Material Characterization, Materials Processing, Impedance Spectroscopy, Materials Scanning Electron Microscopy, XRD Analysis, X-ray Diffraction Single Crystal, Thin Films, and Nanotechnology, Microwave, Material Characteristics, Impedance Magnetoelectrics,Multiferroics, magnetodielectrics,
56
Scopus Publications
Scopus Publications
Modulating Energy Storage Properties in Three-Layered Perovskite Ceramics via Defect Engineering Mechanism Mahmoud S. Alkathy, Vitor F. Barbosa, Flavio Paulo Milton, Rodrigo A. R. Carvalho, Rafael Alves Lozano, et al. Journal of Materials Science Materials in Electronics, 2026 Materials with high phase temperatures are considered among the most promising modern energy storage materials. This is due to their thermal stability, low dielectric loss, and ability to maintain energy density under harsh conditions. In line with these qualities, this research focused on how adding La 3+ , Co 3+ , and Fe 3+ ions to three-layered Aurivillius-phase ceramics affects their dielectric capacitor properties. The co-doped ceramics exhibited a recoverable energy density ( W rec ) of 0.224 J/cm 3 and an energy efficiency ( η ) of 83%. This is a huge improvement compared to the undoped sample, which had a (W rec ) of 0.053 J/cm 3 and an energy efficiency ( η ) of 7%. The enhancement is attributed to the formation of defect dipoles formed by associations between oxygen vacancies and transition metal ions. These defect dipoles generate internal fields that stabilize the polarization and pin domain walls, thereby improving the energy storage performance. Structural analysis reveals that substituting Ti with Co/Fe induces oxygen vacancies and octahedral tilting, thereby significantly diminishing hysteresis. Scanning electron microscopy data demonstrate a reduction in grain size, decreasing from 2.236 to 1.92 μ m. Conversely, temperature-dependent investigations demonstrated a reduction in the Curie temperature ( T c ), specifically from 493 to 387 °C, while maintaining polarization stability up to 300 °C. X-ray photoelectron spectroscopy (XPS) data revealed an increase in the concentration of oxygen vacancies, rising from 11.6% to 23.8%, thus supporting the suggested defect mechanism. These observations imply that Aurivillius ceramics, designed with defects and tri-doped, possess the potential for high-performance dielectric energy storage applications at elevated temperatures.
Correlation of Structural Properties and Ferroelectricity in Cobalt and Iron Co-Doped Aurivillius Ceramics Based on Rietveld Refinement Analysis Mahmoud. S. Alkathy, Vitor F Barbosa, Ricardo Pereira Bonini, Marcio Daldin Teodoro, Fabio. L. Zabotto, et al. Crystal Research and Technology, 2025 This research examines the structural and ferroelectric characteristics of lanthanum‐modified Bismuth Titanate (Bi4Ti3O12) ceramics by co‐doping with cobalt (Co3+) and iron (Fe3+). Structural refinement demonstrates that the La3+ substitution at Bi3+ significantly decreases titanium–oxygen bond lengths, augmenting the covalent character crucial for altering the ferroelectric response. Incorporating Co3⁺ and Fe3⁺ induces defects, causing a reduction in maximum polarization from around 10 µC cm−2 to about 4.88 µC cm−2. Structural examinations indicate an orthorhombicity of around 7.64×10−3 in the BLaT sample and 7.49×10−3 in the BLaT‐FC2 sample, corresponding with their respective polarization tendencies. A defect pinning hindered the motion of the domain wall in BLaT‐FC2, resulting in a constricted (P–E) hysteresis loop. Nevertheless, repeated electrical cycling enhances ferroelectric responses, allowing greater polarization alignment through progressive defect mitigation. As a result, structural defects and functional properties are dynamically interacting. The results highlight the significant impact of defect dynamics and structural changes on controlling the ferroelectric performance of Bi‐based layered structure ceramics. This indicates that deliberate doping strategies and defect engineering can substantially enhance the reliability and effectiveness of ferroelectric materials for advanced electronic applications.
Synthesis and high-frequency magnetoelectric characterization of the 0-3 particulate lead-free multiferroic composite KNN/CFO Alexandre José Gualdi, Leonardo Dos Santos Batacline, Gustavo Correia Espírito Santo, Mahmoud S Alkathy, Fabio Luis Zabotto Journal of Physics Condensed Matter, 2024 The research for lead-free magnetoelectric (ME) multiferroic composite materials has increased considerably because they are environmentally friendly. For composites with 0–3 connectivity, synthesis with lead-free phase has proven challenging to obtain high values of ME coupling. This work reports the successful synthesis of the KNN/CFO composite (K0.5N0.5NbO3/CoFe2O4) by conventional synthesis process. XRD and SEI showed two well-defined, also presenting good electric polarization values. The ME coefficient was very high, reaching values close to 2850 mV cm−1·Oe at the electromechanical resonance frequency. The dipolar interaction between the electric charges and magnetic moments of the KNN and CFO phases was responsible for the high value and the behavior of dependence on the applied magnetic field.
