The kinetics of the formation of CdSe nanocrystals in sodium-zinc-silica glass

The kinetics of precipitation of CdSe nanocrystals in sodium-zinc-silica glass subjected to a two-stage heat treatment at different temperatures of the primary and secondary heat treatments has been studied by small-angle X-ray scattering (SAXS). The primary low-temperature heat treatment is accompanied by the nucleation of crystallization centers, i.e., supercritical nucleation centers. During the secondary heat treatment, crystals largely grow on the formed centers. In this case, the crystals are distributed in the bulk of the glass in a certain order, which apparently results from the regular pattern of distribution of the crystallization centers formed during the primary heat treatment. It has been found that the precipitated nanocrystals have a narrow size distribution at all stages of heat treatment. After the completion of precipitation of the crystalline phase, a stable structure is formed. The crystal sizes and the volume fraction of the phase do not change within the measurement accuracy (±1–2%) for the heating times that are at least an order of magnitude longer than the duration of the precipitation stage.