Composite Technology Research Articles

Compositional and Hollow Engineering of Silicon Carbide/Carbon Microspheres as High-Performance Microwave Absorbing Materials with Good Environmental Tolerance

HighlightsHollow SiC/C microspheres with controllable composition have been successfully synthesized by simultaneously implementing compositional and structural engineering.The optimum dielectric properties (i.e., conductivity loss and polarization loss) and impedance matching characteristics can achieve outstanding microwave absorption performance.Broadband wave absorption (5.1 GHz with only 1.8 mm thickness), high efficiency loss (− 60.8 dB at 10.4 GHz) combined with good environmental tolerance, demonstrate their bright prospects in practice.

Composition Engineering on the Structure and Transport Properties of CaO–SiO2–P2O5 System: A Computational Insight

Composition Engineering on the Structure and Transport Properties of CaO–SiO2–P2O5 System: A Computational Insight

Mixed cations tin-germanium perovskite: A promising approach for enhanced solar cell applications

Significant progress has been made over the years to improve the stability and efficiency of rapidly evolving tin-based perovskite solar cells (PSCs). One powerful approach to enhance the performance of these PSCs is through compositional engineering techniques, specifically by incorporating a mixed cation system at the A-site and B-site structure of the tin perovskite. These approaches will pave the way for unlocking the full potential of tin-based PSCs. Therefore, in this study, a theoretical investigation of mixed A-cations (FA, MA, EA, Cs) with a tin-germanium-based PSC was presented. The crystal structure distortion and optoelectronic properties were estimated. SCAPS 1-D simulations were employed to predict the photovoltaic performance of the optimized tin-germanium material using different electron transport layers (ETLs), hole transport layers (HTLs), active layer thicknesses, and cell temperatures. Our findings reveal that EA0.5Cs0.5Sn0.5Ge0.5I3 has a nearly cubic structure (t = 0.99) and a theoretical bandgap within the maximum Shockley-Queisser limit (1.34 eV). The overall cell performance is also improved by optimizing the perovskite layer thickness to 1200 nm, and it exhibits remarkable stability as the temperature increases. The short-circuit current density (Jsc) remains consistent around 33.7 mA/cm2, and the open-circuit voltage (Voc) is well-maintained above 1 V by utilizing FTO as the conductive layer, ZnO as the ETL, Cu2O as the HTL, and Au as the metal back contact. This configuration also achieves a high fill factor ranging from 87 % to 88 %, with the highest power conversion efficiency (PCE) of 31.49 % at 293 K. This research contributes to the advancement of tin-germanium perovskite materials for a wide range of optoelectronic applications.

Obtaining versatile Cr3+-activated phosphors with improved far-red emissions via host composition modulation

Cr3+-activated spinel-type phosphors have great potential in different application scenes due to their unique sharp and far-red (FR) emission. However, the multi-functionalization of these phosphors is still limited by their unsatisfied comprehensive properties. Herein, a simple composition engineering was used to explore versatile phosphors, using Ga3+ to substitute Al3+ to improve the optical performances of spinel LiAl5–xGaxO8:Cr3+. The substitution of Ga3+ evidently affects the crystal field environment of Cr3+ and further accounts for the luminescence optimization. Using the optimized phosphor, two sensitive thermometers based on fluorescence intensity ratio (FIR) technique were explored on account of the different temperature dependencies of 4T2→4A2 and 2E→4A2 emission and of R2 and R1 emission. The maximum relative sensitivity Sr are 1.29%/K at 323 K and 1.94%/K at 298 K, respectively, which are superior to that of the Ga3+-unsubstituted one. Besides, the Ga3+→Al3+ substitutions endow the resultant phosphors with larger atomic number (Zeff) and theoretical density, which is more conducive to improving X-ray-stimulated emission for X-ray detection. Finally, the potential applications of the developed phosphor are also reflected in plant growth and night vision surveillance, as it is shown to be capable of matching with the absorption of phytochrome PFR and visualizing objects in the dark. This contribution not only proves that the developed LiAl5–xGaxO8:Cr3+ FR phosphors are promising versatile platforms, but also provides an essential guidance for designing more novel multi-functional materials.

Analysis of load-bearing characteristics of bi-modulus composite stiffened plates: Numerical simulation method and large-scale experimental verification

A large number of experiments show that composite materials usually show different modulus properties in tension and compression (bi-modulus). However, for actual composite engineering structures, especially complex models, the numerical simulation calculation is usually based on a single modulus. In order to consider the different modulus characteristics of composite materials in tension and compression, researchers put forward simplified constitutive models of dual-modulus materials. However, these constitutive models have not been verified by a large number of experiments, especially by complex models. In this paper, the GWFMM model is simplified and used to analyze complex structures with different modulus in tension and compression. The experimental results of stiffened plate show that the improved GWFMM model can be used to analyze different modulus of tension and compression of complex stiffened structures. In addition, the influence of elastic modulus ratio in tension and compression under different experimental load conditions is further explored, and the influence law of bending and torsion on structures with bi-modulus is discussed. The relevant conclusions provide reference for the design and optimization of full-scale composite structures in marine engineering.

Research Progress of β-Ketoenamine-Linked Covalent Organic Frameworks for Photocatalytic Hydrogen Evolution

β-Ketoamide covalent organic frameworks (COFs), also named Tp-COFs, are considered to be a milestone material in the history of photocatalysts because of their excellent visible-light absorption, high crystallinity, ultra-high stability and structural diversity. In recent years, a large number of Tp-COFs and their composites have been successfully constructed based on molecular or composite engineering strategies, and exhibited splendid photocatalytic water splitting activity. In comparison with a composite strategy, the molecular engineering technique effectively avoids interface problems by designing and preparing frameworks at the molecular level. Therefore, it is necessary to timely summarize the construction of Tp-COF photocatalysts based on the molecular engineering strategy, so as to provide some theoretical basis and enlightenment for the subsequent development of high-performance Tp-COFs. Finally, the shortcomings and challenges of this technique and personal views on the further development of Tp-COFs are presented.

Boosting optoelectronic performance of (FA)X(MA)1-XPbI3 perovskite solar cells: Via FAI post-treatment engineering

Complex composition engineering of mixed-cations perovskite (FAxMA1-xPbI3) has recently supported rapid progress in perovskite solar cells (PSCs). Nevertheless, it is insufficient to embed and accommodate formamidinium (FA) cation into the MAPbI3 lattice structure via existing methods, leaving behind masses of FA or lead halide content and deteriorating photovoltaic performance. Herein, we present facile surface engineering via post-treated methodology, the surface of CH3NH3PbI3 (MAPbI3) films post-treated with formamidinium iodide (FAI) solution and that results get mixed-cation FAxMA1-xPbI3 perovskite films. The mixed-cation-based FAXMA1-XPbI3 perovskite with significant and large grain size, uniform and compact morphology, highly crystallization, and consequently reducing defect density of the perovskite films can be produced via the present method. It is observed that the film, post-treated with FAI-2, shows results in a very stable and highly crystalline lattice structure with attributes such as extended carrier lifetime, better electron transport, and decreased defect density. The optimized device demonstrates a promising power conversion efficiency (PCE) of 21.89%, and higher than that of the non-treated (19.08%) devices. Furthermore, the devices based on the novel FAI-post-treatment engineering exhibit significantly enhanced stability compared to non-treated devices. Therefore, this approach provides a novel methodology that offers a simple method for producing superior mixed perovskite films, potentially paving the way for the future exploitation of the boosted performance of perovskite solar cells.

2D/3D structure engineering of dual-phase Mo2C/MoO2-decorated rGO aerogels for electromagnetic waves absorption

The rational design of structure and regulation of composition in micro/nano-scale is of great significance for broadband absorbing properties of lightweight aerogels. Herein, the controllable dual phase Mo2C/MoO2-decorated rGO aerogels are prepared by designing the Mo-rGO precursor, which possesses heterostructure interfaces and three-dimensional structures. The dual-phase of Mo2C/MoO2 was controlled and nanoparticles were dispersed on the surface of graphene. The interconnected rGO sheets construct continuous network for electron transport, which facilitates conduction loss and multiple reflections inside the aerogel. The Mo2C/MoO2 nanoparticles decorated on rGO sheets contribute sufficient interfacial and dipole polarization, and improve the impedance matching and strengthen the loss capacity of electromagnetic waves. The as-prepared Mo2C/MoO2/rGO aerogel exhibits considerable electromagnetic wave absorption performance with a minimum reflection loss of −42.1 dB at 12.5 GHz and an effective absorption bandwidth of 5.6 GHz (10.6–16.2 GHz) at a thin thickness of 2.2 mm with a low density of 9.8 mg·cm−3. This Mo2C/MoO2/rGO aerogel would be a promising material for electromagnetic wave absorption in wide application fields, and it also provides a universal idea for constructing low-density broadband microwave absorption material by structural and composition engineering.

High-performance all-solid-state lithium batteries enabled by high-conductivity free-standing sulfide electrolyte membrane and Li-Zn/LiCl bifunctional interphase

All-solid-state lithium batteries (ASSLBs) empolying sulfide solid electrolyte and lithium metal anode can afford improved energy density and safety. However, their large-scale application is hampered by the rigidity of ceramic–based electrolyte and the inevitable growth of lithium dendrites. Herein, a novel, flexible, high-conductivity and free-standing sulfide electrolyte membrane (Li6PS5Cl-polypropylene carbonate6, (LPSCl-PPC6)) with a thickness of 60 μm is prepared via methodology of blade coating and hot pressing, which exhibits a high Li+ conductivity (3.1 × 10−3 S cm−1 at 25 °C) and a wide electrochemical window (4.7 V vs Li+/Li) at 25 °C. Additionally, a bifunctional interphase with Li-Zn/LiCl is implanted on lithium metal surface to enhance the stability of electrolyte/lithium anode, which effectively prevents the growth of lithium dendrites and the internal short circuit of lithium symmetric battery. Benefiting from the synergistic effect, the assembled ASSLBs of S-CNTs/LPSCl-PPC6/Li-Zn/LiCl|Li and LLZO@NCM93/LPSCl-PPC6/Li-Zn/LiCl|Li exhibit high initial capacity of 1183.5 mAh g−1 (193.6 mAh g−1) and exceptionally cyclic stability with capacity retention of 89.2% over 150 cycles at 0.05C (93.2% over 100 cycles at 0.1C). This highly conductive sulfide-based composite electrolyte and interface engineering provides a promising strategy for achieving high performance ASSLBs.

Thermal analysis of a perforated laminated plate with multiple random elliptical holes by specially formulated finite elements

The high-efficient and accurate analysis of anisotropic composite media weakened by a large amount of holes or cuts is still a great challenge in practical composite engineering. In this work, specially-proposed polygonal finite element enclosing an arbitrarily oriented elliptical hole in general anisotropic composite media is formulated for thermal analysis in the framework of hybrid finite element theory. Two independent temperature field approximations are defined for the present special element: Intra-element temperature field and element frame temperature field. The former defined inside the element is written in the form of truncated summation of the weighted special fundamental solutions, which are derived using the Stroh complex theory and conformal mapping whilst the latter is implemented by the conventional shape function interpolation. Then the hybrid variational functional is employed to combine them together to generate an element stiffness equation with respect to nodal temperature and an optional relationship between the interpolation coefficients. The element stiffness matrix is symmetric and involves element boundary integrals only. Compared to the traditional finite element, the distinctive element-boundary-integral and enclosed-elliptical-hole features make the present element significantly improve the meshing effort around an elliptical hole by reducing the number of elements and decreasing the meshing difficulty, and more importantly, effectively capture the critical variation of physical fields around the elliptical hole without locally-refined meshes. Moreover, the present special element can be incorporated directly into the conventional finite element system without any difficulty for extensive analysis. Finally, several typical examples are simulated by the present special elements to demonstrate their effectiveness.

Enhancing the thermodynamic properties of rare-earth niobates through high-entropy and composite engineering

High-entropy rare-earth niobates have garnered significant attention in the field of thermal barrier coatings (TBCs) due to their ultra-low thermal conductivity. However, the exceptional thermal properties of fluorite-phase high-entropy rare-earth niobates and the outstanding mechanical properties of monoclinic-phase high-entropy rare-earth niobates cannot be simultaneously harnessed. To address this limitation, this paper investigates and synthesizes five single-phase high-entropy rare-earth niobates: (RE1/5Ho1/5Er1/5Y1/5Yb1/5)3NbO7 (RE = Ce, Sm, Eu, Dy, Lu), and five composite-phase high-entropy rare-earth niobates with a molar ratio of (RE1/5Ho1/5Er1/5Y1/5Yb1/5)NbO7: (RE1/5Ho1/5Er1/5Y1/5Yb1/5)NbO4 = 1:2 (RE = Ce, Sm, Eu, Dy, Lu). The objective is to fabricate niobate coatings that exhibit both outstanding thermal and mechanical properties.The test results reveal that the intrinsic thermal conductivity of the composite-phase samples stands at a mere 1.46 W m−1·K−1 at 1000 °C. Comparatively, the experimental thermal conductivity of the single-phase samples slightly surpasses that of the composite-phase at 1000 °C, registering a minimum of 1.57 W m−1·K−1. Importantly, both values adhere to the TBC standard. The mechanisms behind the low thermal conductivity of the composite-phase and single-phase samples are elucidated by the phonon scattering mechanism and the Cahill model, respectively. Furthermore, the thermal expansion coefficient of the composite-phase samples exceeds that of the single-phase samples overall, and they demonstrate exceptional mechanical properties, offering nearly twice the fracture toughness of the single-phase samples while maintaining high hardness. Experimental evidence shows that composite-phase niobates exhibit enhanced thermodynamic properties compared to single-phase niobates. This work serves as a valuable reference for the utilization of high-entropy rare-earth niobates in the realm of thermal barrier coatings.

Unraveling the rapid ion migration in perovskite solar cells by circuit-switched transient photoelectric technique.

Ion migration activated by illumination is a critical factor responsible for the performance decline and stability degradation of perovskite solar cells (PSCs). While ion migration has been widely believed to be much slower than charge transport, recent research suggests that, despite the lack of understanding of the mechanism, it may also be involved in a series of rapid photoelectric responses of PSCs. Here, we report an improved circuit-switched transient photoelectric technique with nanosecond temporal resolution, which enables quantitative characterization of ion migration dynamics in PSCs across a fairly broad time window. Specifically, ion migration occurring within microseconds after illumination (corresponding to a diffusion length of ∼10-7cm) is unambiguously identified. In conjunction with the composition engineering protocol, we justify that it arises from the short-range migration of halide anions and organic cations around the contact/perovskite interface. The rapid ion migration kinetics revealed in this work strongly complement the well-established ion migration model, which offers new insights into the mechanism of ion-carrier interaction in PSC devices.

Mn-regulated CuFe2O4 spinel based active component continuous exsolution catalyst for long-term degradation of tetracycline

The development of catalysts with fast reaction rates and long service life remains a significant challenge in advanced oxidation processes. The research applied the property that Mn could occupy both tetrahedral and octahedral sites in the spinel structure. By adjusting Mn composition engineering in CuFe2O4, it could regulate the proportion of active components in spinel constituents and form the hybrid catalyst of Mn-doped CuFe2O4/CuO. CuFe2O4/CuO biphasic interface caused lattice distortion, effectively enhancing the interface interaction, which was conducive to the gradual exsolution and redeposition of the active component CuFe2O4 during the catalytic reaction process, thereby prolonging the service life of the catalyst. Within 30 min, the removal rate of tetracycline hydrochloride was 97.3%, while peroxymonosulfate (PMS) stoichiometric efficiency was 0.12. The degradation effect of the powder catalyst only decreased by 7.3% after 6 cycles. In the self-made fixed bed, the mass ratio of sodium alginate solidified catalyst to sewage treatment capacity could reach 1:33000. These results indicated that Mn doping could effectively improve the catalytic degradation performance of CuFe2O4 and prolong the service life of the catalyst by forming a two-phase interface. Furthermore, sodium alginate curing catalysts could provide new insights into the industrial application of catalysts.

2D/0D multiscale interfacial engineering of carbon fiber composites for simultaneous achieving high mechanical and electromagnetic interference shielding properties

AbstractIn the face of escalating electromagnetic pollution, it is urgently needed to expedite the development of innovative carbon fiber reinforced polymer (CFRP) composites that not only demonstrate superior mechanical properties as well as durability but also boast exceptional electromagnetic interference shielding (EMI) performance. However, given the absence of robust interface interactions and the lack of an outstanding nanostructured conductive network, there remains a need to further elevate the overall performance of CFRP composites. Herein, a highly continuous conductive network by integrating 2D MXene and 0D Ag nanoparticles with strong interlayer interactions was constructed through point‐to‐plane conductive modes, facilitated by polydopamine (PDA). Thanks to the excellent electromagnetic wave loss and the unique multi‐dimensional structure arising from the optimizing interfacial engineering, the EMI shielding effectiveness of the modified CF‐PDA‐M‐Ag/EP composite achieved a remarkable 45.9 dB, obtaining a 99.5% enhancement compared with the neat CF/EP. The synergistic effect resulting from the multi‐dimensional structure and strong interaction can improve the interfacial shear strength (IFSS), interlaminar shear strength (ILSS) and flexure strength of the composite up to 81.9, 85.8 and 864.6 MPa, respectively, far superior to the unmodified composite materials. This research provides a dependable and convenient approach for exploiting high‐performance CFRP composites with intriguing electromagnetic interference (EMI) shielding properties.Highlights An optimizing multifunctional 2D/0D interface for carbon fiber was designed. A highly conductive network via the point‐to‐plane conductive mode. The EMI shielding effectiveness of the composite reached up to 45.9 dB.

Fractographic analysis of fiber‐reinforced polymer laminate composites for marine applications: A comprehensive review

AbstractIn the past decade, polymer‐based glass fiber‐reinforced laminate composites have gained significant popularity in various mass transit applications, including marine, aircraft, and automotive industries. However, it is crucial to consider the degradation and potential failure of these materials, especially in mass transit networks. To address this concern, fractographic analysis has emerged as a valuable approach for investigating fracture surfaces, extracting vital information, and facilitating the development of new materials. Furthermore, it sheds light on the underlying physical mechanisms that contribute to composite failure. This paper primarily focuses on examining flaws, failure modes, and performing fractography analysis on fiber‐reinforced polymer (FRP) laminate composites subjected to various loading conditions such as tension, compression, flexure, impact, shear, and fracture. Fractography, as an indispensable method, plays a pivotal role in the comprehensive development of composite structures and has become a reliable tool for composite engineers. The outcomes of this study are expected to serve as a foundation for identifying areas that require further investigation in terms of fracture analysis and failure modes specific to FRP composite materials, particularly those used in marine applications.Highlights Introduction to FRP laminate composites in marine structures. Concise analysis of failure modes in FRP laminate composites. SEM fractography review of FRP laminate composites under varied loading conditions. Comprehensive study on tensile, flexural, impact, compression, shear, and fracture toughness failure modes. Summarization of identified defects in FRP composites.

Investigation of Composite Materials for Significant Damping Response in Automotive Applications

Through the examination of composite components, engineers and manufacturers can enhance their understanding of failure criteria, the initiation of initial failures, and the propagation of damage within laminates. This study delves into the evolution of impact-induced degradation and establishes upper limits on force or Hertz failure thresholds for three distinct composite categories. Impact investigations reveal that the strength of composite materials significantly increases under dynamic impact conditions compared to static ones, underscoring the material's sensitivity to loading rates. Composite materials play a crucial role in achieving effective ballistic protection for armor platforms, given the varying energy levels of the physical loads they must withstand based on their intended applications. Precise design and manufacturing are necessary to provide adequate protection against impacts of different energies: low-energy impacts from tools during maintenance and operations, intermediate-energy impacts from external elements striking the surface, and high-energy impacts from weapons. Fiber-reinforced composite materials find widespread use across the aviation, marine, and terrestrial industries due to their outstanding specific strength, weight reduction benefits, and ease of manufacturing. They are particularly crucial in aerospace and military applications. Polyester resins offer a cost-effective and easily moldable alternative to epoxy resins in many fiberglass applications. This study aims to explore the low-velocity impact characteristics of E-Glass composites, which are more readily available and cost-effective compared to other reinforced composites. The research focuses on evaluating the impact properties of these materials through testing three different samples.

SDATA: Symmetrical Device Identifier Composition Engine Complied Aggregate Trust Attestation

Efficient safeguarding of the security of interconnected devices, which are often resource-constrained, can be achieved through collective remote attestation schemes. However, in existing schemes, the attestation keys are independent of the device configuration, leading to increased requirements for the trusted computing base. This paper introduces a symmetrical aggregate trust attestation that is compatible with devices adhering to the device identifier composition engine framework. The proposed scheme simplifies the trusted computing base requirements by generating an attestation key that is derived from the device configuration. Moreover, the scheme employs distributed aggregate message authentication codes to reduce both the communication volume within the device network and the size of the attestation report, thereby enhancing the aggregation efficiency. In addition, the scheme incorporates interactive authentication to accurately identify compromised devices.

Optimizing Thermoelectric Properties through Compositional Engineering in Ag-Deficient AgSbTe2 Synthesized by Arc Melting.

Thermoelectric materials offer a promising avenue for energy management, directly converting heat into electrical energy. Among them, AgSbTe2 has gained significant attention and continues to be a subject of research at further improving its thermoelectric performance and expanding its practical applications. This study focuses on Ag-deficient Ag0.7Sb1.12Te2 and Ag0.7Sb1.12Te1.95Se0.05 materials, examining the impact of compositional engineering within the AgSbTe2 thermoelectric system. These materials have been rapidly synthesized using an arc-melting technique, resulting in the production of dense nanostructured pellets. Detailed analysis through scanning electron microscopy (SEM) reveals the presence of a layered nanostructure, which significantly influences the thermoelectric properties of these materials. Synchrotron X-ray diffraction reveals significant changes in the lattice parameters and atomic displacement parameters (ADPs) that suggest a weakening of bond order in the structure. The thermoelectric characterization highlights the enhanced power factor of Ag-deficient materials that, combined with the low glass-like thermal conductivity, results in a significant improvement in the figure of merit, achieving zT values of 1.25 in Ag0.7Sb1.12Te2 and 1.01 in Ag0.7Sb1.12Te1.95Se0.05 at 750 K.

Realization of the Giant Pyroelectric Response via Modulated Polar Structures.

Among pyroelectric materials, Bi0.5Na0.5TiO3 (BNT)-based relaxors are particularly noteworthy due to their significant polarization fluctuation near the depolarization temperature (Td), resulting in a large pyroelectric response. What has been overlooked is the dynamic behavior of inherent polar structures, particularly the temperature-dependent evolution of polar nanoregions (PNRs), which significantly impacts the pyroelectric behavior. Herein, based on the large pyroelectric response origination (the ferroelectric-relaxor phase transition), the mixed nonergodic and ergodic relaxor (NR+ER) critical state is constructed, which is believed to trigger the easily fluctuating polarization state with excellent pyroelectric response. Composition engineering (with Li+, Sr2+, and Ta5+) strategically controls the relaxor process and modulates the dynamic behavior of inherent polar structures by the random field effect. The pyroelectric coefficient of more than 1441 µCm-2K-1 at room temperature (RT), more than 9221 µCm-2K-1 (RT), and ≈107911 µCm-2K-1 (Td) are achieved in the Li+-doped sample, the Sr2+-doped sample, and the (Li++Ta5+) co-doped sample, respectively. This work earns the highest RT pyroelectric coefficient in BNT-based relaxors, which is suitable for pyroelectric applications. Furthermore, it provides a strategy for modulating the pyroelectric performance of BNT-based relaxors.

Improved energy storage performance achieved in (Bi0.5Na0.5)TiO3-based relaxor ferroelectrics via composition engineering

The utilization of relaxor-ferroelectrics is considered to become a feasible scheme to achieve high energy storage performance owing to their high polarization and low hysteresis loss. Herein, the (1-x)(Bi0.5Na0.5)TiO3-x(Sr0.7La0.2)(Ti0.9Zr0.1)O3 ((1-x)BNT-xSLTZ) ceramics were synthesized by using the traditional solid-state reaction method. A favorable recoverable energy density (Wrec) of 4.0 J cm−3 could be obtained at 295 kV cm−1 by combining composition-driven intensive relaxation behaviors and fine grains. Further, the high stabilities for temperature and frequency, with energy density of 1.56–1.41 J cm−3 over a range of 25–150 °C at 150 kV cm−1 and energy density of 1.48–1.67 J cm−3 at 150 kV cm−1 ranging from 1 Hz to 200 Hz, are achieved in 0.6BNT-0.4SLTZ. These results suggest that the BNT-SLTZ relaxor ferroelectric ceramics have capacity of becoming a promising candidate for high-power energy storage applications.