Self diffusion and ion exchange in the glass system Li2O-Na2O-Al2O3-SiO2

Abstract

Lithium and sodium self diffusion, the Li+ - Na+ interdiffusion and the equilibrium of the Li+ - Na+ ion exchange were investigated at 450 °C on glasses of the composition x Li2O, (31.8 - x) NA2O, 5.8 AI2O3, 62.4 SiO2. Both self diffusion and interdiffusion coefficients, which were between about 5 · 10^-9 and 10^-7 cm^2 s^-1 showed a pronounced mixed alkali effect. Experimentally determined and from the Nernst-Planck model calculated interdiffusion coefficients match reasonably, occurring differences are discussed structurally. The Li+ - Na+ equilibrium data demonstrate a preferred selectivity for Li+ ions.