Effect of Silver Ion-Exchange on the Precipitation of Lead Sulfide Quantum Dots in Glasses.

This article reports the effect of Ag+ ion-exchange on the precipitation of PbS quantum dots ( QDs) in silicate glasses. The glasses were subjected to ion-exchange in AgNO3 salt melts at 260°C for 60 s. Ag nanoparticles ( NPs) and PbS QDs precipitated after heat treatment at temperatures of 440°C-460°C for 10 h. Photoluminescence wavelength λPL of PbS QDs was longer (~1525 ≤ λPL ≤ ~1580 nm) in Ag+ ion-exchanged regions than in Ag+-free regions (~1030 ≤ λPL ≤ ~1200 nm). Average diameter D of PbS QDs estimated by calculation and TEM images was larger in Ag+ ion-exchanged regions (~5.2 ≤ D ≤ ~5.5 nm) than in Ag+-free regions (~2.4 ≤ D ≤ ~3.3 nm). Ag NPs that formed during heat treatment provided the sites for heterogeneous nucleation of PbS QDs and promoted the precipitation of PbS QDs in glasses. [ABSTRACT FROM AUTHOR]