Surface Of Liquid Alloys Research Articles

Sub-5 nm ultrathin IGO film transistor printed by micro-doped InGa liquid alloy

In this study, we introduce a novel perspective that the formation of the atomically ultrathin oxide layer on the surface of liquid alloys is primarily governed by thermodynamic laws and is additionally influenced by the surface tension of the liquid alloys. In this case, we control the competition of Gibbs free energy and surface tension to effectively address the severe segregation problem of Ga2O3 and realize the precise doping of Ga2O3 in the preparation process of two dimensional IGO film through the liquid InGa alloy printing approach. Importantly, the Ga2O3 content in the IGO films can be tailored in the full range and a sub-5 nm ultrathin IGO film transistor is innovatively fabricated. The oxidation law, band gap, Fermi level, field-effect mobility, subthreshold swing, and other properties of IGO films in sub-5 nm scale are systemically investigated in detail. It has been demonstrated that the incorporation of Ga2O3 in the doping process dramatically reduced the device's turn-off current and enhanced its ability to resist ultraviolet interference. This novel doping process opens up a significant opportunity for future developments of atomically ultrathin transparent conducting film.

Temperature and chemical effects on the interfacial energy between a Ga-In-Sn eutectic liquid alloy and nanoscopic asperities.

The interfacial energies between a eutectic Ga–In–Sn liquid alloy and single nanoscopic asperities of SiOx, Au, and PtSi have been determined in the temperature range between room temperature and 90 °C by atomic force spectroscopy. For all asperities used here, we find that the interfacial tension of the eutectic Ga–In–Sn liquid alloy is smaller than its free surface energy by a factor of two (for SiOx) to eight (for PtSi). Any significant oxide growth upon heating studied was not detected here, and the measured interfacial energies strongly depend on the chemistry of the asperities. We also observe a weak increase of the interfacial energy as a function of the temperature, which can be explained by the reactivity between SiOx and Ga and the occurrence of chemical segregation at the liquid alloy surface.

Temperature-dependent XPS studies on Ga-In alloys through the melting-point

Gallium indium alloys are known to be liquid at remarkably low temperatures. Herein, we provide X-ray photoelectron spectroscopy (XPS) studies and DFT-based ab-initio molecular dynamics (MD) calculations on the composition of the liquid alloy surface. We find that alloying Ga and In in ratios close to the eutectic composition results in only minor signal shifts of the corresponding In core levels. The topmost surface layer of the liquid alloy exhibits significant In enrichment for all measured temperatures, between 300 K to 800 K the observed enrichment slightly decreases with increasing temperature. This behavior is seen in both temperature-dependent XPS and ab-initio MD simulations. Furthermore, we investigate changes in the surface composition during the liquid-to-solid phase transition by time-dependent XPS during cooling of the alloy sample. The surface of the alloy presents an advantageous nucleation site, where we regularly observe the precipitation of indium. During cooling, the precipitation processes were followed by both XPS and by monitoring the sample temperature/heating power.

Exploration of Sn70Li30 alloy as possible material for flowing liquid metal plasma facing components

• First wetting data for Sn 70 Li 30 alloy are reported on 316 SS, Mo and W substrates. • Wetting temperatures of 360 °C, 390 °C and 405 °C were measured respectively. • Alloy contamination/passivation worsened wettability with Δ T~130 °C in worst cases. • First depth profile characterization of the tin-lithium alloy by SIMS-ToF was carried out. • Mixing boundaries between alloy and substrates studied by SEM/EDS and 3D microscopy. • Lithium and tin induced corrosion found on 316 SS exposed at T < 550 °C during t ≤ 3 h. • Molybdenum and tungsten presented good compatibility after equivalent interaction. As an advanced alternative to solid materials, Liquid Metals (LM) may offer more resilient and feasible Plasma Facing Components (PFCs). Particularly, regarding the unavoidable material erosion/degradation produced by particle/heat fluxes in future fusion devices where much longer duty cycles are expected. Furthermore, configurations that propose a flowing LM surface can add the advantage of a continuously fresh and clean layer facing the plasma. Although lithium is the most widely tested option, tin-lithium (SnLi) alloys have been proposed to attempt to combine the positive characteristics of both pure elements and ameliorate the specific issues of lithium. In this work, the potential use of Sn 70 Li 30 alloy in such flowing concepts has been explored by addressing several preliminary and mandatory aspects for its utilization. Key issues such as wettability and compatibility of the alloy with relevant substrates have been studied in a multidisciplinary approach. The data obtained from deposited liquid tin-lithium droplets indicates approximate wetting temperatures of 360 °C, 390 °C and 405 °C for the fresh alloy on 316 stainless steel, molybdenum, and tungsten, respectively. However, the alloy contamination appeared to strongly affect the wetting characteristics of materials, increasing their wetting temperature by ~130 °C in the worst observed cases. Interestingly, in some instances, the instability of the liquid alloy surface was observed in the form of sudden gaseous ejection. The deposited droplets were posteriorly characterized in terms of absolute composition and depth profile by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) and Secondary Ion Mass Spectrometry (SIMS-ToF). Additionally, the nature and composition of the boundaries between the substrates and alloy microparticles was investigated by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), and 3D Laser microscopy. The overall results of this post-mortem characterization revealed that first signs of corrosion induced by both alloy elements (lithium-chromium association and iron-tin intermetallic mixing) were present on 316 stainless steel after short exposures (≤3 h) at temperatures lower than 550 °C. Conversely, molybdenum and tungsten showed good compatibility with the alloy in equivalent conditions. The global implications of these results are finally addressed, focusing on the future perspectives and the more viable scenarios for the eventual utilization of these alloys in flowing liquid metal configurations.

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.

Important Thermodynamic Parameters of Lithium–Tin Alloys from the Point of View of Their Use in Tokamaks

Along with other liquid metals, lithium–tin alloys are considered an alternative to the use of solid materials in the development of plasma-facing intrachamber components for future fusion reactors. The possibility of the practical use of these alloys in tokamaks is determined by their thermodynamic parameters, their ability to retain hydrogen isotopes in the melt, and the properties that determine the principles by which hydrogen isotopes can be extracted from a liquid Li–Sn alloy. The Sieverts’ constants for dilute hydrogen solutions in the melts of this system are calculated with the use of equations of the coordination-cluster model. The results of theoretical calculations are compared with previously published experimental data for two alloys of the Li–Sn system. A calculation method based on the use of the Butler equation, together with the experimentally obtained concentration dependences of the thermodynamic potentials of the components of this binary system, is applied to find the composition of the liquid-alloy surface.

Melting of Grey Cast Iron Based on Steel Scrap Using Silicon Carbide

Abstract The paper presents the issue of synthetic cast iron production in the electric induction furnace exclusively on the steel scrap base. Silicon carbide and synthetic graphite were used as carburizers. The carburizers were introduced with solid charge or added on the liquid metal surface. The chemical analysis of the produced cast iron, the carburization efficiency and microstructure features were presented in the paper. It was stated that ferrosilicon can be replaced by silicon carbide during the synthetic cast iron melting process. However, due to its chemical composition (30% C and 70% Si) which causes significant silicon content in iron increase, the carbon deficit can be partly compensated by the carburizer introduction. Moreover it was shown that the best carbon and silicon assimilation rate is obtained where the silicon carbide is being introduced together with solid charge. When it is thrown onto liquid alloy surface the efficiency of the process is almost two times less and the melting process lasts dozen minutes long. The microstructure of the cast iron produced with the silicon carbide shows more bulky graphite flakes than inside the microstructure of cast iron produced on the pig iron base.

Theoretical and Practical Aspects of Pneumatic Powder Injection into Liquid Alloys with a Non-Submerged Lance

Abstract The method of powder injection into molten metal has been widely known since tens of years and successfully utilized in various metallurgical processes. The most common is a solution with injection lance submerged under the liquid alloy surface, because it is easier apart from some of disadvantages of this approach. In this paper the authors’ complex experiments on the pneumatic injection process with non-submerged lance have been presented. The new approach on jet cone angle importance and its influence on the efficiency of the injection process has been shown. The issue of the effective jet radius that was proposed by former scientists as well as computer modelling and injection experiments recorded with high speed camera have been presented. The final comparison of the typical injection lance and developed by authors new lance with flange was presented, too. The benefits of use of a new one for the treatment of small liquid alloy volume (e.g. inoculation or alloys addition introduction) have been pointed.

Size effect on surface tension of liquid binary alloy droplets

A simple model for size-dependent surface tension of liquid binary alloy droplets has been established based on Bulter’s equation and our model for size-dependent surface tension of pure liquid component. As an example, the surface tension of liquid Bi–Sn alloy droplets are calculated and discussed. The results show that as the size of the liquid alloy droplets decreases, the corresponding surface tension decreases. The component with lower surface tension is enriched in the surface layer at all times while relatively more another component with higher surface tension appear in the surface region when the size decreases. The effect of decreasing size on liquid alloy surface tension is like that of increasing temperature. When size is larger than about 12 nm, the size effect is small and negligible.

Surface Properties of Ag-Cu-Zr Liquid Alloys in Relation to the Wettability of Boride Ceramics

The wetting phenomena and adhesion between Ag-Cu-Zr molten alloys (where Zr is an active brazing element) and ZrB2-ceramic substrate have been investigated from theoretical and experimental point of view. The wetting phenomena of molten alloy/ceramic substrate depend on the bonding characteristics of liquid alloys and ceramics as well as the magnitude of interactive forces at the interface. Accordingly, the first step of this investigation is to determine the surface properties of Ag-Cu, Ag-Zr and Cu-Zr liquid alloys. The energetics of the bulk and the surface of liquid alloys have been analysed in the framework of statistical mechanical theory in conjunction with Quasi-Lattice Theory (QLT), through the study of the concentration dependence of various properties such as surface tension, surface composition, concentration fluctuations in the long wavelength limit and Warren-Cowley chemical short-range order parameter. Combining the Young and the Dupré equations, the obtained values of surface tension together with contact angle data have been used to calculate the work of adhesion.

Structure of the liquid-vapor interface of a dilute ternary alloy: Pb and Sn in Ga

We report the results of grazing incidence x-ray diffraction and x-ray reflectivity studies of the liquid-vapor interfaces of three dilute ternary alloys, composed of a small constant amount of Pb (0.072 at. %) and a small variable amount of Sn (0.12, 3.4, and 7.7 at. %) dissolved in Ga. The solutes Pb and Sn compete to segregate in the liquid-vapor interfaces of these alloys; in each case, over the temperature range studied (30--120 \ifmmode^\circ\else\textdegree\fi{}C), the composition of the outermost layer of the interface is dominated by excess Pb. In the case of the alloy with Sn concentration of 0.12 at. %, the excess Pb in the liquid-vapor interface forms a crystalline monolayer that melts at 67.8 \ifmmode^\circ\else\textdegree\fi{}C. In the case of the alloy with Sn concentration of 3.4 at. %, the excess Pb in the liquid-vapor interface again forms a crystalline monolayer, but that crystalline monolayer melts at 40.5 \ifmmode^\circ\else\textdegree\fi{}C. In the case of the alloy with Sn concentration of 7.7 at. %, the excess Pb in the liquid-vapor interface forms a two-dimensional liquid over the entire accessible temperature range. When the excess Pb in the liquid-vapor interface forms a two-dimensional crystal, it fully covers the surface of the liquid; at higher temperatures, when the Pb monolayer is liquid, it only partially covers the liquid alloy surface, with the remainder covered by a partial monolayer of liquid Sn. Two-dimensional liquid Pb and two-dimensional liquid Sn appear to be immiscible under the conditions of our experiments. In the case of the sample with the smallest concentration of Sn, the correlation length obtained from the width of the diffraction peak drops almost discontinuously at 67.8 \ifmmode^\circ\else\textdegree\fi{}C to a smaller value. It then further decreases continuously until about 90 \ifmmode^\circ\else\textdegree\fi{}C, thereafter becoming constant. These data suggest the existence of an intermediate disordered phase stable between 67.8 and 90 \ifmmode^\circ\else\textdegree\fi{}C. Our experiments fall short of providing unambiguous evidence for the existence and character of this disordered phase. We speculate that between 67.8 and about 90 \ifmmode^\circ\else\textdegree\fi{}C the Pb monolayer has a hexatic structure and that above 90 \ifmmode^\circ\else\textdegree\fi{}C it is liquid, as is implied by the results of recent simulations of the temperature dependence of the structure of a quasi-two-dimensional layer of Pb.

Pairing interactions and Gibbs adsorption at the liquid bi-in surface: a resonant X-ray reflectivity study.

Resonant x-ray reflectivity measurements from the surface of liquid Bi(22)In(78) find only a modest surface Bi enhancement, with 35 at. % Bi in the first atomic layer. This is in contrast to the Gibbs adsorption in all liquid alloys studied to date, which show surface segregation of a complete monolayer of the low surface tension component. This suggests that surface adsorption in Bi-In is dominated by attractive interactions that increase the number of Bi-In neighbors at the surface. These are the first measurements in which resonant x-ray scattering has been used to quantify compositional changes induced at a liquid alloy surface.

Loss of material from liquid metal collector surfaces during sputter deposition of gold

We have investigated the loss of both sputtered atoms and substrate atoms from liquid Ga-In alloy collector surfaces exposed to sputtered Au by analyzing the composition and angular distribution of material deposited on a graphite collector surrounding the alloy. Ga, In and Au atoms were all detected on the graphite collector. The angular distribution of Au was strongly peaked toward the surface normal of the alloy collector, consistent with specular reflection of Au atoms incident on the alloy surface. The presence of In and Ga on the graphite surface indicates that sputtering of the alloy collector surface occurs during sputter deposition. The broad angular distributions obtained for these elements are consistent with this conclusion. Deposited Au was not subject to resputtering because it did not remain on the liquid alloy surface after deposition. Our results suggest that, for more conventional solid collectors, resputtering of deposited material and direct reflection of incident atoms are both significant mechanisms for the loss of material and the redistribution of material during sputter deposition. Re-examination of the results of many collection-type sputtering experiments should be considered in the light of these results.

Production and assessment of direct cast soft magnetic alloy strips

The melt overflow process has been developed as a technique to produce tonnage quantities of strip and fibre in a wide range of materials. Typical thicknesses vary from 150–700 μm depending on liquid alloy surface tension and process parameters. Here a number of crystalline alloys considered for their soft magnetic properties have been cast in air and an enclosed atmosphere. The surface tensions measured by a modified oscillating droplet technique indicate that small impurity concentrations can markedly affect strip properties. As yet no strong reduction annealing effect on coercivity has been established.

Au–Zn–Si liquid-metal ion source emitting multiple p- and n-type ion species for compositional disordering of GaAs–AlGaAs multiquantum wells

We developed a new type of alloyed liquid‐metal ion source (LMIS) for maskless ion implantation in III–V compound semiconductors. This ion source, consisting of alloys of Au65Zn11Si24 is capable of emitting Zn (p‐type dopant) and Si (n‐type dopant). The lifetime of this ion source was restricted to about 50 h due to a selective evaporation of Zn atoms from the liquid alloy surface. However, the vapor pressure of Zn in the alloy at 410 °C was estimated to be 2.3×10−3 Pa (1.7×10−5 Torr). This value is four orders of magnitude smaller than the elemental Zn. Using this ion source, intermixing of GaAs and AlGaAs layers was selectively performed in an undoped GaAs–AlGaAs multiquantum well structure by alternate implantation with 100‐keV Zn and 80‐keV Si focused ion beams. This disordering technique using focused p‐ and n‐type ion beams offers the possibility of creating a variety of novel structure devices.

Capillary Alloying: An Improved Alloying Method

Alloying of metals to semiconductors is studied by using a liquid alloy contained in a capillary and fed from a large reservoir of alloy. The diffusion constant of germanium in liquid indium is found to be . The alloying method described permits the preparation of uniformly alloyed small contacts to semiconductors. It is demonstrated that extremely flat junctions can be prepared and that the distance of these junctions from the wafer surface can be controlled at as shallow a depth as 0.25 µ. Advantages of this new method include (a) very high degree of purity of the liquid alloy surface previous to alloying, (b) the possibility of investigating conveniently a large number of alloy compositions, and (c) avoiding the handling of extremely small pellets.