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.

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.

Photonic crystal (PhC) has been studied for their potential to improve the efficiency of Cu₂ZnSnS₄ solar cells by increasing the generated photocurrent by integrating it as a back reflector with almost zero transmission through the absorption active zone of the solar cell. It was found that the thickness of PhC layers greatly affects the width of the photonic bandgap and that increasing the thickness of VO₂ causes it to shift to a higher wavelength range. The PhC layers were added at the back side of the solar cell in two different configurations: (Monoclinic (M) VO₂/TiO₂) and (Tetragonal (T) VO₂/TiO₂) via SCAPS model. The study found that the (M VO₂/TiO₂) configuration led to an enhancement of the device's efficiency from 11.02 to 12.79%, while the (T VO₂/TiO₂) reaches 16.88%. The study concluded that the PhC layers enhance the light-matter coupling and photonic coupling and improvement in the device's performance.

Artificial periodic structures drew a lot of attention because of their ability to be built with novel acoustic features. A novel nanostructured phononic superlattice (NPhS) based two-dimensional multilayer structure as a high-sensitive multichannel liquid sensor that provided bright multichannel band gap windows has been introduced. Theoretically, the designed structure is composed of [(MoS₂/PtSe₂)⁴] NPhS with a cavity filled with different concentrations of Ethylene Glycol at room temperature toward acoustic bandgap engineering multichannel sensor. We examined the interaction of acoustic waves with nano and bulk phononic superlattice (PhS) structures. In addition, we studied the effect of using different analyte layer thicknesses on the resonance peaks that appeared inside the band gaps. Many sharp resonance peaks appeared in multi-band gaps, which introduced high sensitivity, Q-factor, and figure of merit (FOM) values for each concentration of Ethylene Glycol. Furthermore, the effect of resonance peaks' full width at half maximum (FWHM) on the Q-factor of the NPhS multichannel sensor has been studied. From our results, the relation between the sensitivity of our multichannel sensor and the resonance frequency of each concentration shows a linear behavior. The highest sensitivity was obtained for a 1.00 m% concentration of 0.21 (GHz/(kg/m³)) at a resonance frequency value of 0.21 THz. In addition, the NPhS multichannel sensor recorded the highest Q-factor for 0.8069 m% with a value of 1744 and the highest FOM for 0.3819 m% with a value of 0.05988 (m³/kg). Moreover, we studied the effect of temperature on the sensitivity of the NPhS multichannel sensor. We showed the highest sensitivity value of 1.79 (GHz/^o C) at 10 °C towards Ethylene Glycol. Further, the dispersion relation of an acoustic wave propagating inside perfect and defected nano and bulk PhS structures has been introduced. Our proposed multichannel liquid sensor can introduce a novel sensitivity at Terahertz frequency ranges.

Studying the mechanical properties mismatching of SnSe₂/ZrS₂ 2D materials with Voigt-Reuss-Hill (VRH) schemes promise a novel structure for sensing applications. For the first time, we studied the effect of mechanical mismatching properties of SnSe₂/ZrS₂ multilayers with VRH schemes on the acoustic wave's propagation through acoustic superlattice (AS). We proposed [(SnSe₂/ZrS₂)⁴] superlattice with VRH schemes as a new THz multichannel sensor for acetonitrile sensing. The [(SnSe₂/ZrS₂)⁴] with Voigt scheme introduced several resonant peaks for acetonitrile inside the superlattice bandgap compared to Hill and Reuss schemes. The appropriate relation between resonance frequency shift and resonance bandwidth is the key to improving the multichannel sensor's sensitivity to liquid characteristics. Further, we studied the effect of low and high temperatures on our multichannel sensor. Furthermore, the highest sensitivity and resonance frequency were recorded by our AS with the Voigt scheme towards acetonitrile having values of 0.287 (GHz/(kg/m³)) and 0.237 THz at 0 °C. The results show a novel sensitivity of acetonitrile for low-temperature environments.

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%).