Morphological and kinetic studies on hexagonal tungstates

Alexej Michailovski, Ragnar Kiebach, Wolfgang Bensch, Jan Dierk Grunwaldt, Alfons Baiker, Sridhar Komarneni, Greta R. Patzke

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Formation of nanostructured hexagonal alkali tungstates (HTBs) from ammonium metatungstate (AMT) and alkali chlorides has been investigated by a combined strategy encompassing in situ spectroscopic techniques and hydrothermal synthetic studies. They demonstrate how the morphology of the HTBs can be tuned by the straightforward hydrothermal reaction of ammonium metatungstate with the choice of appropriate alkali chlorides. The resulting particle shapes vary from highly anisotropic fibers to multilevel assemblies of hierarchically grown nanorods. Microwave-hydrothermal techniques have further expanded this morphological spectrum. Next, the growth process of alkali HTBs was explored for selected cases by combination of in situ EXAFS and EDXRD investigations. They both show that nucleation starts after a certain induction time and is strongly dependent on the concentration. Though the individual kinetics of alkali HTB formation differ slightly from each other, all alkali cations have a nucleation-controlled growth mechanism in common.

Original languageEnglish (US)
Pages (from-to)185-197
Number of pages13
JournalChemistry of Materials
Issue number2
StatePublished - Jan 23 2007

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • General Chemical Engineering
  • Materials Chemistry


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