Formation of silver nanoparticles in Li 2 B 4 O 7 -Ag 2 O and Li 2 B 4 O 7 -Gd 2 O 3 -Ag 2 O borate glasses.

Results of investigations of 98.0Li2 B4 O7 -2.0Ag2 O and 97.0Li2 B4 O7 -2.0Ag2 O-1.0Gd2 O3 glasses with Ag nanoparticles (Ag NPs), formed by thermal treatment in vacuum and in air, are presented. Intensive plasmon absorption bands, connected with Ag NPs, were observed in their optical transmission spectra. It is ascertained that in volumes of both glasses there is formed a small number of Ag NPs, whereas their main mass is concentrated near the surface of samples. The mechanism of Ag NPs formation is proposed. A conclusion is drawn that annealing in vacuum does not necessarily require the presence of reducing ions, whereas formation of nanoparticles at annealing in air is impossible without reducing agents. Structural defects play a decisive role in the Ag NPs nucleation process. Radii of formed Ag NPs are estimated by the half-width of plasmon bands, and by means of small-angle x-ray scattering.