On the correlation between the thermal and electrical transport in ionic conductors

Simultaneous measurements of the thermal diffusivity and electrical conductivity of some 'ion conducting' polymer-solid and solid-solid composites have led us to establish, for the first time, a correlation between these quantities in ionic conductors similar to the Wiedmann-Franz law applicable to 'electron conducting' metals according to which the ratio of thermal to electrical conductivity is almost constant. However, the proportionality constants for the 'ionic conductors' are found to be different for systems with (a) different mobile species, namely H+, Li+ or Ag+ and/or (b) different morphology, i.e. polymeric or polycrystalline.