X-Ray Powder Diffraction as a Tool to Investigate the Ultrastructure of Nanoparticles

The potential of x-ray powder diffraction to analyze the size and ultrastructure of metallic nanoparticles (silver, gold, silver-gold alloy, and calcium phosphate) is demonstrated. By the Rietveld analysis, it is possible to estimate the crystallite size for such nanoparticles, even if they are very small (4 nm), using the effect of peak broadening in small crystallites. The results correspond well to crystallite size as determined by transmission electron microscopy (TEM), also confirming the twinned nature of the metallic nanoparticles. For calcium phosphate nanorods which are not twinned, the results by x-ray powder diffraction and TEM are in good agreement.