Properties computedab initiofrom structure database entries: results and perspectives
Y. Le Page, Paul W. Saxe, J. R. Rodgers · Acta Crystallographica Section A Foundations of Crystallography · 2002
The development of multicomponent thermodynamic databases brings to evidence the necessity of crystallographic information in order to identify and model the many phases present.The combination of crystallographic and thermodynamic databases does not only help to solve the problem of naming phases but can also help to define some areas where a more systematic research on phase solubility ranges/stability/mechanisms of order/disorder, for instance, is needed.To identify phases that although the different crystal structure are anyway related by some special lattice defect evolution (e.g.NiAs to CdI2-type, Cu9Al4-type to Cu5Zn8-type) or related by some distortions (NiAs to MnP-type) can simplify the thermodynamic model reducing the number of model parameters.Identification of families with an underlying lattice (e.g., fcc, bcc, hcp and their superlattices), allows to model order/disorder phenomena (e.g., fcc ordering in Cu-Au and Ni-Al) using only a single Gibbs energy for both states, what brings more physical consistency to the modeling resulting even in descriptions of second order transitions (e.g.bcc ordering in Cu-Zn).Only few of these connections are already identified and implemented in the thermodynamic databases.An extended and challenging task is in front of us and it requires the integration of the thermodynamic and crystallographic databases as well as expertise in both fields.Our strategy supported by the Scientific Group Thermodata Europe (SGTE) is presented.