What Is Crystallite Size and Strain Analysis?

XRD and SAXS to determine particle and pore sizes and strain

Physical and chemical properties of nanoparticles and nanocrystalline materials are strongly influenced by their particle size, shape and structural strain, including rheology, surface area, cation exchange capacity, solubility, reflectivity, etc. 

Crystallite size is performed by measuring the broadening of a particular X-ray diffraction (XRD) peak in a diffraction pattern associated with a particular planar reflection from within the crystal unit cell. It is inversely related to the FWHM (full width at half maximum) of an individual peak: the more narrow the peak, the larger the crystallite size. This is due to the periodicity of the individual crystallite domains, in phase, reinforcing the diffraction of the X-ray beam, resulting in a tall narrow peak. If the crystals are defect free and periodically arranged, the X-ray beam is diffracted to the same angle even through multiple layers of the specimen. If the crystals are randomly arranged, or have low degrees of periodicity, the result is a broader peak.