Structure of semiconducting versus fast-ion conducting glasses in the Ag–Ge–Se system

Anita Zeidler, Philip Salmon, Dean Whittaker, Andrea Piarristeguy, Annie Pradel, Henry Fischer, Chris J Benmore, Ozgur Gulbiten

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4 Citations (Scopus)

Abstract

The transition from a semiconductor to a fast-ion conductor
with increasing silver content along the Agx(Ge0.25Se0.75)(100−x)
tie line (0 ≤ x ≤ 25) was investigated on multiple length scales
by employing a combination of electric force microscopy,
X-ray diffraction, and neutron diffraction. The microscopy
results show separation into silver-rich and silver-poor phases,
where the Ag-rich phase percolates at the onset of fastion
conductivity. The method of neutron diffraction with
Ag isotope substitution was applied to the x=5 and x=25
compositions, and the results indicate an evolution in structure
of the Ag-rich phase with change of composition. The Ag–Se
nearest-neighbours are distributed about a distance of 2.64(1)
Å, and the Ag–Se coordination number increases from 2.6(3)
at x=5 to 3.3(2) at x=25. For x=25, the measured Ag–Ag
partial pair-distribution function gives 1.9(2) Ag–Ag nearestneighbours
at a distance of 3.02(2) Å. The results show breakage
of Se–Se homopolar bonds as silver is added to the Ge0.25Se0.75
base glass, and the limit of glass-formation at x28 coincides
with an elimination of these bonds. A model is proposed for
tracking the breakage of Se–Se homopolar bonds as silver is
added to the base glass.
Original languageEnglish
Article number171401
Pages (from-to)1-21
Number of pages21
JournalRoyal Society Open Science
Volume5
Issue number1
DOIs
Publication statusPublished - 17 Jan 2018

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Keywords

  • glass structure
  • phase separation
  • super-ionic phase
  • percolation transition
  • electric force microscopy
  • neutron diffraction
  • x-ray diffraction

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