. Incorporation of Mo and W atoms into the ReS2 lattice modifies the metal-metal hybridization between the cations and influences the structural modulation and electronic properties of the system. The results offer yet another effective way to tune the electronic structure and poly-type phases of this class of materials other than intercalation, strain, and vertical stacking arrangement.

  16. Influence of Si and N additions on structure and phase stability of Ge{sub 2}Sb{sub 2}Te{sub 5} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Koelpin, Helmut; Music, Denis; Mykhaylonka, Ruslan; Schneider, Jochen M [Materials Chemistry, RWTH Aachen University, D-52056 Aachen (Germany); Laptyeva, Galyna; Ghadimi, Reza; Richter, Silvia; Mayer, Joachim [Central Facility for Electron Microscopy, RWTH Aachen University, Ahornstrasse 55, D-52074 Aachen (Germany); Merget, Florian [Institute of Semiconductor Electronics, RWTH Aachen University, Sommerfeldstrasse 24, D-52074 Aachen (Germany)

    2009-10-28

    The influence of Si and N in Ge{sub 2}Sb{sub 2}Te{sub 5} (space group Fm3-barm) on structure and phase stability thereof was studied experimentally by thin film growth and characterization as well as theoretically by ab initio calculations. It was found that Si and N most probably accumulate in the amorphous matrix embedding Ge{sub 2}Sb{sub 2}Te{sub 5} grains. The incorporation of Si and N in these samples causes an increase of the crystallization temperature and the formation of finer grains. N is more efficient in increasing the crystallization temperature and in reducing the grain size than Si which can be understood based on the bonding analysis. The incorporation of both Si and N in Ge{sub 2}Sb{sub 2}Te{sub 5} is energetically unfavourable, leading to finer grains and larger crystallization temperatures. While in the case of Si additions no significant changes in bonding are observed, N additions appear to enable the formation of strong Te-N bonds in the amorphous matrix, which are shown to be almost twice as strong as the strongest bonds in unalloyed Ge{sub 2}Sb{sub 2}Te{sub 5}.

  17. Investigation of phase stability of novel equiatomic FeCoNiCuZn based-high entropy alloy prepared by mechanical alloying

    Science.gov (United States)

    Soni, Vinay Kumar; Sanyal, S.; Sinha, S. K.

    2018-05-01

    The present work reports the structural and phase stability analysis of equiatomic FeCoNiCuZn High entropy alloy (HEA) systems prepared by mechanical alloying (MA) method. In this research effort some 1287 alloy combinations were extensively studied to arrive at most favourable combination. FeCoNiCuZn based alloy system was selected on the basis of physiochemical parameters such as enthalpy of mixing (ΔHmix), entropy of mixing (ΔSmix), atomic size difference (ΔX) and valence electron concentration (VEC) such that it fulfils the formation criteria of stable multi component high entropy alloy system. In this context, we have investigated the effect of novel alloying addition in view of microstructure and phase formation aspect. XRD plots of the MA samples shows the formation of stable solid solution with FCC (Face Cantered Cubic) after 20 hr of milling time and no indication of any amorphous or intermetallic phase formation. Our results are in good agreement with calculation and analysis done on the basis of physiochemical parameters during selection of constituent elements of HEA.

  18. Thermodynamically consistent model calibration in chemical kinetics

    Directory of Open Access Journals (Sweden)

    Goutsias John

    2011-05-01

    Full Text Available Abstract Background The dynamics of biochemical reaction systems are constrained by the fundamental laws of thermodynamics, which impose well-defined relationships among the reaction rate constants characterizing these systems. Constructing biochemical reaction systems from experimental observations often leads to parameter values that do not satisfy the necessary thermodynamic constraints. This can result in models that are not physically realizable and may lead to inaccurate, or even erroneous, descriptions of cellular function. Results We introduce a thermodynamically consistent model calibration (TCMC method that can be effectively used to provide thermodynamically feasible values for the parameters of an open biochemical reaction system. The proposed method formulates the model calibration problem as a constrained optimization problem that takes thermodynamic constraints (and, if desired, additional non-thermodynamic constraints into account. By calculating thermodynamically feasible values for the kinetic parameters of a well-known model of the EGF/ERK signaling cascade, we demonstrate the qualitative and quantitative significance of imposing thermodynamic constraints on these parameters and the effectiveness of our method for accomplishing this important task. MATLAB software, using the Systems Biology Toolbox 2.1, can be accessed from http://www.cis.jhu.edu/~goutsias/CSS lab/software.html. An SBML file containing the thermodynamically feasible EGF/ERK signaling cascade model can be found in the BioModels database. Conclusions TCMC is a simple and flexible method for obtaining physically plausible values for the kinetic parameters of open biochemical reaction systems. It can be effectively used to recalculate a thermodynamically consistent set of parameter values for existing thermodynamically infeasible biochemical reaction models of cellular function as well as to estimate thermodynamically feasible values for the parameters of new

  19. Martensitic transformation, fcc and hcp relative phase stability, and thermal cycling effects in Fe-Mn and Fe-Mn-X Alloys (X = Si, Co)

    International Nuclear Information System (INIS)

    Baruj, Alberto

    1999-01-01

    In this Thesis we present a study of the fcc and hcp relative phase stability in the Fe-Mn and Fe-Mn-Co systems. In particular, we have investigated the effect of two main factors affecting the relative phase stability: changes in the chemical composition of the alloys and changes in the density of crystalline defects in the microstructure.In order to analyse the effect of chemical composition, we have performed an experimental study of the fcc/hcp martensitic transformation temperatures in Fe-Mn-Co alloys in the composition range lying between 15% and 34% Mn, and between 1% and 16% Co.We have measured the martensitic transformation temperatures by means of dilatometry and electrical resistivity.We have combined this information with measurements of the fcc/hcp martensitic transformation temperatures in Co-rich alloys to perform a modelling of the Gibbs energy function for the hcp phase in the Fe-Mn-Co and Fe-Co systems.We found that, for alloys in the Mn range between 17% and 25%, Co additions tend to stabilise slightly the fcc phase.In the alloys with Mn contents below that range, increasing the amount of Co stabilise the bcc phase. In alloys with Mn contents above 25% the Neel temperature is depressed by the addition of Co, which stabilise the hcp phase.In order to investigate the effect of changes in the density of crystalline defects, we have performed thermal cycling experiments through the fcc/hcp martensitic transformation in Fe-Mn, Fe-Mn-Co and Fe-Mn-Si alloys.We have applied the thermodynamic description obtained before in order to analyse these experiments.We found in the thermal cycling experiments a first stage where the martensitic transformation is promoted.This stage occurs in all the studied alloys during the first cycle or the two first cycles.Increasing the number of thermal cycles, the promotion stage is replaced by an inhibition of the transformation stage.We propose a possible microstructural interpretation of these phenomena where the plastic

  20. Thermodynamic behaviour of ruthenium at high temperatures

    International Nuclear Information System (INIS)

    Garisto, F.

    1988-01-01

    Thermodynamic equilibrium calculations are used to determine the chemical speciation of ruthenium under postulated reactor accident conditions. The speciation of ruthenium is determined for various values of temperature, pressure, oxygen partial pressure and ruthenium concentration. The importance of these variables, in particular the oxygen partial pressure, in determining the volatility of ruthenium is clearly demonstrated in this report. Reliable thermodynamic data are required to determine the behaviour of ruthenium using equilibrium calculations. Therefore, it was necessary to compile a thermodynamic database for the ruthenium species that can be formed under reactor accident conditions. The origin of the thermodynamic data for the ruthenium species included in our calculations is discussed in detail in Appendix A. 23 refs

  1. Phase stability, physical properties of rhenium diboride under high pressure and the effect of metallic bonding on its hardness

    International Nuclear Information System (INIS)

    Zhong, Ming-Min; Kuang, Xiao-Yu; Wang, Zhen-Hua; Shao, Peng; Ding, Li-Ping; Huang, Xiao-Fen

    2013-01-01

    Highlights: •The transition pressure P t between the ReB 2 –ReB 2 and MoB 2 –ReB 2 phases is firstly determinate. •The single-bonded B–B feather remains in ReB 2 compounds. •A semiempirical method to evaluate the hardness of crystals with partial metallic bond is presented. •The large hardness (39.1 GPa) of ReB 2 –ReB 2 indicate that it is a superhard material. •The zigzag interconnected B–Re and B–B covalent bonds underlie the ultraincompressibilities. -- Abstract: Using first-principles calculations, the elastic constants, thermodynamic property and structural phase transition of rhenium diboride under pressure are investigated by means of the pseudopotential plane-waves method, as well as the effect of metallic bond on its hardness. Eight candidate structures of known transition-metal compounds are chosen to probe for rhenium diboride ReB 2 . The calculated lattice parameters are consistent with the experimental and theoretical values. Based on the third order Birch–Murnaghan equation of states, the transition pressure P t between the ReB 2 –ReB 2 and MoB 2 –ReB 2 phases is firstly determinate. Elastic constants, shear modulus, Young’s modulus, Poisson’s ratio and Debye temperature are derived. The single-bonded B–B feather remains in ReB 2 compounds. Furthermore, according to Mulliken overlap population analysis, a semiempirical method to evaluate the hardness of multicomponent crystals with partial metallic bond is presented. Both strong covalency and a zigzag topology of interconnected bonds underlie the ultraincompressibilities. In addition, the superior performance and large hardness (39.1 GPa) of ReB 2 –ReB 2 indicate that it is a superhard material

  2. Thermodynamics of geothermal fluids

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, P.S.Z.

    1981-03-01

    A model to predict the thermodynamic properties of geothermal brines, based on a minimum amount of experimental data on a few key systems, is tested. Volumetric properties of aqueous sodium chloride, taken from the literature, are represented by a parametric equation over the range 0 to 300{sup 0}C and 1 bar to 1 kbar. Density measurements at 20 bar needed to complete the volumetric description also are presented. The pressure dependence of activity and thermal properties, derived from the volumetric equation, can be used to complete an equation of state for sodium chloride solutions. A flow calorimeter, used to obtain heat capacity data at high temperatures and pressures, is described. Heat capacity measurements, from 30 to 200{sup 0}C and 1 bar to 200 bar, are used to derive values for the activity coefficient and other thermodynamic properties of sodium sulfate solutions as a function of temperature. Literature data on the solubility of gypsum in mixed electrolyte solutions have been used to evaluate model parameters for calculating gypsum solubility in seawater and natural brines. Predictions of strontium and barium sulfate solubility in seawater also are given.

  3. Chemical thermodynamic representation of

    International Nuclear Information System (INIS)

    Lindemer, T.B.; Besmann, T.M.

    1984-01-01

    The entire data base for the dependence of the nonstoichiometry, x, on temperature and chemical potential of oxygen (oxygen potential) was retrieved from the literature and represented. This data base was interpreted by least-squares analysis using equations derived from the classical thermodynamic theory for the solid solution of a solute in a solvent. For hyperstoichiometric oxide at oxygen potentials more positive than -266700 + 16.5T kJ/mol, the data were best represented by a [UO 2 ]-[U 3 O 7 ] solution. For O/U ratios above 2 and oxygen potentials below this boundary, a [UO 2 ]-[U 2 O 4 . 5 ] solution represented the data. The data were represented by a [UO 2 ]-[U 1 / 3 ] solution. The resulting equations represent the experimental ln(PO 2 ) - ln(x) behavior and can be used in thermodynamic calculations to predict phase boundary compositions consistent with the literature. Collectively, the present analysis permits a mathematical representation of the behavior of the total data base

  4. Effect of Co on the magnetism and phase stability of lithiated ...

    Indian Academy of Sciences (India)

    Unknown

    The corresponding cell contains 4 for- mula units, or 16 atoms. Calculations were also per- formed for the unalloyed systems, with x = 0. Diffraction measurements on (other than layered) sys- tems with composition LixMnO2 show a commensurate antiferromagnetic structure in the orthorhombic phase. (Greedan et al 1997) ...

  5. Thermodynamic theory of equilibrium fluctuations

    International Nuclear Information System (INIS)

    Mishin, Y.

    2015-01-01

    The postulational basis of classical thermodynamics has been expanded to incorporate equilibrium fluctuations. The main additional elements of the proposed thermodynamic theory are the concept of quasi-equilibrium states, a definition of non-equilibrium entropy, a fundamental equation of state in the entropy representation, and a fluctuation postulate describing the probability distribution of macroscopic parameters of an isolated system. Although these elements introduce a statistical component that does not exist in classical thermodynamics, the logical structure of the theory is different from that of statistical mechanics and represents an expanded version of thermodynamics. Based on this theory, we present a regular procedure for calculations of equilibrium fluctuations of extensive parameters, intensive parameters and densities in systems with any number of fluctuating parameters. The proposed fluctuation formalism is demonstrated by four applications: (1) derivation of the complete set of fluctuation relations for a simple fluid in three different ensembles; (2) fluctuations in finite-reservoir systems interpolating between the canonical and micro-canonical ensembles; (3) derivation of fluctuation relations for excess properties of grain boundaries in binary solid solutions, and (4) derivation of the grain boundary width distribution for pre-melted grain boundaries in alloys. The last two applications offer an efficient fluctuation-based approach to calculations of interface excess properties and extraction of the disjoining potential in pre-melted grain boundaries. Possible future extensions of the theory are outlined.

  6. 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.

  7. 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)

  8. Thermodynamics in Einstein's thought

    International Nuclear Information System (INIS)

    Klein, M.J.

    1983-01-01

    The role of the thermodynamical approach in the Einstein's scientific work is analyzed. The Einstein's development of a notion about statistical fluctuations of thermodynamical systems that leads him to discovery of corpuscular-wave dualism is retraced

  9. Development of a Knowledge Base of Ti-Alloys From First-Principles and Thermodynamic Modeling

    Science.gov (United States)

    Marker, Cassie

    An aging population with an active lifestyle requires the development of better load-bearing implants, which have high levels of biocompatibility and a low elastic modulus. Titanium alloys, in the body centered cubic phase, are great implant candidates, due to their mechanical properties and biocompatibility. The present work aims at investigating the thermodynamic and elastic properties of bcc Tialloys, using the integrated first-principles based on Density Functional Theory (DFT) and the CALculation of PHAse Diagrams (CALPHAD) method. The use of integrated first-principles calculations based on DFT and CALPHAD modeling has greatly reduced the need for trial and error metallurgy, which is ineffective and costly. The phase stability of Ti-alloys has been shown to greatly affect their elastic properties. Traditionally, CALPHAD modeling has been used to predict the equilibrium phase formation, but in the case of Ti-alloys, predicting the formation of two metastable phases o and alpha" is of great importance as these phases also drastically effect the elastic properties. To build a knowledge base of Ti-alloys, for biomedical load-bearing implants, the Ti-Mo-Nb-Sn-Ta-Zr system was studied because of the biocompatibility and the bcc stabilizing effects of some of the elements. With the focus on bcc Ti-rich alloys, a database of thermodynamic descriptions of each phase for the pure elements, binary and Ti-rich ternary alloys was developed in the present work. Previous thermodynamic descriptions for the pure elements were adopted from the widely used SGTE database for global compatibility. The previous binary and ternary models from the literature were evaluated for accuracy and new thermodynamic descriptions were developed when necessary. The models were evaluated using available experimental data, as well as the enthalpy of formation of the bcc phase obtained from first-principles calculations based on DFT. The thermodynamic descriptions were combined into a database

  10. Structural phase stability of ThSb and ThAs under pressure

    International Nuclear Information System (INIS)

    Venkatasubramaniam, K.; Rajagopalan, M.; Palanivel, B.; Kalpana, G.

    1997-01-01

    The high-pressure behaviour of thorium monopnictides is of considerable interest as these systems exhibit structural phase transitions under pressure. At ambient conditions these compounds crystallize in the NaCl-type(B1) structure. Experiments show that with the application of pressure these compounds transform to the CsCl-type (B2) structure. ThSb and ThAs are found to exhibit B1-B2 transition in the pressure range between 9-12 GPa and 1826 GPa respectively. In this work, we present the electronic and high-pressure behaviour of ThAs and ThSb performed using the tight-binding linear muffin-tin orbital method. The total energies within the atomic sphere approximation were calculated as a function of volume for both the B1 and B2 structures. The total energy calculations reveal that both ThSb and ThAs are stable in the B1 structure at ambient conditions and undergo structural transition to the B2 structure at pressures 78 and 240 kbar respectively, which are in good agreement with the experimental values. The calculated values of equilibrium lattice parameter and the transition pressure are found to be in good agreement with the experimental results. (author)

  11. Applied statistical thermodynamics

    CERN Document Server

    Lucas, Klaus

    1991-01-01

    The book guides the reader from the foundations of statisti- cal thermodynamics including the theory of intermolecular forces to modern computer-aided applications in chemical en- gineering and physical chemistry. The approach is new. The foundations of quantum and statistical mechanics are presen- ted in a simple way and their applications to the prediction of fluid phase behavior of real systems are demonstrated. A particular effort is made to introduce the reader to expli- cit formulations of intermolecular interaction models and to show how these models influence the properties of fluid sy- stems. The established methods of statistical mechanics - computer simulation, perturbation theory, and numerical in- tegration - are discussed in a style appropriate for newcom- ers and are extensively applied. Numerous worked examples illustrate how practical calculations should be carried out.

  12. Heat and thermodynamics

    CERN Document Server

    Saxena, A K

    2014-01-01

    Heat and thermodynamics aims to serve as a textbook for Physics, Chemistry and Engineering students. The book covers basic ideas of Heat and Thermodynamics, Kinetic Theory and Transport Phenomena, Real Gases, Liquafaction and Production and Measurement of very Low Temperatures, The First Law of Thermodynamics, The Second and Third Laws of Thermodynamics and Heat Engines and Black Body Radiation. KEY FEATURES Emphasis on concepts Contains 145 illustrations (drawings), 9 Tables and 48 solved examples At the end of chapter exercises and objective questions

  13. 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

  14. Advanced classical thermodynamics

    International Nuclear Information System (INIS)

    Emanuel, G.

    1987-01-01

    The theoretical and mathematical foundations of thermodynamics are presented in an advanced text intended for graduate engineering students. Chapters are devoted to definitions and postulates, the fundamental equation, equilibrium, the application of Jacobian theory to thermodynamics, the Maxwell equations, stability, the theory of real gases, critical-point theory, and chemical thermodynamics. Diagrams, graphs, tables, and sample problems are provided. 38 references

  15. Phase stability predictions of Cr1−x, Mx)2(Al1−y, Ay)(C1−z, Xz) (M = Ti, Hf, Zr; A = Si, X = B)

    International Nuclear Information System (INIS)

    Shang, Lin; Music, Denis; Baben, Moritz to; Schneider, Jochen M

    2014-01-01

    The phase stability of (Cr 1−x , M x ) 2 (Al 1−y , A y )(C 1−z , X z ) (M = Ti, Hf, Zr; A = Si, X = B, space group P6 3 /mmc, prototype Cr 2 AlC) was studied using ab initio calculations. Based on the energy of mixing data as well as the density of states (DOS) analysis, (Cr 1−x , Zr x ) 2 AlC and (Cr 1−x , Hf x ) 2 AlC are predicted to be unstable, whereas (Cr 1−x , Ti x ) 2 AlC, Cr 2 (Al 1−y , Si y )C and Cr 2 Al(C 1−z , B z ) are predicted to be stable or metastable. The density of states analysis reveals that small differences in the position of the Fermi level alters the phase stability: (Cr 1−x , Zr x ) 2 AlC and (Cr 1−x , Hf x ) 2 AlC are predicted to be unstable or metastable as the Fermi level lies at a peak position. While the Cr dominated DOS for (Cr 1−x , Ti x ) 2 AlC plateaus at the Fermi level indicating stability. Implications of these results for the vapour phase condensation of self-healing Cr 2 AlC based materials are discussed. (paper)

  16. Chiral thermodynamics of nuclear matter

    Energy Technology Data Exchange (ETDEWEB)

    Fiorilla, Salvatore

    2012-10-23

    The equation of state of nuclear matter is calculated at finite temperature in the framework of in-medium chiral perturbation theory up to three-loop order. The dependence of its thermodynamic properties on the isospin-asymmetry is investigated. The chiral quark condensate is evaluated for symmetric nuclear matter. Its behaviour as a function of density and temperature sets important nuclear physics constraints for the QCD phase diagram.

  17. THERMODYNAMIC MODEL OF GAS HYDRATES

    OpenAIRE

    Недоступ, В. И.; Недоступ, О. В.

    2015-01-01

    The interest to gas hydrates grows last years. Therefore working out of reliable settlement-theoretical methods of definition of their properties is necessary. The thermodynamic model of gas hydrates in which the central place occupies a behaviour of guest molecule in cell is described. The equations of interaction of molecule hydrate formative gas with cell are received, and also an enthalpy and energy of output of molecule from a cell are determined. The equation for calculation of thermody...

  18. Chiral thermodynamics of nuclear matter

    International Nuclear Information System (INIS)

    Fiorilla, Salvatore

    2012-01-01

    The equation of state of nuclear matter is calculated at finite temperature in the framework of in-medium chiral perturbation theory up to three-loop order. The dependence of its thermodynamic properties on the isospin-asymmetry is investigated. The chiral quark condensate is evaluated for symmetric nuclear matter. Its behaviour as a function of density and temperature sets important nuclear physics constraints for the QCD phase diagram.

  19. A study in cosmology and causal thermodynamics

    International Nuclear Information System (INIS)

    Oliveira, H.P. de.

    1986-01-01

    The especial relativity of thermodynamic theories for reversible and irreversible processes in continuous medium is studied. The formalism referring to equilibrium and non-equilibrium configurations, and theories which includes the presence of gravitational fields are discussed. The nebular model in contraction with dissipative processes identified by heat flux and volumetric viscosity is thermodymically analysed. This model is presented by a plane conformal metric. The temperature, pressure, entropy and entropy production within thermodynamic formalism which adopts the hypothesis of local equilibrium, is calculated. The same analysis is carried out considering a causal thermodynamics, which establishes a local entropy of non-equilibrium. Possible homogeneous and isotropic cosmological models, considering the new phenomenological equation for volumetric viscosity deriving from cause thermodynamics are investigated. The found out models have plane spatial section (K=0) and some ones do not have singularities. The energy conditions are verified and the entropy production for physically reasobable models are calculated. (M.C.K.) [pt

  20. The impact of quark masses on pQCD thermodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Graf, Thorben; Schaffner-Bielich, Juergen [Goethe University, Institute for Theoretical Physics, Frankfurt am Main (Germany); Fraga, Eduardo S. [Universidade Federal do Rio de Janeiro, Instituto de Fisica, Rio de Janeiro (Brazil)

    2016-07-15

    We present results for several thermodynamic quantities within the next-to-leading order calculation of the thermodynamic potential in perturbative QCD at finite temperature and chemical potential including non-vanishing quark masses. These results are compared to lattice data and to higher-order optimized perturbative calculations to investigate the trend brought about by mass corrections. (orig.)

  1. Introduction to applied thermodynamics

    CERN Document Server

    Helsdon, R M; Walker, G E

    1965-01-01

    Introduction to Applied Thermodynamics is an introductory text on applied thermodynamics and covers topics ranging from energy and temperature to reversibility and entropy, the first and second laws of thermodynamics, and the properties of ideal gases. Standard air cycles and the thermodynamic properties of pure substances are also discussed, together with gas compressors, combustion, and psychrometry. This volume is comprised of 16 chapters and begins with an overview of the concept of energy as well as the macroscopic and molecular approaches to thermodynamics. The following chapters focus o

  2. Twenty lectures on thermodynamics

    CERN Document Server

    Buchdahl, H A

    2013-01-01

    Twenty Lectures on Thermodynamics is a course of lectures, parts of which the author has given various times over the last few years. The book gives the readers a bird's eye view of phenomenological and statistical thermodynamics. The book covers many areas in thermodynamics such as states and transition; adiabatic isolation; irreversibility; the first, second, third and Zeroth laws of thermodynamics; entropy and entropy law; the idea of the application of thermodynamics; pseudo-states; the quantum-static al canonical and grand canonical ensembles; and semi-classical gaseous systems. The text

  3. Phase stability and oxygen diffusion in RBa2Cu3O6+x (R=Y, Nd)

    International Nuclear Information System (INIS)

    Mozhaev, A.P.; Mazo, G.N.; Galkin, A.A.; Khromova, N.V.

    1996-01-01

    Phase stability boundaries of RBa 2 Cu 3 O 6 + x (R=Y, Nd) compounds for oxygen partial pressure wide range were determined by means of Coulomb titration. Phase decomposition is shown to occur without formation of liquid phase. Principial differences in the chemical composition of decomposition product of Y- and Nd-containing phases were detected. Dependences of oxygen non-stoichiometry of the compounds on temperature were determined. Fragments of P o 2 -T-x-diagrams were plotted. Oxygen diffusion coefficients within wide range of temperatures and partial pressures of oxygen were determined. Dependence of diffusion parameters on oxygen non-stoichiometry and P o 2 was determined. Oxygen diffusion was determined to occur more rapidly in orthorhombic phase than in tetragonal one. Diffusion coefficients were shown to increase at transition from Y-to Nd-containing phase. 13 refs., 6 figs., 2 tabs

  4. Magnetic properties and phase stability of half-metal-type Co2Cr1-xFexGa alloys

    International Nuclear Information System (INIS)

    Kobayashi, K.; Umetsu, R.Y.; Fujita, A.; Oikawa, K.; Kainuma, R.; Fukamichi, K.; Ishida, K.

    2005-01-01

    The magnetic properties and phase stability of half-metal-type Co 2 Cr 1-x Fe x Ga alloys were investigated by differential scanning calorimetry (DSC), in a superconducting quantum interference device (SQUID) magnetometer and in a vibrating sample magnetometer (VSM), and by transmission electron microscopy (TEM). It was found that the L2 1 -type single-phase is obtainable for the entire concentration of x and that the value of the saturation magnetic moment M s at 4.2K in the lower composition range of x is in agreement with the generalized Slater-Pauling line, while it is rather larger than the generalized Slater-Pauling line above x=0.6. The Curie temperature T c monotonically increases, whereas the transition temperature from the L2 1 - to B2-type phase T t B2/L2 1 is almost constant at 1082+/-13K with increasing x

  5. Rational extended thermodynamics

    CERN Document Server

    Müller, Ingo

    1998-01-01

    Ordinary thermodynamics provides reliable results when the thermodynamic fields are smooth, in the sense that there are no steep gradients and no rapid changes. In fluids and gases this is the domain of the equations of Navier-Stokes and Fourier. Extended thermodynamics becomes relevant for rapidly varying and strongly inhomogeneous processes. Thus the propagation of high­ frequency waves, and the shape of shock waves, and the regression of small-scale fluctuation are governed by extended thermodynamics. The field equations of ordinary thermodynamics are parabolic while extended thermodynamics is governed by hyperbolic systems. The main ingredients of extended thermodynamics are • field equations of balance type, • constitutive quantities depending on the present local state and • entropy as a concave function of the state variables. This set of assumptions leads to first order quasi-linear symmetric hyperbolic systems of field equations; it guarantees the well-posedness of initial value problems and f...

  6. Thermodynamic theory of black holes

    Energy Technology Data Exchange (ETDEWEB)

    Davies, P C.W. [King' s Coll., London (UK). Dept. of Mathematics

    1977-04-21

    The thermodynamic theory underlying black hole processes is developed in detail and applied to model systems. It is found that Kerr-Newman black holes undergo a phase transition at a = 0.68M or Q = 0.86M, where the heat capacity has an infinite discontinuity. Above the transition values the specific heat is positive, permitting isothermal equilibrium with a surrounding heat bath. Simple processes and stability criteria for various black hole situations are investigated. The limits for entropically favoured black hole formation are found. The Nernst conditions for the third law of thermodynamics are not satisfied fully for black holes. There is no obvious thermodynamic reason why a black hole may not be cooled down below absolute zero and converted into a naked singularity. Quantum energy-momentum tensor calculations for uncharged black holes are extended to the Reissner-Nordstrom case, and found to be fully consistent with the thermodynamic picture for Q < M. For Q < M the model predicts that 'naked' collapse also produces radiation, with such intensity that the collapsing matter is entirely evaporated away before a naked singularity can form.

  7. Thermodynamic and kinetic properties of intrinsic defects and Mg transmutants in 3C–SiC determined by density functional theory

    International Nuclear Information System (INIS)

    Hu, Shenyang; Setyawan, Wahyu; Van Ginhoven, Renee M.; Jiang, Weilin; Henager, Charles H.; Kurtz, Richard J.

    2014-01-01

    Density functional theory (DFT) is used to calculate the thermodynamic and kinetic properties of transmutant Mg in 3C–SiC due to high-energy neutron irradiation associated with the fusion nuclear environment. The formation and binding energies of intrinsic defects, Mg-related defects, and clusters in 3C–SiC are systematically calculated. The minimum energy paths and activation energies during point defect migration and small cluster evolution are studied using a generalized solid-state nudged elastic band (G-SSNEB) method with DFT energy calculations. Stable defect structures and possible defect migration mechanisms are identified. The evolution of binding energies during Mg 2 Si formation demonstrates that the formation of Mg 2 Si needs to overcome a critical nucleus size and nucleation barrier. It is found that C vacancies promote the formation of the Mg 2 Si nucleus, and formation of which results in a compressive stress field around the nucleus. These data are important inputs in meso- and macro-scale modeling and experiments to understand and predict the impact of Mg on phase stability, microstructure evolution, and performance of SiC and SiC-based materials during long-term neutron exposures

  8. A search for the ground state structure and the phase stability of tantalum pentoxide

    International Nuclear Information System (INIS)

    Pérez-Walton, S; Valencia-Balvín, C; Padilha, A C M; Dalpian, G M; Osorio-Guillén, J M

    2016-01-01

    Tantalum pentoxide (Ta 2 O 5 ) is a wide-gap semiconductor that presents good catalytic and dielectric properties, conferring to this compound promising prospective use in a variety of technological applications. However, there is a lack of understanding regarding the relations among its crystalline phases, as some of them are not even completely characterized and there is currently no agreement about which models better explain the crystallographic data. Additionally, its phase diagram is unknown. In this work we performed first-principles density functional theory calculations to study the structural properties of the different phases and models of Ta 2 O 5 , the equation of state and the zone-centered vibrational frequencies. From our results, we conclude that the phases that are built up from only distorted octahedra instead of combinations with pentagonal and/or hexagonal bipyramids are energetically more favorable and dynamically stable. More importantly, this study establishes that, given the pressure range considered, the B-phase is the most favorable structure and there is no a crystallographic phase transition to another phase at high-pressure. Additionally, for the equilibrium volume of the B-phase and the λ-model, the description of the electronic structure and optical properties were performed using semi-local and hybrid functionals. (paper)

  9. Biochemical thermodynamics: applications of Mathematica.

    Science.gov (United States)

    Alberty, Robert A

    2006-01-01

    The most efficient way to store thermodynamic data on enzyme-catalyzed reactions is to use matrices of species properties. Since equilibrium in enzyme-catalyzed reactions is reached at specified pH values, the thermodynamics of the reactions is discussed in terms of transformed thermodynamic properties. These transformed thermodynamic properties are complicated functions of temperature, pH, and ionic strength that can be calculated from the matrices of species values. The most important of these transformed thermodynamic properties is the standard transformed Gibbs energy of formation of a reactant (sum of species). It is the most important because when this function of temperature, pH, and ionic strength is known, all the other standard transformed properties can be calculated by taking partial derivatives. The species database in this package contains data matrices for 199 reactants. For 94 of these reactants, standard enthalpies of formation of species are known, and so standard transformed Gibbs energies, standard transformed enthalpies, standard transformed entropies, and average numbers of hydrogen atoms can be calculated as functions of temperature, pH, and ionic strength. For reactions between these 94 reactants, the changes in these properties can be calculated over a range of temperatures, pHs, and ionic strengths, and so can apparent equilibrium constants. For the other 105 reactants, only standard transformed Gibbs energies of formation and average numbers of hydrogen atoms at 298.15 K can be calculated. The loading of this package provides functions of pH and ionic strength at 298.15 K for standard transformed Gibbs energies of formation and average numbers of hydrogen atoms for 199 reactants. It also provides functions of temperature, pH, and ionic strength for the standard transformed Gibbs energies of formation, standard transformed enthalpies of formation, standard transformed entropies of formation, and average numbers of hydrogen atoms for 94

  10. Structures, phase stabilities, and electrical potentials of Li-Si battery anode materials

    KAUST Repository

    Tipton, William W.

    2013-05-28

    The Li-Si materials system holds promise for use as an anode in Li-ion battery applications. For this system, we determine the charge capacity, voltage profiles, and energy storage density solely by ab initio methods without any experimental input. We determine the energetics of the stable and metastable Li-Si phases likely to form during the charging and discharging of a battery. Ab initio molecular dynamics simulations are used to model the structure of amorphous Li-Si as a function of composition, and a genetic algorithm coupled to density-functional theory searches the Li-Si binary phase diagram for small-cell, metastable crystal structures. Calculations of the phonon densities of states using density-functional perturbation theory for selected structures determine the importance of vibrational, including zero-point, contributions to the free energies. The energetics and local structural motifs of these metastable Li-Si phases closely resemble those of the amorphous phases, making these small unit cell crystal phases good approximants of the amorphous phase for use in further studies. The charge capacity is estimated, and the electrical potential profiles and the energy density of Li-Si anodes are predicted. We find, in good agreement with experimental measurements, that the formation of amorphous Li-Si only slightly increases the anode potential. Additionally, the genetic algorithm identifies a previously unreported member of the Li-Si binary phase diagram with composition Li5Si2 which is stable at 0 K with respect to previously known phases. We discuss its relationship to the partially occupied Li7Si3 phase. © 2013 American Physical Society.

  11. Systematics of Structural, Phase Stability, and Cohesive Properties of η'-Cu6(Sn,In)5 Compounds Occurring in In-Sn/Cu Solder Joints

    Science.gov (United States)

    Ramos, S. B.; González Lemus, N. V.; Deluque Toro, C. E.; Cabeza, G. F.; Fernández Guillermet, A.

    2017-07-01

    Motivated by the high solubility of In in ( mC44) η'-Cu6Sn5 compound as well as the occurrence of an In-doped η'-intermetallic in the microstructure of Cu/In-Sn/Cu solder joints, a theoretical study has been carried out to investigate the various physical effects of incorporating In at Sn Wyckoff sites of the binary η'-phase. Systematic ab initio calculations using the projected augmented wave method and Vienna Ab initio Simulation Package were used to determine the composition dependence of the structural and cohesive properties of η'-Cu6(Sn,In)5 compounds, compared with those expected from the binary end-member compounds Cu6Sn5 and Cu6In5. The molar volume shows significant deviations from Vegard's law. The predicted composition dependence of the cohesive properties is discussed using two complementary approaches, viz. a valence-electron density approach as well as a bond-number approach, both accounting for the roughly linear dependence of the cohesive energy on the In content. A microscopic interpretation for this general trend is given in terms of the key contributions to chemical bonding in this class of compounds, namely Cu d-electron overlap and hybridization of Cu d-states with In and Sn p-electron states. Moreover, a crystallographic site approach is developed to accurately establish the phase-stabilizing effect of incorporating In at specific Wyckoff positions of the ( mC44) η'-Cu6Sn5 structure.

  12. Thermodynamic equilibrium-air correlations for flowfield applications

    Science.gov (United States)

    Zoby, E. V.; Moss, J. N.

    1981-01-01

    Equilibrium-air thermodynamic correlations have been developed for flowfield calculation procedures. A comparison between the postshock results computed by the correlation equations and detailed chemistry calculations is very good. The thermodynamic correlations are incorporated in an approximate inviscid flowfield code with a convective heating capability for the purpose of defining the thermodynamic environment through the shock layer. Comparisons of heating rates computed by the approximate code and a viscous-shock-layer method are good. In addition to presenting the thermodynamic correlations, the impact of several viscosity models on the convective heat transfer is demonstrated.

  13. Nonstoichiometry and phase stability of Al and Cr substituted Mg ferrite nanoparticles synthesized by citrate method

    Energy Technology Data Exchange (ETDEWEB)

    Ateia, Ebtesam E.; Mohamed, Amira T., E-mail: atawfik@sci.cu.edu.eg

    2017-03-15

    The spinel ferrite Mg{sub 0.7}Cr{sub 0.3}Fe{sub 2}O{sub 4}, and Mg{sub 0.7}Al{sub 0.3}Fe{sub 2}O{sub 4} were prepared by the citrate technique. All samples were characterized by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), High Resolution Transmission Electron Micrographs (HRTEM), Energy Dispersive X ray Spectroscopy (EDAX) and Atomic Force Microscope (AFM). XRD confirmed the formation of cubic spinel structure of the investigated samples. The average crystallite sizes were found to be between 24.7 and 27.5 nm for Al{sup 3+} and Mg{sup 2+} respectively. The substitution of Cr{sup 3+}/Al{sup 3+} in place of Mg{sup 2+} ion initiates a crystalline anisotropy due to large size mismatch between Cr /Al and Mg{sup 2+}, which creates strain inside the crystal volume. According to VSM results, by adding Al{sup 3+} or Cr{sup 3+} ions at the expense of Mg{sup 2+}, the saturation magnetization increased. The narrow hysteresis loop of the samples indicates that the amount of dissipated energy is small, which is desirable for soft magnetic applications. Magnetic dynamics of the samples were studied by measuring magnetic susceptibility versus temperature at different magnetic fields. The band gap energy, which was calculated from near infrared (NIR) and visible (VIS) reflectance spectra using the Kubelka-Munk function, decreases with increasing the particle size. Furthermore, the band gaps were quite narrow (1.5–1.7 eV), hence the investigated samples could act as visible light driven photo catalysts. To sum up the addition of trivalent Al{sup 3+}, and Cr{sup 3+} ions enhanced the optical, magnetic and structure properties of the samples. Mg{sub 0.7} Cr{sub 0.3}Fe{sub 2}O{sub 4} sample will be a better candidate for the optical applications and will also be a guaranteeing hopeful for technological applications. - Highlights: • Nanoparticles of (Mg{sub 0.7} Al{sub 0.3} Fe{sub 2}O{sub 4}) ferrite are the potential candidates for various

  14. The effect of boron concentration on the structure and elastic properties of Ru-Ir alloys: first-principles calculations

    Science.gov (United States)

    Li, Xiaolong; Zhou, Zhaobo; Hu, Riming; Zhou, Xiaolong; Yu, Jie; Liu, Manmen

    2018-04-01

    The Phase stability, electronic structure, elastic properties and hardness of Ru-Ir alloys with different B concentration were investigated by first principles calculations. The calculated formation enthaplies and cohesive energies show that these compounds are all thermodynamically stable. Information on electronic structure indicates that they possess metallic characteristic and Ru-Ir-B alloys were composed of the Ru-B and Ir-B covalent bond. The elastic properties were calculated, which included bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio and hardness. The calculated results reveal that the plastic of Ru-Ir-B alloys increase with the increase of the content of B atoms, but the hardness of Ru-Ir-B alloys have no substantial progress with the increase of the content of B atoms. However, it is interesting that the hardness of the Ru-Ir-B compound was improved obviously as the B content was higher than 18 atoms because of a phase structure transition.

  15. An introduction to equilibrium thermodynamics

    CERN Document Server

    Morrill, Bernard; Hartnett, James P; Hughes, William F

    1973-01-01

    An Introduction to Equilibrium Thermodynamics discusses classical thermodynamics and irreversible thermodynamics. It introduces the laws of thermodynamics and the connection between statistical concepts and observable macroscopic properties of a thermodynamic system. Chapter 1 discusses the first law of thermodynamics while Chapters 2 through 4 deal with statistical concepts. The succeeding chapters describe the link between entropy and the reversible heat process concept of entropy; the second law of thermodynamics; Legendre transformations and Jacobian algebra. Finally, Chapter 10 provides a

  16. 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.

  17. Thermodynamics of Bioreactions.

    Science.gov (United States)

    Held, Christoph; Sadowski, Gabriele

    2016-06-07

    Thermodynamic principles have been applied to enzyme-catalyzed reactions since the beginning of the 1930s in an attempt to understand metabolic pathways. Currently, thermodynamics is also applied to the design and analysis of biotechnological processes. The key thermodynamic quantity is the Gibbs energy of reaction, which must be negative for a reaction to occur spontaneously. However, the application of thermodynamic feasibility studies sometimes yields positive Gibbs energies of reaction even for reactions that are known to occur spontaneously, such as glycolysis. This article reviews the application of thermodynamics in enzyme-catalyzed reactions. It summarizes the basic thermodynamic relationships used for describing the Gibbs energy of reaction and also refers to the nonuniform application of these relationships in the literature. The review summarizes state-of-the-art approaches that describe the influence of temperature, pH, electrolytes, solvents, and concentrations of reacting agents on the Gibbs energy of reaction and, therefore, on the feasibility and yield of biological reactions.

  18. 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.)

  19. 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.

  20. Thermodynamically efficient solar concentrators

    Science.gov (United States)

    Winston, Roland

    2012-10-01

    Non-imaging Optics is the theory of thermodynamically efficient optics and as such depends more on thermodynamics than on optics. Hence in this paper a condition for the "best" design is proposed based on purely thermodynamic arguments, which we believe has profound consequences for design of thermal and even photovoltaic systems. This new way of looking at the problem of efficient concentration depends on probabilities, the ingredients of entropy and information theory while "optics" in the conventional sense recedes into the background.

  1. Black Holes and Thermodynamics

    OpenAIRE

    Wald, Robert M.

    1997-01-01

    We review the remarkable relationship between the laws of black hole mechanics and the ordinary laws of thermodynamics. It is emphasized that - in analogy with the laws of thermodynamics - the validity the laws of black hole mechanics does not appear to depend upon the details of the underlying dynamical theory (i.e., upon the particular field equations of general relativity). It also is emphasized that a number of unresolved issues arise in ``ordinary thermodynamics'' in the context of gener...

  2. Thermodynamics of Dipolar Chain Systems

    International Nuclear Information System (INIS)

    Armstrong, J.R.; Zinner, N.T.; Fedorov, D.V.; Jensen, A.S.

    2013-01-01

    The thermodynamics of a quantum system of layers containing perpendicularly oriented dipolar molecules is studied within an oscillator approximation for both bosonic and fermionic species. The system is assumed to be built from chains with one molecule in each layer. We consider the effects of the intralayer repulsion and quantum statistical requirements in systems with more than one chain. Specifically, we consider the case of two chains and solve the problem analytically within the harmonic Hamiltonian approach which is accurate for large dipole moments. The case of three chains is calculated numerically. Our findings indicate that thermodynamic observables, such as the heat capacity, can be used to probe the signatures of the intralayer interaction between chains. This should be relevant for near future experiments on polar molecules with strong dipole moments. (author)

  3. Methods of thermodynamics

    CERN Document Server

    Reiss, Howard

    1997-01-01

    Since there is no shortage of excellent general books on elementary thermodynamics, this book takes a different approach, focusing attention on the problem areas of understanding of concept and especially on the overwhelming but usually hidden role of ""constraints"" in thermodynamics, as well as on the lucid exposition of the significance, construction, and use (in the case of arbitrary systems) of the thermodynamic potential. It will be especially useful as an auxiliary text to be used along with any standard treatment.Unlike some texts, Methods of Thermodynamics does not use statistical m

  4. 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

  5. Phase Stability and Electronic Structure of Prospective Sb-Based Mixed Sulfide and Iodide 3D Perovskite (CH3NH3)SbSI2.

    Science.gov (United States)

    Li, Tianyang; Wang, Xiaoming; Yan, Yanfa; Mitzi, David B

    2018-06-29

    Lead-free antimony-based mixed sulfide and iodide perovskite phases have recently been reported to be synthesized experimentally and to exhibit reasonable photovoltaic performance. Through a combination of experimental validation and computational analysis, we show no evidence of the formation of the mixed sulfide and iodide perovskite phase, MASbSI 2 (MA = CH 3 NH 3 + ), and instead that the main products are a mixture of the binary and ternary compounds (Sb 2 S 3 and MA 3 Sb 2 I 9 ). Density functional theory calculations also indicate that such a mixed sulfide and iodide perovskite phase should be thermodynamically less stable compared with binary/ternary anion-segregated secondary phases and less likely to be synthesized under equilibrium conditions. Additionally, band structure calculations show that this mixed sulfide and iodide phase, if possible to synthesize (e.g., under nonequilibrium conditions), should have a suitable direct band gap for photovoltaic application.

  6. Thermodynamic properties of α-uranium

    International Nuclear Information System (INIS)

    Ren, Zhiyong; Wu, Jun; Ma, Rong; Hu, Guichao; Luo, Chao

    2016-01-01

    The lattice constants and equilibrium atomic volume of α-uranium were calculated by Density Functional Theory (DFT). The first principles calculation results of the lattice for α-uranium are in agreement with the experimental results well. The thermodynamic properties of α-uranium from 0 to 900 K and 0–100 GPa were calculated with the quasi-harmonic Debye model. Volume, bulk modulus, entropy, Debye temperature, thermal expansion coefficient and the heat capacity of α-uranium were calculated. The calculated results show that the bulk modulus and Debye temperature increase with the increasing pressure at a given temperature while decreasing with the increasing temperature at a given pressure. Volume, entropy, thermal expansion coefficient and the heat capacity decrease with the increasing pressure while increasing with the increasing temperature. The theoretical results of entropy, Debye temperature, thermal expansion coefficient and the heat capacity show good agreement with the general trends of the experimental values. The constant-volume heat capacity shows typical Debye T"3 power-law behavior at low temperature limit and approaches to the classical asymptotic Dulong-Petit limit at high temperature limit. - Highlights: • Thermodynamic properties of α-U were predicted systematically with quasi-harmonic Debye model. • Summarizations of the corresponding experimental and theoretical results have been made for the EOS and other thermodynamic parameters. • The calculated thermodynamic properties show good agreement with the experimental results in general trends.

  7. Thermodynamic properties of α-uranium

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Zhiyong; Wu, Jun; Ma, Rong; Hu, Guichao; Luo, Chao, E-mail: luochaoboss@sohu.com

    2016-11-15

    The lattice constants and equilibrium atomic volume of α-uranium were calculated by Density Functional Theory (DFT). The first principles calculation results of the lattice for α-uranium are in agreement with the experimental results well. The thermodynamic properties of α-uranium from 0 to 900 K and 0–100 GPa were calculated with the quasi-harmonic Debye model. Volume, bulk modulus, entropy, Debye temperature, thermal expansion coefficient and the heat capacity of α-uranium were calculated. The calculated results show that the bulk modulus and Debye temperature increase with the increasing pressure at a given temperature while decreasing with the increasing temperature at a given pressure. Volume, entropy, thermal expansion coefficient and the heat capacity decrease with the increasing pressure while increasing with the increasing temperature. The theoretical results of entropy, Debye temperature, thermal expansion coefficient and the heat capacity show good agreement with the general trends of the experimental values. The constant-volume heat capacity shows typical Debye T{sup 3} power-law behavior at low temperature limit and approaches to the classical asymptotic Dulong-Petit limit at high temperature limit. - Highlights: • Thermodynamic properties of α-U were predicted systematically with quasi-harmonic Debye model. • Summarizations of the corresponding experimental and theoretical results have been made for the EOS and other thermodynamic parameters. • The calculated thermodynamic properties show good agreement with the experimental results in general trends.

  8. Thermodynamic and Quantum Thermodynamic Analyses of Brownian Movement

    OpenAIRE

    Gyftopoulos, Elias P.

    2006-01-01

    Thermodynamic and quantum thermodynamic analyses of Brownian movement of a solvent and a colloid passing through neutral thermodynamic equilibrium states only. It is shown that Brownian motors and E. coli do not represent Brownian movement.

  9. Thermodynamics of nuclear materials

    International Nuclear Information System (INIS)

    1979-01-01

    Full text: The science of chemical thermodynamics has substantially contributed to the understanding of the many problems encountered in nuclear and reactor technology. These problems include reaction of materials with their surroundings and chemical and physical changes of fuels. Modern reactor technology, by its very nature, has offered new fields of investigations for the scientists and engineers concerned with the design of nuclear fuel elements. Moreover, thermodynamics has been vital in predicting the behaviour of new materials for fission as well as fusion reactors. In this regard, the Symposium was organized to provide a mechanism for review and discussion of recent thermodynamic investigations of nuclear materials. The Symposium was held in the Juelich Nuclear Research Centre, at the invitation of the Government of the Federal Republic of Germany. The International Atomic Energy Agency has given much attention to the thermodynamics of nuclear materials, as is evidenced by its sponsorship of four international symposia in 1962, 1965, 1967, and 1974. The first three meetings were primarily concerned with the fundamental thermodynamics of nuclear materials; as with the 1974 meeting, this last Symposium was primarily aimed at the thermodynamic behaviour of nuclear materials in actual practice, i.e., applied thermodynamics. Many advances have been made since the 1974 meeting, both in fundamental and applied thermodynamics of nuclear materials, and this meeting provided opportunities for an exchange of new information on this topic. The Symposium dealt in part with the thermodynamic analysis of nuclear materials under conditions of high temperatures and a severe radiation environment. Several sessions were devoted to the thermodynamic studies of nuclear fuels and fission and fusion reactor materials under adverse conditions. These papers and ensuing discussions provided a better understanding of the chemical behaviour of fuels and materials under these

  10. Systemic analysis of thermodynamic properties of lanthanide halides

    International Nuclear Information System (INIS)

    Mirsaidov, U.; Badalov, A.; Marufi, V.K.

    1992-01-01

    System analysis of thermodynamic characteristics of lanthanide halides was carried out. A method making allowances for the influence of spin and orbital moments of momentum of the main states of lanthanide trivalent ions in their natural series was employed. Unknown in literature thermodynamic values were calculated and corrected for certain compounds. The character of lanthanide halide thermodynamic parameter change depending on ordinal number of the metals was ascertained. Pronouncement of tetrad-effect in series of compounds considered was pointed out

  11. In-situ anatase phase stabilization of titania photocatalyst by sintering in presence of Zr4+ organic salts

    Science.gov (United States)

    Strini, Alberto; Sanson, Alessandra; Mercadelli, Elisa; Bendoni, Riccardo; Marelli, Marcello; Dal Santo, Vladimiro; Schiavi, Luca

    2015-08-01

    The direct in-situ stabilization of an anatase-based nanocrystalline photocatalyst (Degussa P25) was obtained by sintering the catalyst powder in presence of Zr4+ organic salts. This approach allows the doping of an already-formed nanocrystalline photocatalyst instead of introducing the dopant in the crystal lattice during the catalyst synthesis. The procedure was demonstrated by the production of thick ceramic layers using the screen printing technique. This new method allows to easily stabilize the anatase phase 200 °C higher than the undoped P25 maintaining the same photocatalytic activity. The process was studied using specifically formulated screen-printing inks added with Zr4+ organic salt at 1% and 2% Zr/Ti molar ratio. The anatase phase stability was investigated in the 500-900 °C temperature range analysing the resulting catalysts with XRD, TEM and (S)TEM-EDS. The catalytic activity of the screen-printed layers was assessed by measuring the degradation of toluene in air at ambient concentration (500 nmol m-3) and low UV-A irradiance (180 μW cm-2). The described in-situ stabilization method could be potentially applied to any deposition process involving already formed anatase photocatalyst, allowing higher sintering temperature and then an improved mechanical stability of the active layers without photocatalytic activity degradation.

  12. Size-Controlled AgI/Ag Heteronanowires in Highly Ordered Alumina Membranes: Superionic Phase Stabilization and Conductivity.

    Science.gov (United States)

    Zhang, Hemin; Tsuchiya, Takashi; Liang, Changhao; Terabe, Kazuya

    2015-08-12

    Nanoscaled ionic conductors are crucial for future nanodevices. A well-known ionic conductor, AgI, exhibited conductivity greater than 1 Ω(-1) cm(-1) in α-phase and transformed into poorly conducting β-/γ-phase below 147 °C, thereby limiting applications. Here, we report that transition temperatures both from the β-/γ- to α-phase (Tc↑) and the α- to β-/γ-phase (Tc↓) are tuned by AgI/Ag heteronanowires embedded in anodic aluminum oxide (AAO) membranes with 10-30 nm pores. Tc↑ and Tc↓ shift to correspondingly higher and lower temperature as pore size decreases, generating a progressively enlarged thermal hysteresis. Tc↑ and Tc↓ specifically achieve 185 and 52 °C in 10 nm pores, and the final survived conductivity reaches ∼8.3 × 10(-3) Ω(-1) cm(-1) at room temperature. Moreover, the low-temperature stabilizing α-phase (down to 21 °C, the lowest in state of the art temperatures) is reproducible and survives further thermal cycling. The low-temperature phase stabilization and enhancement conductivity reported here suggest promising applications in silver-ion-based future nanodevices.

  13. Thermodynamics and heat power

    CERN Document Server

    Granet, Irving

    2014-01-01

    Fundamental ConceptsIntroductionThermodynamic SystemsTemperatureForce and MassElementary Kinetic Theory of GasesPressureReviewKey TermsEquations Developed in This ChapterQuestionsProblemsWork, Energy, and HeatIntroductionWorkEnergyInternal EnergyPotential EnergyKinetic EnergyHeatFlow WorkNonflow WorkReviewKey TermsEquations Developed in This ChapterQuestionsProblemsFirst Law of ThermodynamicsIntroductionFirst Law of ThermodynamicsNonflow SystemSteady-Flow SystemApplications of First Law of ThermodynamicsReviewKey TermsEquations Developed in This ChapterQuestionsProblemsThe Second Law of ThermodynamicsIntroductionReversibility-Second Law of ThermodynamicsThe Carnot CycleEntropyReviewKey TermsEquations Developed in This ChapterQuestionsProblemsProperties of Liquids and GasesIntroductionLiquids and VaporsThermodynamic Properties of SteamComputerized PropertiesThermodynamic DiagramsProcessesReviewKey TermsEquations Developed in This ChapterQuestionsProblemsThe Ideal GasIntroductionBasic ConsiderationsSpecific Hea...

  14. The thermodynamic solar energy

    International Nuclear Information System (INIS)

    Rivoire, B.

    2002-04-01

    The thermodynamic solar energy is the technic in the whole aiming to transform the solar radiation energy in high temperature heat and then in mechanical energy by a thermodynamic cycle. These technic are most often at an experimental scale. This paper describes and analyzes the research programs developed in the advanced countries, since 1980. (A.L.B.)

  15. Quasiparticles and thermodynamical consistency

    International Nuclear Information System (INIS)

    Shanenko, A.A.; Biro, T.S.; Toneev, V.D.

    2003-01-01

    A brief and simple introduction into the problem of the thermodynamical consistency is given. The thermodynamical consistency relations, which should be taken into account under constructing a quasiparticle model, are found in a general manner from the finite-temperature extension of the Hellmann-Feynman theorem. Restrictions following from these relations are illustrated by simple physical examples. (author)

  16. Thermodynamic properties of potassium chloride aqueous solutions

    Science.gov (United States)

    Zezin, Denis; Driesner, Thomas

    2017-04-01

    Potassium chloride is a ubiquitous salt in natural fluids, being the second most abundant dissolved salt in many geological aqueous solutions after sodium chloride. It is a simple solute and strong electrolyte easily dissociating in water, however the thermodynamic properties of KCl aqueous solutions were never correlated with sufficient accuracy for a wide range of physicochemical conditions. In this communication we propose a set of parameters for a Pitzer-type model which allows calculation of all necessary thermodynamic properties of KCl solution, namely excess Gibbs free energy and derived activity coefficient, apparent molar enthalpy, heat capacity and volume, as well as osmotic coefficient and activity of water in solutions. The system KCl-water is one of the best studied aqueous systems containing electrolytes. Although extensive experimental data were collected for thermodynamic properties of these solutions over the years, the accurate volumetric data became available only recently, thus making possible a complete thermodynamic formulation including a pressure dependence of excess Gibbs free energy and derived properties of the KCl-water liquids. Our proposed model is intended for calculation of major thermodynamic properties of KCl aqueous solutions at temperatures ranging from freezing point of a solution to 623 K, pressures ranging from saturated water vapor up to 150 MPa, and concentrations up to the salt saturation. This parameterized model will be further implemented in geochemical software packages and can facilitate the calculation of aqueous equilibrium for reactive transport codes.

  17. Equilibrium thermodynamics - Callen's postulational approach

    NARCIS (Netherlands)

    Jongschaap, R.J.J.; Öttinger, Hans Christian

    2001-01-01

    In order to provide the background for nonequilibrium thermodynamics, we outline the fundamentals of equilibrium thermodynamics. Equilibrium thermodynamics must not only be obtained as a special case of any acceptable nonequilibrium generalization but, through its shining example, it also elucidates

  18. Thermodynamics an engineering approach

    CERN Document Server

    Cengel, Yunus A

    2014-01-01

    Thermodynamics, An Engineering Approach, eighth edition, covers the basic principles of thermodynamics while presenting a wealth of real-world engineering examples so students get a feel for how thermodynamics is applied in engineering practice. This text helps students develop an intuitive understanding by emphasizing the physics and physical arguments. Cengel and Boles explore the various facets of thermodynamics through careful explanations of concepts and use of numerous practical examples and figures, having students develop necessary skills to bridge the gap between knowledge and the confidence to properly apply their knowledge. McGraw-Hill is proud to offer Connect with the eighth edition of Cengel/Boles, Thermodynamics, An Engineering Approach. This innovative and powerful new system helps your students learn more efficiently and gives you the ability to assign homework problems simply and easily. Problems are graded automatically, and the results are recorded immediately. Track individual stude...

  19. Universal relation for size dependent thermodynamic properties of metallic nanoparticles.

    Science.gov (United States)

    Xiong, Shiyun; Qi, Weihong; Cheng, Yajuan; Huang, Baiyun; Wang, Mingpu; Li, Yejun

    2011-06-14

    The previous model on surface free energy has been extended to calculate size dependent thermodynamic properties (i.e., melting temperature, melting enthalpy, melting entropy, evaporation temperature, Curie temperature, Debye temperature and specific heat capacity) of nanoparticles. According to the quantitative calculation of size effects on the calculated thermodynamic properties, it is found that most thermodynamic properties of nanoparticles vary linearly with 1/D as a first approximation. In other words, the size dependent thermodynamic properties P(n) have the form of P(n) = P(b)(1 -K/D), in which P(b) is the corresponding bulk value and K is the material constant. This may be regarded as a scaling law for most of the size dependent thermodynamic properties for different materials. The present predictions are consistent literature values. This journal is © the Owner Societies 2011

  20. The thermodynamic-buffer enzymes.

    Science.gov (United States)

    Stucki, J W

    1980-08-01

    Oxidative phosphorylation operates at optimal efficiency if and only if the condition of conductance matching L33/L11 = square root 1-q2 is fulfilled. In this relation L11 is the phenomenological conductance of phosphorylation, L33 the phenomenological conductance of the load, i.e. the irreversible ATP-utilizing processes in the cell, and q the degree of coupling of oxidative phosphorylation driven by respiration. Since during short time intervals L11 and q are constant whereas L33 fluctuates in the cell, oxidative phosphorylation would only rarely operate at optimal efficiency due to violation of conductance matching. This paper demonstrates that the reversible ATP-utilizing reaction catalyzed by adenylate kinase can effectively compensate deviations from conductance matching in the presence of a fluctuating L33 and hence allows oxidative phosphorylation to operate at optimal efficiency in the cell. Since the adenylate kinase reaction was found to buffer a thermodynamic potential, i.e. the phosphate potential, this finding was generalized to the concept of thermodynamic buffering. The thermodynamic buffering ability of the adenylate kinase reaction was demonstrated by experiments with incubated rat-liver mitochondria. Considerations of changes introduced in the entropy production by the adenylate kinase reaction allowed to establish the theoretical framework for thermodynamic buffering. The ability of thermodynamic buffering to compensate deviations from conductance matching in the presence of fluctuating loads was demonstrated by computer simulations. The possibility of other reversible ATP-utilizing reactions, like the ones catalyzed by creatine kinase and arginine kinase, to contribute to thermodynamic buffering is discussed. Finally, the comparison of the theoretically calculated steady-stae cytosolic adenine nucleotide concentrations with experimental data from perfused livers demonstrated that in livers from fed rats conductance matching is fulfilled on a

  1. Solubility and speciation calculation for uranium, plutonium, neptunium and thorium in natural groundwaters. Theory, thermodynamic data bases and first applications. Loeslichkeits- und Speziationsberechnungen fuer U, Pu, Np und Th in natuerlichen Grundwaessern. Theorie, thermodynamische Dateien und erste Anwendungen

    Energy Technology Data Exchange (ETDEWEB)

    Schweingruber, M

    1981-11-01

    The computer code MINEQL was adapted and extended to assess the solubility and speciation of radioactive waste nuclides in groundwaters under conditions which are expected to exist in the surroundings of planned underground repositories. By means of an additional data base including standard reaction enthalpies and heat capacities at 25 degrees C, the relevant equilibrium constants at 25 degrees C can be converted to other temperatures using Ulich's formulae. The activity coefficients for dissolved species are modelled with a temperature dependent function of the Davies' approximation type. The report is segmented in three main parts: (1) a review of the MINEQL fundamentals and a summary of the theory needed for the extensions; (2) an outline of the general programme structure and of criteria applied to the selection of thermodynamic data; (3) a discussion of the results from first model applications to evaluate the solubility and speciation of U, Pu, Np and Th in two Swiss groundwaters, based either on the approach of negligible chemical disturbance or on a solid/solution titration concept. All thermodynamic data involved in this study are collected in an appendix, together with a compilation of references.

  2. Thermodynamic properties of pressurized PH3 superconductor

    Science.gov (United States)

    Koka, S.; Rao, G. Venugopal

    2018-05-01

    The paper presents the superconducting thermodynamic functions determined for pressurized phosphorus trihydride (PH3). In particular, free energy difference ΔF, thermodynamic critical field Hc, specific heat etc. have been calculated using analytical expressions. The calculations were performed in the frame work of the strong-coupling formalism. The obtained dimensionless parameters: RΔ ≡ 2Δ(0)/kBTc, RC ≡ ΔC(Tc)/CN(Tc) and RH≡TcCN(Tc)/Hc2(0) are 4.05, 1.96 and 0.156 respectively, which significantly differ from the values arising from the BCS theory of superconductivity. The thermodynamic properties strongly depend on the depairing electron correlations and retardation effects.

  3. Some remarks about the thermodynamics of discrete finite Markov chains

    Energy Technology Data Exchange (ETDEWEB)

    Siboni, S. [Trento Univ. (Italy). Facolta` di Ingegneria, Dip. di Ingegneria dei Materiali

    1998-08-01

    The Author propose a simple way to define a Hamiltonian for aperiodic Markov chains and to apply these chains in a thermodynamical context. The basic thermodynamic functions are correspondingly calculated. A quite intriguing and nontrivial application to stochastic automata is also pointed out.

  4. Nonperturbative quark-gluon thermodynamics at finite density

    Science.gov (United States)

    Andreichikov, M. A.; Lukashov, M. S.; Simonov, Yu. A.

    2018-03-01

    Thermodynamics of the quark-gluon plasma at finite density is studied in the framework of the Field Correlator Method, where thermodynamical effects of Polyakov loops and color magnetic confinement are taken into account. Having found good agreement with numerical lattice data for zero density, we calculate pressure P(T,μ), for 0 confinement.

  5. Thermodynamic fluctuations and the monopole density of the early Universe

    International Nuclear Information System (INIS)

    Diosi, L.; Lukacs, B.

    1984-10-01

    The probability of thermodynamic fluctuations is calculated by explicitly using the Riemannian structure of the thermodynamic state space. By means of this probability distribution, a correlation volume can be defined. Identifying this volume with one domain in the GUT continuum at the symmetry breaking phase transition in the early Universe, a prediction can be obtained for the primordial monopole density. (author)

  6. Thermodynamic properties of water solvating biomolecular surfaces

    Science.gov (United States)

    Heyden, Matthias

    Changes in the potential energy and entropy of water molecules hydrating biomolecular interfaces play a significant role for biomolecular solubility and association. Free energy perturbation and thermodynamic integration methods allow calculations of free energy differences between two states from simulations. However, these methods are computationally demanding and do not provide insights into individual thermodynamic contributions, i.e. changes in the solvent energy or entropy. Here, we employ methods to spatially resolve distributions of hydration water thermodynamic properties in the vicinity of biomolecular surfaces. This allows direct insights into thermodynamic signatures of the hydration of hydrophobic and hydrophilic solvent accessible sites of proteins and small molecules and comparisons to ideal model surfaces. We correlate dynamic properties of hydration water molecules, i.e. translational and rotational mobility, to their thermodynamics. The latter can be used as a guide to extract thermodynamic information from experimental measurements of site-resolved water dynamics. Further, we study energy-entropy compensations of water at different hydration sites of biomolecular surfaces. This work is supported by the Cluster of Excellence RESOLV (EXC 1069) funded by the Deutsche Forschungsgemeinschaft.

  7. Thermodynamic DFT analysis of natural gas.

    Science.gov (United States)

    Neto, Abel F G; Huda, Muhammad N; Marques, Francisco C; Borges, Rosivaldo S; Neto, Antonio M J C

    2017-08-01

    Density functional theory was performed for thermodynamic predictions on natural gas, whose B3LYP/6-311++G(d,p), B3LYP/6-31+G(d), CBS-QB3, G3, and G4 methods were applied. Additionally, we carried out thermodynamic predictions using G3/G4 averaged. The calculations were performed for each major component of seven kinds of natural gas and to their respective air + natural gas mixtures at a thermal equilibrium between room temperature and the initial temperature of a combustion chamber during the injection stage. The following thermodynamic properties were obtained: internal energy, enthalpy, Gibbs free energy and entropy, which enabled us to investigate the thermal resistance of fuels. Also, we estimated an important parameter, namely, the specific heat ratio of each natural gas; this allowed us to compare the results with the empirical functions of these parameters, where the B3LYP/6-311++G(d,p) and G3/G4 methods showed better agreements. In addition, relevant information on the thermal and mechanic resistance of natural gases were investigated, as well as the standard thermodynamic properties for the combustion of natural gas. Thus, we show that density functional theory can be useful for predicting the thermodynamic properties of natural gas, enabling the production of more efficient compositions for the investigated fuels. Graphical abstract Investigation of the thermodynamic properties of natural gas through the canonical ensemble model and the density functional theory.

  8. Thermodynamics and economics

    International Nuclear Information System (INIS)

    Mansson, B.A.

    1990-01-01

    Economics, as the social science most concerned with the use and distribution of natural resources, must start to make use of the knowledge at hand in the natural sciences about such resources. In this, thermodynamics is an essential part. In a physicists terminology, human economic activity may be described as a dissipative system which flourishes by transforming and exchanging resources, goods and services. All this involves complex networks of flows of energy and materials. This implies that thermodynamics, the physical theory of energy and materials flows, must have implications for economics. On another level, thermodynamics has been recognized as a physical theory of value, with value concepts similar to those of economic theory. This paper discusses some general aspects of the significance of non-equilibrium thermodynamics for economics. The role of exergy, probably the most important of the physical measures of value, is elucidated. Two examples of integration of thermodynamics with economic theory are reviewed. First, a simple model of a steady-state production system is sued to illustrate the effects of thermodynamic process constraints. Second, the framework of a simple macroeconomic growth model is used to illustrate how some thermodynamic limitations may be integrated in macroeconomic theory

  9. 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...

  10. In-situ anatase phase stabilization of titania photocatalyst by sintering in presence of Zr{sup 4+} organic salts

    Energy Technology Data Exchange (ETDEWEB)

    Strini, Alberto, E-mail: alberto.strini@itc.cnr.it [Istituto per le Tecnologie della Costruzione (ITC-CNR), via Lombardia, 49, I-20098 San Giuliano Milanese (MI) (Italy); Sanson, Alessandra; Mercadelli, Elisa [Istituto di Scienza e Tecnologia dei Materiali Ceramici (ISTEC-CNR), via Granarolo, 64, I-48018 Faenza (RA) (Italy); Bendoni, Riccardo [Istituto di Scienza e Tecnologia dei Materiali Ceramici (ISTEC-CNR), via Granarolo, 64, I-48018 Faenza (RA) (Italy); Dipartimento di Scienze e Tecnologie Chimiche e Centro NAST - Università di Roma Tor Vergata, via della Ricerca Scientifica, I-00133 Roma (Italy); Marelli, Marcello; Dal Santo, Vladimiro [CNR–Istituto di Scienze e Tecnologie Molecolari, via Golgi, 19, I-20133 Milano (Italy); Schiavi, Luca [Istituto per le Tecnologie della Costruzione (ITC-CNR), via Lombardia, 49, I-20098 San Giuliano Milanese (MI) (Italy)

    2015-08-30

    Graphical abstract: - Highlights: • Existing commercial (P25) anatase was stabilized in-situ with Zr(IV) doping. • Highly active catalytic layers were obtained by screen-printing. • Increased thermal stability was demonstrated up to 200 °C without activity loss. • Enhanced activity was obtained because of the Zr(IV) doping. • Zirconium diffusion was assessed by STEM-EDS analysis. - Abstract: The direct in-situ stabilization of an anatase-based nanocrystalline photocatalyst (Degussa P25) was obtained by sintering the catalyst powder in presence of Zr{sup 4+} organic salts. This approach allows the doping of an already-formed nanocrystalline photocatalyst instead of introducing the dopant in the crystal lattice during the catalyst synthesis. The procedure was demonstrated by the production of thick ceramic layers using the screen printing technique. This new method allows to easily stabilize the anatase phase 200 °C higher than the undoped P25 maintaining the same photocatalytic activity. The process was studied using specifically formulated screen-printing inks added with Zr{sup 4+} organic salt at 1% and 2% Zr/Ti molar ratio. The anatase phase stability was investigated in the 500–900 °C temperature range analysing the resulting catalysts with XRD, TEM and (S)TEM-EDS. The catalytic activity of the screen-printed layers was assessed by measuring the degradation of toluene in air at ambient concentration (500 nmol m{sup −3}) and low UV-A irradiance (180 μW cm{sup −2}). The described in-situ stabilization method could be potentially applied to any deposition process involving already formed anatase photocatalyst, allowing higher sintering temperature and then an improved mechanical stability of the active layers without photocatalytic activity degradation.

  11. In-situ anatase phase stabilization of titania photocatalyst by sintering in presence of Zr4+ organic salts

    International Nuclear Information System (INIS)

    Strini, Alberto; Sanson, Alessandra; Mercadelli, Elisa; Bendoni, Riccardo; Marelli, Marcello; Dal Santo, Vladimiro; Schiavi, Luca

    2015-01-01

    Graphical abstract: - Highlights: • Existing commercial (P25) anatase was stabilized in-situ with Zr(IV) doping. • Highly active catalytic layers were obtained by screen-printing. • Increased thermal stability was demonstrated up to 200 °C without activity loss. • Enhanced activity was obtained because of the Zr(IV) doping. • Zirconium diffusion was assessed by STEM-EDS analysis. - Abstract: The direct in-situ stabilization of an anatase-based nanocrystalline photocatalyst (Degussa P25) was obtained by sintering the catalyst powder in presence of Zr 4+ organic salts. This approach allows the doping of an already-formed nanocrystalline photocatalyst instead of introducing the dopant in the crystal lattice during the catalyst synthesis. The procedure was demonstrated by the production of thick ceramic layers using the screen printing technique. This new method allows to easily stabilize the anatase phase 200 °C higher than the undoped P25 maintaining the same photocatalytic activity. The process was studied using specifically formulated screen-printing inks added with Zr 4+ organic salt at 1% and 2% Zr/Ti molar ratio. The anatase phase stability was investigated in the 500–900 °C temperature range analysing the resulting catalysts with XRD, TEM and (S)TEM-EDS. The catalytic activity of the screen-printed layers was assessed by measuring the degradation of toluene in air at ambient concentration (500 nmol m −3 ) and low UV-A irradiance (180 μW cm −2 ). The described in-situ stabilization method could be potentially applied to any deposition process involving already formed anatase photocatalyst, allowing higher sintering temperature and then an improved mechanical stability of the active layers without photocatalytic activity degradation

  12. Advanced thermodynamics engineering

    CERN Document Server

    Annamalai, Kalyan; Jog, Milind A

    2011-01-01

    Thermolab Excel-Based Software for Thermodynamic Properties and Flame Temperatures of Fuels IntroductionImportance, Significance and LimitationsReview of ThermodynamicsMathematical BackgroundOverview of Microscopic/NanothermodynamicsSummaryAppendix: Stokes and Gauss Theorems First Law of ThermodynamicsZeroth LawFirst Law for a Closed SystemQuasi Equilibrium (QE) and Nonquasi-equilibrium (NQE) ProcessesEnthalpy and First LawAdiabatic Reversible Process for Ideal Gas with Constant Specific HeatsFirst Law for an Open SystemApplications of First Law for an Open SystemIntegral and Differential Form

  13. Thermodynamics I essentials

    CERN Document Server

    REA, The Editors of

    2012-01-01

    REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Thermodynamics I includes review of properties and states of a pure substance, work and heat, energy and the first law of thermodynamics, entropy and the second law of thermodynamics

  14. Non-equilibrium thermodynamics

    CERN Document Server

    De Groot, Sybren Ruurds

    1984-01-01

    The study of thermodynamics is especially timely today, as its concepts are being applied to problems in biology, biochemistry, electrochemistry, and engineering. This book treats irreversible processes and phenomena - non-equilibrium thermodynamics.S. R. de Groot and P. Mazur, Professors of Theoretical Physics, present a comprehensive and insightful survey of the foundations of the field, providing the only complete discussion of the fluctuating linear theory of irreversible thermodynamics. The application covers a wide range of topics: the theory of diffusion and heat conduction, fluid dyn

  15. Modern engineering thermodynamics

    CERN Document Server

    Balmer, Robert T

    2010-01-01

    Designed for use in a standard two-semester engineering thermodynamics course sequence. The first half of the text contains material suitable for a basic Thermodynamics course taken by engineers from all majors. The second half of the text is suitable for an Applied Thermodynamics course in mechanical engineering programs. The text has numerous features that are unique among engineering textbooks, including historical vignettes, critical thinking boxes, and case studies. All are designed to bring real engineering applications into a subject that can be somewhat abstract and mathematica

  16. A thermodynamic model of sliding friction

    Directory of Open Access Journals (Sweden)

    Lasse Makkonen

    2012-03-01

    Full Text Available A first principles thermodynamic model of sliding friction is derived. The model predictions are in agreement with the observed friction laws both in macro- and nanoscale. When applied to calculating the friction coefficient the model provides a quantitative agreement with recent atomic force microscopy measurements on a number of materials.

  17. Thermodynamic data bases and calculation code adapted to the modelling of molten core concrete interaction (M.C.C.I.) phenomena, developed jointly by Thermodata and the ''Institut de Protection et de Surete Nucleaire'' (France)

    International Nuclear Information System (INIS)

    Cenerino, G.

    1992-01-01

    An oxide data base containing the main five oxides Al 2 O 3 , CaO, SiO 2 , UO 2 and ZrO 2 of a corium obtained if the reactor core melts through the vessel and slumps into the concrete reactor cavity is developed using the GEMINI2 code. This oxide quinary system study takes into account physical realistic thermodynamical modeling of all the possible equilibrium species of the system. Two applications are presented: the determination of liquidus and solidus temperatures of some selected mixtures of the quinary system (core: UO 2 -ZrO 2 and concrete: Al 2 O 3 -CaO-SiO 2 ), a better modeling of the fission products release by vaporization from the corium. (A.B.). 5 refs., 2 figs

  18. Optimization of powered Stirling heat engine with finite speed thermodynamics

    International Nuclear Information System (INIS)

    Ahmadi, Mohammad H.; Ahmadi, Mohammad Ali; Pourfayaz, Fathollah; Bidi, Mokhtar; Hosseinzade, Hadi; Feidt, Michel

    2016-01-01

    Highlights: • Based on finite speed method and direct method, the optimal performance is investigated. • The effects of major parameters on the optimal performance are investigated. • The accuracy of the results was compared with previous works. - Abstract: Popular thermodynamic analyses including finite time thermodynamic analysis was lately developed based upon external irreversibilities while internal irreversibilities such as friction, pressure drop and entropy generation were not considered. The aforementioned disadvantage reduces the reliability of the finite time thermodynamic analysis in the design of an accurate Stirling engine model. Consequently, the finite time thermodynamic analysis could not sufficiently satisfy researchers for implementing in design and optimization issues. In this study, finite speed thermodynamic analysis was employed instead of finite time thermodynamic analysis for studying Stirling heat engine. The finite speed thermodynamic analysis approach is based on the first law of thermodynamics for a closed system with finite speed and the direct method. The effects of heat source temperature, regenerating effectiveness, volumetric ratio, piston stroke as well as rotational speed are included in the analysis. Moreover, maximum output power in optimal rotational speed was calculated while pressure losses in the Stirling engine were systematically considered. The result reveals the accuracy and the reliability of the finite speed thermodynamic method in thermodynamic analysis of Stirling heat engine. The outcomes can help researchers in the design of an appropriate and efficient Stirling engine.

  19. 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...

  20. Elements of statistical thermodynamics

    CERN Document Server

    Nash, Leonard K

    2006-01-01

    Encompassing essentially all aspects of statistical mechanics that appear in undergraduate texts, this concise, elementary treatment shows how an atomic-molecular perspective yields new insights into macroscopic thermodynamics. 1974 edition.

  1. Electrochemical thermodynamic measurement system

    Science.gov (United States)

    Reynier, Yvan [Meylan, FR; Yazami, Rachid [Los Angeles, CA; Fultz, Brent T [Pasadena, CA

    2009-09-29

    The present invention provides systems and methods for accurately characterizing thermodynamic and materials properties of electrodes and electrochemical energy storage and conversion systems. Systems and methods of the present invention are configured for simultaneously collecting a suite of measurements characterizing a plurality of interconnected electrochemical and thermodynamic parameters relating to the electrode reaction state of advancement, voltage and temperature. Enhanced sensitivity provided by the present methods and systems combined with measurement conditions that reflect thermodynamically stabilized electrode conditions allow very accurate measurement of thermodynamic parameters, including state functions such as the Gibbs free energy, enthalpy and entropy of electrode/electrochemical cell reactions, that enable prediction of important performance attributes of electrode materials and electrochemical systems, such as the energy, power density, current rate and the cycle life of an electrochemical cell.

  2. Workshop on Teaching Thermodynamics

    CERN Document Server

    1985-01-01

    It seemed appropriate to arrange a meeting of teachers of thermodynamics in the United Kingdom, a meeting held in the pleasant surroundings of Emmanuel College, Cambridge, in Sept~mber, 1984. This volume records the ideas put forward by authors, the discussion generated and an account of the action that discussion has initiated. Emphasis was placed on the Teaching of Thermodynamics to degree-level students in their first and second years. The meeting, a workshop for practitioners in which all were expected to take part, was remarkably well supported. This was notable in the representation of essentially every UK university and polytechnic engaged in teaching engineering thermodynamics and has led to a stimulating spread of ideas. By intention, the emphasis for attendance was put on teachers of engineering concerned with thermodynamics, both mechanical and chemical engineering disciplines. Attendance from others was encouraged but limited as follows: non-engineering acad­ emics, 10%, industrialists, 10%. The ...

  3. Black-hole thermodynamics

    International Nuclear Information System (INIS)

    Bekenstein, J.D.

    1980-01-01

    Including black holes in the scheme of thermodynamics has disclosed a deep-seated connection between gravitation, heat and the quantum that may lead us to a synthesis of the corresponding branches of physics

  4. Polyelectrolytes thermodynamics and rheology

    CERN Document Server

    P M, Visakh; Picó, Guillermo Alfredo

    2014-01-01

    This book discusses current development of theoretical models and experimental findings on the thermodynamics of polyelectrolytes. Particular emphasis is placed on the rheological description of polyelectrolyte solutions and hydrogels.

  5. 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.

  6. Phase stability, magnetic, electronic, half-metallic and mechanical properties of a new equiatomic quaternary Heusler compound ZrRhTiIn: A first-principles investigation

    Science.gov (United States)

    Wang, Jia-Xing; Chen, Z. B.; Gao, Y. C.

    2018-05-01

    In this manuscript, we have studied the electronic, magnetic, half-metallic and mechanical properties of a new Zr-based equiatomic quaternary Heusler (EQH) compound, ZrRhTiIn using first-principles calculations. The generalized gradient approximation (GGA) calculation results imply that at its equilibrium lattice constant of 6.70 Å, ZrRhTiIn is a half-metallic material (HMM) with a considerable band gap (Ebg) of 0.530 eV and a spin-filter/half-metallic band-gap (EHM) of 0.080 eV in the minority-spin channel. For ZrRhTiIn, the formation energy of -2.738 eV and the cohesive energy of 21.38 eV indicate that it is a thermodynamically stable material according to theory. The minority-spin EHM arises from the hybridization among Zr-4d, Ti-3d and Rh-4d electrons. The calculated total magnetic moment of ZrRhTiIn is 2 μB, meeting the well-known Slater-Pauling rule Mt = Zt -18. Furthermore, uniform strain and tetragonal strain were applied in this work to examine the magneto-electronic and half-metallic behaviors of the ZrRhTiIn system. Finally, we show that ZrRhTiIn is mechanically stable, ductile and anisotropic.

  7. Thermodynamic features of dioxins’ adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Prisciandaro, Marina [Department of Industrial and Information Engineering and of Economics, University of L’Aquila, Viale Giovanni Gronchi 18, L’Aquila 67100 (Italy); Piemonte, Vincenzo, E-mail: v.piemonte@unicampus.it [Faculty of Engineering, University Campus Biomedico of Rome, Via Alvaro del Portillo 21, Rome 00128 (Italy); Mazziotti di Celso, Giuseppe [Faculty of Bioscience, University of Teramo, Via R. Balzarini, 1, 64100 Teramo (Italy); Ronconi, Silvia [Arta Abruzzo, Department of L’Aquila, Bazzano (AQ), 67100 L’Aquila (Italy); Capocelli, Mauro [Faculty of Engineering, University Campus Biomedico of Rome, Via Alvaro del Portillo 21, Rome 00128 (Italy)

    2017-02-15

    Highlights: • We develop the P-T diagram for six PCDD. • We derive theoretical adsorption isotherms according to the Langmuir’s model. • We calculate K and w{sub max} values for several temperatures. • We estimate the adsorption heat with a good agreement with literature data. - Abstract: In this paper, the six more poisonous species among all congeners of dioxin group are taken into account, and the P-T diagram for each of them is developed. Starting from the knowledge of vapour tensions and thermodynamic parameters, the theoretical adsorption isotherms are calculated according to the Langmuir’s model. In particular, the Langmuir isotherm parameters (K and w{sub max}) have been validated through the estimation of the adsorption heat (ΔH{sub ads}), which varies in the range 20–24 kJ/mol, in agreement with literature values. This result will allow to put the thermodynamical basis for a rational design of different process units devoted to dioxins removal.

  8. Thermal decomposition of solid mixtures of 2-oxy-4,6-dinitramine-s-triazine (DNAM) and phase stabilized ammonium nitrate (PSAN)

    OpenAIRE

    Simões, P. N.; Pedroso, L. M.; Portugal, A. A.; Campos, J. L.

    2000-01-01

    The thermal decomposition of solid mixtures of 2-oxy-4,6-dinitramine-s-triazine (DNAM) and phase stabilized ammonium nitrate (PSAN) at different mass ratios has been studied. Simultaneous thermal analysis (DSC/TG) and thermomicroscopy have been used. It was found that PSAN promotes the lowering of the decomposition temperature of DNAM. The beginning of this process occurs when both components are in the solid state irrespective of the composition. However, the composition appears as the main ...

  9. Phase stability and oxygen non-stoichiometry of SrCo0.8Fe0.2O3-d measured by in-situ neutron diffraction

    NARCIS (Netherlands)

    McIntosh, Steven; McIntosh, S.; Vente, Jaap F.; Haije, Wim G.; Blank, David H.A.; Bouwmeester, Henricus J.M.

    2006-01-01

    The phase stability, oxygen stoichiometry and expansion properties of SrCo0.8Fe0.2O3−δ (SCF) were determined by in situ neutron diffraction between 873 and 1173 K and oxygen partial pressures of 5×10−4 to 1 atm. At a pO2 of 1 atm, SCF adopts a cubic perovskite structure, space group Pm3¯m, across

  10. Study of fatigue and fracture behavior of NbCr{sub 2}-based alloys: Phase stability in Nb-Cr-Ni ternary system

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, J.H.; Liaw, P.K. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering; Liu, C.T. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

    1997-12-01

    Phase stability in a ternary Nb-Cr-Ni Laves phase system was studied in this paper. Their previous study in NbCr{sub 2}-based transition-metal Laves phases has shown that the average electron concentration factor, e/a, is the dominating factor in controlling the phase stability of NbCr{sub 2}-based Laves phases when the atomic size ratios are kept identical. Since Ni has ten out-shell electrons, the substitution of Ni for Cr in NbCr{sub 2} will increase the average electron concentration of the alloy, thus leading to the change of the crystal structures from C15 to C14. In this paper, a number of pseudo-binary Nb(Cr,Ni){sub 2} alloys were prepared, and the crystal structures of the alloys after a long heat-treatment at 1000 C as a function of the Ni content were determined by the X-ray diffraction technique. The boundaries of the C15/C14 transition were determined and compared to their previous predictions. It was found that the electron concentration and phase stability correlation is obeyed in the Nb-Cr-Ni system. However, the e/a ratio corresponding to the C15/C14 phase transition was found to move to a higher value than the predicted one. The changes in the lattice constant, Vickers hardness and fracture toughness were also determined as a function of the Ni content, which were discussed in light of the phase stability difference of the alloys.

  11. A New Perspective on Thermodynamics

    CERN Document Server

    Lavenda, Bernard H

    2010-01-01

    Dr. Bernard H. Lavenda has written A New Perspective on Thermodynamics to combine an old look at thermodynamics with a new foundation. The book presents a historical perspective, which unravels the current presentation of thermodynamics found in standard texts, and which emphasizes the fundamental role that Carnot played in the development of thermodynamics. A New Perspective on Thermodynamics will: Chronologically unravel the development of the principles of thermodynamics and how they were conceived by their discoverers Bring the theory of thermodynamics up to the present time and indicate areas of further development with the union of information theory and the theory of means and their inequalities. New areas include nonextensive thermodynamics, the thermodynamics of coding theory, multifractals, and strange attractors. Reintroduce important, yet nearly forgotten, teachings of N.L. Sardi Carnot Highlight conceptual flaws in timely topics such as endoreversible engines, finite-time thermodynamics, geometri...

  12. Gravity as a thermodynamic phenomenon

    OpenAIRE

    Moustos, Dimitris

    2017-01-01

    The analogy between the laws of black hole mechanics and the laws of thermodynamics led Bekenstein and Hawking to argue that black holes should be considered as real thermodynamic systems that are characterised by entropy and temperature. Black hole thermodynamics indicates a deeper connection between thermodynamics and gravity. We review and examine in detail the arguments that suggest an interpretation of gravity itself as a thermodynamic theory.

  13. On the modelling of microsegregation in steels involving thermodynamic databases

    International Nuclear Information System (INIS)

    You, D; Bernhard, C; Michelic, S; Wieser, G; Presoly, P

    2016-01-01

    A microsegregation model involving thermodynamic database based on Ohnaka's model is proposed. In the model, the thermodynamic database is applied for equilibrium calculation. Multicomponent alloy effects on partition coefficients and equilibrium temperatures are accounted for. Microsegregation and partition coefficients calculated using different databases exhibit significant differences. The segregated concentrations predicted using the optimized database are in good agreement with the measured inter-dendritic concentrations. (paper)

  14. Consistent thermodynamic properties of lipids systems

    DEFF Research Database (Denmark)

    Cunico, Larissa; Ceriani, Roberta; Sarup, Bent

    different pressures, with azeotrope behavior observed. Available thermodynamic consistency tests for TPx data were applied before performing parameter regressions for Wilson, NRTL, UNIQUAC and original UNIFAC models. The relevance of enlarging experimental databank of lipids systems data in order to improve......Physical and thermodynamic properties of pure components and their mixtures are the basic requirement for process design, simulation, and optimization. In the case of lipids, our previous works[1-3] have indicated a lack of experimental data for pure components and also for their mixtures...... the performance of predictive thermodynamic models was confirmed in this work by analyzing the calculated values of original UNIFAC model. For solid-liquid equilibrium (SLE) data, new consistency tests have been developed [2]. Some of the developed tests were based in the quality tests proposed for VLE data...

  15. Systematic vibration thermodynamic properties of bromine

    Science.gov (United States)

    Liu, G. Y.; Sun, W. G.; Liao, B. T.

    2015-11-01

    Based on the analysis of the maturity and finiteness of vibrational levels of bromine molecule in ground state and evaluating the effect on statistical computation, according to the elementary principles of quantum statistical theorem, using the full set of bromine molecular vibrational levels determined with algebra method, the statistical contribution for bromine systematical macroscopic thermodynamic properties is discussed. Thermodynamic state functions Helmholtz free energy, entropy and observable vibration heat capacity are calculated. The results show that the determination of full set of vibrational levels and maximum vibrational quantum number is the key in the correct statistical analysis of bromine systematical thermodynamic property. Algebra method results are clearly different from data of simple harmonic oscillator and the related algebra method results are no longer analytical but numerical and are superior to simple harmonic oscillator results. Compared with simple harmonic oscillator's heat capacities, the algebra method's heat capacities are more consistent with the experimental data in the given temperature range of 600-2100 K.

  16. Fundamental aspects of plasma chemical physics Thermodynamics

    CERN Document Server

    Capitelli, Mario; D'Angola, Antonio

    2012-01-01

    Fundamental Aspects of Plasma Chemical Physics - Thermodynamics develops basic and advanced concepts of plasma thermodynamics from both classical and statistical points of view. After a refreshment of classical thermodynamics applied to the dissociation and ionization regimes, the book invites the reader to discover the role of electronic excitation in affecting the properties of plasmas, a topic often overlooked by the thermal plasma community. Particular attention is devoted to the problem of the divergence of the partition function of atomic species and the state-to-state approach for calculating the partition function of diatomic and polyatomic molecules. The limit of ideal gas approximation is also discussed, by introducing Debye-Huckel and virial corrections. Throughout the book, worked examples are given in order to clarify concepts and mathematical approaches. This book is a first of a series of three books to be published by the authors on fundamental aspects of plasma chemical physics.  The next bo...

  17. Atomistic modeling of thermodynamic equilibrium and polymorphism of iron

    International Nuclear Information System (INIS)

    Lee, Tongsik; Baskes, Michael I; Valone, Steven M; Doll, J D

    2012-01-01

    We develop two new modified embedded-atom method (MEAM) potentials for elemental iron, intended to reproduce the experimental phase stability with respect to both temperature and pressure. These simple interatomic potentials are fitted to a wide variety of material properties of bcc iron in close agreement with experiments. Numerous defect properties of bcc iron and bulk properties of the two close-packed structures calculated with these models are in reasonable agreement with the available first-principles calculations and experiments. Performance at finite temperatures of these models has also been examined using Monte Carlo simulations. We attempt to reproduce the experimental iron polymorphism at finite temperature by means of free energy computations, similar to the procedure previously pursued by Müller et al (2007 J. Phys.: Condens. Matter 19 326220), and re-examine the adequacy of the conclusion drawn in the study by addressing two critical aspects missing in their analysis: (i) the stability of the hcp structure relative to the bcc and fcc structures and (ii) the compatibility between the temperature and pressure dependences of the phase stability. Using two MEAM potentials, we are able to represent all of the observed structural phase transitions in iron. We discuss that the correct reproductions of the phase stability among three crystal structures of iron with respect to both temperature and pressure are incompatible with each other due to the lack of magnetic effects in this class of empirical interatomic potential models. The MEAM potentials developed in this study correctly predict, in the bcc structure, the self-interstitial in the 〈110〉 orientation to be the most stable configuration, and the screw dislocation to have a non-degenerate core structure, in contrast to many embedded-atom method potentials for bcc iron in the literature. (paper)

  18. 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

  19. Thermodynamic analysis of algal biocrude production

    International Nuclear Information System (INIS)

    Beal, C.M.; Hebner, R.E.; Webber, M.E.

    2012-01-01

    Although algal biofuels possess great potential, profitable production is quite challenging. Much of this challenge is rooted in the thermodynamic constraints associated with producing fuels with high energy, low entropy, and high exergy from dispersed materials. In this study, a preliminary thermodynamic analysis is presented that calculates the energy, entropy, and exergy of the intermediate products for algal biocrude production. These values are also used in an initial attempt to characterize the thermodynamic efficiency of that system. The production pathway is simplified by assuming ideal solutions throughout. Results for the energy and exergy efficiencies, and the first-order energy and exergy return on investment, of the system are given. The summary finding is that the first-order energy return on investment in the best case considered could be as high as 520, as compared to 1.7 × 10 −3 in the experimental unit under development. While this analysis shows that significant improvement may be possible, the ultimate thermodynamic efficiency of algal biofuels likely lies closer to the moderate case examined here, which yielded a first-order energy return on investment of 10. For perspective, the first-order energy return on investment for oil and gas production has been estimated in the literature to be ∼35. -- Highlights: ► A first-principles thermodynamic analysis was conducted for algal biocrude production. ► The energy, entropy, and exergy was determined for each intermediate product by assuming the products were ideal solutions. ► The thermodynamic properties were used to calculate the energy and exergy return on investments for three cases. ► It was determined that the energy and exergy return on investments could be as high as ∼500. ► More realistic assumptions for efficient systems yielded return on investments on the order of 10.

  20. Chloride corrosion in biomass-fired boilers – Fe-O-Cl system thermodynamic analysis

    Directory of Open Access Journals (Sweden)

    Kaczmarczyk Robert

    2016-01-01

    The paper presents a thermodynamic analysis of chloride-induced corrosion in the Fe-O-Cl system. The ranges of the metallic, oxide and chloride phase stability are determined within the temperature range T = 750-1000 K. Based on the parametric equations the equilibrium concentration of gaseous phase determined by Deacon reaction are presented. The effect of H2O concentration in the gaseous phase on high-temperature corrosion process and gaseous NaCl influence on NaFeO2 formation in the passive oxide scale layer (FeO/Fe3O4/Fe2O3 are discussed as well. The results are correlated with available in the literature laboratory experimental data and industrial corrosion process observations. Presented thermodynamic analysis is compared with assumptions of “active oxidation” model. The results may be used for experimental research prediction and a corrosion prevention in the industry.

  1. Elementary statistical thermodynamics a problems approach

    CERN Document Server

    Smith, Norman O

    1982-01-01

    This book is a sequel to my Chemical Thermodynamics: A Prob­ lems Approach published in 1967, which concerned classical thermodynamics almost exclusively. Most books on statistical thermodynamics now available are written either for the superior general chemistry student or for the specialist. The author has felt the need for a text which would bring the intermediate reader to the point where he could not only appreciate the roots of the subject but also have some facility in calculating thermodynamic quantities. Although statistical thermodynamics comprises an essential part of the college training of a chemist, its treatment in general physical chem­ istry texts is, of necessity, compressed to the point where the less competent student is unable to appreciate or comprehend its logic and beauty, and is reduced to memorizing a series of formulas. It has been my aim to fill this need by writing a logical account of the foundations and applications of the sub­ ject at a level which can be grasped by an under...

  2. 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.

  3. Thermodynamics and life span estimation

    International Nuclear Information System (INIS)

    Kuddusi, Lütfullah

    2015-01-01

    In this study, the life span of people living in seven regions of Turkey is estimated by applying the first and second laws of thermodynamics to the human body. The people living in different regions of Turkey have different food habits. The first and second laws of thermodynamics are used to calculate the entropy generation rate per unit mass of a human due to the food habits. The lifetime entropy generation per unit mass of a human was previously found statistically. The two entropy generations, lifetime entropy generation and entropy generation rate, enable one to determine the life span of people living in seven regions of Turkey with different food habits. In order to estimate the life span, some statistics of Turkish Statistical Institute regarding the food habits of the people living in seven regions of Turkey are used. The life spans of people that live in Central Anatolia and Eastern Anatolia regions are the longest and shortest, respectively. Generally, the following inequality regarding the life span of people living in seven regions of Turkey is found: Eastern Anatolia < Southeast Anatolia < Black Sea < Mediterranean < Marmara < Aegean < Central Anatolia. - Highlights: • The first and second laws of thermodynamics are applied to the human body. • The entropy generation of a human due to his food habits is determined. • The life span of Turks is estimated by using the entropy generation method. • Food habits of a human have effect on his life span

  4. Thermodynamics of complexity

    DEFF Research Database (Denmark)

    Westerhoff, Hans V.; Jensen, Peter Ruhdal; Snoep, Jacky L.

    1998-01-01

    -called emergent properties. Tendency towards increased entropy is an essential determinant for the behaviour of ideal gas mixtures, showing that even in the simplest physical/chemical systems, (dys)organisation of components is crucial for the behaviour of systems. This presentation aims at illustrating...... that the behaviour of two functionally interacting biological components (molecules, protein domains, pathways, organelles) differs from the behaviour these components would exhibit in isolation from one another, where the difference should be essential for the maintenance and growth of the living state, For a true...... understanding of this BioComplexity, modem thermodynamic concepts and methods (nonequilibrium thermodynamics, metabolic and hierarchical control analysis) will be needed. We shall propose to redefine nonequilibrium thermodynamics as: The science that aims at understanding the behaviour of nonequilibrium systems...

  5. Extended Irreversible Thermodynamics

    CERN Document Server

    Jou, David

    2010-01-01

    This is the 4th edition of the highly acclaimed monograph on Extended Irreversible Thermodynamics, a theory that goes beyond the classical theory of irreversible processes. In contrast to the classical approach, the basic variables describing the system are complemented by non-equilibrium quantities. The claims made for extended thermodynamics are confirmed by the kinetic theory of gases and statistical mechanics. The book covers a wide spectrum of applications, and also contains a thorough discussion of the foundations and the scope of the current theories on non-equilibrium thermodynamics. For this new edition, the authors critically revised existing material while taking into account the most recent developments in fast moving fields such as heat transport in micro- and nanosystems or fast solidification fronts in materials sciences. Several fundamental chapters have been revisited emphasizing physics and applications over mathematical derivations. Also, fundamental questions on the definition of non-equil...

  6. 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 ...

  7. 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...

  8. Concise chemical thermodynamics

    CERN Document Server

    Peters, APH

    2010-01-01

    EnergyThe Realm of ThermodynamicsEnergy BookkeepingNature's Driving ForcesSetting the Scene: Basic IdeasSystem and SurroundingsFunctions of StateMechanical Work and Expanding GasesThe Absolute Temperature Scale Forms of Energy and Their Interconversion Forms of Renewable Energy Solar Energy Wind Energy Hydroelectric Power Geothermal Energy Biomass Energy References ProblemsThe First Law of Thermodynamics Statement of the First Law Reversible Expansion of an Ideal GasConstant-Volume ProcessesConstant-Pressure ProcessesA New Function: EnthalpyRelationship between ?H and ?UUses and Conventions of

  9. Thermodynamics II essentials

    CERN Document Server

    REA, The Editors of

    2013-01-01

    REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Thermodynamics II includes review of thermodynamic relations, power and refrigeration cycles, mixtures and solutions, chemical reactions, chemical equilibrium, and flow through nozzl

  10. Thermodynamics for engineers

    CERN Document Server

    Wong, Kaufui Vincent

    2011-01-01

    Praise for the First Edition from Students: "It is a great thermodynamics text…I loved it!-Mathew Walters "The book is comprehensive and easy to understand. I love the real world examples and problems, they make you feel like you are learning something very practical."-Craig Paxton"I would recommend the book to friends."-Faure J. Malo-Molina"The clear diction, as well as informative illustrations and diagrams, help convey the material clearly to the reader."-Paul C. Start"An inspiring and effective tool for any aspiring scientist or engineer. Definitely the best book on Classical Thermodynamics out."-Seth Marini.

  11. Mechanics, Waves and Thermodynamics

    Science.gov (United States)

    Ranjan Jain, Sudhir

    2016-05-01

    Figures; Preface; Acknowledgement; 1. Energy, mass, momentum; 2. Kinematics, Newton's laws of motion; 3. Circular motion; 4. The principle of least action; 5. Work and energy; 6. Mechanics of a system of particles; 7. Friction; 8. Impulse and collisions; 9. Central forces; 10. Dimensional analysis; 11. Oscillations; 12. Waves; 13. Sound of music; 14. Fluid mechanics; 15. Water waves; 16. The kinetic theory of gases; 17. Concepts and laws of thermodynamics; 18. Some applications of thermodynamics; 19. Basic ideas of statistical mechanics; Bibliography; Index.

  12. Experimental thermodynamics experimental thermodynamics of non-reacting fluids

    CERN Document Server

    Neindre, B Le

    2013-01-01

    Experimental Thermodynamics, Volume II: Experimental Thermodynamics of Non-reacting Fluids focuses on experimental methods and procedures in the study of thermophysical properties of fluids. The selection first offers information on methods used in measuring thermodynamic properties and tests, including physical quantities and symbols for physical quantities, thermodynamic definitions, and definition of activities and related quantities. The text also describes reference materials for thermometric fixed points, temperature measurement under pressures, and pressure measurements. The publicatio

  13. Black Hole Thermodynamics in an Undergraduate Thermodynamics Course.

    Science.gov (United States)

    Parker, Barry R.; McLeod, Robert J.

    1980-01-01

    An analogy, which has been drawn between black hole physics and thermodynamics, is mathematically broadened in this article. Equations similar to the standard partial differential relations of thermodynamics are found for black holes. The results can be used to supplement an undergraduate thermodynamics course. (Author/SK)

  14. Correct thermodynamic forces in Tsallis thermodynamics: connection with Hill nanothermodynamics

    International Nuclear Information System (INIS)

    Garcia-Morales, Vladimir; Cervera, Javier; Pellicer, Julio

    2005-01-01

    The equivalence between Tsallis thermodynamics and Hill's nanothermodynamics is established. The correct thermodynamic forces in Tsallis thermodynamics are pointed out. Through this connection we also find a general expression for the entropic index q which we illustrate with two physical examples, allowing in both cases to relate q to the underlying dynamics of the Hamiltonian systems

  15. 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.

  16. 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.)

  17. 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.)

  18. Thermodynamic studies of different black holes with modifications of entropy

    Science.gov (United States)

    Haldar, Amritendu; Biswas, Ritabrata

    2018-02-01

    In recent years, the thermodynamic properties of black holes are topics of interests. We investigate the thermodynamic properties like surface gravity and Hawking temperature on event horizon of regular black holes viz. Hayward Class and asymptotically AdS (Anti-de Sitter) black holes. We also analyze the thermodynamic volume and naive geometric volume of asymptotically AdS black holes and show that the entropy of these black holes is simply the ratio of the naive geometric volume to thermodynamic volume. We plot the different graphs and interpret them physically. We derive the `cosmic-Censorship-Inequality' for both type of black holes. Moreover, we calculate the thermal heat capacity of aforesaid black holes and study their stabilities in different regimes. Finally, we compute the logarithmic correction to the entropy for both the black holes considering the quantum fluctuations around the thermal equilibrium and study the corresponding thermodynamics.

  19. 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.

  20. Fluctuating Thermodynamics for Biological Processes

    Science.gov (United States)

    Ham, Sihyun

    Because biomolecular processes are largely under thermodynamic control, dynamic extension of thermodynamics is necessary to uncover the mechanisms and driving factors of fluctuating processes. The fluctuating thermodynamics technology presented in this talk offers a practical means for the thermodynamic characterization of conformational dynamics in biomolecules. The use of fluctuating thermodynamics has the potential to provide a comprehensive picture of fluctuating phenomena in diverse biological processes. Through the application of fluctuating thermodynamics, we provide a thermodynamic perspective on the misfolding and aggregation of the various proteins associated with human diseases. In this talk, I will present the detailed concepts and applications of the fluctuating thermodynamics technology for elucidating biological processes. This work was supported by Samsung Science and Technology Foundation under Project Number SSTF-BA1401-13.