X-RAY-DIFFRACTION ANALYSIS

X-ray diffraction analyses were carried out by nine laboratories. The equipment and experimental conditions of analysis were generally different. However, the results obtained were very similar and coherent. Samples with a high vanadium content showed exclusively the presence of TiO2 (anatase) and crystallites of V2O5 as long as not pretreated. No TiO2 (rutile) or other vanadium oxide was observed. V2O5 was also observed in low vanadium content samples in two analyses. No other crystalline phases could be observed, although the presence of very weak lines were detected. These lines were not identified as vanadium oxide, titanium oxide or vanadium-titanium oxide. In the pretreated samples containing vanadium, the presence of V2O5 lowered the temperature of the phase transition of anatase to rutile.