Dependence of structural data from sinθ/λ extension in Rietveld refinement of virtually texture-free laboratory X-ray powder diffraction data

Abstract

Present work analyses the effects of reducing the resolution of a data set on the structural parameters of three compounds, namely nitratine NaNO 3 , gypsum CaSO 4 · 2H 2 O, and K-alum KAl(SO 4 ) 2 · 12H 2 O, characterized by an increasing degree of structural complexity. The unexpected result is that in the case of the nearly absence of preferred orientation adequate structural information can be retrieved from data sets extending up to a minimum sinq/l values of ca . 0.4, corresponding to a 2q value of ca . 75° for CuKa radiation, at least in the case of compounds characterized by fairly moderate complexity ( ca . 25 structural parameters). Therefore, in the case of experiments collected in step-scan mode, whenever time is a limiting factor, an increase of the peak/background ratio results more advantageous than the extension of the explored reciprocal lattice.