Development of tungsten oxide hydrate phases during precipitation, room temperature ripening and hydrothermal treatment

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Abstract

Morphology and structure transformation of tungstic acid hydrate, H2WO4·nH2O precipitates, have been studied in aqueous phase with various levels of residual [Na+]s at room temperature and at 120 °C in autoclave. Spindle-shaped morphology is characteristic for the washing product of the freshly prepared precipitates. Residual sodium is a persistent contaminant in H2WO4·H2O. Sodium ion content in the solid phase has been found to control reaction route at hydrothermal treatment of tungstic acid hydrates. Morphological changes against [Na+]s content at 120 °C are significant. Rectangular crystallites of WO3·H2O, hexagonal platelets of WO3·1/3H2O or their mixture can develop from the precursor spindle-shaped H2WO4·H2O particles with various [Na+]s at 120 °C. It is noteworthy that particles that ripened at room temperature display faces and axes seemingly corresponding to those of the crystallites developed in the hydrothermal process.

Original languageEnglish
Pages (from-to)353-358
Number of pages6
JournalSolid State Ionics
Volume151
Issue number1-4
DOIs
Publication statusPublished - Nov 1 2002
EventSSP- 2000 - Tokyo, Japan
Duration: Dec 11 2000Dec 13 2000

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Keywords

  • Hydrothermal treatment
  • Morphology
  • Residual sodium
  • Tungsten oxide

ASJC Scopus subject areas

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

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