Influence of Some Preparation Conditions on Debye′s Relaxation Time and Related Properties of (Pb, La)TiO3 Ceramics

The chemical formula of the samples in this paper is (Pb0.8125 La0.125 0.0625)TiO3 and they are classified into two groups according to the condition of their preparation. The first group of samples was prepared under different sintering times. The other group was prepared under different sintering temperatures. Both groups of ceramics were used to study the influence of the previous conditions on the ferroelectric properties, Debye′s relaxation time and the activation energy. The dielectric measurements have been carried out under electric field of frequencies equal to 1 KHz and 100 KHz. The result of first group showed that the peak value of the dielectric constant εmax increases and shifts slightly to higher temperatures on increasing the value of sintering time ts . The value of εmax tends to saturation at ts ≥ 18 h. The critical relaxation times τc has a similar behavior as the dielectric peak εmax. In the result of second type of sample, the increasing in the value of dielectric peak ε max was faster at low sintering temperatures (1433 ≤ Ts < 1493 K) and tends to saturation at (Ts ≥ 1523 K). The critical relaxation time has a similar behavior as the same as ε max . The interpretation of the dielectric constant behavior is dependent strongly on the grain size and consequently the volume of the domain. Also, the values of Curie Weiss constant (C- ) and the activation energy as a function of ts and Ts have been studied.