X-ray diffraction study of microstructure of amorphous tungsten trioxide films prepared by electron beam vacuum evaporation

Microstructure of a-WO₃ films prepared by electron beam vacuum evaporation was examined based on XRD. The peak positions in the observed PDFs corresponded with those in the PDFs calculated from the crystal structure of hexagonal WO₃ and WO₃ · 1 3H₂O, and the framework structure of the films was therefore thought to consist of the basic structure of these crystals, three-, four-, and six-membered rings formed by WO₆ octahedra. Microcluster models in which the atomic arrangement was similar to that of hexagonal WO₃ were assumed and investigated in detail. The pair distribution functions calculated from these models showed good agreement with the observed values, and the structure of a-WO₃ films was consequently suggested to consist of clusters in which the octahedra were arranged in the same manner as those in hexagonal WO₃.