Raman study of an electric-field-induced phase transition in Pb(Zn_1/3Nb_2/3)O₃-8%PbTiO₃

Electric-field-induced structural transition of a single crystal Pb(Zn_1/3Nb_2/3)O₃-8%PbTiO₃ grown in the (001) direction was studied by use of Raman scattering spectroscopy. By comparing the changes in Raman spectra induced by the electric field with the temperature-dependent changes, we could confirm that the structural transition to tetragonal phase is initiated at a threshold electric field E_c1 and completed at higher transition field E_c2. In the electric-field range from E_c1 to E_c2, it is found that rhombohedral and tetragonal phases coexist. The lower threshold field E_c1 is found to coincide with the field at which the strain rises abruptly in the strain electric-field hysteresis loop while the upper threshold field E_c2 corresponds to the electric field where a slope change is observed in the high-field saturation region beyond the hysteresis loop.