XRD Profile Analysis of Clay Minerals

摘要

XRD profile analysis of smectites is usually limited to the apparent d-spacing estimated from the peak maxima from the raw data. This can lead to the wrong d-spacing and consequently to the wrong conclusions about mixed layering (interstratification) and wrong structural model of interlayer. The interference function is modulated by the angle dependent instrumental factors (Lorentz-polarization, diffraction geometry) and physical factors (structural factor, volume absorption, surface roughness absorption) which lead to profile distortions and to the shift of the peak maxima. This effect is especially significant at low diffraction angles and for broadened diffraction lines (FWHM＞1°). Present work deals with detailed analysis of these effects, their corrections and their consequences for the interpretation of diffraction patterns. The proposed methodology and effect of all corrections is shown on the example of montmorillonite intercalated with Al-hydroxy complexes.