Preparation of gold ruby glasses by the sol-gel method

Abstract

The preparation of ruby glasses in pure silica matrices, as well as the study of the colouration mechanisms have been carried out. For this purpose, TEOS solutions were prepared with gold concentrations between 0.0005 and 0.5 wt%. Subsequent to a gelling process at 30 and 60 °C, colour variation was studied as a function of the treatment temperature by means of UV-VIS spectroscopy. The X-ray diffraction spectra confirmed the presence of elemental gold in the samples with a relatively high gold content. Transmission electron microscopy provided evidence of the formation of colloidal gold aggregates responsible for the colouration phenomenon. The photoluminescence spectra allowed to follow the changes of the redox state of the gold in the gels confirming the elemental nature of the colloidal colourant particles.