STRUCTURE REFINEMENT OF TRICLINIC TUNGSTEN TRIOXIDE

The thermodynamically stable form of WO3 at room temperature is triclinic. The structure of this form of WO3 was for the first time refined from neutron diffraction data. The data were obtained on a new high resolution powder diffractometer. The structure obtained appears to be somewhat more accurate than that obtained from single crystal X-ray diffraction data. Rietveld approach was used to refine the neutron powder diffraction data. Results using the software packages GSAS, Rietan and PROFIL are compared. Using GSAS, an R(wp) of 7.97 and an R(p) of 5.87 were obtained. Neutron diffraction data were also collected and analysed on a sample which was a mixture of the monoclinic and triclinic forms of WO3; Rietveld refinements of this data were stable and yielded reasonable results.