The present paper is essentially a study of the influence La –ions on
Debye′s relaxation time and consequently the activation energy in
(Pb1-1.5x Lax 􀀀0.5x) TiO3 ceramics. The dielectric measurements have been carried
out under electric field of frequencies equal to 1 and 100 KHz. The results
which were calculated by Debye′s equation for the ferroelectric materials
revealed that the sample with x= 20 mole % La characterizes with highest value
of the critical relaxation time. The interpretation of the anomaly peak of
dielectric constant of the sample with x= 20 mole % La was attributed to the
increasing the volume of the domain. Curie-Weiss constant (C) and activation
energy as a function of La- content have been determined. The calculated
activation energy for the samples was found to be dependent on three
parameters: La–ions, phase transition temperature and quality of ceramics
which, in turn, is a function of Curie-Weiss constants.