Class Of Materials Research Articles

Phase Coexistence Induced Giant Dielectric Tunability and Electromechanical Response in PbZrO3 Epitaxial Thin Films.

PbZrO3 (PZO) thin films, as a classic antiferroelectric material, have attracted tremendous attention for their excellent dielectric, electromechanical, and thermal switching performances. However, several fundamental questions remain unresolved, particularly the existence of an intermediate phase during the transition from the antiferroelectric (AFE) to ferroelectric (FE) state. Here, a phase coexistence configuration of an orthorhombic AFE phase and a tetragonal-like (T-like) phase is reported in epitaxial antiferroelectric PZO thin films, with thickness ranging from 16 to 110nm. This configuration is evidenced both macroscopically by distinct shoulder-cape-shaped dielectric behavior and microscopically through scanning transmission electron microscopy (STEM) analysis. Remarkably, a 49nm PZO film achieves an ultrahigh dielectric tunability of 90.1%, while a 59nm film exhibits significant electromechanical strain of 0.66%. Microscopically, HAADF-STEM reveals the presence of the intermediate phase with a dipole arrangement of vertically diagonal up-up-down-down pattern, and first-principles calculations further confirm the role of this intermediate phase during AFE-to-FE phase transition, which is responsible for the unusual dielectric peaks of ɛr-E curves. These findings not only enhance the understanding of phase transition in antiferroelectric materials but also exhibit great potential for high-performance tunable and nano-electromechanical device applications.

3D polycatenated architected materials.

Architected materials derive their properties from the geometric arrangement of their internal structural elements. Their designs rely on continuous networks of members to control the global mechanical behavior of the bulk. In this study, we introduce a class of materials that consist of discrete concatenated rings or cage particles interlocked in three-dimensional networks, forming polycatenated architected materials (PAMs). We propose a general design framework that translates arbitrary crystalline networks into particle concatenations and geometries. In response to small external loads, PAMs behave like non-Newtonian fluids, showing both shear-thinning and shear-thickening responses, which can be controlled by their catenation topologies. At larger strains, PAMs behave like lattices and foams, with a nonlinear stress-strain relation. At microscale, we demonstrate that PAMs can change their shapes in response to applied electrostatic charges. The distinctive properties of PAMs pave the path for developing stimuli-responsive materials, energy-absorbing systems, and morphing architectures.

Temperature‐Dependent Charge‐Carrier Dynamics in Lead‐Halide Perovskites: Indications for Dynamic Disorder Dominated Scattering Mechanism

AbstractLead‐halide perovskites have emerged as a promising material class in light‐harvesting and light‐emitting applications due to their exceptional semiconductor properties. Nonetheless, crucial semiconducting properties such as the charge carrier scattering mechanism and its impact on recombination dynamics are not well studied. Here, five different lead‐halide perovskite compositions are systematically examined to determine their temperature‐dependent mobility, and the prevalent scattering mechanisms involved are identified. Dynamic disorder is proposed to be the predominant scattering mechanism at room temperature and above, as evidenced by a change in the power‐law Tm. Notably, the onset temperature for this behavior varies with the perovskite composition. Additionally, it is found that this scattering process coincides with changes in fast‐trapping behavior in MAPbI3 perovskite, which in turn alters recombination dynamics such as carrier lifetime and diffusion length. These results suggest that this scattering mechanism contributes to the defect tolerance of perovskites, providing valuable insights for further investigations.

Research on the Classification of Traditional Building Materials in Southern Fujian Using the Reflection Intensity Values of Ground-Based LiDAR

Ground-based LiDAR technology has been widely applied in various fields for acquiring 3D point cloud data, including spatial coordinates, digital color information, and laser reflectance intensities (I-values). These datasets preserve the digital information of scanned objects, supporting value-added applications. However, raw point cloud data visually represent spatial features but lack attribute information, posing challenges for automated object classification and effective management. Commercial software primarily relies on manual classification, which is time-intensive. This study addresses these challenges by using the laser reflectance intensity (I-value) for automated classification. Boxplot theory is applied to calibrate the data, remove noise, and establish polynomial regression equations correlating intensity with scanning distances. These equations serve as attribute functions for classifying datasets. Focusing on materials in traditional Minnan architecture on Kinmen Island, controlled indoor experiments and outdoor case studies validate the approach. The results show classification accuracies of 74% for wood, 98% for stone, and 93% for brick, demonstrating this method’s effectiveness in enhancing point cloud data applications and management.

The Analysis of Conductive Polymer Materials

In recent years, more and more researchers have begun to focus on the study of conductive polymer materials, which not only breaks the traditional cognition that polymer materials are insulators, but also their excellent performance makes them applicable in many aspects. In this paper, a literature review research method will be used to introduce the classification, conducting mechanism, preparation methods and practical applications of conductive polymer materials, based on the research conducted by scientific researchers in recent years. This paper will also combine relevant literature to provide a forecast of their future development. Through research, the paper finds that conductive polymer materials, as a new type of conductive material, have shown great potential in many fields and have broad development prospects in the future. Currently, conductive polymer materials have made considerable contributions in the fields of electronic devices, flexible electronics, sensing technology, and biomedicine. Although conductive polymer materials have made certain progress in many fields, there are still many challenges to be overcome in their development. In the future, with the development of materials science and nanotechnology, conductive polymer materials will achieve breakthroughs in more fields and achieve more widespread applications.

Large Improvements in the Thermoelectric Properties of SnSe by Fast Cooling

As reported during the last five years, SnSe is one of the leading thermoelectric (TE) materials with a very low lattice thermal conductivity. However, its elements are not as heavy as those of classical thermoelectric materials like PbTe or Bi2Te3. Its outstanding TE properties were revealed after repeated purification steps to minimize the amount of oxygen contamination, followed by spark plasma sintering. Recently, we showed that hot-pressing—once optimized—can yield comparable or even better TE performance using the examples of Na- and Cu- as well as Na- and Ag-co-doped SnSe. However, long-term stability remains a challenge during cycling between low and high temperatures. Here, we investigated whether the cooling procedure has a significant impact on the thermoelectric properties of SnSe. We compared cooling of the melt with a 1:1 ratio of Sn:Se from 1273 K down to room temperature in air with quenching in water. As typical for undoped SnSe, both materials were extrinsic p-type semiconductors due to Sn defects. The air-quenched sample exhibited higher thermal conductivity, lower electrical conductivity, and higher Seebeck coefficient, all consistent with a smaller number of defects and thus a smaller number of charge carriers due to the slower cooling procedure. This resulted in a comparatively low peak figure-of-merit value zT of 0.61 at 823 K for the air-quenched sample, compared to the substantially higher peak zT of 1.58 at 813 K for the water-quenched sample.

Determination of intrinsic scattering and absorption coefficients of light diffusing materials: application of a spectral projected gradient method

We explore a novel method to obtain scattering and absorption (S&A) coefficients of inhomogeneous materials from measurements of regular transmittance and specular reflectance. We use a Spectral Projected Gradient Method (SPGM) to invert experimental spectra. The SPGM method requires an initial approximation to the S&A coefficients, which is needed to ensure convergence to an optimized solution. We discuss problems associated with multiple solutions and conditions for the obtained optimal solution to be a good approximation to the physical one. We present results for TiO2/polyvinylpyrrolidone (PVP)-water, plasmonic Au/PVP-water and ferromagnetic Fe3O4/PVP-water materials. The obtained S&A coefficients indicate that these materials are dilute suspensions of dense particle clusters in the dependent scattering regime. We argue that the SPGM gives physically realistic solutions for this class of materials. The SPGM has the advantages that it is much less expensive in computational terms and easier to implement than previously used simulated annealing methods.

Conventional Thermoset Composites and Their Sustainable Alternatives with Vitrimer Matrix—Waste Management/Recycling Options with Focus on Carbon Fiber Reinforced Epoxy Resin Composites

Carbon-fiber-reinforced polymers (CFRPs) with epoxy matrices are widely applied in high-performance structural applications and represent one of the biggest classes of materials with urgent need for end-of-life management. Available waste management methodologies for conventional thermoset composites with a focus on CFRPs are briefly reviewed and their limitations are highlighted. In the quest to obtain materials with mechanical performance, thermal stability, and sustainability, the research community has turned its interest to develop polymer composites with adaptable and dynamic networks in their matrix, and lately also at an interface/interphase level. The current review focuses on the life extension/waste management options that are opened through the introduction of covalent adaptable networks in the epoxy matrix of CFRPs. The processing conditions that are applied for the healing/repairing, welding/reshaping, and/or recycling of CFRPs are presented in detail, and compared based on the most common dynamic exchange reactions.

Flat-Band Electronic Bipolarity in a Janus and Kagome van der Waals Semiconductor Nb3TeI7.

Janus materials, a novel class of materials with two faces of different chemical compositions and electronic polarities, offer significant potential for various applications with catalytic reactions, chemical sensing, and optical or electronic responses. A key aspect for such functionalities is face-dependent electronic bipolarity, which is usually limited by the chemical distinction of terminated surfaces and has not been exploited in the semiconducting regime. Here, it is showed that a Janus and Kagome van der Waals (vdW) material Nb3TeI7 has ferroelectric-like coherent stacking of the Janus layers and hosts strong electronic bipolar states in the semiconducting regime. A large potential difference of ∼ 0.7eV between the I4 and TeI3 terminated surfaces is observed, despite only one fourth of the I atoms being replaced by Te atoms on one side of the layers. Additionally, robust semiconducting properties with the face-dependent n-type and p-type field-effect transistor behaviors are demonstrated. These unique properties are attributed to Nb 4d orbital flat bands of the breathing-Kagome lattice, of which significantly large electron mass makes the semiconducting properties immune to impurity doping, and inherent strong electron correlation enhances asymmetric electron distribution, thereby amplifying a built-in electric field. These findings highlight that naturally-grown Janus and Kagome vdW semiconductors provide a promising material platform for utilizing strong electronic bipolarity in 2D-material-basedapplications.

Neuron‐Inspired Biomolecular Memcapacitors Formed Using Droplet Interface Bilayer Networks

AbstractBrain‐inspired (or neuromorphic) computing circumvents costly bottlenecks in conventional Von Neumann architectures by collocating memory and processing. This is accomplished through dynamic material architectures, strengthening or weakening internal conduction pathways similar to synaptic connections within the brain. A new class of neuromorphic materials approximates synaptic interfaces using lipid membranes assembled via the droplet interface bilayer (DIB) technique. These DIB membranes have been studied as novel memristors or memcapacitors owing to the soft, reconfigurable nature of both the lipid membrane geometry and the embedded ion‐conducting channels. In this work, a biomolecular approach to neuromorphic materials is expanded from model synapses to a charge‐integrating model neuron. In these serial membrane networks, it is possible to create distributions of voltage‐sensitive gates capable of trapping ionic charge. This trapped charge creates transmembrane potential differences that drive changes in the system's net capacitance through electrowetting, providing a synaptic weight that changes in response to the history and timing of input signals. This fundamental change from interfacial memory (dimensions of the membrane) to internal memory (charge trapped within the droplets) provides a functional plasticity capable of multiple weights, longer‐term retention roughly an order of magnitude greater than memory stored in the membranes alone, and programming‐erasure.

Synthetic biology meets Aspergillus: engineering strategies for next-generation organic acid production.

Organic acids constitute a vital category of chemical raw materials. They have extensive applications in industries such as polymers, food, and pharmaceuticals. Currently, industrial production predominantly relies on microbial fermentation. Aspergillus, due to its unique metabolic capabilities, has become an important microbial resource for organic acid production. In recent years, there has been a growing emphasis on genetic engineering of Aspergillus to increase its yield of organic acids. This review provides a comprehensive overview of the current advancement and future directions in the application of genetic engineering techniques to enhance organic production in Aspergillus, specifically highlighting achievement in reconstructing metabolic pathways for desired products, eliminating by-products, modifying regulatory pathways, and engineering mycelial morphology. Furthermore, this review also focuses on the strategies and genetic tools applied in Aspergillus, with particular emphasis on the potential applications and challenges of CRISPR-based biosensors in organic acid fermentation. By providing insights into these developments, we aim to offer theoretical guidance and innovative approaches for enhancing the efficiency of Aspergillus strains in industrial organic acid production.

A Low-Symmetry Copper Benzenehexathiol Coordination Polymer with In-Plane Electrical Anisotropy.

Electrically conductive coordination polymers (ECCPs), particularly those incorporating benzenehexathiol (BHT) ligands, are emerging as a distinctive class of electronic materials with tunable semiconducting and metallic properties. However, the exploration of novel ECCPs with low-symmetry structures and electrical anisotropy remains under development. Here, we report the on-water surface synthesis of a novel ECCP, namely Cu5BHT, which exhibits a low-symmetry structure and unique in-plane electrical anisotropy that differs from the well-known Cu3BHT phase. Utilizing imaging and diffraction techniques, we elucidate the unit cell and crystal structure of Cu5BHT, revealing an asymmetric arrangement of the kagome resembling lattice connected by two different secondary building units: square planar CuS4 and non-planar Cu2S4. Theoretical studies indicate that Cu5BHT is metallic and exhibits in-plane electrical anisotropy due to the structure arranged in interconnected well-conducting CuS4 chains and less-conducting Cu2S4 slabs oriented along single crystal direction. Single-crystal electrical measurements confirm a metallic character characterized by the increase of conductance upon cooling. Notably, the measured conductance along different crystal directions within the ab plane unambiguously reveals a significant anisotropy, with an anisotropic factor reaching ~8. This work demonstrates a novel low-symmetry ECCP and highlights its potential for achieving in-plane electrical anisotropy.

A Low‐Symmetry Copper Benzenehexathiol Coordination Polymer with In‐Plane Electrical Anisotropy

Electrically conductive coordination polymers (ECCPs), particularly those incorporating benzenehexathiol (BHT) ligands, are emerging as a distinctive class of electronic materials with tunable semiconducting and metallic properties. However, the exploration of novel ECCPs with low‐symmetry structures and electrical anisotropy remains under development. Here, we report the on‐water surface synthesis of a novel ECCP, namely Cu5BHT, which exhibits a low‐symmetry structure and unique in‐plane electrical anisotropy that differs from the well‐known Cu3BHT phase. Utilizing imaging and diffraction techniques, we elucidate the unit cell and crystal structure of Cu5BHT, revealing an asymmetric arrangement of the kagome resembling lattice connected by two different secondary building units: square planar CuS4 and non‐planar Cu2S4. Theoretical studies indicate that Cu5BHT is metallic and exhibits in‐plane electrical anisotropy due to the structure arranged in interconnected well‐conducting CuS4 chains and less‐conducting Cu2S4 slabs oriented along single crystal direction. Single‐crystal electrical measurements confirm a metallic character characterized by the increase of conductance upon cooling. Notably, the measured conductance along different crystal directions within the ab plane unambiguously reveals a significant anisotropy, with an anisotropic factor reaching ~8. This work demonstrates a novel low‐symmetry ECCP and highlights its potential for achieving in‐plane electrical anisotropy.

Role of Competing Magnetic Exchange on Non-Collinear to Collinear Magnetic Ordering and Skyrmion Stabilization in Centrosymmetric Hexagonal Magnets.

Topological magnetic skyrmions with helicity state degrees of freedom in centrosymmetric magnets possess great potential for advanced spintronics applications and quantum computing. Till date, the skyrmion study in this class of materials mostly remains focused to collinear ferromagnets with uniaxial magnetic anisotropy. Here, we present a combined theoretical and experimental study on the competing magnetic exchange-induced evolution of noncollinear magnetic ground states and its impact on the skyrmion formation in a series of centrosymmetric hexagonal noncollinear magnets, MnFe1-xCoxGe. We show that by engineering the Fe/Co ratio, the system progressively transforms from a noncollinear magnetic state with in-plane antiferromagnetic ordering in MnFeGe to a collinear ferromagnetic (FM) spin arrangement in MnFe0.2Co0.8Ge. We utilize Lorentz transmission electron microscopy, neutron diffraction experiments, and micromagnetic simulations to demonstrate the role of competing magnetic exchange-induced in-plane magnetic moment in the formation of nontopological type-II magnetic bubbles in the system. However, skyrmions with degenerate helicity states are found to be stable magnetic entities in the case of the perfect uniaxial magnetic anisotropy system. The present study offers a great opportunity to tune the skyrmion phase in centrosymmetric magnets by intrinsically designing the magnetic ground state, thereby providing a unique platform for realizing skyrmion-based spintronics devices.

Glass/Polyester Laminates Modified with L-Arginine Phosphate—Effects on the Flammability and Smoke Emission

Flammability and smoke generation of glass-fiber-reinforced polyester laminates (GFRPs) modified with L-arginine phosphate (ArgPA) have been investigated. The composition, structure, and thermal degradation processes of ArgPA were assessed by the elemental, FTIR, and thermogravimetric analyses. Flammability and smoke emission of GFRPs varying by different amounts (5–15 wt.%) of bio-based flame retardant (FR) prepared via hand lay-up method were assessed in terms of the limiting oxygen index (LOI) and smoke density tests. It was observed that the addition of ArgPA results in the formation of a charred layer with visible bubbles. The LOI of GFRP with 15 wt.% of ArgPA increased from 20.73 V/V % (non-modified GFRP) to 24.55 V/V %, and the material classification was improved from combustible to self-extinguishing. FRs usually increase the specific optical density of smoke, which was also observed for ArgPA-modified GFRPs. However, the specific optical density of smoke at the 4th minute of measurement (Ds(4)) obtained for ArgPA-modified GFRPs was lower than for GFRPs modified with commercially used APP. TG/FTIR studies of resin modified with ArgPA revealed the presence of phosphorus compounds and non-combustible gases in the decomposition products. Results demonstrate the potential of ArgPA as an effective, bio-based FR for the enhancement of GFRP fire safety.

Therapeutic functions of medical implants from various material categories with integrated biomacromolecular systems

Therapeutic functions of medical implants from various material categories with integrated biomacromolecular systems

Small-molecule organic ice microfibers.

Small organic molecules are essential building blocks of our universe, from cosmic dust to planetary surfaces to life. Compared to their well-known gaseous and liquid forms that have been extensively studied, small organic molecules in the form of ice at low temperatures receive much less attention. Here, we show that supercooled small-molecule droplets can be drawn into highly uniform amorphous ice microfibers with lengths up to 5 cm and diameters down to 200 nm. In the experimental test, these fiber-like ices manifest excellent mechanical flexibilities with elastic strain up to 3.3%. Meanwhile, they can guide light with loss down to 0.025 dB/cm that approaches the material absorption limit and offer high optical nonlinearity for low-threshold supercontinuum generation. Notable temperature-dependent Young's modulus and icing-induced refractive-index increase are also found. These results may open a promising category of low-temperature materials for both scientific research and technological applications.

Guidance on biomaterials for periodontal tissue regeneration: Fabrication methods, materials and biological considerations.

Regeneration of the multiple tissues and interfaces in the periodontal complex necessitates multidisciplinary evaluation to establish structure/function relationships. This article, an initiative of the Academy of Dental Materials, provides guidance for performing chemical, structural, and mechanical characterization of materials for periodontal tissue regeneration, and outlines important recommendations on methods of testing bioactivity, biocompatibility, and antimicrobial properties of biomaterials/scaffolds for periodontal tissue engineering. First, we briefly summarize periodontal tissue engineering fabrication methods. We then highlight critical variables to consider when evaluating a material for periodontal tissue regeneration, and the fundamental tests used to investigate them. The recommended tests and designs incorporate relevant international standards and provide a framework for characterizing newly developed materials focusing on the applicability of those tests for periodontal tissue regeneration. The most common methods of biofabrication (electrospinning, injectable hydrogels, fused deposition modelling, melt electrowriting, and bioprinting) and their specific applications in periodontal tissue engineering are reviewed. The critical techniques for morphological, chemical, and mechanical characterization of different classes of materials used in periodontal regeneration are then described. The major advantages and drawbacks of each assay, sample sizes, and guidelines on specimen preparation are also highlighted. From a biological standpoint, fundamental methods for testing bioactivity, the biocompatibility of materials, and the experimental models for testing the antimicrobial potential are included in this guidance. In conclusion, researchers performing studies on periodontal tissue regeneration will have this guidance as a tool to assess essential properties and characteristics of their materials/scaffold-based strategies.

Investigating thermodynamic and magnetic behavior of graphullerene-like nanostructure using Monte Carlo techniques

ABSTRACT In the world of carbon-based materials, the effective synthesis of a graphullerene-like nanostructure with remarkable features is a noteworthy accomplishment. This insight holds great promise for advancing the development of a new category of materials. In this study, we examined the thermodynamic characteristics and magnetocaloric effects of a structure resembling graphullerene using Monte Carlo simulations. The current study provides a detailed analysis of how Hamiltonian parameters impact the thermodynamic properties and magnetocaloric quantities of the system. Moreover, our findings indicate that adjusting the magnetic field not only allows for critical regulation of temperature but also has a notable impact on magnetocaloric characteristics. This includes changes in magnetic entropy and the relative cooling capacity. Based on our results, it is strongly suggested that the graphullerene-like nanostructure holds great promise as a candidate for applications in magnetic refrigeration.

Control of Permanent Porosity in Type 3 Porous Liquids via Solvent Clustering.

Porous liquids (PLs) are an exciting new class of materials for carbon capture due to their high gas adsorption capacity and ease of industrial implementation. They are composed of sorbent particles suspended in a nonadsorbed solvent, forming a liquid with permanent porosity. While PLs have a vast number of potential compositions based on the number of solvents and sorbent materials available, most of the research has been focused on the selection of the sorbent rather than the solvent. Therefore, PL design criteria on the supramolecular structures of the solvent are explored to create a fundamental understanding of how the solvent enables PL formation for rapid discovery of new PL compositions. Atomistic molecular dynamics simulation of eight solvents with a range of molecular sizes, shapes, and intramolecular bonding was performed, identifying that the shape and size of molecular clusters formed in the solvent are the driving predictor of PL formation rather than the size of the individual solvent molecule. The results demonstrate a significant departure from common approaches to PL formation based on the steric exclusion of solvent molecules from the sorbent via the size of the pore aperture. A modeling and experimental validation study further supports these findings. Through this computational material design study, a previously unexplored mechanism in PL formation, solvent-solvent clustering, is identified as a critical factor for the accelerated discovery of liquid phase carbon capture materials.