Structural Materials Research Articles

Strong and Fireproof Regenerated Wood via a Combined Phosphorylation-Surface Nanofibrillation and Ionic Cross-Linking Strategy.

To reduce the environmental impact of plastics, an increasing number of high-performance sustainable materials have emerged. Among them, wood-based high-performance structural materials have gained growing attention due to their outstanding mechanical and thermal properties. Here, we introduce phosphate groups onto the wood veneers for surface nanofibrillation, effectively altering both the molecular structure and surface morphology of wood, which enhances the interactions between wood veneers and endows the wood with excellent fire resistance properties. With these phosphorylated wood-based building blocks, "chemical welding" structural materials (CWSMs) obtained through chemical cross-linking exhibit excellent mechanical properties. The flexural strength of CWSM reaches 225 MPa, and the modulus reaches 16 GPa, surpassing those of various types of natural wood. At the same time, phosphorylation has endowed CWSM with excellent fire resistance, with a limiting oxygen index reaching 49%, making it completely noncombustible. More importantly, as a biomass-based structural material, CWSM exhibits mechanical, thermal, and fire resistance properties and degradability far superior to those of traditional petroleum-based plastics, making it an ideal candidate for plastic replacement.

Enhancing the CO Oxidation Performance of Copper by Alloying with Immiscible Tantalum.

Copper-tantalum (Cu-Ta) immiscible alloy nanoparticles (NPs) have been the subject of extensive research in the field of structural materials, due to their exceptional nanostructural stability and high-temperature creep properties. However, Cu is also a highly active oxidation catalyst due to its abundant valence changes. In this study, we have for the first time obtained homogeneous CuxTa1-x (x = 0.5, 0.7, 0.9, 1) nanoparticles by wet coreduction with an average particle size of approximately 30 nm. Testing verified all the CuxTa1-x/TiO2 (x = 0.5, 0.7, 0.9) showed higher CO oxidation activity than Cu/TiO2, with Cu0.7Ta0.3/TiO2 exhibiting the most promising performance. The temperature-programmed reduction with hydrogen demonstrated that Cu0.7Ta0.3/TiO2 exhibits enhanced redox properties. While kinetic studies indicated that the reaction of the Cu0.7Ta0.3/TiO2 catalyst followed the Langmuir-Hinshelwood mechanism, in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) verified the introduction of Ta induced the generation of bicarbonate as an intermediate product and increased the adsorption capacity of Cu+ on CO in the catalyst, which facilitated the reaction of surface adsorbed CO with oxygen and led to the enhanced CO oxidation activity.

A Robust, Biodegradable, and Fire-Retardant Cellulose Nanofibers-Based Structural Material Fabricated from Natural Sargassum.

With increasing concern about the environmental pollution of petrochemical plastics, people are constantly exploring environmentally friendly and sustainable alternative materials. Compared with petrochemical materials, cellulose has overwhelming superiority in terms of mechanical properties, thermal properties, cost, and biodegradability. However, the flammability of cellulose hinders its practical application to a certain extent, so improving the fire-retardant properties of cellulose nanofiber-based materials has become a research focus. Here, cellulose nanofiber and alginate are extracted from abundant natural sargassum as high-strength nanoscale building blocks, and then a sargassum cellulose fire-retardant structural material is prepared through a bottom-up hydrogel layer-by-layer method. The structural materials obtained incorporate excellent mechanical properties (≈297 MPa), thermal stability (≈200°C), low thermal expansion coefficient (≈7.17 × 10-6 K-1), and fire-retardant properties. This work largely improves the utilization of seaweed residue and natural polymers, providing a bio-based fire-retardant strategy, and has a wide range of development prospects in the field of fiber-based high-performance structural materials in the future.

The Microstructures, Mechanical Properties, and Energetic Characteristics of a Novel Dual-Phase Ti40Zr40W10Mo10 High-Entropy Alloy

High-energy structural materials (ESMs) integrate a high energy density with rapid energy release, offering promising applications in advanced technologies. In this study, a novel dual-phase Ti40Zr40W10Mo10 high-entropy alloy (HEA) was synthesized and evaluated as a potential ESM. The alloy exhibited a body-centered cubic (BCC) matrix with Mo-W-rich BCC precipitates of varying sizes, which increased proportionally with the W content. The compressive mechanical properties were assessed across a range of strain rates, revealing that the W10 HEA sustained a compressive strength of 2300 MPa at a strain rate of 3000 s−1. This exceptional performance is attributed to the uniform distribution of circular Mo-W-rich BCC precipitates. Conversely, in the W13 HEA, the aggregated and large Mo-W-rich precipitates deteriorated its dynamic properties. Furthermore, deflagration behavior was observed during dynamic deformation of W10, highlighting its potential as a high-performance ESM.

Impact of Tunnel Fire and High Ground Temperature on the Durability and Thermal Damage Mechanism of Structural Materials

The goal of this paper is to investigate how tunnel fires and high temperatures interact to reduce the structural and thermal properties of tunnelling materials, namely concrete and steel. The work looks at microstructural modifications in concrete (pore expansion, micro-cracking, and the chemical degradation of calcium silicate hydrate (C-S-H) that reduce compressive strength and make concrete porous). Oxidation, surface scaling and yield strength degradation under high temperature are studied in steels to evaluate their negative impact on the capacity to carry loads. The paper also incorporates simulated data on how the insulation material performs over time as a result of repeated high-temperature exposure. Such results emphasise the double-edged structural hazard of fire and geothermal heat, which hastens material decomposition, weakens robustness and undermines long-term stability of critical infrastructure. The paper ends with suggestions for new, thermophilic materials to make tunnels safer in extreme conditions

The Viability of the Refractory High‐Entropy Alloy AlMo0.5NbTa0.5TiZr for High‐Temperature Structural Applications

There is significant motivation to produce new structural materials for high‐temperature service, so that enhanced efficiencies can be realized for next‐generation power and propulsion applications. High‐entropy alloys incorporating refractory elements have been shown to be a viable source of potential new materials for these applications. Despite this, significant work is required in order to evaluate the suitability of these materials for operation in extreme environments of temperature and mechanical load. Herein, AlMo0.5NbTa0.5TiZr alloy is first reported on, for the first time providing an in situ determination of the B2 solvus, correlated to the changes in mechanical properties. In addition, a low‐temperature (800 °C) regime of catastrophic accelerated oxidation is identified, which is discussed in context of the potential future applications for this alloy. These results highlight significant limitations in AlMo0.5NbTa0.5TiZr and related alloys, which make them unsuitable for commercial application in their current form.

Highly Efficient and achromatic mid-infrared silicon nitride meta-lenses

Inverse design with topology optimization considers a promising methodology for discovering new optimized photonic structure that enables to break the limitations of the forward or the traditional design especially for the meta-structure. This work presents a high efficiency mid infra-red imaging photonics element along mid infra-red wavelengths band starts from 2 to 5 µm based on silicon nitride optimized material structures. The first two designs are broadband focusing and reflective meta-lens under very high numerical aperture condition (NA = 0.9). The two designs are modeled by inverse design with topology optimization problem with Kreisselmeier–Steinhauser (k–s) aggregation objective function, while the final design is depended on novel inverse design optimization problem with double aggregation objective function that can target bifocal points along the wavelength band producing high efficiency achromatic broadband multi-focal meta-lens under very high numerical apertures ().

Can Low Structural Anisotropy Produce High Optical Anisotropy? Anomalous Giant Optical Birefringent Effect in PI4AlI4 in Focus.

Tetrahedral halides with broad transparency and large second harmonic effects have the potential to serve as mid-infrared wide-bandgap materials with balanced nonlinear-optical (NLO) properties. However, their regular tetrahedral motifs tend to exhibit low optical birefringence (Δn < 0.03) due to limited structural anisotropy, which constrains their practical phase-matched capability. A significant challenge in halide structural chemistry and material exploration is to enhance the Δn of tetrahedral halides while maintaining their balanced properties. The question of whether tetrahedra with low structural anisotropy can produce high optical anisotropy remains unanswered. In this study, in addition to the conventional strategy of enhancing Δn by increasing structural anisotropy, we identify a previously unreported strategy of enhancing Δn by increasing electronic anisotropy. This novel strategy model unprecedentedly enhances the Δn of an existing tetrahedral halide, PI4AlI4, to a degree not achievable by conventional techniques, with the value reaching up to 0.31@1 μm. The anomalous increase in Δn is achieved by anisotropic charge redistribution resulting from a unique charge transfer effect between the anionic and cationic tetrahedral motifs. First-principles analysis provides further corroboration of the detailed chemical bonding electronic distributions and charge transfer illustrations. It is predicted that analogous AsI4AlI4 and TeI4ZnI4 will exhibit a greater propensity for giant Δn (> 0.5@1 μm). This finding will greatly enrich the structural chemistry of sp3-hybridized tetrahedra and provide seminal ideas for the design and modulation of highly birefringent structures.

Molten Salt Corrosion Studies of Sanicro‐25 by Electrochemical Techniques at High Temperature

ABSTRACTNickel and chromium‐based alloys are being considered structural materials for crucibles for electrorefining in pyrochemical reprocessing. LiCl–KCl molten salt is used as an electrolyte under an inert argon atmosphere. In the present work, the corrosion behavior of the Sanicro‐25 steel exposed to LiCl–KCl molten salt at 500°C with inert argon cover gas was explored using electrochemical methods like open circuit potential (OCP), linear polarization resistance, and electrochemical impedance spectroscopy (EIS). A change in the OCP of Sanicro‐25 towards the noble direction was observed. The linear polarization resistance, measured at various exposure intervals, decreased with the increase of molten salt exposure. The Nyquist plot consists of two semi‐circles with an incomplete semi‐circle at the lower frequency end, indicating the existence of three‐time constants and formation of intermittent oxide film. The oxide films formed over the surface are characterized by Raman analysis, X‐ray diffraction, X‐ray photoelectron spectroscopy, and scanning electron microscope coupled with elemental analysis. The formation of Fe3O4, Cr2O3, iron hydroxide, W‐oxides, and spinels are evidenced.

Improving the thermoelectric properties of septuple atomic-layer SnBi2Se4 by regulating the carrier concentration through Nb doping

Layered semiconductor materials have garnered significant attention in the thermoelectric field due to their excellent electrical property and intrinsically low lattice thermal conductivity. The septuple atomic-layered ternary compound SnBi2Se4 is reported as a promising thermoelectric material in both bulk and single-layer structures based on theoretical calculations, though experimental investigation remains unexplored. In this work, the melting and hot-press sintering methods were adopted to synthesize the septuple atomic-layered SnBi2Se4. Its unique layered crystal structure contributed to significant anisotropic transport properties and reduced thermal conductivity. However, its thermoelectric performance is constrained by a low carrier concentration that limits electrical conductivity. To solve this issue, the high-valent transition metal Nb was doped at Bi site to provide additional electrons. This doping resulted in a noticeable improvement in the performance of septuple atomic-layered SnBi2Se4 due to increased electrical conductivity and decreased thermal conductivity. Finally, a peak ZT ∼ 0.17 was obtained for SnBi1.97Nb0.03Se4 at 723 K, suggesting the effectiveness of Nb doping in enhancing the performance. These results indicate that septuple atomic-layered SnBi2Se4 is a highly promising thermoelectric material, though further performance improvements are needed.

Bio-Concrete and Its Self-Healing Capacity to Next-generation Sustainable Architecture: A Comprehensive Review

Concrete is commonly used as a foundation material in the construction sector. It's been around for over two centuries, and it looks like it'll keep being the material of choice for construction for the foreseeable future. Structural materials, long-term degradation creates microcracks which increases permeability and eventually lead to failure. Moreover, the identification and remediation of these fissures provide a formidable challenge, as they jeopardize the integrity and longevity of concrete buildings, particularly those subject to rigorous sealing criteria. Cement manufacturing and widespread usage both contribute to climate imbalance, with the former responsible for 5–7% of global carbon dioxide emissions. Biotechnology provides a viable alternative by allowing the culture of bacteria to produce calcium carbonate, a key ingredient in cement. Biomineralization and crystallization processes play a crucial role in the synthesis and transportation of concrete-compatible chemicals, enabling their delivery to fissure within concrete structures. This review paper discusses a methodology for advancing sustainable architecture in the future, utilizing the adaptable metabolic processes of microorganisms as a foundation. This involves integrating microbial technologies and materials created by microorganisms into the field of built environment design and construction. Currently, there is a growing presence in the market of innovative materials such as Bio-cement, which exhibit lower levels of embodied carbon compared to traditional materials. Furthermore, it discusses advancements in the synthesis and optimization of bio-concrete to address challenges in energy efficiency, structural integrity, and lifecycle performance. By bridging sustainability goals with cutting-edge technology, bio-concrete emerges as a cornerstone for resilient and eco-friendly infrastructure, laying the foundation for innovative architectural paradigms.

Dataset of tensile properties for sub-sized specimens of nuclear structural materials

Mechanical testing with sub-sized specimens plays an important role in the nuclear industry, facilitating tests in confined experimental spaces with lower irradiation levels and accelerating the qualification of new materials. The reduced size of specimens results in different material behavior at the microscale, mesoscale, and macroscale, in comparison to standard-sized specimens, which is referred to as the “specimen size effect.” Although analytical models have been proposed to correlate the properties of sub-sized specimens to standard-sized specimens, these models lack broad applicability across different materials and testing conditions. The objective of this study is to create the first large public dataset of tensile properties for sub-sized specimens used in nuclear structural materials. We performed an extensive literature review of relevant publications and extracted over 1,000 tensile testing records comprising 55 columns including material type and composition, manufacturing information, irradiation conditions, specimen dimensions, and tensile properties. The dataset can serve as a valuable resource to investigate the specimen size effect and develop computational methods to correlate the tensile properties of sub-sized specimens.

Electrocatalytic Mapping of Metal Fatigue with Persistent Slip Bands.

Metal fatigue, characterized by the accumulation of dislocation defects, is a prevalent failure mode in structural materials. Nondestructive early-stage detection of metal fatigue is extremely important to prevent disastrous events and protect human life. However, the lack of a precise quantitative method to visualize fatigue with spatiotemporal resolution poses a significant obstacle to timely detection. Here, we demonstrate a nondestructive electrocatalytic method to visualize metal fatigue, which is promising for future fatigue early detections. The persistent slip band (PSB) is considered one of the most consequential defect structures for metal fatigue failure. The selective electrochemistry is highly dependent on the metal crystallography and the collective dislocations in the PSB structure, enabling the amplification of the electrochemical response and differentiation of the fatigue stages at a submillimeter resolution. In addition, this nondestructive electrocatalytic method is applicable to several common metals, including copper, silver, iron, and aluminum, holding great significance where metal fatigue is a critical concern.

Computational microscopy with coherent diffractive imaging and ptychography.

Microscopy and crystallography are two essential experimental methodologies for advancing modern science. They complement one another, with microscopy typically relying on lenses to image thelocal structuresof samples, and crystallography using diffraction to determine the global atomic structure of crystals. Over the past two decades, computational microscopy, encompassing coherent diffractive imaging (CDI) and ptychography, has advanced rapidly, unifying microscopy and crystallography to overcome their limitations. Here, I review the innovative developments in CDI and ptychography, which achieve exceptional imaging capabilities across nine orders of magnitude in length scales, from resolving atomic structures in materials at sub-ångstrom resolution to quantitative phase imaging of centimetre-sized tissues, using the same principle and similar computational algorithms. These methods have been applied to determine the 3D atomic structures of crystal defects and amorphous materials, visualize oxygen vacancies in high-temperature superconductors and capture ultrafast dynamics. They have also been used for nanoscale imaging of magnetic, quantum and energy materials, nanomaterials, integrated circuits and biological specimens. By harnessing fourth-generation synchrotron radiation, X-ray-free electron lasers, high-harmonic generation, electron microscopes, optical microscopes, cutting-edge detectors and deep learning, CDI and ptychography are poised to make even greater contributions to multidisciplinary sciences in the years to come.

Strong, ductile, and hierarchical hetero-lamellar-structured alloys through microstructural inheritance and refinement

The strength-ductility trade-off exists ubiquitously, especially in brittle intermetallic-containing multiple principal element alloys (MPEAs), where the intermetallic phases often induce premature failure leading to severe ductility reduction. Hierarchical heterogeneities represent a promising microstructural solution to achieve simultaneous strength-ductility enhancement. However, it remains fundamentally challenging to tailor hierarchical heterostructures using conventional methods, which often rely on costly and time-consuming processing. Here, we report a multiscale microstructural inheritance and refinement strategy to process "structural hierarchy precursors" in as-cast heterogeneous Al0.7CoCrFeNi MPEAs, which lead directly to a hierarchical hetero-lamellar structure (HLS) after simple rolling and annealing. Interestingly, it takes only 10 min of annealing time, two orders of magnitude less than that required to render the state-of-the-art properties during conventional processing of Al0.7CoCrFeNi, for us to achieve record-high strength-ductility combinations via the hierarchical HLS design that sequentially stimulates multiple unusual deformation and reinforcement mechanisms. In particular, the HLS-enabled high hetero-deformation-induced (HDI) internal stress triggers profuse <111>-type dislocations on over five independent slip systems in the supposedly brittle intermetallic phase and activates extensive stacking faults (SFs) and nanotwinning in the adjoining soft phase with a rather high SF energy. These unexpected, dynamically reinforcing hetero-deformation mechanisms across multiple length scales facilitate high sustained HDI strain hardening, along with a salient microcrack-mediated extrinsic ductilization effect, suggesting that the proposed microstructural inheritance and refinement strategy provides an efficient, fast, and low-cost approach to overcome the strength-ductility trade-off in a broad range of structural materials.

Coupled Stacking Faults in Silver Nanorods for CO2 Electroreduction.

The interaction of defects has been proven effective in regulating the mechanical properties of structural materials, while its influence on the physicochemical performance of functional materials has been rarely reported. Herein, we synthesized Ag nanorods with dense stacking faults and investigated how the defect interaction affects the catalytic properties. We found that the stacking faults can couple with each other to form a unique structure of opposite atoms with extortionately high tensile strain. Experimental and theoretical analyses reveal that the opposite-atom structure facilitates the adsorption and activation of CO2 molecules, thus improving the catalytic performance of the carbon dioxide electroreduction reaction (CO2RR). As a result, Ag nanorods achieve high CO partial current density (-11.87 mA cm-2 at -0.8 V vs RHE) and high Faraday efficiency (>95%), superior to most Ag-based catalysts. Our work indicates that the defect interaction is an effective means to boost the performance of functional materials.

Materials for the manufacture of dental implants (literature review)

The purpose of this study was to analyze various literature sources, giving an exhaustive overview of the characteristics of all structural materials currently used in the manufacture of dental implants, which will also determine the trend of new developments in materials science in dental implantology. The research material included literary data presented in scientific publications indexed in the bibliographic databases PubMed, ScienceDirect and E-library, using the keywords isolated and their combinations in Russian and English « dental implants, titanium, zirconium, ceramics, tantalum, biocompatibility, osteointegration, graphene» as search terms. The results showed that the use of all existing materials and technological processes for the production of dental implants is justified. To date, the task of further scientific research in this field is to search for and/ or create a material that meets all the necessary operational requirements for a dental implant, has greater biocompatibility, less toxic effects on the body or its absence, providing optimal functional and aesthetic properties, at the lowest possible cost of manufacturing the product. Studies of ceramic-metal materials with the addition of graphene are promising, as currently studies show its high potential acceptability for integration in the development of new materials and technological processes for the production of dental implants.

Dual heteroatom-doped porous biochar from chitosan/lignosulfonate gels for enhanced removal of tetracycline by persulfate activation: Performance and mechanism.

Rational design of carbon material structures is essential for enhancing the performance of persulfate-based advanced oxidation processes (PS-AOPs) in water purification. In this study, a self-doping and self-templating strategy was devised to produce N, S co-doped biochar catalysts through pre-cryocrushing and carbonization procedures employing chitosan (N-source) and lignosulfonate (S-source) derived from biomass waste. The as-synthesized materials exhibited excellent performance in removing tetracycline (TC) through a synergistic process of adsorption and catalytic activation. Mechanistic studies confirmed that electron transfer serves as the primary pathway, while singlet oxygen plays an auxiliary role. Furthermore, the toxicity of the degradation system, the impact of the complex water matrix, and the reusability of the catalysts were thoroughly investigated. Overall, this work is devoted to the treatment and application of biomass waste, which provides a feasible method for synthesizing heteroatom-doped biochar and offers valuable insights into the critical role of heteroatom-doped carbocatalysts in non-radical activation of persulfate.

Nonlinear Optics in Two-Dimensional Magnetic Materials: Advancements and Opportunities.

Nonlinear optics, a critical branch of modern optics, presents unique potential in the study of two-dimensional (2D) magnetic materials. These materials, characterized by their ultra-thin geometry, long-range magnetic order, and diverse electronic properties, serve as an exceptional platform for exploring nonlinear optical effects. Under strong light fields, 2D magnetic materials exhibit significant nonlinear optical responses, enabling advancements in novel optoelectronic devices. This paper outlines the principles of nonlinear optics and the magnetic structures of 2D materials, reviews recent progress in nonlinear optical studies, including magnetic structure detection and nonlinear optical imaging, and highlights their role in probing magnetic properties by combining second harmonic generation (SHG) and multispectral integration. Finally, we discuss the prospects and challenges for applying nonlinear optics to 2D magnetic materials, emphasizing their potential in next-generation photonic and spintronic devices.

Achieving improved dynamic mechanical properties in twinning-dominated titanium alloys

Structural materials with low densities and high-strain-rate properties are of significant importance for the armor applications. Titanium and titanium alloys offer great potential in this regard but typically suffer from localized instability deformation during dynamic loadings. Here, we show that enhanced dynamic mechanical properties are attained in a twinning-dominated titanium alloy Ti-15Mo during split Hopkinson pressure bar tests. Under these tests, the solution treated specimens exhibit superior strain hardening capabilities compared to those of the solution treated plus aging specimens. Benefiting from this, the formation of the adiabatic shear bands (ASBs) and the subsequent material failure are delayed. The deformation-producing heat calculation suggests that the temperature rise is not a major origin of the adiabatic shearing. Yet, the strain localization associated with the non-uniform plastic deformation accounts for more. Microstructural characterizations indicate that the {332}<113> twinning, acting as a predominant deformation mode, improves the strain hardening capabilities of the Ti-15Mo alloy. With the increased strain rate, the increasing trend of the twin density gradually decreases, resulting in the grain boundary separations or even the formation of the ASBs at 4060 /s. The ASB’s shear zone has a density of dynamically recrystallized β grains with maximal hardness but poor strain hardening capability, while the adjacent transition zone experiences a highly localized shear deformation accompanied by the ASB widening. On the basis of these results, the impacts of the twinning on the microstructures and mechanical properties of the Ti-15Mo/Ti-15Mo laminated target plates after penetration experiments are discussed. We believe that titanium alloys with distinguished twinning effect can inspire their widespread applications in military fields.