  Perovskite structure materials based on the Ba1-xGdxTiO3 system, where x =
0.001, 0.002, 0.003, 0.004 and 0.005, were prepared via the Pechini chemical
synthesis route. The dielectric properties have been analyzed over a wide
temperature and frequency range, revealing a significant contribution of the
conduction mechanisms in the dielectric response of the studied ceramics. In
fact, by using the Davidson-Cole formalism, the observed electrical behavior
was found to be associated with relaxation processes related to intrinsic
defects mobility promoted by a thermally-activated polaronic mechanism. The
obtained values of the activation energy for the relaxation processes,
estimated from the Arrhenius law for the mean relaxation time, revealed a
decrease from 0.29 up to 0.21 eV as the Gd-doping concentration increases,
which suggests the conduction process to be associated with the polaronic
effects due to the coexistence of Ti4+ and Ti3+ ions in the structure. Analysis
from the conductivity formalism, by using the Jonscher universal power-law,
confirmed the polaron-type conduction mechanism for the dielectric dispersion,
as suggested by the dielectric analysis, being the nature of the hopping
mechanism governed by small polaron hopping (SPH) charge transport in the
studied Ba1-xGdxTiO3 ceramics.
