Search

The best choice today for a realistic method of increasing the energy density of a metal-ion battery is to find novel, effective electrode materials. In this paper, we present a theoretical investigation of the properties of hitherto unreported two-dimensional B 3 C 5 and N 3 C 5 bilayer systems as potential anode materials for lithium-ion batteries. The simulation results show that N 3 C 5 bilayer is not suitable for anode material due to its thermal instability. On the other hand B 3 C 5 is stable, has good electrical conductivity, and is intrinsically metallic before and after lithium intercalation. The low diffusion barrier (0.27 eV) of Li atoms shows a good charge and discharge rate for B 3 C 5 bilayer. Moreover, the high theoretical specific capacity (579.57 mAh/g) connected with moderate volume expansion effect during charge/discharge processes indicates that B 3 C 5 is a promising anode material for Li-ion batteries. [ABSTRACT FROM AUTHOR]

Context: In this study, the electronic structure and diffusion barrier of the Ca-adsorbed WTe2 system under different torsion angles were calculated based on the first-principles method. The results show that the structure and properties of the pure WTe2 system and Ca-adsorbed WTe2 system are affected by torsional deformation. When the torsion angle is 6°, the intrinsic WTe2 changes from a direct band gap to an indirect band gap. The torsional deformation does not change the metallicity of the Ca-adsorbed WTe2 system. The Ca-d state electrons contribute to the electron density of WTe2. The calculation of the diffusion barrier shows that the torsion deformation promotes the diffusion of calcium on the surface of WTe2. This study provides a theoretical basis for the regulation of electrode materials. Methods: In this study, Materials Studio 8.0 software was used to construct the WTe2 model and Ca-adsorbed WTe2 model, and CASTEP module was used for first-principles calculation. [ABSTRACT FROM AUTHOR]

Context: In this study, the electronic structure and diffusion barrier of Ca adsorbed MoTe2 system under different degrees of shear deformation were calculated based on the first-principles method. The results show that both the pure MoTe2 system and Ca-adsorbed MoTe2 system are affected by shear deformation. The pure MoTe2 undergoes a transition from direct to indirect band gap under shear deformation. The adsorption of Ca makes MoTe2 changes from semiconductor to quasi-metal. The results of the density of states show that Ca insertion makes the conduction band part of the adsorption system significantly enhanced. The diffusion barrier of Ca through MoTe2 indicates that the shear deformation promotes the diffusion of Ca on the surface of MoTe2. Shear deformation can effectively modulate the electronic properties of the MoTe2 system, which provides a theoretical basis for the application of MoTe2 materials in the field of ion batteries. Methods: In this study, Materials Studio 8.0 software was used to construct the MoTe2 model and Ca adsorbed MoTe2 model, and the CASTEP module was used for first-principles calculation. [ABSTRACT FROM AUTHOR]

Packaging is very important to maintain the quality of food and prevent the growth of microbes. Therefore, the use of food packaging with antimicrobial properties protects the food from the growth of microorganisms. In this study, antibacterial nanocomposite films of polyvinyl alcohol/starch/chitosan (PVA/ST/CS) together with nickel oxide-copper oxide nanoparticles (NiO–CuONPs) are prepared for food packaging. NiO–CuONPs were synthesized by the co-precipitation method, and structural characterization of nanoparticles (NPs) was carried out by XRD, FTIR, and SEM techniques. Composites of PVA/ST/CS, containing different percentages of NPs, were prepared by casting and characterized by FTIR and FESEM. The mechanical properties, diffusion barrier, and thermal stability were determined. The nanoparticles have a round structure with an average size of 6.7 ± 1.2 nm. The cross-section of PVA/ST/CS film is dense, uniform, and without cracks. In the mechanical tests, the addition of NPs up to 1% improved the mechanical properties (TS = 31.94 MPa), while 2% of NPs lowered TS to 14.76 MPa. The fibroblast cells toxicity and the films antibacterial activity were also examined. The films displayed stronger antibacterial effects against Gram-positive bacteria (Staphylococcus aureus) compared to Gram-negative bacteria (Escherichia coli). Furthermore, these films have no toxicity to fibroblast cells and the survival rate of these cells in contact with the films is more than 84%. Therefore, this film is recommended for food packaging due to its excellent mechanical and barrier properties, good antibacterial activity, and non-toxicity. [ABSTRACT FROM AUTHOR]

Primary cilia act as cell surface antennae, coordinating cellular responses to sensory inputs and signalling molecules that regulate developmental and homeostatic pathways. Cilia are therefore critical to physiological processes, and defects in ciliary components are associated with a large group of inherited pleiotropic disorders — known collectively as ciliopathies — that have a broad spectrum of phenotypes and affect many or most tissues, including the kidney. A central feature of the cilium is its compartmentalized structure, which imparts its unique molecular composition and signalling environment despite its membrane and cytosol being contiguous with those of the cell. Such compartmentalization is achieved via active transport pathways that bring protein cargoes to and from the cilium, as well as gating pathways at the ciliary base that establish diffusion barriers to protein exchange into and out of the organelle. Many ciliopathy-linked proteins, including those involved in kidney development and homeostasis, are components of the compartmentalizing machinery. New insights into the major compartmentalizing pathways at the cilium, namely, ciliary gating, intraflagellar transport, lipidated protein flagellar transport and ciliary extracellular vesicle release pathways, have improved our understanding of the mechanisms that underpin ciliary disease and associated renal disorders. The compartmentalized structure of primary cilia is maintained via interconnected barrier and active transport systems and underlies its unique composition and function. This Review describes the major compartmentalizing pathways that occur at the cilium and how insights into cilia transport and barrier mechanisms have shed light on the mechanisms underlying ciliary diseases. Key points: Cilia at the cell plasma membrane serve motility, sensory and signalling roles that are essential for cell and tissue formation, homeostasis and function. Cilia defects cause ciliopathy disorders that affect many tissue types. The unique and dynamic molecular composition of the ciliary organelle and its biochemically compartmentalized state are established and maintained via interconnected barrier and active transport systems. The ciliary base, which encompasses the transition zone and basal body regions, and associated 'gating' complexes (MKS, NPHP, TAF and NUP modules), establish barriers to regulate the movement of cytosolic and membrane proteins into and out of cilia. Membrane and cytosolic proteins move into and out of cilia by binding to cargo adaptor complexes (intraflagellar transport (IFT)-A, IFT-B and the BBSome) present on kinesin-2 and cytoplasmic dynein-driven IFT trains that run bidirectionally along ciliary microtubules. Myristoyl-anchored and palmitoyl-anchored membrane proteins enter cilia via lipidated IFT, which involves shuttling carriers (UNC119B and PDE6D), cargo displacement factors (ARL3) and associated regulators (RP2 and ARL13B). Extracellular vesicles that bud from the ciliary membrane regulate ciliary structure, composition and function by dispatching molecules and membrane from the organelle. Ciliary extracellular vesicles may serve as waste disposal and/or cell–cell communication devices. Better knowledge of the ciliary compartmentalization pathways is essential for understanding mechanisms of ciliary disease such as the renal ciliopathies that include autosomal dominant polycystic kidney disease and nephronophthisis. [ABSTRACT FROM AUTHOR]

Context: Transition metal chalcogenides are excellent anode materials for calcium ion batteries (CIBs). In this study, the structural stability, electronic structure, and diffusion barrier of bulk XTe2 (X = Mo, W) were studied by first-principles calculations within the framework of density functional theory. The density of states analysis shows the metal behavior of XTe2 (X = Mo, W) during calcification. The voltage ranges of CayMoTe2 and CayWTe2 are 1.53–0.45 V and 1.48–0.41 V (y = 0–5), respectively. The diffusion barrier of Ca+ through XTe2 indicates that the compressive strain promotes the diffusion of calcium through XTe2. XTe2 is considered to be a promising electrode material for CIBs. Methods: In this paper, the transition metal chalcogenides model is constructed by Material Studio 8.0, and the first-principles calculation is carried out by CASTEP module. [ABSTRACT FROM AUTHOR]

Diffusion barrier coating (DBC) systems on heat resistant alloys consist of a multi-layer structure: an outer Al-reservoir layer and an inner diffusion barrier layer (DBL). The outer Al-reservoir layer forms a protective Al2O3 scale and DBL acts as a barrier layer against alloy interdiffusion. Three kinds of DBL were developed: Re on Ni-based superalloys; W on stainless steels; and Cr on Ni–Cr alloys. It was found that DBC systems have excellent mechanical properties (creep and fatigue), improving alloy substrate performance, and enhance the anti-exfoliation properties of YSZ in thermal barrier coatings (TBC) in addition to providing excellent oxidation resistance. At temperatures higher than 1300 °C, however, the DBC design based on kinetics (diffusion) is insufficient to form and maintain a protective Al2O3 scale. In this case a self-maintaining coating (SMC) system designed on the basis of thermodynamics (phase stability) is required. The SMC system formed on Nb–Hf (C-103) alloy consists of a multi-layer structure: an outer Re (Al, Si)1.8 and inner NbSi2 layers, plus a transient Nb5Si3 layers formed during oxidation. At temperatures higher than 1300 °C the Al2O3 can be formed by changing the Al/Si ratio in the Re (Al, Si)1.8 in which Si was supplied from the decomposition reaction of NbSi2 to Si + Nb5Si3 during selective oxidation of Al. It is proposed that coating alloys should be designed for considering not only high temperature oxidation, but also alloy substrate mechanical properties and anti-exfoliation of oxide scales, based on both kinetic principles (DBC system) and thermodynamics (SMC system). [ABSTRACT FROM AUTHOR]

The service of protective coatings at high temperature will lead to interdiffusion between the coating and superalloy. The occurrence of interdiffusion not only reduces the oxidation resistance of the coating but also reduces the mechanical properties of superalloys, especially single crystal superalloys. At present, the main methods of suppressing interdiffusion are: adding a diffusion barrier layer between the coating and superalloy, a so-called "equilibrium" (EQ) coating, and a nanocrystalline coating. In the current review, the advantages and disadvantages of these three methods for suppressing interdiffusion are discussed, and an attempt is made to determine the best method for suppressing interdiffusion to improve the service life of high-temperature components. [ABSTRACT FROM AUTHOR]

Owing to good physical compatibility with high-temperature metallic structural materials, Cr2O3- or Al2O3-forming MCrAlY coatings have been extensively used to protect hot section components in aerospace and other fields from high-temperature corrosion. Currently, MCrAlY coatings are normally manufactured by means of physical methods, including electron beam-physical vapor deposition, magnetron sputtering, ion plating, thermal spray, etc. This review paper introduces novel nanocomposite-type MCrAl(Y) coatings prepared by electrochemical methods of nanocomposite electrodeposition and further modified "electrophoretic deposition + electrodeposition." The novel MCrAl(Y) coatings exhibit apparently enhanced ability in protective chromia or alumina scale formation, which can be attributed to the two-fold "nanoscale effect" of the dispersed particles and metal matrix grains. Based on a large amount of oxidation data of the nanocomposite-type NiCrAl coatings under different oxidation conditions, oxide maps showing the relationship between coatings' composition and type of the oxides are constructed to offer guidance for designing the novel coatings. Moreover, the "electrophoretic deposition + electrodeposition" method has been further applied to conveniently integrate a metallic-ceramic diffusion barrier into a MCrAl(Y) coating/Ni-based superalloy system which can significantly block the interdiffusion between the coating and the matrix. [ABSTRACT FROM AUTHOR]

The article develops the possibility of forming silicon oxide structures with tapered walls using dry etching methods, including a two-stage process involving the formation of a tapered photoresist mask and plasma etching of the silicon oxide. A study of the process of tapered resist etching was carried out. The influence of plasma parameters and composition on the etching process was studied, plasma diagnostics were carried out using Langmuir probe and optical emission actinometry methods, and the mechanisms of tapered resist etching were suggested. The etching process was optimized and structures with a resist thickness of 400 nm and a sidewall angle of up to 61° were obtained. A subsequent SiO2 etching process allowed the slope of the resist to be transferred. The slope of the SiO2 wall was 57°. The resulting structures with tapered SiO2 walls make it possible to produce capacitors for studying the characteristics of dielectrics, as well as the structure of microelectromechanics and microfluidics. [ABSTRACT FROM AUTHOR]

Various transition metal dichalcogenides materials have been investigated from bulk to monolayer phases for different advanced technological applications. Tin disulfide monolayer offers advantages as an anode material for Li/Na-ion batteries, although it cannot be considered ideal for direct exploitation. We systematically performed a comparative study of the adsorption and diffusion behaviour of Li/Na on a pristine SnS 2 monolayer and on a SnS 2 monolayer with S-vacancy for enhancement of electrochemical performance, using density functional theory approach. Although all the adsorption sites are exothermic, it was established that Li/Na adatoms mostly prefer to bind strongly on SnS 2 monolayer with S-vacancy but avoiding the S-vacancy site. It was established that avoiding the S-vacancy site along the path, excellent diffusion barriers of 0.19 eV for Li and 0.13 eV for Na were achieved, suggesting possible ultrafast charge/discharge rate. Due to reduced molar mass, the SnS 2 monolayer with S-vacancy has a slightly higher storage capacity than its pristine counterparts for both Li and Na adatoms. The obtained open circuit voltage values are within the range of 0.25–3.00 V assuring that the formation of dendrites can surely be averted for the envisaged battery operation. Understanding the effects of an S-vacancy on the electrochemical properties of Li/Na on the SnS 2 monolayer allows us to consider possible improvements to energy storage devices that can be applied as a result of improved anode material. [ABSTRACT FROM AUTHOR]

A two-layer Fe–Cr–Al–Zr surface alloy has been synthesized on a zirconium substrate by magnetron sputtering and subsequent low-energy high-current electron-beam (LEHCEB) processing. The thicknesses of the top Fe69Cr20Al11 (at.%) relatively large-grained (~1 μm) layer and the transition Fe–Zr–Cr–Al amorphous layer were about 0.7 and 0.6 μm, respectively. In turn, the amorphous layer consisted of two Fe64–54Zr8–22Cr21–17Al8–7 and Fe40–16Zr42–78Cr12–4Al6–2 (at.%) sublayers that differed in both zirconium and iron concentrations in wide ranges and were separated by another nanocrystalline interlayer. The Fe–Cr–Al–Zr surface alloy served as the diffusion barrier preventing the interaction of the zirconium substrate with oxygen from an environment. It was thermally stable up to ≈1173 K. [ABSTRACT FROM AUTHOR]

To examine the suitability of diboron porphyrin (DP) for aluminum-ion batteries (AIBs), the adsorption of AlCl4 on DP monolayer is studied using the density functional theory (DFT) computations. The strength of AlCl4 adsorption on DP is found comparable to graphene and slightly more than graphdiyne. The thermal stability of AlCl4 molecules on DP sheets at temperatures as high as 500 K is verified by ab-initio molecular dynamics (AIMD) simulations. A theoretical capacity of 337 mAhg−1 is predicted for AIBs based on DP monolayer. The semiconducting properties of a DP single layer change to metallic after the adsorption of AlCl4. This indicates that AlCl4 adsorption enhances the electrical conductivity of DP which is necessary for electrode material in AIBs. The low diffusion barrier with low voltage confirms the fast charging and discharging processes in the DP-based AIBs. Our results prove that a monolayer of DP can be a proper cathode material in AIBs. [ABSTRACT FROM AUTHOR]

The diffusivity in the upper Cu-Chabazite layer of a dual layer ammonia oxidation catalyst with a lower Pt layer was investigated. In a first step, the pore structure of the upper Cu-Chabazite catalyst layer was determined by Focused Ion Beam-Scanning Electron Microscopy (FIB-SEM) slice&view tomography. From the FIB-SEM data the 3D pore structure of the catalyst was reconstructed and diffusion simulations were performed on the reconstructed pore geometry, resulting in an estimated effective diffusivity of Deff/Dgas = 0.31. To validate the FIB-SEM derived estimates of the diffusivity, measurements of CO oxidation on the dual layer catalyst were performed, where the CO was oxidized in the lower Pt-layer while the upper SCR layer served as an inactive diffusion barrier. In this way, the effective diffusivity can be determined from the measured CO conversion. An effective diffusion coefficient of Deff/Dgas = 0.11 was obtained from the CO oxidation measurements, three times lower than the value obtained from the FIB-SEM data, but in line with previous literature data for the effective diffusivity in monolith washcoat layers. Additional NH3 oxidation experiments were performed on the dual layer catalyst. The results were well reproduced by a reactor model applying the effective diffusion coefficient obtained by the CO oxidation experiments. The origin of this apparent inconsistency is currently not understood and requires further investigation. [ABSTRACT FROM AUTHOR]

In this contribution, we describe the kinetics associated with the rac-Me2Si[2-Me-4-Ph-Ind]2ZrCl2 (Cat-1)/borate/TIBA catalyzed copolymerization of E/dienes (isoprene (IP), butadiene (BD), 5-ethylidene-2-norbornene (ENB), 4-vinylcyclohexene (VCH) and vinyl norbornene (VNB)), and E/diene/1-hexene (1H) terpolymerization by using thiophenecarbonyl chloride (TPCC) that was used in Ziegler-Natta (Z-N) and metallocene-catalyzed polyethylene (PE) and polypropylene (PP) and E/P polymerizations. In both types of polymerizations, a higher amount of dienes was incorporated when VNB (2.70 mole %) and VCH (1.56 mole %) were added as comonomer, but IP and BD were incorporated with the moderated rate (0.6-1.1 mole %) with higher activities (3.45x106gm/mmolMt·h). The active center [Zr]/[C*] fraction is higher (61%) than previously reported PE polymerizations, especially in the case of E/IP, E/BD and E/IP/1H but lower than E/P (87%) copolymerization. Significantly, IP and BD activated the inactive catalytic sites that were dormant in the PE. The propagation rate constant (kpE) with IP was higher (kp564 Lmol-1s-1), while kpE with VNB (kp379 Lmol-1s-1) and VCH (kp304 Lmol-1s-1), which were lower than PE. This difference is built because of the diffusion barrier in the system. Compared to E/diene copolymers, kpE values in E/diene/1H terpolymerizations for IP, VCH, and VNB are higher and stable except ENB and determine that 1H prevents the insertion of dienes and reduces the crystalline properties resultant moderate kpE. Even though the E/BD copolymers decreased butadiene content of over 2 mol% resulted in better crystalline characteristics, lower diffusion barriers, and a higher kpE value. In concept, IP and BD are linear and readily available for coordination. While VCH, ENB and VNB are cyclic and bulky, metallocene in contact ion pairs cannot accept ENB, VNB, and VCH for coordination and subsequently act as dormant in the polymerization. [ABSTRACT FROM AUTHOR]

Sb2Te3 is an important thermoelectric material. Co is a potential diffusion barrier. This study examined the electroplated Co/Sb2Te3 interfacial reactions at 300 °C, 400 °C and 500 °C. To provide fundamental information and for better understanding the reaction paths, the Co-Sb-Te phase equilibria isothermal sections at these three temperatures are proposed. No ternary compound is found. The 400 °C isothermal section contains (Co), (Sb), (Te), β-CoSb, β-Co1−xTe, CoSb3, δ-(Sb2Te), γ-(SbTe), Sb2Te3 and a continuous solid solution γ-Co(Sb,Te)2. At 500 °C, except for Te being molten, the phase relationships are similar to those at 400 °C. At 300 °C, although γ-CoSb2 and γ-CoTe2 have very significant mutual solubilities, they are two separate phases and do not form a continuous solid solution. In the Co/Sb2Te3 couple reacted at 300 °C, only one reaction phase, γ-CoTe2 with Sb solubility, is formed. Similar results are found in the Co/Sb2Te3 couple reacted 400 °C, and the reaction phase is the continuous solid solution γ-Co(Sb,Te)2. Two reaction phases, β-Co1-xTe and γ-Co(Sb,Te)2, are found in the couple reacted at 500 °C. The compositional ratio of Sb/Te in the reaction phase remained at 2/3 indicates that Co is the dominating diffusion species. The reaction phases are formed rapidly by Co penetration into the Sb2Te3 substrate. A peculiar phenomenon was found with the reaction layer that formed on the side of Co that was not in direct contact with the Sb2Te3 substrate which will be further investigated. [ABSTRACT FROM AUTHOR]

In this work, we have investigated the electrochemical characteristics of armchair silicon carbide nanoribbon (ASiCNR) for its potential deployment as 2D lithium-ion battery anode material. Density functional theory approach is used to calculate the adsorption energy, storage capacity, and open circuit voltage of ASiCNR for LIB. Adsorption of Li atoms introduces the new energy bands which cross the Fermi level; this results in semiconductor to metallic transition of ASiCNR. It indicates the strong interaction of Li atoms towards the ASiCNR. When adsorption of Li atoms increases one by one, the adsorption energy (E ads ) per Li atoms increases gradually. When all favourable sites are adsorbed by Li atoms E ads reached its maximum value and it results in maximum storage capacity of 818 mAhg - 1 and open circuit voltage of 1.15 V. Diffusion barrier of Li atoms for the substrate is 0.42 eV. Our computational results suggest that ASiCNR can be used as an anode material for Li-ion batteries, and it provides the theoretical background for the future study on ASiCNR and other Li storage structures. [ABSTRACT FROM AUTHOR]

Exploring the excellent anode materials for metal-ion batteries is a hot spot in the energy storage field. Based on first-principles calculations, we propose two-dimensional (2D) silicether monolayer to be an outstanding anode for magnesium-ion batteries (MIBs). The relatively large adsorption energy (1.00 eV) for single Mg atom indicates good structural stability. Silicether could undergo the transition from semiconductor to metal even at a low Mg concentration (0.0625). Furthermore, silicether exhibits the low diffusion barrier (0.21 eV), the maximum storage capacity of 744 mAh g−1, and a suitable open-circuit voltage (0.69–0.84 eV). A slight deformation and volume changes during full intercalation of Mg reveal a favorable cyclability. The above results suggest that silicether could be a promising candidate for MIBs. Silicether as a new anode material for MIBs: fast ion mobility, high storage capacity,and appropriate OCV. [ABSTRACT FROM AUTHOR]

With density functional theory calculations, we systematically studied the adsorption and migration properties of Li/Na/K ions on the β-In2Se3 monolayer to evaluate the performance of β-In2Se3 as an anode material for alkaline-ion batteries. The dynamical and thermal dynamical stability of the β-In2Se3 monolayer is verified by both phonon and ab initio molecular dynamics simulation. The negative adsorption energies of Li, Na, and K ions on the β-In2Se3 monolayer are −1.93, −1.96, and −2.48 eV, respectively, indicating superior ion affinity for Li/Na/K. The predicted specific capacities are 115 mAh/g (Li) and 230 mAh/g (Na/K), and the related volumetric capacities are 698 mAh/cm3 (Li) and 1396 mAh/cm3 (Na/K), respectively. The corresponding energy densities are estimated at 180, 426 and 413 mWh/g for Li/Na/K. Moreover, the ultra-low diffusion barriers for Li/Na/K ions are predicted to be 0.20, 0.14, and 0.09 eV, suggesting a higher ion mobility on the surface of β-In2Se3 monolayer compared to many previously reported anode materials. The above results suggest that β-In2Se3 can be a promising anode material for (Li/Na/K) ion batteries. [ABSTRACT FROM AUTHOR]

In this work, the single Rh atom anchored by N vacancy of C3N monolayer for CO oxidations has been studied by using first-principles calculations. The stability for a single Rh atom in N vacancy of C3N monolayer is detailed investigated. The sizeable binding energy and diffusion barrier of the Rh atom in the N vacancy and the ab initial molecule dynamic simulations at 400 K all verify that the Rh is stable at the N vacancy of the C3N monolayer. We also have examined the bi-molecule Eley–Rideal (ER) and Langmuir–Hinshelwood (LH) and the tri-molecule LH mechanisms on the Rh @ C3N. It is found that the barriers for the rate-limiting step for bi-molecule ER and LH are so significant (1.35, 1.15 eV), while for the tri-molecule LH mechanism, the barrier of the rate-limiting step is only 0.49 eV, which means the tri-molecule LH mechanism is more likely to occur at room temperature on the Rh @ C3N. Thus, our results will shed light on the future design for low-temperature CO oxidation using single-atom catalysts. [ABSTRACT FROM AUTHOR]

Context: In recent years, undivided attention has been given to the unique properties of layered nitrogenated holey graphene (C2N) monolayers (C2NMLs), which have widespread applications (e.g., in catalysis and metal-ion batteries). Nevertheless, the scarcity and impurity of C2NMLs in experiments and the ineffective technique of adsorbing a single atom on the surface of C2NMLs have significantly limited their investigation and thus their development. Within this research study, we proposed a novel model, i.e., atom pair adsorption, to inspect the potential use of a C2NML anode material for KIBs through first-principles (DFT) computations. The maximum theoretical capacity of K ions reached 2397 mA h g−1, which was greater in contrast with that of graphite. The results of Bader charge analysis and charge density difference revealed the creation of channels between K atoms and the C2NML for electron transport, which increased the interactions between them. The fast process of charge and discharge in the battery was due to the metallicity of the complex of C2NML/K ions and because the diffusion barrier of K ions on the C2NML was low. Moreover, the C2NML has the advantages of great cycling stability and low open-circuit voltage (approximately 0.423 V). The current work can provide useful insights into the design of energy storage materials with high efficiency. Methods: In this research, we used B3LYP-D3 functional and 6–31 + G* basis with GAMESS program to calculate adsorption energy, open-circuit voltage, and maximum theoretical capacity of K ions on the C2NML. [ABSTRACT FROM AUTHOR]

Highlights: As an emerging preparation strategy for MXenes, Lewis acidic etching has attracted increasing attention in the past few years benefiting from a series of merits. Lewis acidic etching method is mainly presented from etching mechanism, terminations regulation, in-situ formed metals and delamination of multi-layered MXenes. The applications of MXenes and MXene-based composites obtained by Lewis acidic etching route in energy storage and conversion, sensors and microwave absorption are carefully summarized. Since the discovery in 2011, MXenes have become the rising star in the field of two-dimensional materials. Benefiting from the metallic-level conductivity, large and adjustable gallery spacing, low ion diffusion barrier, rich surface chemistry, superior mechanical strength, MXenes exhibit great application prospects in energy storage and conversion, sensors, optoelectronics, electromagnetic interference shielding and biomedicine. Nevertheless, two issues seriously deteriorate the further development of MXenes. One is the high experimental risk of common preparation methods such as HF etching, and the other is the difficulty in obtaining MXenes with controllable surface groups. Recently, Lewis acidic etching, as a brand-new preparation strategy for MXenes, has attracted intensive attention due to its high safety and the ability to endow MXenes with uniform terminations. However, a comprehensive review of Lewis acidic etching method has not been reported yet. Herein, we first introduce the Lewis acidic etching from the following four aspects: etching mechanism, terminations regulation, in-situ formed metals and delamination of multi-layered MXenes. Further, the applications of MXenes and MXene-based hybrids obtained by Lewis acidic etching route in energy storage and conversion, sensors and microwave absorption are carefully summarized. Finally, some challenges and opportunities of Lewis acidic etching strategy are also presented. [ABSTRACT FROM AUTHOR]

External surface diffusion barriers can be as important as intracrystalline diffusion resistances in affecting zeolite catalysis. This work investigates how SiO2 deposition regulates surface barriers and affects catalytic activities for the zeolites with different pore sizes and dimensionalities (i.e., ZSM-22, ZSM-5, and Beta). n-Pentane isomerization is taken as the model reaction for catalytic tests. After SiO2 deposition, the apparent diffusivities for ZSM-22, ZSM-5, and Beta increase by 5–15%, 31–52%, and 34–37%. SiO2 deposition only modifies crystal surfaces as indicated by various structural characterizations, and thus these improvements in diffusion can be only attributed to the reduced surface barriers. Besides, the apparent catalytic activities for the catalysts using ZSM-22, ZSM-5, and Beta increase by 17–69%, 19–72%, and 3–60%, after SiO2 deposition. These results show that SiO2 deposition should be a universal method to reduce surface barriers on various zeolites and to improve zeolite catalysis for the reaction of n-pentane isomerization. [ABSTRACT FROM AUTHOR]

This article studies various methods for the formation of dielectric diffusion barriers between open areas of copper and an organosilicate low-k dielectric in the subtractive method of forming a metallization system, in which metal lines are first formed, and then a low-k dielectric is deposited. Films of dense and porous organosilicate glass deposited by chemical deposition from solutions are used as a low-k dielectric. A comparison is made between AlN barrier layers formed by atomic layer deposition and SiCN barriers deposited by plasma-assisted chemical vapor deposition. The successful formation of a model structure of copper metallization using AlN barriers is demonstrated. [ABSTRACT FROM AUTHOR]

We describe an indium bump process applicable to our low-temperature detectors and associated readout. A titanium nitride under bump metallization layer is reactively sputtered onto wiring pads as a diffusion barrier and adhesion layer. Indium is thermally evaporated onto this layer at the desired thickness for bump bonding. Patterning for both titanium nitride and indium layers is accomplished by liftoff techniques. The process flow is compatible with many processes utilized for the fabrication of low-temperature detectors and other superconductive devices. [ABSTRACT FROM AUTHOR]

The role of the renal autocoid, nitric oxide (NO), in the mechanism of structural rearrangements in the renal medullary interstitium, affecting the extracellular matrix permeability to water and ions, was studied in WAG rats with a high blood vasopressin (AVP) level and in AVP-deficient Brattleboro rats, both under conditions of experimental hypothyroidism. In WAG rats, the modeling of hypothyroidism led to no significant changes in the renal hydruretic function parameters, while Brattleboro rats, under the same conditions, demonstrated an antidiuretic response due to activation of solute-free water reabsorption. It is assumed that the lack of changes in the parameters of hydruresis in hypothyroid WAG rats is due to an increase in the interstitial content of hyaluronan (HA), a main еxtracellular matrix component of the renal medulla, which forms a diffusion barrier for water and ions. By contrast, in Brattleboro rats, the stimulation of the renal concentrating function in the modeling of hypothyroidism was not accompanied by considerable structural changes in the extracellular matrix, constitutively characterized in this mouse strain by an almost complete lack of HA. It was found that NO plays a significant role in altering the structure of the renal interstitium in WAG rats under conditions of experimental hypothyroidism. NO synthesis blockade with L-NAME abolished the hypothyroidism-induced changes in the extracellular matrix of the renal papilla due to a reduction in the expression level of the hyaluronan synthase 2 (HAS2) gene, encoding the main enzyme of HA synthesis, to the basal (control group) values. The obtained results suggest that hypothyroidism leads to an increase in the HA content in the renal medullary interstitium, with NO playing a key role in this effect. Basal NO activity in the renal papilla depends on the blood AVP level. [ABSTRACT FROM AUTHOR]

The present review systematically analyzed in vitro and in situ studies investigating physical diffusion barriers (sealants, desensitizer or adhesives) to prevent the development or the progression of root (dentin) demineralization. Three electronic databases (PubMed-Medline, CENTRAL, Ovid-EMBASE) were screened for studies from 1946 to 2022. Cross-referencing was used to identify further articles. Article selection and data abstraction were done in duplicate. Languages were not restricted. The type of outcome was not restricted, and their mean differences (MD) were calculated using fixed- or random-effects models. Risk of Bias was graded using Risk of Bias 2.0 tool. From 171 eligible studies, 34 were selected for full-text analysis evaluating 69 different materials, and 17 studies—still evaluating 36 different materials—were included (3 in situ and 14 in vitro). Ten studies evaluated desensitizers; 8 adhesives; and 1 infiltration. Meta-analyses were possible for all 17 studies. Meta-analyses revealed that lesion depth after no treatment was significantly higher than after the application of single-step adhesives (MD[95%CI] = − 49.82[− 69.34; − 30.30]) and multi-step adhesives (MD[95%CI]=–60.09 [–92.65, –27.54]). No significant differences in the lesion depth increase between single- and multi-step adhesives could be observed (MD[95%CI]=30.13 [–21.14, 81.39]). Furthermore, compared to no treatment the increase of the lesion depth was significantly hampered using desensitizers (MD[95%CI] = − 38.02[− 51.74; − 24.31]). Furthermore, the included studies presented unclear or high risk. A physical diffusion barrier can significantly hamper the increase of lesion depth under cariogenic conditions. Furthermore, multi-step adhesives seem not to be more effective than single-step adhesives. However, this conclusion is based on only few in vitro and in situ studies. [ABSTRACT FROM AUTHOR]

Physical and chemical vapor deposition methods are used to apply thermal-barrier coatings (TBCs) to turbine blades. Operations intended to form a diffusion barrier layer constitute an individual process. This increases the coating application time and, accordingly, increases the energy consumption in the production of turbines. In this research, the development of barrier layers at the interface between the substrate blade material and oxidation-resistant metallic layer and at the interface between the oxidation-resistant metallic layer and ceramic layer using a combination of deposition processes was examined. The structure and chemical and phase composition of TBCs at the metal/ceramic interface (NiCrAlY and CoCrAlY alloys/ZrO2–(6–8) wt.% Y2O3 ceramics) deposited in one process cycle were studied. The study focused on the samples cut from blades made of the directionally crystallized ZhS26-VI alloy. The NiCrAlY and CoCrAlY alloys were used for coating the blades. The experiments were performed employing L2 and UE-159 units at the Ivchenko-Progres (Zaporizhzhia) and Eltechmash (Vinnytsia) enterprises. The formation of a diffusion barrier layer at the metal/ceramic interface was examined when the blades preheated to 900 ± 30°C were kept for some time above the ZrO2–(6–8) wt.% Y2O3 ceramic material at 2600 ± ± 50°C. Depending on the holding time, the diffusion barrier layer that developed at the interface between the metallic and ceramic layers significantly differed in morphology and chemical composition from the main TBC layers. The chemical and phase composition of the diffusion barrier layer was determined versus TBC deposition conditions. The results of thermal cycle tests of the coated blades were used to develop coating deposition conditions to promote a diffusion barrier layer with optimal composition and structure. [ABSTRACT FROM AUTHOR]

The formation of CoCu and PtCu alloys on the stepped Cu(111) substrate was simulated. Dendritic and finger-like protrusions grow near the edges of the steps. The shape and the internal structure of the protrusions depend on the type of the step edge, temperature and concentrations of impurity atoms. The internal structure and the shape of the protrusions are significantly different in PtCu and CoCu alloys. Pt atoms tend to be surrounded by Cu atoms and Co atoms tend to combine into Co backbones. The dendritic protrusions usually grow at 200 K and the finger-like protrusions usually grow at 300 K. The shape of the protrusions also depends on the type of the step edge and the concentration of impurity atoms. The main differences of PtCu and CoCu protrusions can be explained by the values of the diffusion barriers of the key processes. [ABSTRACT FROM AUTHOR]

With recent rapid increases in Cu resistivity, RC delay has become an important issue again. Co, which has a low electron mean free path, is being studied as beyond Cu metal and is expected to minimize this increase in resistivity. However, extrinsic time-dependent dielectric breakdown has been reported for Co interconnects. Therefore, it is necessary to apply a diffusion barrier, such as the Ta/TaN system, to increase interconnect lifetimes. In addition, an ultrathin diffusion barrier should be formed to occupy as little area as possible. This study provides a thermodynamic design for a self-forming barrier that provides reliability with Co interconnects. Since Cr, Mn, Sn, and Zn dopants exhibited surface diffusion or interfacial stable phases, the model constituted an effective alloy design. In the Co-Cr alloy, Cr diffused into the dielectric interface and reacted with oxygen to provide a self-forming diffusion barrier comprising Cr2O3. In a breakdown voltage test, the Co-Cr alloy showed a breakdown voltage more than 200% higher than that of pure Co. The 1.2 nm ultrathin Cr2O3 self-forming barrier will replace the current bilayer barrier system and contribute greatly to lowering the RC delay. It will realize high-performance Co interconnects with robust reliability in the future. [ABSTRACT FROM AUTHOR]

The electrochemical performance of double transition metal MoWC MXene has been examined by employing first principles approach for its popular usage as an efficient anode material in Li-ion batteries. The thermodynamic stability is determined using ab-initio molecular dynamics, geometry optimization and phonon dispersion calculations. The electronic structural calculations reveal that the MoWC monolayer exhibits high electronic conduction. Further, the low diffusion barrier of 0.040 eV on W-layer side and 0.029 eV on Mo-layer side of MoWC monolayer have been observed in present study. Moreover, the charge storage capacity of 670 mAh g−1 is predicted for the respective material, which indicates its better electrochemical performance as compared to their single metal carbides Mo2C and W2C MXenes. Also, the low average working voltage (~ 0.44 V) of MoWC MXene suggests its application as a potential candidate for anode material in Li-ion batteries. [ABSTRACT FROM AUTHOR]

First-principles calculations based on density functional theory were used to investigate the electrochemical performance of monolayer γ-PC for Na- and K-ion batteries. Molecular dynamics simulations indicate that the monolayer γ-PC have the thermal and dynamic stability. A substantial charge transfer from the Na/K atoms to the γ-PC sheet enhances the electrical conductivity of γ-PC. The results show that the adsorption energies of Na and K are 1.53 eV and 2.04 eV, respectively, which are much higher than Na/K bulk cohesive energy and sufficiently ensure stability and safety. Additionally, the low diffusion barriers on γ-PC monolayer are 0.034 eV for Na and 0.027 eV for K, indicating excellent rate performance. The γ-PC sheet has a high theoretical capacity for both Na (519.9 mAh/g) and K (326.6 mAh/g) ion batteries, which can satisfy the requirement of energy storage devices to anode materials. Our results strongly suggest that 2D γ-PC monolayer is an exceedingly promising anode material for both NIBs and KIBs with high adsorption energies, high capacity, and low diffusion barriers. [ABSTRACT FROM AUTHOR]

The perineurium serves as a selective, metabolically active diffusion barrier in the peripheral nervous system, which is composed of perineurial cells joined together by tight junctions (TJs). Not only are these junctions known to play an essential role in maintaining cellular polarity and tissue integrity, but also limit the paracellular diffusion of certain molecules and ions, whereas loss of TJs barrier function is imperative for tumour growth, invasion and metastasis. Hence, a detailed study on the barrier function of perineurial cells may provide insights into the molecular mechanism of perineural invasion (PNI). In this study, we aimed to develop an efficient procedure for the establishment of perineurial cell lines as a tool for investigating the physiology and pathophysiology of the peripheral nerve barriers. Herein, the isolation, expansion, characterization and maintenance of perineurial cell lines under favourable conditions are presented. Furthermore, the analysis of the phenotypic features of these perineurial cells as well as the barrier function for the study of PNI are described. Such techniques may provide a valuable means for the functional and molecular investigation of perineurial cells, and in particular may elucidate the pathogenesis and progression of PNI, and other peripheral nerve disorders. [ABSTRACT FROM AUTHOR]

The effect of Co, Pd and Pt ultrathin films on the kinetics of the formation of Ni-silicide by reactive diffusion is investigated. 50 nm Ni/1 nm X/ 50 nm Ni (X = Co, Pd, Pt) deposited on Si(100) substrates are studied using in-situ and ex-situ measurements by X-ray diffraction (XRD). The presence of Co, Pd or Pt thin films in between the Ni layers delays the formation of the metal rich phase compared to the pure Ni/Si system and thus these films act as diffusion barriers. A simultaneous silicide formation (δ-Ni2Si and NiSi phases) different from the classic sequential formation is found during the consumption of the top Ni layer for which Ni has to diffuse through the barrier. A model for the simultaneous growth in the presence of a barrier is developed, and simulation of the kinetics measured by XRD is used to determine the permeability of the different barriers. Atom probe tomography (APT) of the Ni/Pd/Ni system shows that the Pd layer is located between the Ni top layer and δ-Ni2Si during the silicide growth, in accordance with a silicide formation controlled by Ni diffusion through the Pd layer. The effect of the barrier on the silicide formation and properties is discussed. [ABSTRACT FROM AUTHOR]

Hydrogen embrittlement (HE) of advanced high-strength steels is a crucial problem in the automotive industry, which may cause time-delayed failure of car body components. Practical approaches for evaluating the HE risk are often partially and contradictive in nature, because of hydrogen desorption during testing and inhomogenous hydrogen distributions in, e.g., notched samples. Therefore, the present work aims to provide fully parametrized and validated bulk diffusion models for three dual phase steels to simulate long-range chemical diffusion, trapping and hydrogen desorption from the surface. With one constant set of parameters, the models are able to predict the temperature dependency of measured Choo-Lee plots as well as the concentration dependency of measured effective diffusion coefficients. Finally, the parametrized and validated bulk diffusion models are applied for studying the role of the current density on the permeation time and the role of coatings as effective diffusion barriers. [ABSTRACT FROM AUTHOR]

Composite Ti3SiC2/TiC MAX-phase coating was obtained by the detonation spraying onto U9 steel substrate using the mixed powder in the molar ratio of 74Ti/20SiC/6C as raw material. At the as-sprayed state, the synthesized composite had a stable double-phase composition: the main TiC phase and secondary Ti3SiC2 MAX-phase. After thermal annealing at 700, 800 and 900 °C, oxidation occurred in the coatings, as indicated by the appearance of high-temperature-stable anatase TiO2 phase at the diffraction patterns. It was found that annealed at 800 °C coating demonstrated the best structural, compositional, tribo-mechanical and corrosion resistance characteristics. In particular, hardness increased to 1400 ± 75HV0.2, coefficient of friction decreased to 0.35, adhesion strength was 14 N, and corrosion potential was 1.88 × 10−2 A/cm2. The corrosion potential of the annealed composite was 5.5 times less than that of the steel substrate, which indicates its strong corrosion protection. The relatively higher density, the formation of the main TiC phase that inhibits the grain growth and TiO2 thin surface layer that serves as good diffusion barriers were the main reasons for the improvement of the functional parameters. [ABSTRACT FROM AUTHOR]

Co-based alloys have received extensive attention as barrier layers of Sn/Cu joints in the microelectronic packaging. However, little attention has been paid to the combine effect of alloy content and grain size on the diffusion barrier performance. In this work, the 150 °C solid-state interfacial reactions of Sn/Co and Sn/Co-W with different W contents were investigated. Besides crystalline Co-Sn intermetallic compounds (IMCs), amorphous Co0.36Sn0.64 and amorphous Co-W-Sn IMCs formed at Sn/Co and Sn/Co-W interfaces, respectively. The IMCs growth kinetics of Sn/Co interface was reaction-controlled. Meanwhile, that of Sn/Co-W interface was diffusion-controlled, due to the diffusion barrier of the amorphous Co-W-Sn. The decreased grain size of Co-10 at%W made larger contribution to the Co diffusion; thus, the IMCs growth rate of Sn/Co-10 at%W was faster than Sn/Co-5 at%W interface. While those of Sn/Co-15 at%W and Sn/Co-20 at%W interfaces dramatically slowed down, due to the increased pinning effect of W atoms and amorphous structure of Co-W. This research can contribute to providing insights into the reliability of electronic packaging. [ABSTRACT FROM AUTHOR]

Highlights: We propose a novel synthetic strategy for converting MXene nanosheets into 3D balls coated with iron selenides and carbon (FeSex@C/MB), using the ultrasonic spray pyrolysis and thermal treatment. Combining iron selenides and carbon with 3D MXene balls offer many more sites for ion storage and enhance the structural robustness of the composite balls. The resultant shows high electrochemical performances when used in potassium-ion battery in terms of cycling stability and rate capability. Two-dimensional (2D) MXenes are promising as electrode materials for energy storage, owing to their high electronic conductivity and low diffusion barrier. Unfortunately, similar to most 2D materials, MXene nanosheets easily restack during the electrode preparation, which degrades the electrochemical performance of MXene-based materials. A novel synthetic strategy is proposed for converting MXene into restacking-inhibited three-dimensional (3D) balls coated with iron selenides and carbon. This strategy involves the preparation of Fe2O3@carbon/MXene microspheres via a facile ultrasonic spray pyrolysis and subsequent selenization process. Such 3D structuring effectively prevents interlayer restacking, increases the surface area, and accelerates ion transport, while maintaining the attractive properties of MXene. Furthermore, combining iron selenides and carbon with 3D MXene balls offers many more sites for ion storage and enhances the structural robustness of the composite balls. The resultant 3D structured microspheres exhibit a high reversible capacity of 410 mAh g−1 after 200 cycles at 0.1 A g−1 in potassium-ion batteries, corresponding to the capacity retention of 97% as calculated based on 100 cycles. Even at a high current density of 5.0 A g−1, the composite exhibits a discharge capacity of 169 mAh g−1. [ABSTRACT FROM AUTHOR]

The Mg adsorption and diffusion behaviors on nitrogen-doped (N-doped) Mo2C monolayer have been investigated by the first principles based on density functional theory (DFT). To investigate the effect of nitrogen concentration on adsorption energies, Mo2C1−xNx (x=0.0625, 0.125, 0.1875, and 0.25) with four different nitrogen doping concentrations have been considered in the present work. The results show that N-doped Mo2C is benefit for Mg adsorption. In particular, when the doping concentration reaches to 14.29%, the adsorption energies of Mg on Mo2C0.875N0.125 are in the region between −1.639 and −1.517 eV, e.g., the adsorption energies of Mg on TC1 and H2 sites are −1.639 eV and −1.625 eV, which are decreased by 16.49% and 18.43% as compared with the pristine Mo2C. The calculations on diffusion behaviors show that the Mg diffusing between two adjacent favored sites via a high-symmetry site along H3-B-H4 and H1-B-H1 paths possesses the barriers of 0.021 eV and 0.028 eV. Additionally, the partial density of states (PDOS) reveals the interaction between Mg and Mo2C0.875N0.125, and indicates that nitrogen doping causes the PDOS peaks transfer to a lower energy level, which is benefit for the bonding between Mg and Mo2C0.875N0.125. These results suggest that the adsorption and diffusion behaviors of Mg have been enhanced by nitrogen doping. [ABSTRACT FROM AUTHOR]

Improving the storage capacities of electrode materials is one of the most critical points for ion batteries. Two-dimensional (2D) topological semimetals with high carrier mobility are naturally suitable as electrode materials. Herein, using the first-principle calculations, 2D BP monolayer with Dirac-type band structure is predicted to be a superior anode material with ultrahigh capacity for both Li/Na-ion batteries. The BP monolayer remains metallic after the adsorption of Li/Na ions, ensuring a good conductivity. Furthermore, BP owns low diffusion barriers (0.35 eV for Li ions and 0.16 eV for Na ions) and a moderate lattice change (3%) during the process of charging and discharging. Remarkably, the storage capacity of monolayer BP is enhanced to 1924 mAh/g by multilayer adsorption of both Li/Na ions, much higher than those of most previous 2D anode materials. All these characteristics strongly suggest that BP has great potential as a superior anode material in Li/Na-ion batteries. [ABSTRACT FROM AUTHOR]

Synthetic antiferromagnets (SAFs), composed of Ru spacer with a Re insertion layer, reveal superior thermal stability up to 450 °C annealing, making the back-end of line process a wider manufacturing window and tolerance to integrate the perpendicular magnetic tunneling junctions (P-MTJs) into CMOS process. The coupling strength decays significantly for SAFs with single Ru spacer after annealing above 400 °C. Due to the characteristics of refractory metals, Re can behave as a diffusion barrier during annealing. Furthermore, the Re spacer can still keep reasonable RKKY coupling strength. Therefore, the SAFs with Ru/Re composite spacers exhibit higher RKKY coupling strength than Ru spacers after 450 °C annealing. In addition, we discovered the different enhancements for the upper and lower interfacial Re insertion, which was attributed to the varied defect formation at interfaces. The stacking fault was formed at the upper Ru/Co interface in as-deposited state. When Re was inserted at the upper interface, the diffusion between Co and Ru was significantly suppressed and the stacking fault can be eliminated during annealing, leading to enhanced interlayer coupling. Through the interfacial engineering, we may have more degrees of freedom to tune the SAF performance and thus enhance process compatibility of P-MTJ to the CMOS process. [ABSTRACT FROM AUTHOR]

Herein we present a computational study on the characteristics of two potassium-ion based anode systems for energy storage applications. Different phases of K–Sn and K–P systems have been examined, and those that can be formed in a secondary battery are further characterized. The characterization includes mechanical properties, such as bulk modulus, and electronic properties, such as band structure and chemical shielding. The voltage profile of the anode during charging, the diffusion barrier of ions in fully charged phases, and X-ray diffraction were investigated using a density functional theory approach. The density of states and band-gap of the thermodynamically feasible systems are calculated. The simulation results suggest that both systems perform in a range that is acceptable for use in energy storage applications. It is noted that, while a higher capacity can be achieved for the K–P system, K–Sn would lead to a better discharge rate. This suggests that a composite of these two systems can have real applications. Comparing mechanical properties with the evolution of total charge from the atoms gives insight into the physics underlying these mechanical properties. The simulation results may help the experimentalists better characterize the electrochemistry of the charge and discharge processes in K–Sn and K–P batteries. [ABSTRACT FROM AUTHOR]

Chemical solution deposition technique has been utilized to grow polycrystalline PZT thick films on Pt/Ti/SiO2/Si and TiO2-buffered Pt/Ti/SiO2/Si substrates. Effect of thin TiO2 buffer layer on the structural, dielectric and electrical properties of PZT films has been investigated in the present work. Polycrystalline single-phase PZT thick film is achieved using the buffer layer of TiO2. The disappearance of cracks in PZT films deposited on TiO2/Pt/Ti/SiO2/Si substrate indicates the role of the buffer layer as a diffusion barrier for platinum into PZT. The dielectric constant of the PZT film is found to be increased from 104 to 403, while the dielectric loss is reduced from 0.19 to 0.06 at 1MHz using the buffer layer of TiO2. Reduction in the leakage current density from 4.45×10−5 to 2.42×10−10 A/cm2 is obtained for the titanium dioxide buffer layered PZT film. The saturation polarization (Ps = 45 μC/cm2) is achieved for the optimized TiO2-buffered PZT thick film. Optimized PZT film shows well-defined butterfly loop revealing its ferroelectric nature. Free carrier concentration of the optimized film is determined from the Mott Schottky analysis and found to be 4.28×1019 cm−3. The ferroelectric photovoltaic device is fabricated using the optimized PZT thick film, and photovoltaic measurements are done under UV illumination with variation in UV intensity from 2 to 24 mW/cm2. Short circuit current (Isc) increased from 1.42 × 10−9 to 0.63 × 10−7 A with increase in the UV intensity from 2 to 24 mW/cm2. However, open circuit voltage (−1.7V) is observed to remain constant with increase in the UV intensity 2 mW/cm2 to 24 mW/cm2, respectively. The power conversion efficiency is found to be increased from 0.15 to 0.58% with increase in the UV intensity from 2 to 24 mW/cm2. The transient photocurrent is increased from 1.80 × 10−9 to 1.57×10−7 A with increase in the UV intensity from 2 to 24 mW/cm2 at fixed DC bias voltage (5V) for the fabricated photovoltaic device. Response of the optimized fabricated photovoltaic cell to the incident UV light of different intensities is fast with excellent stability. A significant enhancement in the photocurrent from 1.68×10−7 to 4.98×10−7 A is found with heating along with UV illumination (intensity =24 mW/cm2). [ABSTRACT FROM AUTHOR]

Olivine-structure LiFePO4 is considered as promising cathode materials for lithium-ion batteries. However, the material always sustains poor electron conductivity and restricted lithium-ion diffusion channel, severely hindering its further commercial application. In this work, adjusting the synthesis condition on pH value is a practical approach to reduce the nanoparticle size, which vastly boosts its performance. The pH = 6 sample exhibits the highest specific capacity (149.7 mAh/g at 0.1 C) and capacity retention (96.3% after 50 cycles at 0.1 C, 89.7% after 200 cycles at 1 C) among the other LiFePO4/C powders. Compared to pH = 8 electrode, cyclic voltammetry and electrochemical impedance analysis disclose the reduced charge transfer resistance from 1492 to 993 Ω. Lithium-ion diffusion coefficient from 1.13 × 10–14 to 4.24 × 10–14 cm2s−1suggests that the optimal pH value can effectively minimize particle size, improve contact area, and buffer the diffusion barrier, including electron and ion, thus including the electrochemical property. Our study provides a simple and efficient strategy to design and optimize promising olivine-structural cathodes for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

High temperature oxidation of Ni–18Fe–19Cr alloys with different Nb contents (based on the chemical composition of Alloy718) was investigated to elucidate the effect of Nb on oxidation kinetics and scale formation after exposure at 800 °C in air. The experimental results indicated that the oxidation kinetics decreased with increasing niobium content. Rapid establishment of an external Cr2O3 scale was interpreted by the formation of a continuous CrNbO4 layer at the metal-oxide interface, which acts as a diffusion barrier for inward oxygen and outward Fe and Ni diffusion and is of benefit for the establishment of an external Cr2O3 scale. The early establishment of this diffusion barrier prevented internal oxidation of chromium and reduced the growth of the outer Ni2FeO4 oxide scale. The beneficial effect of Nb could be attributed to effectively increasing the volume fraction of internal oxide precipitates, which are favorable for rapid establishment of an external Cr2O3 scale. [ABSTRACT FROM AUTHOR]

Concentrating solar power plant designers are interested in supercritical CO2 (sCO2) for the power block to achieve > 50% electrical efficiency at > 700 °C. The goal of this project was to develop a long-term (> 100 kh) lifetime model for sCO2 compatibility using 10–15 kh laboratory exposures. Three Ni-based alloys (625, 282 and 740H) and an advanced austenitic stainless steel were evaluated in long-term exposures at 700–800 °C using 500-h cycles in laboratory air, 0.1 MPa industrial grade (IG) CO2 and 30 MPa supercritical IG CO2 and using 10-h cycles in 0.1 MPa IG CO2 and O2. Mass change data and quantification of the oxide scale thickness and depth of internal attack after 1000–10,000 h exposures at 750 °C indicate that these materials are compatible with the sCO2 environments with modeling used to predict long-term behavior. Comparison of the 0.1 and 30 MPa 500-h cycle results did not show a significant effect of pressure on the reaction, and no significant internal carburization was observed under these conditions, even for the stainless steel, suggesting that chromia scales may be better C diffusion barriers than expected. For the Ni-based alloys, thermal cycling to simulate the solar duty cycle did not result in scale spallation after 15 kh in 10-h cycles or 4 kh in 1-h cycles at 750 °C. However, the stainless steel specimens formed an Fe-rich oxide after ~ 1500-h cumulative exposure time in both 1- and 10-h cycles. [ABSTRACT FROM AUTHOR]

It is shown that in orthorhombic TaS3 with quenching defects, when the temperature changes in the region below the Peierls transition temperature T < TP, forced diffusion of defects arises due to their strong interaction with the charge density wave (CDW). The relationships between the concentration of quenching defects, n, the threshold field of the onset of CDW sliding, ET, and the defect-induced shift of TP are determined: ET ∝ n and ΔTP ∝ n. This set of laws corresponds to the case when quenching defects positions are correlated with the CDW. The ordinary (without thermocycling) diffusion of quenching defects was detected at T ≈ 300 K, its diffusion coefficient and the height of the energy barrier were estimated. This made it possible to clarify the most probable nature of the defects. These are interstitial sulfur impurities introduced during quenching into the van der Waals gap between the chains and partially ordered at T < TP due to interaction with the CDW. This ordering significantly lowers the height of the energy barrier of forced diffusion in comparison with ordinary diffusion when the spatial configuration of the CDW changes during thermocycling. This leads to the appearance of anomalously high low-temperature forced mobility of correlated impurities. [ABSTRACT FROM AUTHOR]

The adsorption behavior of single CO molecules at 4 K bound to Au adatoms on a Ag(001) metal surface is studied with scanning tunneling microscopy (STM) and inelastic electron tunneling spectroscopy (IETS). In contrast to earlier observations two different binding configurations are observed—one on top of a Au adatom and the other one adsorbed laterally to Au on Ag(001). Moreover, IETS reveals different low-energy vibrational energies for the two binding sites as compared to the one for a single CO molecule bound to Ag(001). Density functional theory (DFT) calculations of the adsorption energies, the diffusion barriers, and the vibrational frequencies of the CO molecule on the different binding sites rationalize the experimental findings. [ABSTRACT FROM AUTHOR]

Film structures composed of several identical modules [Co(x)/a-Si(100)/Cu(70)], where the x value varies from 2 to 10 nm, are investigated as an anode material for liquid lithium-ion batteries. It is shown that relatively thick cobalt layers are effective diffusion barriers for silicon and copper atoms, as well as for lithium ions. This leads to a decrease in the capacitance characteristics of the films under study. Thin cobalt layers (less than 3 nm) with a network structure, on the contrary, increase the capacitance characteristics of the anode films. This is caused by more uniform distribution of lithium ion drift channels that are formed at the initial stage of electrochemical cycling of electrodes over their volume. [ABSTRACT FROM AUTHOR]

It is shown that in orthorhombic TaS3 with quenching defects, when the temperature changes in the region below the Peierls transition temperature T < TP, forced diffusion of defects arises due to their strong interaction with the charge density wave (CDW). The relationships between the concentration of quenching defects, n, the threshold field of the onset of CDW sliding, ET, and the defect-induced shift of TP are determined: ET ∝ n and ΔTP ∝ n. This set of laws corresponds to the case when quenching defects positions are correlated with the CDW. The ordinary (without thermocycling) diffusion of quenching defects was detected at T ≈ 300 K, its diffusion coefficient and the height of the energy barrier were estimated. This made it possible to clarify the most probable nature of the defects. These are interstitial sulfur impurities introduced during quenching into the van der Waals gap between the chains and partially ordered at T < TP due to interaction with the CDW. This ordering significantly lowers the height of the energy barrier of forced diffusion in comparison with ordinary diffusion when the spatial configuration of the CDW changes during thermocycling. This leads to the appearance of anomalously high low-temperature forced mobility of correlated impurities. [ABSTRACT FROM AUTHOR]