Optical Indices and Polarization Properties of Relaxor Ferroelectric 0.91Pb(Zn_(1/3)Nb_(2/3))O_3-0.09PbTiO_3 Single Crystal

摘要

Optical, pyroelectric, and dielectric properties for poled and annealed crystals of the relaxor ferroelectric Pb(Zn_(1/3)Nb_(2/3))O_3-PbTiO_3 with compositions near the MPB, were measured as function of temperature. The results of refractive index measurements clearly displayed the change of crystal structure symmetry from optically anisotropic to isotropic on macroscopic scale at approx 190 deg C. The local, random, and dynamic polarization characteristic was investigated at temperatures well above 190 deg C. Polarizations derived from the pyroelectric measurements showed dependence on poling conditions and was substantially different from that derived from index measurement. The polarization precursor effects are considered to clarify these observations.