Bulletin of Materials Science最新文献

Improvement in mechanical properties of fibre-reinforced polymer composites through proper matrix modification has emerged as the significant trend in recent advanced technology. Dispersion of nanofillers in the matrix results in ultra-light weight, high strength, impact resistant and durable structures. In the current investigation, effect of the addition of varying percentages (0, 1, 3, 5 and 7 wt.%) of low-cost nanoclay to the unsymmetrical carbon/glass (C₂G₈) hybrid composites on mechanical, tribological and low-velocity impact (LVI) behaviour were investigated. Using traditional hand lay-up techniques, nanocomposite specimens were prepared. The results revealed that C₂G₈ hybrid composite with 5 wt.% loading of nanoclay possessed maximum hardness (35 HV), flexural strength (494 MPa), impact strength (Izod (119.022 kJ m⁻²), Charpy (563.922 kJ m⁻²)) and minimum specific wear rate (19.6 × 10⁻³ mm³ Nm⁻¹) in comparison with other hybrid combinations. LVI test also revealed enhanced energy absorption (112.46 J) for hybrid nanocomposite against plain C₂G₈ hybrid composite. Furthermore, the damage depth and areas were observed by visual inspection and scanning electron microscope to account for best possible structure–property relationship. Developed hybrid nanocomposite may be considered as a suitable material for various automotive applications.

In this investigation, we employ density functional theory with the generalized gradient approximation of Wu–Cohen and the modified Beck–Johnson approach. Our focus is on examining the structural, electronic and thermodynamic properties of ternary chalcopyrite CdXP₂ (X: Si and Sn) compounds. Our computed results of ternary structures for structural properties, for instance, tetragonal distortion, equilibrium lattice constants and bond lengths, show good agreement with the available results of the experimental and theoretical calculations. Our calculated positive results of cohesive energy and negative values of the formation energies of the title materials show their thermodynamic stability as well as highlight their possible experimental fabrication at these concentrations. From band structure calculations, it is found that the energy bandgap is of direct nature at Γ–Γ symmetry points for both ternary and quaternary alloys; however, the width of the bandgap is found to be decreased with increasing Sn concentration in the CdSi_1–xSn_xP₂ alloys. Moreover, thermodynamic properties using the quasi-harmonic Debye model are also computed. Our study provides a platform for further experimental and theoretical investigations to expose the potential of these materials for their applications.

Nanofilm CdS@Cd/Si heterojunctions have been fabricated by a two-step method. The obvious rectification effect can be observed. However, the leakage current density is relatively large. According to the criterion for judging the conduction model, three conduction mechanisms can be observed, which are the thermally generated electrons model, the Ohmic model and the space-charge-limited-current model from low voltage to high voltage, respectively. The preparation process of nanofilm CdS@Cd/Si heterojunctions by this two-step method, which directly grows nanofilm CdS@Cd on the silicon substrate to construct heterojunctions, can reduce the introduction of excessive defects and facilitate the release of stress in the interface.

In the present study, we have developed molybdenum diselenide (MoSe₂) nanosheets via an effective hydrothermal process by varying synthesis temperatures in a high-yield production. XRD results illustrate that all the products indexed to a hexagonal crystal phase of MoSe₂ (2H-MoSe₂) with crystallite sizes around 7 nm. TEM and HRTEM images confirmed a high-quality crystalline feature of MoSe₂ nanosheets. Interestingly, the identified interplanar spacing of 0.61 nm corresponds to a well-organized atomic-scale arrangement with (hkil: 0002) plane of 2H-MoSe₂ crystal. Additionally, Moiré fringes of different periodicities are clearly visible in some crystalline regions suggesting that MoSe₂ nanosheets are well crystallized. The selected area electron diffraction patterns elucidate ring-like diffraction patterns indicating the polycrystalline nature of all the prepared MoSe₂ nanosheets. UV–Vis absorption spectra scrutinize the mechanism for photo-response phenomenon and the observed excitonic peaks evidently demonstrate that the synthesized MoSe₂ is in a semiconducting 2H phase with an optical bandgap ranging from 1.78 to 1.93 eV. Moreover, MoSe₂ nanosheets possess a prominent methylene blue (MB) dye adsorption capacity of 50–70% and 54–83% in lower and higher adsorption times, respectively. In a nutshell, this study reveals the potential environmental application in the adsorption of organic dye MB in wastewater of hydrothermally produced MoSe₂ nanosheets with structural and optical properties.

Design and development of novel high entropy alloys (HEAs) having balance magnetic properties with other functional properties are vital for industrial applications of these alloys. In this study, a novel Co₃₅Cr₅Fe₁₀Ni₃₀Ti₅Al₁₅ HEA was synthesized through mechanical alloying and studied for phase evolution and its effects on magnetic properties with annealing at different temperatures. As-synthesized HEA has a major fcc phase with minor concentrations of bcc and R phases. The as-synthesized HEA is also annealed at different temperatures of 500, 700 and 900°C and found that the phase identity of formed phases maintained after annealing. However, for HEA annealed at 1000°C, slight amount of new σ-phase has formed along with initial phases. Values of M_s and H_c were found to be 75 emu g⁻¹ and 18 Oe for as-synthesized Co₃₅Cr₅Fe₁₀Ni₃₀Ti₅Al₁₅ HEA. We found that after annealing at different temperatures, magnetic properties of Co₃₅Cr₅Fe₁₀Ni₃₀Ti₅Al₁₅ HEA show significant improvement. Co₃₅Cr₅Fe₁₀Ni₃₀Ti₅Al₁₅ HEA annealed at 900°C exhibited good soft magnetic characteristics with high M_s (99 emu g⁻¹), low values of H_c (3.8 Oe) and M_r (0.45 emu g⁻¹), as compared to other samples developed in the present study. Thus, designed and developed 900°C annealed Co₃₅Cr₅Fe₁₀Ni₃₀Ti₅Al₁₅ HEA can be further used for magnetic switching applications due to the high value of M_s and low value of M_r.

Barium strontium titanate (BST) is a perovskite material, which is used directly in various applications including thermistors, electromechanical actuators, sensors and ceramic capacitors. Here, we have investigated the impact of dopant (Mn and Co) on synthesized BST nanoparticles and its morphological, structural, vibrational and optical properties have been investigated through scanning electron microscopy (SEM), X-ray diffraction (XRD), photoluminescence (PL), FTIR and Raman spectroscopies. SEM image showed the nearly spherical grain for pure BST and doped (Mn and Co) BST samples. The estimated particles were strongly influenced by different dopants, in addition, Mn-doped BST showed maximum grain growth for pure and Co-doped BST samples. XRD patterns have been employed to investigate the microstructural parameters (phase, lattice, crystallite size, strain, dislocation density, etc.). The crystallite sizes have been estimated using the Scherrer formula, showing maximum crystallite size for Mn-doped BST ceramics. Recorded FTIR spectra showed the transmission peak, which is centred at wavenumber of 470 cm⁻¹ (pure BST), was shifted to 1250 cm⁻¹ with Mn-doped BST. Raman spectra exhibited the increased number of modes from pure BST to Mn-doped BST sample. PL showed the emissions bands, which were observed at 602–659 nm. Here, the peak shifted towards higher wavelength from pure BST to Mn-doped BST (red shifting from pure to Mn-doped BST). It revealed that the prepared samples can be employed as suitable photoluminar material.

Cd_0.4Zn_0.6S:r-GO composite thin film semiconductor is prepared by the process of layer by layer deposition of cadmium zinc sulphide (Cd_0.4Zn_0.6S) and reduced graphene oxide (r-GO) on Si-substrate by DIP-coating technique. In this process, initially, aqueous solution of Cd_0.4Zn_0.6S is deposited on Si-substrate (Cd_0.4Zn_0.6S/Si) and baked at 500°C temperature, then, aqueous solution of r-GO is deposited on (Cd_0.4Zn_0.6S/Si) and baked at the same temperature to fabricate (r-GO/Cd_0.4Zn_0.6S/Si) composite thin film semiconductors. Structural/electronic/electrical/magnetic properties of (Cd_0.4Zn_0.6S:r-GO)/Si composite thin film semiconductor is enhanced in the vicinity of interfacial defects, impurities, density of states with exchange of metallic/non-metallic ions (Cd²⁺/Zn²⁺)/(S²⁻, SO₃²⁻) along with the incorporation of different O-functional radicals that immigrate from r-GO. It is expected that the Cd_0.4Zn_0.6S:r-GO composite thin film semiconductor is capable of providing future promising optoelectronic as well as magnetic device-based applications.

Sustainable production of multifunctional nanomaterials is a key challenge for their widespread use. Phytochemical-assisted synthesis provides an environmentally benign route of nanoparticle modifications towards desired applications. Herein, Catharanthus roseus (CR) leaves extract has been used as a phytochemical modifier for copper oxide-doped yttrium oxide nanoparticles (CuO/Y₂O₃ NPs). The composition, structure, morphology and functional groups of CuO/Y₂O₃ NPs have been extensively modulated via green synthesis. The excellent antibacterial activities against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) pathogens suggest an increasing rate of antibacterial behaviour. Besides, the sheet-like morphology of CuO/Y₂O₃ NPs promotes photocatalytic activities by methylene blue, phenol and methyl orange degradation under sunlight with rates of 0.0203, 0.0152 and 0.0167 min⁻¹. Most importantly, CuO/Y₂O₃ NPs facilitate low oxidation peak potential (−0.58 V), extended frequency linear range (1–300 nM), and ultralow detection limit (up to 0.58 nM) for an important biomarker threonine, which is the best among any nanomaterials reported till date. Such achievement paved the way for sustainable nanomaterial modifications towards multifunctionality.

The heat-treatment process exerts a substantial influence on both the quantity and morphology of reversed austenite in 17-4PH stainless steel. In this study, the effects of different ageing treatment methods on the microstructure and corrosion resistance of the steel were investigated. Through the observation of microscopic morphology, it was found that adjustment and ageing treatment and double ageing treatment were more conducive to the migration of elements in the steel than single ageing treatment, and they also improved the microstructure. In addition to improving the uniformity of alloy element distribution, uniformity also controls the reversed austenite content. By controlling the content and distribution of reversed austenite, the stability of the corrosion film formed at the interface can be improved, thereby improving the corrosion resistance of stainless steel. The stainless steel, after adjustment treatment and ageing treatment, has better corrosion resistance. The electrochemical corrosion resistance in a high-temperature and high-pressure underground environment was evaluated based on parameters including passivation current density and passivation potential. The results revealed a significant improvement of 50.5% in electrochemical corrosion resistance and a remarkable increase of 45.96% in pitting corrosion resistance. Furthermore, the FeCl₃ pitting test demonstrated a substantial decrease of 63.16% in pitting density and a reduction of 27.96% in the uniform corrosion rate.

Electron and positron chemical potentials, positron affinity and bulk lifetime, positronium work function and positron effective mass have been computed for Zn_xCd_1−xS using a pseudo-potential approach within the virtual crystal approximation (VCA) and the independent particle model. A correction to VCA is included taking into consideration the disorder effect. This has permitted the computation of the positron affinity to separate materials of interest. The performances indicated that the positron annihilates differently in CdS than in ZnS. The bulk lifetime of positron has been obtained as 241.17 ps for CdS and 215.47 ps for ZnS. Hence, it decreases when going from CdS to ZnS. The positronium work function increases from 2.245 to 3.08 eV when augmenting the composition x from 0 to 1, indicating that only fewer positronium atoms are figured in a specimen surface and ejected for the vacuum. The positron effective mass augments from 0.96 to 1.34 m₀ when going from CdS to ZnS materials. The details collected from the assisted investigation are of a former significance for an ameliorate accordance of positron annihilation in Zn_xCd_1−xS.