Quantitative Phase Analysis (sometimes called also Standardless Phase Analysis, Multiphase Rietveld Phase Quantification, Rietveld Quantitative Analysis or Rietveld XRD Quantification) is a powerful method for determining the quantities of crystalline and amorphous components in multiphase mixtures. The method relies on the simple relationship

where W is the relative weight fraction of phase p in a mixture of n phases, and S, Z, M, and V are, respectively, the Rietveld scale factor, the number of formula units per cell, the mass of the formula unit (in atomic mass units) and the unit cell volume (in Å3). It is very important to know that commonly used Relative Intensity Ratio (RIR) method is simply not correct and should not be used. Please read our corresponding Technote, where we give proof of inadequacy of RIR method. It should be realized that Rietveld Phase Quantification method for quantification of mixture of 20 phases (with total 6000 reflection) is 30,000 times more powerful than RIR method for quantification of just two phase mixture.

Advantages of Rietveld Quantitative Analysis

• The calibration constants are computed from reliable structural data, rather than by laborious experiments

• All reflections in the pattern are explicitly included for calculation

• The effects of preferred orientation and extinction are reduced, since all reflection types are considered

• Crystal structural and peak profile parameters, particle statistics, microabsorption etc are refined as part of the same analysis.