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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]

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]

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.)

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]

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]

Polyvinylidene fluoride - hydroxyapatite composite filaments were processed by twin-screw extrusion at different processing angular velocities and characterized by scanning electron and atomic force microscopies, differential scanning calorimetry and tensile tests. Polymer-ceramic composites with a 0-3 connectivity were successfully obtained. Regardless of the used processing parameters, all composite filaments present very similar melting (∼152°C) and solidification (∼139°C) points and elastic moduli (∼1.0 GPa) for hydroxyapatite as dispersed phase in the composite with concentrations up to 25 wt%, indicating that they are adequate for twin-screw extrusion and 3D printing. However, the yield strength (∼29 MPa), ultimate tensile strength (∼36 MPa) and tensile point (∼29 MPa) parameters are similar only for hydroxyapatite concentrations up to 15 wt%, once higher concentrations of hydroxyapatite as dispersed phase result in fragile samples (∼50% lower for each studied property)., (Copyright © 2021 Elsevier Ltd. All rights reserved.)