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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 work, we have studied the microscopic, ferroelectric, magnetic and microstructural characteristics of cobalt ferrite/barium titanate core–shell magnetoelectric nanocomposites. Magnetoelectric nanocomposites with 22 nm mean particle size were successfully obtained and observed by High Resolution Transmission Electron Microscopy and Scanning Transmission Electron Microscopy. Ferroelectric and magnetic properties were studied and confirmed by Scanning Probe Microscopy. Ferroelectric nanoregions were observed at the nanocomposites shell and magnetic nanoregions were highlighted in the nanocomposites core. Thus, magnetoelectric nanocomposites suitable for use in multifunctional biological/biomedical/bioengineering applications, as magnetic field nanosensors and other multifunctional applications were obtained. [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]

Multiferroic materials with magnetoelectric properties, due to their coupling between the electrical and magnetic properties have attracted the attention of many researchers. Perovskite structured materials based on BiFeO3 are a class of materials largely considered in these studies. In this work, Bi1-xNdxFe0.99Co0.01O3 (x = 0.05, 0.10 and 0.20) compositions were synthesized aiming a better understanding of the crystal and electronic structure role in ferroic properties of these materials. Structural studies were made by X-ray diffraction and Rietveld refinement; evidencing the rhombohedral symmetry of the samples with space group R3c. Electron density calculations were performed by the maximum entropy method. These studies showed that Nd3+ substitution causes distortions in the unit cell, which have influence on the magnetic properties. Also, the electron density maps showed the bonds between the iron and oxygen ions did not changed a lot. But the Minimum Electron Density observations were enough to conclude that the ferroelectric and the dielectric properties of Bi1-xNdxFe0.99Co0.01O3 compositions would be modified with the Nd3+ substitution. [ABSTRACT FROM AUTHOR]

In the present work the influence of milling process below 173 K (cryomilling) on the nanostructuration of BiFeO3 powders, synthesized by fast-firing thermal treatment allied to high-energy ball milling, is evaluated as function of milling time as well as balls size/mass ratio. The influence of the cryomilling process on the structural and magnetic properties of BiFeO3 powders is investigated and the key role of the crystallite size on the magnetic response is evidenced. The results show a strong nonlinear magnetic response, which is governed by the crystallite size while induced strain does not play an important role. [ABSTRACT FROM AUTHOR]

In this paper, the photocatalytic activity of bismuth ferrite particles synthesized by high-energy ball milling is evaluated by considering the degradation of methylene blue solutions. Once chemical routes are extensively used to produce these kind of photocatalytic reactors, this mechanochemical route has the advantage of large-scale and low-cost production. The structural, microstructural and optical properties of bismuth ferrite powders are investigated and the photocatalytic efficiency is experimentally proved. The results show a degradation of 95% of the methylene blue dye, which became complete after the addition of the H2O2 oxidizing agent and 15 min of illumination. [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]

The magnetoelectric materials have been being studied due to the scientific chalenges and the very promissing possibility of applications in electronic devices. BiFeO3 is room temperature single-phase multiferroic material. However there are some issues regarding conductivity and undesired parasitic phases that cause the experimentally reduced electrical polarization and low or no net magnetization in this material. In order to solve these questions we studied the effect of partial replacement of Bi3+ by Nd3+ in the Bi1-xNdxFe0.99Co0.01O3 compositions. X-ray diffraction patterns confirmed single phased rhombohedrally distorted perovskite structure in obtained ceramics. Scanning electron microscopy images reveal that the ceramic grains are almost irregular spheres with a 2 μm in diameter, and samples present equal porosity. With the increasing of the Nd3+ substitution the real part of the dielectric constant increased in almost 10 times but decreases the magnetization. As a consequence, the Bi1-xNdxFe0.99Co0.01O3 ceramics presented an induced magnetoelectric voltage and magnetodielectric effects. [ABSTRACT FROM AUTHOR]