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Crystal and electronic structure of the red semiconductor Ba4LaSbGe3Se13comprising the complex anion [Ge2Se7–Sb2Se4–Ge2Se7]14−

Authors
Journal
Journal of Solid State Chemistry
0022-4596
Publisher
Elsevier
Publication Date
Volume
177
Issue
7
Identifiers
DOI: 10.1016/j.jssc.2004.03.008
Keywords
  • Crystal Structure
  • Electronic Structure
  • Semiconductor
  • Germanium
  • Antimony
  • Selenium

Abstract

Abstract Ba 4LaGe 3SbSe 13 was prepared by reacting the elements under exclusion of air at 700°C, followed by slow cooling to room temperature. It crystallizes in a new type of the monoclinic space group P2 1/ c, with lattice dimensions of a=1633.30(9) pm, b=1251.15(7) pm, c=1303.21(7) pm, β=103.457(2)°, V=2590.0(2) 10 6 pm 3 ( Z=4). The structure contains isolated GeSe 4 as well as Ge 2Se 7 digermanate units. Two of the latter are interconnected via an Sb 2Se 4 bridge yielding an almost linear complex anion [Ge 2Se 7–Sb 2Se 4–Ge 2Se 7] 14−. The oxidation states are assigned to be Ba II, La III, Ge IV, Sb III, and Se −II, in accord with an electronically saturated nonmetal. The lone pair of Sb III reflects itself in highly irregular Se coordination. The red color of the material is indicative of semiconducting behavior with an activation energy of 2.0 eV. Electronic structure calculations based on the LMTO approximation point to a smaller gap, typical for this calculation method. We utilized the COHP tool to explore the bonding character of the different Sb–Se interactions.

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