Department of Materials Science & Engineering, and ‡Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States.
J Am Chem Soc. 2014 Jan 29;136(4):1628-35. doi: 10.1021/ja411857y. Epub 2014 Jan 15.
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.
我们通过密度泛函理论结合团簇展开和蒙特卡罗模拟研究了三元 Ca(x)Pb(1-x)S 和 Sr(x)Pb(1-x)S 体系中相分离和有序的热力学。与大多数其他三元 III-V 或 IV-VI 半导体合金类似，我们发现 PbS-CaS 的体相分离在热力学上是有利的。然而，我们预测了 PbS-SrS 体系中稳定有序的三元化合物的惊人存在。这些相是以前未报道过的有序岩盐基化合物：SrPb3S4、SrPbS2 和 Sr3PbS4。通过透射电子显微镜观察和带隙测量证实了这些预测有序相的稳定性。我们相信这项工作为结合理论-实验方法来破译多组分硫属化物体系中复杂的相关系铺平了道路。
