Ebtesam El Farhatey

The current research is concerned with the structure, morphology, and physical properties of a double perovskite La2FeCrO6. The crystallite size of the sample was determined to be 22.46 nm using the modified Scherrer equation. The elemental composition of La2FeCrO6 was confirmed through X-ray photoelectron-spectroscopy (XPS), which detected La, Fe, Cr, and oxygen, as well as oxygen deficiencies that significantly impact the observed ferroelectric behavior in the investigated sample. High-resolution transmission electron microscopy (HRTEM) verified the nanoscale preparation of the sample with an average particle size of 33.32 nm. Thermogravimetric analysis (TGA) was employed to investigate the thermal properties of the sample including the calculation of thermodynamic functions such as changes in enthalpy (ΔH) and entropy (ΔS) for La2FeCrO6. The material exhibits an optical direct transition with a band gap value of 3.4 eV and an Urbach energy of 2.5 eV. Due to its large specific surface area and band gap value, La2FeCrO6 shows promise in applications such as photocatalysis and water purification. The ac conductivity of La2FeCrO6 follows the universal dielectric response (UDR), and the P-E loop of the sample demonstrates its ferroelectric behavior.

A novel core/shell nanoferrite material has been developed for use in various potential applications. Rare-earth doped calcium-ferrite with the compositional formula $$\text{Ca}{\text{Fe}}_{1.925}{\text{Sm}}_{0.05}{\text{Gd}}_{0.025}{\text O}_4$$ was prepared as a core using the citrate auto-combustion method before being coated with PVA as a polymeric shell. High crystalline and single-phase orthorhombic nanoparticles are confirmed by XR-D (X-ray diffraction). An estimate has been made for the mean size of the crystal structures by analyzing the broadening of XR-D lines within a range of 20 nanometers. HR-TEM (high-resolution tunnelling electron microscope) micrographs also showed that the particles had an orthorhombic shape with well-defined boundaries. EDX (energy-dispersive X-ray) and FT-IR were used to investigate the elemental constitution and the molecular structure of samples. The dielectric properties were discussed in the basics of interfacial polarization and Koop`s model. The anti-ferromagnetic nature of the samples was identified by a VSM (vibrating sample magnetometer). The proposed composition was found to improve the electromagnetic absorption performance, which was confirmed with the measurements of optical parameters from the absorbance spectrum recorded by the UV–VIS–NIR spectroscope. The optical band-gap and Urbach energies of the synthesized samples have been investigated, in addition to the refractive index and the extinction coefficient. The Wemple-DiDomenico oscillator model was used to examine the dispersion energies.

Barium titanate materials are currently a special topic for scientific research due to their effective technological applications. The tetragonal BaTi1-xZrxO3 (0.0 ≤ x ≤ 0.3) nanoparticles (NPs) were synthesized using a modified citrate technique. The current work provides a comparative approach for the calculation of crystallite size, stress, strain, and elastic characteristics based on X-ray diffraction (XRD) patterns. Various models have been developed to analyze XRD data; these models differ in their assumptions, mathematical approaches, and the type of information they provide. The Scherrer model ignores lattice micro-structures that develop in nanostructures, such as intrinsic strain. To overcome such drawbacks, three Williamson-Hall models, (the uniform deformation model (UDM)), the uniform stress deformation model (USDM), and the uniform deformation energy density model (UDEDM) have been discussed. According to the USDM model, with increasing Zr ion concentrations, interplanar space increases, causing a drop in Young’s modulus. All the previous approaches take into account the diffraction angle (2θ)-dependent peak broadening, which is thought to represent a combination of size and strain-driven induced broadening.

Standard SiMo ductile cast iron automotive alloys are typically subjected to various hostile environmental conditions. For the current investigation, SiMo with a silicon content of 5% and molybdenum contents ranging from 0 to 1.5% was used. In two corrosive environments of 0.6 M NaCl and 0.5 M H2SO4, the study intends to present the corrosion behavior of high silicon molybdenum ductile cast iron (SiMo). Moreover, the impact of changing Mo on the microstructural characteristics has been investigated. The SEM-EDX examinations revealed that the nodule counts, M6C carbides, and lamellar pearlite increased while the ferritic matrix decreased with increasing Mo contents. It is clear that the addition of Mo reduces cast iron's rate of corrosion and thus increases its corrosion resistance. The results showed that SiMo cast iron alloy with 1.0 wt% Mo had a lower corrosion current (Icorr) in 0.6 M NaCl solution while lower corrosion current (Icorr) with the cast iron containing 1.5 wt% Mo in 0.5 M H2SO4 solution, which resulted in the lowest corrosion rate. The occurrence of a galvanic couple between the alloy matrix and the graphite nodules results in electrochemical corrosion, with the largest corrosion rates taking place at Mo-free alloy in both media.

In the current study, we developed a simple and biocompatible method for producing core–shell nanoparticles (NPs). Citrate auto combustion and green procedures were used to create core–shell Ag/CoGd0.025Er0.05Fe1.925O4 (Ag/CGEFO) sample with an average crystallite size of 26.84 nm. The prepared samples were characterized via different structural techniques, such as x-ray diffraction (XRD), Raman Spectroscopy (RS), High-Resolution Transmission Electron Microscopy, and Energy Dispersive x-ray analysis. These analyses were utilized to characterize and confirm the successful formation of the core–shell architecture. For core–shell NPs, all peaks of Ag and CGEFO ferrite are detected in the XRD, confirming the co-presence of the ferrite spinel phase and the cubic Ag phase. The magnetic hysteresis curves demonstrate typical hard ferri-magnetic behavior along with maximum magnetic saturation values up to 53.74 emu g−1 for the CGEFO sample, while an enhanced coercivity is detected for the coated sample. Moreover, the width of the hysteresis loop is increased for the Ag/CGEFO sample compared to the uncoated one. This indicates that the addition of Ag as a shell increases magneto crystalline anisotropy. Moreover, the E g of uncoated CGEFO is equal to 1.4 eV, increasing to 3.6 eV for coated ones. This implies the influence of CGEFO is diminished when the surface is coated with Ag (shell), and the reflectance of the Ag/CGEFO core–shell is nearly dependent on the reflectance of the Ag shell layer. Consequently, the Ag/CGEFO can be used as a light shielding substance.

High-silicon and molybdenum (SiMo) ductile iron is a common heat-resistant alloy that may be exposed to high-temperature wear during service in many of its applications. The wear behavior of four SiMo ductile iron alloys was evaluated at different temperatures up to 750 °C. This research focuses on the influence of various Mo contents on the microstructure, structural stability, and hence, the wear performance of such alloys. Thermodynamic calculations proposed the phase diagrams, critical transformation temperatures, and phase volume fractions in all samples by means of Thermo-Calc software. The dilatometry measurements were carried for confirming the theoretical results of Thermo-Calc thermodynamic calculations. The results revealed that the microstructure of SiMo ductile cast iron consists of nodular graphite and a ferrite matrix with carbides embedded in the fine precipitates at the grain boundary regions. The type of carbides and the nature of these fine precipitates are discussed according to EDX and SEM results. Adding molybdenum enhanced the wear performance of SiMo by decreasing the weight loss by about 40–70% compared to a Mo-free alloy. This is due to the increased molybdenum carbides, which increase hardness and improve wear resistance in SiMo alloys. The high temperatures have a negative effect on reducing the wear resistance at 250 °C. On the other hand, the wear resistance unexpectedly started to increase at higher temperatures of 500 °C and 750 °C because of the contribution of oxidative wear with abrasive wear by forming a protective oxide layer. Furthermore, the obtained results supported the idea that adding molybdenum improves wear resistance at high temperatures. Hence, SiMo has the potential to be wear-resistant material in wider applications requiring high-temperature wear resistance.