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This study explores the synthesis and characterization of Fe-doped CaTiO3 compounds via the Pechini method, focusing on their structural, magnetic, and electrical properties. Notably, a previously unreported magnetic property is observed in the Fe-doped CaTiO3 compound. Despite significant structural distortions, ferroelectric polarization is identified using the Geometrical Polarization Approach (GPA), indicating its emergent nature. These distortions are attributed to robust chemical bonds between ionic O1−2 and Ti+4 sites, as evidenced by electronic density maps. This research sheds light on the potential of these materials for various technological applications. [ABSTRACT FROM AUTHOR]

Perovskites have been pointed out as promising candidates for several technologic areas, especially for photovoltaic applications. In this work, CaTiO3 compounds were synthesized by using the Pechini method and their structural, optical, and electrical properties were investigated. Tilted octahedral oxygen arrangements with a single center of symmetry for positive and negative electric charges are observed, forming a nonpolar perovskite structure. The origin of the observed structural distortions is directly linked to the strongest chemical bond between the O1−2 and Ti+4 ions. Direct (2.9 eV) and indirect (3.8 eV) optical band gaps are also observed. [ABSTRACT FROM AUTHOR]

In this work, the nanostructuration effects on the physical properties of pure and La doped (0.6)BiFeO3‐(0.4)PbTiO3 magnetoelectric nanoparticles were investigated. An exotic magnetic response, mimicking a superparamagneticlike behavior that raised the magnetization to levels never reported before for these materials, is clearly observed. Another important change associated with the nanostructuration is observed in the symmetry of the perovskite-structured materials, which changes from a tetragonal to a rhombohedral one. Transmission electron microscopic and X-ray diffraction results (investigated by the Debye-Scherrer method) revealed uniform nanoparticles of spherical shape, average particle sizes close to 5 nm and with a single structural domain (only one crystallite per particle). The pronounced increase (∼20 times) in the magnetization response of the nanoparticles, compared to microparticle ones, is observed in magnetization curves. A magnetic semiempirical phenomenological model, where noninteracting single-domain magnetic nanoparticles are considered, is used to fit the magnetization curves, revealing the almost absence of surface effects in a typical superparamagneticlike behavior. All these aspects pointing to a material with immense potential for practical applications in spintronics and magnetoelectronics. [ABSTRACT FROM AUTHOR]

In this manuscript, X-ray and high-resolution neutron powder diffraction investigations, associated with Rietveld refinements, magnetic hysteresis curves and a modeling of electron-density distributions around the ions, are used to describe the driving forces responsible for tuning the ferroic states in La doped (0.6)BiFeO3-(0.4)PbTiO3 compositions. The intrinsic relations between the ferroic orders and the structural arrangements (angles, distances and electron-density distributions around the ions) are revealed, helping in the understanding of some aspects comprising the ferroic properties of perovskite-based displacive multiferroic compounds. [ABSTRACT FROM AUTHOR]

In this article, the Finite Element Method was applied to investigate the magnetic and electrical responses of laminar composites based on TbxDy1−xFe2 (TERFENOL-D) and PbZrxTi1−xO3 (PZT). The simulations show that the laminar composites at the so-called 2-2 connectivity provide a substantial magnetoelectric response when excited by superimposed DC and AC magnetic fields. It is found that the output signal is optimized for AC magnetic fields whose frequencies match with some of that vibration (harmonics) modes of the piezoelectric layer. [ABSTRACT FROM AUTHOR]

BiFeO3 nanoparticles (<200 nm) were synthesized using the Pechini method and submitted to structural, microstructural, magnetic and electrical investigations. Two different structural symmetries were proposed to describe the BiFeO3 structure and the observed electrical properties, rhombohedral (R3c space group) and orthorhombic (Pbmn). Electric conductivity results obtained as a function of temperature, show two completely reversible changes in the baseline (310 °C and 385 °C), indicating two magnetic corresponding transitions associated with the orthorhombic and rhombohedral symmetries. These transitions were linked to predicted insulating-metal transition when magnetic arrangement changes from antiferromagnetic to a nonmagnetic ordering. [ABSTRACT FROM AUTHOR]

In this manuscript, microstructural, structural and magnetic properties of pure and La doped (0.6)BiFeO3-(0.4)PbTiO3 polycrystals were investigated. X-ray diffraction, transmission and scanning electron microscopy results reveal morphologically uniform particles of rhombohedral and rhombohedral/tetragonal symmetries for pure and La doped samples. An enhanced magnetization, characterized by slim loop hysteretic curves of null remnant magnetization and 2 emu/g saturation (15 kOe) magnetization, is observed at room temperature for samples with average particle size close to 5 nm. [ABSTRACT FROM AUTHOR]

In this manuscript, an innovative and bioactive polyvinylidene fluoride-biphasic calcium phosphate (PVDF-BCP) ferroelectric composite was synthesized and characterized. FTIR investigations reveal that our synthesis method promotes a deep change in the PVDF structure, leading to the emergency of the ferroelectric polar β-PVDF phase in the PVDF-BCP composite. Microstructural analyzes performed in samples immersed in simulated body fluid reveal an elevated growth rate of synthetic osseous tissue (apatite, ∼15 μm in 7 days) on the composite surface, attesting its enhanced bioactivity. The observation of ferroelectric hysteresis loops attests the polar character of the obtained PVDF-BCP composites. [ABSTRACT FROM AUTHOR]

Copyright of Ceramica is the property of Associacao Brasileira de Ceramica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ceramica is the property of Associacao Brasileira de Ceramica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Piezoelectric transformers are devices able to raise an electrical input voltage with low energy losses. However, there are a few reports on the designing of multiferroic piezoelectric transformers. In this paper, an alternative bi-layer radial mode piezoelectric/magnetoelectric transformer approach by using a Nb doped (1 wt%) Pb(Zr)53Ti47O3piezoelectric ceramic as actuator, and a La doped (5 wt%) (0.6)BiFeO3-(0.4)PbTiO3magnetoelectric ceramic as transducer has been tested. The voltage gain and the efficiency were determined as a function of the frequency and the load test resistance. A typical response, characteristic of bi-layered radial mode solid-state transformer, with a voltage gain of 2.5 at a load resistance of 7 kΩ, and an efficiency of 0.15 at load resistance 1 kΩ, were obtained. The results showed the feasibility of such multiferroic transformer for some practical smart and multifunctional devices applications. [ABSTRACT FROM AUTHOR]

This contribution presents an alternative synthesis route to produce highly resistive BiFeO3multiferroic samples. The use of a fast sintering process followed by quenching to room temperature resulted in ceramic bulks with a resistance higher than 1012Ohm.m at room temperature. In addition, anomalies found in the dielectric and resistivity characterization indicated the presence of magnetoelectric coupling in the synthesized BiFeO3sample. [ABSTRACT FROM AUTHOR]

In this paper, three well-known prototypic ferroic materials, BaTiO3, PbZr0.4Ti0.6O3and Fe3O4, were experimentally and theoretically investigated to explore the origin of their respective ferroic state. Their structural properties were determined by X-ray powder diffraction and Rietveld refinement. The electron density distribution around cationic and anionic sites were obtained by using the Maximum Entropy Method on analyzing the X-ray diffraction results. Electron density distributions and the electronic band structures were determined by Density Functional Theory simulations using experimental and refined structural parameters as input data. The results show a strong correspondence for all the obtained properties and features, suggesting the important role of structural aspects and chemical bonding in the stabilization of the ferroic states in each studied system. [ABSTRACT FROM AUTHOR]

Copyright of Ceramica is the property of Associacao Brasileira de Ceramica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The lead-free AlFeO3-based compounds are attractive multiferroic materials, as those present piezoelectricity and ferrimagnetism at low temperatures. In this work the synthesis and ferroic properties of AlFeO3-based ceramics were investigated. Stoichiometric proportions of the precursors - α-Fe2O3and α-Al2O3- were milled and sintered to obtain AlFeO3ceramics. Also, AlFeO3ceramics doped with 2at% of Nb2O5or MnO2were sintered in oxygen flow at 1700 K. The crystal structure of the samples was studied by X-ray diffraction. The diffractograms were refined by the Rietveld method. The results obtained from refinements showed an orthorhombic symmetry with space groupPna21. Dielectric, ferroelectric and magnetic investigations suggested a magnetoelectric coupling between the electric and magnetic orderings at temperatures below ∼ 160 K for AlFeO3, Al(Fe0.98Nb0.02)O3and Al(Fe0.98Mn0.02)O3, where the compositions show the ferromagnetic and ferroelectric ordering. [ABSTRACT FROM AUTHOR]

The origin of enhanced ferroism in La-modified BiFeO3-PbTiO3 compounds is investigated by examining chemical bonding in high-resolution structural measurements. It is shown that structural modifications in the perovskite A-site, such as absent or inactive lone-pair ions, lead to reduced covalence in A-O bonds and increased covalence in B-O bonds for the tetragonal phase. This change in bond character results in a structural accommodation that favors the rhombohedral over the tetragonal phase, which also enhances the ferroic properties. These observations highlight the influence of modifiers on BiFeO3-PbTiO3 bonds and phase stabilization mechanisms. [ABSTRACT FROM AUTHOR]

Structural, ferroelectric, and magnetic arrangements, and electron density in the vicinity of cations, were modeled from high-resolution X-ray and neutron powder diffraction data in La modified BiFeO3-PbTiO3 compounds. Important features for controlling the intrinsic mechanism for the magnetoelectric coupling in these materials, as prototypes for perovskite structured magnetoelectric multiferroics, are pointed out and discussed. It is shown that the magnetoelectric coupling angle is governed by covalent-like forces, which also affect the structural and ferroelectric distortions in the unit cell. [ABSTRACT FROM AUTHOR]

In this paper, the microscopic mechanism for structural, ferroelectric, and magnetic stabilities in displacive perovskite structured multiferroics is investigated by studying BiFeO3-PbTiO3 solid solutions. The results revealed that thermal stability and ferroic orders are intimately connected with the changes in A and B perovskite sites. The breakdown mechanism of the cycloidal magnetic network, which permits to observe the resulting macroscopic magnetization is reveled, compared, and presented for various compositions of the BiFeO3-PbTiO3 system. The delicate energetic balance that stabilizes the electrically polar structures in displacive perovskite multiferroics is proposed and it was showed that it is fully connected to the configuration (atomic occupancy and formal ionic charge) of each individual site of the perovskite unit cell. [ABSTRACT FROM AUTHOR]

The potentialities of BiFeO3-PbTiO3 multiferroic compounds for magnetic-field sensing applications is investigated by characterizing the dynamical magnetoelectric response of La doped (0.6)BiFeO3-(0.4)PbTiO3 piezoceramics. The results are compared with those obtained in Nb doped (1 wt. %) PbZr0.53Ti0.47O3 (PZT-5A) piezoceramics and the observed non-linearity of the oscillating voltage response of (0.6)BiFeO3-(0.4)PbTiO3 piezoceramics is attributed to the overlapping of the intrinsic and extrinsic magnetoelectric effects that were successfully decoupled by analyzing the in-phase and out-of-phase voltage components relative to applied oscillating magnetic field. For an alternating cosine-like magnetic field of 0.32 Oe, at the piezoelectric resonance frequency (184.2 kHz), the alternating voltage response decreases from 7.77 mV, at -10 kOe, to 2.71 mV, at 1.8 kOe, to subsequently increases until 5.97 mV at 10 kOe. This non-linear voltage response, which can be easily converted into a linear signal by using the phase difference, can be used for static magnetic field sensing in a wide range of magnetic fields. [ABSTRACT FROM AUTHOR]

In this paper, the relationship between ferroic states and the physicochemical mechanism which governs the (Bi/Pb/La)-O bonds in polycrystalline La doped (0.6)BiFeO3-(0.4)PbTiO3 compounds were investigated. An abrupt change in the symmetries of perovskite-structured samples, from tetragonal (P4mm) to rhombohedral (R3c), occurs with the increase of the La concentration, highlighting the diminishment of the hybridization of the (Bi/Pb)-O bonds when La is added into the solid solution, and the emergence of a characteristic morphotropic phase boundary tuned by doping. A maximum remnant polarization (10 μC/cm2) was observed for low La concentrations (where R3c and P4mm phases coexist), while the maximum remnant magnetization (∼75 × 10-3 emu/g) was observed for highly La concentrated samples. These results show that ferroelectric and weak-ferromagnetic orders are strongly correlated to the structural arrangement, which in turn are directly related to the chemical A-O and B-O bonds (long-range and short-range forces) and with the chemical characteristics of the elements that fulfills the A site of the perovskite structure. [ABSTRACT FROM AUTHOR]