Identifying independent components and internal process order parameters in nonequilibrium multicomponent nonstoichiometric compounds
Year: 2025
Type: article
Abstract: In CALPHAD-type thermodynamic databases, nonstoichiometric compounds are typically described by sublattice models where the sublattice site fractions represent the occupation probability of different atomic, ionic or defect species on different sublattices. Here, we develop a general procedure and corresponding linear algebra tools for converting the sublattice site fractions to a combination of independent component compositions and internal process order parameters describing the extent of internal atomic exchange, electronic redox and defect generation reactions. We apply them to a number of nonstoichiometric phases in thermodynamic databases and literature. The general procedure can be applied to constructing thermodynamic databases in terms of internal process order parameters for nonstoichiometric phases in multicomponent systems such as high-entropy oxides and alloys, which can be utilized to model their kinetics of nonequilibrium processes and microstructure evolution.
Source: Calphad
Authors: Yanzhou Ji, Yueze Tan, Long-Qing Chen
Institutions: Pennsylvania State University, The Ohio State University
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,250
Funders: Hamer Foundation, National Science Foundation, U.S. Department of Energy, University of Pennsylvania, Ohio State University, Pennsylvania State University, Materials Research Science and Engineering Center, Harvard University, National Energy Technology Laboratory, Office of Fossil Energy and Carbon Management, Division of Materials Research
OpenAlex ID: W4408075426