Abstract
The layered compound Sn2.8(4)Bi20.2(4)Se27 exhibits an extraordinarily long‐periodic 150R 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, Sn0.3Bi1.7Se3 quintuple (“5”) layers and Sn0.4Bi2.6Se4 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(00γ)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.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
