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 2002

Fingerprint

tungsten oxides
spindles
Hydrates
Crystallites
hydrates
crystallites
Tungsten
Precipitates
precipitates
Sodium
sodium
reaction control
acids
autoclaves
Oxides
Acids
washing
Autoclaves
room temperature
Platelets

Keywords

  • Hydrothermal treatment
  • Morphology
  • Residual sodium
  • Tungsten oxide

ASJC Scopus subject areas

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

Cite this

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title = "Development of tungsten oxide hydrate phases during precipitation, room temperature ripening and hydrothermal treatment",
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.",
keywords = "Hydrothermal treatment, Morphology, Residual sodium, Tungsten oxide",
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pages = "353--358",
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TY - JOUR

T1 - Development of tungsten oxide hydrate phases during precipitation, room temperature ripening and hydrothermal treatment

AU - Balázsi, C.

AU - Pfeifer, J.

PY - 2002/11

Y1 - 2002/11

N2 - 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.

AB - 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.

KW - Hydrothermal treatment

KW - Morphology

KW - Residual sodium

KW - Tungsten oxide

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U2 - 10.1016/S0167-2738(02)00539-8

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EP - 358

JO - Solid State Ionics

JF - Solid State Ionics

SN - 0167-2738

IS - 1-4

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