Partial thermal reduction of ammonium paratungstate tetrahydrate: Evolved gas analysis (TG/DTA-MS) and solid state studies (XRD, FTIR)

I. M. Szilágyi, J. Madarász, F. Hange, G. Pokol

Research output: Article

26 Citations (Scopus)

Abstract

Thermal decomposition of ammonium paratungstate tetrahydrate, (NH 4)10[H2W12O42] •4H2O has been followed by simultaneous TG/DTA and online evolved gas analysis (TG/DTA-MS) in flowing 10% H2/Ar directly up to 900°C. Solid intermediate products have been structurally evaluated by FTIR spectroscopy and powder X-ray diffraction (XRD). A previously unexplained exothermic heat effect has been detected at 700-750°C. On the basis of TG/DTA as well as H2O and NH3 evolution curves and XRD patterns, it has been assigned to the formation and crystallization heat of γ-tungsten-oxide (WO2.72/W18O49) from β-tungsten-oxide (WO2.9/W20O58) and residual ammonium tungsten bronze.

Original languageEnglish
Pages (from-to)139-144
Number of pages6
JournalJournal of Thermal Analysis and Calorimetry
Volume88
Issue number1
DOIs
Publication statusPublished - ápr. 1 2007

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

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