ANALYSIS OF BIREFRINGENCE BEHAVIOR IN THE DETERMINATION OF THE CHARACTERISTICS TEMPERATURES OF TRANSPARENT FERROELECTRIC RELAXOR CERAMIC SYSTEMS

摘要

The thermal evolution of the electric field-induced birefringence, δ(△n(E)) vs T, resulted from the Kerr and Pockels electro-optical effects, was considered in the verification of critical temperatures of transparent relaxor ferroelectric ceramics. (Pb,La)(Zr,Ti)O3 ceramics, for La/Zr/Ti=9/65/35 were used as a representative relaxor ferroelectric system. The temperature of transition between the normal ferroelectric (FE)/ergodic ferroelectric relaxor (EFR) or EFR /non-ergodic ferroelectric relaxor (NEFR) and NEFR/paraelectric (PE) states, identified as T_f (freezing temperature) and T_b (Burns temperature) respectively, as well as temperatures associated to anomalous behaviors identified as T_ε'm (maximum electrical permittivity) and T*, could be determined. These results were associated with polarization behavior observed through the pyroelectric current and real part of the dielectric permittivity characterization, being used to confirm me values of the critical temperatures evaluated by the birefringence measurements.