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 ~ 0.5 μm into the glass when the glass was immersed in the AgNO₃ solution at 80 °C. Ag nano-particles (NPs) and PbS QDs were formed after heat-treatment at temperatures of 420–460 °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 °C in Ag⁺-diffused regions and this implies that PbS QDs form preferentially using Ag NPs as nucleating agents.