Rietveld refinement

The Rietveld method is a Dutch physicist by Hugo Rietveld (* 1932) in 1966 originally for the crystal structure analysis of polycrystalline samples developed by neutron radiation calculation method. It is used since 1977 for examinations with X-rays. The Rietveld method for quantitative phase analysis, that is for the quantitative determination of the crystalline components of a powder sample, used since the mid- 1970s.

Principle

The X-ray diffraction pattern (also XRD diffractogram or ) a polycrystalline substance is regarded as a mathematical function of the diffraction angle, which is also dependent on the structural parameters. These are given by the spatial arrangement of atoms, that is the crystal structure. Starting from an initial model of the atomic arrangement of these structural and additionally instrumental parameters are further refined. As a method in this case usually is the mathematical method of least squares applied. This refinement steps are repeated until such time as, ideally, between the calculated and found XRD pattern, there are no more differences. In practice, this case can hardly be achieved, however.