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(Bi1–xLaxFeO3)0.5(PbTiO3)0.5solid solution obtained by mechanochemical synthesis was characterized by X-ray diffraction (XRD), atomic force microscopy and Fourier transform near-infrared Raman spectroscopy. The single-phase solid solution with La content betweenx= 0 and 0.5 was prepared. The solid solution exhibits a tetragonal symmetryP4mmfor 0 ≤x≤ 0.2. It was found that Raman spectra undergo a significant change for the solid solution with La content betweenx= 0.16 and 0.20. It may indicate the existence of a morphotropic boundary in this range of the La content. Detailed XRD study on (Bi0.5La0.5FeO3)0.5(PbTiO3)0.5pointed to a rhombohedral symmetryR3c. [ABSTRACT FROM AUTHOR]

In this article, we present results of field cooled (FC) and zero field cooled (ZFC) magnetization measurements and investigation of aging and memory effect in bismuth ferrite (BFO) multiferroic micro-cubes obtained by means of simple microwave synthesis procedure. It is found that difference between FC and ZFC magnetizations appear at the temperature of freezing of ferromagnetic domain walls. The decay of the magnetic momentversustime described by power-law relation and the absence of memory effect are caused by domain growth mechanism rather than by the spin-glass phase. The negligible value of remnant magnetic moment indicates that BFO compound exhibits low concentration of ferromagnetic domains and can be close to ferromagnetic to spin-glass transition. [ABSTRACT FROM PUBLISHER]

Local resistive switching was observed using AFM equipped with conducting tip addressing ∼15 unit cells in high-quality BiFeO3single crystal grown from a non-stoichiometric melt. The switching appeared under high-vacuum conditions above 340 K and the studies at various temperatures yield the activation energy of 0.74 eV. The field-induced changes in the resistivity were ascribed to the presence of localized oxygen vacancies as a consequence of the mixed valence of Fe2+/Fe3+ions. [ABSTRACT FROM AUTHOR]

K 1- x Na x NbO 3 is considered as an alternative system for lead-based functional ceramics widely used in transducers, sensors and actuators. In some applications however, the composites of electroactive ceramic and polymer, with low acoustic impedance and dielectric permittivity that can be tailored to various requirement, are more useful. We studied dielectric relaxation processes in polyvinylidene fluoride (PVDF) loaded with K 0.5 Na 0.5 NbO 3 powder in wide temperature and frequency range. The powder was prepared by solid state synthesis and characterized by HRTEM and NIR Raman spectroscopy. The dielectric response of (K 0.5 Na 0.5 NbO 3 ) 0.32 (PVDF) 0.68 composite, of (0–3) connectivity, was found to be determined by the relaxation processes of the polymer matrix with an additional broad low-frequency anomaly at ∼⃒ 305 K that we relate to a response of water absorbed by the shell of KNN grains. [ABSTRACT FROM AUTHOR]

Relaxor-like dielectric response was observed in ferroelectric P(VDF/TrFE)(50/50) films irradiated with 1.0 and 1.5 MeV electrons and related to the results of ESR, IR and NIR Raman studies of radiation damage of the copolymer. The origin of the strong dielectric dispersion below the permittivity maximum and the frequency dependence of the temperature of ℇ max is rather complex: radiation-induced downward shift of the Curie point results in an overlapping of the dielectric anomalies at T C and at the glass transition and moreover, the dispersion is enhanced by the contribution of polar clusters consisting in short-range coherence of trans conformations. The single and conjugated C=C bonds, appearing as a result of the decay of free radicals created by incident electrons, cut ferroelectric all-trans conformation of the copolymer chains into polar clusters of short trans coherence. [ABSTRACT FROM AUTHOR]

Dielectric response (100 Hz-1 MHz) and pyroelectric response (light modulation frequency range 10 Hz-1 kHz) of ferroelectric P(VDF/TrFE)(50/50) copolymer loaded with relaxor PLZT 9.5/65/35 ceramic powder of 10 nm crystallite size and ∼700 nm aggregates was studied. Though the dielectric permittivity of the composites increases due to high permittivity of the ceramic, their dielectric response is determined by dielectric relaxation processes of the polymer matrix. The dispersive dielectric anomalies of PLZT-0.9/65/35 relaxor ceramic affect mainly the dielectric absorption of the composites in the range of dipolar relaxation in the crystallite phase of the copolymer. The composites exhibit pyroelectric activity proper for application in operation frequency up to 1 kHz and temperature range 290-310 K. [ABSTRACT FROM AUTHOR]

The article discusses various reports published within the issue. Articles published within the issue were taken from the XVII Czech -- Polish Seminar held in Znojmo, Czech Republic on May 22-26, 2006. The topics covered include the physics of the ferroelectrics and relaxor ferroelectrics with perovskite structure as well as phase transitions, aspects of ferroelectricity and structural phase transitions.