Gallium Alloy Research Articles

Effects of a horizontal magnetic field on the cross-sectional distribution of gas bubbles chain rising in a gallium alloy

Understanding the behavior of rising bubbles in a liquid metal under the influence of a magnetic field (MF) is crucial for optimizing continuous casting processes. The study experimentally investigated the effects of a horizontal MF on the behavior of bubble chains in a gallium alloy. High-speed ultrasonic computed tomography was used to measure the instantaneous bubble crossing positions in a cylindrical column with an inner diameter of 50 mm. With an increase in the MF strength, the oscillations of the bubbles were suppressed, resulting in the crossing position being concentrated in a certain area of the cross-section. The fluctuations in the time intervals of the chain bubbles decreased. These effects were more pronounced when the magnetic interaction parameter (or Stuart number) was greater than 1. The distribution of bubbles in the direction perpendicular to the MF was widespread slightly compared to that in the direction parallel to the MF; this was noticeable at higher flow rates. The suppression of the wake turbulence induced by the Lorentz force was larger in the direction parallel to the MF than that in the direction perpendicular to the MF. Our results have the potential to be used for the direct verification of numerical models.

Liquid Metal in Expired Artificial Kidneys: A Nanoporous Soft Conductive Wire Platform for Unconventional Interfacial Fluidic Studies

AbstractStrong chemical or voltage‐driven studies of gallium alloys (liquid metal, LM) show methods of altering the surface energy of the bare alloys by controlling Ga2O3 (Gallium Oxide)‐ a 3‐5 nm surface oxide that forms on LM. However, various fluids (i.e., water) interact weakly compared to strong acids or bases and do not etch Ga2O3. Specialized instruments are often required to study such interactions, which are not readily available. Herein, an LM‐based nanoporous conductive wire platform is demonstrated, which can effectively be utilized for real‐time weaker interfacial studies. The unconventional platform allows fluid transport and interfacial studies within the nanoporous domain, which is still foreign in the literature. Nanoporous conductive wires are fabricated by injecting eutectic gallium indium (eGaIn) into hollow microtubes collected from expired and unused artificial kidneys. These steps upcycle medical waste and confine Ga2O3 at the nanopores for an inexpensive metal‐oxide/metal framework. The platform for interfacial fluidics is harnessed, leveraging deionized (DI) water, 1 m hydrochloric acid (HCl), and 95% ethanol (EtOH). This study also demonstrates capacitive sensors that can be immediately implemented using nanoporous conducive wires. Advanced applications from this study suggest that future exploration of such soft systems can lead to more nano/bioanalyses harnessing LM alloys.

Interaction of Gallium with a Copper Surface: Surface Alloying and Formation of Ordered Structures.

Alloys of gallium with transition metals have recently received considerable attention for their applications in microelectronics and catalysis. Here, we investigated the initial stages of the Ga-Cu alloy formation on Cu(111) and Cu(001) surfaces using scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and low energy electron diffraction (LEED). The results show that Ga atoms deposited using physical vapor deposition readily intermix with the Cu surface, leading to a random distribution of the Ga and Cu atoms within the surface layer, on both terraces and monolayer-thick islands formed thereon. However, as the Ga coverage increases, several ordered structures are formed. The (√3×√3)R30° structure is found to be thermodynamically most stable on Cu(111). This structure remains after vacuum annealing at 600 K, independent of the initial Ga coverage (varied between 0.5 and 3 monolayers), indicating a self-limited growth of the Ga-Cu alloy layer, with the rest of the Ga atoms migrating into the Cu crystal. For Ga deposited on Cu(001), we observed a (1 × 5)-reconstructed surface, which has never been observed for surface alloys on Cu(001). The experimental findings were rationalized on the basis of density functional theory (DFT) calculations, which provided structural models for the most stable surface Ga-Cu alloys on Cu(111) and Cu(001). The study sheds light on the complex interaction of Ga with transition metal surfaces and the interfaces formed thereon that will aid in a better understanding of surface alloying and chemical reactions on the Ga-based alloys.

Simulations of optical properties of gallium alloy nanorods based on aspect ratio and shell thickness

Liquid plasmonics in contemporary research heavily relies on gallium-based alloy nanoparticles (NPs). The focus of this study is to explore the plasmonic properties of rod-shaped gallium alloy nanoparticles. The primary aim is to examine how variations in Ag shell thickness and aspect ratio affect the optical properties based on localized surface plasmon resonance (LSPR). The outcomes of this study will provide invaluable insights into improving the performance of plasmonic nanostructures. Notably, the focus is solely on analyzing the impact of size and material on the plasmon resonance of gallium-based alloy (GaAg), distinguishing it from the more widely known eutectic gallium-indium (EGaIn) alloy and Galinstan. To investigate the influence of varying aspect ratios and noble metal shell thickness under three different light polarization conditions, the boundary element method (BEM) was utilized. MATLAB-based simulations were employed to generate near-field and far-field plots of the extinction profiles of these nanorods. A large amount of tuning of the extinction spectra observed in the visible domain (380–780 nm) of the electromagnetic spectrum can be achieved with the size variation parameters. The gallium alloy (GaAg) examined in this study exhibits superior plasmonic properties and can be effectively utilized in soft electronic components, plasmonic energy storage devices, and as an alternative to the widely promoted GaIn alloy.

A novel fast response and high precision water temperature sensor based on Fiber Bragg Grating

A novel fast response and high precision water temperature sensor scheme based on gallium alloy sensitivity enhanced Fiber Bragg Grating(FBG) is proposed and experimentally demonstrated. In order to achieve faster temperature response speed of the sensor, a fiber Bragg grating is encapsulated in a single-end sealed metal tube which is filled with liquid gallium alloy. The very high thermal conductivity of the liquid gallium alloy that is filled in the metal tube gives rise to an experimental sensitivity of 30 pm/℃. Thanks to accurate and optimal design of metal tube structure parameters, the sensor exhibits an excellent response speed of 43 ms/℃ in water. Very good linearity between center wavelength of FBG and temperature is also achieved in the experiment. The research result of this paper is especially useful for applications where rapid temperature response and high precision are required at the same time, such as ocean CTD(Conductivity Temperature Depth) measuring equipment, ocean hydrology and underwater submersible.

Kinetics calculation of Al/Ga interfacial diffusion in sandwich geometry model

Gallium alloys have been attracting significant renewed attention for actively triggerable metals of advanced manufacturing via liquid metal embrittlement. This study is devoted to understanding mechanism of liquid metal embrittlement by a new perspective on the diffusion kinetics of gallium in aluminum matrix. The interfacial diffusion between liquid gallium and pure aluminum has been systematically investigated through sandwich geometry diffusion model analysis at different temperatures. Diffusion activation energy and diffusion coefficient of Al/Ga diffusion couple were calculated, and the diffusion kinetics model was established as well. The diffusion activation energy of gallium in aluminum matrix can be estimated to be 41.5 kJ/mol. The relationship between the mean-squared diffusion distance, time and temperature is the following: d=0.178exp(−4990T)t.

Characteristics for Gallium-Based Liquid Alloys of Low Melting Temperature

Gallium alloys are ideal base carriers for temperature-sensitive ferrofluids, which can be used for energy convection, soft robotics, microchannels, magnetorheological devices, etc. In this study, gallium was mixed with different substances (In, Sn, Zn, Ge, and Al) to obtain a low melting point, reduce the wetness and adhesion of its alloys, and realize low viscosity. The melting point, contact angle on certain solid plates, viscosity, and viscoelasticity of the gallium alloys were measured, and some useful gallium alloys were obtained. The experimental results showed that Ga80In10Sn10 had lower wettability at a larger contact angle of 148.6° on the Teflon plate. Here, (Ga80In10Sn10)97Zn3 with a melting point of 8.2 °C, lower than the melting point of Galinstan, was developed. It had a viscosity about three times that of water at room temperature and an elastic response from 0.1 to 100 Hz at a 1% strain amplitude for the viscoelasticity. It was expected that a kind of temperature-sensitive magnetic fluid with a gallium-based liquid alloy as the base carrier liquid would be prepared in the future with Teflon as the container to achieve energy conversion under the drive of the magnetic field.

Evaluation of Behavior of Continuous Bubbles Rising in a Gallium Alloy under Influence of Horizontal Magnetic Field by Using a High-speed Ultrasonic Tomography

In the continuous casting process, argon gas is injected into the tundish to homogenize the molten steel and remove the undesired inclusion. Furthermore, the molten steel flow is controlled by applying a magnetic field to the mold. The inclusion of argon gas as the molten steel flows into the mold can lead to product defects. Therefore, it is essential to predict the motion of the bubble in liquid metals under influence of the magnetic field, and further investigations are required for the liquid-metal two-phase flows. However, measurement techniques which can be applicable to opaque fluids such as liquid meat are limited. The authors have developed a high-speed ultrasonic tomography for measuring bubbles motion and investigated the behavior of continuously released bubbles motion in gallium alloy under influence of a horizontal magnetic field. The ultrasonic tomography measurements were carried out with 500 frames per second. It was shown that as the magnetic field strength increases, the variation of the bubble passing position in the measurement cross-section becomes smaller. Furthermore, it was confirmed that the distribution changed slightly depending on the direction of the applied magnetic field and that the bubbles tended to distribute in the direction perpendicular to the magnetic field. This trend changes depending on the difference in the gas flow rate. It is thought that the greater the influence of the wake, the more pronounced the anisotropy of the distribution.

Magneto electric sensor based on cantilever coated galfenol/ AlN structure

Ultrasensitive magnetic field sensors based on magnetoelectric (ME) structures have many applications in bio-magnetic sensors and magnetoencephalography (MEG) scanners. Enhance the sensitivity, limit of detection and main frequency of these sensors need simulation process by accurate methods such as finite element method (FEM). To get good sensitivity and efficient benefit, we use a cantilever-type composite structures including galfenol alloy as a magnetostrictive layer and AlN as a piezoelectric layer. Galfenol is an alloy of iron and gallium and its Fe0.83Ga0.17 structure has a high magnetostriction coefficient and can be used as a thin film. This simulated sensor can measure an AC magnetic field with field resolution in the order of 1pT. This sensor has the best performance in the bias DC magnetic field of 2.3 mT and resonance frequency of 2521.8 Hz and has a magnetoelectric coefficient of 4865 (V/cm.Oe).

Actively Triggerable Metals via Liquid Metal Embrittlement for Biomedical Applications.

Actively triggerable materials, which break down upon introduction of an exogenous stimulus, enable precise control over the lifetime of biomedical technologies, as well as adaptation to unforeseen circumstances, such as changes to an established treatment plan. Yet, most actively triggerable materials are low-strength polymers and hydrogels with limited long-term durability. By contrast, metals possess advantageous functional properties, including high mechanical strength and conductivity, that are desirable across several applications within biomedicine. To realize actively triggerable metals, a mechanism called liquid metal embrittlement is leveraged, in which certain liquid metals penetrate the grain boundaries of certain solid metals and cause them to dramatically weaken or disintegrate. In this work, it is demonstrated that eutectic gallium indium (EGaIn), a biocompatible alloy of gallium, can be formulated to reproducibly trigger the breakdown of aluminum within different physiologically relevant environments. The breakdown behavior of aluminum after triggering can further be readily controlled by manipulating its grain structure. Finally, three possible use cases of biomedical devices constructed from actively triggerable metals are demonstrated.

Индукционный метод локализации фронта кристаллизации

The paper describes the development and testing of an inductive sensor designed for determining the position of the solidification front of electricallyconductive melts. The operation of the sensor is based on the eddy current transducer principle. We compared induction and ultrasonic methods of localizing the solidification front of a gallium alloy on a model problem of directional solidification of liquid metal in a flat vertical layer. The principles of the induction method are described, its ap-plicability is shown, the measurement error has been found.

Hydrotalcite-derived nickel–gallium alloy catalysts with enhanced resistance against metal sintering for methane decomposition

Catalytic methane decomposition is a promising way to convert methane into COx-free hydrogen and value-added carbon nanomaterials, but the development of a sintering-resistant catalyst is a challenge. In this study, Ni–Ga/Al2O3 alloy catalysts with different Ga/Ni atomic ratios were prepared from Ni3−xGaxAl (x = 0–1.2) hydrotalcite-like compounds (HTlcs) as precursors and tested for methane decomposition. Structural and physicochemical properties of the as-prepared and used catalysts were characterized by ICP, N2 physical adsorption, XRD, H2-TPR, H2 chemisorption, STEM-EDX, SEM, TEM, and Raman techniques. The results indicate that upon calcination at 500 °C, Ni–Ga–Al HTlcs are transferred to rock-salt Ni(Ga,Al)O oxide solid solutions, and reduction with H2 at 800 °C leads to single-phase and composition-uniform Ni–Ga alloy particles with an average crystal size of 8–10 nm. In catalytic methane decomposition at 600 °C, the alloying Ni with a suitable amount of Ga effectively enhances the catalyst life and carbon yield. Especially, Ni2.4Ga0.6Al shows the highest carbon yield of 61.1 g-C/g-cat, approximately 4.4 times that of the Ga-free Ni counterpart. Meanwhile, Ni–Ga alloying has a marked influence on the CNTs geometry, giving herringbone-like CNTs with small diameters and thin walls. It is gratifying to find that the Ni–Ga/Al2O3 catalyst exhibits good resistance against sintering under the adopted reaction condition, which accounts for the formation of uniform CNTs of smaller size. The findings provide guidelines for the control of carbon morphology and geometric size in methane decomposition.

Magnetostrictive Ultrasonic Waveguide Transducer for In-Pile Thermometry

Real-time and reliable temperature measurement on nuclear fuels is crucial for the safe operation of existing pressurized-water reactors and future advanced nuclear reactors. Magnetostrictive materials deform when subjected to a magnetic field or exhibit magnetization variation when stressed. Based on these properties, this study prototyped an ultrasonic thermometer (UT) consisting of a magnetostrictive waveguide, a dc coil providing appropriate magnetic biasing, and an ac coil generating an acoustic impulse and detecting the resulting acoustic echoes. By tracking the time of flight between the excitation pulse and the echoes, the UT can potentially detect nuclear fuel cladding temperature from a long distance. In this study, magnetostrictive iron–gallium alloys, or Galfenol, were selected as the waveguide due to their large magnetostriction, superior temperature survivability, excellent radiation resilience, and high mechanical robustness. A multiphysics finite-element model considering electrical, magnetic, and mechanical dynamics in the magnetostrictive UT was then developed. The model exhibited an error of 0.24% in time-of-flight simulation and, therefore, enabled computer-aided design and guided signal processing. Between room temperature and 120 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> C, the new Galfenol-based UT exhibits a linear sensitivity of 162.8 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\times 10{^{-6}} {^\circ }$</tex-math></inline-formula> C <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{-1}$</tex-math></inline-formula> , which is 51.7% higher than a previous magnetostrictive UT based on iron–cobalt–vanadium alloys.

Modular Bioinspired Hand with Multijoint Rigid-Soft Finger Possessing Proprioception.

Soft robot hands have the advantage of remarkable adaptability for grasping. Especially for the soft and fragile objects, soft fingers had presented their much excellent potential compared with their rigid counterparts. However, less degree of freedom, lower force output, lack of proprioception, and poor controllability still limit the application. Inspired by the anatomical structure of the human hand and following the idea of combining soft joints, rigid skeletons and embedded soft curvature sensors, modular dexterous hands composed of multijoint fingers are proposed in this study. Each finger has three quasi-joints, in which metacarpophalangeal soft-joint can realize adduction/abduction and bending motions, and distal two interphalangeal soft-joints are actuated by one actuator. Similar to human hand, soft-joint so-called quasi-joint has a short length of constant curvature segment. The integrated Indium Gallium Alloy sensors with Kelvin Bridge for proprioception can accurately detect joint angles, while closed-loop control based on proprioception was accomplished. Kinematics and statics modeling method of the rigid-soft finger is proposed. To further verify the performance of this design, prototypes of three-fingered and five-fingered hands are developed. The multifingered hands had demonstrated their capability of adaptive grasp and dexterous manipulation, while the force output of the three-fingered hand is up to 31.82 N, and 32 grasp types had accomplished by the five-fingered hand.

Correlated Study of Material Interaction Between Capillary Printed Eutectic Gallium Alloys and Gold Electrodes (Small 42/2022)

Liquid Metal Electronics In article number 2202987, Michael Hirtz and co-workers take a close look at gold/liquid metal contacts as they appear, e.g., in flexible electronics. By correlating complementary chemical and morphological characterization techniques, new details on the evolution of such contacts are revealed.

Concept, hardware development, and clinical trials of a Galinstan based Mercury free sphygmomanometer: Merkfree

The aim of this work is to develop Merkfree—a mercury-free sphygmomanometer that looks, feels, and operates just like a traditional mercury sphygmomanometer (MS). For this we use Galinstan as a substitute for mercury, which is a non-toxic alloy of Gallium, Indium and Tin. Galinstan is nearly half as dense as mercury and sticks to class. To work with the lower density, we designed an enclosure and scale that is nearly double the length of MS. The issue of stickiness with glass was resolved by maintaining a small meniscus of a reducing agent in the measuring tube and tank of Merkfree. Clinical trials to validate the accuracy of Merkfree against MS and oscillometric sphygmomanometer (OS) were conducted over 252 patients. The results show a good correlation of the systolic and diastolic BP measurements from Merkfree with respect to MS and the OS. The mean absolute percentage error is less than 10% for both SBP and DBP. We also found that Merkfree has lower rounding-off errors compared to MS. Merkfree can be a viable alternative to mercury sphygmomanometer that can help achieve the goal of WHO in eliminating mercury from healthcare, while simultaneously making sure that gold standard technique of sphygmomanometry continues to be available to the clinicians.

Correlated Study of Material Interaction Between Capillary Printed Eutectic Gallium Alloys and Gold Electrodes.

Liquid metals (LMs) play a growing role in flexible electronics and connected applications. Here, LMs come into direct contact with metal electrodes thus allowing for corrosion and additional alloying, potentially compromising device stability. Nevertheless, comprehensive studies on the interfacial interaction of the materials are still sparse. Therefore, a correlated material interaction study of capillary-printed Galinstan (eutetic alloy of Ga/In/Sn) with gold surfaces and electrodes is conducted. Comprehensive application of optical microscopy, vertical scanning interferometry, scanning electron microscopy/spectroscopy, x-ray photon spectroscopy, and atomic force microscopy allow for an in depth characterization of the spreading process of LM lines on gold films, revealing the differential spread of the different LM components and the formation of intermetallic nanostructures on the surface of the surrounding gold film. A model for the growth process based on the penetration of LM along the gold film grain boundaries is proposed based on the obtained time-dependent characterization. The distribution of gold, Galinstan, and intermetallic phases in a gold wire dipped into LM is observed using X-ray nano tomography as a complementary view on the internal nanostructure. Finally, resistance measurements on LM lines connecting gold electrodes over time allow to estimate the influence on the material interaction on electronic applications.

Structure Transformations and Supercooling in Nanostructured Gallium Alloys

Structure Transformations and Supercooling in Nanostructured Gallium Alloys

Imbibition-induced selective wetting of liquid metal

Herein, we present the imbibition-induced, spontaneous, and selective wetting characteristics of gallium-based liquid metal alloys on a metallized surface with micro-scale topographical features. Gallium-based liquid metal alloys are fascinating materials that have enormous surface tension; therefore, they are difficult to pattern into films. The complete wetting of eutectic alloy of gallium and indium is realized on microstructured copper surfaces in the presence of HCl vapor, which removes the native oxide from the liquid metal alloy. This wetting is numerically explained based on the Wenzel’s model and imbibition process, revealing that the dimensions of the microstructures are critical for effective imbibition-driven wetting of the liquid metal. Further, we demonstrate that the spontaneous wetting of the liquid metal can be directed selectively along the microstructured region on the metallic surface to create patterns. This simple process enables the uniform coating and patterning of the liquid metal over large areas without an external force or complex processing. We demonstrate that the liquid metal-patterned substrates maintain electrical connection even in a stretched state and after repetitive stretching cycles.

First-Principles Study on the Adsorption Behavior of O2 on the Surface of Plutonium Gallium System.

To deeply understand the adsorption process of oxygen on the surface of a plutonium gallium system and to reveal the chemical reaction mechanism at the initial stage of oxidative corrosion on the surface of plutonium gallium alloy at a theoretical level, the adsorption behavior of oxygen molecules on the surface of a plutonium gallium system was investigated by a first-principles approach based on density flooding theory. The results show that the molecular bond length increases and finally breaks when the surface oxygen molecule is adsorbed on the surface of plutonium gallium system and dissociates into two atomic states. The most likely adsorption position of oxygen molecules on the surface of plutonium gallium system is hole-site vertical adsorption with the adsorption energy size of 10.7 eV. The bonding between oxygen atom and surface is mainly due to the overlapping hybridization of Pu-6s, Pu-7s, Pu-6d, Ga-3d and O-2p orbitals. Oxygen molecules mainly interact with the atoms of the first layer on the surface of the plutonium gallium system. The oxygen atoms after stable adsorption are able to diffuse to the subsurface of the plutonium gallium system after overcoming the energy barrier of 16.7 eV and form a stable structure. The research results reveal the initial reaction process and adsorption law of oxygen on the surface of plutonium gallium system from microscopic level, which is helpful to further explore the surface corrosion prevention technology of plutonium gallium system and improve the reliability and safety of plutonium gallium alloy components.