Bulletin of Materials Science最新文献

Over the last decade, graphene's exceptional properties have revolutionized diverse fields with applications spanning electronics, materials science, energy storage, gas sensing and biotechnology (Castro Neto et al [1]). Graphene oxide (GO), derived from graphene has gained significant attention in the field of gas sensing due to its exceptional electrical, chemical and mechanical properties (Ma et al [2], Klechikov et al [3]). Modified Hummer’s method of GO synthesis is a well-known protocol wherein sonication, a powerful dispersion technique, is employed to exfoliate and functionalize GO sheets. Sonication provides the necessary energy to facilitate separation of bulk graphite oxide into thin, single- or few-layered GO nanosheets (Bera et al [4]). In this study, six GO samples synthesized at varying sonication times (5–120 min) have been investigated for H₂ and SO₂ gas sensing and their response characteristics were analyzed. The application of ultrasonic energy, leading to shear forces, reducing the lateral size of GO flakes, thus producing more uniform nanosheets, is clearly discernible. Characterizations including XRD, Raman, FTIR, TEM and UV-vis are shown to support the control influenced by sonication vis-à-vis reduction of particle size and control of flake morphology. Maximum gas sensing response characteristics were observed for GO sample that has been sonicated for 90 min. A fragmentation of the GO nanosheet along the a-axis is clearly discernible for sonication times greater than 60 minutes. It facilitates enhancement of the gas sensing response characteristics for both the gases.

The development of advanced alloys materials with tailored mechanical properties is essential for industries such as aerospace engineering. Conversely, the ability to design custom chemical compositions based on desired properties is fundamental to many industrial applications. In this research, an artificial neural network (ANN) and generative adversarial network (GAN) are proposed to predict properties and design alloys. A dataset of 4000 alloys, including the chemical composition of 45 elements, 21 different properties and 75 tempers, is created. ANN models are developed and optimized to predict key properties, demonstrating strong forecasting capabilities. Incorporating temper data into the input features significantly enhances the models’ accuracy, particularly for critical mechanical property prediction. Secondly, GAN is employed to create novel alloy compositions based on the properties and result show its limitation by proposing a unique chemical composition related to the desired properties. An optimized generative collaborative networks (OGCN) is proposed based on two successive models, a generator and a predictor model. Results show its capability to generate alternative chemical compositions that achieve desired properties, demonstrating reliability and industrial value through coherence with known functional compositions.

Magnesium aluminate (MgAl₂O₄) spinel (MAS) is a very promising synthetic material of cubic crystal structure with its excellent mechanical, thermal, chemical, dielectric and optical properties. Due to its superior high-temperature properties and eco-friendliness, it has gained importance as a refractory material for use in steel-teeming ladles, cement rotary kilns and glass tank furnaces. Apart from refractory, polycrystalline MAS is extensively used in optically transparent windows, armours and domes, owing to its high transparency with acceptable pyro-chemical properties. MAS formation from alumina and magnesia involves a volume expansion of 5–8%, which prohibits the formation of dense MAS bodies through a single-stage sintering process. As a result, a more expensive double-stage firing process is required to produce dense MAS ceramics. However, various additives play a significant role in the formation and sintering of MAS through the reaction sintering process. Research has shown that halide doping can lower the spinel formation temperature, enhance densification during sintering and modify the microstructure of MAS, resulting in a notable improvement in its thermo-mechanical properties. This review aims to explore the spinel formation and sintering characteristics of halide-doped MAS.

This research aims to analyse the physical properties of lead-free double perovskites ({text{A}}_{2} {text{GaScI}}_{6}) (where A = Li, Rb, Cs) using first-principles method. The structural stability of the considered material is confirmed through geometry optimization process which includes formation energy, octahedral tilting factor, tolerance factor and analysis of elastic parameters. The electronic properties are evaluated using both generalized gradient approximation (GGA) with Perdew–Burke–Ernzerhof (PBE) and Tran and Blaha modified Becke-Johnson (TB-mBJ) methods through analysis of the density of states and band structures to obtain accurate energy band gaps. Subsequently, the optical parameters, including the absorption coefficient, loss function, optical conductivity, reflectivity, dielectric function, and refractive index, are calculated and analyzed. The results show that all double perovskites exhibit a high absorption coefficient in the visible and UV regions. The calculated mechanical parameters indicated that studied materials are elastically stable, compressible, anisotropic and show high melting temperature. Thermoelectric parameters indicate that electrical and thermal conductivities, power factor, and seebeck coefficient all increase with temperature. The calculated ZT at 300 K is very close to unity and positive seebeck coefficient, indicating p-type behaviour. The calculated band gaps along with optical, thermoelectric and mechanical parameters envisaged that these materials are very suitable for optoelectronic and thermoelectric devices for green energy harvesting.

Within this study, pure ZnO and ZnO:Cu (10 at.% and 20 at.%) were synthesized by an efficient sol-gel method. Various physical properties were investigated using the conventional methods of energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). XRD result verified hexagonal structure of zinc oxide; however, the addition of copper, modified the main structure to some extent. The result of FESEM showed the nanosized quasi-spherical grains and the agglomeration of them. The protection factors against gamma rays, including mean free path (MFP), mass attenuation coefficients (MAC), tenth value layer (TVL), half value layer (HVL), linear attenuation coefficients (LAC) were calculated. According to these factors, it can be concluded that the use of ZnO and ZnO–Cu (10 at.% and 20 at.%) as a gamma ray protector can be useful. In addition to the experimental examination, simulation with GEANT4 simulation code was also used to examine the shielding parameters.

Using density functional theory (DFT), we investigated the effect of strain on the physical properties of Rb₂AgPCl₆. The Rb₂AgPCl₆ possesses an indirect band gap of 1.58 eV. The strain significantly tunes the electronics band gap of Rb₂AgPCl₆. We find that the band gap increases (1.79 eV)/decrease (0.86 eV) with the application of +6%/–6% strain. In addition, optical properties have shown that unstrained and strained Rb₂AgPCl₆ compounds are potential materials for optical applications in the visible spectrum. Remarkably, the tandem architecture (top-cell) needs a large bandgap and strong absorption, and the Rb₂AgPCl₆ satisfies these conditions. The narrow band gap of 0.86 eV with –6% strain strong optical absorption could make Rb₂AgPCl₆ an excellent candidate for tandem architecture in the bottom cell. Interestingly, the strain enhances the zT of Rb₂AgPCl₆ to ~0.79 at room temperature. Thus, based on our outcomes, the strained Rb₂AgPCl₆ could be favorable candidates in the optoelectronics and thermoelectric devices.

Counterfeiting of metal alloys poses a significant challenge in industries including aerospace, automotive, construction and electronics, where material integrity is critical. The infiltration of counterfeit alloys can lead to severe consequences such as product failures, safety hazards, financial losses, and damage to the reputation of legitimate manufacturers. To address this growing concern, various authentication technologies are currently employed to detect and prevent the circulation of counterfeit metals/alloys. This study introduces an innovative solution to counter the escalating threat of counterfeit metal alloys, by integrating an upconversion phosphor into a tin-lead alloy, offering a built-in, dual-layered anti-counterfeiting system. This system features both visual and auditory authentication mechanisms without compromising the alloy's functional performance. When exposed to a 980 nm light source, the material exhibits a distinctive distance-dependent multi-colour emission pattern; a vivid red glow at close range, shifting to orange at an intermediate distance, and reverting to red when viewed from farther away. In addition to visual identification, the modified alloy incorporates an additional layer of auditory authentication feature; emits a beep sound when scanned with an infrared taggant detector. Unlike conventional methods that rely on external security measures, this novel approach embeds multi-level anti-counterfeiting features directly within the alloy, enhancing security and resistance to tampering.

Graphical Abstract

Non-toxic, inorganic metal halide cubic perovskites are the standard for commercializing optoelectronic and photovoltaic devices. Owing to their major significance, a comprehensive analysis of the structural, electronic and optical properties of AlSnX₃ (X = F, Cl, Br, and I) perovskites was performed utilizing ab-initio density-functional theory. The negative formation energies verify the examined materials’ thermodynamic stability. All the compounds exhibit semiconducting behaviour, with bandgaps of 0.305, 0.205, 0.120 and 0.213 eV calculated using the GGA-PBE functional, and corresponding bandgaps of 1.034, 0.896, 0.854 and 0.902 eV obtained using the Hybrid HSE06 functional for AlSnF₃, AlSnCl₃, AlSnBr₃ and AlSnI₃, respectively. The confirmation of the semiconducting characteristics was achieved through the depiction of the density of states and the accurate assessment of atomic orbitals. All the perovskites have exceptional optical features in the visible spectrum, including excellent dielectric constant, refractive index, absorption capacities and conductivity. Additionally, AlSnF₃, AlSnCl₃, AlSnBr₃ and AlSnI₃ halides exhibit the largest absorption peak within the ultraviolet spectrum around 3.51 × 10⁵ cm^–1 at 22.7 eV, 3.51 × 10⁵ cm^–1 at 22.7 eV, 3.51 × 10⁵ cm^–1 at 22.7 eV, and 3.77 × 10⁵ cm^–1 at 19.3 eV, respectively. All of the investigated perovskites’ mechanical stability was confirmed using the bond stability standard. Moreover, its intrinsic stiffness, ductility, anisotropic characteristics and machinability are essential for enduring durability in fabrication processes. Thermodynamic evaluations confirmed the thermally stable nature of these perovskites throughout extensive ranges of temperature. This study’s findings revealed that AlSnX₃ (X = F, Cl, Br and I) perovskites could emerge as promising optical materials, and their synthesis in the upcoming days is highly anticipated.

In this study, hydrated tungsten oxide quantum dots (WO₃QDs) were synthesized using an electrochemical oxidation process, followed by thermal treatment via conventional and microwave heat treatment. The conventional and microwave treatments were carried out at 150°C for 45 and 8 min, respectively. The average heating rates of conventional and microwave heat treatment are 5.1 and 20.3°C min⁻¹, respectively. Heat treatment resulted in partial dehydration of hydrated WO₃QDs and generated oxygen vacancies in the lattice. Electrochemical response of as-synthesized, conventionally heat-treated, and microwave-treated WO₃QDs was measured using 1 M H₂SO₄ as electrolyte. In general, microwave-treated WO₃QDs showed better cyclic voltammetry characteristics as compared to conventionally heat-treated samples. Highest specific capacitance of 412.4 Fg⁻¹ was achieved for the microwave-treated sample at a scan rate of 10 mVs⁻¹. Correspondingly, high energy density (56.3 Whkg⁻¹) and high power density (3060 Wkg⁻¹) was noted for microwave-treated samples. The chronopotentiometry response of all samples dominantly exhibited diffusion-controlled behaviour with very small IR drop. These findings indicate that microwave-treated WO₃QDs are effective electrode materials and can be considered suitable for enhancing the performance of supercapacitors.

This research examines the effects of silane modifications on polyamide 12 (PA-12) to improve its mechanical and thermal properties. The study employs a reactive extrusion technique to integrate various silanes—Dynasylan^® AMEO, Dynasylan^® 1189, Dynasylan^® DAMO and Dynasylan^® VPS 4721—at different concentrations (0.25, 0.5 and 0.75%). Key findings reveal that silane modifications significantly enhance the tensile strength, impact resistance and viscoelastic behaviour of PA-12, with the Dynasylan^® DAMO formulation achieving the highest tensile strength of 38.25 MPa vis-à-vis 8.02 MPa for PA-12. The modifications also resulted in a reduction of crystallinity by over 35%, contributing to improved toughness and impact strength. Rheological assessments indicate that the flow properties of PA-12 are positively altered, enhancing its complex viscosity and storage modulus, which are crucial for applications in automotive and aerospace industries. Thermal analysis through differential scanning calorimetry and thermogravimetric analysis confirms improved thermal stability, particularly in the 0.5% Dynasylan^® AMEO-modified sample, exhibiting an onset temperature of 421.87°C. The study emphasizes the importance of the silane type and dosage in tailoring PA-12’s performance for advanced applications, suggesting future research directions to further refine silane-modification techniques for enhanced polymer performance. This research provides valuable insights into polymer-modification strategies, highlighting the potential for silane treatments to optimize the mechanical, thermal and rheological properties of PA-12 for diverse industrial applications.