Control of selective silicate glass coloration by gold metallic nanoparticles: structural investigation, growth mechanisms, and plasmon resonance modelization

Soda lime silicate oxide glasses are studied to perform coloration thanks to gold nanoparticles' crystallization. This precipitation is conducted by chemical reduction of gold ions with stannous or antimony oxides as reducing agents. A control of the rendered coloration between blank to red shades has been obtained using Sb2O3 agent and appropriate thermal treatments. The glasses remain colorless while heating up to 450 degrees C. Structural glasses evolution is studied by MAS NMR spectroscopy of Si-29 and Na-23 nuclei to investigate the silicate network polymerization change and the modification of sodium/oxygen bond length versus nucleation state and growth of Au nanoparticles. A clear decrease of the Q(2) species part is observed with nanoparticles growth confirmed by the evolution of chemical shift for Na-23 resonance. A slight network polymerization is then showed independently of the only thermal treatment. This structural change could be induced by the antimony oxidation and change towards higher coordinations. Finally, the glasses chemical durability has been studied by leaching tests and shows lower alteration for colored glass. The optical spectroscopy applied to colored glasses has given rise to plasmon resonance phenomena at around 600 nm which is the typical surface plasmon resonance of gold for a refractivemediumindex of 1.5, with a shift of the resonance towards the higher wavelengths with increasing thermal treatment temperature. This shift is modelized by Drude and MIE approaches and confirms the trend observed by UV-visible measurement with an increasing absorption at the SPR correlated to a typical Ostwald growth mechanism according to the increase of the annealing temperature.