Extended homologous series of Sn–O layered systems: A first-principles study.

Apart from the most studied tin-oxide compounds, SnO and SnO 2 , intermediate states have been claimed to exist for more than a hundred years. In addition to the known homologous series (Seko et al., 2008 [27]), we here predict the existence of several new compounds with an O concentration between 50% (SnO) and 67% (SnO 2 ). All these intermediate compounds are constructed from removing one or more (101) oxygen layers of SnO 2 . Since the van der Waals (vdW) interaction is known to be important for the Sn–Sn interlayer distances, we use a vdW-corrected functional, and compare these results with results obtained with PBE and hybrid functionals. We present the electronic properties of the intermediate structures and we observe a decrease of the band gap when (i) the O concentration increases and (ii) more SnO-like units are present for a given concentration. The contribution of the different atoms to the valence and conduction band is also investigated. [ABSTRACT FROM AUTHOR]