A Layered Tin Bismuth Selenide with Three Different Building Blocks that Account for an Extremely Large Lattice Parameter of 283 Å. Issue 47 (27th July 2020)

• Record Type: Journal Article
• Authors: Nentwig, Markus; Eisenburger, Lucien; Heinke, Frank; Souchay, Daniel; Oeckler, Oliver
• Is Part Of: Chemistry. Volume 26:Issue 47(2020)
• Page Start: 10676
• Page End: 10681
• Publication Date: 2020-07-27
• Subjects: bismuth -- layered compounds -- long-periodic crystal structure -- selenium -- tin; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202000663
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: The layered compound Sn2.8(4) Bi20.2(4) Se27 exhibits an extraordinarily long‐periodic 150 R stacking sequence. The crystal structure contains three different building blocks, which form upon the addition of Sn to a Bi‐rich bismuth selenide. Sn‐doped Bi2 double ("2") layers similar to those in elemental bismuth, Sn0.3 Bi1.7 Se3 quintuple ("5") layers and Sn0.4 Bi2.6 Se4 septuple ("7") layers are arranged in a 7525757525|7525757525|7525757525 sequence, which corresponds to a structure with a= 4.1819(4) and c= 282.64(6) Å in space group R 3 ‾ m. The structure of a microcrystal was determined using microfocused synchrotron radiation and refined as a formally commensurately modulated structure in (3+1)D superspace (superspace group R 3 ‾ m(00 γ )00), with a trivial basic structure that contains just one atom. The stacking sequence as well as the cation distribution are confirmed by aberration‐corrected scanning transmission electron microscopy (STEM) in combination with chemical mapping by X‐ray spectroscopy with atomic resolution. Stacking faults are not typical but have been observed occasionally. Abstract : Layering up : 150 R ‐Sn2.8(4) Bi20.2(4) Se27 exhibits an extraordinarily long‐periodic layered structure with a lattice parameter of c= 282.6(6) Å. The structure is built up from three different kinds of slabs, that is, double, quintuple and septuple layers, which has been confirmed by STEM‐HAADF and EDX with atomic resolution.