Polarized Micro-Raman Study of the Temperature-Induced Phase Transition In 0.67 Pb(Mg1/3Nb2/3)O3-0.33PbTiO3

Polarized Raman spectra of ferroelectric relaxor 0.67Pb(Mg1/3Nb2/3)O3-0.33PbTiO3 (0.67PMN-0.33PT) single crystal are systematically investigated in a wide temperature range from -196 to 600°C by micro-Raman scattering technique. The results clearly reveal that there are two structural phase transitions in such composite ferroelectric relaxor: the rhombohedral-tetragonal (R - T) phase transition and the tetragonal-cubic (T - C) phase transition. The former occurs at about TR-T = 34°C, corresponding to the vanishing of the soft A1 mode at 106 cm−1 recorded in the parallel polarization. The latter appears at about TT-C = 144°C, which can be verified with the vanishing of mode at 780 cm−1 measured in the crossed polarization.