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 (Ba_1-xY_xTiO₃, BYT) using a sol-gel process at 950 °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 (Ω cm)⁻¹ at 180 °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.

Strontium and Yttrium-doped and co-doped BaTiO₃ (BT) ceramics with the stoichiometric formulas BaTiO₃, B_1-xSr_xTiO₃, Ba_1-xY_xTiO₃, BaTi_1-xY_xO₃, Ba_1-xY_xTi_1-xY_xO₃, and Ba_1-xSr_xTi_1-xY_xO₃ (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 °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.

This study explored the efficient utilization of natural zeolite tuff and aluminum dross for making porous ceramic bricks, aiming to address environmental damage from waste disposal. Different compositions of these materials were used to create six batches of bricks, followed by heat treatment at varying temperatures (950–1150 °C). The raw materials and the sintered samples were analyzed using various characterization techniques. The results showed that bricks incorporating 30 % aluminum dross and sintered at 1150 °C had the lowest thermal conductivity of 0.3 W/m·K. On the other hand, bricks containing 20 % aluminum dross and sintered at the same temperature exhibited the highest compressive strength (58 MPa), a bulk density of 1.9 g/cm³, and a water absorption of approximately 13 %. All samples exceeded the minimum compressive strength requirements. This study demonstrates the feasibility of using natural zeolite tuff and aluminum dross to develop composite bricks, providing an effective waste disposal solution for sustainable development and reduced environmental pollution.

The present research examines the development of new porous ceramic bricks from Hungarian zeolitic tuff and tea waste as building materials. Recycling waste materials as a pore-forming agent in brick-making is a promising solution to environmental and economic challenges. Several zeolitic tuff/tea waste admixtures were milled in the planetary ball milling to produce homogenous powders. The substitution ratios were maintained as 0 %, 2 %, 4 %, 6 %, 8 %, 10 %, and 12 % by wt of zeolitic tuff. The ceramic disks were produced from the prepared mixtures via dry pressing and sintering at various temperatures (950–1250 °C) for consolidation. The produced bricks were investigated based on bulk density, apparent porosity, water absorption, volume shrinkage, thermal conductivity and compressive strength, as well as mineralogical, chemical, and morphological studies. The mineralogical determination confirms the existence of clinoptilolite, montmorillonite, cristobalite and illite as major phases in zeolite tuff. The experimental results reveal that the addition of tea waste produces hybrid bricks with better thermal insulation (0.17–0.504 W/m K), lighter weight (1.37–1.81 g/cm³), and lower compressive strength (5.52–34.4 MPa). However, the compressive strength value still lies within the range required by the standards. The production of burned bricks containing up to 10 wt% tea waste is viable without causing major changes in their technical characteristics. Developing new porous bricks using waste materials can help expand the application of sustainable and cost-effective insulation bricks in the construction industry.

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.

Porous mullite-based ceramics have been developed using a mixture of zeolite-poor rock and alumina through mechanical activation and reactive sintering. The experimental findings demonstrate that the in-situ mullite growth may develop in a variety of shapes, including whiskers, nanofiber, nanonetwork and diamond-like particles. The XRD examination indicates that the samples sintered at 1500 °C are mostly made of the mullite phase. The SEM photographs show that as the sintering temperature increases, the mullitization process takes place first in zeolite-poor rock particles, and subsequently, alumina combines with the silica-containing phase via a liquid-phase sintering mechanism to produce an interlocking network of extended secondary mullite. The effects of mullite formation and the sintering temperature on various properties of the sintered samples, such as their density, apparent porosity, thermal conductivity, strength, wear resistance, composition, morphologies, and microstructural characteristics of the sintered samples were studied. Increasing the sintering temperature from 1100 to 1500 °C improved the different properties. The density increased from 1.9 to 2.1 g/cm³, thermal conductivity rose from 0.9 to 1.6 W/m.K, compressive strength escalated from 18.9 to 92.1 MPa, and worn material volume decreased from 2444 to 36.9 mm³ after a 5-min abrasion test.

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 ~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%).