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

The transition from a semiconductor to a fast-ion conductor with increasing silver content along the Ag x(Ge 0.25Se 0.75) (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 fast-ion 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 nearest-neighbours at a distance of 3.02(2) Å. The results show breakage of Se–Se homopolar bonds as silver is added to the Ge 0.25Se 0.75 base glass, and the limit of glass-formation at x≃28 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.
Authors:
ORCiD logo [1] ; ORCiD logo [1] ; ORCiD logo [1] ; ORCiD logo [2] ; ORCiD logo [2] ; ORCiD logo [3] ; ORCiD logo [4] ; ORCiD logo [5]
  1. Univ. of Bath (United Kingdom). Dept. of Physics
  2. Univ. of Montpellier (France). Inst. Charles Gerhardt
  3. Inst. Laue Langevin, Grenoble (France)
  4. Argonne National Lab. (ANL), Argonne, IL (United States). X-ray Science Division. Advanced Photon Source
  5. Corning Incorporated, Corning, NY (United States). Science and Technology Division
Publication Date:
Grant/Contract Number:
AC02-06CH11357; EP/G008795/1; EP/J009741/1
Type:
Accepted Manuscript
Journal Name:
Royal Society Open Science
Additional Journal Information:
Journal Volume: 5; Journal Issue: 1; Journal ID: ISSN 2054-5703
Publisher:
The Royal Society Publishing
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States); Univ. of Bath (United Kingdom)
Sponsoring Org:
USDOE; Engineering and Physical Sciences Research Council (EPSRC)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; glass structure; phase separation; super-ionic phase; percolation transition; electric force microscopy; neutron and X-ray diffraction
OSTI Identifier:
1461314