Authors
Chen, Haijie; McClain, Rebecca; Shen, Jiahong; He, Jiangang; Malliakas, Christos; Spanopoulos, Ioannis; Zhang, Chi; Zhao, Chendong; Wang, Yang; Li, Qiang; Chung, Duck Young; Kwok, Wai-Kwong; Kanatzidis, Mercouri
Abstract
We report three new mixed-anion two-dimensional(2D) compounds: SrFPbBiS3, SrFAg0.5Bi1.5S3, and Sr2F2Bi2/3S2.Their structures as well as the parent compound SrFBiS2wererefined using single-crystal X-ray diffraction data, with thesequence of SrFBiS2, SrFPbBiS3, and SrFAg0.5Bi1.5S3defining thenew homologous series SrFMnBiSn+2(M = Pb, Ag0.5Bi0.5;n= 0, 1).Sr2F2Bi2/3S2has a different structure, which is modulated with aqvector of 1/3b*and was refined in superspace groupX2/m(0 beta 0)00 as well as in the 1x3x1 superstructure with spacegroupC2/m(with similar results). Sr2F2Bi2/3S2features hexagonallayers of alternating [Sr2F2+and [Bi2/3S2-, and the modulated structure arises from the unique ordering pattern of Sr2+cations.SrFPbBiS3, SrFAg0.5Bi1.5S3, and Sr2F2Bi2/3S2are semiconductors with band gaps of 1.31, 1.21, and 1.85 eV, respectively. The lattercompound exhibits room temperature red photoluminescence at similar to 700 nm.