title: Synthesis, Crystal Structure, and Photoelectric Properties of a New Layered Bismuth Oxysulfide.
abstract: [Bi2O2]-containing tetragonal compounds have received enormous attention due to unique functions including ferroelectricity, photocatalysis, and superconductivity. Here, a new layered compound Bi9O7.5S6 was synthesized via a facile hydrothermal route. The compound, belonging to a new structure type crystallizes in a rhombohedral system with space group R3̅m (a = 4.0685(1) Å, c = 31.029(5) Å, V = 444.8(1) Å(3), Z = 1). The overall crystal structure consists of alternatively packed unique [Bi2O2] and [BiS2] layers along [001] which are combined with each other by van der Waals interaction. The phase purity of the product is confirmed by powder X-ray diffraction. XPS analyses indicate +3 for Bi and -2 for S atoms. The temperature dependence of resistivity ρ(T) indicates that the semiconducting sample follows the mechanisms of variable range hopping (VRH) and adiabatic small polaron hopping (SPH). The direct-transition band gap, Eg = 1.27 eV derived from optical absorption spectrum, falls in the optimal region of solar absorber materials. Accordingly, the photoelectric measurement demonstrates the potential for applications for photovoltaic devices.
authors.affiliation: †CAS Key Laboratory of Materials for Energy Conversion and State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China.
authors.forename: Sha
authors.initials: S
authors.lastname: Meng
authors.affiliation: †CAS Key Laboratory of Materials for Energy Conversion and State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China.|§State Key Laboratory of Rare Earth Materials Chemistry and Applications and National Laboratory of Molecular Science, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, People's Republic of China.
authors.forename: Xian
authors.initials: X
authors.lastname: Zhang
authors.affiliation: †CAS Key Laboratory of Materials for Energy Conversion and State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China.
authors.forename: Ganghua
authors.initials: G
authors.lastname: Zhang
authors.affiliation: †CAS Key Laboratory of Materials for Energy Conversion and State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China.
authors.forename: Yaoming
authors.initials: Y
authors.lastname: Wang
authors.affiliation: †CAS Key Laboratory of Materials for Energy Conversion and State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China.
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.affiliation: †CAS Key Laboratory of Materials for Energy Conversion and State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China.|§State Key Laboratory of Rare Earth Materials Chemistry and Applications and National Laboratory of Molecular Science, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, People's Republic of China.
authors.forename: Fuqiang
authors.initials: F
authors.lastname: Huang