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 PbZr1-xTixO3 (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 PbZr1-xTixO3. Our calculated values for the damping constant are in agreement with the observed data for the ferroelectric phase of PbZr1-xTixO3 single crystals. The activation energies calculated from both models are much higher in the ferroelectric phase than the value of k(B)T(C)=0.056 eV at the transition temperature for PbZr1-xTixO3 (x=0.45).