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Poster 'Optical and Thermodynamic Properties of Pure- and La-doped SrTiO3' presented by NETL at the 15th International Symposium on Solid Oxide Fuel Cells; Hollywood, FL; July 23-28, 2017
The mechanical, electronic, and thermodynamic properties of typical layered structure yttrium diborocarbides (YB{sub 2}C{sub 2}) were investigated by the density functional theory. The calculated lattice constants were slightly higher than the available experimental data. The elastic constants revealed that YB{sub 2}C{sub 2} was mechanically stable. The bulk modulus (190.8 GPa), shear modulus (127.4 GPa), Young’s modulus (312.7 GPa), Poisson’s ratio (0.227), and Vickers hardness (18–19 GPa) were obtained, and the ductility, plasticity, and elastic anisotropy were further analyzed. The total and partial density of states were also calculated, indicating that the metallic character was mainly attributed to the contribution from Y-4d states and weakly hybridized with the 2p states from the B and C atoms. Finally, we obtained the Debye, melting, and the superconducting transition temperatures of YB{sub 2}C{sub 2} as 824, 2239 and 2.38 K, respectively. Our study showed that YB{sub 2}C{sub 2} offers potential in superconductivity or ultrahigh temperature applications.
Gaseous and liquid neon thermodynamic properties with extrapolation to temperature and pressure ranges not available from experiment
General methods for combining interactions between particles characterised by non-identical intermolecular potentials are investigated. The combination methods are tested by performing molecular dynamics simulations to determine the pressure, energy, isochoric and isobaric heat capacities, thermal expansion coefficient, isothermal compressibility, Joule-Thomson coefficient, and speed of sound of 10-5 + 12-6 Mie potential binary mixtures. In addition to the two non-identical Mie potentials, mixtures are also studied with non-identical intermolecular parameters. The combination methods are compared with results obtained by simply averaging the Mie exponents. When either the energy or size parameters are non-identical, very significant differences emerge in the thermodynamic properties predicted by the alternative combination methods. The isobaric heat capacity is the thermodynamic property that is most affected by the relative magnitude of the intermolecular potential parameters and the method for combining non-identical potentials. Either the arithmetic or geometric combination of potentials provides a simple and effective way of performing simulations involving mixtures of components characterised by non-identical intermolecular potentials, which is independent of their functional form.
Motivated by possible relation between Born–Infeld type nonlinear electrodynamics and an effective low-energy action of open string theory, asymptotically Reissner–Nordström black holes whose electric field is described by a nonlinear electrodynamics (NLED) are studied. We take into account a four dimensional topological static black hole ansatz and solve the field equations, exactly, in terms of the NLED as a matter field. The main goal of this paper is investigation of thermodynamic properties of the obtained black holes. Moreover, we calculate the heat capacity and find that the nonlinearity affects the minimum size of stable black holes. We also use Legendre-invariant metric proposed by Quevedo to obtain scalar curvature divergences. We find that the singularities of the Ricci scalar in Geometrothermodynamics (GTD) method take place at the Davies points. -- Highlights: •We examine the thermodynamical properties of black holes in Einstein gravity with nonlinear electrodynamics. •We investigate thermodynamic stability and discuss about the size of stable black holes. •We obtain analytical solutions of higher dimensional theory.
Thermodynamic properties of binary Gd-Bi alloys (mole fraction, x Gd = 0.02–0.35) were determined using electromotive force (emf) measurements in molten LiCl-KCl-GdCl 3 electrolyte in complement with structural, microstructural, and thermal characterization. X-ray diffractometry (XRD) and scanning electron microscopy (SEM) identified the phase constituents of Gd-Bi alloys (x Gd = 0.02–0.35) as Bi matrix and GdBi compound. According to differential scanning calorimetry (DSC) measurements up to 1250 K, a eutectic transition [L = Bi + GdBi] was observed at 543 K but the reported peritectic transition [L + GdBi = GdBi 2 ] was not detected, suggesting the absence of the GdBi 2 compound. Based on structural, microstructural, and thermal characterization of Gd-Bi alloys (x Gd = 0.02–0.35), the GdBi 2 compound was not detected, and its thermodynamic stability is questionable. The emf of Gd-Bi alloy (x Gd = 0.16) at 700–1048 K relative to Gd(s) was measured by electrodepositing pure Gd metal at 25 K increments. Further, the emf values of Gd-Bi alloys were determined via coulometric titration of Gd into liquid Bi using a two-phase [L + GdBi] alloy as a reference electrode at 773–973 K. The solubility of Gd in liquid Bi was also estimated to be 0.50 mol% (773 K), 0.99 mol% (873 K), and 2.21 mol% (973 K) and the excess partial molar Gibbs energy (Δ$\mathrm{\bar{G}^{ex}_{Gd}}$) of liquid Gd-Bi alloys was as low as 65 kJ mol –1 , indicating strong chemical interactions between Gd and Bi.
An extremely compact object (ECO) is defined as a quantum object without horizon, whose radius is just a small distance s outside its Schwarzschild radius. We show that any ECO of mass M in d + 1 dimensions with s << (M/m p ) 2/(d-2)(d+1) lp must have (at leading order) the same thermodynamic properties—temperature, entropy and radiation rates—as the corresponding semiclassical black hole of mass M. An essential aspect of the argument involves showing that the Tolman–Oppenheimer–Volkoff equation has no consistent solution in the region just outside the ECO surface, unless this region is filled with radiation at the (appropriately blueshifted) Hawking temperature. In string theory it has been found that black hole microstates are fuzzballs—objects with no horizon—which are expected to have a radius that is only a little larger than the horizon radius. Thus the arguments of this paper provide a nice closure to the fuzzball paradigm: the absence of a horizon removes the information paradox, and the thermodynamic properties of the semiclassical hole are nonetheless recovered to an excellent approximation.
The thermodynamic properties of natural carrollite with a formula Cu 0.92 Co 2.07 S 4 are studied using low temperature heat capacity and high temperature oxidative solution calorimetry. The standard thermodynamic functions at 298.15 K are: C p,m °, S m °, H m °, and Φ m ° are 158.48 J∙K −1 ∙mol −1 , 176.33 J∙K −1 ∙mol −1 , 28.40 kJ∙mol −1 , and 81.07 kJ∙mol −1 with an estimated error of 1%. The enthalpies (Δ f H), entropies (Δ f S), and Gibbs energies of formation (Δ f G) from elements at 298.15 K are: −344.46 ± 12.87 kJ∙mol −1 , −45.22 ± 1.81 J∙K −1 ∙mol −1 , and −331.14 ± 1.89 J∙K −1 ∙mol −1 . The stability of carrollite relative to the elements is demonstrated with a negative Gibbs energy (ΔG r °) of formation for several temperatures between 0 and 300 K. Furthermore, a superconductivity transition, which has been observed previously for synthetic carrollite, is confirmed by both the low temperature heat capacity and magnetization measurements.
Remote sensing cross-beam cross correlation methods of determining spatially resolved average thermodynamic properties
Entropy, enthalpy, and density values for mixtures of liquid and vapor para hydrogen and mixtures of liquid and vapor oxygen - thermodynamic properties
The aging- or radiation-induced hardening of Cu/Mn/Ni precipitates in Fe alloys is one of property degradation mechanisms in structural materials in nuclear reactors. Experiments show that aging or radiation leads the formation of Cu-rich precipitates, and the addition of Mn or Ni elements enhances the precipitation kinetics. In this study, the phase-field model coupled with the constrained string method have been applied to investigate the thermodynamic properties of critical nuclei such as the minimum energy path of Cu/Mn/Ni precipitation in Fe-Cu-Mn and Fe-Cu-Ni ternary alloys. The chemical free energies used in the model are taken from CALPHAD. The simulation results show that the formation of Cu/Mn/Ni clusters needs to overcome an energy barrier, and the precipitate has a Core-Shell structure. The thermodynamic properties of the critical nucleus are influenced by temperature and Cu/Mn/Ni overall concentrations, which are in accordance with the simulation results as well as the experimental observations.
We report that the performance of La x Sr 1- x Co 1- y Fe y O 3- δ perovskite systems in applications such as solid oxide fuel cells and catalysis is related to the proportion of substitution atoms. Using a density functional theory method, we investigate the doping effect on the electronic, optical, and thermodynamic properties of La x Sr 1- x Co 1- y Fe y O 3- δ ( x / y = 0.25, 0.5, 0.75). Our results show that La doping introduces an empty state and pushes the Fermi level upwards. The doping Fe derived states locate away from the Fermi level as compared with Co states. From the results of optical absorption, the peak at 200–300 nm is enhanced and experiences a blue-shift with increasing La concentration. The corresponding peak at 400–700 nm also shows a blue-shift induced by both La and Fe doping, and it could be enhanced by Fe doping while being suppressed by La doping. And the peak above 1500 nm is enhanced by the cooperation of La and Fe doping. From thermodynamic calculations via an Ellingham diagram, it is found that the parent SrCoO 3 is the most favorable composition for releasing O 2 , with both La and Fe doping hampering the reduction reaction. Therefore, the optical and thermodynamic properties of La x Sr 1- x Co 1- y Fe y O 3- δ could be adjusted by special doping values.
The thermodynamic properties of Ca-Bi alloys were determined by electromotive force (emf) measurements to assess the suitability of Ca-Bi electrodes for electrochemical energy storage applications. Emf was measured at ambient pressure as a function of temperature between 723 K and 1173 K using a Ca(s)vertical bar CaF2(s)vertical bar Ca(in Bi) cell for twenty different Ca-Bi alloys spanning the entire range of composition from chi(Ca) = 0 to 1. Reported are the temperature-independent partial molar entropy and enthalpy of calcium for each Ca-Bi alloy. Also given are the measured activities of calcium, the excess partial molar Gibbs energy of bismuth estimated from the Gibbs-Duhem equation, and the integral change in Gibbs energy for each Ca-Bi alloy at 873 K, 973 K, and 1073 K. Calcium activities at 973 K were found to be nearly constant at a value a(Ca) = 1 x 10(-8) over the composition range chi(Ca) = 0.32-0.56, yielding an emf of similar to 0.77 V. Above chi(Ca) = 0.62 and coincident with Ca5Bi3 formation, the calcium activity approached unity. The Ca-Bi system was also characterized by differential scanning calorimetry over the entire range of composition. Based upon these data along with the emf measurements, a revised Ca-Bi binary phase diagram is proposed. (C) 2011 Elsevier Ltd. All rights reserved.
Thermodynamic properties of erbium hydrogen binary system evaluated for use as low pressure standard
Thermodynamic properties of liquid cesium-mercury solutions
The equilibrium composition and the thermodynamic properties of the mixture resulting from the decomposition of uranium hexafluoride is calculated for temperatures ranging from 600 K to 4000 K at pressures from 0.01 atmospheres to 10 atmospheres.
In the present study, we investigated the thermodynamic properties of uranium dioxide (UO2) by molecular dynamics (MD) simulations. As for solid UO2, the lattice parameter, density, and enthalpy obtained by MD simulations were in good agreement with existing experimental data and previous theoretical predictions. The calculated thermal conductivities matched the experiment results at the midtemperature range but were underestimated at very low and very high temperatures. The calculation results of mean square displacement represented the stability of uranium at all temperatures and the high mobility of oxygen toward 3000 K. By fitting the diffusivity constant of oxygen with the Vogel-Fulcher-Tamman law, we noticed a secondary phase transition near 2006.4 K, which can be identified as a ‘‘strong’’ to ‘‘fragile’’ supercooled liquid or glass phase transition in UO2. By fitting the oxygen diffusion constant with the Arrhenius equation, activation energies of 2.0 and 2.7 eV that we obtained were fairly close to the recommended values of 2.3 to 2.6 eV. Xiangyu Wang, Bin Wu, Fei Gao, Xin Li, Xin Sun, Mohammed A. Khaleel, Ademola V. Akinlalu and Li Liu
The structural, electronic, magnetic, elastic, and thermodynamic properties of cubic AMO{sub 3} perovskites (A = Eu, M = Ga, In) have been successfully studied within density functional theory using full-potential linearized augmented plane wave (FP-LAPW). The structural study reveals that both the compounds are stable in ferromagnetic states. The GGA + U calculated spin-polarized electronic band and density of states present the half-metallic nature of both the compounds. The magnetic moments calculated with different approximations were found to be approximately 6 μ{sub B} for EuGaO{sub 3} and approximately 7 μ{sub B} for EuInO{sub 3}. From elastic calculation, the three independent elastic constants (C{sub 11}, C{sub 12}, C{sub 44}) have been acquired to yield the mechanical properties like Young modulus (Y ), shear modulus (G), Poisson ratio (ν), and anisotropic factor (A). The calculated values of B/G show that both the compounds are ductile in nature. The thermodynamic study was also accomplished by exploring the thermodynamic parameters like specific heat, heat capacity, thermal expansion, Grüneisen parameter, Debye temperature, etc. within the temperature range 0 to 900 K and pressure range 0 to 50 GPa.