PulverRietveldVerfeinerung

PulverRietveldVerfeinerung, commonly known as Rietveld refinement for powder diffraction data, is a computational method used to analyze the structure of crystalline materials. Developed by Hugo Rietveld in 1966, it allows for the determination of crystal structures directly from powder diffraction patterns, rather than single-crystal diffraction. This technique is particularly valuable because powder diffraction is often easier and cheaper to perform than single-crystal X-ray diffraction.

The core principle of Rietveld refinement involves fitting a calculated diffraction pattern to an observed one. The calculation is based on a proposed crystal structure, including lattice parameters, atomic positions, and thermal parameters. By adjusting these structural parameters and other profile parameters that describe the shape and intensity of the diffraction peaks, the method minimizes the difference between the calculated and observed patterns. This iterative process leads to a refined structural model that best represents the experimental data.

Key advantages of Rietveld refinement include its ability to handle complex structures, its suitability for quantitative phase analysis (determining the relative amounts of different crystalline phases in a mixture), and its applicability to a wide range of materials, including those that are difficult to grow as single crystals. It is a cornerstone technique in materials science, solid-state chemistry, mineralogy, and many other fields that rely on understanding crystalline matter.