Mixed-valent selenium compounds: Noncentrosymmetric Cd3(SeO3)2(SeO4) and Hg3(SeO3)2(SeO4) and centrosymmetric Pb2(SeO3) (SeO4)
Abstract
Three mixed-valent selenium compounds: Cd3(SeO3)2(SeO4), Hg3(SeO3)2(SeO4) and Pb2(SeO3) (SeO4) were successfully synthesized by hydrothermal methods. Among these three compounds, Cd3(SeO3)2(SeO4) and Hg3(SeO3)2(SeO4) are isostructural and crystalize in the noncentrosymmetric (NCS) polar space group P21. Powder second-harmonic generation (SHG) measurements using 1064 nm radiation indicate that Cd3(SeO3)2(SeO4) and Hg3(SeO3)2(SeO4) exhibit SHG intensities of approximately 0.6 and 0.8 times of KH2PO4 (KDP), respectively. Pb2(SeO3) (SeO4) is centrosymmetric (CS) and crystalizes in the space group Pnma. Pb2(SeO3) (SeO4) exhibits a 3D framework composed of chains of edge-sharing [PbO6] octahedra linked to [SeO3] and [SeO4] groups. M3(SeO3)2(SeO4) (M = Cd, Hg) also exhibits a 3D structure consisting of layers of [MO8], [MO6] and [SeO3] polyhedra connected by [SeO4] groups. For all of the reported compounds, infrared spectroscopy, UV-vis diffuse reflectance spectroscopy and thermogravimetric measurements were performed.
- Publication:
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Journal of Solid State Chemistry France
- Pub Date:
- June 2020
- DOI:
- 10.1016/j.jssc.2020.121292
- Bibcode:
- 2020JSSCh.28621292S
- Keywords:
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- Mixed-valent selenium compounds;
- Hydrothermal methods;
- SHG;
- Crystal structures