Sol-gel prepared copper doped SiO2 glasses

SiO₂ glasses doped with nano-sized copper particles were prepared through sol-gel method. Samples with nominal composition xCu–(1–x)SiO₂ (x=0.02, 0.05, 0.1, 0.2, 0.4) were prepared by hydrolyzing tetraethylorthosilicate with various amounts of Cu(NO₃)₂. The dried gels were heat treated at 400, 500, 600, 700°C for 10 hrs under flowing 5% H₂-95% N₂ mixture gas to reduce Cu⁺² ions to metallic copper. The amorphous nature of the SiO₂ matrix was confirmed by powder X-ray diffraction. The size of particulate copper metal, which was determined by transmission electron microscopy, increases with the temperature of heat treatment and the copper content. The local structure of SiO₂ matrix was probed by FTIR. The silica matrix has no major structural change for gels heat treated at different temperatures and with different copper contents.