Journal of Materials Research最新文献

Biomedical material advancements have resulted in an increasing demand for innovative and high-performance Akermanite (AKT-Ca₂MgSi₂O₇) ceramics developed for a diverse range of uses. This study conducts a comparative analysis and development of porous AKT structures, employing three distinct synthesis methods: ball milling, sol–gel, and a combining both processes. The objective is to evaluate the microstructural properties, porosity levels, mechanical strength, and bioactivity of the AKT. XRD study confirms the phase purity at 1300 °C, and FT-IR identified the respective functional groups present in the material composition. SEM analysis revealed the porous structure (~ 3–6 μm) of AKT samples, which had a uniform distribution. The results suggest that the combination process enhances the structural and functional properties of Akermanite. Biomineralization study reveals that hydroxyapatite formation was attained after 21 days. The achieved compressive strength is 193 ± 5 MPa. The outcome of the antibacterial activity against S. aureus and E. coli test strains suggests that viable material for orthopedic applications.

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To investigate naphthalene as a suspending fluid for freeze-casting applications, sterically stabilized suspensions of copper microparticles suspended in liquid naphthalene are directionally solidified in a Bridgman furnace. Colonies of nearly particle-free naphthalene lamellae, interspersed with particle-enriched interlamellar regions, are predominantly aligned in the direction of the imposed thermal gradient. As furnace translation velocities decrease from 80 to 6.5 μm s⁻¹, the thickness of naphthalene lamellae increases. For the lowest velocity, a transition to a lensing microstructure (with naphthalene bands aligned perpendicular to the solidification direction) is observed in central regions of samples. For all velocities, the naphthalene lamellae show (i) secondary dendritic arms on one of their sides and (ii) are thinnest within core regions relative to peripheral regions (closest to the crucible walls). Together, these observations suggest the presence of buoyancy-driven convection during solidification.

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BaTiS₃, a quasi-1D complex chalcogenide, has gathered considerable scientific and technological interest due to its giant optical anisotropy and electronic phase transitions. However, the synthesis of high-quality BaTiS₃ crystals, particularly those featuring crystal sizes of millimeters or larger, remains a challenge. Here, we investigate the growth of BaTiS₃ crystals utilizing a molten salt flux of either potassium iodide, or a mixture of barium chloride and barium iodide. The crystals obtained through this method exhibit a substantial increase in volume compared to those synthesized via the chemical vapor transport method, while preserving their intrinsic optical and electronic properties. Our flux growth method provides a promising route toward the production of high-quality, large-scale single crystals of BaTiS₃, which will greatly facilitate advanced characterizations of BaTiS₃ and its practical applications that require large crystal dimensions. Additionally, our approach offers an alternative synthetic route for other emerging complex chalcogenides.

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This research article focused on 3D-printed multilayered polymer composite materials, with a particular emphasis on ceramic and carbon polymer composite materials. To evaluate the mechanical performance of a multilayered composite structure, ceramic polymer composite (CPC) materials were used layer by layer with carbon-reinforced polymer composite (CRPC) layers. Tensile, compression, flexural, and differential scanning calorimetry tests were carried out on 3D-printed CPC, CRPC, and Functionally Graded Multilayered Material (FGMLM) composite structures. The results indicated that FGMLM laminates exhibited increases of 12.4%, 6.4%, and 9.8% in tensile, flexural, and compressive strength, respectively, compared with CRPC laminates; these experimental values were validated by finite element analysis. Further, fractography analysis of the FGMLM was carried out using scanning electron microscopy to provide insights into the structural characteristics. It was indicated that strong interfacial bonding was found between the laminated carbon and ceramic layers.

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Electromagnetic interference (EMI) shielding has been a fundamental challenge because of the low wave impedances with monolithic metallic shields at low frequencies. Multilayered structures are considered an alternative to traditional monolithic shielding materials. This paper investigates such multilayered conductors of cobalt–nickel–iron alloy (CoNiFe) and copper (Cu) to illustrate their superiority over conventional monolithic shields. Modeling, simulations, and measurements demonstrate improved shielding when multilayered stacks are used against magnetic field sources. Furthermore, the stack-ups have excellent shielding even with a thickness of 5 µm. At least 40 dB of additional shielding effectiveness is achieved across 30–1000 MHz as compared to single-layer shielding from monolithic Cu of the same thickness. These innovative stack-ups also exhibit superior shielding when compared to multilayered stacks and shielding materials in literature. Additionally, these stack-ups are fabricated using standard substrate processes such as electroplating. Consequently, this approach becomes commercially viable and applicable to future electronic systems.

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Understanding the crystallographic texture is of paramount importance for the suppression of segmentation in chips with refined microstructure in Ti–6Al–4V alloy. Segmentation is pronounced at all cutting speeds thereby hindering grain refinement in chips. This study illustrates that the crystallographic texture, not ductility, controls the segmentation in chips. The initial workpiece texture is modified by cold-rolling to 30% and 40% thickness reduction prior to cutting. The microstructure of chips revealed a gradual transformation of morphology from segmented to continuous. The suppression of chip segmentation stems from the texture of the workpiece. Texture studies of workpieces have revealed that the sheets exhibited a strong transverse texture which gradually becomes weak during cold-rolling. The weak transverse texture rather than ductility, obtained from the tensile experiments, is responsible for the continuous shear in chips.

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β-W is a potential candidate for spintronic devices, but its formation is a challenge as it is metastable and is stabilized by O doping. Here, using ab initio calculations, we study N doping in W and find it to favor octahedral interstitial sites in α-W but tetrahedral interstitial sites in β-W. The solution energy of N in both α- and β-W is endothermic that makes a transition from α to β-W difficult. However, calculations on interaction of N and N₂ on small clusters of W for reactive deposition of W films show that N₂ dissociates on W clusters leading to the incorporation of N in the W film. Further ab initio molecular dynamics simulations on N and O co-doping in α- and β-W show that the β phase becomes energetically favorable over α-W making it possible to form β-W with low O doping and its applications in devices.

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Machine learning (ML) is progressively supplanting conventional trial-and-error approaches for designing alloys with desirable properties. In this study, four ML regression models were utilized to identify high-entropy alloys (HEAs) with high hardness within the Fe–Co–Ni–Cr system. The Bayesian optimized deep learning (BO-DL) method yielded the highest prediction accuracy (R² = 0.93). Notably, the BO-DL method is no longer limited to a single HEA system and now can target different alloy systems composed of more elements with reliable prediction results. Furthermore, a genetic algorithm was utilized to search for HEAs with high hardness. The accuracy and reliability of the predictions were experimentally verified. As-cast Fe₅Co₂₀Ni₁₀Cr₃₀Al₅Ti₃₀ HEA exhibited a remarkable hardness of 890 HV, which is one of the highest for alloys in the Fe–Co–Ni–Cr system. The methodologies and framework proposed in this study can serve as a blueprint for facilitating the design of HEAs.

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Diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide (TPO) fabricated into nanoparticle form with increased water dispersibility has enabled broader applications for the bioprinting of hydrogel scaffolds. In this study, the use of TPO NP as a photoinitiator for bioprinting gelatin methacrylate (GelMA) was compared with commonly used lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) photoinitiator by assessing the physico-chemical properties, mechanical strength, gelation kinetics, resistance to flow, absorptivity in different solvents, and biological responses. The results demonstrated that the physico-chemical and mechanical properties of the GelMA were similar using LAP and TPO nanoparticles (NP) for crosslinking. The significant cytotoxicity observed in cells exposed to the GelMA with TPO NP suggests that cell-embedded bioprinting may not be feasible and that removal of toxicant may be needed to utilize GelMA scaffolds crosslinked with TPO NP for biological applications. The results of this study provide a framework for future studies that will consider the microstructure and in vitro properties of GelMA.

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To further apply MoS₂ as a promising non-noble catalyst for addressing environmental issues, its catalytic ability must be improved. As a result of the hetero-atom doping effect and varied structure phase of MoS₂, we demonstrated excellent piezocatalysis for the degradation of methylene blue (MB) dye under stirring/ultrasonic catalyzed by MoS₂. Compared with pristine MoS₂ and O-doping MoS₂ (O-MoS₂), O-MoS₂& reduced graphene oxide (O-MoS₂&rGO) exhibits enhanced piezocatalytic activity. When the initial concentration of MB solution is ≤ 15 mg L⁻¹, both stirring and ultrasonication can make the optimal O-MoS₂&rGO composite to degrade the dye completely within 20 min. The experimental results have led to the proposal of a mechanism that elucidates the enhancement effect of rGO and O doping on the piezocatalytic performance of MoS₂. This study highlights the significance of constructing heterostructure interfaces and the impact of hetero-atom doping on the promotion of piezocatalysis efficiency.

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Boosting the catalytic ability of MoS₂ is vital to its further application as a class of promising non-noble catalysts to address environmental issues. Benefiting from the O-doping-induced electronic effect and interfacial coupling and synergistic effect between MoS₂ and reduced graphene oxide (rGO), the as-prepared O-MoS₂&rGO heterogeneous catalyst exhibits enhanced degradation efficiency for methylene blue (MB) dye.