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Title: Crystal structure, electronic structure and physical properties of the new low-valent thallium silicon telluride Tl{sub 6}Si{sub 2}Te{sub 6} in comparison to Tl{sub 6}Ge{sub 2}Te{sub 6}

The title compounds were prepared from the elements in the stoichiometric ratio at 800deg. C under exclusion of air. Tl{sub 6}Si{sub 2}Te{sub 6} crystallizes in the space group P1-bar , isostructural with Tl{sub 6}Ge{sub 2}Te{sub 6}, with a=9.4235(6)A, b=9.6606(7)A, c=10.3889(7)A, {alpha}=89.158(2){sup o}, {beta}=96.544(2){sup o}, {gamma}=100.685(2){sup o}, V=923.3(1)A{sup 3} (Z=2). Its structure is composed of dimeric [Si{sub 2}Te{sub 6}]{sup 6-} units with a Si-Si single bond, while the Tl atoms are irregularly coordinated by five to six Te atoms. Numerous weakly bonding Tl-Tl contacts exist. Both title compounds are black semiconductors with small band gaps, calculated to be 0.9eV for Tl{sub 6}Si{sub 2}Te{sub 6} and 0.5eV for Tl{sub 6}Ge{sub 2}Te{sub 6}. The Seebeck coefficients are +65{mu}VK{sup -1} in case of Tl{sub 6}Si{sub 2}Te{sub 6} and +150{mu}VK{sup -1} in case of Tl{sub 6}Ge{sub 2}Te{sub 6} at 300K, and the electrical conductivities are 5.5 and 3{omega}{sup -1}cm{sup -1}, respectively.
Authors:
 [1] ;  [1] ;  [2]
  1. Department of Chemistry, University of Waterloo, Waterloo, Ont., N2L 3G1 (Canada)
  2. Department of Chemistry, University of Waterloo, Waterloo, Ont., N2L 3G1 (Canada). E-mail: kleinke@uwaterloo.ca
Publication Date:
OSTI Identifier:
20905427
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 179; Journal Issue: 8; Other Information: DOI: 10.1016/j.jssc.2006.05.029; PII: S0022-4596(06)00317-3; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; COMPARATIVE EVALUATIONS; ELECTRIC CONDUCTIVITY; ELECTRONIC STRUCTURE; SEMICONDUCTOR MATERIALS; SILICIDES; SPACE GROUPS; THALLIUM TELLURIDES; TRICLINIC LATTICES