Diffusion coefficients of sodium in barium borosilicate glasses having varying

concentration of barium were determined by heterogeneous isotopic exchange

method using 24Na as the radiotracer for sodium. The measurements were carried

out at 748 to 798K to obtain the activation energy (Ea) of diffusion. The Ea values

were found to increase with increasing barium content of the glass, indicating that

introduction of barium in the borosilicate glass hinders the diffusion of alkali metal

ions from the glass matrix. The results were explained in terms of the electrostatic

and structural factors, with the increasing barium concentration resulting in

population of low energy sites by Na+ ions and, plausibly, formation of more tight

glass network. The leach rate measurements on the glass samples showed similar

trend.

Effect of Barium on Diffusion of Sodium in Borosilicate Glass. R.K.Mishra,

S.Kumar, B.S.Tomar, A.K.Tyagi, C.P.Kaushik, K.Raj, V.K.Manchanda: Journal of

Hazardous Materials, 2008, 156[1-3], 129-34