Solids

This review systematizes data on the phase composition and key properties of compounds in the W–B system, including thermodynamic stability, crystal structure, and hardness. The current understanding of the binary W–B phase diagram and the stability of individual borides is discussed, alongside the influence of defects and non-stoichiometry on their properties. The main methods for synthesizing these materials and producing coatings based on them are summarized. Potential applications of tungsten borides are highlighted, particularly for high-temperature environments, cutting tools, and protective and functional coatings. Finally, key directions for future research are outlined, focusing on the refinement of phase equilibria, the scaling of production methods, and the development of W–B-based materials with tailored performance characteristics. Full article

Enhancing the solubility and processability of graphene remains a critical challenge, limiting its integration into advanced materials systems. In this work, poly(tert-butyl acrylate) (PtBA) and poly(N-isopropyl acrylamide) (PNIPAM) were grafted onto graphene via controlled atom transfer radical polymerization (ATRP) to create well-defined polymer–graphene hybrids with tunable interfacial properties. ATRP enabled the synthesis of PtBA and PNIPAM homopolymers with narrow molecular weight distributions and systematically varied chain lengths (4–18 kDa), allowing direct correlation between polymer architecture and material performance. Notably, the thermos-responsive behavior of PNIPAM was strongly dependent on chain length, highlighting the importance of controlled polymer design. Raman and FTIR spectroscopy confirmed successful grafting and chemical modification of the graphene surface. In addition, pilot studies demonstrate the ATRP synthesis of PtBA-b-PNIPAM block copolymers and their hydrolysis to PAA-b-PNIPAM, providing a platform for future development of multifunctional graphene interfaces. Overall, this study establishes a versatile and precisely controlled route for engineering polymer-grafted graphene with enhanced solubility and tunable functionality, enabling broader applications in smart materials and hybrid nanocomposites. Full article

Aluminum foam is expected to be applied in various industrial fields as a lightweight, multifunctional material. When it is used as an industrial product, it is essential to form it into the required shape. There have been some attempts to form aluminum foam. However, the formability remains low. In this study, we attempted to form aluminum foam, which was fabricated by heat foaming a precursor, into a flat plate by reheating it above its foaming temperature and then roller forming it. It was found that heating above the foaming temperature and subsequent roller forming enabled the aluminum foam to be formed into a flat plate without causing defects. In a sample in which the precursor was roller-formed immediately after foaming, it was found that compared to the as-foamed aluminum foam, the decrease in porosity was limited to approximately 5%, enabling roller forming while minimizing the influences on pore structures. In samples that were roller-formed after reheating, porosities slightly decreased, but most pores were retained. Even when the aluminum foam was roller-formed to the same thickness as the initial precursor before foaming, the porosities exhibited around 65%, limiting the reduction in porosities to approximately 15% compared to the as-foamed aluminum foam. Full article

Tin oxide thin films were deposited by the pulsed laser ablation of a metallic Sn target at different oxygen partial pressures, ranging from 10 to 40 mTorr. Langmuir plasma probe diagnostics were performed to evaluate the effect of pressure on mean kinetic energy and density of Sn ions. It was observed that the mean kinetic energy decreased from 34 to 11 eV while the ion density decreased from 10 to 1.5 × 10¹³ cm⁻³ with increasing pressure. The films exhibited enhanced optical transmittance, increasing from 10% for the sample grown at 10 mTorr to 70% for the film deposited at 40 mTorr. Furthermore, higher deposition pressures led to wider band gap values, increasing from 1.6 to 3.9 eV for direct transitions and from 2.2 to 3.2 eV for indirect transitions with increasing oxygen pressure. These trends are consistent with progressive oxidation and partial transparency characteristic of semiconducting tin oxides. Structural characterization, based on X-ray diffraction, revealed predominantly metallic Sn diffraction peaks across the entire oxygen pressure range. However, despite this structural signature, the films exhibited optical and electronic properties characteristic of tin oxides. This apparent discrepancy suggests the coexistence of metallic nanoparticles embedded within an amorphous or nanocrystalline SnO₂/SnO_x matrix. These findings provide insights into the non-equilibrium oxidation dynamics of tin and the formation of metastable SnO_x phases during pulsed laser deposition. Full article

Adhesive bonding has emerged as a promising technology for joining carbon fiber reinforced polymer (CFRP) structures in aircraft, offering advantages over traditional mechanical fastening such as weight reduction and uniform stress distribution. This study evaluates the effectiveness of innovative laser ablation and electrospinning surface treatments compared to the conventional peel-ply method for secondary bonding. Surface features and wetting behavior were characterized using scanning electron microscopy (SEM) and contact angle measurements, while mechanical performance was assessed via single lap shear tests. Results demonstrate that laser ablation (30 W power, 10 m/s speed) achieved the highest bond strength at 20.68 MPa, followed by electrospinning (18.20 MPa) using 10 wt% PA-66 nanofibers. Both advanced techniques significantly outperformed the peel-ply method, which yielded the lowest shear strength of 15.18 MPa. SEM analysis confirmed that laser treatment facilitated direct fiber exposure with minimal damage, while nanofibers provided enhanced physical interlocking. In conclusion, laser ablation proved to be the most effective technique for enhancing interfacial bonding in aerospace-grade CFRP structures, followed by electrospinning, offering a superior alternative to traditional surface preparation. Full article

The VDA 238-100 tight radius bend test has gained widespread acceptance for plane strain fracture characterization of sheet metals in proportional loading without necking. The VDA test features a 60 × 60 mm² square blank with a 0.2 mm or 0.4 mm radius punch to provide plane strain bending where the fracture limit of the material is lowest. However, the through-thickness gradients that suppress necking and promote fracture on the convex surface in tension can be exploited to efficiently characterize the fracture strain from uniaxial to plane strain tension by varying the sample width. In this study, V-bend tests were conducted for various sample widths for four advanced high-strength steels: 980GEN3, DP1180, MP800-V1, and MP800-V2 with the local fracture strains measured using digital image correlation. Reducing the width-to-thickness ratio below five altered the stress state at the failure location, with an aspect ratio of one providing edge fractures under uniaxial tension. This aspect ratio was then applied to 980GEN3 and MP800 steel samples with punched edges as it provides an efficient method for sheared edge fracture characterization that is not susceptible to necking as with common sheared edge tensile tests. To mitigate strain averaging inherent in DIC near surfaces, a geometric-based arc length methodology was proposed. The sheared edge fracture limits from the V-bend tests were then compared with the results from conical hole expansion and in-plane bend tests. The sheared edge formability was observed to have a material-dependent sensitivity to the test method. MP800-V2, with centerline segregation, exhibited a pronounced sensitivity to the applied deformation mode with absolute differences in fracture strains of 0.13 while the MP800-V1 and 980GEN3 did not. Full article

This study developed a sonoseeding strategy for controlling the crystal size of acetaminophen during cooling crystallization by introducing sonication into a supersaturated solution, thereby inducing nucleation. Based on the synthetic route of acetaminophen, crystallization behavior in both water and acetic acid aqueous solutions was investigated, along with the influence of a structurally related additive, p-aminophenol, on nucleation. To establish the sonoseeding approach, the solubility of acetaminophen in water and an aqueous solution of acetic acid, with and without the additive, was measured over a temperature range of 10–70 °C using a titration method. In parallel, the nucleation temperatures and metastable zone widths of acetaminophen were systematically determined during cooling crystallization under varying operating conditions. Results demonstrate that sonication effectively induces nucleation and significantly narrows the metastable zone width, particularly in aqueous solutions of acetic acid. Guided by the determined solubility and nucleation behavior, sonoseeding crystallization experiments were conducted at various supersaturation levels, allowing for the efficient control of acetaminophen crystal size, which ranged from 27 μm to 95 μm, with narrower particle size distributions compared to spontaneous nucleation. Furthermore, the recrystallized acetaminophen was confirmed as Form I using PXRD, DSC, and FTIR analysis. This study demonstrates that the sonoseeding approach is an efficient method for controlling crystal size during the crystallization of active pharmaceutical ingredients. Full article

Ceramic Matrix Composites (CMCs) have emerged as a structural material alternative to nickel superalloys for high-pressure turbines (HPT) components operating at high temperature, like shrouds. Despite the outstanding thermal stability of the CMCs, limited cooling is still necessary due to the extreme thermal operating conditions necessary to maximize engine performance and minimize fuel consumption. The design of CMC components, indeed, must consider a maximum service temperature that should not be exceeded to avoid damage and accelerated oxidation. The cooling, on the other hand, may induce the formation of thermal gradients and thermal stresses. In this work, different design options for the cooling system are investigated to minimize the thermal stresses of an HPT shroud-like geometry subjected to maximum temperature constraints on the material. Cooling is obtained via colder air jet streams (air taken from the compressor), whose impact position (the surface where the cold air impacts the component) has a different effect on the temperature field and on the induced stress field. Besides stress evaluation with different cooling systems, an ONERA damage model is investigated at a key location to potentially take into account stress components acting simultaneously and potential stiffness degradation of the CMC. Finally, the design evaluation of potential discrete crack propagation is discussed. A standard cohesive elements approach has been compared with a brittle element death approach. The results showed that the cohesive element approach resulted in shorter crack propagation, underestimating the actual crack behavior due to the embedded stiffness degradation method, while the element death returned encouraging results as a quicker, less complex, but still accurate design evaluation. Full article

Magnesium–sulfur (Mg-S) batteries represent a novel category of multivalent energy storage systems, characterised by enhanced theoretical energy density, material availability, and ecological compatibility. Notwithstanding these benefits, the practical implementation of this approach continues to be hindered by ongoing issues, such as polysulfide shuttle effects, slow Mg²⁺ transport, and significant interfacial instability. This study emphasises recent progress in utilising transition metal chalcogenides (TMCs) as cathode materials and modifiers to overcome these challenges. We assess the structural, electrical, and catalytic characteristics of TMCs such as MoS₂, CoSe₂, WS₂, and TiS₂, highlighting their contributions to improving redox kinetics, retaining polysulfides, and enabling reversible Mg²⁺ intercalation. The review synthesises results from experimental and theoretical studies to offer a thorough comprehension of structure–function interactions. Particular emphasis is placed on morphological engineering, modulation of electronic conductivity, and techniques for surface functionalisation. Furthermore, we examine insights from density functional theory (DFT) simulations that corroborate the observed enhancements in electrochemical performance and offer predictive direction for material optimisation. This paper delineates nascent opportunities in Artificial Intelligence (AI)-enhanced materials discovery and hybrid system design, proposing future trajectories to realise the potential of TMC-based Mg-S battery systems fully. Full article

During long-term storage, polymer-bonded explosives (PBXs) undergo thermal-oxidative aging due to environmental factors such as moisture and oxygen, which leads to a critical determinant of explosive performance. This study employed molecular dynamics simulations to investigate the impact of thermal-oxidative aging of butadiene rubber and paraffin wax composites used in the RDX-based polymer-bonded explosives. The interfacial binding energy between the binder system and RDX crystalline surfaces was evaluated. The cohesive energy density (CED), fractional free volume (FFV), mean square displacement (MSD), and mechanical properties were analysed to probe the mechanism of aging for butadiene rubber (BR) and paraffin wax (PW). The results demonstrate that, with progressive aging, the oxidation-induced chain scission of BR molecules leads to an increase in both the CED and solubility parameter of the BR/PW system. Initial oxidation reduces the FFV of the BR/PW system from 0.183 to 0.166, while subsequent chain scission causes the FFV to rise to 0.175. In terms of mechanical properties, the BR/PW system exhibits ductile behavior, with reductions in both Young’s modulus and shear modulus as aging progresses, leading to decreased material stiffness. For the RDX/binder system, oxidation enhances the interfacial binding energy, whereas chain scission in BR leads to a slight decline in the binding energy. Overall, oxidation exerts a more pronounced influence on the interfacial binding energy compared to chain scission. Full article

Atomic-scale strain is the basis of a material’s macroscopic deformation behavior. The current measure of atomic-scale strain in the form of the Green–Lagrange tensor loses its physical meaning beyond the yield point, as atomic neighborhoods undergo significant reconstructions. We have recently introduced a new atomic-scale strain measure, namely, atomic bond strain, through our study of bond behavior in multicomponent metallic glasses. Here, we apply this new strain measure to uniaxial tensile tests (simulated using molecular dynamics) of several representative single-crystal FCC (face-centered cubic) metals under varied strain rates. We show that this new strain measure displays remarkable near-linear correlation with stress, not only in the elastic regime, but also in the plastic regime where complex dislocation dynamics (nucleation, bursting, motion, annihilation, regeneration) and stress fluctuations take place. This suggests that the overall stress of the materials even in the plastic regime is predominantly determined by the degree of bond stretching among all atoms. This appears to contradict the common conceptions that the plastic flow stress of a crystalline material is governed by dislocation events involving only a small fraction of atoms around dislocations, and that the stress–strain relationship is highly non-linear for plastic deformation. The contradictions can be reconciled by considering the causal sequence: dislocation events alter bond stretching, and bond stretching directly determines the stress. This brings a novel insight into the nature of plastic deformation, owing to the newly introduced atomic bond strain. How well the near-linear correlation between the stress and the atomic bond strain holds in other materials (e.g., non-FCC single crystals, polycrystals, quasicrystals, elements, alloys, and compounds) is an intriguing and important topic for future investigation, following the example of this work. Full article

A spiral spin arrangement with a magnetic unit cell 28 times the size of the nuclear one has been reported for Fe spins below T_N = 80 K in bilayered van der Waals gapped FeOCl. In this work, we employ neutron magnetic diffraction and ac magnetic susceptibility to reveal a much smaller magnetic unit cell only 4 times the size of the nuclear one for Fe spins below T_N = 119 K, upon intercalation of 27% non-magnetic Na ions into the van der Waals gaps of FeOCl. X-ray emission spectra and X-ray absorption edge spectra reveal a charge transfer from the intercalated Na ions to the Fe sites, which partially reduces the Fe³⁺ into Fe²⁺ ions. The reduction results in a significantly increased Fe-O-Fe bond angle, which strongly enhances the antiferromagnetic superexchange (AFMSE) coupling relative to the competing ferromagnetic direct exchange (FMDE) coupling between neighboring Fe ions, thereby driving to a higher degree of magnetic symmetry and a substantially higher Neel temperature for the Fe spins in Na_0.27FeOCl. Full article

Understanding the corrosion mechanism inside waste incinerators is very important in order to prevent possible damage due to high operational temperatures in chemical reactions for burning raw hazardous materials. Moreover, it is critical to understand the corrosion mechanisms to identify whether the oxides formed are protective or not, enabling us to prevent mass change on the steel walls of heat exchangers in waste incinerators. Thus, the present work comprises a high-temperature corrosion study on four Ferritic alloys with different contents of Al, Si, and Mo which are capable of replacing expensive materials such as stainless steel. The corrosion behavior was evaluated in atmospheres with H₂O_(g), HCl_(g), and an additional mixture of both atmospheres at 500 and 600 °C over 300 h. A thicker but porous heterogeneous oxide scale was formed in the HCl atmosphere, mainly composed of Fe₂O₃ and Cr₂O₃. Under the water vapor atmosphere, the presence of (Fe0.6Cr0.4)₂O₃ was observed. Meanwhile, in the mixed atmosphere, the presence of FeCr₂O₄, Cr₂SiO₄, and (CrFe)₂O₃ was observed. The biggest mass loss was measured inside the water vapor atmosphere. In comparison, inside the mixed atmosphere, the oxide scale was thinner. Finally, it was concluded that the alloy with the best corrosion resistance in HCl and H₂O atmospheres was Fe9Cr1.5AlSi3Mo steel. Full article

Intrinsic optical bi-stability in dense two-level systems is developed for the bad cavity limit where electromagnetic modes are adiabatically eliminated. Each atom interacts via dipole–dipole forces with its nearby spatial distribution of atoms. The theory is developed into two parts, corresponding to the short sample, with dimensions shorter than the wavelength, and the long sample. In both cases, the local field corrections modify the Maxwell–Bloch equations, so that cubic or quartic equations are obtained for the inversion of population as a function of the external light intensity, thus leading to intrinsic bi-stability. The effects of noise sources on intrinsic bi-stability were treated, and I found that while the observability of bi-stability was not obtained experimentally for a simple two-level system, there were many observations of bi-stability obtained through the ‘up-conversion’ of rare earth excited crystals. I show the differences between these two systems. Full article

Sodium-ion batteries (SIBs) present a sustainable alternative to lithium-ion systems due to the abundance and low environmental impact of sodium. However, their integration into multifunctional structural battery systems that combine electrochemical and mechanical properties remains unexplored. This work investigates the electrochemical performance of sodium-ion chemistry within a structural battery framework using unsized carbon fiber (UCF) as both a structural substrate and active electrode material. Ultrasonic spray coating was employed to deposit Mesocarbon Microbeads (MCMB) and NaNi_1/3Fe_1/3Mn_1/3O₂ (NFM) on UCF to form hybrid anode and cathode half-cells, respectively, with 1 M NaPF₆ in diglyme electrolyte. The MCMB on UCF hybrid anode demonstrated dual graphitic and carbon fiber storage mechanisms, achieving 50 mAh g⁻¹ capacity over 500 cycles at 1C with excellent Coulombic efficiency. The NFM–UCF cathode exhibited an initial capacity of 27.5 mAh g⁻¹ and maintained over 80% capacity retention for 230 cycles, continuing to cycle stably beyond 400 cycles. Post-cycling SEM imaging revealed surface cracking, particle expansion, and gas-pocket formation in both electrodes. These results demonstrate the electrochemical viability of sodium-ion chemistry in a multifunctional structural configuration and establish ultrasonic coating as a scalable, precise method for fabricating carbon fiber electrodes toward future sodium-ion structural batteries. Full article

Thin-film organic solar cells (TFOSCs) are gaining momentum as next-generation photovoltaic technologies due to their lightweight nature, mechanical flexibility, and low cost-effective fabrication. In this pioneering study, we report for the first time the incorporation of cobalt-doped zinc sulfide $(\mathrm{Z}\mathrm{n}\mathrm{S}/\mathrm{C}\mathrm{o})$ nanoparticles (NPs) into a poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) bulk-heterojunction photoactive layer. $\mathrm{Z}\mathrm{n}\mathrm{S}/\mathrm{C}\mathrm{o}$ NPs were successfully synthesized via a wet chemical method and integrated at varying concentrations (1%wt, 3%wt, and 5%wt) to systematically investigate their influence on device performance. The optimal doping concentration of 3%wt yielded a remarkable power conversion efficiency (PCE) of 4.76%, representing a 102% enhancement over the pristine reference device (2.35%) under ambient laboratory conditions. The observed positive trend is attributed to the localized surface plasmon resonance (LSPR) effect and near-field optical enhancement induced by the presence of ZnS/Co NPs in the active layer, thereby increasing light-harvesting capability and exciton dissociation. Comprehensive morphological and optical characterizations using high-resolution scanning electron microscopy (HRSEM), high-resolution transmission electron microscopy (HRTEM), and spectroscopic techniques confirmed uniform nanoparticle dispersion, nanoscale crystallinity, and effective light absorption. These findings highlight the functional role of $\mathrm{Z}\mathrm{n}\mathrm{S}/\mathrm{C}\mathrm{o}$ NPs as dopants in enhancing TFOSC performance, providing valuable insights into optimizing nanoparticle concentration. This work offers a scalable and impactful strategy for advancing high-efficiency, flexible, and wearable organic photovoltaic devices. Full article

Photoluminescence studies of single-crystalline SnO₂ grown by chemical vapor transport from SnCl₄ and H₂O vapors were carried out in the visible spectral range. A non-trivial dependence of the 2.6 eV emission band on temperature and optical excitation level was observed. Based on the obtained data, the ionization energy of a shallow donor in SnO₂ was estimated to be 7 meV. Additionally, a model of energy levels and radiative transitions associated with shallow donors and intrinsic defects is proposed. Full article

This study investigates the microwave absorption properties of the cuprate ceramic material Bi_1.7Pb_0.3Sr₂Ca₂Cu₃O₁₀ (BSCCO) and its composites with bismuth oxide (Bi₂O₃) in the 4–25 GHz frequency range. Composites with varying BSCCO contents were fabricated and characterized using the Nicolson–Ross–Weir method and Agilent Materials Measurement Software 85071E to determine complex permeability and permittivity. The 4 wt.% BSCCO composite exhibited a peak reflection loss of −32.6 dB at 12.5 GHz, while the 40 wt.% BSCCO composite reached a 52% microwave absorption ratio at 23 GHz. These results demonstrate that microwave absorption is strongly influenced by dielectric properties and the ratio of BSCCO and Bi₂O₃ composites. This work highlights the potential of BSCCO-Bi₂O₃ ceramics for microwave absorption applications, particularly in environments experiencing significant temperature gradients due to their thermal stability and electromagnetic performance. Full article

Mn⁴⁺-doped fluoride red phosphors are widely used in white LED lighting and display applications due to their excellent luminescent properties. However, their synthesis relies heavily on highly toxic aqueous hydrofluoric acid, which not only causes severe environmental and soil/water pollution but also makes it difficult to control the microstructure of the products due to the rapid reaction rate. In this study, low-melting-point NH₄HF₂ was used as the molten salt, with KMnO₄ and MnF₂ as manganese sources, to synthesize the red phosphor K₃AlF₆: Mn⁴⁺ via the molten salt method. After the reaction, impurities such as NH₄HF₂ were removed by washing with a dilute H₂O₂ solution. The microstructure, photoluminescence properties, thermal quenching behavior, and application in warm white light-emitting diodes (W-LEDs) of the K₃AlF₆: Mn⁴⁺ phosphors were investigated. The results indicate that the phosphors prepared by this method consist of a single pure phase. By adjusting the molten salt content, the morphology of the product can be transformed from nanoparticle-like to nanorod-like structures. All products exhibit the characteristic red emission of Mn⁴⁺ under blue and violet light excitation, with the optimally doped sample achieving an internal quantum efficiency (IQE) of 69% under blue light excitation. The combination of the obtained K₃AlF₆: Mn⁴⁺ with the yellow phosphor YAG enabled the fabrication of W-LEDs. These W-LEDs achieved a color rendering index (Ra) of 86.8, a luminous efficacy (LE) of 77 lm/W, and a correlated color temperature (CCT) of 3690 K, along with excellent color stability under operating conditions. Full article