Theoretical Study of the Filling Fraction Limit of Fe-Substituted Ba-Filled Skutterudite Ba_yFe_(4x)Co_(4-4x)Sb_(12)

摘要

Theoretical study of the filling fraction limit (FFL) of the Fe-substituted Ba-filled skutterudite was carried out via first principle method calculations. The lattice constant of Ba_yFe_(4x)Co_(4-4x)Sb_(12) increases with the Ba filling fraction under fixed Fe content while it does not simply increases with Fe content under fixed Ba filling fraction. The FFL is determined by the competition between the formation of filled skutterudite phases and the corresponding secondary phases. The FFL of Ba in the Fe-substituted CoSb_3 skutterudites increases monotonically from 37.5% with Fe content of 0 to 100% with Fe content of -50%. The most stable composition of the Ba_yFe_(4x)Co_(4-4x)Sb_(12) is expected to be Ba_yFe_(4x)Co_(4-4x)Sb_(12).