Ga-based Alloys Research Articles

Conversion of CO2 into fibrous carbon materials using Ga-based liquid alloys

This study investigates the catalytic reduction of CO2 using various ratios of Ga-based liquid alloys under different conditions. We explored the alloying of liquid gallium with metals like indium (In) and magnesium (Mg) through mechanical stirring and heating. The alloys, once prepared, were exposed to CO2 in a reactor, with the Ga-In-Mg alloy demonstrating optimal reaction effects. In an exemplary synthesis, 1 g of Ga was combined with 30 wt% In and 7 wt% Mg, yielding a 7 wt% Ga-In-Mg alloy. This alloy, when reacted with CO2 for 10 h, exhibited a maximum weight gain of 445 mg. Elemental analysis showed a carbon content increase from 4.56 % to 72.56 % post-reaction. The reacted alloy, post-acid washing and electron microscopy examination, revealed the production of fibrous carbon materials approximately 7 μm wide. The primary objectives of this research were to identify the optimal temperature for CO2 reduction by the alloy and to determine the most efficient alloy catalyst using orthogonal experimental methods. Furthermore, we aimed to elucidate the catalytic mechanism of gallium-based liquid metal in CO2 reduction. The study also involved analyzing the adsorption and reaction processes by fitting the adsorption and reaction kinetic curves of the liquid metal with CO2. Achieving these objectives could enable the conversion of CO2 into solid carbon products, aligning with current environmental and sustainable development goals. This research offers new insights and innovative approaches to tackling energy-related challenges, highlighting the potential of liquid metal alloys in carbon capture and reduction applications.

Recent Advances in Liquid Metals for Rechargeable Batteries

AbstractLiquid metals (LMs) with their unique properties are considered for a range of applications such as energy storage, catalysis, electronics, and biomedical engineering. Recently, the introduction of LMs into rechargeable batteries has not only proven to improve overall performance but also overcome commonly known challenges like low energy density, material degradation, interface failure, and poor system integrity. Specifically, room‐temperature LMs such as gallium (Ga), Ga‐based alloys (GBAs), and metallic mercury (Hg) are promising candidates in rechargeable batteries due to their low viscosity, high electrical and thermal conductivity, excellent deformability, superior electrochemical properties, and self‐healing capability. Herein, a review of recent advances in LMs for rechargeable batteries, starting with a brief introduction to LMs fundamentals and their properties is presented. Then, an extensive literature review is carried out to summarize the LMs’ advances in addressing existing challenges of lithium‐ion, lithium‐metal, lithium–sulfur, and other rechargeable batteries. The current state of the art and future perspective are also put forward. It is believed that highlighting potential developments pertaining to LMs can fascinate researchers in exploring them for future rechargeable batteries.

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.

Study of the Electrochemical and Self-healing Processes of Galinstan as an Anode Material for Li-ion Batteries

Alloy electrodes are attracting a lot of interest in the field of Li-ion batteries due to their high energy density. However, they suffer from large volume expansion and contraction during lithiation and delithiation, leading to rapid pulverization and disconnection. A strategy to avoid this is to use self-healing materials. Ga-based liquid alloys have been studied as self-healing electrodes because of their capacity to store Li and their liquid state at room temperature. The so-called “galinstan” (Ga0.77In0.15Sn0.08) exhibits the lowest melting temperatures and has also been used to add self-healing properties in composite electrodes. Nevertheless, its lithiation mechanism and its practical capacity still remain unknown. Also, the reversibility of the lithiation, which is crucial to ensure the self-healing properties offered by the liquid metal, requires investigation. In this work, electrochemical measurements were coupled with XRD and SEM analyses to better understand the redox processes, structural and morphological properties of galinstan as an electrode material in Li-ion batteries. It was shown that only Ga and In would react with Li to form LiGa and LiIn. The reversibility of these reactions and thus the self-healing ability of galinstan was demonstrated through observation of its liquid state before and after electrochemical cycling.

Transient liquid phase bonding with Ga-based alloys for electronics interconnections

Significant demands on electronics packaging are driven by miniaturization, energy efficiency, high performance, and minimal carbon footprint. Liquid Ga and Ga-based alloys as interconnect materials exhibit a great potential in these applications due to the benefits including low melting points, non-toxicity, and stable high melting point intermetallic compounds (IMCs) formed with other metals such as Cu. Taking advantages of transient liquid phase bonding (TLPB) technology, the uses of Ga-based alloys can be attractive as a more efficient and environmentally friendly method for interconnections. This study aims to address the technical challenges in the applications of Ga and Ga-based alloys for Cu bonding through the TLPB process. These include solderability of Ga-based solders on Cu, interfacial reactions during bonding, as well as the microstructure and properties of the resultant joints. In addition, the porosity and shear strength of the joints have been evaluated for better understanding of the reliability of the joints. The results show that Ga-based solders present an acceptable solderability given their wetting behavior observed. The constituent of the resultant joints consists of θ − CuGa2 and γ3 − Cu9Ga4 IMC phases as identified, which are formed as the results of interfacial reactions between liquid Ga-based alloys and Cu substrate. Indium, as an alloying element in the solders, has been found to be able to accelerate γ3 − Cu9Ga4 formation and reduce the porosity in the joints. It is also found that the pressure applied during TLPB also helps the reduction of porosity, as well as the increase of mechanical strength of the joints. These results provided not only new insight into the mechanism of the interfacial reaction between Ga-based liquid metals (GLMs) and solid Cu systems, but also a new manufacturing route for electronics integration.

Design and Synthesis of Cobalt-Based Hollow Nanoparticles through the Liquid Metal Template.

Co-based compounds have attracted much attention due to their competitive catalytic activities. To enhance their intrinsic electrocatalytic activity, morphology engineering is one of the effective strategies. Hollow structures have fascinating properties due to their low density and high loading capacity. In this work, we introduce a Ga-based liquid alloy as a reactive template for the synthesis of varying Co-based hollow nanoparticles. The fluidity character of the Ga-based liquid alloy facilitates the large-scale production of nanoparticles via a top-down shearing process. The pre-installed active species (here is Zn) in the liquid alloy serve as a sacrificial source to quantitatively reduce Co2+ ions and form Co-based compounds. Well-structured Ga/CoOOH core-shell nanospheres are thus successfully prepared, and more varied Co-based hollow nanoparticles can be obtained by post-treatment and reaction. Hollow structures can offer enhanced interfacial area and increased active sites, benefiting the catalytic performance. Among the prepared Co-based catalysts, CoSe2 hollow nanoparticles exhibited the best oxygen evolution reaction (OER) activity with an overpotential of 340 mV at the current density of 10 mA/cm2. This work provides a novel strategy for the rational design and simple preparation of hollow nanoparticles.

Modulating the Reactivity of Liquid Ga Nanoparticle Inks by Modifying Their Surface Chemistry.

Micro- and nanosized particles of liquid metals, particularly Ga-based alloys, are attracting increasing attention for applications in several fields. The surface functionalization of Ga-based nanoparticles (NPs) with organic ligands renders easily processable inks. However, little is known about the interaction of these molecules with the native oxide skin, which regulates many properties of liquid metal NPs. Here, we investigate the impact of selected capping ligands on the native oxide thickness of Ga NPs and on their chemical reactivity, choosing the galvanic replacement reaction (GRR) as one example. We demonstrate that amines and carboxylic acids promote thicker oxide shells while thiols and phosphines hinder the oxide growth. Upon pondering thermodynamics and kinetics factors, we conclude the affinity of the anchoring group toward the metal core being the major driver in determining the oxide thickness. We go on to prove that thicker shells foster the formation of Cu-Ga nanodimers following the reaction of the Ga NPs with a copper-amine complex. In contrast, thinner oxides lead to formation of isolated Cu NPs. This study reveals the importance of the choice of ligand when studying Ga-based metal NPs for different applications since both their surface chemistry and reactivity are largely affected by this decision.

Fe–Mn–Ga shape memory glass-coated microwire with sensing possibilities

The structural phase transformation in a non-stoichiometric shape memory Fe42.8Mn27.6Ga29.6 Heusler glass-coated microwire was experimentally observed using indirect magnetic, permeability, and electrical resistance measurements. While the temperature dependence of magnetization revealed hysteresis of magnetization during the heating and cooling process, magnetic hysteresis loops point to the change in the direction of the easy magnetization axis of the low- and high-temperature phase. Additionally, the unusual behavior of the permeability and electrical resistance measurements are in good agreement with the magnetic measurements. The x-ray diffraction profile measured at room temperature revealed the coexistence of a high-temperature L21 phase (a= 5.88 Å) and low-temperature phase with the L12 structure (a = 3.71 Å) and can be considered as another proof of the shape memory effect that is expected in the Fe–Mn–Ga-based Heusler alloys. In the presented glass-coated microwire, it is not only possible to shift the transformation temperature with the external magnetic field, but from its initial permeability value, it is possible to determine whether the alloy has undergone the structural transformation. Therefore, the presented Fe–Mn–Ga-based glass-coated microwire may be considered a suitable candidate for microactuators with sensory capabilities.

Insight into the effect of reorganized chemical short-range orders at Ga-based alloys/Cu interfaces on the nucleation and growth of CuGa2 crystals

The present work verified that the presence of pristine chemical short-range orders (CSROs) in both pure Ga and Ga-based alloys at 180 ℃ has no significant influence on the microstructure evolution of bricks-like CuGa2. Due to its low mixed enthalpy of Cu-Ga atomic pairs that facilitates some preferential self-assembled inter- atomic neighborhoods, the diffused Cu atoms destroyed the primitive CRSOs in liquid alloys and thus promoted the reorganization of broken or dissolved pristine CRSOs, which determined the nucleation and growth of CuGa2. The estimated electrical resistivity of CuGa2 is 171.4 times that of pure Cu, indicating that the chemical reaction between Cu and Ga atoms may cause the electrical properties degradation. This study may contribute to design and fabricate soft and wearable electronics with high performance in which low melting point Ga-based alloys are employed.

Insight into the interatomic competitive mechanism for interfacial stability of room temperature liquid GaInSn/Cu electrode

Room temperature Ga-based alloys have received more and more attentions due to their unique advantages in these applications of stretchable and wearable electronics. In this paper, the interfacial stability of liquid GaInSn/Cu interface was systematically investigated. From the perspective of crystallography, the orientation relationship between the nucleation and growth of intermetallic compounds and Cu substrate are discussed according to plane-on-plane matching model and edge-to-edge matching model. The required standard formation enthalpy and bond enthalpy of as-formed intermetallic compounds are estimated based on the elemental condensed bond enthalpy and crystal cluster theory. For the ternary GaInSn system, the competitive reactive mechanism between different reactive atomic pairs was revealed and discussed from the thermodynamic view, which verified that the rationality of the formed intermetallic compounds only consisting of Cu and Ga. Besides, we confirmed that the wetting behavior of GaInSn on Cu substrate was determined by the affinity and close contact probability of different atomic pairs. • Atomic competitive mechanism of Cu–Ga, Cu–In, Cu–Sn atomic pairs is revealed. • Growth of CuGa 2 was analyzed from thermodynamic and crystallographic view. • Wetting behavior is determined by the affinity and close contact probability of atomic pairs. • Orientation relationship is defined according to plane-on-plane matching and edge-to-edge matching models. • Interfacial stability of GaInSn/Cu are destroyed during room temperature long-term service.

Pronounced electromigration of GaInSn/Cu interconnects under super low critical current density

Ga-based alloys has been paid increasingly attention as a promising material choice for constructing flexible and stretchable electronics. The interfacial stability of non-bonding GaInSn/Cu interconnect plays a critical role in determining its electrical performance. Here, we report an interesting electromigration phenomenon under current flux and verify the atoms migration through the GaInSn path from cathode to the anode. The critical current density for inducing the room temperature electromigration of Cu/GaInSn/Cu is two orders of magnitude lower than that of other electromigration system. When Ni which has a higher bond strength is employed to substitute Cu anode, due to the small number of intermetallic compounds embryos, the electromigration resistance of anode material is substantially improved. Our findings will provide good insights into the electromigration of Cu/GaInSn/Cu and may offer a critical first step toward the design of high- performance Ga-based soft and stretchable electronics.

Hysteretic structural changes within five-layered modulated 10M martensite of Ni–Mn–Ga(–Fe)

Modulated structure of Ni–Mn–Ga-based alloys is decisive in their magnetic shape memory (MSM) functionality. However, the precise nature of their five-layered modulated 10M martensite is still an open question. We used x-ray and neutron diffraction experiments on single crystals to investigate structural changes within 10M-modulated martensite of the Ni50Mn27Ga22Fe1 MSM alloy. The modulation vector gradually increases upon cooling from commensurate q = (2/5) g 110, where g 110 is the reciprocal lattice vector, to incommensurate with q up to pseudo-commensurate q = (3/7) g 110. Upon heating, reverse changes are observed with a thermal hysteresis of ≈60 K. The same hysteretic behaviour was detected in the electrical resistivity and the effective elastic modulus. Scanning electron microscopy showed that the changes are accompanied by the refinement of the a/b laminate. These observations indicate that the commensurate state is a metastable form of 10M martensite. Upon cooling, this phase evolves through nanotwinning into a more irregular and more stable incommensurate structure.

Interfacial reactions between Ga and Cu-xNi (x=0, 2, 6, 10, 14) substrates and the strength of Cu-xNi/Ga/Cu-xNi joints

There is potential for using Ga and Ga-based alloys as low temperature bonding materials in electronic packaging. This study investigates the interfacial reactions between liquid Ga and Cu-xNi (x = 0, 2, 6, 10, 14 wt%) substrates at room temperature using Synchrotron X-ray powder diffraction and analytical scanning/transmission electron microscopy, and subsequently examines the lap shear strength of these joints. The concentration of Ni in the substrate has a strong effect on both the type of intermetallics that form and their rate of growth. Mechanisms of intermetallic growth and the strength of the joints fabricated with the Cu-xNi substrates are discussed along with the crystallography of the intermetallics and methods of joining.

Self-healing gallium phosphide embedded in a hybrid matrix for high-performance Li-ion batteries

Self-healing materials have recently received considerable attention for improving the Li storage in anodes with high theoretical capacity that suffer from the mechanical instability triggered by the large volume change that occurs during electrochemical reactions. Ga has recently been explored for self-healing liquid metal electrodes in Li-ion batteries because it can be melted near room temperature. Previous reports have demonstrated the ultra-long cycling stability of these Ga-based electrodes owing to their self-healing properties. Unfortunately, despite these efforts, the performance of these Ga-based self-healing electrodes have not been fully satisfactory, particularly in terms of capacity. More importantly, the self-healing mechanism of liquid Ga has not been clearly investigated. Here, we synthesized GaP as a novel self-healing anode with an ultra-high capacity and stability. Self-healing in this Ga-based alloy occurred via the liquid-solid-liquid transition of Ga during lithiation/delithiation. In addition, by confining the liquid Ga in an appropriate binder (poly(acrylic acid)) through strong hydrogen bonding, stable cyclic behavior of the GaP was achieved. Furthermore, the TiO2-C hybrid matrix promoted the mechanical integrity and electrical conductivity of the GaP (GaP@TiO2-C). Consequently, the GaP@TiO2-C electrode showed superb cyclic performance (1012.0 mAh g−1 at 0.5 A g−1 after 500 cycles) and great rate capability. Various post-mortem analyses, including X-ray diffraction, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy, revealed the in-depth electrochemical reaction and self-healing mechanism of the GaP electrode. This study provides insight into the development of self-healing electrodes with high capacities and long cycling stabilities.

Liquid Metals in Catalysis for Energy Applications

Summary To keep up with the fast-paced transitioning of the global energy sector, which is constantly thriving to enable reliable, economic, and sustainable energy production, catalysis research has been required to continuously evolve in response. The challenges in the existing systems are predominantly due to dependencies on heterogeneous solid catalysts that are susceptible to coking. In this respect, liquid-metal (LM) catalysts have been demonstrated to have a critical advantage over conventional catalysts. Recently, LMs acquired a place in catalysis, with a reputation often synonymous with interesting properties and a remarkable ability to break trade-offs between homogeneous and heterogeneous catalysis. This review bridges the fundamental principles of LM research and the recent advances in LM-based thermal and electrochemical catalysis for energy applications. Moreover, emerging approaches for the improved utilization of LMs are outlined, and the concepts requiring greater research attention that could enable the development of exciting energy solutions are highlighted.

Pulsing Liquid Alloys for Nanomaterials Synthesis.

Although it remains unexplored, the direct synthesis and expulsion of metals from alloys can offer many opportunities. Here, such a phenomenon is realized electrochemically by applying a polarizing voltage signal to liquid alloys. The signal induces an abrupt interfacial perturbation at the Ga-based liquid alloy surface and results in an unrestrained discharge of minority elements, such as Sn, In, and Zn, from the liquid alloy. We show that this can occur by either changing the surface tension or inducing a reversible redox reaction at the alloys' interface. The expelled metals exhibit nanosized and porous morphologies, and depending on the cell electrochemistry, these metals can be passivated with oxide layers or fully oxidized into distinct nanostructures. The proposed concept of metal expulsion from liquid alloys can be extended to a wide variety of molten metals for producing metallic and metallic compound nanostructures for advanced applications.

Intermetallic formation mechanisms and properties in room-temperature Ga soldering

Ga and Ga-based alloys have received significant attention due to their potential applications as liquid metals and also for low temperature, or even room temperature, bonding in microelectronics. This study investigates the effect of In and Sn on the interfacial reactions between eutectic Ga-based alloys and Cu substrates at room temperature. The interfacial microstructures are characterised by electron microscopy and Synchrotron powder x-ray diffraction. In-situ heating observations are carried out to verify the thermal expansion properties of the intermetallic compounds formed with In and/or Sn additions in the Ga-based alloy/Cu reactions. The alloying elements are found to decrease the coefficient of thermal expansion of CuGa2 as the temperature increases. In and Sn are also examined with respect to their influence on the wettability of Ga-based alloys on Cu substrates under an argon atmosphere. The results are important to consider in the development of bonding processes involving Ga and Ga alloys.

Properties of CuGa2 Formed Between Liquid Ga and Cu Substrates at Room Temperature

Ga and Ga-based alloys have received significant attention due to their potential application in the liquid state for low-temperature bonding in microelectronics. This study investigated the interfacial reactions between liquid Ga and pure Cu substrates at room temperature. The directional thermal expansion behaviour of the resulting CuGa2 was analysed by synchrotron x-ray powder diffraction with supporting observations of single crystal foils in high-voltage transmission electron microscopy. The mechanical properties of CuGa2 were evaluated by nano-indentation. CuGa2 was found to have advantages over other intermetallics that are present in assemblies made with current generation lead-free solders, including Ag3Sn, Cu6Sn5 and Cu3Sn. In addition to enabling lower process temperatures, solder alloys that form CuGa2 at the interface with Cu offer the possibility of providing more reliable connections in the very small joints that play an increasingly important role as the trend to miniaturisation of electronics continues.

Temperature-induced atomic structural evolution in a liquid Ga-based alloy

The atomic-scale structural evolution of Ga68.5In21·5Sn10 (wt. %) liquid alloy has been explored utilizing in-situ high-energy synchrotron X-ray diffraction from room temperature (293 K) to around the melting point. During the process of decreasing temperature, bond lengths of dominant atomic pairs decrease, whereas the total coordination numbers of the first nearest neighbor shell increase. This structural transition is ascribed to the redistribution of atoms and/or clusters and the decrease of vacancies induced by decreasing temperature. Our results are supportive for further understanding the atomic-scale structural evolution of liquid alloys at the low-temperature condition.

Effects of Ni and Cu Antisite Substitution on the Phase Stability of CuGa2 from Liquid Ga/Cu–Ni Interfacial Reaction

Ga and Ga-based alloys have received significant attention for applications in the liquid state and also for their potential as a bonding material in microelectronic assemblies. This study investigates the phase stability of the CuGa2 phase as a product of the interfacial reaction between liquid Ga and Cu-10Ni substrates at room temperature. In the binary Ga-Cu system, CuGa2 is decomposed into liquid Ga and Cu9Ga4 as the temperature increases to around 260 °C, which prevents the widespread application of this alloy. In contrast to CuGa2 grown from a pure Cu substrate, CuGa2 from the Cu-10Ni substrate shows an increase in the decomposition temperature during heating from 25 to 300 °C. According to our first-principle calculations, there is only a minor difference in the total free energy between Ni solute at the Cu sublattice and the Ga sublattice in the tetragonal CuGa2 crystal structure. This result indicates that both of the sublattices can accommodate the dilute Ni solute with comparable probability. Regardless of the sublattice where the Ni impurities are located, the presence of diluted Ni in the matrix stabilizes the CuGa2 system by inducing some localized Ni 3d states at energy levels near the Fermi level. It is also shown that the formation of Cu antisite defects, which also stabilizes CuGa2, is preferable if the CuGa2 matrix is grown on a Ni-containing substrate.