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Mg alloys are considered the most promising engineering materials because of their unique properties. However, the uncontrolled corrosion rate of these alloys limits their applications. Therefore, in this study, a micro-arc oxidation layer was used as a transition layer to “directly” grow a zinc-based metal-organic framework (MOF) composite coating on the surface of a Mg alloy (AZ91D). Herein, the two zeolitic imidazolate framework (ZIF-8) coatings with different morphologies were separately prepared by homologous metal oxide induction and a one-step in-situ growth method. The superhydrophobic composite coating showed strong hydrophobicity and self-cleaning properties, which could prevent the penetration of water and corrosive ions (Cl−) into the surface of AZ91D. Electrochemical tests demonstrated that the super-hydrophobic composite coatings greatly enhanced the corrosion resistance of AZ91D, and the corrosion current density decreased from 10−5 to 10−9 A/cm2. These results indicate that the ZIF-8 coatings are beneficial for improving the hydrophobicity and enhancing the corrosion resistance of Mg alloys. Therefore, MOF composite coatings provide a new strategy that can be used to prepare multifunctional anticorrosion coatings on metal substrates.

Biodegradable magnesium (Mg) and its alloy show huge potential as temporary bone substitute due to the favorable biocompatibility and mechanical compatibility. However, one issue deserves attention is the too fast degradation. In this work, mesoporous bioglass (MBG) with high pore volume (0.59 cc/g) and huge specific surface area (110.78 m2/g) was synthesized using improved sol-gel method, and introduced into Mg-based composite via laser additive manufacturing. Immersion tests showed that the incorporated MBG served as powerful adsorption sites, which promoted the in-situ deposition of apatite by successively adsorbing Ca2+ and HPO42−. Such dense apatite film acted as an efficient protection layer and enhanced the corrosion resistance of Mg matrix, which was proved by the electrochemical impedance spectroscopy measurements. Thereby, Mg based composite showed a significantly decreased degradation rate of 0.31 mm/year. Furthermore, MBG also improved the mechanical properties as well as cell behavior. This work highlighted the advantages of MBG in the fabrication of Mg-based implant with enhanced overall performance for orthopedic application.

Statement of problem When 3-dimensional printing casts, the operator can change the type of resin and the printing layer thickness, reducing the fabrication time. However, how these parameters affect the accuracy of 3-dimensionally printed casts is unknown. Purpose The purpose of this in vitro study was to evaluate the accuracy of 3-dimensionally printed casts by using a stereolithography (SLA) 3-dimensional printer (Forms2) with 3 different layer thickness (25, 50, and 100 μm) and 2 different resins (Gray and Cast) and by comparing the time to obtain each cast. Material and Methods One master cast was scanned, and a single file was printed several times. The printed casts were then scanned by using a laboratory scanner. The standard tessellation language (STL) files provided by the laboratory scanner were superimposed and compared by using a software program (Geomagic Control; 3D Systems). The 2-way ANOVA test was used for the trueness evaluation, followed by the Tukey test to identify differences among the groups (α=.05). Results No statistically significant differences in accuracy were found among the 3 different layers for either resin (P>.05). Printing time doubled as layer thickness decreased. Conclusions This study showed that when printing casts, the fastest printing settings can be used without losing accuracy and that the laboratory digital workflow can be accelerated with selection of the resin and cast layer, as the type of resin and layer thickness did not influence the quality of the casts.

Additive manufacturing (AM) of Mg alloys has become a promising strategy for producing complex structures, but the corrosion performance of AM Mg components remains unexploited. In this study, wire and arc additive manufacturing (WAAM) was employed to produce single AZ31 layer. The results revealed that the WAAM AZ31 was characterized by significant grain refinement with non-textured crystallographic orientation, similar phase composition and stabilized corrosion performance comparing to the cast AZ31. These varied corrosion behaviors were principally ascribed to the size of grain, where cast AZ31 and WAAM AZ31 were featured by micro galvanic corrosion and intergranular corrosion, respectively.

In this work comparative analysis of the effect of various active materials and use of photonic crystal in active layer of organic photodetector in the wavelength range between 400 nm and 700 nm is described. The active organic material used in the photodetector is PH3T: PCBM. The various materials used for the analysis of absorbance and transmittance between the active layer are nc_ZnO organic material and Al2O3, GaAs and silicon nitride (Si3N4) semiconductor materials. The maximum absorbance reported in this work are 80.0969%, 80.0451%, 75.4784%, 80.8878%, 76.8223% for without PC on nc_ZnO organic layer, with nc_ZnO PC on nc_ZnO layer, Al2O3, GaAs and silicon nitride (Si3N4) semiconductor materials with PC. The absorption is almost flat between 70% and 80% for without PC and for with PC having materials nc_ZnO, Al2O3 and GaAs between the wavelength range 450 nm to 630 nm. We have achieved an improvement in the absorption at wavelength ranging from 630 nm to 700 nm by using PC with nc_ZnO organic material.

Semiconductor Quantum Dots have unique properties, such as the quantum size effect that provide the breakthrough in optoelectronic devices. The small effective mass of electron and hole open-up an avenue of wide bandgap tunability in InAs Quantum Dots (QDs), making them an attractive material for solar cell application. Therein, 4x4 Luttinger Kohn Hamiltonian method is used to calculate the absorption co-efficient of epitaxially grown InAs QDs. Further, we studied the size-dependent absorption co-efficient and the barrier material model of InAs QDs capping with InP and GaAs. Our theoretical simulation predicts the efficiency of InAs/GaAs and InAs/InP system in the intrinsic layer of p-i-n structure solar cells.

In this work, a novel bamboo-like carbon nanotubes@Sn4P3@carbon (BLCNTs@Sn4P3@C) coaxial nanotubes are designed and prepared using a newly developed hydrothermal method followed by a phophidation process. The prepared Sn4P3 nanoparticles are uniformly coated and wrapped on the one-dimensional (1D) bamboo-like CNTs, which is covered by a uniform carbon layer to form a sandwich-like structure with Sn4P3 in between. The inner CNT and outer carbon can effectively maintain the structural stability and serve as the good electron conductors. Additionally, the outer carbon coating layer can effectively keep BLCNTs@Sn4P3@C nanotubes separate each other, preventing aggregation of Sn4P3 during charge/discharge when this material is used as anode for sodium ion batteries. The anode of BLCNTs@Sn4P3@C shows excellent reversible capacity and a long cycling of over 2000 cycles. The unique design of coaxial nanotubes is greatly beneficial to the electrochemical performance of Sn4P3 for sodium ion storage.

The aim of this study was to investigate the engineering characteristics of different mixes of copper slag and fly ash stabilised with lime or cement for use as a base layer of flexible highway pavements. The effects of fly ash content, binder content, curing period and wetting–drying cycles on unconfined compressive strength (UCS), indirect tensile strength (ITS), resilient modulus and permanent strain were studied. The ITS was found to be 17 and 18% of the UCS for a mixture of lime and cement, respectively. Mixes with 6% lime or cement content, which were found to satisfy both the strength and durability criteria suggested by the Indian Road Congress, are therefore recommended for use in the base layer of flexible road pavements. The fitting of different existing models for predicting resilient modulus and permanent strain was compared and constants of the best-fitting model are presented. On the basis of a finite-element analysis of a five-layer flexible pavement system, pavements with mixes of copper slag, fly ash and lime or cement in the base layer were found to have up to 78 and 55%, respectively, higher service life compared with pavements with wet-mix macadam as the base material.

The present work illustrates a novel approach for the maskless and resistless fabrication of nanopatterned metal layers on Si substrates, based on the combination of nanomechanical surface modification techniques (such as nanoindentation and nanoscratching) and electrodeposition. Single crystal (1 0 0) n -doped Si substrates were first cleaned from native oxide. Nanoindentation and nanoscratching were then used to locally change the substrate microstructure and create regions with reduced electrical conductivity. The substrates were finally mounted as cathode electrodes in a three-electrode electrochemical cell to potentiostatically deposit a Ni layer. Electrodeposition was prevented in regions with modified microstructure, enabling the formation of a patterned Ni layer. The fabrication of several patterns including continuous Ni lines of 200 nm width and several microns length was obtained.

We investigated the growth and electronic properties of Co-phthalocyanine (CoPc) molecule deposited on iron film with different structures (pseudomorph-fcc and bcc) and on iron nanowires by scanning tunnelling microscopy and X-ray absorption spectroscopy (XAS). CoPc molecules self-assemble in a two-dimensional (2D) arrangement with the molecular plane parallel to the iron surfaces, and the local order is lost after the first layer. The molecule ferromagnet interaction causes the broadening of Co and N unoccupied molecular states as well as different electronic distribution of N states as a function of the atomic structure of iron surface. The ferromagnetic coupling between the molecule and the iron film is dominated by the electronic interaction between Co and the first Fe layer. CoPc 2D arrangement turns into 1D by using as a template the iron nanowire grown on a facet surface of oxidized Cu(332) surface. CoPc molecules interact weakly with the iron nanowires manifesting a substantial Co 3d(z) spectral feature in XAS spectrum and the possibility of a magnetic interaction between Co moment and iron nanowires. Both CoPc 2D and 1D arrangements can open up new interesting scenarios to tune the magnetic properties of hybrid interfaces involving metallorganic molecules.

Poly(arylene sulfide sulfone)/graphene nanoplate (PASS/GNP) composites with segregated structure based on continuous polymer fiber skeletons were fabricated by coating a thin conductive layer on the PASS fibers and then performing compression molding. The formation of a unique segregated conductive network endowed the PASS/GNP composites with high electrical conductivity and excellent electromagnetic interference (EMI) shielding effectiveness (SE), reaching 17.8 ​S/m and 30.1 ​dB, respectively, when the content of the GNPs in the conductive layer was 20 ​wt%. The PASS/GNP composites also exhibited outstanding mechanical properties, which was attributed to the continuous PASS fiber skeletons that could withstand large loads and the strong interfacial interaction between the conductive layers and the PASS fibers that could provide good stress transfer. This approach is suitable for most soluble polymers.

Multi-functionalization is the future development direction for protective coatings on metal surface, but has not yet been explored a lot. The effective integration of multiple functions into one material remains a huge challenge. Herein, a superhydrophobic multilayer coating integrated with multidimensional organic-inorganic components is designed on magnesium alloy via one-step plasma-induced thermal field assisted crosslinking deposition (PTCD) processing followed by after-thermal modification. Hard porous MgO ceramic layer and polytetrafluoroethylene (PTFE) nano-particles work as the bottom layer skeleton and filler components separately, forming an organic-inorganic multilayer structure, in which organic nano-particles can be crosslinked and cured to form a compact polymer-like outer layer with hierarchical surface textures. Remarkably, the chemical robustness after prolonged exposure to aqua regia, strong base and simulated seawater solution profits from polymer-like nanocomposite layer uniformly and compactly across the film bulk. Moreover, the self-similar multilayer structure coating endows it attractive functions of strong mechanical robustness (>100th cyclic rotary abrasion), stable and ultra-low friction coefficient (about 0.084), high-temperature endurance, and robust self-cleaning. The organic-inorganic multilayer coating also exhibits high insulating property with breakdown voltage of 1351.8 ± 42.4 V, dielectric strength of 21.4 ± 0.7 V/µm and resistivity of 3.2 × 1010 Ω·cm. The excellent multifunction benefits from ceramic bottom skeleton, the assembly and deposition of multidimensional nano-particles, and the synergistic effect of organic inorganic components. This study paves the way for designing next generation protective coating on magnesium alloy with great potential for multifunctional applications.

In the preparation of plasma electrolytic oxidation (PEO) coating, the rapid heating of freely-happened electron avalanche under traditional discharge (TD) mode inevitably results in a strong eruption of electric breakdown melt. The PEO coating is loose and invariably composed of a very thin inner dense layer and an outer loose layer, as a result of which its properties and application have been limited greatly. In this work, for purpose of weakening the eruption of breakdown melt, thickening the inner dense layer, densifying the outer loose layer and improving the performance of PEO coating, ordinal discharge (OD) mode of PEO coating is developed by regulating the mass ratio of MgF2 to MgO (α) and voltage in the PEO investigation on AZ61 magnesium alloy in KF-KOH electrolyte. The formation mechanism under different discharge mode, electrochemical corrosion and wear of PEO coatings are investigated. The results show that the suitable α and voltage for effective OD are 1.3 and 130 V under which the freely-happened electron avalanche in MgF2 under TD mode can be restricted by the adequate adjacent MgO. Compared with TD mode, the inner dense layer, in which the ( 1 ¯ 0 1 ¯ ) plane of MgF2 is parallel to the (111) plane of MgO at their well-knit semi-coherent interface, is thickened to 2.4∼7.2 times, the corrosion potential (Ecorr) improvement is enlarged to 3.6∼13.2 times and the corrosion current intensity (Icorr) is reduced from 10.8∼9.499 to 0.433 (10−6 A/cm2). The outer loose layer is densified and the wear rate is lessened 65.5%∼89.8% by the evident melioration in surface porosity, impedance and hardness. This work deepens the understanding about the discharge of PEO coating and provides an available OD mode for preparing excellent PEO coating.

With the rapid development of the electronic industry, the requirements for packaging materials with high thermal conductivity (TC) are getting higher and higher. Epoxy is widely used as package material for electronic package applications. But it's intrinsic TC can't meets the increasing demands. Adding high TC graphene into epoxy matrix is a proper way to reinforce epoxy composites. This review focuses on the filler modification, preparation process and thermal properties of graphene-filled epoxy resin composites. Different ways of covalent and non-covalent modification methods are discussed. The various kinds of graphene coating layer are also summarized. Then we analysis the hybrid filler system in epoxy composite. We hope this review will provide guidance for the development and application of graphene-filled epoxy resin composites.

An Fe–10Cr–4Al alloy containing reactive elements developed for application in high-temperature liquid lead environments was analyzed after exposure in 600 and 750°C lead with dissolved oxygen for 1,000–2,000 h. Atom probe tomography, transmission electron microscopy, and X-ray scattering were all used to study the protective oxide formed on the surface. Exposure at 750°C resulted in a 2-μm thick oxide, whereas the 600°C exposure resulted in a 100-nm thick oxide. Both oxides were layered, with an Fe–Al spinel on top, and an alumina layer toward the metal. In the 600°C exposed material, there was a Cr-rich oxide layer between the spinel and the alumina. Metallic lead particles were found in the inner and middle parts of the oxide, related to pores. The combination of the experimental techniques, focusing on atom probe tomography, and the interpretations that can be done, are discussed in detail.

To explore the improving effect of Y2O3 on the water resistance of xY2O3-(100–x)(0.05Al2O3-0.15ZnO-0.15Na2O-0.65B2O3) (x = 0, 0.7 mol%, 1.4 mol%, 2.1 mol%, 2.8 mol%) glasses, glass structure and ion migration characteristics were respectively characterized by an infrared spectrometer and an electrochemical workstation. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and inductively coupled plasma atomic emission spectrometry (ICP-AES) were used to comprehensively analyze the alteration products. The experimental results show that with the increase of Y2O3 content, the mass loss per unit area of the glass is significantly reduced, and pH in leaching solution has the same change trend with mass loss of the glass, which indicates the improving effect of Y2O3 addition on the studied glass. The content of [BO4] structural unit and dc conductivity of glass increase firstly and then decrease with the increase of Y2O3 content, and reach a maximum at x = 0.7 mol%. Although addition of Y2O3 plays the role in the changes of glass structure and ion migration characteristics, the more important influence of Y2O3 is on the glass surface alteration layer. Y and Zn elements are enriched on the glass surface and finally transformed into an alteration layer, moreover, the adhesion between the alteration layers and the glass matrix is enhanced with the increase of Y2O3 content, which effectively blocks the further interdiffusion between the water molecules and the glass matrix.

Granular bed filters can effectively filter adhesive dust in high-temperature flue gas. In this study, polyvinyl chloride (PVC) powder was used as adhesive dust, and the mixture of PVC and ash powder was used to simulate solid and adhesive mixed dust. The effects of gas temperature, velocity, and inlet adhesive dust mass content on dust distribution in granular bed (GBF) were discussed. Results show that the mixed dust mainly accumulates on the upper part of the granular bed, and the mass of the collected dust decreases exponentially from the upper layer to the bottom layer in the GBF. The adhesive dust content collected in each layer differs from that of the incoming dust, and their deviation varies approximately linearly along with the depth of the bed. The total dust distribution and adhesive dust content deviation are influenced by gas temperature and inlet adhesive dust content but independent of gas velocity. The correlations of dust distribution of solid and adhesive mixed dust are presented based on the experimental results.

A modified technique for the growth of silicon carbide from silicon by the method of self-consistent substitution of atoms is proposed, which makes it possible to increase the achievable thickness of the formed silicon carbide layer by about an order of magnitude. The technique includes an additional step before the growth process: the surface of the silicon substrate is being saturated with vacancies by annealing in vacuum at T = 1350 ℃ for ~ 30 min. This leads to a change in the mechanism of mass transfer from the interstitial to the vacancy one when silicon atoms are being substituted by carbon atoms. As a result, not only the thickness of the silicon carbide layer increases, but also the separation of silicon carbide from the silicon substrate occurs if the thickness of the SiC layer surpasses 400 nm.

Hydroxyl terminated poly(dimethylsiloxane) (PDMS-HT) is used as an electrolyte additive in electrolyte systems containing 1 M LiPF6 in EC:DMC (ratios 1:9; 3:7; 4:6 and 1:1 v/v) to enhance the cycle performance of lithium-ion batteries. Adding a small amount of PDMS-HT to the standard LIB electrolyte leads to improved specific capacity as well as improved capacity retention over prolonged cycles. There is also a slight increase in Li+ ion conductivity when PDMS-HT is added. Also, the PDMS-HT additive allows the formation of a more stable solid electrolyte interface (SEI) layer that enables the LIB cells to be cycled for longer cycles with minimal capacity fading. This combination of improved ionic conductivity and stable SEI layer formation due to the PDMS-HT additive, makes it an excellent candidate for an electrolyte additive for lithium ion batteries.

Ruthner powder is a by-product of the steel hot-rolling process. This study introduces a new application area for this waste material by investigating its activity for the oxygen evolution reaction. Ruthner powder with the α-Fe2O3 phase structure was deposited on the carbon paper substrates using the electrophoretic deposition (EPD) process to fabricate the electrodes. The effect of the concentration of cetrimonium bromide ([CTAB]) and the Ruthner powder ([RP]) in the EPD cell on the morphology and activity of the electrodes were investigated by SEM, LSV, and EIS techniques. The results revealed the formation of a homogenous layer on the carbon paper when [CTAB] and [RP] were respectively 0.4 g.l−1 and 0.2 g.l−1. The obtained electrode showed the best activity among all fabricated electrodes. In particular, its onset overpotential and overpotential at a current density of 10 mA.cm−2 were respectively 85% and 25% lower than those of bare carbon electrodes.

Silicon-based nanosheets (SNS) were synthesised via a mild (60 °C) and time-saving (8 h) modified topochemical method. Then, Cu3(BTC)2 and SNS@Cu3(BTC)2 were successfully synthesised by microwave irradiation, and their characteristics and hydrogen storage performance were analysed by multiple techniques. The accordion-like SNS exhibited void spaces, a unique low buckled structure, and ultrathin, almost transparent, loosely stacked layers with a high specific surface area (362 m2/g). After in-situ synthesis with Cu3(BTC)2, the SNS compound achieved a high specific surface area (1526 m2/g), outstanding hydrogen storage performance (5.6 wt%), and a desirable hydrogen diffusion coefficient (10−7). Thus, SNS doping improved the hydrogen storage performance of Cu3(BTC)2 by 64% through electron transfer reactions with Cu enabled by the unique composite nanostructure of SNS@Cu3(BTC)2. This study presents a promising method of synthesising SNS and porous composite materials for hydrogen storage.

In sand casting, Fused Deposition Modeling (FDM) printing by using Poly Lactic Acid (PLA) filament is one of the innovative foundry technologies being adopted to substitute traditional pattern making. Several literatures have reported the influence of process parameters such as raster angle and print speed on some mechanical properties of FDM-printed, PLA-prototypes used in other applications. This study investigated the effects of interior fill, top solid layer, and layer height on the compressive strength of rapid patterns for sand casting application. Different values of the process parameters were used to print the pre-defined samples of the PLA-specimens and a compression test was performed on them. The coupled effects of the process parameters on compressive strength were investigated and the optimum values were determined. Interior fill of 36%, layer height of 0.21 mm and top solid layer of 4 were found to produce a FDM-printed, PLApattern that sustained a compaction pressure of 0.61 MPa. A simulation analysis with ANSYS® to compare failure modes of both experiment and model shows a similarity of buckling failure that occurred close to the base of each specimen.

This investigation aims to study a novel biologically derived coating applied on Ti alloy substrates. Obtained from a low-cost fish bone resource, a nanocrystalline hydroxyapatite has been synthesized and converted to an organic suspension. Coating was then manufactured by a high-velocity suspension flame spray process. The microstructure, phase composition, coating thickness, and roughness of hydroxyapatite (HA)-coated samples were studied. The results indicated the presence of both hydroxyapatite and β-tricalcium phosphate phases and the final coating layer was uniform and dense. In vitro bioactivity and biodegradability of the HA/Ti composite samples were estimated by immersion in simulated body fluid. Remarkable reductions in Ca2+ and PO43- ion concentrations were observed as well as low weight loss percentage and a slight variation in the pH value, indicating the generation of an apatite layer on the surface of all studied samples. Scanning electron microscopy, energy-dispersive x-ray analysis, and inductively coupled plasma–optical emission spectrometry confirm these results. Thus biological derived HA coatings are a promising candidate to enhance bioactivity and biodegradability of bone implants. To demonstrate feasibility on commercial medical components, a medical screw was coated and evaluated., Science & Technology Development Fund (STDF), Projekt DEAL

A flexible wireless electrocardiogram (ECG) device, integrated with fabric was fabricated for monitoring physiological signals in wearable biomedical applications. The ECG device consists of dry electrodes and a readout module. The dry electrode was fabricated by depositing multi-walled carbon nanotube (MWCNTs)/polydimethylsiloxane (PDMS) composite on a thermoplastic polyurethane (TPU) substrate with screen printed silver (Ag) layer. The readout module with wireless data transmission capability was designed and fabricated on a flexible polyimide substrate. The ECG device was attached to fabric, and its performance was investigated by measuring the ECG signals and comparing them with the results of conventional wet Ag/AgCl electrode. It was observed that the device demonstrated similar performance in terms of signal intensity and correlation when compared to the conventional wet ECG electrodes. Signal-to-noise-ratio (SNR) analysis clearly showed that the dry electrodes with an average SNR of 23.1 dB, perform better than the commercially available Ag/AgCl electrodes (SNR of 21.2 dB). In addition, the capability of the fabric based dry electrodes to measure ECG signals during the physiological activities under exercise motions was studied. This enabled understanding the effect of motion artifacts on the dry electrode response and allowed comparing the obtained ECG signals with the responses of conventional wet ECG electrodes (subjected to similar conditions). It was observed that, even though dry electrodes didn’t use any kind of adhesive gel for measuring the ECG signals, they performed very similar to conventional wet electrodes. The results obtained clearly demonstrated the feasibility of employing fabric based flexible dry ECG electrodes for continuous monitoring of ECG signals in health care applications and can potentially replace the wet electrodes.

In this work, a highly stable Ca2+ ion-selective sensor was successfully developed by depositing a poly(3,4-ethylenedioxythiophene): poly(styrene-sulfonate) (PEDOT:PSS) layer on top of a carbon paste electrode as an ion-electron transducing layer. The PEDOT:PSS was treated by a co-solvent of ethylene glycol (EG) using the bath-sonication technique to enhance electrical and electrochemical characteristics, and finally coated with Ca2+ ion-selective membrane cocktail. The developed Ca2+ ion-selective electrode (Ca2+-ISE) showed excellent electrochemical properties by much-improved charge transfer kinetics with remarkable electric conductivity. The fabricated Ca2+-ISE exhibited an excellent sensitivity of 37.7 mV/decade (n = 4) in the range from 10-4 to 10-1 M with a rapid response (< 20 seconds). Moreover, the EG-treated PEDOT:PSS (PEDOT:PSS-EG) based ISE showed negligible responses for primary interfering ions of human biofluid samples, proving significant potential selectivity. Furthermore, the negligible drift of open circuit potential (2.78 μV/s) proved the stability of the PEDOT:PSS-EG compared to pristine PEDOT:PSS(10.63 μV/s) based ISE. Based on these analyses, it can be expected that the organic solvent treatment on PEDOT:PSS will pave the way for long-term monitoring of other biochemical compounds.

Metallic nanolaminated materials possess excellent mechanical properties due to their unique modulation structures and interfacial properties. However, how microdefects affect their mechanical properties is still uncertain. To evaluate the influences of void location (in the crystalline layer and the Ti/Ni interface), void diameter (d) and thickness of the intermediate layer (h) on overall tensile behaviors, various types of defective Ti/Ni nanolaminates with pre-existing void are established by the molecular dynamics method in this work. The results indicate that the strength and plastic deformation mechanisms are strongly dependent on those determinants. Yield stresses of Ti/Ni nanolaminates decrease distinctly with increasing void diameter, while peak stresses with a void in the crystalline layer decrease with increasing d/h. Different void locations lead eventually to disparate initial plastic deformation carriers around the void, and various evolutions in the microstructure of the defective Ti/Ni nanolaminates. The Ti/Ni interface plays a significant role in the tensile process. The semi-coherent interface impedes new grains and lattice dislocations from passing across the interface, while the incoherent interface facilitates dislocations generating and sliding along the interface, and absorbs the dislocations moving to the interface. The results also indicate that the strain rate significantly affects the evolution of the microstructure and the tensile properties of defective Ti/Ni nanolaminates.

Perovskite solar cells (PSCs) have shown a significant increment in power conversion efficiency recently with advantages such as flexibility and low-cost roll-to-roll production. Prior to the commercialization of PSCs, it is significant to investigate its environmental performance with life cycle assessment method. In this work, cradle to gate LCA of solution-based organo-lead iodide perovskite solar cell performed according to the one reported literature method that comprises flexible Polyethylene terephthalate (PET) substrate and hole transport layer (HTL) elimination. Environmental impacts from the generation of 1 m2 of cell area production are determined in six International Reference Life Cycle Data System (ILCD) categories. It is found that the major impact comes from the fabrication of the aluminum metal electrode layer due to the high electrical energy required in the vacuum deposition process. The life cycle global warming potential (GWP) that the most widely used environmental indicator has been calculated for per kWh electricity production to make a comparison with commercial photovoltaic technologies. It is found that the HTL-free flexible (HFF) PSC needs 15-20 years of device lifetime to reach competitive GWP value with commercial PVs.

In this work, the microstructure of titania coating fabricated on the surface of hydrostatically extruded titanium grade 4 with the use of the micro-arc oxidation method was studied. The surface topography and microstructure investigations performed with atomic force microscopy and scanning and transmission electron microscopy revealed that, by using an Na2HPO4 electrolyte, a well-adherent porous coating is produced on the top surface and side walls of the extruded rod. The distribution of chemical elements was analyzed by using energy dispersive X-ray spectroscopy. The chemical elements dissolved in the electrolyte i.e. (Na, P and O) incorporated into the coating. Sodium locates preferentially in the outer part of the coating, while phosphorus and oxygen are distributed throughout the whole coating. The most relevant finding shows that a grain refinement caused by a hydrostatic extrusion provoked an increase in density of high-angle grain boundaries (HAGB), which in turn secured the formation of a continuous amorphous layer close to the substrate. The presence of this layer compensates for the effect of anisotropic substrate, producing a comparable and homogenous microstructure with a large number of micropores.

Permeable pavements play an important role in the mitigation of stormwater runoff and urban heat island effect. However, due to low strength and clogging, permeable pavements are always applied in light traffic areas. Therefore, it is necessary to understand the structural performance of permeable pavements under different conditions. In this paper, the performance of two permeable pavement structures (fully-permeable (FP) pavement and semi-permeable (SP) pavement) under dry and wet conditions is analyzed with the finite element method (FEM) modeling and one-third scaled MMLS3 test. A preliminary FEM model was established and empirical values of modulus are used. To make the model more closely simulate the actual conditions of the pavement, the modulus was calibrated according to the MMLS3 test results. The results of resilient strain and calibrated modulus of two structures under dry and wet conditions were analyzed, and the SP structure appears better cracking and moisture damage resistances. The modulus increases firstly and then decreases with the change of loading repetitions, which is considered to be caused by the combined action of further compaction of load and temperature. Since the change rate of surface layer modulus of the SP structure with loading repetitions is higher than that of FP structure, and only the base material of the two structures is different. It can be considered that the base layer modulus will affect the bottom strain of the surface layer, thus affecting the surface layer modulus. Furthermore, by calculating the difference between the base layer and the surface layer, it is found that the smaller the modulus gap between them, the smaller the change rate of the surface layer modulus.

Iron-based specimens with boronized layers were prepared by boriding at 800 ℃, 900 ℃ and 1000 ℃ for 3, 5, and 7 hours, respectively. The thickness, microstructure, surface roughness, friction, and wear performance were studied. Results showed that the process parameters such as temperature, the time of boriding have remarkable impact on the thickness of the boronized layer. Dual-phase was generated at 1000 ℃ which lead to increased brittleness, lower surface hardness, and decreased adhesion to the substrate. Compared with specimens boronized at 1000 ℃ and 800 ℃, the surface structure of the boronized layer of specimens boronized at 900 ℃ is denser and uniform, the wear track is not damaged. The average friction coefficient and mass loss by wear of specimens boronized at 900 °C are smaller than that of boronized at 1000 ℃ and 800 ℃, indicating that specimens borided at 900 ℃ behave excellent friction and wear performance.

The nonradiative recombination of charge carriers at the hole transport layer (HTL)/perovskite interface generally induces remarkable performance loss of the inverted two-dimensional perovskite solar cells (2D PSCs). Herein, a cross-linkable small molecule of 2-mercaptoimidazole (2-MI) was introduced into the nickel oxide (NiOx)/2D perovskite interface. Experiments have confirmed the formation of Ni-N covalent bond by N atom in the 2-MI and Ni in the NiOx and the coordinating between S atom of 2-MI and under-coordinated Pb2+ near to the NiOx/perovskite interface, which contributes to creating a cross-linking between NiOx/perovskite interface to restrain charge carrier recombination and enhance the extraction of hole carriers at the interface. Besides, the 2-MI modification layer is also beneficial for promoting the crystallinity of 2D perovskite. Consequently, the inverted 2D PSCs with 2-MI modification achieved the best power conversion efficiency of 15%. This paves a route to acquire highly efficient 2D PSCs by constructing a cross-linking at the NiOx HTL/2D perovskite interface.

There is keen interest in using Ti alloys as lightweight structural materials for aerospace and automotive industries. However, a long-standing problem for these materials is their poor oxidation resistance. Herein, we designed and fabricated a Ti5Si3 reinforced Ti-4(wt.%)Mo composite with two-scale network architecture by low energy milling and spark plasma sintering. It displays superior oxidation resistance at 800°C owing to the in-situ formation of a multi-component surface layer. This oxide layer has a dense grain size gradient structure that consists of an outer TiO2 layer and an inner SiO2-padding-TiO2 layer, which has remarkable oxidation resistance and thermal stability. Furthermore, it was revealed that the hitherto unknown interaction between Ti5Si3 reinforcement and nitrogen during oxidation would contribute to the formation of a TiN nano-twin interface layer, which accommodates the thermal mismatch strain between the oxide layer and matrix. This, along with high adhesion, confers excellent thermal cycling life with no cracking or spallation during long-term oxidation. In this regard, the secure operating temperature of this new composite can be increased to 800°C, which provides a design pathway for a new family of Ti matrix composites for high-temperature applications.

Self-assembled molecules (SAMs) have shown great potential in replacing bulk charge selective contact layers in high-performance perovskite solar cells (PSCs) due to their low material consumption and simple processing. Herein, we design and synthesize a series of donor-acceptor (D-A) type SAMs (MPA-BT-CA, MPA-BT-BA, and MPA-BT-RA, where MPA is 4-methoxy-N-(4-methoxyphenyl)-N-phenylaniline; BT is benzo[c][1,2,5]-thiadiazole; CA is 2-cyanoacrylic acid, BA is benzoic acid, RA is rhodanine-3-propionic acid) with distinct anchoring groups, which show dramatically different properties. MPA-BT-CA with CA anchoring groups exhibited stronger dipole moments and formed a homogeneous monolayer on the indium tin oxide (ITO) surface by adopting an upstanding self-assembling mode. However, the MPA-BT-RA molecules tend to aggregate severely in solid state due to the sp3 hybridization of the carbon atom on the RA group, which is not favorable for achieving a long-range ordered self-assembled layer. Consequently, benefiting from high dipole moment, as well as dense and uniform self-assembled film, the device based on MPA-BT-CA yielded a remarkable power conversion efficiency (PCE) of 21.81%. Encouragingly, an impressive PCE approaching 20% can still be obtained for the MPA-BT-CA-based PSCs as the device area is increased to 0.80 cm2. Our work sheds light on the design principles for developing hole selecting SAMs, which will pave a way for realizing highly efficient, flexible, and large-area PSCs.

The unique interactions between hexadecanoic acid (HA) and albumin (ALB) molecules on the surface of the porous layer of AZ31 Mg alloy were exploited to fabricate a novel hybrid composite film with excellent electrochemical stability in a 3.5 wt.% NaCl solution. Herein, the inorganic layer (IL) obtained by plasma electrolytic oxidation of AZ31 Mg alloy in an alkaline-phosphate-WO3 electrolyte was soaked in an organic solution composed of ALB and HA for 10 and 24 h at 60 °C. Although albumin and HA may coexist on the same surface of IL, the higher reactivity of ALB molecules would prevent the formation of a thick layer of HA. The donor-acceptor complexes formed due to the unique interactions between ALB and/or HA and IL surface would reduce the area exposed to the corrosive species which in turn would efficiently protect the substrate from corrosion. The porous structure of the IL would provide preferable sites for the physical and chemical locking triggered by charge-transfer phenomena, leading to the inhomogeneous nucleation and crystal growth of a flowery flakes-like organic layer. DFT calculations were performed to reveal the primary bonding modes between the ALB, HA, and IL and to assess the mechanistic insights into the formation of such novel hybrid composites.

Defining and visualizing the three-dimensional (3D) structures of pharmaceuticals provides a new and important tool to elucidate the phenomenal behavior and underlying mechanisms of drug delivery systems. The mechanism of drug release from complex structured dosage forms, such as bilayer osmotic pump tablets, has not been investigated widely for most solid 3D structures. In this study, bilayer osmotic pump tablets undergoing dissolution, as well as after dissolution in a desiccated solid state were examined, and visualized by synchrotron radiation micro-computed tomography (SR-μCT). In situ formed 3D structures at different in vitro drug release states were characterized comprehensively. A distinct movement pattern of NaCl crystals from the push layer to the drug layer was observed, beneath the semi-permeable coating in the desiccated tablet sample. The 3D structures at different dissolution time revealed that the pushing upsurge in the bilayer osmotic pump tablet was directed via peripheral “roadways”. Typically, different regions of the osmotic front, infiltration region, and dormant region were classified in the push layer during the dissolution of drug from tablet samples. According to the observed 3D microstructures, a “subterranean river model” for the drug release mechanism has been defined to explain the drug release mechanism.

In this study, functionally graded foam made of Inconel 625 superalloy was successfully produced using the template replication method, with open-cell polyurethane foams as a precursor. The products have a similar pore morphology as the templates and adjacent layers were successfully sintered together by particle bonding. Sound absorption experiments on graded metallic foams reveal that the sound absorption at particular frequency ranges can be improved by various permutations of foam layers. For graded foam of two distinct pore sizes, a mathematical equation was proposed to predict the location of the intersection point of the sound absorption curves, thereby aiding in graded foam design. An increase in sound absorption coefficients by resonance-like effects can be introduced before the intersection points by placing the foam layer of smaller pore size nearer to the sound source. The sound absorption performances can be further customized when the thickness proportion of the pore sizes is changed and when the number of distinct pore sizes used is increased. The sound absorption performance at lower frequencies is generally boosted by resonance-like effects when the layer of foam with the largest pore size is placed furthest from the sound source. Given the same composition of foam with a fixed thickness proportion of pore sizes, one can introduce resonance-like effects to improve the sound absorption performance compared to other permutations while possibly satisfying weight requirements in practical applications. This study provides valuable insights and mathematical guidelines in the design and manufacturing of functionally graded metallic foam for specific applications.

Heterogeneous gradient nanostructured metals have been shown to achieve the strength-ductility synergy, thus potentially possessing the enhanced tribological performance in comparison with their homogeneous nanograined counterparts. In this work, a facile laser surface remelting-based surface treatment technique is developed to fabricate a gradient nanostructured layer on a TiZrHfTaNb refractory high-entropy alloy. The characterization of the microstructural evolution along the depth direction from the matrix to the topmost surface layer shows that the average grain size in the ∼100 μm-thick gradient nanostructured layer is dramatically refined from the original ∼200 μm to only ∼8 nm in the top surface layer. The microhardness is therefore gradually increased from ∼240 HV in matrix to ∼650 HV in the topmost surface layer, approximately 2.7 times. Noticeably, the original coarse-grained single-phase body-centered-cubic TiZrHfTaNb refractory high-entropy alloy is gradually decomposed into TiNb-rich body-centered-cubic phase, TaNb-rich body-centered-cubic phase, ZrHf-rich hexagonal-close-packed phase and TiZrHf-rich face-centered-cubic phase with gradient distribution in grain size along the depth direction during the gradient refinement process. As a result, the novel laser surface treatment-introduced gradient nanostructured TiZrHfTaNb refractory high-entropy alloy demonstrates the significantly improved wear resistance, with the wear rate reducing markedly by an order of magnitude, as compared with the as-cast one. The decomposed multi-phases and gradient nanostructures should account for the enhanced wear resistance. Our findings provide new insights into the refinement mechanisms of the laser-treated refractory high-entropy alloys and broaden their potential applications via heterogeneous gradient nanostructure engineering.

The exploration towards cost-effective filler metal for ceramics joining has always been the key issues for ceramics joining. Herein, we reveal that the Al metal prefers to spread on the ZrO2 based ceramic under the air heating condition, due to the geometric limit effects by in-situ formed dense Al2O3 surface. Inspired by this, the joining of ZrO2 based ceramics was realized in air with Al metal as filler, through the diffusion of Al towards ceramic side. The Al element can induce obvious interfacial bonding effect on Al2O3 layer and ZrO2 ceramic, where the hybridization among the Al-p, Zr-d and O-p orbitals plays a key role. The in-situ formed Al2O3 layer on Al filler surface is vital for forming the fine interface (shear strength of ∼36 MPa), which results in the relief of lattice mismatch and peak stress at ceramic-filler metal transition interface.

Lightweight, scalable, mechanically flexible conductive polymer composite was always desirable for electromagnetic interference (EMI) shielding applications. In this work, we showcased a novel approach to the superior EMI shielding composite materials by orchestrating the multilayered structure and synergistic system. The asymmetric structure with the carbonyl irons (CI)-rich Ti3C2Tx/poly(vinylidene fluoride) (PVDF) magneto-electric layer jointly behind the Ti3C2Tx nanosheets filled PVDF layer was designed and fabricated in aid of a facile but efficient magnetic field-induced method and was then hot-pressed into multilayer structured film. Ti3C2Tx nanosheets were excluded by CI agglomeration layer in asymmetric film to form the complete 3D electrical conductive skeletons. Based on this strategy, EMI shielding properties of the asymmetric multilayer structured composite was superior to the homogeneous blend and sandwiched or alternating layered composites. In addition, an increase in CI content in the composite referred to the thickening of CI-rich layers, making it gain the most powerful EMI SE values, i.e. 42.8 dB for DCMP20-10 film (20 wt% CI, 10 wt% Ti3C2Tx) at 0.4 mm thickness. More importantly, the composite transformed from a reflection type to an absorption dominating EMI shielding material due to the multireflections and magneto-electric synergism in the CI-rich Ti3C2Tx/PVDF layers. Meanwhile, the EMI SE of the composites can be adjusted by not only increase of the overall thickness, but also the layer number of m-DCMP sheets. The thickness specific EMI SE was calculated as 165.25 dB mm−1 for 4-sheet composite film, a record high value amongst the high efficiency polymer-based EMI shielding materials. This method offered an alternative protocol for preferential integration of excellent EMI shielding performance with high mechanical performance in CPC materials.

Electromagnetic wave absorption (EWA) materials for use in extreme environments are of great interest. Herein, SiC nanowires / SiC whiskers (SiCnw/SiCw) foam with unique “wire-on-sphere” hierarchical structure was developed for efficient high-temperature EWA. SiCw were assembled to porous SiCw spheres via spray drying and then SiCw spheres were 3D printed to SiCw foam. The catalyst-free precursor infiltration pyrolysis process was first developed to ensure that SiCnw can intentionally grow in situ on the surface of SiCw spheres, thereby achieving “wire-on-sphere” hierarchical structure foam. At room-temperature, the maximum electromagnetic wave effective absorption bandwidth (EABmax) and minimum electromagnetic wave reflection coefficient (RCmin) of SiCnw/SiCw foam can reach 4 GHz and -57 dB, respectively. At 600 °C, the EABmax and RCmin were 3 GHz and -15 dB, respectively. Furthermore, even oxidized at 1000–1500 °C, SiCnw/SiCw foam can still retain EABmax ranging from 2.7 to 3.9 GHz and RCmin ranging from -16 dB to -64 dB, because the formation of SiO2 layer with appropriate thickness can boost interfacial polarization and regulate impedance matching. The SiCnw/SiCw foam also shows the flexural strength as high as 17.05 MPa. All results demonstrate that the SiCnw/SiCw foam is a promising EWA material for applications of harsh environments. And the material-independent “wire-on-sphere” hierarchical structure and its novel preparation process should find the widespread use in the design and fabrication of high-efficiency EWA micro-nano materials.

In this study, anode supported micro-tubular solid oxide fuel cells (SOFCs) are fabricated by extrusion method and the effects of powder size, thickness and sintering temperature of the anode functional layer (AFL) on the electrochemical performance is experimentally investigated. For this purpose, four different commercial NiO powders are tested as initial powder for the fabrication of the anode functional layer. The thickness of AFL is also considered by varying the number of coatings. After deciding the optimum initial NiO powder size used in AFL and AFL thickness, the effect of pre-sintering temperature is examined. The performance tests are performed at an operating temperature of 800 °C under hydrogen and air. The microstructures of the samples are also investigated by a scanning electron microscope. The best peak power density is obtained as ∼0.5 W/cm2 from the cell having a single layer anode functional layer pre-sintered at 1250 °C prepared by NiO powders with 4 m2/g surface area.

The article describes the technology development of layered surface compositions, including a high-entropy layer of a material with high-temperature memory effect of TiNiZrHfCoCu and a high-temperature ceramic layer based on zirconium dioxide ZrO2 stabilized by Y2O3. The authors also studied the structure, functional and mechanical properties of the abovementioned compositions. The proposed technology was implemented on a patented multifunctional technological complex for the formation of composite layered materials on the surface of steel products in a single technological cycle. On the basis of complex X-ray diffraction and electron microscopic studies, the structural parameters of the constituent layers of the surface composition were determined with subsequent thermal and thermomechanical treatment. The tests for ‘friction-wear’ and mechanical multi-cycle fatigue of the constituent layers of the surface composition showed a decrease in wear intensity and an increase in cyclic durability compared to the steel base. The comparison of wear intensity and cyclic durability of the surface-modified layers of the layered composition TiNiZrHfCoCu-ZrO2(Y2O3) with the composite materials obtained and studied by the authors earlier allowed the recommendation of the surface composition ‘high-entropy alloy TiNiZrHfCoCu-high-temperature ceramics’ for products of various purposes.

Flexible aqueous energy storage devices with high security and flexibility are crucial for the progress of wearable energy storage. Particularly, aqueous rechargeable Ni-Fe batteries owning a large theoretical capacity, low cost and outstanding safety characteristics have emerged as a promising candidate for flexible aqueous energy storage devices. Herein, Cu-doped Fe3O4 (CFO) with 3D coral structure was prepared by doping Cu2+ based on Fe3O4 nanosheets (FO). Furthermore, the Fe-based anode material (CFPO) grown on carbon fibers was obtained by reconstructing the surface of CFO to form a low-crystallization shell which can enhance the ion transport. Excitingly, the newly developed CFPO electrode as an innovative anode material further exhibited a high capacity of 117.5 mAh g−1 (or 423 F g−1) at 1 A g−1. Then, the assembled aqueous Ni-Fe batteries with a high cell-voltage output of 1.6 V deliver a high capacity of 49.02 mAh g−1 at 1 A g−1 and retention ratio of 96.8% for capacitance after 10 000 continuous cycles. What's more, the aqueous quasi-solid-state batteries present a remarkable maximal energy density of 45.6 Wh kg−1 and a power density of 12 kW kg−1. This work provides an innovative and feasible way and optimization idea for the design of high-performance Fe-based anodes, and may promote the development of a new generation of flexible aqueous Ni-Fe batteries.

Aqueous zinc anodes have attracted the attention of many researchers owing to their high safety, low cost, and high theoretical specific capacity. However, its practical application is severely limited by the dendrite growth on zinc anode. Herein, we develop an intrinsically zincophobic barium-titanate protective layer with a porous structure to suppress the zinc dendrite formation by homogenizing the ion distribution on the anode surface, increasing the nucleation sites, and limiting the irregular zinc growth. Based on these synergistic effects, the coated zinc anode can exhibit long cycle life (840 h at 0.5 mA/cm2 for 0.5 mAh/cm2) and low voltage hysteresis (36 mV). This work can provide a feasible direction for the design of intrinsically zincophobic coating materials to uniformize the zinc stripping and plating.

With rapid development of marine infrastructures, materials with better biocorrosion resistance and antibiofouling performance will be highly demanded. Ti6Al4V alloy is susceptible to the above. The inhibition to the microbiologically influenced corrosion of Ti6Al4V-5Cu alloy against Pseudomonas aeruginosa was investigated using antibacterial test, electrochemical techniques, surface analysis, and weight loss test conducted for 2.5 months. At a sputtering depth of 0 nm, the passive film of Ti6Al4V-5Cu alloy was mainly composed of ideal oxide TiO2. With increasing sputtering thickness to 6 nm, Ti2O3 and TiO were detected with a relative fraction of 14.6% and 14.8%, respectively, in the oxide layer of Ti6Al4V-5Cu alloy. In contrast, the outermost layer of Ti6Al4V alloy was predominantly composed of TiO2 but Ti2O3 (22.8%), Al2O3 and V2O5 were also detected. With increasing sputtering depth to 6 nm, fitting revealed the presence of Ti2O3 and TiO with relative fractions of 25.3% and 35.8%, respectively. Yet, a spot of TiO (8%) was also observed at 12 nm in the oxide layer of Ti6Al4V alloy. Although the addition of Cu into Ti6Al4V alloy generated the self-healing property of passive film in the presence of P. aeruginosa, it also reduced resistance to corrosion in general condition.

Isothermal oxidation behaviors of Ni–Fe (wt.%) and of the same alloy with additions of 10 and 15%Cr alloys in the air at 800 °C and 900 °C and their anodic behaviors in aluminum electrolysis system at 800 °C were evaluated. The composition morphologies of oxide scales were characterized by XRD, SEM, and EDS. Results show that the scales formed on Ni–Fe alloy at both temperatures consisted of an inner (Ni,Fe)3O4 layer and an outer Fe2O3 layer. For Ni–Fe–10Cr alloy, an external (Ni,Fe)3O4/Fe2O3 layers and an internal oxidation zone were formed at 800 °C, while a continuous Cr2O3 layer forms at the internal oxidation zone/substrate interface at 900 °C. A multilayer structure oxide of Cr2O3/(Ni,Fe,Cr)3O4/(Ni,Fe)3O4/Fe2O3 was formed on Ni–Fe–15Cr alloy at 800 °C, while at 900 °C the Fe2O3 becomes discontinuous disperses in the (Ni,Fe)3O4 layer close to the surface. Increases in oxidation temperature or Cr content for Ni–Fe–Cr alloys promote the growth of the inner Cr2O3 layer and simultaneously reduce Fe2O3 content. After 4 h of electrolysis at an anode current density of 0.25 A cm−2, the oxidation resistance of Ni–Fe–15Cr anode is superior to the Ni–Fe anode.

Ultrastrong nanolayered metallic composites are usually subjected to low ductility due to plastic instability during deformation. Here we investigated the shear instability of a newly designed heterogeneous nanolayered Cu/Zr composites by microindentation. The heterogeneity in size was generated by inserting a few thin Cu-Zr bilayers with an individual layer thickness of 2.5 - 10 nm into the interface region of the Cu/Zr layered composites with an individual layer thickness of 100 nm. The microindentation tests showed that multiple shear bands appeared in the heterogeneous composite with one bilayer, whereas only a single shear band was formed in that with two or three bilayers. Most importantly, the layer strain in the multi-shear band region is much smaller than that in the single-shear band area. For example, the strain of the 100 nm layers within the shear band in the composite with one 10 nm bilayer could reach as low as 2.8, which was less than half of that in the composite with three 10 nm bilayers, i.e., 6.1. These findings demonstrated that strain delocalization can be achieved through shear band multiplication if an appropriate number of thin bilayers were used as interlayers in the 100 nm Cu/Zr composites. Besides, compared with the homogeneous composite with an individual layer thickness of 100 nm and the bimodal composite which is composed of alternating one 100 nm Cu-Zr bilayer and two 10 nm Cu-Zr bilayers, the heterogeneous composite with one bilayer displayed a higher strength (2.15 GPa) and a favorable resistance to strain localization.

With the ever-growing application of lithium-ion batteries (LIBs), their fast-charging technology has attracted great interests of scientists. However, growth of lithium dendrites during fast charge of the batteries with high energy density may pose great threats to the operation and cause serious safety issues. Herein, we prepared a functional separator with an ultra-thin (20 nm) layer of Au nanoparticles deposited by evaporation coating method which could regulate growth direction and morphology of the lithium dendrites, owing to nearly zero overpotential of lithium meal nucleation on lithiated Au. Once the Li dendrites are about to form on the graphite anode during fast charging (or lithiation), they plate predominantly on the Au deposited separator rather than on the graphite. Such selective deposition does not compromise the electrochemical performance of batteries under normal cycling. More importantly, it enables the better cycling stability of batteries at fast charge condition. The Li/Graphite cells with Au nanoparticles coated separator could cycle stably with a high areal capacity retention of 90.5% over 95 cycles at the current density of 0.72 mA cm−2. The functional separator provides an effective strategy to adjust lithium plating position at fast charge to ensure high safety of batteries without a compromise on the energy density of LIBs.

The multilevel storage capability of nonvolatile resistive random access memory (ReRAM) is greatly desired to accomplish high functioning memory density. In this study, Ta2O5 thin film with different thicknesses (2, 4, and 6 nm) was exploited as an appropriate interfacial barrier layer for limiting the formation of the interfacial layer between the 10 nm thick sputtering deposited resistive switching (RS) layer and Ta ohmic electrode to improve the switching cycle endurance and uniformity. Results show that lower forming voltage, narrow distribution of SET-voltages, good dc switching cycles (103), high pulse endurance (106 cycles), long retention time (104 s at room temperature and 100°C), and reliable multilevel resistance states were obtained at an appropriate thickness of ∼2 nm Ta2O5 interfacial barrier layer instead of without Ta2O5 and with ∼4 nm, and ∼6 nm Ta2O5 barrier layer, ZrO2-based memristive devices. Besides, multilevel resistance states have been scientifically investigated via modulating the compliance current (CC) and RESET-stop voltages, which displays that all of the resistance states were distinct and stayed stable without any considerable deprivation over 104 s retention time and 104 pulse endurance cycles. The I-V characteristics of RESET-stop voltage (from −1.7 to −2.3 V) of HRS are found to be a good linear fit with the Schottky equation. It can be seen that Schottky barrier height rises by increasing the stop-voltage during RESET-operation, resulting in enhancing the data storage memory window (on/off ratio). Moreover, RESET-voltage and CC control of HRS and LRS revealed the physical origin of the RS mechanism, which entails the formation and rupture of conducting nanofilaments. It is thoroughly investigated that proper optimization of the barrier layer at the ohmic interface and the switching layer is essential in memristive devices. These results demonstrate that the ZrO2-based memristive device with an optimized ∼2 nm Ta2O5 barrier layer is a promising candidate for multilevel data storage memory applications.