Lithium diffusion in vitreous jadeite (NaAlSi206): An ion microprobe investigation
Roselieb, Knut; Chaussidon, Marc; Mangin, Denis; Jambon, Albert
published: May 1, 1998
ArtNo. ESP154017202001, Price: 29.00 €
We investigated Li tracer diffusion in glass and supercooled melt of jadeite composition at temperatures between 485 and 900 °C, 1 bar pressure, and run times from 5 to 30 min. The experiments were performed using the thin source technique, Li concentration profiles being measured using an ion microprobe. Diffusivities are independent of the duration of the experiment and the amount of Li initially introduced into the jadeite glass. The temperature dependence of Li diffusivity is appropriately described by an Arrhenius equation D = Doexp (-E/RT) over the investigated temperature range and a linear least squares regression yields Do = 1.44 ( + 0.33/ -0.27) · 1O-6 m2/s and E = 79 ± 2 kl/mol. The relationship between activation energy and radius of the diffusing alkalies Li, Na, K, Rb and Cs exhibits a clear minimum for the activation energy of Na in vitreous jadeite. Diffusivities decrease with increasing size of the alkali from Na towards Cs, whereas Li and Na diffusivities are similar, with slightly lower diffusivities for Li.