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[en] Values or limits are provided for the Gibbs free energies of formation of A/sub n/B/sub m/ intermetallic compounds for 84 binary systems. A elements are: Li, Be, Mg, Ca, Sr, Ba, Al, Si, Sc, Ti, V, Mn, Fe, Co, Ni, Y, Zr, Nb, Hf, Ta, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Th, U, and Pu. B elements are Fe, Co, Ni, Ru, Rh, Pd, Ag, Re, Os, Ir, Pt, and Au. The significance and applications of this information are discussed
[en] The LiF-ThF4 system has been considered as reference fuel solvent for Molten Salt Reactor. The high temperature interaction of LiF-ThF4 leads to formation of a number of complex fluoride compounds. The study is focused on determination of experimental thermodynamic properties of the compounds in this system. The Gibbs energy of formation of LiThF5(s) and LiTh2F9 (s) has been measured by solid electrolyte Galvanic cell method. (author)
[en] A quadrupole mass spectrometer coupled to a Knudsen cell was used to determine the Gibbs free energy of formation of ThRh3(S) in the temperature range 1068 ≤ T (K) ≤ 1214.5. Gibbs free energy as a function of temperature was derived to be: ΔfG0(ThRh3s) (kJ.mol-1)-363.18 +0.0634T(K)
[en] Uranyl materials form as a result of the oxidation and alteration of uraninite, UO2+x. These uranyl phases are also important alteration products of the corrosion of UO2 in used nuclear fuels under oxidizing conditions. However, the thermodynamic database for these phases is extremely limited. The Gibbs free energies and enthalpies for uranyl phases are estimated based on a method that sums polyhedral contributions. The molar contributions of the structural components to ΔGf0 and ΔHf0 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 ΔGf0 and ΔHf0 for the uranyl phases used in the model are 0.08 and 0.10%, respectively, well below the limits of uncertainty for the experimentally determined values. To analyze the reliability of the predicted ΔGf0 values, activity-activity diagrams in SiO2-CaO-UO3-H2O and CO2-CaO-UO3-H2O systems at 298.15 K and 1 bar were constructed using the predicted ΔGf.298.150 values for the relevant U6+ phases. There is good agreement between the predicted mineral stability relations and field occurrences, thus providing confidence in this method for the estimation of ΔGf0 and ΔHf0 of the U6+ phases
[en] The open terminal voltage of a lithium ion battery is measured at temperatures ranging from 0 °C to 50 °C in increments of 10 °C. Primary focus is on three states of charge of the battery (full charge, late life, charge depletion). Estimates of the enthalpy, ΔH, and the entropy, ΔS, of the battery reaction are made using the established thermochemical relationship between the open terminal voltage and the Gibbs free energy, ΔG. As expected, ΔS is found to be dependent on the state of charge. The enthalpy also shows some dependence on the state of charge, which is at variance with the ideal Nernstian behavior. This may attributed to non-equivalence of intercalation sites as well as near neighbor interactions. Furthermore, the rate of discharge has little apparent effect on these results. An equilibration time well in excess of 20 hours is also observed.
[en] Rank distributions are collections of positive sizes ordered either increasingly or decreasingly. Many decreasing rank distributions, formed by the collective collaboration of human actions, follow an inverse power-law relation between ranks and sizes. This remarkable empirical fact is termed Zipf’s law, and one of its quintessential manifestations is the demography of human settlements — which exhibits a harmonic relation between ranks and sizes. In this paper we present a comprehensive statistical-physics analysis of rank distributions, establish that power-law and exponential rank distributions stand out as optimal in various entropy-based senses, and unveil the special role of the harmonic relation between ranks and sizes. Our results extend the contemporary entropy-maximization view of Zipf’s law to a broader, panoramic, Gibbsian perspective of increasing and decreasing power-law and exponential rank distributions — of which Zipf’s law is one out of four pillars
[en] Solubility of carnotite in carbonated water is about three order more than in pure water. Average from synthetic and natural samples gave an equilibrium constant, Keq of 10-18.05. Calculated standard Gibbs free energies of formation for carnotite is -1272.4 kcal. Standard Gibbs free energies of formation for tyuyamunite is predicted to be -1264.4 kcal, which gave its Keq as 10-14.07. (Author)
[en] In this paper the study of the irreversible availability, already adopted for discrete systems, is generalized to field theory. The general equations are derived and the stationary unidimensional case is solved analytically
[en] We consider thermodynamics of homogeneous systems in the framework of Caratheodory's approach. We work in a configuration space where independent variables are all extensive, and we show that the requirement for homogeneity symmetry of the integrable 1-form δQrev, which represents the infinitesimal heat exchanged reversibly by a thermodynamic system, allows to find immediately and explicitly an integrating factor by means of elementary tools of differential geometry. The foliation of the thermodynamic manifold is associated in a natural way with an extensive potential, which is then identified with the metrical entropy S. Both S and the absolute temperature T are derived quantities in this framework. The entropy S corresponds to the fundamental relation in the entropy representation according to Gibbs' approach to thermodynamics, thus an explicit connection between Caratheodory's approach and Gibbs' approach to thermodynamics is obtained. The relation with statistical mechanical formalism is also pointed out.