Slow dynamics in ion-conducting sodium silicate melts: Simulation and mode-coupling theory

Calculations within the mode-coupling theory of the glass transition (MCT) are used to elucidate the structure-dynamics relation in sodium-silicate melts (NS x ) of varying sodium concentration. Using only the partial static structure factors from molecular-dynamics (MD) computer simulation as input, MCT qualitatively reproduces the large separation in relaxation time scales between the sodium and the silicon/oxygen components peculiar to such mixtures. This shows that it is possible to explain the fast sodium-ion dynamics observed in sodium-silicate melts using MCT as a microscopic theory, and from the averaged equilibrium structure alone.