Synthesis, crystal structure and optical properties of K2Cu2GeS4

• Published in: Journal of alloys and compounds 2017-11, Vol.725, p.557-562
• Main Authors: Sun, Baohua, He, Jianqiao, Zhang, Xian, Bu, Kejun, Zheng, Chong, Huang, Fuqiang
• Format: Article
• Language: English
• Subjects: Absorption spectra; Band gap; Copper; Crystal defects; Crystal structure; Intermediate band; Layered structure; Optical properties; Photoelectricity; Potassium compounds; Quaternary thiogermanate; Semiconductor; Thioureas; X-ray diffraction
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2017.07.187

A new compound K2Cu2GeS4 was successfully synthesized by using molten thiourea reactive flux method. The structure was determined by single crystal X-ray diffraction. The compound crystallizes in the monoclinic system of space group P2/c with a unit cell of a = 7.063 (3) Å, b = 5.435 (3) Å, c = 11.037 (6) Å and β = 112.83 (3)°. The crystal structure of K2Cu2GeS4 is composed of defective anti-PbO like [Cu2GeS4]2− layers which are interleaved by K+ cations. This compound is a semiconductor with an indirect band gap of 2.3 (1) eV, which is derived from optical absorption spectrum. First principles calculations reveal that K2Cu2GeS4 has interesting intermediate bands consisting of Ge-4s and S-3p orbitals. This new semiconductor is potentially suitable for solar photocatalytic and photoelectric applications. •A new layered compound of K2Cu2GeS4 were successfully synthesized via molten thiourea reactive flux method.•The crystal structure is composed of defective anti-PbO like [Cu2GeS4]2- layers which are interleaved by K+ cations.•This compound is a semiconductor with a band gap of 2.3 eV.•This compound is an indirect band gap semiconductor with interesting intermediate band consisting of Ge 4s and S 3p.