Published online by Cambridge University Press: 05 March 2012
Data for the standard material NBS SRM 674, TiO2, were collected on two diffractometers: a) a Philips PW 1050/37 standard diffractometer of the Bragg-Brentano type equipped with a post diffraction curved Ge monochromator, b) a Stoe Stadi P diffractometer of transmission type equipped with a curved incident beam Ge monochromator. Both monochromators were set to select pure CuKα1 radiation. The reflection type instrument gives a much larger peak to background ratio than the transmission instrument, for which the background is much higher than with the reflection instrument. Rietveld refinements were carried out on both data sets with the programs DBWS-9807 and general structure analysis system (GSAS). The structural parameter of the oxygen atom of rutile depends neither on data set nor program, whereas, e.g., thermal displacement parameters seem to depend on both data set and program.