On the stress state of silver nanoparticles in ion-implanted silicate glasses

Soda-lime glasses were implanted with 1x1016 and 2x1016 Ag+ ions/cm2 using an acceleration voltage of 200 kV. Size of silver particles formed as well as their distribution within the implanted region and the structure of these particles were analysed by transmission electron microscopy to describe interactions between the glass network and silver species. In agreement with electron microscopy observation, RBS measurements reveal a bimodal spatial distribution of Ag. This distribution, however, does not correspond to simple theoretical predictions. The lattice parameter changes of individual Ag nanoparticles as determined from high-resolution electron microscopy images indicate the presence of strong compressive stresses acting on the particles which are caused by the surrounding glass matrix. The compressive stress was approximated to 29 GPa, exceeding by far the elastic limit of the glass matrix. Therefore, a severe compression of the surrounding glass matrix is expected too, strongly affecting the migration and aggregation of silver, which results in an unusual distribution of silver species. The observed difference between experimental and theoretical distribution of the implanted species can be explained in terms of these processes