Berlin 2012 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 60: Computational Materials Modelling IX - Interfaces and Boundaries

MM 60.2: Vortrag

Donnerstag, 29. März 2012, 17:30–17:45, TC 006

The stability of Bi-Te and Sb-Te layered structures: a first-principles study — •Kirsten Govaerts¹, Marcel H.F. Sluiter², Bart Partoens³, and Dirk Lamoen¹ — ¹EMAT, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium — ²Department of Materials Science and Engineering, 3mE, Delft University of Technology, Mekelweg 2, 2628 CD, Delft, The Netherlands — ³CMT group, Department of Physics, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium

Using an effective one-dimensional cluster expansion in combination with first-principles electronic structure calculations we have studied the energetics and electronic properties of Bi-Te and Sb-Te layered systems. In order to get a fast convergence we used a (pseudo)ternary cluster expansion, which takes into account the formation of Sb or Bi bilayers after relaxation due to a Peierls distortion of the lattice. With this new method, groundstates of Bi-Te and Sb-Te can be found without making the dataset of ab initio calculated structures unreasonably large. For a Te concentration between 0 and 60 at.% an almost continuous series of (meta)stable structures is obtained consisting of consecutive X bilayers next to consecutive X₂Te₃ units, with X corresponding to Bi or Sb. Our calculations (at T = 0 K) do not show evidence for the existence of separate single phase regions. Metastable compounds with a Te concentration between 0 and 40 at.% are semimetallic, whereas compounds (X₂)_n(X₂Te₃)_m (n,m=1,2,...) with a Te concentration between 50 and 60 at.% are semiconducting. Compounds with an odd number of consecutive X layers are metallic.