title: Effect of barium on diffusion of sodium in borosilicate glass.
abstract: Diffusion coefficients of sodium in barium borosilicate glasses having varying concentration of barium were determined by heterogeneous isotopic exchange method using (24)Na as the radiotracer for sodium. The measurements were carried out at various temperatures (748-798 K) to obtain the activation energy (E(a)) of diffusion. The E(a) 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 have been 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 show similar trend.
authors.affiliation: Waste Management Division, Bhabha Atomic Research Centre, Mumbai, India.
authors.forename: R K
authors.initials: RK
authors.lastname: Mishra
authors.forename: Sumit
authors.initials: S
authors.lastname: Kumar
authors.forename: B S
authors.initials: BS
authors.lastname: Tomar
authors.forename: A K
authors.initials: AK
authors.lastname: Tyagi
authors.forename: C P
authors.initials: CP
authors.lastname: Kaushik
authors.forename: Kanwar
authors.initials: K
authors.lastname: Raj
authors.forename: V K
authors.initials: VK
authors.lastname: Manchanda
mesh_terms: D001464:Barium / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D004058:Diffusion; D005898:Glass; D012964:Sodium / Q000737:chemistry*; D055672:Static Electricity; D013696:Temperature
chemical_list: D001464:Barium; D012964:Sodium