X-ray Diffraction Characterization Research Articles

Temperature dependence mechanism of high-temperature oxidation of transition metal silicide MoSi2

Transition metal silicides represented by MoSi2 have excellent oxidation resistance and are widely used as high-temperature anti-oxidation coatings in hot end components of power equipment. However, the mechanism of temperature-dependent growth of MoSi2 oxidation products has not been revealed. Therefore, this study investigated the formation characteristics of oxide film and silicide-poor compound on MoSi2 at temperatures of 1000 °C–1550 °C through high-temperature oxidation experiments, combined with microscopic Raman spectroscopy, scanning electron microscope, and x-ray diffraction (XRD) characterizations. The result showed that MoSi2 underwent high-temperature selective oxidation reactions at 1000 °C–1200 °C, forming MoO2 and SiO2 oxide film on the substrate. As the oxidation temperature increased to 1550 °C, after 100 h of oxidation, along with the disappearance of MoO2 and the phase transformation of SiO2, a continuous Mo5Si3 layer with a thickness of approximately 47 μm was formed at the SiO2–MoSi2 interface. Thermodynamics and kinetic calculations further revealed the mechanism of temperature-dependent growth of oxidation products (MoO2 and Mo5Si3) during high-temperature oxidation process of MoSi2. As the temperature increased, the diffusion flux ratio of O and Si decreased, leading to a decrease in oxygen concentration at the interface and promoting the growth of the Mo5Si3 layer. Its thickness is an important indicator for evaluating the oxidation resistance of MoSi2 coatings during service. This study provides experimental and mechanistic insights into the temperature-dependent growth behavior of Mo5Si3 during the high-temperature oxidation of MoSi2 coating, and provides guidance for predicting the service life and improving the oxidation resistance of silicide coatings.

Research on the epitaxial direction control and mechanism of polycrystalline diamond grains

The control of diamond film growth is crucial for the application of diamond films. In this article, different diamond film samples were prepared by adding nitrogen and oxygen in different proportions during the growth process. The key conditions for controlling the growth of diamond film with preferred orientation were obtained using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy characterizations. During the growth process, the growth of the diamond film with (100) preferred orientation could be achieved by adjusting nitrogen content. It was necessary to introduce nitrogen and oxygen in the growth process, and precisely regulate the ratio of the two to obtain the (111) preferred orientation of the diamond film. When only oxygen was introduced during growth, the preferred orientation of the diamond could not be achieved, leading to a smaller grain size and poorer crystal quality. From the perspective of grain morphology to film morphology evolution, this study obtained the crystal orientation control conditions during the diamond film growth, which has important guiding significance for the application of the diamond film. This study seeks to drive progress in the large-scale growth of readily machinable diamond and the evolution of diamond-grain optical fiber sensing through comprehensive investigations into the correlation between the preferred orientation in polycrystalline diamonds and reaction conditions.

The activation of PMS for PFOA degradation by adjustable metal stripping Fe/Co/N@BC catalysts: Degradation performance with single-line oxygen and high-valent metal oxides as the main active substances

In this study, a modified biochar (P-Fe/Co/N@BC) catalyst was prepared with wood chips as raw material by hydrothermal method for the activation of peroxymonosulfate (PMS) and degradation of perfluorooctanoic acid (PFOA). Scanning electron microscopy (SEM), x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) characterization methods were used to demonstrate the presence of FeNx, CoNx, Fe-Co and CO active sites, which contribute to the improvement of the PMS activation capacity for single-line oxygen (1O2). Electron paramagnetic resonance spectroscopy (EPR), reactive oxygen species (ROS) scavenging experiments and methyl phenyl sulfoxide (PMSO) conversion experiments were performed to clarify the main mechanisms of PFOA degradation by reactive species. Further, 1O2, sulfate radical (SO4−), hydroxyl radical (OH), high-valent metal oxides (Fe(IV) and Co(IV)) were jointly involved in the degradation of PFOA, and nonradical were the main activation pathway of PMS. In particular, Fe3+ decomposed from Fe(IV) in the presence of Fe0 and Co2+ decomposed from Co(IV) are able to enhance iron cycling and cobalt cycling, respectively. Meanwhile, Co0 accelerates the conversion of Co3+ to Co2+. The findings suggested that the removal rate of the P-Fe/Co/N@BC-PMS system (99 %) was much higher than that of the P-Fe-N-C/PMS (68.9 %) over 180 min. It emphasized that the incorporation of PTFE (polytetrafluoroethylene) can regulate metal leaching significantly and improve the cycling stability of the catalysts. This study aimed to prepare efficient and stable modified biochar catalysts to activate PMS, which provided an effective solution to the problem of metal ion leaching from metal-modified biochar materials.

Constructing Cu9S5@CuSe heterostructures under microwave irradiation for rechargeable magnesium batteries

Copper chalcogenides are believed as the prospective cathode materials for rechargeable magnesium batteries. However, their practical application is seriously restricted by slow diffusion and reaction kinetics due to the large charge/radius ratio of divalent Mg2+ ions. Herein, a simple two-step microwave-assisted synthesis method is rationally developed to construct Cu9S5@CuSe heterostructures as the capable cathode materials for rechargeable magnesium batteries. Two-dimensional CuSe nanosheets are vertically grown on the surface of single-crystal Cu9S5 substrate through selenation reaction under microwave irradiation to form the mixed-dimensional heterostructures. Electrochemical measurements reveal that the as-synthesized Cu9S5@CuSe heterostructures show high reversible capacity of 240 mAh/g and good long-term cyclic stability with approximate 0.013 % capacity decay per cycle at 500 mA g−1 within 1000 cycles. Furthermore, the obviously enhanced rate capability can be achieved in comparison with that of single-crystal Cu9S5 substrate and CuSe nanoparticles. Ex-situ X-ray photoelectron spectroscopy and X-ray diffraction characterizations reveal favourable electrochemical conversion reaction over the Cu9S5@CuSe heterostructure cathode. The superior electrochemical properties are attributed to the optimized diffusion kinetics within the unique heterostructure. This research offers a valuable strategy to develop high-performance cathode materials with favourable kinetics for magnesium batteries.

Facile Synthesis of Fe-Doped, Algae Residue-Derived Carbon Aerogels for Electrochemical Dopamine Biosensors.

An abnormal level of dopamine (DA), a kind of neurotransmitter, correlates with a series of diseases, including Parkinson's disease, Willis-Ekbom disease, attention deficit hyperactivity disorder, and schizophrenia. Hence, it is imperative to achieve a precise, rapid detection method in clinical medicine. In this study, we synthesized nanocomposite carbon aerogels (CAs) doped with iron and iron carbide, based on algae residue-derived biomass materials, using Fe(NO3)3 as the iron source. The modified glassy carbon electrode (GCE) for DA detection, denoted as CAs-Fe/GCE, was prepared through surface modification with this composite material. X-ray photoelectron spectroscopy and X-ray diffraction characterization confirmed the successful doping of iron into the as-prepared CAs. Additionally, the electrochemical behavior of DA on the modified electrode surface was investigated and the results demonstrate that the addition of the CAs-Fe promoted the electron transfer rate, thereby enhancing their sensing performance. The fabricated electrochemical DA biosensor exhibits an accurate detection of DA in the concentration within the range of 0.01~200 µM, with a detection limit of 0.0033 µM. Furthermore, the proposed biosensor is validated in real samples, showing its high applicability for the detection of DA in beverages.

Anomalous magnetization induced by local chemistry fluctuations in Mn-containing α’-martensite

An anomalous increase in magnetization was investigated in a cold-rolled high-Mn TRIP steel (16.8 wt% Mn) annealed at 350°C for times varying from 5 to 120 min, before the start of austenite reversion (α’ → γ). Besides in-situ and ex-situ magnetic measurements, the full characterization of this phenomenon was also performed with the aid of X-ray diffraction (XRD), Mössbauer spectroscopy, and microstructural characterization using electron backscatter diffraction (EBSD) and atom probe tomography (APT). Based on XRD measurements, the volume fraction of austenite and α’-martensite was estimated as a function of annealing time, as well as their lattice strain. Phase quantification confirmed the absence of newly-fresh α’-martensite in the material during annealing at 350°C. Short annealing up to 15 min promoted the increase of Ms (saturation magnetization) due to stress relief in α’-martensite (Villari effect). Further annealing to 30 min promotes the decrease in Ms driven by short-range solute reorganization within the lattice. After 60 min annealing, the creation of long-range solute-depleted zones (i.e. confined zones highly enriched in Fe) causes a new increase in Ms. In comparison, for 120 min of annealing time, Ms tends to remain unaltered. These findings revealed that short- and long-range chemical fluctuations strongly affect the saturation magnetization of the steel and brought new insights on the use of magnetic probing as a tool for phase quantification in Mn-bearing steels.

Large area MoSe2 and MoSe2/Bi2Se3 films on sapphire (0001) for near-infrared photodetection

The fabrication of heterojunction-based photodetectors (PDs) is well known for the enhancement of PDs performances, tunable nature of photoconductivity, and broadband application. Herein, the PDs based on MoSe2 and MoSe2/Bi2Se3 heterojunction on sapphire (0001) substrates were deposited using a r.f. magnetron sputtering system. The high-resolution x-ray diffraction and Raman spectroscopy characterizations disclosed the growth of the 2-H phase of MoSe2 and the rhombohedral phase of Bi2Se3 thin films on sapphire (0001). The chemical and electronic states of deposited films were studied using x-ray photoelectron spectroscopy and revealed the stoichiometry growth of MoSe2. We have fabricated metal-semiconductor–metal type PD devices on MoSe2 and MoSe2/Bi2Se3 heterojunction and the photo-response measurements were performed at external voltages of 0.1–5 V under near-infrared (1064 nm) light illumination. The bare MoSe2 PD device shows positive photoconductivity behavior whereas MoSe2/Bi2Se3 heterojunction PD exhibits negative photoconductivity. It was found that the responsivity of MoSe2 and MoSe2/Bi2Se3 heterojunction PDs is ~ 1.39 A W−1 and ~ 5.7 A W−1, respectively. The enhancement of photoresponse of MoSe2/Bi2Se3 PD nearly four-fold compared to bare MoSe2 PD shows the importance of heterojunction structures for futuristics optoelectronic applications.

Regulating the redox and non-redox enzyme-mimicking activities of Ce-UiO-66-NO2 nanozyme for dual-mode sensing of phosphate

Nanozymes with multi-enzyme mimicking activities have received a great deal of attention, which can mimic peroxidase, oxidase, superoxide dismutase, catalase, and alkaline phosphatase, etc. However, the current research focuses on regulating the multi-enzyme-like activity of redox types. Regulating the catalytic activity of different types of nanozyme such as redox and non-redox types is still full of challenges. Here, Ce-UiO-66-NO2 with hydrolase-like activity and oxidase-like activity was taken as the model to regulate its dual enzyme-like activities. Interestingly, a distinct response in oxidase-like and hydrolase-like activities of Ce-UiO-66-NO2 was observed towards the addition of phosphate (PO43-). When PO43- was present, the oxidase mimicking activity of Ce-UiO-66-NO2 was enhanced and the hydrolase mimicking activity was inhibited. With X-ray photoelectron spectroscopy, Fourier transform infrared spectrometry, X-ray diffraction and zeta potential characterizations, the regulatory mechanism was recognized as the coordinated impact of the reactive oxygen species, electrostatic adsorption and competitive inhibition. As a proof of concept, a colorimetric/fluorometric dual-mode sensing method for detecting PO43- through regulating the dual enzyme mimicking activities of Ce-UiO-66-NO2 was constructed. PO43- can be quantitated with 3,3′,5,5′-tetramethylbenzidine (TMB) and 4-methylumbelliferyl phosphate (4-MUP) as substrates for colorimetric and fluorescent sensing, respectively. This study will deepen the understanding of nanozymes with multi-enzyme mimicking activities and accelerate the development of efficient sensing.

Influence of Film Thickness on Nanofabrication of Graphene Oxide

Nanofabrication of two-dimensional materials through mechanical machining is normally influenced by not only process parameters such as load and velocity but also intrinsic properties such as strength and thickness. Herein, we examined the effects of graphene oxide (GO) film thickness on nanofabrication on the plane surfaces and at the step edges using scanning probe microscope lithography. The material removal of GO initiates at the load above a critical value, which strongly depends on film thickness and locations. With the increase in film thickness, the critical load decreases monotonically on the plane surfaces but increases gradually at the step edges. Further, the critical load for the GO monolayer at the step edges is at least 25 times lower than that on the plane surfaces, and the gap decreases to around 3 times when GO thickness increases to four layers. Then, mechanical nanofabrication initiating from the GO step edge allows producing various nanopatterns under extremely low loads around 1 nN. Finally, the GO nanostructures are deoxidized by annealing at 800 °C in high-purity argon to restore their highly functionalized conjugated structures, which are supported by X-ray diffraction and Raman characterizations. This work provides a novel approach to fabricating graphene-like nanostructures by deoxidizing GO after nanofabrication, which holds significant potential for applications in graphene-based devices.Graphical

Optimizing the fluoride removal from drinking water through adsorption with mesoporous magnetic calcite nanocomposites

Fluoride (F−) contamination in groundwater is a global concern arising from natural processes and human activities. This study investigates the adsorption of F− using surface-activated magnetic calcite nanocomposites (NCs) synthesized via co-precipitation assisted wet-impregnation (CP-WI). Various Fe3O4 loadings and calcination temperatures (300 °C and 500 °C) were explored to optimize synthesis parameters. Batch adsorption experiments were conducted to assess the performance of synthesized nanoparticles (NPs) and nanocomposites (NCs). BET, FTIR spectroscopy, X-ray diffraction, and SEM characterization techniques were employed to analyze the physicochemical properties, including surface functional groups, crystallite size, and morphology. The adsorption process was investigated using RSM statistical design with adsorbent dose (A) and F− concentration (B) as independent variables. 0.5Fe-C-NC-5, calcined at 500 °C, exhibited superior adsorption capacity (7.81 mg/g) compared to Fe3O4 and calcite NPs (6.57 mg/g and 6.81 mg/g, respectively). Maximum F− adsorption occurred within 10 min of contact time. NPs and NCs that were exposed to higher calcination temperatures, reaching up to 500 °C, showed an increase in crystallite development while experiencing a reduction in surface area and an enlargement of pore size compared to those treated at lower temperatures. The BET analysis revealed a narrow, slit-like mix of microporous and mesoporous surface with a type IV isotherm and H3 hysteresis loop, indicating multilayer adsorption followed by capillary condensation. The SEM images displayed columnar shapes of CaCO3 polymorph in the prepared Fe3O4-calcite NP and Fe–C NP, which can be attributed to lower calcination or synthesis temperatures.

Synthesis of Zn/SBA-15 from Rice Husk Ash Using Sonochemical Methods as a Quercetin Drug Delivery Matrix

Quercetin is a drug candidate with bioavailability but currently limited, necessitating the use of a delivery matrix, such as Santa Barbara Amorphous-15 (SBA-15). Rice husk ash, containing a significant amount of silica, served as a precursor in the synthesis of SBA-15, which can be functionalized with nanoparticles, including zinc, using sonochemical methods. Therefore, this study aimed to synthesize Zn/SBA-15 using sonochemistry and evaluate the potential as a drug delivery matrix for quercetin. SBA-15 was formed by sonication of a sodium silicate from rice husk and pore director Pluronic P-123, followed by impregnating Zn at 2%, 4%, and 6% w/w. The characterization of X-ray diffraction (XRD) and fluorescence (XRF) showed a broad peak at 2theta 18-30◦ with Zn levels of 1.89%, 3.69%, and 5.06%. Furthermore, the analysis of transmission electron microscopy (TEM) showed the presence of Zn nanoparticles with a range size of 4-14 nm. In vitro drug delivery experiments were carried out using Zn/SBA-15 at concentrations of 1:1 and 1:2 to quercetin. The in vitro test results for a drug loading of quercetin with Zn/SBA-15 6% 1:1 was 28.30 mg/g. The encapsulation efficiency was 10.96% and the drug release reached 33.64% after 240 minutes.

Study on Crystal Structure, Surface Area, and Energy Gap Behaviors of Nanotitania Polymorphs Prepared Using Monoethanolamine

Polymorphous nanotitania samples were prepared from titanium butoxide (TTB) as a precursor using sol-gel processing in ethanol as a solvent, without and with monoethanolamine (MEA). The experiments used 5.25 mL TTB and MEA with varied volumes of 0.5, 1.0, 1.5, and 2.0 mL. The sample without MEA was specified as sample A, and the samples produced using MEA were specified as samples B, C, D, and E, respectively. All samples were calcined at 500 °C for 4 h and then collected data by X-ray Diffraction (XRD), the Brunauer-Emmett-Teller (BET) method used to analyze Surface Area Analyzer (SAA), Transmission Electron Microscopy (TEM), Raman Spectroscopy, and UV-Visible Diffuse Reflectance Spectroscopy (UV-Vis DRS). The results of XRD characterization indicate that samples A and B form anatase phase, while samples C and D are composed of anatase, brookite, and rutile phases, and sample E is consisted of anatase and brookite phases with weight percentages of (94.53 ± 1.72) % and (5.47 ± 0.36) %, respectively. The presence of the three phases of titania is also confirmed by Raman spectroscopy analysis, which showed anatase peaks at 146, 197, 398, and 513 cm-1, brookite peaks at 245 and 402 cm-1, and rutile peaks at 319, 436, and 612 cm-1. According to XRD, the samples have the particle size in the range of 14-19 nm. A representative sample (sample C) was also characterized using TEM, revealing a particle size of 16.0 ± 0.3 nm. This representative sample revealed the largest surface area of 172.2 m2/g, as seen by BET, and the lowest energy gap of 3.03 eV.

Synthesis and study of optical properties of a Gd3+-doped NaYF4 phosphor for phototherapy lamp application.

In recent trends, radiation falls under the narrowband ultraviolet-B region (305-315 nm) widely used in phototherapy lamp applications in the treatment of skin diseases. In this paper, we report a Gd3+-doped NaYF4 luminescent material synthesized for the first time using the low-temperature co-precipitation method. It crystallized into a face-centred cubic structure, as confirmed by X-ray diffraction characterization techniques and Rietveld refinement. The photoluminescence property of the as-prepared sample shows a highly intense, sharp emission band obtained at 311 nm, which belongs to the narrowband ultraviolet-B region and corresponds to the transition of the 6P7/2→8S7/2 level of the Gd3+ ions under 272 nm excitation (8S7/2 to 6IJ). The transitions of the Gd3+ ions are detected entirely with different concentrations of Gd3+ ions. Scanning electron microscopy analysis indicated that the average particle was 288 nm. The critical distance for energy transfer was calculated to be equal to 11.5017 Å. Dipole-dipole interaction is responsible for energy transfer, as analyzed by Dexter theory. These excellent optical characteristics, together with their highly efficient and low-cost synthesis approach, indicate that synthesized NaYF4:Gd3+ phosphors have excessive potential for phototherapeutic lamp applications.

Synthesis of millimetre-scale HZSM-5 single crystals by secondary hydrothermal treatment

Millimetre-scale HZSM-5 single crystals were successfully synthesized by a two-step hydrothermal method. In the first step, millimetre-sized silicalite-1 single crystals were prepared by hydrothermal synthesis using quartz tube as siliceous source. In the second step, framework Al atoms were inserted into the single crystals of silicalite-1 by another hydrothermal treatment involving NaAlO2 as aluminium source. Through the characterizations of power and single crystal X-ray diffraction, optical microscope, ICP, 27Al MAS NMR, 29Si MAS NMR, and n-propylamine temperature-programmed decomposition (NPA-TPD), it was confirmed framework Al atoms with uniform spatial distribution can be inserted into giant single crystals of silicalite-1 with no obvious effects on the crystal structure, size and morphology. Such giant HZSM-5 single crystals are a promise candidate for the probe adsorption investigations, which can be applied in the measurement of framework Al spatial distribution. The strategy of insertion of aluminium or other heteroatoms of pure siliceous zeolite through secondary hydrothermal method provides a possible route to prepare giant single crystals that is difficult to synthesize directly.

A high-sensitive anisotropic magnetoresistive sensor based on hybrid Ta/NiFe/Ta/Al multilayer structure

High sensitivity is crucial for anisotropic magnetoresistive (AMR) sensors in industrial applications. In this paper, a high- sensitive AMR sensor based on magnetoresistive thin films with Ta/NiFe/Ta/Al four-layer structure is proposed and fabricated. Firstly, the structural parameters were optimized by finite element analysis. Secondly, thin film samples and AMR sensors were prepared. Through the analysis and characterization of reluctance change rate, hysteresis loop, x-ray diffraction and surface morphology and structure, the process parameters were optimized. Finally, the sensor was connected to the designed external circuit, and its technical parameters were tested in a magnetic field test system. The results show that the prepared AMR sensor performs well. It has a high sensitivity of 1.27 mV/V/Oe, a low bridge offset voltage of ±1.64 mV V−1, and a low temperature coefficient of sensitivity of −0.102%/°C. The results contribute to the future development of AMR magnetic field sensor chips.

Temperature dependent dielectric studies of pure and Sr doped Pr2NiMnO6

The physical properties of Sr doped Pr2NiMnO6 have been discussed. The Samples of Pr2-xSrxNiMnO6 (x = 0.0, 0.2, 0.4) have been synthesized via Solid State Reaction. The X-Ray diffraction and Scanning Electron Microscopy characterizations were applied to examine the structure and surface morphology. Observed XRD patterns reveal the structure to be monoclinic with P21/n space group. Increase in the Sr doping resulted in the reduction in the particle size and crystallite size. Raman peak corresponding to the wave number 515 cm−1 represents the asymmetric mode and the other one at 655 cm−1 represents symmetric mode of the NiO6/MnO6 octahedra. The frequency and temperature dependent dielectric studies on samples of Pr2-xSrxNiMnO6 (x = 0.0, 0.2, 0.4) suggest the decrease in dielectric constant with the increase in Sr doping. The appearance of relaxation peak has been also observed in the temperature dependent dielectric loss plots. Furthermore, the ac conductivity reduction has been seen with the increase in Sr doping.

Single Crystal Growth and X-ray Diffraction Characterization of a Quasi-Spin Chain Compound, Li2CuO2

We report the growth of single crystals and X-ray diffraction characterization of the quasi-one-dimensional spin chain compound, Li2CuO2. The single crystals were grown using the high-temperature solution growth technique. The resulting blade-shaped crystals exhibit a shiny black color, with dimensions reaching several millimeters along the crystallographic b-axis. The as-grown crystals were characterized using powder X-ray diffraction and Laue back reflection. The I-centered orthorhombic, Immm, structure was confirmed. Crystal structure parameters were determined to be a = 3.6744 Å, b = 2.8600 Å, and c = 9.4257 Å from Rietveld analysis. Our work helps to remove obstacles to the synthesis and study of a model cuprate system, Li2CuO2, facilitating the use of experimental probes that require sizable crystals.

Molecular dynamics to model carbon infiltration into a porous silicon matrix: An experimental and computational approach

In this work, a porous silicon matrix (PSm) and its functionalization with carbon atoms are modeled by molecular dynamics (MD); the simulation is correlated experimentally to analyze the model results. Computationally, the Tersoff potential for the silicon carbon system is used to build a model by MD using Large-scale Atomic/Molecular Massively Parallel Simulator free-source code (LAMMPS). First, a model of a PSm with an aleatory distributed macroporous was built; then, C atoms were injected into the PSm model to functionalize the matrix; finally, the model shows the functionalization of the PSm, forming carbon-silicon composites, which are Si clusters surrounded by C atoms. Experimentally, PSm was fabricated using samples of a p-type crystalline silicon wafer by electrochemical etching. A colloidal suspension of graphene oxide (GOs) was used as a source of carbon atoms: the GOs was added to the electrolyte, during the etching process, to functionalize the PSm with C atoms. AFM images show that the PSm pores are not obstructed after functionalization. Carbon-silicon composites were formed into the PSm samples according to X-ray diffraction and EDS characterizations. The results of the modeling agree with the results of the experiments.

Microstructural origin of high strength and high strain hardening capability of a laser powder bed fused AlSi10Mg alloy

Compared to a cast AlSi10Mg alloy, a laser powder bed fused (LPBF) AlSi10Mg alloy shows superior yield strength and strain hardening capability. However, the underlying microstructure origin has not been comprehensively understood. In this work, the microstructural evolution of an LPBF AlSi10Mg alloy during tensile deformation was investigated. Synchrotron X-ray diffraction characterization shows that both stress and strain exhibit significant partition between an Al phase and a Si phase upon tensile deformation. This leads to a significant strain gradient between those two phases, which is evident by the high density of dislocations in the cell boundaries of the deformed alloy. The strain gradient results in long-range internal stress, also known as back stress, in the cell boundaries, and in turn leads to enhanced strength and strain hardening in the LPBF AlSi10Mg alloy. Quantitatively analyses via loading-unloading-reloading tests show that during the tensile deformation, the back stress contributes 135 MPa to the yield strength of the alloy, which continuously increases with increasing the strain beyond the yielding point. This work illuminates the microstructural origin of the back stress in the LPBF AlSi10Mg alloy, i.e. the back stress arises from the stress/strain partition between the Al and Si phases in the cellular structures, and the back stress leads to significant strengthening of the alloy upon tensile deformation. This work may also provide guidance for manipulating the mechanical properties of additively manufactured Al-Si alloys for specific application needs.

Interfacial "Double-Terminal Binding Sites" Catalysts Synergistically Boosting the Electrocatalytic Li2S Redox for Durable Lithium-Sulfur Batteries.

Catalytic conversion of polysulfides emerges as a promising approach to improve the kinetics and mitigate polysulfide shuttling in lithium-sulfur (Li-S) batteries, especially under conditions of high sulfur loading and lean electrolyte. Herein, we present a separator architecture that incorporates double-terminal binding (DTB) sites within a nitrogen-doped carbon framework, consisting of polar Co0.85Se and Co clusters (Co/Co0.85Se@NC), to enhance the durability of Li-S batteries. The uniformly dispersed clusters of polar Co0.85Se and Co offer abundant active sites for lithium polysulfides (LiPSs), enabling efficient LiPS conversion while also serving as anchors through a combination of chemical interactions. Density functional theory calculations, along with in situ Raman and X-ray diffraction characterizations, reveal that the DTB effect strengthens the binding energy to polysulfides and lowers the energy barriers of polysulfide redox reactions. Li-S batteries utilizing the Co/Co0.85Se@NC-modified separator demonstrate exceptional cycling stability (0.042% per cycle over 1000 cycles at 2 C) and rate capability (849 mAh g-1 at 3 C), as well as deliver an impressive areal capacity of 10.0 mAh cm-2 even in challenging conditions with a high sulfur loading (10.7 mg cm-2) and lean electrolyte environments (5.8 μL mg-1). The DTB site strategy offers valuable insights into the development of high-performance Li-S batteries.