X-ray irradiation induced reduction and nanoclustering of lead in borosilicate glass†
We have studied the formation of nanoparticles in lead sulfide (PbS)-doped borosilicate glass subjected to a two-step nucleation and growth heat treatment using in situ small-angle X-ray scattering (SAXS). The microstructure produced was subsequently characterized using X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). While PbS nanocrystals of ca. 2 nm diameter are formed throughout the sample during the heat treatment, larger monodisperse Pb nanocrystals (diameter ca. 50 nm) are formed due to exposure to the X-ray beam, yielding space-selective nanoparticle growth. Time-resolved SAXS spectra are in the early stages consistent with diffusion-limited growth of the Pb particles. We attribute the X-ray-induced formation of nanocrystalline Pb to X-ray photoreduction of the Pb2+ atoms.