Bulletin of Materials Science最新文献

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.

This study is aimed to have an understanding of the formation of silicon vacancy (SiV) colour centres in diamond during thin film growth of diamond in microwave plasma CVD reactor. The study focusses on different sources of silicon impurities in the chamber and the possibility of controlling the formation of SiV during growth for various applications. Diamond thin films were grown on different substrates and their photoluminescence (PL) spectra were analysed to understand the role of substrate material and residual silicon in the chamber for the formation of SiVs. The predominant contribution to SiV formation was found to be the residual silicon in the chamber originating from the quartz components exposed to the plasma. In the films grown on silicon substrate, there is also substrate contribution to the PL signal. Controlling the formation of SiVs in polycrystalline diamond can pave the way to optically integrate SiVs to different photonic structures.

This study introduces a method for producing environmentally friendly peelable film using prevulcanized rubber latex, offering a simple and cost-effective solution capable of covering complex shapes. The synthesis investigation explores the relationship between conventional rubber formulations and the film’s performance, highlighting the significance of selecting appropriate chemicals to improve functionality. Key considerations for selecting the latex compound formulation include the solution's properties, particularly focussing on flow behaviour and coating time, as well as the mechanical properties, fire resistance, peel ability and durability of the resulting film under challenging conditions. The primary investigation into the impact of the zinc diethyldithiocarbamate : sulphur (ZDEC : S) ratio on crosslink density provides insight into rheological and mechanical properties. Furthermore, the addition of phenol, 4-methyl-, reaction products with dicyclopentadiene and isobutene (CPL) as an antioxidant improves heat resistance and oxygen tolerance. The remarkable versatility of peelable film allows for its application through various methods, including sagging (1–10 s^–1), painting and spraying (10–100 s^–1), effectively protecting against dust, scratches and temperatures exceeding 200°C. Particularly noteworthy are its low peel force of 0.139 N, 44 mm removal path and 2-month service life. The findings from testing the crucial properties of the manufactured films, which meets industrial standards, indicate a pathway to produce environmentally sustainable products, with a strong potential for further advancement towards commercial production.

Owing to the increasing demands of high-density data storage double-halide perovskite-based resistive random access memory (RRAM) have recently emerged as a promising candidate in the forefront of next-generation optoelectronic memory applications. The ionic motion-based quick switching is the key feature of this kind of material, which plays a significant role in resistive switching (RS) applications. Recently, lead-free tin-based double-halide perovskites have been considered as favourable material due to their superior stability, functionality and eco-friendly nature. Here, we report the synthesis of cesium tin (IV) iodide (Cs₂SnI₆) perovskites. X-ray diffraction (XRD) pattern of the as-synthesized perovskite confirms the formation of Cs₂SnI₆ material. The crystallographic data corroborate the formation of a pure cubic phase, free of any other phase at room temperature. We also studied optical properties of the sample by using the ultraviolet–visible (UV) spectra and photoluminescence (PL) spectra. A broadband at around 580 nm is observed in the UV−Vis absorption spectra. The optical band gap of the sample is found to be 1.68 eV. Cs₂SnI₆ perovskite exhibited intense PL emission at ~540 nm. In this work, to fabricate a flexible Al/Cs₂SnI₆/ITO-PET memory device, we used Cs₂SnI₆ film as a switching layer and the device exhibits bipolar RS characteristics.