title: Theoretical prediction and experimental confirmation of unusual ternary ordered semiconductor compounds in Sr-Pb-S system.
abstract: We examine the thermodynamics of phase separation and ordering in the ternary Ca(x)Pb(1-x)S and Sr(x)Pb(1-x)S systems by density-functional theory combined with a cluster expansion and Monte Carlo simulations. Similar to most other ternary III-V or IV-VI semiconductor alloys, we find that bulk phase separation is thermodynamically preferred for PbS-CaS. However, we predict the surprising existence of stable, ordered ternary compounds in the PbS-SrS system. These phases are previously unreported ordered rocksalt-based compounds: SrPb3S4, SrPbS2, and Sr3PbS4. The stability of these predicted ordered phases is confirmed by transmission electron microscopy observations and band gap measurements. We believe this work paves the way for a combined theory-experiment approach to decipher complex phase relations in multicomponent chalcogenide systems.
authors.affiliation: Department of Materials Science & Engineering, and ‡Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States.
authors.forename: Shiqiang
authors.initials: S
authors.lastname: Hao
authors.forename: Li-Dong
authors.initials: LD
authors.lastname: Zhao
authors.forename: Chang-Qiang
authors.initials: CQ
authors.lastname: Chen
authors.forename: Vinayak P
authors.initials: VP
authors.lastname: Dravid
authors.forename: Mercouri G
authors.initials: MG
authors.lastname: Kanatzidis
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Wolverton