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2D transition metal dichalcogenides (TMDs) play increasingly significant roles in research and future optoelectronics. However, the large-scale deposition of 2D TMDs remains challenging due to sparse nucleation and substrate dependency. Liquid metals can offer effective solutions to meet these challenges due to their reactive, non-polarized, and templating properties. Here, self-deposition of 2D molybdenum sulfide is shown by introducing a molybdenum precursor onto the surface of a eutectic alloy of gallium and indium (EGaIn). EGaIn serves as an ultra-smooth template and reducing agent for the precursor to form large-scale planar molybdenum sulfides, which is transferrable to any substrate. The molybdenum sulfides form spontaneously on the surface of EGaIn, which has a sufficient potential to drive the cathodic reactions of the deposition process. A highly crystalline 2H-MoS2 is obtained after a final annealing step. This work demonstrates a fundamentally new capability for the formation of large-scale 2D TMDs.

Phonon-polaritons (PhPs) in layered crystals, including hexagonal boron nitride (hBN), have been investigated by combined scattering-type scanning near-field optical microscopy (s-SNOM) and Fourier transform infrared (FTIR) spectroscopy. Nevertheless, many of such s-SNOM-based FTIR spectra features remain unexplored, especially those originated from the impact of boundaries. Here we observe real-space PhP propagations in thin-layer hBN sheets either supported or suspended by s-SNOM imaging. Then with a high-power broadband IR laser source, we identify two major peaks and multiple auxiliary peaks in the near-field amplitude spectra, obtained using scattering-type near-field FTIR spectroscopy, from both supported and suspended hBN. The major PhP propagation interference peak moves toward the major in-plane phonon peak when the IR illumination moves away from the hBN edge. Specific differences between the auxiliary peaks in the near-field amplitude spectra from supported and suspended hBN sheets are investigated regarding different boundary conditions, associated with edges and substrate interfaces. The outcomes may be explored in heterostructures for advanced nanophotonic applications.

The nascent field of nanotechnology-enabled metallurgy has great potential. However, the role of eutectic alloys and the nature of alloy solidification in this field are still largely unknown. To demonstrate one of the promises of liquid metals in the field, we explore a model system of catalytically active Bi-Sn nano-alloys produced using a liquid-phase ultrasonication technique and investigate their phase separation, surface oxidation, and nucleation. The Bi-Sn ratio determines the grain boundary properties and the emergence of dislocations within the nano-alloys. The eutectic system gives rise to the smallest grain dimensions among all Bi-Sn ratios along with more pronounced dislocation formation within the nano-alloys. Using electrochemical CO2 reduction and photocatalysis, we demonstrate that the structural peculiarity of the eutectic nano-alloys offers the highest catalytic activity in comparison with their non-eutectic counterparts. The fundamentals of nano-alloy formation revealed here may establish the groundwork for creating bimetallic and multimetallic nano-alloys.

Crystallization of alloys from a molten state is a fundamental process underpinning metallurgy. Here the direct imaging of an intermetallic precipitation reaction at equilibrium in a liquid‐metal environment is demonstrated. It is shown that the outer layers of a solidified intermetallic are surprisingly unstable to the depths of several nanometers, fluctuating between a crystalline and a liquid state. This effect, referred to herein as crystal interface liquefaction, is observed at remarkably low temperatures and results in highly unstable crystal interfaces at temperatures exceeding 200 K below the bulk melting point of the solid. In general, any liquefaction process would occur at or close to the formal melting point of a solid, thus differentiating the observed liquefaction phenomenon from other processes such as surface pre‐melting or conventional bulk melting. Crystal interface liquefaction is observed in a variety of binary alloy systems and as such, the findings may impact the understanding of crystallization and solidification processes in metallic systems and alloys more generally. [ABSTRACT FROM AUTHOR]

Spatial community detection is a method that divides geographic spaces into several sub-regions based on spatial interactions, reflecting the regional spatial structure against the background of human mobility. In recent years, spatial community detection has attracted extensive research in the field of geographic information science. However, mining the community structures and their evolutionary patterns from spatial interaction data remains challenging. Most existing methods for spatial community detection rely on representing spatial interaction networks in Euclidean space, which results in significant distortion when modeling spatial interaction networks; since spatial community detection has no ground truth, this results in the detection and evaluation of communities being difficult. Furthermore, most methods usually ignore the dynamics of these spatial interaction networks, resulting in the dynamic evolution of spatial communities not being discussed in depth. Therefore, this study proposes a framework for community detection and evolutionary analysis for spatial interaction networks. Specifically, we construct a spatial interaction network based on network science theory, where geographic units serve as nodes and interaction relationships serve as edges. In order to fully learn the structural features of the spatial interaction network, we introduce a hyperbolic graph convolution module in the community detection phase to learn the spatial and non-spatial attributes of the spatial interaction network, obtain vector representations of the nodes, and optimize them based on a graph generation model to achieve the final community detection results. Considering the dynamics of spatial interactions, we analyze the evolution of the spatial community over time. Finally, using taxi trajectory data as an example, we conduct relevant experiments within the fifth ring road of Beijing. The empirical results validate the community detection capabilities of the proposed method, which can effectively describe the dynamic spatial structure of cities based on human mobility and provide an effective analytical method for urban spatial planning. [ABSTRACT FROM AUTHOR]

Silicon carbide fiber reinforced silicon carbide matrix (SiCf/SiC) composite is the key cladding material of nuclear fuel, which determines the safety and reliability of nuclear fuel storage and transportation. The replacement of its storage and transportation scenario needs to be completed by the manipulator, but the application of SiCf/SiC wear, fracture, and nuclear leakage in the snatching process of brittle-flexible-rigid contact in the irradiation environment has been seriously restricted due to unclear understanding of the damage mechanism. Therefore, the effects of irradiation dose and clamping load on the friction characteristics of the contact interface between SiCf/SiC clad tube are studied in this paper, and the effects of irradiation parameters and clamping force on the static friction coefficient of the contact interface between the clad tube and flexible nitrile are obtained. Based on the Greenwood-Williamson tribological model, a numerical model of the shape and structure of the contact micro-convex at the micro-scale of the clamping interface is constructed by introducing the multi-surface integral, and finally verified by experiments. The research results show that there is a unique "Irradiation suppression zone" under the clamping condition of SiCf/SiC cladding tube under the nuclear irradiation environment, and the growth of static friction coefficient slows down until stagnates after irradiation reaches a certain extent (600 kGy), and there will be a decline when the irradiation dose continues to increase, among which the clamping force of 15.2 N within the irradiation interval of 1,000 kGy can meet the safety of nuclear environment operation. The results of this paper can provide an important theoretical basis and application guidance for the safe operation of SiCf/SiC cladding tubes in the storage and transportation clamping process. [ABSTRACT FROM AUTHOR]