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    Development of Yttrium-Doped BaTiO3 for Next-Generation Multilayer Ceramic Capacitors
    (Amer Chemical Soc, 2023) Tihtih, Mohammed; Ibrahim, Jamal Eldin F. M.; Basyooni, Mohamed A.; En-nadir, Redouane; Belaid, Walid; Hussainova, Irina; Kocserha, Istvan
    The use of electronic devices that incorporate multilayer ceramic capacitors (MLCCs) is on the rise, requiring materials with good electrical properties and a narrow band gap. This study synthesized yttrium-substituted barium titanate (Ba1-xYxTiO3, BYT) using a sol-gel process at 950 degrees C with varying concentrations of yttrium (0 < x < 0.3). X-ray diffraction analysis showed that the tetragonal phase became less pronounced as the yttrium content increased. The samples had varying grain sizes and porosity, with the BY30%T sample having the narrowest band gap at 2.21 eV. The BYT ceramic with 30% yttrium had a thermal conductivity of up to 7 W/m K and an electrical conductivity down to 0.002 (omega cm)-1 at 180 degrees C. The current-voltage characteristics of the BYT MLCC were also studied, showing potential use in next-generation high-capacity MLCCs. This work presents BYT as a promising material for these types of capacitors.
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    Functionality and Activity of Sol-Gel-Prepared Co and Fe co-Doped Lead-Free BTO for Thermo-Optical Applications
    (Amer Chemical Soc, 2023) Tihtih, Mohammed; Ibrahim, Jamal Eldin F. M.; Basyooni, Mohamed A.; En-nadir, Redouane; Hussainova, Irina; Kocserha, Istvan
    The BTO, BFTC, and BCTF compounds were synthesized by the sol- gel method. The XRD study revealed the formation of single-phase tetragonal perovskite structures with the space group (P4mm). The crystalline parameters were studied as a function of Fe and Co contents and occupation of Ba and/or Ti sites by Fe and Co in the BTO lattice. It was found that the obtained strain increases when Ba2+ is substituted by Co2+ and Ti4+ by Fe3+. The Raman investigation confirmed the existence of three active modes (B1/E (TO1LO), (E (TO)/A1(TO3), and (A 1(LO)/E (TO), all of which are related to the existence of the tetragonal phase and strongly support the XRD results. The microstructural study showed a clear correlation between the presence of Fe and Co and the grain size distribution. Optical studies revealed the improvement in band gap energy with transition-metal (Fe and Co) co-doped BTO ceramics. The decrease in the band gap is explained by the competing effects of Columbian interactions, microdeformation, and oxygen defects. The results indicate that the presence of Fe and Co dopants enhances the absorption in the BTO ceramic. The dopants demonstrated an effect on thermal conductivity: they decreased the thermal conductivity of BTO, which is in the range of 0.76-2.23 W m(-1) K-1 at room temperature and 2.02-0.27 W m(-1) K-1 at elevated temperatures. The microstructure of the manufactured materials and the grain size distribution affect the compressive strength.
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    Role of A-site (Sr), B-site (Y), and A, B sites (Sr, Y) substitution in lead-free BaTiO3 ceramic compounds: Structural, optical, microstructure, mechanical, and thermal conductivity properties
    (Elsevier, 2023) Tihtih, Mohammed; Ibrahim, Jamal Eldin F. M.; Basyooni, Mohamed A.; Kurovics, Emese; Belaid, Walid; Hussainova, Irina; Kocserha, Istvan
    Strontium and Yttrium-doped and co-doped BaTiO3 (BT) ceramics with the stoichiometric formulas BaTiO3, B1-xSrxTiO3, Ba1-xYxTiO3, BaTi1-xYxO3, Ba1-xYxTi1-xYxO3, and Ba1-xSrxTi1-xYxO3 (x = 0.075) noted as BT, BSrT, BYT, BTY, BYTY, and BSrTY have been synthesized through sol-gel method. X-ray diffraction (XRD) patterns of the prepared ceramics, calcined at a slightly low temperature (950 degrees C/3h), displayed that BT, BSrT, and BYT ceramics possess tetragonal structures and BTY, BYTY, and BSrTY have a cubic structure. The incorporation of the Ba and/or Ti sites by Sr2+ and Y3+ ions in the lattice of BaTiO3 ceramic and the behaviors of the crystalline characteristics in terms of the Y and Sr dopant were described in detail. The scanning electron microscopy (SEM) images demonstrated that the densification and grain size were strongly related to Sr and Y elements. UV-visible spectroscopy was used to study the optical behavior of the as-prepared ceramic samples and revealed that Sr and Y dopants reduce the optical band gap energy to 2.74 eV for the BSrTY compound. The outcomes also demonstrated that the levels of Urbach energy are indicative of the created disorder following the inclusion of Yttrium. The measurements of the thermal conductivity indicated the influence of the doping mechanism on the thermal conductivity results of the synthesized samples. Indeed, the thermal conductivity of BaTiO3 is decreased with Sr and Y dopants and found to be in the range of 085-2.23 W.m(-1). K-1 at room temperature and decreases slightly with increasing temperature from 2.02 to 0.73-W.m(-1). K-1. Moreover, the microstructure and grains distribution of the BT, BSrT, BYT, BTY, BYTY, and BSrTY samples impacted the compressive strength, hence; the compressive strength was minimized as the grain size decreased.
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    Structural, optical, and electronic properties of barium titanate: experiment characterisation and first-principles study
    (Taylor & Francis Ltd, 2022) Tihtih, Mohammed; Ibrahim, Jamal Eldin F. M.; Basyooni, Mohamed A.; Belaid, Walid; Gomze, Laszlo A.; Kocserha, Istvan
    To study the structural, electronic, and optical properties of lead-free Barium titanate BaTiO3 (BT) ferroelectric material in its tetragonal structure, a combination of experimental and theoretical studies has been used and the obtained results were discussed. The studied BT compound was prepared via the sol-gel technique. The calculated bandgap energy (E-g) and structural parameters of BT are determined using four types of exchange-correlation functionals (PBE, PBEsol, LDA, and PW91) in the perspective of the density functional theory (DFT). XRD and Raman analysis have shown that BT ceramic exhibits a tetragonal phase structure without any trace of impurity phases. The UV-vis investigation showed that BT has a bandgap energy of 3.19 eV, which is larger than the theoretically calculated values. The computed lattice parameter c is overestimated (as large as similar to 1% deviation) when using the LDA approximation. In contrast, PBEsol proved that those lattice constants were close to the experimental values (a deviation of less than 1%).