Imaging of the crystal structure of a new WO₃, phase by high-resolution electron microscopy

A new hydrate of tungsten trioxide with the formula WO3,1/3 H2O was found by hydrothermal treatment in an autoclave either of crystalline WO3,2 H2O or of a tungstic acid gel. By dehydration of this hydrate in the air and by subsequent reductions a set of new compounds of tungsten were obtained : a polymorph of WO3 and two other oxides, all unknown. Their structures have in general a higher symmetry than the compounds already known. The detailed procedure for preparing these phases, their analysis, their structures and properties will be reported elsewhere (1).In the present paper, we examine the structure of the new polymorph of WO3. This compound is white. A study by powder X-ray diffraction shows that this compound is hexagonal with the space group P6/mmm and the lattice parameters a = 7.296 and c = 3.899 A°. The structure, which can be imagined by analogy with the hexagonal bronze structures (2), is shown in figure 1.</jats:p