Field and Frequency Dependence of the Dynamic Hysteresis in Lead Zirconate Titanate Solid Solutions.

Dynamic hysteresis of Nb-doped Pb( Zr1− x Ti x) O3 ( PZT, 0.20 ≤ x ≤ 0.60) ceramics were studied systemically at different field ( E) and frequency ( f). The hysteresis loops were strongly dependent on E and f. The measured coercive fields ( Ec0) were far lower than the calculated values based on the Landau-Ginzburg theory, and increased dramatically from the rhombohedral phase to the tetragonal phase while had less variation with composition in the same phase. With increasing E or f for each composition, three types of loops were observed: linear, minor, and saturated loops. The cross fields ( E0), cross polarizations ( P0), and hysteresis areas ( <A>) showed different variation regularities with f. Similar varying curves were observed for all PZT ceramic samples by normalizing E0, P0, and <A> with E/Ec0, which indicated the same polarization switching for different domain structures. Further analyses revealed that the switching processes can be divided into three stages: space charge polarization, domain switching, and steady state. The first and second stage occurred at ~0.5 and ~1.5 E/ Ec0, respectively. These results would be very helpful to further understand the polarization switching of ferroelectric ceramics. [ABSTRACT FROM AUTHOR]