Electromigrational Depletion (ED) Chronopotentiometry Temperature Dependence of Diffusion in Molten BeF2‐LiF

Abstract

New chronopotentiometric measurements with a Be anode in highly viscous molten 95 mole per cent mole per cent mixture are described in the range of temperature 564°–704°C. The transition is a result of electromigrational depletion (ED) of mobile nonelectroactive lithium ions. The equation of the chronopotentiogram is derived with the linear phenomenological equations of the thermodynamics of irreversible processes. Interdiffusion coefficients are derived from analysis of emf‐time data along the chronopotentiograms rather than from a transition time alone. The low values, 3 × 10−9–3 × 10−7 cm2/sec and high Arrhenius energy, 50.5 kcal/mol, are compared with the results of molecular dynamics computer experiments and the values of other transport coefficients in this and related systems.