Basal Plane Research Articles

Activating the Basal Plane of 2D Transition Metal Dichalcogenides via High-Entropy Alloying.

Two-dimensional materials, such as transition metal dichalcogenides (TMDCs) in the 2H or 1T crystal phases, are promising (electro)catalyst candidates due to their high surface-to-volume ratio and composition of low-cost, abundant elements. While the edges of elemental TMDC nanoparticles, such as MoS2, can show significant catalytic activity, the basal plane of the pristine materials is notoriously inert, which limits their normalized activity. Here, we show that high densities of catalytically active sites can be formed on the TMDC basal plane by alloying elements that prefer the 2H (1T) phase into a 1T (2H) structure. The global stability of the alloy, in particular, whether it crystallizes in the 2H or 1T phase, can be controlled by ensuring a majority of elements prefer the target phase. We further show that the mixing entropy plays a decisive role in stabilizing the alloy, implying that high-entropy alloying becomes essential. Our calculations point to a number of interesting nonprecious hydrogen evolution catalysts, including (CrTaVHfZr)S2 and (CrNbVTiZr)S2 in the 1T-phase and (MoNbTaVTi)S2 in the 2H-phase. Our work opens new directions for designing catalytic sites via high-entropy alloy stabilization of locally unstable structures.

Regulating Chemical Bonds in Halide Frameworks for Lithium Superionic Conductors.

Developing solid-state electrolytes (SSEs) is a critical task for advancing all-solid-state batteries (ASSBs) that promise a high energy density and improved safety. The dominant strategy in engineering advanced SSEs has been substitutional doping, where foreign atoms are introduced into the atomic lattice of a host material to enhance ionic conduction. This enhancement is typically attributed to optimized charge carriers' concentration or lattice structure alterations. In this study, we extend the concept of substitutional doping to explore its effects on chemical bond modulation and the resulting impact on ionic conduction in halide SSEs. As a case of study, we demonstrate that cation dopants with high charge density indices (e.g., Al3+ and Fe3+) can increase the covalency of metal-halide (M-X) bonds and induce the local asymmetric field of force, resulting in higher site energy and lower migration barriers, which significantly enhance the ionic conduction in halide frameworks. Specifically, we developed a series of halide SSEs with ionic conductivities exceeding the benchmark value of 1 mS cm-1 at room temperature. Detailed investigations, including neutron powder diffraction, pair distribution function analysis, and first-principles calculations, are performed to gain an insight into the mechanisms behind this adjustment. Furthermore, these materials exhibit enhanced deformability due to increased covalency of the metal halide framework, enabling high-performance ASSB prototypes operatable at low stacking pressures (<10 MPa). These advancements deepen our understanding of superionic conduction in halide SSEs and mark an important step toward the practical application of ASSBs in the future.

Investigation and prediction of fatigue performance of SLM 316 L stainless steel based on small build orientation variations and heat treatment effects

Additive manufacturing (3D printing) has facilitated the creation of complex structures, including lattices with diverse build angles. Since lattices often face quasi-static and cyclic loads, understanding material properties across a wide range of printing angles, post-processing conditions, and loading scenarios is crucial. This study explores the effects of building orientations beyond conventional 0, 45, and 90 degrees on the mechanical properties of 316 L steel, produced by laser powder bed fusion. Quasi-static and cyclic tensile tests were performed to evaluate mechanical behavior in as-built and heat-treated conditions, followed by predictive model development. The ultimate strength showed a modest variation of 7% in the as-built condition, while the heat-treated state exhibited a greater variation of 13%. Fatigue tests indicated minor differences between conditions in the low-cycle region but larger gaps in the high-cycle region, where heat-treated samples generally showed superior performance. Inclination angle had a greater effect on fatigue life in the as-built state, with horizontal part orientations outperforming vertical ones. The predictive model demonstrated robust reliability, with nearly 90% of data within an accepted scatter factor of less than three. Requiring minimal experimental data (two fatigue curves per condition), the model is valuable for forecasting fatigue behavior in complex lattice structures.

Enhancement of Energy Absorption Capability of 3D Printed Ti-6Al-4V BCC Lattice Structures by Adding Auxiliary Struts

Enhancement of Energy Absorption Capability of 3D Printed Ti-6Al-4V BCC Lattice Structures by Adding Auxiliary Struts

Plasma-Assisted Synthesis of N-Doped ZnO for Photocatalytic H2O2 Production

Nonthermal plasma is a convenient, efficient and environmentally friendly technology for the synthesis and modification of materials. In this study, microwave plasma, a type of nonthermal plasma, was utilized to facilitate the rapid synthesis of hierarchical porous ZnO materials with N2 as feeding gas. It was observed that ZnO precursor could be transformed into hexagonal ZnO crystals after a short duration of plasma treatment while successfully incorporating N atoms into its lattice structure. The plasma-treated samples exhibit an increased number of smaller mesopores without compromising the hierarchical structure of the ZnO precursor. Furthermore, due to their enlarged specific surface area and extended visible light response range, the N-doped ZnO samples demonstrate excellent performance in photocatalytic H2O2 production performance. This work provides novel insight on exploring a new highly effective and efficient tools for material synthesis.

A First Principle Study to Understand the Importance of Edge-exposed and Basal Plane Defective MoS2 Towards Nitrogen Reduction Reaction.

Nitrogen reduction reaction (NRR) as a promising approach to ammonia synthesis has received much attention in recent years. Herein, by using density functional theory (DFT) calculations, we constructed edge-exposed MoS2 and different kinds of basal plane defects, including anti-site, sulfur vacancy and pore defects, to systematically investigate their influence on the NRR performance. The thermodynamically calculated results revealed that the NRR on edge-exposed MoS2, anti-site defects, sulfur vacancy with three sulfur atoms missing (S3V) and porous defect (D) exhibit great catalytic activity with low limiting potentials. The calculated limiting potentials are -0.43 and -0.47 V at armchair and zigzag edge MoS2, -0.42 and -0.44 V at anti-site defects, -0.49 and -0.67 V at S3V and D. However, by inspecting the thermodynamic properties of the hydrogen evolution reaction, we proposed that the zigzag-end MoS2 and anti-site defects exhibit a better NRR selectivity compared to armchair-end MoS2, S3V and D. Electronic structure calculations reveals that the edge-exposed and basal plane defective MoS2 can improve the conductivity of the material by reducing the band gap. Donation-backdonation mechanism can effectively promote the activation of nitrogen molecule.

Comparison of optical features in nitrobenzene-core PCF with hexagonal and square lattices in the claddings

This paper proposes two novel photonic crystal fibers (PCFs) with a nitrobenzene core, designed using hexagonal and square lattice structures. The characteristics of the PCFs were numerically analyzed in detail and compared to selecting the proposed optimal structure for supercontinuum generation. This study investigates the influence of core diameter (DC) on the characteristics of PCF. The fiber’s nonlinear properties are significantly enhanced by varying the core diameter. The hexagonal PCF structures provide flatter dispersion curves and are closer to zero dispersion than the square lattice, which is beneficial for supercontinuum generation. In contrast, the square PCF structures show higher nonlinear coefficients and lower attenuation than the corresponding hexagonal structures. Based on the simulation results, six optimized structures with all-normal and anomalous dispersion were selected to study the characteristics at the pump wavelength. Results indicate that the proposed PCFs exhibit near-zero flat dispersion, low attenuation and high nonlinearity. The selected optimal structures show potential for efficient supercontinuum generation, enabling broad and highly coherent spectra.

STUDY PHASE STRUCTURE, CATION DISTRIBUTION AND MAGNETIC PROPERTIES OF COBALT, MAGNESIUM AND COPPER FERRITES

An analysis to the characteristics of Co, Mg and Cu ferrites that were prepared using sol–gel method and annealed at [Formula: see text]C for 1 hour, performed using X-ray diffraction and Raman spectroscopy for structural characteristics, while the Vibrating Sample Magnetometer (VSM), was used for the magnetic characteristics. The X-ray analysis of both cobalt and magnesium ferrites shows a reverse crystal structure of a cubic spinel, while copper ferrite shows a tetragonal crystal structure characteristic at this annealing temperature. The lattice constant (a) was found to be [Formula: see text] for CoFe2O4, [Formula: see text] for MgFe2O4 and [Formula: see text] for CuFe2O4. The Raman spectrum confirms a spinel crystalline form of the prepared ferrites where a likely distribution of cation is indicated at the tetrahedral and octahedral sites. The peaks of the Raman shift appear between 200–800[Formula: see text]cm[Formula: see text]. These peaks indicate the formation of ferrites. The hysteresis loop of CoFe2O4 indicates a hard magnet material. Cu ferrites have relatively lower remnants and magnetocrystalline anisotropy, which indicates soft magnetic characteristics even though it showed higher coercivity. The squareness ratio (Mr/Ms) values varied between 0.52, 0.13 and 0.57 for CoFe2O4, MgFe2O4 and CuFe2O4, respectively. These insights highlight the possibility of tuning the properties of ferrites using a cost-effective sol–gel method.

Identical Grain Atomic Force Microscopy Elucidates Facet‐dependent Restructuring of Copper for CO2 Electroreduction

Studies on the catalyst restructuring during the electrochemical CO2 reduction reaction (eCO2RR) are limited and mostly focused on Cu (001) or (111) single crystals as model systems. A comprehensive overview of the dynamic restructuring of the different Cu facets is lacking. Here, we first reveal the facet‐dependent restructuring of polycrystalline Cu electrodes through electron backscatter diffraction (EBSD) and identical grain atomic force microscopy (AFM). This combined analysis provides new insights into the evolution of crystal domains (EBSD) and surface topography (AFM) at varying conditions (e.g., applied potential and oxidative‐reductive pulses). The statistic slope distribution function was applied to study the restructuring asymmetry on five Cu facets (i.e., planar vs. atom stepped). We find that planar Cu (001) shows a square‐shaped morphology after eCO2RR with a 4‐fold asymmetry restructuring behavior, while triangular features dominate on Cu (111), evidenced by surface changes with 3‐fold asymmetry. 2‐fold restructuring is observed for Cu (114), (212), and (124) with atom steps, resulting in forming elongated structures. Therefore, the restructuring is dominated by the asymmetry of its facet lattice structure (i.e., planar vs. atom‐stepped). This work underscores the potential of combining techniques to elucidate the relationship between surface restructuring and crystal facets on different length scales.

Engineering flux-controlled flat bands and topological states in a Stagome lattice

Abstract We present the Stagome lattice, a variant of the Kagome lattice, where one can make any of the bands completely flat by tuning an externally controllable magnetic flux. This systematically allows the energy of the flat band to coincide with the Fermi level. We have analytically calculated the compact localized states associated to each of these flat bands appearing at different values of the magnetic flux. We also show that, this model features nontrivial topological properties with distinct integer values of the Chern numbers as a function of the magnetic flux. We argue that this mechanism for making any of the bands exactly flat could be of interest to address the flat-band superconductivity in such a system. Additionally, we show that our results are robust even in the presence of a small amount of disorder. Furthermore, we believe that the phenomenon of photonic flat band localization could be studied in the Stagome lattice structure, designed for instance using femtosecond laser induced single-mode waveguide arrays.

Study on the thermal control performance of lightweight minimal surface lattice structures for aerospace applications

With the rapid evolution of aerospace technology and the increasing complexity of space environments, the demand for lightweight, thermally insulated, and highly efficient heat dissipation materials in aircraft equipment has surged. This study addresses this critical need by investigating Triply Periodic Minimal Surface (TPMS) lattice structures, offering a novel design approach to enhance spacecraft thermal management under extreme temperatures. Our work introduces a methodology to quantitatively assess the thermal insulation and heat dissipation performance of various lightweight lattice sandwich structures. We constructed implicit function models of low volume fractions, including Gyroid, Diamond, Primitive, and IWP, and conducted experiments using an active cooling setup under controlled heating conditions at 300 °C. Key findings reveal that, at flow velocities ranging from 0.25 to 1.5 m/s, the Diamond model exhibited the highest convective heat transfer coefficient, surpassing the Gyroid, Primitive, and IWP models by 6.9 % to 427.3 %, 87.1 % to 485.6 %, and 1.5 % to 98.7 %, respectively. Conversely, at velocities between 1.5 and 3.75 m/s, the Gyroid model demonstrated superior heat exchange performance, improving by 14.6 % to 67.2 %, 73 % to 167.7 %, and 9 % to 64.8 % compared to the Diamond, Primitive, and IWP models. During thermal insulation tests at temperatures from 200 to 400 °C, the Diamond model showed the best insulation effect, while the Primitive model performed poorly. Based on the experimental data, we established empirical relationships between the Nusselt number, friction coefficient, and Geometric Surface Ratio (GS). These findings not only underscore the significant potential of TPMS lattice structures in aerospace applications but also provide a robust theoretical framework and practical guidelines for achieving efficient thermal management in lightweight aerospace manufacturing.

Formation of crystalline and quasicrystalline phases in as-cast and aged Al-Mg-Zn and Al-Mg-Zn-Ga alloys

Formation of crystalline and quasicrystalline phases in as-cast and aged Al-Mg-Zn and Al-Mg-Zn-Ga alloys

Development of hot melt extruded Polycaprolactone (PCL) matrices for an oral ultra-long-lasting delivery of Galantamine for Alzheimer’s disease therapy

Galantamine Hydrobromide (GAL) is a tertiary alkaloid, acting as a competitive and reversible cholinesterase inhibitor. It is indicated for the symptomatic treatment of patients from mild to moderate dementia level of the Alzheimer’s disease (AD) type. For treatment of mild to moderate AD, GAL is generally combined with other drugs. The purpose of this work was development and characterization of hot melt extruded (HME) matrices based on polycaprolactone (PCL) for GAL oral ultra-long-lasting delivery. PCL is biodegradable polymer, biocompatibility, water-insoluble and excellent for HME process. From HME drug and polymer mixtures arms from 1 % up to 50 wt-% of GAL were obtained. The raw materials and the as-obtained HME arms were characterized by particle size distribution (PSD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), wide angle x-ray scattering (WAXS) and dissolution test. Our findings showed that GAL possesses crystalline form I polymorphic, it is thermodynamically stable, and remains their particle and crystalline form even after HME process. Crystallization temperature of PCL increases with GAL content, indicating strong heterogeneous nucleating effect of drug on polymer crystallization process. SEM morphological analysis indicates continuous polymeric phase on surface. However, higher amounts of GAL (50/50 wt-%) presented clusters and heterogeneity, especially in extruded cross-section. It may have influenced the drug release property, decreasing the sustained release ability, due to the transport of medium molecules through the bulk extrudates by GAL soluble clusters. The diffractograms (WAXS) showed patterns peaks of GAL and PCL, indicating that GAL remains its crystalline structure and PCL recrystallized. In the dissolution test, PCL/GAL 80/20 and 90/10 achieved 100% with over seven days and profiles that can be tuned by varying GAL concentration. Finally, we demonstrate the feasibility of using HME process based on the mixture of PCL and GAL as proposals for oral therapies for conditions of AD. This is the first report showing PCL-GAL polymer matrices that achieves several-days drug release.

A new coamorphous ethionamide with enhanced solubility: Preparation, characterization, in silico pharmacokinetics, and controlled release by encapsulation.

This study reports the synthesis and the experimental-theoretical characterization of a new coamorphous system consisting of ethionamide (ETH) and mandelic acid (MND) as a coformer. The solid dispersion was synthesized using the slow solvent evaporation method in an ethanolic medium. The structural, vibrational, and thermal properties of the system were characterized. Density functional theory (DFT) calculations were performed to analyze the interactions between ETH and MND in the heterodimer. These results contributed to the suitable assignment of infrared (IR) vibrational modes, to determine the chemical reactivity descriptors and the electronic indices of each component of the molecule. Additionally, Hirshfeld surfaces analysis and calculations of absorption, distribution, metabolism, and excretion (ADME) parameters were performed to examine intermolecular interactions and predict the in silico pharmacokinetic profile of the ETH-MND compound and its forming molecules. Powder X-ray diffraction data confirmed the formation of a coamorphous binary system in the 1:2 and 1:3 ETH and MND ratios. Furthermore, the ETH-MND (1:3) solid dispersion remained amorphous for up to 150days when stored at 38°C and 75% relative humidity. DFT calculations, conducted both in vacuum and in ethanol, indicated that the formation of the coamorphous system is driven by hydrogen bonding between the NH2 groups of ETH and the C=O group of MND. Thermodynamic analysis showed that intermolecular interactions are favored in the gas phase, with Gibbs free energy of -3.20kcal/mol. The IR spectra showed a correlation between experimental and calculated data. Thermal analyses revealed glass transition temperatures of 59°C (1:2 ratio) and 61°C (1:3 ratio), indicating thermal stability of the coamorphous materials. Additionally, dissolution tests showed a 3.58-fold increase in the solubility of ETH compared to its crystalline form. The encapsulation of ETH-MND coamorphous systems in sodium alginate spheres via polyelectrolyte complexation was also investigated, demonstrating significant controlled drug release over 480min.

Experimental investigation on the mechanical properties of additively manufactured cobalt chrome (CoCr) lattice structures

Experimental investigation on the mechanical properties of additively manufactured cobalt chrome (CoCr) lattice structures

Thermomechanical behavior and microstructural evolution in nodes and struts of face-centered cubic lattice structures during laser powder bed fusion processing

Thermomechanical behavior and microstructural evolution in nodes and struts of face-centered cubic lattice structures during laser powder bed fusion processing

Chemical corrosion resistance mechanism of titanium alloy radiation rods with self-protected structure.

The chemical corrosion of the TC4 radiation rod surface (TRRS) during the ultrasonic casting process has the potential to significantly impair the smooth conduction of ultrasonic waves. However, in the later stages of corrosion, a self-protected structure (TSPS) emerges under the ultrasonic cavitation effect, which serves to impede the chemical corrosion of the TRRS and markedly reduce the rate of mass loss of the radiation rod. This ensures the smooth ultrasonic conduction of the radiation rod during operation. In this paper, an analysis of the microstructure of TSPS was conducted. The surface energy ratio at different crystal planes in TC4 and the self-diffusion coefficient for two phases of Ti in TC4 were calculated. The results indicated that TSPS is characterized by α-Ti grain basal planes concentrated parallel to the TRRS, higher α phase content, and fewer crystal defects. TSPS not only inhibits Ti dissolution and delays the onset of chemical corrosion, but also reduces the chemical corrosion rate.

Dual effect of Se(IV) and bentonite microbial community interactions on the corrosion of copper and Se speciation: Implication on repository safety assessment.

The Deep Geological Repository (DGR) design, the internationally safest option for the long-term disposal of high-level radioactive waste (HLW), features metal canisters encased in compacted bentonite clay and embedded deep within a host rock. Despite presenting a hostile environment for microorganisms, DGRs scenarios with favorable microbial-activity conditions must be considered for the safety assessment of this disposal. This study investigated the impact of Se(IV), as a natural analogue of 79Se present in the HLW, in anoxic microcosms of bentonite slurry spiked with a bacterial consortium and amended with lactate, acetate, and sulfate as electron donors/acceptor. The addition of the bacterial consortium promoted the rate of Se(IV) reduction to Se(0), while the tyndallization (heat-shock) of bentonite slowed this process. Se(IV) reduced the relative abundance of most genera of sulfate-reducing bacteria (SRB), while stimulating the abundance of Se-tolerant bacteria, which played an important role in Se(IV) reduction. Moreover, it was observed that lactate was the preferred electron donor, linking to the production and subsequent consumption of acetate. X-ray absorption spectroscopy (XAS) and high-resolution transmission electron microscopy (HRTEM) revealed the reduction of Se(IV) forming amorphous Se(0) nanospheres. In addition, HRTEM showed that the biogenic Se(0) undergo a biotransformation to more stable crystalline forms, contributing to the immobilization of Se in the case of HLW release. Additionally, the sulfide generated by the activity of SRB reacted with Cu producing corrosion products (CuxS) on the surface of the copper material.

Two-scale concurrent topology optimization of lattice structures with multiple microstructures subjected to dynamic load

Two-scale concurrent topology optimization of lattice structures with multiple microstructures subjected to dynamic load

Synergizing machine learning and multiscale shakedown method for shakedown loading capacity evaluation of parameterized lattice structures

Synergizing machine learning and multiscale shakedown method for shakedown loading capacity evaluation of parameterized lattice structures