Several techniques have been used to study the structure of the Keggin-type polyoxometalate salt ammonium metatungstate(AMT)—(NH4)6[H2W12O40]*nH2O, a potential fuel cell catalyst. The dehydrated salt is comprised of a mixture of crystallites of different unit cells in a centered eutactic cubic configuration, with an average unit cell of a≅12.295. Varied orientations of the Keggin ions in the cubic arrangement create the differences, and orientational variation within each unit cell size represents an energy well.

The thermal decomposition of ammoniu metatungstate(AMT)involved several steps in inert atmosphere: (i)That is release of crystal water between 25°C and 200°C resulte in dehydrated AMT. (ii) The formation of an amorphous phase between 200°C and 380 °C.

Using a coupling process of neutralization–nanofiltration–crystallization, pure  is producted . The effects of chemical neutralization of ammonium paratungstate (APT) by nitric acid, operating pressure, the concentration of AMT and the volume of washing water on the coupling process were systematically discussed. It was found that the better conditions of AMT

The structure of ammonium metatungstate powder is highly dependent on hydration and POM molecule rotation, with cation and hydrogen  bonding  forces directing  a  mixture  of structure that have been studied with bulk and single-crystal  methods.   The illustration show simulated anion structural disorder that the fully dehydrated form of the  compound.

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