Bengt Hallstedt

Thermodynamic assessment of the copper-oxygen system

The Cu-O system shows complete miscibility between the metallic liquid and the oxide liquid above ∼1623 K and a miscibility gap below that temperature. Because of the practical importance of the system, a wealth of experimental data exists, both on the phase diagram and on the thermodynamic properties. These data have been reviewed, and a consistent set of thermodynamic model parameters has been optimized. An ionic two-sublattice model was used to describe the liquid phase and was found to represent accurately the experimental data.

Thermodynamic Assessment of the Co-O System

The thermodynamic properties of CoO, Co3O4, and the liquid phase were assessed, and an optimized set of parameters of Gibbs energy functions is proposed. The two stable solid oxides, CoO and Co3O4, were both treated as stoichimetric compounds. The paramagneticantiferromagnetic transition of CoO is well represented by a magnetic ordering model. The Co3O4 spinel phase was described as a normal spinel at room temperature and with cation redistribution at high temperatures. A high-temperature anomaly of Co3O4 was interpreted as a normal-inverse spinel transition. An ionic two-sublattice model was used to model the liquid phase. A calculated phase diagram is presented, and values for the thermodynamic properties are compared with experimental data.

The bismuth-oxygen system

The phase diagram and thermodynamics data of the Bi-O system are reviewed and assessed. An optimized consistent thermodynamic description of the system at 1 bar total pressure is presented. The stable solid phases (solid Bi, α-Bi2O3, and δ-Bi2O3) are all treated as stoichiometric. The liquid phase is described by an ionic two-sublattice model, and the gas phase is treated as an ideal solution. Calculated phase diagrams and values for the thermodynamic properties of the bismuth oxides and the liquid are shown and compared with experimental data.

Thermodynamic assessment of the lanthanum-oxygen system

The data on the thermodynamic properties of La2O3 have been reviewed and optimized using the CALPHAD method. A consistent set of parameters is presented. Data on this system are scarce and, with the exception of a few datapoints on substoichiometric La2O3−xn and one measurement of oxygen solubility in La metal, limited to the properties of pure La and pure La2O3. Using the optimized parameters, a tentative phase diagram and stability diagram have been calculated.

The strontium-oxygen system

Abstract Experimental information on the Sue5f8O system is limited to the properties of pure Sr, SrO, SrO 2 , and O. The data on the thermodynamic properties of SrO, SrO 2 , and the liquid are reviewed and a consistent set of Gibbs energy functions for the Srue5f8O system is presented.

Thermodynamic optimization of the Ca-Cu and Sr-Cu systems

Abstract The experimental data on the Ca-Cu and Sr-Cu systems have been assessed and an optimized set of Gibbs energy functions is presented. The few phase diagram data are found to be in agreement with most thermodynamic measurements and the present optimization gives a good reproduction of the current knowledge on these systems.

Modelling of Thermodynamics and Phase Equilibria in Selected Subsystems of the Bi-Sr-Ca-Cu-O System

Results are presented from a present project on the modelling of thermodynamics and phase equilibria of the system Bi-Sr-Ca-Cu-O. Examples of calculated phase diagrams from the Cu-O, Sr-Cu-O and Sr-Ca-Cu-O systems are shown.