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Phase transitions and field-induced preferred orientation in (Pb 1-x La x )(Zr 0.90 Ti 0.10 ) 1–x/4 O 3 (PLZT x/90/10) ceramics upon electric field cycling using in situ X-ray diffraction were studied. The evolution of the {200} pc and {111} pc diffraction line profiles indicate that PLZT 4/90/10 and PLZT 3/90/10 compositions undergo an antiferroelectric (AFE)–ferroelectric (FE) phase switching. Both PLZT 4/90/10 and PLZT 3/90/10 exhibit irreversible preferred orientation after experiencing the field-induced AFE-to-FE phase switching. An electric field-induced structure develops in both compositions which has a reversible character during the field decreasing in PLZT 4/90/10 and an irreversible character in PLZT 3/90/10. In addition, structural analysis of pre-poled PLZT 3/90/10 ceramics show that it is possible to induce consecutive FE-to-AFE and AFE-to-FE transitions when fields of reversed polarity are applied in sequence. The field range required to induce the AFE phase is broad, and the phase transition is kinetically slow. This kind of transition has rarely been reported before. [ABSTRACT FROM AUTHOR]

Abstract: Diphase magnetoelectric composites of CoFe2O4–Pb(ZrTi)O3 were prepared by citrate–nitrate combustion technique by using Pb(Zr,Ti)O3 template powders obtained by the mixed oxide method. Pure diphase powder composites with a good crystallinity were obtained after calcination. The composition and purity were maintained after sintering at temperature of 1100°C/2h, which ensured limited reactions at interfaces, while by sintering at 1250°C/2h, some small amounts of secondary phases identified as nonstoichiometric ZrO2−x resulted. The method allowed to produce diphase ceramics with homogeneous microstructures and a very good mixing of the two phases. The dielectric and magnetic investigation at room temperature confirmed the formation of composite ceramics with both dielectric and magnetic properties at room temperature, with permittivity and magnetization resulted as sum properties from the parent Pb(Zr,Ti)O3 and ferrite phases. [Copyright &y& Elsevier]

Abstract: The First Order Reversal Curves (FORC) diagrams method is proposed for the characterization of the switching process and ac-tunability in BaZr0.10Ti0.90O3 ceramics prepared via solid state reaction. The properties induced by different microstructures, having two extreme grain sizes of 0.75 and 3.3μm are investigated by monitoring the changes of the FORC diagrams. The maximum of FORC distribution is located at low fields independently on the grain size and no clear separation between the reversible/irreversible contributions to the polarization are found. A higher degree of the local inhomogeneity is characteristic to the fine ceramic. The FORC susceptibility related to the ac-tunability determined on the major hysteresis loop is very sensitive to the grain size: it is much smaller in the fine material, due to the pinning of the domain walls by different types of defective areas. [Copyright &y& Elsevier]