Sol-gel synthesis of Bi₂WO₆ powders.

Addition of water to a solution of [Bi₂W]1 in methoxyethanol gave a precipitate. Volatiles were removed in vacuo and the powder was heated as shown below.

Thermal processing of Bi₂WO₆ powder.

After each heating stage, samples were analysed by IR spectroscopy and by X-ray diffraction.

IR spectra of samples after various stages of heating.

X-ray diffractograms of powder samples.

The IR spectra show that organic residues from OR groups are lost by 300 ^oC.

XRD analysis of the powders shows the formation of the orthorhombic phase between 400 and 500 ^oC and of the monoclinic phase at above 700 ^oC.