Mechanisms for Alkali Leaching in Mixed-Na-K Silicate Glasses
The kinetics of alkali removal from (1-X) Na2O·XK2O·3SiO2 glasses were studied using pH stat titration techniques, solution analyses, and elemental depth profiling by Rutherford backscattering spectrometry and elastic recoil detection. In the first stage of leaching (t1/2 kinetics), the interdiffusion coefficients measured for the exchange of alkali cations by H3O+ are orders of magnitude greater than the alkali diffusion coefficients in bulk glass and show no evidence of the mixed-alkali effect. At longer times, the rate of alkali removal becomes constant with time, but selective alkali leaching is still observed rather than uniform dissolution. These results support a model where the rate determining step for alkali leaching is the rate at which molecular water diffuses into the glass.
B. C. Bunker et al., "Mechanisms for Alkali Leaching in Mixed-Na-K Silicate Glasses," Journal of Non-Crystalline Solids, vol. 58, no. 2-3, pp. 295-322, Elsevier, Nov 1983.
The definitive version is available at http://dx.doi.org/10.1016/0022-3093(83)90031-5
Materials Science and Engineering
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