Control of the valence state of copper ions through the addition of P2O5 in sol-gel silicate glass

The copper containing glass, particularly with rich Cu+ ions, is a promising material for antibacterial and luminescent. The valence control of Cu+/Cu2+ in melt-quenching glass has been widely investigated, but sol-gel method was rarely extended. Herein, the Cu+ rich silicate glass was successfully prepared by introducing the P2O5 as modifying agent in the sol-gel method fabricated phosphosilicate glasses, briefed as 10CaO-(90-x)SiO2-xP2O5 (x = 0, 2.5, 5, 7.5, 10 mol%)- 5CuO. It is found that the high content of P2O5 will generates more Cu+ in the gel forming stage and result in a Cu+ rich glass. While, the content of Cu+ drops with excessive P2O5 additives in the prepared glass. The highest Cu+ content was obtained in glass with 7.5 mol% P2O5. Because phosphate glass network is looser than silica-oxygen glass network, which lead to copper ion in the phosphate cluster as a charge compensator is easier to be oxidized compared with in the Si–O network. Therefore, our study paved a new way for designing Cu+ rich glass by sol-gel method.