Temperature dependence of the Brillouin frequency shift and the linewidth of the LA mode in the ferroelectric phase of PZT-x (PbZr1−xTixO3)

The temperature dependence of the Brillouin frequency and the linewidth of the LA mode is studied for the concentration of x=0.45 in the ferroelectric phase of PbZr_1-xTi_xO₃ (PZT-x) within the temperature range of 443 to 656 K (T_C=657 K). Using the experimental data for the Brillouin frequency of the LA mode as an order parameter below T_C the temperature dependence of the linewidth (FWHM) is calculated by the pseudospin-phonon coupled model and the energy fluctuation model for the lead titanate zirconate (x=0.45). Additionally, the activation energies are compared from the damping constant (linewidth) using both models for the temperature range of 443 to 656 K in the ferroelectric phase of PbZr_1-xTi_xO₃. Our calculated values for the damping constant are in agreement with the observed data for the ferroelectric phase of PbZr_1-xTi_xO₃ single crystals. The activation energies calculated from both models are much higher in the ferroelectric phase than the value of k_BT_C=0.056 eV at the transition temperature for PbZr_1-xTi_xO₃ (x=0.45).