Effective chemical diffusivities in the proton conductors, SrCe0.95Yb0.05O3 and SrZr0.95Yb0.05O3, were determined electrochemically. A proton concentration gradient was first set up by using the Hebb-Wagner technique, and the temporal evolution of the voltage across the electrolyte was then measured. This permitted the estimation of proton diffusivities. The results for SrCe0.95Yb0.05O3 could be described by:

D(cm2/s) = 0.002185 exp[-0.46(eV)/kT]

for temperature ranging from 300 to 600C, while the results for SrZr0.95Yb0.05O3 could be described by:

D(cm2/s) = 0.0137 exp[-0.58(eV)/kT]

over the same temperature range.

T.Schober, J.Friedrich, J.B.Condon: Solid State Ionics, 1995, 77, 175-9