Structure of Te-rich Te-Ge-X (X = I, Se, Ga) glasses

Pál Jóvári, Ivan Kaban, Bruno Bureau, Allison Wilhelm, Pierre Lucas, Brigitte Beuneu, Dariusz A. Zajac

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34 Scopus citations

Abstract

The structure of glassy Te78Ge11Ga11, Te79Ge16Ga5, Te70Ge 20Se10 and Te73Ge20I 7-promising materials for far infrared applications-was investigated by means of x-ray and neutron diffraction as well as extended x-ray absorption fine structure measurements at various edges. Experimental data sets were fitted simultaneously in the framework of the reverse Monte Carlo simulation technique. Short range order in Te85Ge15 was reinvestigated by fitting a new x-ray diffraction measurement together with available neutron diffraction and extended x-ray absorption fine structure data. It was found that Te85Ge15 consists mostly of GeTe 4 structural units linked together directly or via bridging Te atoms. Te is predominantly twofold coordinated in Te85Ge15, Te70Ge20Se10 and Te73Ge 20I7 while in Te78Ge11Ga 11 and Te79Ge16Ga5 the Te coordination number is significantly higher than 2. The Te-Te bond length is 2.80 ± 0.02 Å in Te78Ge11Ga11 while it is as short as 2.70 ± 0.02 Å and 2.73 ± 0.02 Å in Te73Ge20I7 and Te 70Ge20Se10, respectively. Our results show that the strengths of GeTe4 (GeTe3I, GeTe3Se) 'units' are very similar in all glasses investigated but the connection between these units depends on the third component. Differences in the Te coordination number suggest that unlike Se or I, Ga does not build into the Ge-Te covalent network. Instead, it forms a covalent bond with the non-bonding p electrons of Te, which results in an increase in the average Te coordination number.

Original languageEnglish (US)
Article number404207
JournalJournal of Physics Condensed Matter
Volume22
Issue number40
DOIs
StatePublished - Oct 13 2010

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics

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