Atomic Structure Of Interface Research Articles

Influence of Substrate Polarity on Thermal Stability, Grain Growth and Atomic Interface Structure of Au Thin Films on ZnO Surfaces

Influence of Substrate Polarity on Thermal Stability, Grain Growth and Atomic Interface Structure of Au Thin Films on ZnO Surfaces

DWBuilder: A code to generate ferroelectric/ferroelastic domain walls and multi-material atomic interface structures

DWBuilder: A code to generate ferroelectric/ferroelastic domain walls and multi-material atomic interface structures

Computational and Experimental Investigations of the Au and NiOOH Interface in the Oxygen Evolution Reaction

The transition to renewable energy sources is crucial for combating climate change, and hydrogen (H2) is a promising clean fuel. Electrolysis of water, specifically the oxygen evolution reaction (OER), is a key process for producing H2. Prior experimental results have shown that gold (Au) could improve the apparent activities of the OER electrocatalysts such as nickel hydroxide (Ni(OH)2) in alkaline electrolytes.1-3 However, the detailed interfacial atomic structure and mechanisms of the increased catalytic activity remain poorly understood.To understand the interfacial effect between Au and Ni(OH)2 in the OER process, our research uses the model system of Au nanoparticles (NPs) and nickel oxyhydroxide (NiOOH), which is the active phase of Ni(OH)2 layers in the OER, to investigate their interfacial interactions with both experimental and computational approaches. We hypothesize that the Au NPs on NiOOH enhances the OER activity by promoting electron transfer at the interface. Our studies involve computational analysis using Density Functional Theory (DFT) calculations to obtain the local density of states (LDOS), which can help us better visualize and compare the local electronic structure of NiOOH in the presence and in the absence of AuNPs. Two architectures of the Au and NiOOH interface will be investigated: Au NPs on a NiOOH film and NiOOH NPs on a Au film.Additionally, Bader analysis is employed to determine the Bader charge, offering a more detailed understanding of how electrons are distributed across the AuNPs/NiOOH interface. Furthermore, the catalytic efficacy of AuNPs on NiOOH is assessed through electrodepositions followed by cyclic voltammetry(CV) measurements. The experimental and computational results will be directly compared, and this research is expected to contribute to the insights of substrate and catalyst interactions for design of more efficient electrocatalysts.

Atomic Interface Engineering‐Mediated Metallene Nanozyme Boosts Efficient Photothermal Catalytic Tumor‐Specific Therapy

AbstractTumor microenvironment (TME)‐responsive nanozymes‐based catalytic therapy shows great potential in combating malignant tumor. However, their biological application still suffers from deficient catalytic activity. Herein, the MoOx‐Rh metallene nanozyme demonstrates highly efficient multiple enzymatic catalytic activities, where MoOx species atomically dispersed on Rh metallene surface. The resulting structures enable MoOx‐Rh metallene with maximally exposed active oxide‐metallene interface and more atoms sites around interface can be well finely regulated. Results of experiment and density functional theory (DFT) simulations support the notion that atomic interface structure facilitates multiple enzyme‐like reactions. As a TME‐responsive nanozyme, MoOx‐Rh metallene exhibits remarkable therapeutic effect of tumor due to intrinsic near‐infrared photothermal effect and laser‐enhanced multiple enzymatic catalytic activities. This study illustrates the great promise of atomic interface engineering strategy in tumor catalytic therapy.

A new method for characterizing the atomic composition distribution and interface structure of ultrathin multilayer films using molecular dynamics simulation assisted ARXPS

Characterizing ultrathin multilayer films' atom distribution and interface structure remains challenging. This paper innovatively characterized the chemical composition and distribution of Pt/Co/W ultrathin multilayer films by ARXPS. Molecular dynamics simulated the growth process of films to correspond to that in experiment. The results show that through ARXPS, the actual structure of Pt (2 nm)/Co (t = 0.5–3 nm)/W (2 nm) film could be obtained. For Pt (2 nm)/Co (2 nm)/W (2 nm) film, the actual structure was Pt/Co (1.73 nm)/W (0.78 nm)/WO3 + WO2 (1.48 nm). W at the top layer significantly diffused to the bottom layers, and oxidized W reduced from the surface to the interior of multilayer films. Molecular dynamics simulation confirmed that the interdiffusion degree of Co and W atoms was improved with the increase of Co atoms. The growth modes of Co and W layers were respectively layer-by-layer and island. As the number of Co atoms increased, the relative surface roughness of Co and W layers and the relative interface roughness of Co/W were increased. The in-plane magnetic anisotropy and coercivity were respectively enhanced and decreased due to the change in the surface/interface structure. This paper provides a new idea for analyzing ultrathin multilayer films' atom distribution and interface structure.

Orientation Relationship of the Intergrowth Al13Fe3 and Al13Fe4 Intermetallics Determined by Single-Crystal X-ray Diffraction

In the Al-Fe binary system, the Al13Fe3 phase as well as the Al13Fe4 phase has similar icosahedral building blocks like those appearing in quasicrystals. Therefore, it is of vital importance to clarify the formation process of these two phases. Coexistence of the Al13Fe3 and Al13Fe4 phases was discovered from the educts obtained with a nominal atomic ratio of Al/Fe of 9:2 by high-pressure sintering for the first time. Firstly, single crystal X-ray diffraction (SXRD) combined with a scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDX) measurement capabilities were adopted to determine the detailed crystal structures of both phases, which were sharply refined with regard to Al13Fe3 and Al13Fe4. Secondly, the orientation relationship between Al13Fe3 and Al13Fe4 was directly deduced from the SXRD datasets and the coexistence structure model was consequently constructed. Finally, seven pairs of parallel atomic planes and their unique orientation relations were determined from the reconstructed reciprocal space precession images. In addition, the real space structure model of the intergrowth crystal along with one kind of interfacial atomic structure were constructed from the determined orientation relations between two phases.

Modeling Si/SiGe quantum dot variability induced by interface disorder reconstructed from multiperspective microscopy

SiGe heteroepitaxial growth yields pristine host material for quantum dot qubits, but residual interface disorder can lead to qubit-to-qubit variability that might pose an obstacle to reliable SiGe-based quantum computing. By convolving data from scanning tunneling microscopy and high-angle annular dark field scanning transmission electron microscopy, we reconstruct 3D interfacial atomic structure and employ an atomistic multi-valley effective mass theory to quantify qubit spectral variability. The results indicate (1) appreciable valley splitting (VS) variability of ~50% owing to alloy disorder and (2) roughness-induced double-dot detuning bias energy variability of order 1–10 meV depending on well thickness. For measured intermixing, atomic steps have negligible influence on VS, and uncorrelated roughness causes spatially fluctuating energy biases in double-dot detunings potentially incorrectly attributed to charge disorder. Our approach yields atomic structure spanning orders of magnitude larger areas than post-growth microscopy or tomography alone, enabling more holistic predictions of disorder-induced qubit variability.

Orientation Relationship of Intergrowth Al2Fe and Al5Fe2 Intermetallics Determined by Single-Crystal X-ray Diffraction

Although the Al2Fe phase has similar decagonal-like atomic arrangements as that of the orthorhombic Al5Fe2 phase, no evidence for intergrowth samples of Al2Fe and Al5Fe2 has been reported. In the present work, the co-existence of Al2Fe and Al5Fe2 phases has been discovered from the educts obtained with a nominal atomic ratio of Al:Fe of 2:1 by arc melting. First, single-crystal X-ray diffraction (SXRD) as well as scanning electron microscope (SEM) equipped with energy-dispersive X-ray spectroscopy (EDX) measurements have been utilized to determine the exact crystal structures of both phases, which are refined to be Al12.48Fe6.52 and Al5.72Fe2, respectively. Second, the orientation relationship between Al2Fe and Al5Fe2 has been directly deduced from the SXRD data sets, and the co-existence structure model has been constructed. Finally, four pairs of parallel atomic planes and their unique orientation relations have been determined from the reconstructed reciprocal-space precession images of (0kl), (h0l), and (hk0) layers. In addition, one kind of interface atomic structure model is constructed by the orientation relations between two phases, correspondingly.

Spaced-Confined Janus Engineering Enables Controlled Ion Transport Channels and Accelerated Kinetics for Secondary Ion Batteries.

The large grain boundary resistance between different components of the anode electrode easily leads to the low ion transport efficiency and poor electrochemical performance of lithium-/sodium-ion batteries (LIBs/SIBs). To address the issue, a Janus heterointerface with a Mott-Schottky structure is proposed to optimize the interface atomic structure, weaken interatomic resistance, and improve ion transport kinetics. Herein, Janus Co/Co2P@carbon-nanotubes@core-shell (Janus Co/Co2P@CNT-CS) refined urchin-like architecture derived from metal-organic frameworks is reported via a coating-phosphating process, where the Janus Co/Co2P heterointerface nanoparticles are confined in carbon nanotubes and a core-shell polyhedron. Such a Janus Co/Co2P heterointerface shows the strong built-in electric field, facilitating the controllable ion transport channels and the high ion transport efficiency. The Janus Co/Co2P@CNT-CS refined urchin-like architecture composed of a core-shell structure and the grafting carbon nanotubes enhances the structure stability and electronic conductivity. Benefiting from the spaced-confined Janus heterointerface engineering and synergistic effects between the core-shell structure and the grafting carbon nanotubes, the Janus Co/Co2P@CNT-CS refined urchin-like architecture demonstrates the fast ion transport rate and excellent pseudocapacitance performance for LIBs/SIBs. In this case, the Janus Co/Co2P@CNT-CS refined urchin-like architecture shows high specific capacities of 709 mA h g-1 (200 cycles) and 203 mA h g-1 (300 cycles) at a current density of 500 mA g-1 for LIBs/SIBs, respectively.

Controllable Sulfurization of MXenes to In‐Plane Multi‐Heterostructures for Efficient Sulfur Redox Kinetics

AbstractAlthough in‐plane heterostructure with high ion transport pathway and unique interfacial atomic structure offers endless possibilities in the catalysis field, it is still challenging to directly synthesize MXene‐based in‐plane heterostructure due to the differences in crystal structures and growth conditions. Here, Mo2C–MoS2 in‐plane multi‐heterostructures are synthesized by topological conversion of sandwich‐like mesoporous Mo2C–SiO2 layers in sulfur vapor and subsequent removal of SiO2. During the conversion process, the exposed Mo2C will efficiently converted to 2H phase MoS2, meanwhile, the covered Mo2C remained stable, affording metallic Mo2C MXene and semiconducting MoS2 in‐plane multi‐heterostructures compatible in one layer. The resultant Mo2C–MoS2 layer has multiple heterointerfaces, build‐in electric fields as well as abundant defects. Such structural features enable to improve of the electrochemical active surface area (16.4 mF cm−2), which not only facilitates the bidirectional sulfur electrochemistry between solid Li2S and soluble lithium polysulfides, but also enhances the transfer kinetics of electrons and ions, giving rise to a high‐rate performance (642 mAh g−1 at 5 C) and a long‐term cycle life (1000 cycles at 5 C) in lithium–sulfur batteries.

Mnemonic Rutile-Rutile Interfaces Triggering Spontaneous Dissociation of Water.

Water interaction with mineral surfaces is a complex living system decisive for any photocatalytic process. Resolving the atomistic structure of mineral-water interfaces is thus crucial for understanding these processes. Fibrous rutile TiO2 , grown hydrothermally on twinned rutile seeds under acidic conditions, is studied in terms of interface translation, atomic structure, and surface chemistry in the presence of water, by means of advanced microscopy and spectroscopy methods combined with structure modeling and density functional theory calculations. It is shown that fibers while staying in stable separation during their growth, adopt a special crystallographic registry that is controlled by repulsion forces between fully hydroxylated and protonated (110) surfaces. During relaxation, a turbulent proton transfer and cracking of O─H bonds is observed, generating a strong acidic character via proton jump from bridge ─OHb to terminal ─OHt groups, and spontaneous dissociation of interfacial water via a transient protonation of the ─OHt groups. It is shown, that this specific interface structure can be implemented to induce acidic response in an initially neutral medium when re-immersed. This is thought to be the first demonstration of quantum-confinedmineral-water interface, capable of memorizing its past and conveying its structurally encoded properties into a new environment.

Interface atomic structures in a cadmium arsenide/III–V semiconductor heterostructure

The interface atomic structure between an epitaxial thin film of the prototype topological semimetal cadmium arsenide (Cd3As2) and a III–V semiconductor layer is investigated using high-angle annular dark-field imaging in an aberration-corrected scanning transmission electron microscope. We find that the interface unit cell adopts a defined stoichiometry that is CdSb-like, which is achieved through the insertion of periodically arranged Cd vacancies in the terminating Cd-plane of Cd3As2. This interface stoichiometry is consistent with the Sb-termination of the III–V layer and the fact that CdSb is the thermodynamically stable phase in the Cd–Sb binary system. We find at least two distinct alignments of the film with respect to the buffer layer, which are characterized by a 14100Cd3As2 shift parallel to the interface. We show that steps of half unit cell height in the III–V layer can produce these distinct interface structures.

Enhancing the Photocatalytic Activity of Zirconium-Based Metal-Organic Frameworks Through the Formation of Mixed-Valence Centers.

Despite the desirability of metal-organic frameworks (MOFs) as heterogeneous photocatalysts, current strategies available to enhance the performance of MOF photocatalysts are complicated and expensive. Herein, a simple strategy is presented for improving the activity of MOF photocatalysts by regulating the atomic interface structure of the metal active sites on the MOF. In this study, MOF (PCN-222) is hybridized with cellulose acetate (CA@PCN-222) through an optimized atomic interface strategy, which lowers the average valence state of Zr ions. The electronic metal-support interaction mechanism of CA@PCN-222 is revealed by evaluating the photocatalytic CO2 reduction reaction (CO2 RR). The experimental results suggested that the electron migration efficiency at the atomic interface of the MOFs strongly coupled with cellulose is significantly improved. In particular, the CO2 RR to formate activity of CA@PCN-222 photocatalyst greatly increased from 778.2 to 2816.0µmolg-1 compared with pristine PCN-222 without cellulose acetate. The findings suggest that the strongly coupled metal-ligand moiety at the atomic interface of MOFs may play a synergistic role in heterogeneous catalysts.

Boron substitution induced FCC Fe/Cr23C6 interfacial strengthening: An ab initio study

Boron is added to stainless steels and polycrystalline superalloys to promote ductility, corrosion resistance, and retard creep at high temperatures (above 700 °C). However, the role of local atomic environment(s) and how boron may impact the interfacial properties between the Cr23C6 precipitate, and the matrix are not fully understood. In the present work, we consider the face-centered cubic (FCC) Fe (001)/Cr23C6 (001) interface as a model system to study how the interfacial local atomic structure and energy are affected by boron doping using first-principles density functional theory (DFT) calculations. The atomic structure(s) and energetics of a coherent interface were calculated by including the elastic contribution using linear elasticity theory combined with DFT. Boron has a significant effect on the interfacial energy and the atomic arrangement near the interface region through the increased covalent bonding, thereby ordering the interface and making any diffusion processes less favorable energetically. In turn, this may contribute to the retardation of the Cr23C6 precipitate growth and coarsening. Because of the concurrent precipitation of the NbC, Cr23C6, and Sigma phases, it affects the whole cascade of microstructural evolution processes contributing to creep. More specifically, the ancillary additions of boron to the A-terminated Cr23C6 significantly reduce the interfacial energy (∼0.09 J/m2) between the iron matrix and the Cr23C6: from ∼ 0.38 J/m2 without doping to 0.29 J/m2 with doping. This interfacial energy decrease due to boron additions is an important factor in interface strengthening and retarding creep in austenitic stainless steels. Such B-induced short-range order interface strengthening is facilitated via promoting interface covalence bonding and considerable local lattice distortion due to the atomic size misfit. These results were obtained using the new interface model described in the paper. This new interface model allows to quantitatively distinguish the highly complex asymmetric interface structures and corresponding interfacial energies and surface energies.

Atomic resolution interface structure and vertical current injection in highly uniform MoS2 heterojunctions with bulk GaN

The integration of two-dimensional MoS2 with GaN recently attracted significant interest for future electronic/optoelectronic applications. However, the reported studies have been mainly carried out using heteroepitaxial GaN templates on sapphire substrates, whereas the growth of MoS2 on low-dislocation-density bulk GaN can be strategic for the realization of “truly” vertical devices. In this paper, we report the growth of ultrathin MoS2 films, mostly composed by single-layers (1L), onto homoepitaxial n−-GaN on n+ bulk substrates by sulfurization of a pre-deposited MoOx film. Highly uniform and conformal coverage of the GaN surface was demonstrated by atomic force microscopy, while very low tensile strain (∼0.05%) and a significant p+-type doping (∼4.5 × 1012 cm−2) of 1L-MoS2 was evaluated by Raman mapping. Atomic resolution structural and compositional analyses by aberration-corrected electron microscopy revealed a nearly-ideal van der Waals interface between MoS2 and the Ga-terminated GaN crystal, where only the topmost Ga atoms are affected by oxidation. Furthermore, the relevant lattice parameters of the MoS2/GaN heterojunction, such as the van der Waals gap, were measured with high precision. Finally, the vertical current injection across this 2D/3D heterojunction has been investigated by nanoscale current-voltage analyses performed by conductive atomic force microscopy, showing a rectifying behavior with an average turn-on voltage Von = 1.7 V under forward bias, consistent with the expected band alignment at the interface between p+ doped 1L-MoS2 and n-GaN.

Interfacial interaction and intense interfacial ultraviolet light emission at an incoherent interface

Incoherent interfaces with large mismatches usually exhibit very weak interfacial interactions so that they rarely generate intriguing interfacial properties. Here we demonstrate unexpected strong interfacial interactions at the incoherent AlN/Al2O3 (0001) interface with a large mismatch by combining transmission electron microscopy, first-principles calculations, and cathodoluminescence spectroscopy. It is revealed that strong interfacial interactions have significantly tailored the interfacial atomic structure and electronic properties. Misfit dislocation networks and stacking faults are formed at this interface, which is rarely observed at other incoherent interfaces. The band gap of the interface reduces significantly to ~ 3.9 eV due to the competition between the elongated Al-N and Al-O bonds across the interface. Thus this incoherent interface can generate a very strong interfacial ultraviolet light emission. Our findings suggest that incoherent interfaces can exhibit strong interfacial interactions and unique interfacial properties, thereby opening an avenue for the development of related heterojunction materials and devices.

First-principles study on the interfacial bonding strength and segregation at Mg/MgZn2 matrix interface

To understand the interface characteristics between the precipitate β2′ and the Mg matrix, and thus guide the development of new Mg-Zn alloys, we investigated the atomic interface structure, work of adhesion (Wad), and interfacial energy (γ) of Mg(0001)/β2'(MgZn2)(0001) interface, as well as the effect of segregation behavior of the introduced transition metal atoms (3d, 4d and 5d) on interfacial bonding strength. The calculated works of adhesion and interfacial energies dementated that the Zn2-terminated MT+HCP configuration is the most stable structure for all considered models. Take the Zn2- MT+HCP interface as the research object, estimated segregated energies (Eseg) reveal that added transition metal atoms prefer to segregate at Mg-I and Mg-II sites. The predicted Wad and charge density difference results reveal that the segregation of alloying additives employed may all strengthen Mg(0001)/MgZn2(0001) interface, with the enhancement effect of Os, Re, Tc, W, and Ru at the Mg-II site being the most pronounced.

Investigation of the nucleation and growth behavior of Ti2AlC and Ti3AlC nano-precipitates in TiAl alloys

Abstract In this work, the nucleation and growth behavior of Ti2AlC and Ti3AlC nano-precipitates in Ti–44Al–1.2C alloys were systematically studied by observing their distribution, morphology, and interface atomic structure. The experiment results show that the needle-like C atom segregation zones in TiAl alloys are the nucleation site of Ti2AlC, and the long axis direction of segregation zones is parallel to the TiAl(111) plane. The rod-like Ti2AlC nano-precipitates mainly distribute at the TiAl/Ti3Al interface, and the orientation relationship between them is [ 1 ̅ 01 \bar{1}01 ]TiAl//[ 11 2 ̅ 0 11\bar{2}0 ]Ti2AlC//[ 11 2 ̅ 0 11\bar{2}0 ]Ti3Al, (111)TiAl//(0001)Ti2AlC//(0001)Ti3Al. The needle-like Ti3AlC nano-precipitates distribute in TiAl with the orientation relationship of [001]Ti3AlC//[001]TiAl, (100)Ti3AlC//(100)TiAl, (020)Ti3AlC//(020)TiAl, and (110)Ti3AlC//(110)TiAl during the nucleation stage. After growing into the rod-like, the orientation relationship between Ti3AlC precipitates and TiAl is [ 1 1 ̅ 0 1\bar{1}0 ]Ti3AlC//[ 1 1 ̅ 0 1\bar{1}0 ]TiAl, (001)Ti3AlC//(001)TiAl, (220)Ti3AlC//(220)TiAl, and (111)Ti3AlC//(111)TiAl. Both the needle- and rod-like Ti3AlC precipitates preferentially grow along the [001]TiAl direction. The crystal structure and lattice mismatch between Ti2AlC and Ti3AlC nano-precipitates and the TiAl matrix determine their distribution, morphology, and interface atomic structure.

Atomic Imaging of Interface Defects in an Insulating Film on Diamond.

The insulator/semiconductor interface structure is the key to electric device performance, and much interest has been focused on understanding the origin of interfacial defects. However, with conventional techniques, it is difficult to analyze the interfacial atomic structure buried in the insulating film. Here, we reveal the atomic structure at the interface between an amorphous aluminum oxide and diamond using a developed electron energy analyzer for photoelectron holography. We find that the three-dimensional atomic structure of a C-O-Al-O-C bridge between two dimer rows of the hydrogen-terminated diamond surface. Our results demonstrate that photoelectron holography can be used to reveal the three-dimensional atomic structure of the interface between a crystal and an amorphous film. We also find that the photoelectron intensity originating from the C-O bonds is strongly related to the interfacial defect density. We anticipate significant progress in the study of amorphous/crystalline interfaces based on their three-dimensional atomic structures analysis.

Insight into the interface structure and its effect on the oxidation in pearlite U-2Nb alloy

Atomic interface structure of in pearlite U-2wt.%Nb (U-2Nb) alloy and its effect on the oxidation are investigated by HRSTEM combined with FIB. The crystallographic orientation relationship between α and γ phase is determined: and . The interfaces of are relatively coherent. Under air oxidation, α phase takes precedence to attract oxygen compared with interface. The key role affecting oxidation of the alloy could attribute to the characteristic of α phase with high activity instead of the interfaces. This work may provide fundamental insight into the interface-related corrosion behavior in pearlite alloys.