Formation of silver colloids on ion exchanged soda lime silicate glasses by irradiation

The effect of ionizing radiation (gamma rays, X-rays and electrons) on soda lime silicate glasses, in which part of the Na+ was substituted by Ag+ by means of an ionic exchange process, was studied. The techniques of thermally stimulated depolarization current (TSDC) and transmission electron microscopy (TEM) were employed to follow the formation of silver colloids by irradiation. Also the thermoluminescence (TL) of the samples was measured and three peaks between room temperature and 450 C were observed. The TEM and TSDC results agree that, as expected, ionizing radiation promotes the formation of silver colloids on the ion exchanged surface of soda lime glasses. Soft X-rays are much more efficient in the process than gamma rays and electrons. The correlation with thermoluminescence glow curves indicates that the intensity of a TL peak at 230 C can provide a rapid means of evaluating the presence of silver colloids. TL sensitivities, measured as area under the glow curve per unit mass and unit dose, are very similar for ion exchanged and not exchanged samples submitted to X-ray irradiation, although the peak temperatures differ in about 40 C in the two cases. For both electron and gamma irradiated samples, the TL sensitivity drops about an order of magnitude when compared to the X-ray irradiated ones. (orig.)