Internal bias field relaxation in poled Mn-doped Pb(Mn1/3Sb2/3)O3–Pb(Zr,Ti)O3 ceramics

The frequency, electric field cycling and temperature dependences of the polarization–electric field (P–E), strain–electric field (S–E) loops in poled Mn-doped 0.05Pb(Mn1/3Sb2/3)O3–0.50PbZrO3–0.45PbTiO3 ceramics have been investigated. The P–E and S–E loops are strongly asymmetric corresponding to the presence of an internal bias field Ei after poling and aging, indicating that the domain walls are strongly pinned by preferentially oriented defect dipoles formed by the acceptor dopant ions (Mn2+/Mn3+) and O2− vacancies. Whereas, the loops exhibit a tendency of changing from asymmetric shapes to normal symmetric ones with increasing electric field amplitude or decreasing frequency. Repeated electric field cycling as well as high temperature results in a similar effect. Meanwhile, the Ei reduces consequently, providing evidence of domain depinning or internal bias field relaxation. It is suggested that the reorientation of the defect dipoles and depinning of domain walls arising from high temperature or electric field cycling are responsible for this extrinsic internal bias field relaxation process.