20th International CODATA Conference (Times New Roman, 11pt)
Session: Computational informatics: integrating data science with materials modeling

Interactive experimentation and modeling for phase equilibrium

Weiping Gong^a, Marcelle Gaune-Escard^b, Zhanpeng Jin^a

^aState Key Lab of Powder Metallurgy, Central South University, Changsha 410083,

Telephone: +86 731 8877824

Fax: +86 731 8710855

E-mail: weiping_gong@mail.csu.edu.cn

^bEcole polytechnique, Mecanique Energetique, Technopole de Chateau-Gombert,

5 rue Enrico Fermi, 13453 Marseille cedex 13, France.

Phase diagrams are visual representations of the state of a material as a function of temperature, pressure and concentrations of the constituent components and are, therefore, frequently hailed as basic blueprints or roadmaps for materials design, development, processing and basic understanding. While the correlation between thermodynamics and phase equilibrium was established more than a century ago by J.W. Gibbs, it is only modern developments in modelling and computational technology that have made computer calculations of complex phase equilibrium a realistic possibility today. Modelling is crucial in that it allows consistent description of binary systems that can be safely used for further computation of complex multicomponent phase equilibrium

Often the question arises, can we believe the results of modeling? Comparison of calculated results with experimental data available in literature is the most usually employed test method but some times, the best way to get the answer is certainly to couple interactive experimentation and modeling.

Two examples of equilibrium systems, namely the ZrO₂-SrO and TbBr₃-KBr systems were given in this presentation to illustrate these two kinds of methodologies.

The thermodynamic description of the ZrO₂-SrO and TbBr₃-KBr systems was initiated using the available experimental information. Special attention was paid to the stoichiometric compounds SrZrO₃, Sr₄Zr₃O₁₀ and K₃TbBr₆, respectively, to illustrate, how to select an appropriate thermodynamic model based on crystal structure and chemistry information, how to optimise the thermodynamic parameters, how to identify and resolve the inconsistency between various kinds of experimental data, and how to use thermodynamic modelling as a basic tool in the development and optimisation of materials and process. In the present work, the phase transitions in SrZrO₃ were rationalised from thorough analysis of literature information. The existence of the compound Sr₄Zr₃O₁₀ and the decomposition of the compound K₃TbBr₆ at about 592 K were validated. Comparison between the calculated and measured phase diagrams as well as thermodynamic quantities provided the final test of the overall consistence between the reliable experimental information and the present modeling and thermodynamic computation.

Keywords: phase diagram, thermodynamics modeling, interaction, ZrO₂, SrO, SrZrO_3, Sr₄Zr₃O₁₀, TbBr3, KBr, K₃TbBr₆