Birefringence measurements of creep near an electrode tip in transparent PLZT

Birefringence measurements of time-dependent, creep polarization and strain were made in bulk ceramic samples of PLZT 8/65/35. Two specimen configurations were used: a fixed uniform electric field to measure the creep response and correlate birefringence with strain and polarization, and specimens with a partial surface electrode, to study the local behaviour near the tip of a surface electrode. At low values of electric displacement, the electric displacement depended upon the principal strain difference in a quadratic fashion whereas the birefringence varied linearly with the principal strain difference. Three distinct regimes of switching were identified, corresponding to the nucleation of ferroelectric domains, rapid switching and saturation in the process of domain growth. Finally it is shown that the birefringence measurements near an electrode tip give the spatial evolution of principal strain difference.