Measurement of crystallite size distribution in polycrystalline materials using two-dimensional X-ray diffraction

A method of determining crystallite size distribution in a sample of a polycrystalline material, the method comprising:

• providing an X-ray diffractometer with an X-ray beam source and a two-dimensional X-ray detector;
• positioning the sample at a first predetermined orientation relative to the X-ray beam source and detector such that crystallites in the sample produce diffraction spots on a detection surface of the detector, each diffraction spot corresponding to a different crystallite in the polycrystalline material;
• measuring the intensities of the diffraction spots within a defined detection window of the detector that includes a finite range of diffraction angles;
• rotating the sample in a rocking direction relative to the X-ray beam source and the detector and measuring the intensities of the diffraction spots at each of a plurality of different rocking angles along the rocking direction, an angular separation between adjacent rocking angles being such that each diffraction spot is measurable in the detection window at a plurality of said angles;
• recording a peak intensity value for each detected diffraction spot for which the detected intensities both increase and decrease across a continuous range of rocking angles;
• calculating a corresponding crystallite volume from each recorded peak diffraction intensity value;
• and
• determining the crystallite size distribution using said calculated crystallite volumes.