Beryllium-tungsten (Be-W) intermetallic compounds are promising candidates for fusion-reactor plasma-facing components and aerospace high-temperature structural materials owing to their low density, high elastic modulus, high melting point and excellent irradiation-corrosion resistance. Nevertheless, experimental acquisition of intrinsic physical properties for single-phase Be-W intermetallics remains challenging because of significant differences in the melting points of constituent elements and the tendency for elemental segregation during preparation. In this paper, first-principles calculations based on density functional theory with the GGA-PBE functional were performed to investigate the crystal structure, thermodynamic stability, electronic bonding and mechanical properties of Be2W, Be12W, and Be22W. The results reveal that Be12W has the lowest formation enthalpy and exhibits the strongest phase-forming ability, while Be2W shows relatively poor thermodynamic stability. All three phases are metallic with no band gap, and their bonding exhibits strong Be-p–W-d orbital hybridization with partial covalent features on the basis of metallic bonding. According to the Born–Huang stability criteria, Be2W, Be12W and Be22W are all mechanically stable. Be2W possesses superior resistance to volumetric deformation; Be12W achieves the highest shear modulus, Young’s modulus and theoretical Vickers hardness, but displays relatively high brittleness; Be22W has low elastic modulus and hardness within the range of 2–8 GPa, indicating favourable machinability yet insufficient structural stability. Comprehensive analysis demonstrates that Be12W is the optimal target phase for high-temperature irradiation-resistant Be-W-based structural materials. This work clarifies the structure–property relationships of Be-W intermetallics and provides theoretical support for composition optimization, phase regulation and experimental development of relevant advanced materials.
The electronic-structure traits of titanium (Ti), chromium (Cr), manganese (Mn), and nickel (Ni) doped-zinc sulfide (ZnS) through H2O molecule adsorption were investigated using first-principles studies. A detailed study was performed using density functional theory (DFT) calculations at the CAM-B3LYP-D3/6-311+G (d,p) level to investigate how H2O is captured by a ZnS, ZnSTi, ZnSCr, ZnSMn, or ZnSNi nanostructure. The shape of binding of hydrogen or hydroxyl groups to the surface of a ZnS, ZnSTi, ZnSCr, ZnSMn, or ZnSNi nanostructure could produce a weak signal close to the edge of the surface. This thought was accompanied by delving into the density of states, consisting of total, partial, and orbital-projected density of states, as well as electrostatic potential, for both the bare and water-covered surfaces of ZnS, ZnSTi, ZnSCr, ZnSMn, and ZnSNi. From this, it can be considered that Zn, Ti, Cr, Mn, and Ni in these complexes have a better capability to take in electrons when water is captured. These outcomes propose that the electronic properties of these complexes can be altered by controlling where water is absorbed on their surfaces. The target of this investigation is to detect routes to treat water and ameliorate the performance of titanium zinc sulfide, chromium zinc sulfide, manganese zin sulfide, and nickel zinc sulfide alloys as photocatalysts for wiping contaminants.
Nowadays, carbonized natural fiber composites are sustainable alternatives for electromagnetic wave absorption in unmanned aerial vehicles (UAVs). However, achieving a balance between electromagnetic performance, structural thickness, and weight is still difficult. This study, therefore, presents a multi-objective optimization framework for designing a lightweight radar-absorbing multilayer composite using a carbonized false banana fiber/Fe3O4 hybrid absorber. In this work, a four-layer sandwich panel was modeled in SOLIDWORKS 2017 and analyzed using full-wave electromagnetic simulation in ANSYS HFSS (R18.1) over the frequency range of 2–18 GHz. Layer thicknesses were optimized using a multi-objective particle swarm optimization (MOPSO) algorithm with three objectives: maximizing the frequency-averaged power absorptivity, minimizing panel mass, and minimizing total thickness. The objectives were handled simultaneously through Pareto dominance without predefined weighting coefficients, and a compromise solution was selected from the resulting Pareto-optimal set. The selected Pareto compromise was subsequently adjusted considering practical layer-thickness and manufacturability requirements, resulting in a 2/5/2/1 mm multilayer configuration with a total thickness of 10 mm. The resulting configuration achieved frequency-averaged power absorptivities of 0.6756 over 2–18 GHz and 0.8289 within the Ku-band, together with an effective absorption bandwidth of 3.2 GHz for power absorptivity above 90%. A minimum reflection coefficient magnitude of 0.0230 (corresponding to a peak power absorptivity of 99.95% at resonance) was obtained, with a minimum reflection loss of −32.75 dB. The optimized panel achieved a mass of 0.1725 kg, corresponding to a modest 1.42% reduction relative to an equal-footprint, equal-thickness monolithic carbon-fiber reference panel. These numerical results show the potential of combining a biomass-derived absorber with multi-objective optimization for the preliminary design of UAV-oriented radar-absorbing multilayer structures.
The Dion–Jacobson perovskite solid acid, HLaNb2O7, is an important intermediate in many topochemical reactions such as those involving ion exchange, intercalation, exfoliation, and grafting. Rietveld structure refinement of time-of-flight neutron diffraction data (7.66 K, P4/mmm, a = b = 3.8907(3) Å, c = 10.5068(9) Å) shows that protons bridging across the HLaNb2O7 interlayer serve to align LaNb2O7 blocks through NbO6 apical oxygens. The oxygens are 2.54 Å apart, with the intermediate proton distributed over two half-occupied sites, and 1.15(10) Å from the closest oxygen. Such short strong hydrogen bonds are shorter (1.40 Å) than are typical for many known mixed metal oxide solid acids (ca. 2.8 Å–3.5 Å). Anisotropic refinement of the hydrogen thermal parameter reveals an elongation suggesting an active hydrogen that moves between the two oxygens, O–H…O ↔ O…H–O; DFT modeling supports this behavior, finding a minimal activation energy between two states; and infrared studies (FTIR) exhibit a broad low-energy band at ~1600 cm−1, associated with the hydrogen resonance between the apical oxygens. These results are discussed in terms of structure, strong low-barrier hydrogen bonding, and proton mobility.
β-Type titanium alloys mitigate stress shielding through their low elastic modulus, but their limited wear resistance restricts their use in articulating surfaces. This study evaluated the effect of a 100 nm Au interlayer on the structural, electrochemical, tribocorrosion and biological behaviour of TaN coatings deposited by magnetron sputtering on aged Ti-13Nb-13Zr. Coatings were characterised by XRD, SEM and AFM and assessed by potentiodynamic polarisation, electrochemical impedance spectroscopy and ASTM G119 tribocorrosion tests in Ringer’s lactate at 37 °C, ICP-MS, and MTT and LDH assays with MG-63 cells. Both coatings were columnar and dominated by δ-TaN; the interlayer attenuated the ε-TaN and γ-Ta2N phases and increased the crystallite size from 24 ± 3 to 31 ± 2 nm. The TaN/Au system shifted the corrosion potential from −210 ± 18 to +35 ± 10 mV vs. Ag/AgCl and lowered the corrosion current density 23-fold. Under tribocorrosion, the friction coefficient fell from 0.28 to 0.17, the wear volume fell 7.2-fold and the synergistic fraction fell from 35% to 14%. Ti release fell from 1.85 to 0.16 µg·cm−2 and 72 h cell viability rose from 82 ± 5% to 96 ± 3%. A nanometric noble interlayer is therefore a promising strategy for articulating surfaces of β-titanium alloys.
