Conductivity-Viscosity-Structure: Unpicking the Relationship in an Ionic Liquid

Mathieu Salanne (1) , Christian Simon , Pierre Turq (1) , Paul A. Madden (2)

1 LI2C - Liquides Ioniques et Interfaces Chargées
2 Department of Chemistry

The relationships between the ionic mobility, the viscosity, and the atomic-scale structure are investigated in computer simulations of mixtures of LiF and the network glass-forming material BeF2. The simulations span a wide range of compositions, across which the fluidity of the system changes greatly due to the break-up of the Be-F network by the addition of the LiF. The relationship between the conductivity and viscosity passes from that expected for independently diffusing ions in the dilute mixtures to strongly decoupled Li+ migration through a viscous network at higher concentrations. The transition between these régimes is linked to the changing local and intermediate-scale structure in the melts. The decoupling phenomenon is associated with the appearance of migration channels in the network which leads to cooperative effects in the Li+ migration.

Domaines: Chimie-Physique [physics.chem-ph]

Mathieu Salanne, Christian Simon, Pierre Turq, Paul A. Madden. Conductivity-Viscosity-Structure: Unpicking the Relationship in an Ionic Liquid. Journal of Physical Chemistry B, 2007, 111 (18), pp.4678-4684. ⟨10.1021/jp067073a⟩. ⟨hal-00169168⟩