Showing papers on "Liquid metal published in 2019"
TL;DR: In this paper, it is shown that under mechanical agitation liquid metal droplets are established, and simultaneously, hydrated gallium oxides and manganese oxide sheets delaminate themselves from the interfacial boundaries.
Abstract: Liquid metals offer unprecedented chemistry. Here it is shown that they can facilitate self-limiting oxidation processes on their surfaces, which enables the growth of metal oxides that are atomically thin. This claim is exemplified by creating atomically thin hydrated MnO2 using a Galvanic replacement reaction between permanganate ions and a liquid gallium–indium alloy (EGaIn). The “liquid solution”–“liquid metal” process leads to the reduction of the permanganate ions, resulting in the formation of the oxide monolayer at the interface. It is presented that under mechanical agitation liquid metal droplets are established, and simultaneously, hydrated gallium oxides and manganese oxide sheets delaminate themselves from the interfacial boundaries. The produced nanosheets encapsulate a metallic core, which is found to consist of solid indium only, with the full migration of gallium out of the droplets. This process produces core/shell structures, where the shells are made of stacked atomically thin nanosheets. The obtained core/shell structures are found to be an efficient photocatalyst for the degradation of an organic dye under simulated solar irradiation. This study presents a new research direction toward the modification and functionalization of liquid metals through spontaneous interfacial redox reactions, which has implications for many applications beyond photocatalysis.
153 citations
TL;DR: A liquid-metal electrocatalyst to convert CO2 directly into solid carbon that can be used as capacitor electrodes is demonstrated and may result in a viable negative emission technology.
Abstract: Negative carbon emission technologies are critical for ensuring a future stable climate. However, the gaseous state of CO2 does render the indefinite storage of this greenhouse gas challenging. Herein, we created a liquid metal electrocatalyst that contains metallic elemental cerium nanoparticles, which facilitates the electrochemical reduction of CO2 to layered solid carbonaceous species, at a low onset potential of −310 mV vs CO2/C. We exploited the formation of a cerium oxide catalyst at the liquid metal/electrolyte interface, which together with cerium nanoparticles, promoted the room temperature reduction of CO2. Due to the inhibition of van der Waals adhesion at the liquid interface, the electrode was remarkably resistant to deactivation via coking caused by solid carbonaceous species. The as-produced solid carbonaceous materials could be utilised for the fabrication of high-performance capacitor electrodes. Overall, this liquid metal enabled electrocatalytic process at room temperature may result in a viable negative emission technology.
148 citations
TL;DR: Remarkable electromechanical properties, responsive behaviors, and facile processing make Poly-LMNs ideal for stretchable power delivery, sensing, and circuitry.
Abstract: Room-temperature liquid metals, such as nontoxic gallium alloys, show enormous promise to revolutionize stretchable electronics for next-generation soft robotic, e-skin, and wearable technologies. Core-shell particles of liquid metal with surface-bound acrylate ligands are synthesized and polymerized together to create cross-linked particle networks comprising >99.9% liquid metal by weight. When stretched, particles within these polymerized liquid metal networks (Poly-LMNs) rupture and release their liquid metal payload, resulting in a rapid 108 -fold increase in the network's conductivity. These networks autonomously form hierarchical structures that mitigate the deleterious effects of strain on electronic performance and give rise to emergent properties. Notable characteristics include nearly constant resistances over large strains, electronic strain memory, and increasing volumetric conductivity with strain to over 20 000 S cm-1 at >700% elongation. Furthermore, these Poly-LMNs exhibit exceptional performance as stretchable heaters, retaining 96% of their areal power across relevant physiological strains. Remarkable electromechanical properties, responsive behaviors, and facile processing make Poly-LMNs ideal for stretchable power delivery, sensing, and circuitry.
132 citations
112 citations
TL;DR: In this paper, the state-of-the-art progress in fabricating methods, highlight unique features, and discuss applications of liquid metal micro/nanoparticles in biomedicine, soft electronics, thermal management and soft motors.
Abstract: Liquid metal is a liquid-state metallic material with a low melting point at or around room temperature. Owing to their high thermal or electrical conductivity, low viscosity and superior fluidity, liquid metals are emerging as a highly desirable candidate in a broad array of areas, such as flexible electronics, thermal management, soft machines and biomedical materials. However, bulk liquid metal is not readily utilized because of its high surface tension and large dimension-induced dexterity limitations. To address this challenge, liquid metals have been innovated with micro/nanotechnology to endow the bulk liquid metals with remarkably diversified performances. These new functional materials not only possess the softness of classical liquid metals but also have many outstanding properties, including great thermal conductivity, self-healing ability and stimuli-responsive deformability. Compared to rigid inorganic micro/nanoscale materials, soft liquid metal micro/nanoparticles demonstrate their unconventionally superior flexibility, compliance and tunability. This review is dedicated to summarize the state-of-the-art progress in fabricating methods, highlight unique features, and discuss applications of liquid metal micro/nanoparticles in biomedicine, soft electronics, thermal management and soft motors. Future outlooks, including both opportunities and scientific challenges of liquid metal micro/nanoparticles, are also presented here.
112 citations
TL;DR: In this paper, the status of the development of liquid metal anodes is summarized and the current challenges of the liquid metal electrodes (LME) as electrodes for rechargeable batteries.
Abstract: Liquid metals (LM) and alloys that feature inherent deformability, high electronic conductivity, and superior electrochemical properties have attracted considerable research attention, especially in the energy storage research field for both portable devices and grid scale applications. Compared with high temperature LM systems requiring rigorous thermal management and sophisticated cell sealing, room temperature LMs, which can maintain the advantageous features of liquids without external energy input, are emerging as promising alternatives to build advanced energy storage devices. Moreover, compared with high-temperature liquid metal alternatives, RT-LMs are free of thermal management, corrosion, and sealing issues. In this perspective, we summarize recent advances, analyze current challenges, and provide prospects of the RT-LM systems as electrodes for rechargeable batteries. Starting with an introduction of LM systems and their features, we present the status of the development of liquid metal anodes. Theoretical and experimental explorations of mechanisms including phase equilibria, wetting behavior, and alloy deposition behavior in a battery using liquid metal electrodes (LME) are provided to guide the battery design. Taking Na–K alkali metal alloys and Ga-based fusible alloys as two model LME systems, different battery designs are presented along with mechanistic discussions on cathode dependence, interfacial chemistry, and the multi-cation effect. In addition, other possible battery designs, major challenges, and possible opportunities for further developments of the RT LM-based energy storage systems are also discussed in the end.
109 citations
TL;DR: It is shown that the formation of a nanometer-scale LM oxide in oxygen-rich environments allows highly nonwetting tungsten particles to mix into LMs, and the oxide-assisted mechanism behind this wetting process is revealed.
Abstract: Modern microelectronics and emerging technologies such as wearable devices and soft robotics require conformable and thermally conductive thermal interface materials to improve their performance and longevity. Gallium-based liquid metals (LMs) are promising candidates for these applications yet are limited by their moderate thermal conductivity, difficulty in surface-spreading, and pump-out issues. Incorporation of metallic particles into the LM can address these problems, but observed alloying processes shift the LM melting point and lead to undesirable formation of additional surface roughness. Here, these problems are addressed by introducing a mixture of tungsten microparticles dispersed within a LM matrix (LM-W) that exhibits two- to threefold enhanced thermal conductivity (62 ± 2.28 W m-1 K-1 for gallium and 57 ± 2.08 W m-1 K-1 for EGaInSn at a 40% filler volume mixing ratio) and liquid-to-paste transition for better surface application. It is shown that the formation of a nanometer-scale LM oxide in oxygen-rich environments allows highly nonwetting tungsten particles to mix into LMs. Using in situ imaging and particle dipping experimentation within a focused ion beam and scanning electron microscopy system, the oxide-assisted mechanism behind this wetting process is revealed. Furthermore, since tungsten does not undergo room-temperature alloying with gallium, it is shown that LM-W remains a chemically stable mixture.
92 citations
10 Jul 2019
TL;DR: Tang et al. as discussed by the authors presented an in situ investigation of phase behavior for gallium-based liquid metal nanoparticles and discovered the unprecedented coexistence of solid particles in spherical liquid metal shells without the support of a crystalline substrate.
Abstract: Nanoparticles produced from gallium-based liquid metal alloys have been explored for developing applications in the fields of electronics, catalysis, and biomedicine. Nonetheless, physical properties, such as phase behavior at micro-/nanosize scale, are still significantly underexplored for such nanoparticles. Here, we conduct an in situ investigation of phase behavior for gallium-based liquid metal nanoparticles and discover the unprecedented coexistence of solid particles in spherical liquid metal shells without the support of a crystalline substrate. The particles can also transform into solid Janus nanoparticles after temperature cycling. In addition, we investigate the optical properties of the nanoparticles before and after phase separation using in situ electron energy-loss spectroscopy. Most importantly, we discover that increasing the content of indium within the nanoparticle can stabilize the solid-core/liquid-shell structure at room temperature. This study provides a foundation to engineer liquid metal nanoparticles for developing new applications in nanoscale optical platforms and shape-configurable transformers.Although various electronic, chemical, and biomedical applications have been demonstrated for nanoparticles made from gallium-based liquid metal alloys, fundamental physical properties such as phase behavior of such nanoparticles are still significantly underexplored. Here, Tang and coworkers present the in situ investigation of phase separation in binary and ternary spherical liquid metal nanoparticles upon cooling, and demonstrate the coexistence of solid core/liquid shell without the support of a crystalline substrate. This study provides insight into engineering such nanoparticles for the development of new applications.Despite gallium-based liquid metal alloys attracting extensive attention for various applications, their phase behavior at the nanoscale is still underexplored. Understanding the impact of phase separation in nanoparticles can be extremely useful for developing new structures and exploring suitable applications. Here, we report on the investigation of phase behavior for spherical nanoparticles made from gallium-based liquid metal alloys upon cooling. We discover the thermally stable coexistence of solid cores in spherical liquid metal shells without the support of a crystalline substrate at room temperature. Given the unique properties of liquid metal, together with the facile process for producing core-shell and Janus nanoparticles, this work will encourage further investigation of the properties of such nanoparticles for developing applications in the fields of electronics, catalysis, nanomedicine, and beyond.
90 citations
TL;DR: In this article, a vapor cavity generating ultrasonic platform for nebulizing liquid metal within aqueous media for the one-step production of stable and functional liquid metal NPs is shown.
Abstract: Functional liquid metal nanoparticles (NPs), produced from eutectic alloys of gallium, promise new horizons in the fields of sensors, microfluidics, flexible electronics, catalysis, and biomedicine. Here, the development of a vapor cavity generating ultrasonic platform for nebulizing liquid metal within aqueous media for the one-step production of stable and functional liquid metal NPs is shown. The size distribution of the NPs is fully characterized and it is demonstrated that various macro and small molecules can also be grafted onto these liquid metal NPs during the liquid-based nebulization process. The cytotoxicity of the NPs grafted with different molecules is further explored. Moreover, it is shown that it is possible to control the thickness of the oxide layer on the produced NPs using electrochemistry that can be embedded within the platform. It is envisaged that this platform can be adapted as a cost-effective and versatile device for the rapid production of functional liquid metal NPs for future liquid metal-based optical, electronic, catalytic, and biomedical applications.
69 citations
TL;DR: The proposed method enables eGaIn-based soft sensors or circuits to be connected to typical electronic components through FFCs or weldable surfaces, using only off-the-shelf materials without additional mechanical or chemical treatments.
Abstract: For wider applications of liquid metal-based stretchable electronics, electrical interface has remained a crucial issue due to its fragile electromechanical stability and complex fabrication steps....
66 citations
18 Apr 2019
TL;DR: Liquid alloys of gallium, their properties, and applications for e-skins are discussed in this review, and the wealth of opportunities for future applications within soft and stretchable electronics is explored.
Abstract: The implementation and exploration of liquid metals for soft electronics, especially electronic skins (e-skins), are fast increasing. The growing field has received special attention since research regarding gallium-based alloys has intensified as these alloys are much safer in comparison to their more hazardous counterpart, mercury. Liquid metal alloys of gallium provide unique physical and chemical properties for e-skin. These properties originate from their high thermal and electrical conductivities and the fact that the liquid metal is an electronic melt in contrast to the ionic liquid. The formation of 2-D oxides on the surface of liquid gallium alloys, with large van der Waals forces, also adds to their uniqueness. Liquid metals, whether in bulk form or particulated morphologies, provide stretchabilities that surpass any other systems, allowing for the formation of super malleable e-skins. As such, they present certain opportunities for developing elements with extraordinary softness, malleability, and skin compatibility: stretchable wires and electrodes, memories, electronic components such as resistors, coils, diodes, and transistors, soft sensors, energy harvesting/storage elements, and self-healing systems. Presence of the 2-D metal compound skin also helps in accessing the non-Newtonian characteristics of gallium-based alloys that permit the formation of microparticles/nanoparticles and specific fluidics and grant printability in three dimensions. Liquid alloys of gallium, their properties, and applications for e-skins are discussed in this review, and the wealth of opportunities for future applications within soft and stretchable electronics is explored.
TL;DR: In this article, a cellular automata model was used to predict the solidification microstructure evolution of laser powder bed fusion (PBF) fabricated 316 L stainless steel.
Abstract: This work presents a novel modeling framework combining computational fluid dynamics (CFD) and cellular automata (CA), to predict the solidification microstructure evolution of laser powder bed fusion (PBF) fabricated 316 L stainless steel. A CA model is developed which is based on the modified decentered square method to improve computational efficiency. Using this framework, the fluid dynamics of the melt pool flow in the laser melting process is found to be mainly driven by the competing Marangoni force and the recoil pressure on the liquid metal surface. Evaporation occurs at the front end of the laser spot. The initial high temperature occurs in the center of the laser spot. However, due to Marangoni force, which drives high-temperature liquid flowing to low-temperature region, the highest temperature region shifts to the front side of the laser spot where evaporation occurs. Additionally, the recoil pressure pushes the liquid metal downward to form a depression zone. The simulated melt pool depths are compared well with the experimental data. Additionally, the simulated solidification microstructure using the CA model is in a good agreement with the experimental observation. The simulations show that higher scan speeds result in smaller melt pool depth, and lack-of-fusion pores can be formed. Higher laser scan speed also leads to finer grain size, larger laser-grain angle, and higher columnar grain contents, which are consistent with experimental observations. This model can be potentially used as a tool to optimize the metal powder bed fusion process, through generating desired microstructure and resultant material properties.
TL;DR: This comprehensive comparison confirms the necessity of oxidation suppression and significant thermal stress via instantaneous laser irradiation to achieve conductive patterns in liquid form.
Abstract: Metallic inks with superior conductivity and printability are necessary for high-throughput manufacturing of printed electronics. In particular, gallium-based liquid metal inks have shown great potential in creating soft, flexible and stretchable electronics. Despite their metallic composition, as-printed liquid metal nanoparticle films are non-conductive due to the surrounding metal oxide shells which are primarily Ga2O3, a wide-bandgap semiconductor. Hence, these films require a sintering process to recover their conductivity. For conventional solid metallic nanoparticles, thermal and laser processing are two commonly used sintering methods, and the sintering mechanism is well understood. Nevertheless, laser sintering of liquid metal nanoparticles was only recently demonstrated, and to date, the effect of thermal sintering has rarely been investigated. Here, eutectic gallium–indium nanoparticle films are processed separately by laser or thermal sintering in an ambient environment. Laser and thermally sintered films are compared with respect to electrical conductivity, surface morphology and elemental composition, crystallinity and surface composition. Both methods impart thermal energy to the films and generate thermal stress in the particles, resulting in rupture of the gallium oxide shells and achieving electrical conductivity across the film. For laser sintering, extensive oxide rupture allows liquid metal cores to flow out and coalesce into conductive pathways. For thermal sintering, due to less thermal stress and more oxidation, the oxide shells only rupture locally and extensive phase segregation occurs, leading to non-liquid particle films at room temperature. Electrical conductivity is instead attributed to segregated metal layers and gallium oxide which becomes crystalline and conductive at high temperatures. This comprehensive comparison confirms the necessity of oxidation suppression and significant thermal stress via instantaneous laser irradiation to achieve conductive patterns in liquid form.
TL;DR: In this paper, the authors developed an innovative approach to obtain functional liquid metal (FLM) by modifying it with copper-iron magnetic nanoparticles (Cu-Fe NPs) and demonstrated the precise control and climbing locomotion of the FLM with the interworking of both electric and magnetic fields simultaneously.
Abstract: Gallium based room temperature liquid metal alloys have recently been explored to be an emerging functional material. They have attracted particular attentions in a variety of applications due to their unique properties. Many of the applications are based on the precise control over the motion of liquid metal, and yet, the fact that currently lacking the advanced and reliable controlling methods greatly hinders the potential of liquid metal to be applied in a wider range of fields. In this study, we develop an innovative approach to obtain functional liquid metal (FLM) by modifying it with copper-iron magnetic nanoparticles (Cu-Fe NPs). The magnetic modification process enables the Cu-Fe-NPs to be suspended within the liquid metal and form the FLM. The FLM exhibits similar appearance, actuating behaviors, and deformability in alkaline solutions to those of pure liquid metal alloys. Meanwhile, the magnetic modification enables the precise and rapid manipulation of the liquid metal using a magnetic field. Most importantly, for the first time, we demonstrated the precise control and climbing locomotion of the FLM with the interworking of both electric and magnetic fields simultaneously. The remarkable features of the FLM may represent vast potentials toward the development of future intelligent soft robots.
TL;DR: In this article, an experimental study was conducted to quantify the heat transfer coefficient of a liquid metal mixture including gallium, indium and tin (Ga-In-Sn) under various heat fluxes inside a compact heat exchanger equipped with rectangular micro-passages.
TL;DR: A direct comparison of the viscoelastic properties for gallium-based liquid metals is provided and a microstructural evolution of the interface occurs when aluminum preferentially migrates from the bulk to the surface as well as simple methods to optimize their rheological behavior for future applications are provided.
Abstract: Gallium and its alloys react with oxygen to form a native oxide that encapsulates the liquid metal with a solid “skin”. The viscoelasticity of this skin is leveraged in applications such as soft el...
TL;DR: A facile Eutectic Galium-Indium (EGaln) liquid-based microfluidic high-sensitivity, skin-mountable, and ultra-soft stretchable sensor is developed that achieves an outstanding effect on elastomer-encapsulated strain gauge, which displays an approximately linear behavior with a gauge factor (GF).
Abstract: Room-temperature liquid metal has been widely used in flexible and stretchable sensors, focusing on embedding liquid metal in microchannels, liquid metal microdroplets formation, captive sensors, and liquid metal nanoparticles, etc. In this paper, a facile Eutectic Galium-Indium (EGaln) liquid-based microfluidic high-sensitivity, skin-mountable, and ultra-soft stretchable sensor is developed. It comprises Ecoflex microfluidic assembly filled with EGaln, which serves as the working fluid of the stretchable sensor. The lithography method is applied to achieve microfluidic channel. The microfluidic channel is optimized by using topology method and finite element analysis, making this device with high conformability and high stretchability. This method achieved an outstanding effect on elastomer-encapsulated strain gauge, which displays an approximately linear behavior with a gauge factor (GF). The GF could reach as high as 4.95 when the strain ultimately reached 550%. Applications of detection of the joints, fingers, and wrists has been conducted and showed excellent results. This work can further facilitate the exploration and potential realization of a functional liquid-state device technology with superior mechanical flexibility and conformability.
TL;DR: In this article, the steel/zinc system creates the potential for liquid metal embrittlemen, which is a potential problem in automotive structural components, such as automotive structural component.
Abstract: Advanced high strength steels used in automotive structural components are commonly protected using zinc coatings. However, the steel/zinc system creates the potential for liquid metal embrittlemen...
TL;DR: In this paper, a flexible pressure sensor based on polydimethylsiloxane (PDMS) and eutectic gallium-indium (EGaIn) liquid metal was developed for detecting various applied pressures.
Abstract: A novel flexible pressure sensor, based on polydimethylsiloxane (PDMS) and eutectic gallium–indium (EGaIn) liquid metal, was developed for detecting various applied pressures. The sensor was fabricated with PDMS polymer-based electrode channels that are filled with EGaIn liquid metal. The liquid metal-based electrodes were designed to form four capacitors (C1, C2, C3, and C4). Conventional printed circuit board technology was used to manufacture the master mold to form the PDMS-based electrode channels. Corona discharge treatment was employed to bond the PDMS layers at room temperature, under atmospheric pressure. The capability of the fabricated pressure sensor was demonstrated by investigating the capacitive-based response of the device for varying applied pressures. Average capacitance changes ranging from 2.3% to 12.0%, 2.6% to 11.8%, 2.5% to 12.2%, and 2.7% to 13.1% when compared with the based capacitance of 14.1, 15.1, 13.8, and 13.3 pF were obtained for C1, C2, C3, and C4, respectively, for applied pressures ranging from 0.25 to 1.10 MPa. A linear relationship was obtained for the average capacitance change with a sensitivity of 0.11%/MPa and a correlation coefficient of 0.9975. The results obtained thus demonstrate the feasibility of employing liquid metal-based electrodes for the fabrication of flexible pressure sensing devices.
TL;DR: In this paper, a generalized method is proposed to fabricate temperature tunable liquid conductor-insulator transition composites, which is achieved firstly via freezing and thawing liquid metal droplets dispersed in dimethicone.
Abstract: Liquid materials with the ability to transit between conductor and insulator are of great scientific and practical significance. However, achieving the conduction of a liquid metal droplet network is still a challenge. To solve these problems, a generalized method is proposed to fabricate temperature tunable liquid conductor–insulator transition composites, which is achieved firstly via freezing and thawing liquid metal droplets dispersed in dimethicone. Such composites also impart conductivity to the dispersed liquid metal droplet network. To illustrate the typical application of the thus realized materials, a visualized circuit is constructed based on the relationship between the color and the conduction. In addition, reconfigurable and repairable circuits are fabricated depending on the inherent liquid properties of these materials. Furthermore, this universal mechanism has been revealed via the abnormal volume expansion ratio of the liquid metal droplets during the phase change. By calculating the volume change ratio of all metals, we speculate and confirm that gallium-based alloys and bismuth-based alloys can be used to prepare such conductive transition materials. Accordingly, we identify more eligible materials with suitable phase transition points, which significantly extends the transition temperature from insulator to conductor. The liquid material preparation strategy proposed here provides a novel paradigm for achieving the conductor–insulator transition at a wide temperature range and offers promising potential for future applications.
TL;DR: In this article, a variety of chemical strategies were introduced to produce EGaIn nanoparticles which exhibit a wide range of gallium oxide shell thicknesses, and these chemically modified oxide thicknesses were then correlated to the core-shell liquid nanoparticles' mechanical properties by subjecting the particles to orthogonal characterization techniques; XPS and nanoindentation were used to determine the onset of particle rupture and resultant conductivity.
Abstract: Eutectic gallium–indium (EGaIn) is a room temperature liquid metal that can be readily fabricated into nanoparticles which naturally form a thin, passivating gallium oxide shell. These core–shell nanoparticles are of interest for a variety of stimuli-responsive applications, which often utilize physical deformation of the particles to release the molten, conductive payload from within the gallium oxide shell. In the present work, we introduce a variety of chemical strategies to produce EGaIn nanoparticles which exhibit a wide range of gallium oxide shell thicknesses. These chemically modified oxide thicknesses are then correlated to the core–shell liquid nanoparticles’ mechanical properties by subjecting the particles to orthogonal characterization techniques; XPS for measurement of the gallium oxide shell thickness and nanoindentation for measurement of particle stiffness and elastic modulus. Additionally, nanoindentation is used to determine the onset of particle rupture and resultant conductivity. Ultimately, quantification of the relationships between chemical treatment and derivative mechanical properties in liquid metal nanoparticles will enable advanced applications of these colloids, such as in tailored self-healing and responsive electronic devices.
TL;DR: In this paper, an experimental investigation was conducted on the fluid flow and heat transfer characteristics of gallium-indium eutectic flowing in the microchannel passages and the influence of low-frequency vibration at two frequencies and amplitudes on the overall heat transfer coefficient and thermo-hydraulic performance of the micro channel was also studied and discussed.
TL;DR: In this paper, the authors obtained the millimeter-size graphene single crystals on liquid Cu and showed that the rich free-electrons in liquid Cu accelerate the nucleation, and the isotropic smooth surface greatly suppresses nucleation.
Abstract: Previous reports about the growth of large graphene single crystals on polycrystalline metal substrates usually adopted the strategy of suppressing the nucleation by lowering the concentration of the feedstock, which greatly limited the rate of the nucleation and the sequent growth. The emerging liquid metal catalyst possesses the characteristic of quasi-atomically smooth surface with high diffusion rate. In principle, it should be a naturally ideal platform for the low-density nucleation and the fast growth of graphene. However, the rapid growth of large graphene single crystals on liquid metals has not received the due attention. In this paper, we firstly purposed the insight into the rapid growth of large graphene single crystals on liquid metals. We obtained the millimeter-size graphene single crystals on liquid Cu. The rich free-electrons in liquid Cu accelerate the nucleation, and the isotropic smooth surface greatly suppresses the nucleation. Moreover, the fast mass-transfer of carbon atoms due to the excellent fluidity of liquid Cu promotes the fast growth with a rate up to 79 µm s–1. We hope the research on the growth speed of graphene on liquid Cu can enrich the recognition of the growth behavior of two-dimensional (2D) materials on the liquid metal. We also believe that the liquid metal strategy for the rapid growth of graphene can be extended to various 2D materials and thus promote their future applications in the photonics and electronics.
TL;DR: In this paper, the phase composition of cladding layer on diamond particles is analyzed by transmission electron microscopy combined with focused ion beam technology to measure the thermal conductivity of gallium-based thermal interface materials (TIMs).
Abstract: The focus of this paper is how to efficiently enhance the thermal conductance of gallium-based thermal interface materials (TIMs) and greatly avoid the excessive consumption of liquid metal during its application. Highly heat-conducting diamond particles are selected as the reinforced additives for pure gallium on account of their mature technology of surface metallization. To improve the interface combination status between those inorganic fillers and liquid metal matrix, chromium transition layer is deposited on the surfaces of diamond particles by magnetron sputtering method. The phase composition of cladding layer on diamond particles is analyzed by transmission electron microscopy combined with focused ion beam technology. To measure the thermal conductivity of gallium-based TIM filled with chromium-coated diamond particles, a specific three-layer structure sample is made for laser flash analysis and the corresponding theoretical fitting model is deduced subsequently. After performing iterative solution through programming, our results present that 47 wt% addition of chromium-coated diamond particles can dramatically increase the thermal conductivity of pure gallium from 29.3 to 112.5 W/(m·K) at room temperature. And fortunately, it has not yet been observed that the chromium coating is over consumed by liquid metal or the thermal conductivity of composite seriously degrades after thermal aging treatment at 80 °C for 192 h, strongly indicating that chromium could be used as the diffusion barrier layer for heat-conducting particles and the metal substrates to maintain long-term reliable service of gallium-based TIMs.
TL;DR: In this paper, the multi-layered oxide scales forming on an austenitic stainless steel fuel cladding exposed to oxygen-containing (CO ≈ 10−6 mass%) static liquid lead-bismuth eutectic (LBE) for 1000h between 400 and 500h was analyzed, including the intertwined phases comprising the innermost biphasic layer.
TL;DR: It is demonstrated that the scattering of metamaterials can be switched and that their operating band can be tuned by introducing liquid metal in the design of functional metammaterials.
Abstract: Novel manipulation techniques for the propagation of electromagnetic waves based on metamaterials can only be performed in narrow operating bands, and this drawback is a major challenge for developing metamaterial-based practical applications. We demonstrate that the scattering of metamaterials can be switched and that their operating band can be tuned by introducing liquid metal in the design of functional metamaterials. The proposed liquid metal-based metamaterial is composed of a copper wire pair and a tiny pipe filled with a liquid metal, namely eutectic gallium-indium. The interference of the sharp magnetic resonance of the copper wire pair and the broad dipolar mode of the liquid metal rod lead to an electromagnetically induced transparency (EIT)-like spectrum. We experimentally demonstrate that this EIT-like behavior can be switched on or off by exploiting the fluidity of the liquid metal, which is useful for multi-frequency modulators. These findings will hopefully promote the development of fluid matter-based metamaterials for extending the operating band of novel electromagnetic functions.
TL;DR: In this paper, it is shown that it is possible to produce particles of Field's metal (an alloy of bismuth 32.5 wt%, tin 16.5wt% and indium 51wt%) in a one-step mechanical agitation (ultrasonication) procedure.
Abstract: Exploring the concept of liquid processing and solidification of low melting point alloys can provide new routes for the creation of functional micro and nanoparticles. Here we show that it is possible to produce particles of Field's metal (an alloy of bismuth 32.5 wt%, tin 16.5 wt% and indium 51 wt%) in a one-step mechanical agitation (ultrasonication) procedure. The synthesis takes place just above 62 °C, the melting point of Field's metal, and results in the formation of low-dimensional particles after solidification. It is demonstrated that the sonication process produces nearly spherical core-shell metal-metal oxide heterostructures. Classic alloy-related defects, in the forms of grain boundaries and edge locations, emerge after the solidification. We show that by the incorporation of Ag, either using direct alloying or an Ag salt precursor during the sonication process, this metal appears in the core of the metal-metal oxide heterostructures. Interestingly, the modification of particles with Ag gives specific selectivity for the degradation of two typical azo dyes. The one-step low-temperature synthesis and solidification procedure, presented in this work, can be readily extended for designing catalysts or other functional materials with desired specificity and selectivity.
TL;DR: In this article, the authors found that charging and discharging cycles may show pronounced asymmetries due to the presence (charge) or absence (discharge) of solutal convection.