Bulletin of Materials Science最新文献

Pure and Ni-doped CoTiO₃ powders with a nominal composition of the Co_(1–x)Ni_xTiO₃ (with x = 0.00; 0.25; 0.50 and 0.75) were prepared by mechanical milling using solid-state reaction from NiO, Co₃O₄ and TiO₂ powders as raw materials in mole ratio. The effect of Ni²⁺ doping on structural, particle morphology, elemental composition, magnetic properties and microwaves absorption characteristics of Co_(1–x)Ni_xTiO₃ was investigated by X-ray diffraction, scanning electron microscope, energy dispersive spectroscopy, Raman spectroscopy, vibration samples magnetometer and vector network analyzer, respectively. It was found that all fabricated samples show in single phase with hexagonal structure. However, with the presence of Ni²⁺ ions dopant, the particle size and saturation magnetization (M_s) values decrease, whereas the microwave absorption capability increases.

The dielectric properties and AC conductivity behaviour of yttrium strontium silicate oxy-apatite (YSSO) compounds substituted with europium ions as rare earth, Y_8–xSr₂(SiO₄)₆O₂: xEu, x = 0, 0.10, 0.15, 0.20, 0.25 and 0.30 mol% (YSSO: xEu), prepared by solution combustion method has been reported here. The XRD and Rietveld refinement patterns confirmed the formation of a hexagonal closed-packed structure with space group P6₃/m and space group number 176. The morphological analysis was carried out by scanning electron microscopy, which showed random distribution of particles. The elemental analysis was done by EDXS, which gave the atomic% and weight% of all the initial elements present in the compound. The frequency- and temperature-dependent dielectric parameters (dielectric loss and dielectric constant) of the compounds have been carried out from 100 Hz to 100 kHz and from 50 to 500°C. Both of the dielectric parameters showed a decreasing trend with an increase in frequency. The highest dielectric loss value at a temperature of 500°C was obtained at ~4 for the undoped YSSO compound, and it reduced to ~1 after doping with x = 0.15 mol% of Eu³⁺ in YSSO: xEu compound. Impedance spectroscopy showed that the impedance values decreased with increasing frequency, resulting in an increase in electrical conductivity. The Nyquist plot indicated that the resistance contribution is dominant from the grain boundary effect and also, the NTCR behaviour of YSSO: xEu compounds was observed. The obtained low activation energy values (~0.04 eV) and low dielectric loss (~0.01–0.06) in high frequency across a broad temperature range indicate that the YSSO: xEu oxy-apatites can be used as paraelectric capacitors, electric power loss component, etc.

By applying non-equilibrium green’s function (NEGF) formalism combined with density functional theory (DFT), this study aims to investigate and compare the electron transport properties of tetracene molecules anchored with C₂₀, C₂₄ and C₂₈ fullerene molecules. The results indicate that tetracene molecule exhibits metallic behaviour with C₂₀ anchors, whereas C₂₄ and C₂₈ fullerenes, respectively, show semi-metallic and non-metallic nature. Various attributes such as transmission spectrum, density of states (DOS), molecular projected self-consistent Hamiltonian (MPSH) eigen states, conductance and current characteristics conclude that shifting of the molecular orbitals with variations in the bias voltage determines the current spectrum. The nonlinearity in the I–V curve and troughs in the G–V curve are attributed to the transitions seen in the active molecular orbitals, resulting in a variation in the HOMO–LUMO gap. Further, a multifunctional behaviour showing a clear negative differential resistance region with peak-to-valley current ratio of 1.70 and rectifying performance with a rectification ratio of 1.45 in the case of C₂₀–tetracene–C₂₀ molecular junction is observed. These results will pave a new road map for developing versatile molecular devices with targeted properties.

Due to environmental health concerns, the usage of toxic lead (Pb) based alloys in electronic applcations has been strictly banned. Thus, Pb-free solders are noted as potential alloys in electronic industries to replace Pb-based solders. Sn–Cu (Pb-free solder) alloy has attracted wide attention. However, investigations on the effect of cooling modes on tribological properties of tin–copper (Sn–Cu) solder are scant. Usually, the mode of solidification controls the grain structure of alloys and, hence, the mechanical properties. Better hardness (mechanical) and wear (tribological) properties are essential for the higher reliability of Sn–Cu alloy in real working applications, such as in aerospace avionics and electronic systems. Hence in the current research study, an effect of grain morphology, hardness and wear properties were assessed for the Sn–Cu alloy cooled in different moulds (copper and graphite around oil).

An approximate solution to the position-dependent effective mass one-dimensional Schrödinger equation was obtained using the BenDaniel and Duke technique under a Morse potential. The modelling was conducted in a GaAsSb-based valence-band quantum well to investigate the combined effects of non-resonant intense laser fields and externally applied electric fields. For the first time, the spatial dependence of the effective mass of a heavy hole was estimated relative to the Morse geometry of the confinement potential. The Schrödinger equation was solved to examine the electronic bound states and the corresponding wave functions using the Finite Element Method, incorporating the Kramers–Henneberger transformation and the Floquet method. Utilizing the density matrix formalism, the linear and third-order nonlinear optical responses were evaluated by calculating light absorption coefficients and refractive index changes under externally applied laser and electric fields. The electronic studies revealed that the laser-dressed confinement effects were diminished in the presence of a positive electric field, while enhanced confinement effects were observed when the laser-dressed quantum well was exposed to a negative electric field. Additionally, the laser-dressed optical responses were found to be red-shifted with a positive electric field and blue-shifted with a negative electric field.

This article describes a new synthesis of nanoscaled Y₂O₃ that is bioinspired. It has been confirmed that Callistemon viminalis flower extract works well as a chelator when used to bioengineer high-shape anisotropy nanorods of single-phase Y₂O₃. X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, fourier transform infrared spectroscopy and photoluminescence spectroscopy were used to analyse the structural, morphological, surface and optical features. The photoluminescent spectra of the bio-engineered nanorods show blue emissions. As the annealing temperature was increased from 300 to 500°C, the blue colour purity values of the synthesized Y₂O₃ nanorods were 58.1, 80.7 and 77.0% at 300, 400 and 500°C respectively. The chromaticity coordinates (0.2020, 0.1931), (0.1660, 0.1082) and (0.1714, 0.1226) from the photoluminescence spectra of the biosynthesized Y₂O₃ nanorods were used to determine these values. The CIE y-component coordinate values of the bioengineered blue-emitting nanophosphors suggest their potential for applications in display technology and white light-emitting diodes.

The application of fluorescent small molecules is greatly limited because they tend to photobleach and cause potential harm to organisms. However, SiO₂ with fluorescent properties can be obtained by incorporating fluorescent small molecules into the preparation process using Stöber’s method. In this study, we successfully synthesized and prepared nanosized SiO₂ spheres doped with sodium fluorescein (FS). The resulting fluorescent material exhibited excellent optical properties similar to FS and demonstrated good optical stability. Additionally, the surface of SiO₂ spheres was easily modified, allowing for the introduction of foreign groups or small molecules. By incorporating 4-dimethylaminobenzoic acid (DBA), the final FS@SiO₂@DBA fluorescent material enhanced the affinity for latent fingerprints. The use of FS@SiO₂@DBA composites for latent fingerprint development demonstrated significant development effects on various substrates, including slides, metal locks, rough marble, galvanized iron sheets, quartz crucibles and blue plastic housings. These findings suggest that FS@SiO₂@DBA has a significant impact on latent fingerprint development.

Advanced composites are increasingly used in aircraft and automotive structures, highlighting the need to address delamination, a critical failure mode caused by interlaminar weakness. Also the end-of-life of composite material is challenging. The interlaminar fracture toughness, impact resistance and residual flexural performance of glass/epoxy composites with recycled milled carbon fibre (rmCF) and recycled milled Kevlar fibre (rmKF) fillers are examined in this study. This novel approach blends recycled fillers (rmBF) and tests their effects on interlaminar fracture toughness, crash performance, and residual strength using modes I, II, mixed mode I/II and drop weight impact tests. Filler-loaded samples show a remarkable increase in fracture toughness, with initiation improvements of 319, 31 and 200% and propagation improvements of 83, 14.4 and 172.3% in modes I, II and mixed mode. Up to 15% improvement was seen in the impact performance index and a 10% increase in residual strength. FTIR is used to correlate the effects of rmCF, rmKF and rmBF on interfacial properties, while SEM micrographs show how the filler-modified matrix toughens interlaminar fractures. This research helps improve composite material performance and sustainability.

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In this study, the effect of resin-filler ratio on the physical, mechanical and durability properties of polymer composites was investigated. Iron-manganese (IM) aggregate was used as filling material. Within the study, polymer composite samples were produced using six different resin-filler ratios (15–85%, 20–80%, 25–75%, 30–70%, 35–65% and 40–60%). The specimens were examined and tested for apparent density, water absorption, porosity, ultrasonic pulse velocity (UPV), compressive strength, flexural strength, freeze-thaw (FT) cycles and compressive strength after sulphate impact. The results obtained showed that the resin-fill ratio had a significant effect on the homogeneous distribution of aggregates. While structural integrity could not be achieved when the resin content was below 15%, significant segregation problems occurred when the resin content was above 40%. It was also determined that the increase in resin ratio led to a decrease in apparent density, water absorption and porosity values, while increasing UPV, compressive strength, flexural strength and durability properties. Additionally, FTIR analysis revealed similar vibration peaks across all composite samples. In the P35IM65 and P40IM60 samples, the increased polyester content filled the gaps between the IM aggregates, resulting in a more cohesive matrix-aggregate interface. Optimizing the resin/filler ratio is a complex process that requires a careful balance to meet the varying requirements for mechanical properties, durability and structural integrity. In this study, the optimal resin-filler ratio for ensuring the structural integrity of the aggregates was determined to be 15:85, while the most effective ratio for enhancing mechanical properties and durability was found to be 40:60.

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Recycled aluminium alloys are increasingly favoured for their environmental and economic benefits; however, maintaining and enhancing their mechanical properties is critical. In this study, we investigate the mechanical and microstructural properties of recycled LM25 aluminium alloys modified with additions chromium (Cr). The introduction of Cr as a modifier is explored to enhance the strength and structural integrity of LM25 alloys, which are widely used in automotive applications. Scraps were recycled to form LM25 alloys, and chromium was added in powdered form at predetermined levels, followed by mechanical testing, wear, corrosion analysis, and microstructural analysis using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The results reveal a significant improvement in tensile strength and hardness with the addition of Cr, attributed to refined microstructures and the formation of stable intermetallic phases. Furthermore, the microstructural analysis indicated a notable reduction in grain size and a more uniform phase distribution in Cr-modified alloys. The Cr modification enhances the wear and corrosion resistance of the LM25 alloy by forming a passive barrier. These findings underscore the potential of Cr as an effective alloying element in recycled LM25 aluminium alloys, contributing to improved performance characteristics suitable for demanding applications.