Modifications in silver-doped silicate glasses induced by ns laser beams

Glass layers for planar light waveguides prepared by Ag-Na ion exchange of different silicate glasses in molten salt baths are annealed and/or irradiated with a laser beam in the UV region, with different energy density values and total pulse numbers. The samples are mainly characterized by optical absorption spectroscopy, luminescence spectroscopy, and Rutherford backscattering spectrometry, in order to determine the role of irradiation parameters and of the host matrix structure in the aggregation phenomena. Photoluminescence spectroscopy gave information regarding the presence of Ag multimeric aggregates, the primal seeds for the growing (nano)crystals. The appearance of the plasmon resonance band in the optical absorption spectra proved the formation of Ag clusters and allowed the evolution steps of the clusterization process to be followed as a function of the energy deposited during the laser irradiation.

Research highlights▶ Ion exchange from molten salt bath can be used to dope silicate glasses (soda-lime and borosilicate) with Ag. ▶ With a suitable choice of the post-exchange treatments (thermal annealing and/or UV laser irradiation) it is possible to induce the silver aggregation, namely to obtain metal nanocluster composite glasses. ▶ The role of irradiation parameters and of the host matrix structure in the aggregation phenomena are investigated to better understand the formation and the dissolution of the nanoparticles. ▶ Thermal treatments are able to induce formation of aggregates of few silver ions (for low T annealing) and silver metal particles 2-3 nm in size (for high T annealing). Laser irradiation was able to induce Ag nanoparticles formation in the as-exchanged soda-lime samples. ▶ In the previously annealed Ag-doped soda-lime samples, the laser irradiation with a very large number of consecutive pulses induces a fragmentation of the silver nanoparticles. ▶ No effects were observed by laser irradiation of the Ag-doped BK7 glass samples.