Rietveld Analysis & XRPD Phase Analysis
Full-pattern fitting for atomic structure refinement and quantitative composition analysis
Rietveld Analysis
The Rietveld method is a full-pattern fitting method in which a calculated profile is fitted to a measured pattern by varying a range of crystallographic parameters. It is used for atomic structure refinement and for precise determination of the characteristics of a unit cell.
The method derives crystallographic parameters such as lattice constants, atom coordinates within the unit cell, site occupancy and preferred orientation. In addition, Rietveld refinement can be used to reveal the quantitative composition of multiphase mixtures.
XRPD Phase Analysis
The XRPD pattern of a crystalline phase is directly related to its crystalline structure, and an XRPD pattern of a compound mixture is generally the sum of the XRPD patterns of the separate single compounds.
XRPD pattern decomposition often serves as the preliminary step before the subsequent identification of unknown compounds in a mixture by comparison with the available databases. Phase analysis using XRPD is ideal for the analysis of polymorphic mixtures, investigations of phase transformations in compatibility studies, and optimization and quality control of the final formulation. In addition, XRPD full-pattern analysis allows for the (semi-)quantitative analysis of amorphous compounds in the formulation.