Mutual diffusion coefficients of the systems (Rb,Ag)Cl and (Alk,Ag)NO3 with Aik = Li, Na, K,
Rb, and Cs are reported. Experiments in the nitrate systems were performed with either holographic
real-time interferometry or Savart interferometry under free-diffusion boundary conditions. Initial
diffusion boundaries were created using a flowing junction cell or bottom layer cells. Mutual
diffusion coefficients in the system (Rb,Ag)Cl were measured with digital image holography, a
newly developed interferometric technique. Some experiments were performed with Savart
interferometry as an internal consistency check.
In the nitrate systems diffusion data were collected in a temperature range from the melting
points of the mixtures up to 603 K over the whole accessible concentration range. The D values are
considered to be accurate to ±1-3 %. The results have been correlated using Arrhenius-type
equations. Furthermore the concentration dependence of the mutual diffusion coefficient at 573 K is
discussed. The data are fitted to parabolas of the form D = a2x22 + a1x2 + a0, where x2 denotes the
mole fraction of the silver nitrate. For all systems, except (Li,Ag)NO3, parameters a2, a1 and a0
show a clear linear proportionality to the radii of the alkali ions. Trace diffusion coefficients are
extrapolated and discussed.
Mutual diffusion coefficients in the system (Rb,Ag)Cl with xAgCl = 0.61 were measured in a
temperature range between 573 K and 748 K. The results show an Arrhenius behaviour with
D = (1.37 ± 0.10) m2s-1 exp(-(20.7 ± 0.4) kJ mol-1(RT)).