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 - 1993
Externally publishedYes

Fingerprint

Tungsten
Bronze
bronzes
Potassium
potassium
tungsten
Electric properties
electrical properties
tungstates
conductivity
potassium bromides
atmospheres
Redox reactions
hydrogen peroxide
pellets
Hydrogen peroxide
Hydrogen Peroxide
Lattice constants
thermal decomposition
humidity

ASJC Scopus subject areas

  • Electrochemistry
  • Physical and Theoretical Chemistry
  • Energy Engineering and Power Technology
  • Materials Chemistry
  • Condensed Matter Physics

Cite this

Hexagonal tungsten bronze synthesized from potassium peroxo-polytungstate and its electrical properties. / Tsuyumoto, Isao; Kishimoto, Akira; Kudo, Tetsuichi.

In: Solid State Ionics, Vol. 59, No. 3-4, 1993, p. 211-216.

Research output: Contribution to journalArticle

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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 {\AA}. 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 {\AA}, 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.",
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N2 - 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.

AB - 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.

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