Heavy ion Rutherford backscattering spectrometry (HIRBS) study of barium diffusion in borosilicate glass

Diffusion of barium in borosilicate glasses containing sodium and calcium has been studied using heavy ion Rutherford backscattering spectrometry (HIRBS) using 30 MeV F-19 beam. A thin layer (25 mu g/cm(2)) of BaCl2 was vacuum evaporated on the polished surface of the glass samples which were then annealed at different temperatures (573-723 K) and subsequently subjected to HIRBS measurements. It was observed that introduction of 10 mole% of calcium in place of sodium results in increase in the activation energy of diffusion of barium by about 30%. This indicates that alkaline earth ions retard the diffusion process in borosilicate glass. The results corroborate the data obtained on diffusion of sodium by radiotracer method. The results have been explained in terms of the increasing rigidity of the glass network with introduction of alkaline earth ions. (C) 2007 Elsevier B.V. All rights reserved.