Thermodynamic properties of Ge-Mn melts

The enthalpies of mixing of Ge-Mn melts are determined in the range 1550–1840 by isoperibol calorimetry.The formation of these melts is shown to be accompanied by significant heat release: _mix H _max = -25.12 ± 1.4 kJ/mol at x _Mn = 0.7. Ge activity is evaluated from the position of the liquidus line. The Mn and Ge activities in this system exhibit negative deviations from Raoults law. The new and earlier data on the thermodynamic properties of Ge-Mn melts are analyzed.Translated from Neorganicheskie Materialy, Vol. 41, No. 2, 2005, pp. 240–245.Original Russian Text Copyright © 2005 by Kotova, Beloborodova, Zinevich, Dubina, Sudavtsova.     

Thermodynamic properties of Ge-Ni melts

Using high-temperature isoperibol calorimetry, we have determined the partial enthalpy of mixing of nickel in Ge-Ni melts at 1800 ± 3 K in the composition range 0 < x _Ni < 0.7 (\(\Delta _{mix} \bar H^\infty \) (Ni) = ?76.0 ± 4.8 kJ/mol). The results have been used to evaluate the partial enthalpy of mixing of germanium and the integral enthalpy of mixing (Δ_mix H _min = ?37.9 ± 0.6 kJ/mol at x _Ni = 0.6). The thermochemical data and germanium activity in Ge-Ni melts have been analyzed in comparison with those reported earlier, and the most reliable thermodynamic functions of the Ge-Ni melts at 1870 K have been determined.     

Thermodynamic properties of Al-Mn melts

The thermochemical properties of Al-Mn melts have been studied at 1835 ± 3 K by high-temperature calorimetry under isoperibolic conditions. The Δ_mix H and Δ_mix \(\overline H _i\), data obtained correlate well with earlier data obtained at a lower temperature of 1628 K. The enthalpies of formation of manganese aluminides determined by calorimetry agree only qualitatively with the Δ_mix H of Al-Mn melts. We have calculated the partial and integral entropies of mixing of Al-Mn melts. Analysis of the entire set of thermodynamic properties indicates that, in liquid Al-Mn alloys, the interaction between dissimilar atoms is significant even well above the liquidus temperature.     

Thermodynamic properties of Si-Y and Ge-Y melts

Using high-temperature isoperibol calorimetry, we have determined the partial enthalpy of mixing of yttrium in Si-Y and Ge-Y melts at 1770 (1780) ± 5 K in the composition ranges 0 < x _Y < 0.2 (0.4). The results have been used to evaluate the integral enthalpies of mixing for these melts. Their formation has been shown to be accompanied by significant heat release. The mixing enthalpies of the liquid alloys have been optimized using the present and earlier data. The activities of the components of Si-Y and Ge-Y melts have been evaluated from the liquidus coordinates in the corresponding phase diagrams and have been found to exhibit very large negative deviations from Raoult’s law.     

Thermodynamic properties of Eu-Pt and Al-Eu-Pt melts

The partial and integral enthalpies of mixing of Eu-Pt melts were determined by calorimetry at 1300 K in the composition range 0 < x _Pt < 0.36. The first partial enthalpy of mixing of Pt was found to be ?171 ± 2 kJ/mol. The thermodynamic properties of the Eu-Pt melts were modeled in terms of ideal associated solution theory in wide composition and temperature ranges. The results indicate that the activities of the components have large negative deviations from Raoult’s law and that the integral Gibbs energy and enthalpy of mixing have a minimum near x _Pt = 0.7. The enthalpy and excess Gibbs energy of mixing of Al-Eu-Pt ternary melts were modeled using our and others’ data and Kohler’s equation.     

Thermodynamic behaviour of undercooled melts

The Gibbs free energy difference (ΔG) between the undercooled liquid and the equilibrium solid phases has been studied for the various kinds of glass forming melts such as metallic, molecular and oxides melts using the hole theory of liquids and an excellent agreement is found between calculated and experimental values of ΔG. The study is made for non-glass forming melts also. The temperature dependence of enthalpy difference (ΔH) and entropy difference (ΔS) between the two phases, liquid and solid, has also been studied. The Kauzmann temperature (T ₀) has been estimated using the expression for ΔS and a linear relation is found between the reduced glass transition temperature (T _g/T _m) and (T ₀)/T _m). The residual entropy (ΔS _R) has been estimated for glass forming melts and an attempt is made to correlate ΔS _R,T _g,T ₀, andT _m which play a very important role in the study of glass forming melts.     

Thermodynamic activities in silicon binary melts

The thermodynamic activities in the silicon binary melts with Al, Ca, Mg, Fe, Ti, Zn, Cu, Ag, Au, Sn, Pb, Bi, Sb, Ga, In, Pt, Ni, Mn and Rh are studied. The silicon activities along the liquidus are calculated through a quasi-regular solution model using the recently determined liquidus constants for the silicon binary systems. The silicon activities at its melting point are calculated considering regular solution approximation. The activities of the other melt component at the silicon melting point are also calculated through the graphical integration of the Gibbs–Duhem equation for the activity coefficient, which are further utilized to determine the corresponding activities along the liquidus. The calculated activities are presented graphically, and it is indicated that the results are consistent with the reported activity data in the literature. The activities in the dilute solutions are also calculated graphically. Moreover, the activities of particular dilute solute elements in silicon are calculated through a simple formula, which is a function of the liquidus constants.     

Thermodynamic properties of Mn-Y-Si(Ge,Sn, Pb,C) melts

The effect of Group IVA elements on the integral enthalpy of mixing of Mn-Y-Si(Ge, Sn, Pb, C) melts has been studied using the mixing enthalpies of Mn-Y-Si(Ge) melts determined earlier by calorimetry at 1770 ± 5 K. Since the thermochemical properties of Mn-Y-C(Sn, Pb) melts are unexplored, they have been calculated by the Bonnier-Caboz method using reliable data for the constituent binary systems. To this end, we have performed critical evaluation of the phase diagrams and thermochemical data for the constituent binary systems and have compared the enthalpies of formation of solid Δ_f H and liquid Δ_mix H binary alloys. The results indicate that, among liquid Mn-Y-IVA alloys, the formation of Mn-Y-Ge melts is the most exothermic. The thermochemical properties of all the ternary alloys examined are determined by the properties of the Y-Si(Ge, Sn, Pb, C) constituent binary systems, which have the highest exothermic mixing enthalpies.     

Thermodynamic properties of nickel

This work reviews and discusses the data and information on the thermodynamic properties of nickel available through May 1984. These properties include heat capacity, enthalpy, enthalpy of transition and melting, vapor pressure, and enthalpy of vaporization. The recommended values for heat capacity cover the temperature range from 1 to 3200 K. The recommended values for enthalpy, entropy, Gibbs energy function, and vapor pressure cover the temperature range from 298.15 to 3200 K.     

Thermodynamic properties of n-butane

Equations are derived and used to calculate a table of thermodynamic properties of n-butane in the saturated state.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 47, No. 3, pp. 407–410, September, 1984.     

Thermodynamic properties of vanadium

This work reviews and discusses the data and information on the various thermodynamic properties of vanadium available through March 1985. These include the heat capacity and enthalpy, enthalpy of melting, vapor pressure, and enthalpy of vaporization. The existing data have been critically evaluated and analyzed, and the recommended values for heat capacity, enthalpy, entropy, and Gibbs energy function covering the temperature range from 1 to 3800 K have been generated. These values are referred to temperatures based on IPTS-1968. The units used for various properties are joules per mole (J · mol^–1). The estimated uncertainties in the heat capacity are ±3% below 15 K, ±10% from 15 to 150 K, ±3% from 150 to 298.15 K, ±2% from 298.15 to 1000 K, ±3% from 1000 to the melting point (2202 K), and ±5% in the liquid region.Paper presented at the Ninth Symposium on Thermophysical Properties, June 24–27, 1985, Boulder, Colorado, U.S.A.     

Thermodynamic properties of aluminum

This work reviews and discusses the data on the thermodynamic properties of aluminum available through May 1984. However, two papers dated 1985 which are useful to this work are also included. These properties include heat capacity, enthalpy, enthalpy of transition and melting, vapor pressure, and enthalpy of vaporization. The recommended values for heat capacity cover the temperature range from 0.1 to 2800 K. The recommended values for enthalpy, entropy, Gibbs energy function, and vapor pressure cover the temperature range from 298.15 to 2800 K.     

Thermodynamic properties of titanium

This work reviews and discusses the data and information on the thermodynamic properties of titanium available through May 1984. These properties include heat capacity, enthalpy, enthalpy of transition and melting, vapor pressure, and enthalpy of vaporization. The recommended values for heat capacity cover the temperature range from 1 to 3800 K. The recommended values for enthalpy, entropy, Gibbs energy function, and vapor pressure cover the temperature range from 298.15 to 3800 K.     

Thermodynamic properties of InP

The emf of an electrochemical cell of the type (?) W, In(l) | ZnCl₂ + KCl + NaCl + InCl | (InP(s) + P(black)), W(+) has been measured in the temperature range 500–600 K. The change in the chemical potential of this cell (Δμ_In=?52.50 + 19.01 × 10^?3 T kJ/mol) corresponds to the reaction In(l) + P(black) → InP(s). The standard enthalpy of formation of InP from solid indium and white phosphorus is determined to be Δ_f H ⁰(298 K) = ?69.3 ± 3 kJ/mol. We have performed thermodynamic analysis of the literature data for the In-P system, with consideration for different phosphorus allotropes.     

Thermodynamic properties of chromium

This paper is intended as a short review of the results of thermodynamic measurements available for pure chromium. The various experimental data are combined and a set of parameters describing the Gibbs energy of each individual phase as a function of temperature and pressure is obtained.     

Thermodynamic properties of n-hexane

Specific volumes and isobaric heat capacity measurements are reported for n-hexane. The measurements were made in the liquid and vapor phases at temperatures from the triple point and also cover a wide region around the critical point. The thermal, caloric, and acoustic data from our own investigation as well as those of a number of other authors are fitted to a single equation of state with 32 constants. This equation yields to all thermodynamic properties of n-hexane in the temperature range 180 to 630 K and pressures up to 100 MPa. The data in the critical region have been analyzed in terms of a scaled equation of state.     

Thermodynamic properties of n-pentane

Specific volumes and isobaric heat capacity measurements are reported for n-pentane. The measurements were made in the liquid and vapor phases at temperatures ranging from the triple point (173 K) to the onset of dissociation temperature (700 K) and pressures up to 100 MPa including a wide region around the critical point. We are able to fit our data, as well as those of a number of other authors, to a single equation of state with 30 constants. This equation yields the density of n-pentane in the temperature range from 280 to 650 K at pressures up to 80 MPa and the caloric properties up to 500 K. Additional experimental investigations of the thermodynamic properties are required for temperatures above 500 K. Interpolating equations for the caloric properties on the saturated line and in the critical region are also presented.     

Thermodynamic properties for the alternative refrigerants

Models commonly used to calculate the thermodynamic properties of refrigerants are summarized. For pure refrigerants, the virial, cubic, Martin-Hou, Benedict-Webb-Rubin, and Helmholtz energy equations of state and the extended corresponding states model are discussed. High-accuracy formulations for 16 refrigerants are recommended. These models may be extended to mixtures through the use of mixing rules applied either to the parameters of the equation of state or to some property of the mixture components. Mixtures of a specific composition may also be modeled as a pseudo-pure fluid. Five mixture models, employing four distinct approaches, have been compared by a group working under the auspices of the International Energy Agency. These comparisons show all five models to be very capable in representing mixture properties. No single model was best in all aspects, but based on its combination of excellent accuracy and great generality, we recommend the mixture Helmholtz energy model as the best available.Experimental data are essential to both fit the adjustable parameters in property models and to assess their accuracy. We present a survey of the data available for mixtures of the HFC refrigerants R32, R125, R143a, R134a, and R152a and for mixtures of the natural refrigerants propane, butane, isobutane, and carbon dioxide. More than 60 data references are identified. Further data needs include caloric data for additional mixtures, comprehensive pressure-density-temperature data for additional mixture compositions, and improved accuracy for vapor-liquid equilibria data.