Formation of quantum-size PbTe microcrystals in sol-gel derived silica and borosilicate glasses

PbTe-doped silica and borosilicate glasses with the particle size ranging from 2 to 15 nm were prepared by the sol-gel method. Under a reducing H₂ gas atmosphere, PbTe microcrystalline phase was produced at a temperature of about 400°C via the initial Te crystalline phase formed at a low temperature, around 300°C. In borosilicate glasses, PbTe microcrystals were found to have a higher growth rate than in silica glasses. The absorption edge was shifted from the infrared to near visible range with a decrease in particle size due to the quantum-size confinement effect.