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Cation Size Effect on the Framework Structures in ABi2SeO3F5(A= K and Rb): first examples of alkali metal bismuth selenite fluorides

Abstract

Two new centric alkali metal bismuth selenite fluorides, ABi2SeO3F5 (A= K and Rb), have been synthesized through a soft hydrothermal method. KBi2SeO3F5 crystallizes in an orthorhombic crystal system with the centric space group Pbcm possessing a three-dimensional (3D) network made up of SeO3 trigonal pyramids and asymmetric BiO3F5 polyhedra. As regards compound RbBi2SeO3F5, it crystallizes in a triclinic crystal system with a centric space group of P-1, which contains alternant two-dimensional (2D) [Bi2SeO3F5]∞1- layers seperated by Rb+ cations. In terms of structure, the differences between KBi2SeO3F5 and RbBi2SeO3F5 originate from the size of alkali metal cations, which has a great influence on the framework geometry and the dimensionalities of crystals. The UV-vis diffuse reflectance spectroscopy study of powder samples indicates that the band gaps for KBi2SeO3F5 and RbBi2SeO3F5 are approximately 4.08 and 4.18 eV respectively, which are largest ones among known bismuth selenites owing to the existence of alkali metal cations as well as fluorine anions in crystal. Furthermore, theoretic calculation shows that the optical absorption of two compounds are mainly attributable to the contribution of BiOxFy polyhedra and [SeO3]2- anionic groups.

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Publication details

The article was received on 02 Feb 2018, accepted on 11 Apr 2018 and first published on 16 Apr 2018


Article type: Paper
DOI: 10.1039/C8DT00450A
Citation: Dalton Trans., 2018, Accepted Manuscript
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    Cation Size Effect on the Framework Structures in ABi2SeO3F5(A= K and Rb): first examples of alkali metal bismuth selenite fluorides

    S. Shi, M. Luo, C. Lin and N. Ye, Dalton Trans., 2018, Accepted Manuscript , DOI: 10.1039/C8DT00450A

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