Compositional dependence of the proton conductivity of anodic ZrO 2-WO3-SiO2 nanofilms at intermediate temperatures

Ke Ye, Yoshitaka Aoki, Etsushi Tsuji, Shinji Nagata, Hiroki Habazaki

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

Novel proton-conducting ZrO2-WO3-SiO2 nanofilms of various compositions and thicknesses (∼50 to ∼300 nm) have been prepared by anodizing of magnetron-sputtered Zr-W-Si alloys in 0.1 mol dm-3 phosphoric acid electrolyte at 20°C. All the anodic oxide nanofilms examined reveal efficient proton conductivity after post-annealing at 250°C. Further increase in the post-annealing temperature results in the conductivity degradation for the anodic oxide nanofilms on the alloy containing only 5 at% silicon, while the high conductivity is maintained even after post-annealing at 300°C for those containing 15 at% or more silicon. The proton conductivity is dependent upon tungsten content; the conductivity of 5 × 10-6 S cm-1 for the ∼100 nm-thick films on the Zr31W55Si14 at 100°C is approximately 10 times that on the Zr48W37Si15. The anodic oxide nanofilms consist of two layers, comprising a thin outer ZrO2 layer and an inner ZrO2-WO3-SiO2 layer. Both layers show thickness-dependent conductivity and the proton conductivity of the two-layer anodic films is enhanced one order of magnitude by reducing the film thickness from ∼300 nm to ∼100 nm. Different mechanisms are proposed for the thickness dependence of the conductivity of the outer and inner layers.

Original languageEnglish
Pages (from-to)F1096-F1102
JournalJournal of the Electrochemical Society
Volume160
Issue number9
DOIs
Publication statusPublished - 2013 Aug 20

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films
  • Electrochemistry
  • Materials Chemistry

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