Dominika Jendrzejczyk-Handzlik

Electromotive Force Measurements in High-Temperature Systems

Stability of phases existing in chemical systems is determined by its Gibbs free energy designated as G. The relative position of Gibbs free energy surfaces in the G–T–X (composition) space determines stability ranges of respective phases yielding a map called the phase diagram. Since the knowledge of phase equilibria is essential in designing new materials, determination of Gibbs free energy for respective phases is being continued on both theoretical as well as experimental ways. While in principle chemical potentials of pure substances are needed to derive Gibbs free energy of formation of the stoichiometric phases, it is not the case for the phase ( solid or liquid) with variable composition. As an example, in Fig 1, Gm for three different systems is shown. Fig.1a shows free energy of formation of the intermetallic, stoichiometric Mg2Si phase recalculated per one mole of atoms (Turkdogan, 1980). Fig1b illustrates Gibbs energy of formation of one mole of liquid In-Pb solution (Hultgren, 1973). Finally, Fig.1c demonstrates Gibbs energy of formation of the solid phase, wustite ( ‘FeO’) (Spencer & Kubaschewski, 1978).

Thermodynamic properties of liquid silver-indium-tin alloys determined from emf measurements

Abstract The thermodynamic properties of liquid Ag – Sn – In alloys were determined using solid oxide galvanic cells with zirconia electrolyte. The following galvanic cells were employed: Re + kanthal, Agx – Iny – Sn(1−x−y),(In2O3)s.s//ZrO2 + (Y2O3)//NiO, Ni, Pt(I) in the temperature range from 973 to 1273 K, and in the range of indium mole fraction from 0.3 to 0.8. This limitation was imposed by the side reaction between tin in the liquid alloy and solid In2O3. It was also found that the liquid is in equilibrium with the solid solution of oxides. Calorimetric measurements of the heat of mixing were also carried out at constant temperature 1003 K and along one isopleth with XAg/XSn = 1/1. The thermodynamic properties of the liquid phase were described by the Redlich – Kister – Muggianu formula and the phase relations in the ternary system were calculated. The results of calculations were compared with the experimental data which are available from different literature sources.

Thermodynamic properties of liquid copper–antimony–tin alloys determined from e.m.f. measurements

Abstract The thermodynamics properties of liquid Cu–Sn–Sb alloys were determined using solid-oxide galvanic cells with zirconia electrolyte:(1)Re+kanthal,Cux−Sby−Sn(1−x−y),SnO2//ZrO2+(Y2O3)//NiO,Ni,Pt in the temperature range from 998 to 1223 K. The Gibbs free energy of formation of pure solid SnO2 from pure elements was derived. Using electromotive force values measured for the cell with xSn = 1.0, the following temperature dependence was obtained:ΔGf,SnO20=−567903+200.33T(±1000J)[Jmol−1] Activities of tin were determined along three sections of the ternary system specified by the ratio of mole fractions xCu/xSb = 1:3, 1:1, and 3:1. Thermodynamic properties of the liquid phase were described by the Redlich–Kister–Muggianu formula. Using commercial software, phase relations in the ternary system were calculated. The results of the calculations are compared with experimental data available from literature.