The thermal decomposition of ammonium paratungstate

The thermal decomposition of monoclinic, orthorhombic and freeze-dried ammonium paratungstate (APT) has been studied over the temperature range 100 to 500°C using thermogravimetry, evolved gas analysis. X-ray diffraction and electron optical techniques. The particle morphologies of the original APT have been related to the morphologies of the products of decomposition. A mechanism of decomposition which postulates the formation and subsequent decomposition of amorphous ammonium metatungstate is proposed and substantiated by X-ray diffraction analysis and evolved gas analysis.