Lead sulfide quantum dots in glasses controlled by silver diffusion

Precipitation of PbS quantum dots (QDs) in silicate glasses controlled by Ag+ ion diffusion was investigated. Ag+ ions penetrated similar to 0.5 mu m into the glass when the glass was immersed in the AgNO3 solution at 80 degrees C. Ag nano-particles (NPs) and PbS QDs were formed after heat-treatment at temperatures of 420-460 degrees C for 10 h. PbS QDs in Ag+-diffused regions photoluminesced at longer wavelengths than did those in Ag+-free regions. This indicates that PbS QDs thus formed in regions containing Ag NPs were larger than those in Ag+-free regions and this size difference was confirmed from the transmission electron microscope images. PbS QDs can grow at temperature as low as 420 degrees C in Ag+-diffused regions and this implies that PbS QDs form preferentially using Ag NPs as nucleating agents. (C) 2012 Elsevier B.V. All rights reserved.