Study of incommensurate phases in lanthanum-doped zirconium-rich lead zirconate titanate ceramics

The microstructure and nanostructure of zirconium-rich Pb(Zr,Ti)O(3) ceramics doped with small amounts of La which are right at transition between the ferroelectric (FE) and antiferroelectric (AFE) orderings has been examined using Transmission Electron Microscopy (TEM) imaging and diffraction. In this region, the La doping frustrates the formation of simple FE or AFE phases and promotes long period ordered phases (2-3 nm) with ordering along < 110 > with unit cells incommensurate with the primitive cubic unit cell. We show that the domain structure in these materials is closely related to that previously observed in AFE PbZrO(3). Moreover, precision measurements of crystallographic tilts at domain boundaries using Kikuchi diffraction methods also confirms the close relationship to PbZrO(3). The domains also contain a nanostructure perpendicular to the long-period ordering direction, but the reasons for the appearance of this nanostructure remain unclear

Electrocaloric effect and freezing temperature in (Pb0.8Ba0.2)[(Zn1∕3Nb2∕3)0.7Ti0.3]O3 relaxor ferroelectric ceramic

The electrocaloric effect (ECE) is studied in (Pb0.8Ba0.2)[(Zn1∕3Nb2∕3)0.7Ti0.3]O3 relaxor ferroelectric ceramic by using an “indirect method”. The electric dependence for the polarization (hysteresis loops) has been obtained for several temperatures showing typical relaxor characteristics. The temperature change ΔT, which is associated with the ECE, is calculated by using the temperature dependence for the polarization. A maximum value for ΔT is observed for temperatures close above the freezing temperature, showing an indirect evidence of that critical temperature. The results are discussed considering the contribution of the polar nanoregions to the polarization

Incorporation of dysprosium ions into PbTiO3 ferroelectric ceramic system

A structural analysis concerning the incorporation of dysprosium into A- and/or B-sites of the lead titanate is shown. The two "boundary" refinements are presented, i.e., Dy2+ substitutes for Pb2+ (Dy3+ substitutes for Ti4+) and Dy3+ substitutes for Pb2+ (Dy3+ substitutes for Ti4+). The results offer quantitative information about the incorporation into both crystallographic sites. The increase of Dy3+ fraction into B-site provides the increase of the Ti4+ atomic displacement along the [001] direction and the tetragonal distortion

Switching and energy-storage characteristics in PLZT 2/95/5 antiferroelectric ceramic system

Switching mechanisms and energy-storage properties have been investigated in (Pb0.98La0.02)(Zr0.95Ti0.05)0.995O3 antiferroelectric ceramics. The electric field dependence of polarization (P–E hysteresis loops) indicates that both the ferroelectric (FE) and antiferroelectric (AFE) phases coexist, being the AFE more stable above 100∘C. It has been observed that the temperature has an important influence on the switching parameters. On the other hand, the energy-storage density, which has been calculated from the P–E hysteresis loops, shows values higher than 1J/cm3 for temperatures above 100∘C with around 73% of efficiency as average. These properties indicate that the studied ceramic system reveals as a promising AFE material for energy-storage devices application