Photoluminescence characteristics of sintered silica glass doped with Cu ions using mesoporous SiO2-PVA nanocomposite

Monolithic silica glasses doped with Cu ions were prepared by immersing a mesoporous SiO2-polyvinyl alcohol (PVA) nanocomposite in a copper nitrate solution followed by sintering at 1100 °C for 12 h in air. The Cu ions were reduced from divalent to monovalent during the sintering process and consequently Cu+ was doped into the silica glass matrix. The sintered glass possessed blue or yellow photoluminescence (PL) under UV irradiation, depending on the total concentration of Cu ions in the sintered silica glass. At a lower concentration below 30 ppm, the isolated Cu+ existed in the glass matrix resulting in the blue PL. However, above 70 ppm, the Cu+-Cu+ pairs were present, exhibiting the yellow PL. It was demonstrated that the PL characteristics of the sintered silica glasses doped with monovalent copper ions were affected by the total concentration of Cu ions in the glass, which can be adjusted as a function of the immersion conditions.