New Quaternary Barium Copper/Silver Selenostannates: Different Coordination Spheres, Metal-Metal Interactions, and Physical Properties
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- 作者：Abdeljalil Assoud ; Navid Soheilnia ; and Holger Kleinke
- 刊名：Chemistry of Materials
- 出版年：2005
- 出版时间：May 3, 2005
- 年：2005
- 卷：17
- 期：9
- 页码：2255 - 2261
- 全文大小：376K
- 年卷期：v.17,no.9(May 3, 2005)
- ISSN：1520-5002
文摘
BaAg2SnSe4, BaCu2SnSe4, and Ba3Cu2Sn3Se10 were prepared by directly reacting the elements instoichiometric ratios at 800 
C, followed by long heating between 600 and 650 C. BaAg2SnSe4 crystallizesin the BaAg2SnS4 type, space group I222, BaCu2SnSe4 in the SrCu2GeSe4 type, space group Ama2, andBa3Cu2Sn3Se10 in a new structure type, space group P21/n. All three structures comprise almost undistortedSnSe4 tetrahedra and pairs of the group 11 elements (M = Cu and Ag). While both the M atoms arebonded to four Se atoms in each case, the deviations from an MSe4 tetrahedron are severe, and distinctlydifferent within this series. BaAg2SnSe4, BaCu2SnSe4, and Ba3Cu2Sn3Se10 are black semiconductors, withcomputed band gaps of 0.2, 0.7, and 1.2 eV, respectively. The experimental gaps for the former two are0.24 and 0.48 eV, respectively. The electrical conductivities consistently decrease with increasing bandgap.
C, followed by long heating between 600 and 650 C. BaAg2SnSe4 crystallizesin the BaAg2SnS4 type, space group I222, BaCu2SnSe4 in the SrCu2GeSe4 type, space group Ama2, andBa3Cu2Sn3Se10 in a new structure type, space group P21/n. All three structures comprise almost undistortedSnSe4 tetrahedra and pairs of the group 11 elements (M = Cu and Ag). While both the M atoms arebonded to four Se atoms in each case, the deviations from an MSe4 tetrahedron are severe, and distinctlydifferent within this series. BaAg2SnSe4, BaCu2SnSe4, and Ba3Cu2Sn3Se10 are black semiconductors, withcomputed band gaps of 0.2, 0.7, and 1.2 eV, respectively. The experimental gaps for the former two are0.24 and 0.48 eV, respectively. The electrical conductivities consistently decrease with increasing bandgap.