Transition Interface Research Articles

Bifunctional modulation of Li-rich layered oxide cathode material via W-modification for improved electrochemical performance

Lithium-rich layered oxides (LRLOs) have raised the greatest attention to the high-energy-density Li-ion batteries. Nevertheless, the undesirable interfacial side reactions and the structure transformation cause fast voltage fading and poor capacity retention of LRLO cathodes, which extremely prevent their practical application. Surface coating or lattice doping has been an effective strategy to improve its electrochemical properties. However, the general performance of the material can only be limitedly promoted. Herein, we proposed a bifunctional modulation of LRLO cathodes coupled by bulk-phase W-doping and surficial Li2WO4 nanocoating of LRLOs using a facile synchronous lithiation strategy under a high-temperature solid-state treatment. The modified material (2 mol% W6+ modified) showed a distinguished discharge capability of 260.5 mAh/g at 0.1 C after 50 cycles. Meanwhile, a competitive capacity retention of 95.38% at 1 C after 100 cycles was achieved. The splendid electrochemical performance can be the result of the increased interlayer spacing for enhancing Li+ diffusion kinetics and the stronger W–O bond for alleviating oxygen release after W-doping and Li2WO4 nanocoating, which not only accelerates the Li+ transfer rate as its fast Li+ transfer channels but also act as a transitional interface layer to restrain the interfacial adverse reactions.

Ion migration at the ice–water interface during the freezing process of salt solution – Experimental investigation

Within the scope of this work, systematic investigations of the ion migration process at the ice–water interface during the freezing of salt solutions are performed via experimental investigations (part I) and numerical investigations (part II). In this study, the ion migration trend under different freezing temperatures was revealed, and the formation process of the brine pockets during phase transition and the mechanism of ion release in ice were explored. The results show that the migration capabilities of Na+ and K+ are greater than those of Ca2+ and Mg2+, whereas the migration capability of Cl− is greater than those of HCO3− and SO42−. At −2 °C, the ion concentration in the surface ice decreased by 47.64 %, indicating the occurrence of ion release within the ice. When the moving speed of the phase transition interface is greater than the ion diffusion ability, the brine pockets form in the ice. Under a temperature gradient, the brine pockets in ice become thermodynamically unstable, resulting in the inevitable ion release toward the high-temperature side. The ion release depends on the temperature gradient and the brine pocket concentration. Furthermore, the unsynchronous migration of ions is related to the freezing temperature, diffusion coefficient, hydration radius, and hydration free energy.

Energy redistribution in railway transition zones by geometric optimisation of a novel transition structure

Railway transition zones are critical regions in railway infrastructure that are subjected to excessive operation-driven degradation due to energy concentration within these zones. This work presents a heuristic approach to optimise the geometry of the transition structure and investigate its influence on the strain energy distribution in the railway transition zones (RTZs), with a specific focus on embankment-bridge transitions equipped with a newly proposed ’Safe Hull-Inspired Energy Limiting Design (SHIELD)’ transition structure. For this purpose, a number of three-dimensional finite element models are used to analyze different geometric profiles of SHIELD in a systematic manner. By altering SHIELD’s geometry across longitudinal, transversal, and vertical directions, the influence of the different geometric profiles on the total strain energy distribution across the trackbed layers (ballast, embankment, and subgrade) is studied in terms of spatial and temporal variations. The results establish the contribution of geometry to energy redistribution in all three directions and present an optimum geometry for the type of transition under study. It is found that among all the profiles, the longitudinal geometric profile of SHIELD has the most significant impact on the strain energy distribution, while the transversal profile primarily influences the ballast layer, and the alteration of vertical profiles enhance the local redistribution of strain energy in the vicinity of the transition interface. The preliminary optimisation (heuristic approach) presented in this work provides the starting point for full-scale optimisation to obtain tailored shapes of transition structures such that there is neither a concentration of energy nor an obstruction in the flow of energy in RTZs.

Multiphase growth and basin control of main faults on Northern sub-basin, Beibuwan basin, Northwestern South China sea

The basement-involved faults and multiphase extension control the three-dimensional (3-D) fault geometries and kinematics, producing different fault growth models in continental rift basins. In this paper, we apply qualitative and quantitative fault analysis techniques to 3D high-resolution seismic data from the Northern sub-basin of Beibuwan basin, building the tectonic-stratigraphic framework and proposing the evolutionary meachanisms of main normal faults. The results suggest that extensional stress changed from NW-SE direction during Paleocene-Middle Eocene to N-S direction in Late Eocene-Oligocene, leading to the ENE or E-W directed propagation of fault networks together with lateral and vertical linkage of fault segments. This includes three conceptual models: (1) F1 originated from propagation, interaction, linkage and failure of initial seven ENE-directed isolated faults, and grows following isolated fault growth model; (2) F2 nucleated as a normal fault before buried in Late Eocene, and reactivated as dextral strike-slip fault in Oligocene, therefore experienced vertical segmentation and linkage; (3) F3 activated as a long-term constant-length fault with generally increased displacement in Paleogene. Our study proposes that the T83 interface (the top of the second member of the Liushagang Formation) is a tectonic stress transition interface, while the T60 interface is both a tectonic inversion interface and a post-rift unconformity interface. Furthermore, the growth of extensional faults commonly accompanied single breached, transfer-fault breached or double breached relay ramps and fault-related folds, thereby exerting a significant influence on the basin architecture and sediment distribution.

The thermodynamic effects of solute on void nucleation in Mg alloys.

Replica exchange transition interface sampling simulations in Mg-Al alloys with high vacancy concentrations indicate that the presence of a solute reduces thermodynamic barriers to the clustering of vacancies and the formation of voids. The emergence of local minima in the free energy along the reaction coordinate suggests that void formation may become a multi-step process in the presence of a solute. In this scenario, vacancies agglomerate with solute before they coalesce into a stable void with well-defined internal surfaces. The emergence of vacancy-solute clusters as intermediate states would imply that classical nucleation theory is unlikely to adequately describe void formation in alloys at high vacancy concentrations, a likely precursor for alloy strengthening through nanoscale precipitation.

Fucoidan Cross‐Linking Polyacrylamide as Multifunctional Aqueous Binder Stabilizes LiCoO2 to 4.6 V

AbstractRaising the cutoff voltage can efficiently increase the energy density of lithium cobalt oxide (LCO). However, upon charging over 4.55 V the LCO undergoes irreversible phase transition from the pristine O3 phase to the metastable H1‐3 phases, causing serious side reactions, which results in poor cycling stability. Herein, a multifunctional aqueous composite binder derived from the cross‐linking of fucoidan (FUC) and polyacrylamide (PAM) is developed to enhance the stability of LCO cathode at 4.6 V. The cross‐linking interaction of FUC and PAM provides a uniform coating on the surface of LCO and ensures a high peel strength for the electrode, effectively mitigating irreversible phase transition and detrimental interface side reactions. More importantly, the sulfur ester and amide groups of FUC‐PAM favorably function as surface charge compensators to the high valent Co upon charging under high voltages, thus stabilizes the surface lattice of LCO and suppresses the detrimental oxygen release. As expected, the LCO with a cutoff voltage of 4.6 V exhibits a high capacity retention of 90% after 100 cycles at a current density of 110 mA g−1. The interfacial coordination effect of composite binders offers a novel strategy to enhance the stability of high‐voltage LCO for high‐energy lithium‐ion batteries.

The rigid-flexible balanced molecular crosslinking network transition interface: An effective strategy for improving the performance of bamboo fibers/poly(butadiene succinate-co-butadiene adipate) biocomposites

The poor interfacial compatibility of natural fiber-reinforced polymer composites has become a major challenge in the development of industry-standard high-performance composites. To solve this problem, this study constructs a novel rigid-flexible balanced molecular crosslinked network transition interface in composites. The interface improves the interfacial compatibility of the composites by balancing the stiffness and strength of the fibers and the matrix， effectively improving the properties of the composites. The flexural strength and flexural modulus of the composites were enhanced by 38 % and 44 %, respectively. Water absorption decreased by 30 %. The initial and maximum thermal degradation temperatures increased by 20 °C and 16 °C, respectively. The maximum storage modulus increased by 316 %. Furthermore, the impact toughness was elevated by 41 %, attributed to the crosslinked network's efficacy in absorbing and dissipating externally applied energy. This innovative approach introduces a new theory of interfacial reinforcement compatibility, advancing the development of high-performance and sustainable biocomposites.

On Klein tunneling of low-frequency elastic waves in hexagonal topological plates

Incident particles in the Klein tunnel phenomenon in quantum mechanics can pass a very high potential barrier. Introducing the concept of tunneling into the analysis of phononic crystals can broaden the application prospects. In this study, the structure of the unit cell is designed, and the low frequency (< 1 kHz) valley locked waveguide is realized through the creation of a phononic crystal plate with a topological phase transition interface. The defect immunity of the topological waveguide is verified, that is, the wave can propagate along the original path in the cases of impurities and disorder. Then, the tunneling phenomenon is introduced into the topological valley-locked waveguide to analyze the wave propagation, and its potential applications (such as signal separators and logic gates) are further explored by designing phononic crystal plates. This research has broad application prospects in information processing and vibration control, and potential applications in other directions are also worth exploring.

Heat transfer efficiency of thermoelastic shaped phase change materials enhanced by pressure

As the melt front gradually moves away from the heat source during the heat transfer process, phase change materials (PCMs) inevitably cause the heat transfer efficiency to decrease with heat transfer time, especially for a shaped PCM (SPCM). In this study, it is proposed to compress the SPCM phase-changed region by pressure to reduce the thermal resistance between the heat source and the phase transition interface, thus slowing down the rate of heat transfer efficiency decrease. We established a one-dimensional semi-infinite compression heat transfer theoretical model and prepared a thermoelastic SPCM (TESPCM) for compression heat transfer experiments, which verified the reliability of the theoretical model. Experimental demonstrate that the pressure enhancement contributes to the heat transfer efficiency and becomes more pronounced with heat transfer time. The pressure-enhanced heat transfer was analyzed by the theoretical model with the following conclusions: pressure enhancement not only improves the latent heat utilization, heat transfer cut-off time, and maximum tolerable heat flux of TESPCM but also increases the specific energy and specific power of TESPCM. The effect of pressure on heat transfer efficiency tends to accelerate with increasing compression. Furthermore, the improvement of heat transfer by pressure enhancement becomes more significant with the increase of thermal conductivity, but the effect of latent heat on temperature control decreases with the increase of compression.

Development and Usability Evaluation of Transitional Cross-Reality Interfaces

The concept of Transitional Cross-Reality Interfaces where a user can seamlessly transition across the Reality-Virtuality-Continuum dates back to the introduction of the Magic Book in 2001 but recently gained new research momentum since head-mounted displays advanced by combining the former distinctive concepts of augmented reality and virtual reality into a single device. New technological capabilities require new ways of developing applications to satisfy user requirements. Especially in the context of operating in multiple realities, developing AR/VR applications is not a trivial task. In this context, the development of Transitional Cross-Reality Interfaces remains a complex engineering problem that requires specific methods, concepts, and tools. To address this problem and provide a systematic development approach, we propose a conceptual framework for both developing and evaluating Transitional Cross-Reality Interfaces. To evaluate our solution, we implemented a Transitional Cross-Reality Interface based on our framework and evaluated it with both the measurements provided by the framework and additional questionnaires. We found high usability and interesting transitional behavior of users indicating the usefulness of the proposed framework as an underlying software architecture for Transitional Cross-Reality Interfaces.

Cooperative enhancement of mechanical and tribological properties through tailoring TiN transition interface in boron nitride nanosheets reinforced copper composites

Cooperative enhancement of mechanical and tribological properties through tailoring TiN transition interface in boron nitride nanosheets reinforced copper composites

Cu-N Synergism Regulation to Enhance Anionic Redox Reversibility and Activity of Li- and Mn-Rich Layered Oxides Cathode.

Anionic redox chemistry enables extraordinary capacity for Li- and Mn-rich layered oxides (LMROs) cathodes. Unfortunately, irreversible surface oxygen evolution evokes the pernicious phase transition, structural deterioration, and severe electrode-electrolyte interface side reaction with element dissolution, resulting in fast capacity and voltage fading of LMROs during cycling and hindering its commercialization. Herein, a redox couple strategy is proposed by utilizing copper phthalocyanine (CuPc) to address the irreversibility of anionic redox. The Cu-N synergistic effect of CuPc could not only inhibit surface oxygen evolution by reducing the peroxide ion O2 2- back to lattice oxygen O2-, but also enhance the reaction activity and reversibility of anionic redox in bulk to achieve a higher capacity and cycling stability. Moreover, the CuPc strategy suppresses the interface side reaction and induces the forming of a uniform and robust LiF-rich cathode electrolyte, interphase (CEI) to significantly eliminate transition metal dissolution. As a result, the CuPc-enhanced LMRO cathode shows superb cycling performance with a capacity retention of 95.0% after 500 long-term cycles. This study sheds light on the great effect of N-based redox couple to regulate anionic redox behavior and promote the development of high energy density and high stability LMROs cathode.

Exploring the Relationship between the Dynamics of the Urban–Rural Interface and Regional Development in a Post-Socialist Transition

This study offers, by an empirical analysis, another perspective on post-socialist development, highlighting the role of the urban–rural interface in regional dynamics. The current literature on the relationships between both issues is not too rich and our paper analyzes the relationships between core cities, their peri-urban areas, and their regions, through a comparative overview of their growth over the last three decades. Romania, as a special case study for a contradictory transition, due to the great step from a drastic dictatorial regime to a democracy and a market economy, is a good example to test these complex relationships. Considering the new development trend at the urban–rural interfaces, our key idea was to depict their contribution to regional development (NUTS 3) compared to city cores. The second question was how this differentiated contribution can be measured, using the simplest tool. The starting point was the fact that population dynamics reflect all changes in the city core and at the urban–rural interface, and less so at a regional level. Consequently, we selected the dynamics of the number of inhabitants for the first two, as well as the dynamics of GDP per capita at the regional level. We found higher and significant correlations between GDP per capita and urban–rural interfaces, but no significant correlations in the case of city cores. Our conclusion is that, in the transition period, the dynamics of urban–rural interfaces influenced more regional development dynamics, than those of city cores. This means that urban–rural interfaces amplify the development coming from cities, adding their own contribution and then dissipating it regionally. Future research should identify what the urban–rural interface offers to regions, in addition to the city core.

Interfacial enhancement by constructing a “flexible-rigid” structure between high-modulus fillers and low-modulus matrix in carbon fiber/silicone rubber composites

Silicone rubber (SR) has excellent resistance to high temperatures, and carbon fiber (CF) is a commonly reinforced material. However, the application of carbon fiber in SR composites is limited by the large difference in modulus between the two materials. In order to improve the interfacial bonding of the composites and to exert the reinforcement of carbon fibers, a modulus transition interface, a “flexible-rigid” structure was constructed between CF and SR by coating polydopamine-polyethyleneimine@silica (PDA-PEI@SiO2) on the carbon fiber surface. The results show that the “flexible-rigid” structure of the PDA-PEI@SiO2 layer not only enhanced the mechanical properties but also improved the thermal resistance and wave-transmission properties of the CF/SR composites. Surface microscopy and structural analysis showed that the “flexible-rigid” structure was successfully coated on the fiber surface, and significantly improved the roughness of the fiber surface. It provided the mechanical meshing between the fiber and matrix when the CF/SR composites were subjected to the tensile loads. The tensile strength and elongation of the SR composite with CF-A-E@8SiO2 were 37.16 % and 27.46 % higher than that with unmodified CF, respectively. The electrical test showed that the “flexible-rigid” structure could reduce the dielectric constant and dielectric loss of CF/SR composites, thereby improving the wave-transmission properties. Further mechanism analysis of the interfacial bonding showed that abundant hydrogen bonds in the “flexible-rigid” structure at the interface promoted stress dissipation and avoided stress concentration. Meanwhile, the formation of Si-O-Si with high bonding energy also protected the interface from destruction. The thermogravimetric analysis (TGA) found that the introduction of Si-O-Si bonds could significantly improve the thermal resistance of the CF/SR composites at 350 °C for 2 h. It provides guidance for the improvement of the interface bonding in the fiber/rubber composite as well as its functionality.

Nanocavity-Mediated Purcell Enhancement of Er in TiO2 Thin Films Grown via Atomic Layer Deposition.

The use of trivalent erbium (Er3+), typically embedded as an atomic defect in the solid-state, has widespread adoption as a dopant in telecommunication devices and shows promise as a spin-based quantum memory for quantum communication. In particular, its natural telecom C-band optical transition and spin-photon interface make it an ideal candidate for integration into existing optical fiber networks without the need for quantum frequency conversion. However, successful scaling requires a host material with few intrinsic nuclear spins, compatibility with semiconductor foundry processes, and straightforward integration with silicon photonics. Here, we present Er-doped titanium dioxide (TiO2) thin film growth on silicon substrates using a foundry-scalable atomic layer deposition process with a wide range of doping controls over the Er concentration. Even though the as-grown films are amorphous after oxygen annealing, they exhibit relatively large crystalline grains, and the embedded Er ions exhibit the characteristic optical emission spectrum from anatase TiO2. Critically, this growth and annealing process maintains the low surface roughness required for nanophotonic integration. Finally, we interface Er ensembles with high quality factor Si nanophotonic cavities via evanescent coupling and demonstrate a large Purcell enhancement (≈300) of their optical lifetime. Our findings demonstrate a low-temperature, nondestructive, and substrate-independent process for integrating Er-doped materials with silicon photonics. At high doping densities this platform can enable integrated photonic components such as on-chip amplifiers and lasers, while dilute concentrations can realize single ion quantum memories.

Mechanics and Stability of Force Chain Arch in Excavated Granular Material

Rock and soil masses in geotechnical engineering projects, such as tunnels, mines and slopes, undergo relative motion, exhibiting mechanical characteristics of solid–fluid transition under critical conditions. This work analyzes the characteristics of the solid–fluid transition interface and the mode of load transfer through biaxial compression particle flow photoelastic experiments on granular materials. The study documents that this interface forms an arch shape, marked by a force chain arch. The granular material exhibits two distinct states depending on its position: below the arch, the granular material is in a solid–fluid transitional state, with bearing capacity reduced, while above the arch, it is in a stable solid state, capable of bearing the overlying rock layer’s load. The presence of the force chain arch alters the direction of the originally downward-transferring load, redirecting it along the trajectory of the arch. Analysis of the force and stability of the force chain arch revealed that the arch shape parameters and boundary loads control the instability of the arch. Changes in the overlying and lateral loads lead to different types of instability of the force chain arch. The findings of the study are crucial for underground engineering construction and for the prevention of geological disasters related to granular material.

Design of railway transition zones: A novel energy-based criterion

Railway transition zones (RTZs) experience higher rates of degradation compared to open tracks, which leads to increased maintenance costs and reduced availability. Despite existing literature on railway track assessment and maintenance, effective design solutions for RTZs are still limited. Therefore, a robust design criterion is required to develop effective solutions. This paper presents a two-step approach for the formulation of a preliminary-design criterion to delay the onset of processes leading to uneven track geometry in RTZs. Firstly, a systematic analysis of each track component in a RTZ is performed by examining spatial and temporal variations in kinematic responses, stresses and energies using a finite element model of an embankment-bridge transition. Secondly, the study proposes an energy-based criterion to be assessed using a model with linear elastic material behavior and states that an amplification in the total train energy in the proximity of the transition interface is an indicator of increased (and thus non-uniform) degradation in RTZs compared to the open tracks. The correlation between the total strain energy (assessed in the model with linear material behaviour) and the permanent irreversible deformations is demonstrated using a model with non-linear elastoplastic material behavior of the ballast layer. In the end, it is claimed that minimising the magnitude of total strain energy will lead to reduced degradation and a uniform distribution of total strain energy in each trackbed layer along the longitudinal direction of the track will ensure uniformity in the track geometry.

PyRETIS3: Conquering rare and slow events without boundaries.

We present and discuss the advancements made in PyRETIS3, the third instalment of our Python library for an efficient and user-friendly rare event simulation, focused to execute molecular simulations with replica exchange transition interface sampling (RETIS) and its variations. Apart from a general rewiring of the internal code towards a more modular structure, several recently developed sampling strategies have been implemented. These include recently developed Monte Carlo moves to increase path decorrelation and convergence rate, and new ensemble definitions to handle the challenges of long-lived metastable states and transitions with unbounded reactant and product states. Additionally, the post-analysis software PyVisa is now embedded in the main code, allowing fast use of machine-learning algorithms for clustering and visualising collective variables in the simulation data.

How does the heterogeneous interface influence hydraulic fracturing?

Under the influence of the nonlinear fluid-solid coupling, hydraulic fracture exhibits various propagation modes (such as toughness- or viscosity-dominated), which stem from the competition between the solid deformation and fluid flow. Based on the homogeneous assumption, the basic theoretical analysis has divided toughness and viscosity scales in the tip region. However, regarding more realistic and complex geological conditions, like layered heterogeneity, knowledge of fluid-driven fracture propagation is still unclear. This work establishes a theoretical model and solving approach to reveal the multiscale asymptotic behavior during hydraulic fracture passing through the heterogeneous interface (i.e., discontinuous elastic properties). The influence of material discontinuity, regarded as the remote force, in the near-tip, intermediate, and far-field scales is analyzed by the asymptotic analysis and validated by the numerical solutions. Notably, solutions at the intermediate scale manifest as individual feature owing to the heterogeneity: as the crack in front of the interface, just a specific transition solution governed by the property and position of the interface appears; once the crack tip passes the interface, the interface-governed transition solution and interface solution occur simultaneously and interact as the crack tip moves away from the interface. Such multiscale property results in the interface-governed fluid-solid interaction in the tip region, and finally leads to changes in interface failure and propagation mode. On the one hand, the criterion for interface failure should be modified by simultaneously incorporating the heterogeneity of solid domain and multiscale nature of tip solution, especially for viscosity- or interface-dominated propagation regimes. On the other hand, the propagation mode in a heterogeneous domain is controlled by two characteristics: traditional l/lmk for toughness-viscosity competition associated with c/Lμ for material discontinuity effect proposed in the present work. These insights provide the theoretical foundation for modeling hydraulic fracture propagation in layered heterogeneous domains.

Copper sulfide deposition and remobilisation triggered by non-magmatic fluid incursion in the single-intrusion Tongchang porphyry system, SE China

Porphyry ore deposits are a major source of base and precious metals. Likewise, they bear important fingerprints for understanding magmatic / hydrothermal processes in the convergent margin. For many decades, the sources of non-magmatic fluid and its role in sulfide mineralization in the porphyry hydrothermal systems have been equivocal. The Tongchang porphyry deposit, which is a single intrusive system with a well-established fluid history, is investigated to reconstruct its hydrothermal process that contributed to the ore formation. In-situ oxygen and strontium isotopes in hydrothermal quartz and anhydrite revealed a coexistence of magmatic and non-magmatic fluid reservoirs. The granodiorite—derived magmatic fluid and external groundwater were spatially separated by a hydrologically impermeable shell formed by retrograde mineral deposition (mainly quartz). The location of the impermeable shell coincided with a brittle-ductile transition (BDT) interface established in the host phyllite in response to latent heating by the cooling magmas. It is inferred that the ductile phyllite beneath the impermeable shell may have entrained some amounts of groundwater and remnant metamorphic fluid. The early fluid stage was dominated by the magmatic fluids, forming disseminated chalcopyrite and barren quartz veins in the potassic-altered ductile granodiorite at high temperatures (> 500 °C). The next stage (early-intermediate) was also driven by the circulation of the magmatic fluids, but in a largely brittle zone formed in-between the impermeable shell and the retreated BDT interface (similar to the so-called “carapace” in the orthomagmatic models). In this stage the formation of pyrite and chalcopyrite veins together with chloritic alteration at temperatures of 400–350 °C occurred. The late-intermediate stage was marked by incursion of the trapped non-magmatic fluids due to rupturing of the enlarged carapace. Mixing of the non-magmatic fluids and the magmatic fluids led to deposition of a major phase of vein-type Cu sulfide at temperatures of 350–300 °C. The late fluid stage was characterized by breaching of the impermeable shell in response to volumetric contraction of the fluid system, leading to excessive infiltration of groundwater and ore remobilization. Based on the Tongchang model, six generic fluid models are proposed for porphyry ore deposits that differ in availability of non-magmatic components as well as intrusive histories. The models can account for variabilities in ore and alteration styles found in porphyry ore deposits globally.