Deviations from the Summerfield scaling in the piezoelectric   PbZr0.57Ti0.43O3
  Extending our earlier observations of the deviations from Summerfield scaling in a crystalline ferroelectric system of SBCT, we have studied the scaling of conductivity in another ferro/piezoelectric perovskite crystalline oxide, PZT. The deviations from Summerfield scaling are found at T greater than TC. Correction to the Summerfield scaling is achieved by the application of the Random Barrier Model and master cures are constructed with a value of the scaling function alpha 3.2. As in the case of SBCT, deviations still occur at T greater TC. The master curves are constructed from the conductivity data sigma prime fitted to a modified Jonscher law in the frequency range 10 to 1e5 Hz over the temperature region 30 to 480 degrees C. The positive values of alpha indicate coulomb exchange between the interacting particles. This work provides an additional example which allows us to believe that crystalline systems as well may follow the scaling laws, not only amorphous glasses, as was previously believed. 
M. Mahesh Kumar and Z.-G. Ye