Bulletin of Materials Science最新文献

This study investigates the effects of doping MgH₂ with rhodium (Rh) on hydrogen desorption activation energy, utilizing kinetic Monte Carlo simulations to elucidate the underlying mechanisms. The introduction of this transition metal significantly influences the desorption kinetics, with activation energies measured at 128.2 kJ mol^–1 for 6.25 wt% Rh and 136.3 kJ mol^–1 for 3.125 wt% Rh. The kinetic Monte Carlo simulations provide detailed isothermal Temperature Programmed Desorption profiles for each doped system, revealing that 6.25 wt% Rh doping notably reduces the activation energy and time required for hydrogen desorbed, thereby enhancing the desorption process. Rh doping presents intermediate effects, offering a nuanced understanding of how transition metal doping can be tailored to optimize hydrogen storage in MgH₂. These findings contribute valuable insights into the design of advanced hydrogen storage materials, making this study a significant addition to the field.

CuCr₂O₄ and Fe-substituted CuCr₂O₄ nanoparticles were synthesized via the sol–gel method, and their structural, morphological and optical/electrical properties were investigated using X-ray diffraction (XRD) and terahertz spectroscopy. XRD analysis revealed that the parent compound exhibits a tetragonal spinel phase, while Fe substitution induces a phase transition towards the cubic spinel structure. Dynamic light scattering measurements indicated a decrease in average particle size with increasing Fe content. Additionally, zeta potential measurements showed a reduction in surface charge upon Fe substitution, suggesting changes in colloidal stability or surface chemistry. Terahertz spectroscopy revealed that increasing Fe content led to a progressive increase in absorption coefficient, refractive index and dielectric constant across the series. As a result, the electrical conductivity of the nanoparticles increased with Fe substitution, likely due to enhanced charge carrier mobility or polaron hopping facilitated by the Fe dopants.

Two new hybrid compounds were synthesized by combining potassium N–(4-methylphenylsulfonyl)dithiocarbimate (DCBI) with layered zinc hydroxy salts: zinc hydroxynitrate (ZHN) and zinc hydroxyacetate (ZHA), using a coprecipitation method. The materials were characterized by X-ray diffraction (XRD), infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA), confirming the incorporation of the organic anion into the layered structure. DCBI and the host layers interact mainly through the CS₂ group. The compounds were evaluated as accelerators in the vulcanization of rubber and compared to the commercial accelerator ZEDC. The synthesized materials led to slower vulcanization reactions and vulcanizates with higher elongation at break and lower tear resistance. These features suggest that the materials may be suitable for applications that require greater flexibility and improved safety, presenting a promising alternative to conventional amine-based accelerators.

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The vulcanization process was conducted with the interlayer materials synthesized in this work.

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.

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