An EXAFS Study of Coordination of Ag in AgI-Ag<sub>2</sub>O-GeO<sub>2</sub> Glasses

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  • MORIKAWA Hideki
    Research Laboratory of Engineering Materials, Tokyo Institute of Technology
  • OSUKA Takuo
    Research Laboratory of Engineering Materials, Tokyo Institute of Technology Asahi Glass Co., Ltd.
  • YIN Cheng Dong
    Research Laboratory of Engineering Materials, Tokyo Institute of Technology Qinhuangdao Glass Research Institute, P. R. C.
  • OKUNO Masayuki
    Research Laboratory of Engineering Materials, Tokyo Institute of Technology
  • MARUMO Fumiyuki
    Research Laboratory of Engineering Materials, Tokyo Institute of Technology

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Other Title
  • EXAFS解析によるAgI-Ag<sub>2</sub>O-GeO<sub>2</sub>系ガラス中のAgの配位
  • EXAFS カイセキ ニ ヨル AgI Ag2O GeO2ケイ ガラスチュウ

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Abstract

Local structures around Ag+ ions in ion-conducting glasses in the system AgI-Ag2O-GeO2 were investigated by Ag K EXAFS (extended X-ray absorption fine structure) analysis. By using Ag2O and AgI crystals as reference samples, average Ag-O and Ag-I distances for three kinds of glass samples were estimated from |F(r)| curves to be 2.15-2.22Å and 2.74-2.87Å, respectively. The Ag-O atomic distances suggest that a part of Ag+ ions locate near the polygermanate anions which consisted of GeO4 tetrahedra. As the Ag+ ions of this type are strongly bonded to O2- ions, they do not contribute to the ionic conduction. It was also concluded on the basis of the Ag-I atomic distances that the rest of Ag+ ions locate at tetrahedral sites surrounded by four I- ions. Since the coodinations of these Ag+ ions are similar to those of Ag+ ions in AgI crystals which show ionic conductivity, the Ag+ ions of this type contribute to the ionic conduction.

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