Ion conducting rotor phases are high-temperature modifications of simple in
organic salts with typically cubic structure. Here the polyatomic tetrahedr
al anions like SO42- or PO43- show considerable rotational disorder, while
the cations exhibit fast ion conductivity. A long lasting dispute concentra
tes on the question if and how the anion reorientational motion influences
or enhances the cation transport in these materials. We report new results
from quasielastic neutron scattering experiments on several ion conducting
rotor phases, viz., Na3PO4, Li2SO3, and LiNaSO4. Sodium ion diffusion in Na
3PO4 has been examined on the backscattering spectrometer IN16. Here the da
ta can easily be interpreted on the basis of the Chudley-Elliott model, yie
lding reasonable values for jump distance, mean residence times, and diffus
ion coefficients. While in Na3PO4 the linewidths due to anion reorientation
(studied in an earlier time-of-flight measurement) and cation hopping diff
er by roughly three orders of magnitude, the situation in Li2SO4 and LiNaSO
4 is completely different: here both types of motion have a similar time sc
ale, and the time-of-flight experiment reveals both diffusional and reorien
tational contributions to the quasielastic scattering. (C) 2001 Elsevier Sc
ience B.V. All rights reserved.