Rietveld Refinement
Definition
A full-pattern fitting method for XRD quantification that models the entire diffractogram using crystal structure data for each phase, adjusting phase abundances by least-squares until the calculated and measured patterns agree. Produces weight percentages with uncertainty estimates.
- Input data
- X-ray diffraction (XRD) patterns (full diffractogram)
- Output
- Weight percentages of each phase with uncertainty estimates
- Core technique
- Least-squares fitting of the full diffraction profile
Common questions
What does Rietveld refinement tell you that a regular XRD pattern can't?+
A standard XRD pattern shows peaks, but Rietveld refinement models the entire diffraction profile to extract quantitative phase fractions. It tells you how much of each crystalline phase is present by weight, not just which phases exist. You get actual percentages with uncertainty estimates.
How does Rietveld refinement work?+
It uses least-squares fitting to compare calculated patterns (based on known crystal structure data for each phase) against your measured diffractogram. The software adjusts phase abundances iteratively until the calculated and measured patterns match. This produces precise weight percentages for each phase.
When would a forensic analyst use this instead of just identifying minerals?+
In cases where composition matters to the investigation. For cement, building materials, or clay mixtures, knowing that a sample contains 60% quartz and 40% feldspar is more forensically useful than knowing it contains quartz and feldspar. The quantitative breakdown can link samples or rule out sources.
Related terms
- ASTM C150
- US standard specifying Portland-cement composition limits and performance requirements by type (I through V); referenced in forensic mineral-phase characterisation.
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Explained in these topics
- Cement, Plaster and Building-Material EvidenceA least-squares fitting procedure that extracts quantitative phase fractions from an XRD pattern by modelling the full diffraction profile.
- X-ray Diffraction and Clay MineralogyA full-pattern fitting method for XRD quantification that models the entire diffractogram using crystal structure data for each phase, adjusting phase abundanc...