Relationship between structure, entropy, and mobility in network-forming ionic melts

Abstract

Diffusivity, ionic conductivity, and viscosity of network-forming ionic melts are examined using molecular dynamics simulations of BeF₂ and SiO₂ melts. These tetrahedral, network-forming ionic melts are shown to possess a conductivity anomaly, in addition to waterlike viscosity and diffusivity anomalies, corresponding to a striking breakdown of the Nernst-Einstein relation. The contrasting scaling behavior of the different mobility measures with different structural contributions to the excess entropy is demonstrated.