Hexagonal tungsten bronze synthesized from potassium peroxo-polytungstate and its electrical properties

Isao Tsuyumoto, Akira Kishimoto, Tetsuichi Kudo

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

Peroxo-polytungstic acid, formed by the direct reaction of metallic tungsten with hydrogen peroxide, precipitated an amorphous salt with potassium bromide. Decomposing the precipitate at 400-800°C in air yielded white hexagonal potassium tungstate, KxWO3+ x 2 (x=0.3), with lattice parameters of a=7.31 and c=7.65 Å. On the other hand, thermal decomposition in a reducing atmosphere (H2/H2O) at 500°C gave dark blue hexagonal tungsten bronze (HTB), KxWO3, with a=7.38 and c=7.52 Å, which were almost identical to those reported for HTB. It was found that the redox reaction between tungstate and HTB was completely reversible. A porous pellet of the present HTB showed metallic conductivity (≈10 S/cm, at 25°C) under dry conditions. In a wet atmosphere with only slight humidity, however, its conductivity was dramatically reduced. The conductivity was recovered by treating it again in a dry condition.

Original languageEnglish
Pages (from-to)211-216
Number of pages6
JournalSolid State Ionics
Volume59
Issue number3-4
DOIs
Publication statusPublished - Feb 1993
Externally publishedYes

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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