Liquid Metal Phase Research Articles

Phase diagram of the one-dimensional t-J model with long-range dipolar interactions

We study systematically the effect of long-range dipolar interactions on the ground-state phase diagram of the one-dimensional model by means of the density matrix renormalization group. While the basic phases described by the Luttinger parameter , namely, the repulsive Luttinger liquid (metallic phase, ), attractive Luttinger liquid (superconducting phase, ), and the phase separation , are similar to those of the conventional model, the presence of the long-range dipolar interactions leads to significant differences. i) At high-density regime, the phase boundaries of these three phases are even pushed to the large-J region; ii) at low-density regime, these phase boundaries shift toward the small-J region and, most importantly, iii) the spin-gap region spreads across the boundary of , suggesting an exotic metallic phase with spin-gap, which is absent in the conventional model. The result indicates that the long-range dipolar interactions have a significant influence on the ground-state properties of the one-dimensional model. Its implication on the pseudogap phenomenon of the hole-doped cuprates is briefly discussed.

Novel Method for Synthesis of High Nickel Cobalt Aluminum Hydroxide By Engineered Two Step Co-Precipitation Method

Novel Method for Synthesis of High Nickel Cobalt Aluminum Hydroxide by Engineered Two Step Co-precipitation Method Kitae Kim, Minah Cha, Jangsuk Hyun, Tae-Hwan Yu, Wooyoung Yang, Jeong-Ju Cho Battery Materials R&D Team, Samsung Fine Chemicals, Suwon, Gyeonggi-do 443-803, S.Korea NCA is a promising cathode material for high energy lithium ion battery in electric vehicles and hybrid electric vehicles because of high power. It overcomes imperfections such as cycle life, rate capability, and low thermal stability with higher specific capacity compared to Ni-rich cathode materials.1-3 For NCA preparation, there are various methods, but specifically, solid-state reaction of metal oxide and liquid phase synthesis of metal salts using continuous stirred tank reactor have been used. 4-6 However, the former method is not suitable for commercialization due to homogeneous mixture problems and economic issue. Furthermore, although using the overflow continuous reactor is a good method to control particle growth and to get spherical particles,7 it has broad particle distribution. Also, it is hard to synthesize the NCA hydroxide with desired target size and high tap density which would affect volumetric capacity because the addition of Al precursors during the precipitation of transition metal may have an effect on the chemical condition for nucleation and growth of formation of NCA(OH)2 precursors, especially pH and concentration of solution during synthesis.7 In this study, the coprecipitation method using engineered reactor was used in order to overcome the problems of non-uniform dispersal of Al in transition metal and broad size distribution of products. The method for making NCA hydroxide with desired size and tap density was demonstrated as shown in fig 1. NCA hydroxide, which is NC hydroxide with Al affixed on the surface, synthesized by this method has high tap density (over 2.0g/cc). The control of supersaturation during nucleation and crystal growth of Al on the NC hydroxide allows control of Al formation with a few hundred nanometers. This method also allows control for various sizes homogeneously. Through the calcination process with atmosphere control, the Al was well diffused and distributed to the core of the final product, LNCAO2 cathode material. The NCA cathode material has good cycle characteristics because Al, which acts as a ‘pillar’ in the interslab space, can suppress the crystallographic phase and decrease the irreversible capacity4. And it has been investigated by atomic scale probe. The revolutionary method described here is also being used to incorporate other various metal ion sources into transition metal ions to improve electrochemical performance and safety characteristics of high nickel containing cathode materials. Furthermore, this method is useful for triple layer and core-shell cathode material application.

Sulfur solubility of liquid and solid Fe–Cr alloys: A thermodynamic analysis

Abstract Gibbs energy modeling for sulfur solving liquid and solid iron–chromium phases with body- and face-centered cubic structure has been carried out using a substitutional approach. Experimental data available from the literature on sulfur potentials in the temperature range 1 525 to 1 755 °C for the liquid metallic phase and 1 000 to 1 300 °C for the solid alloys have been taken into consideration. Recent thermodynamic evaluations of the Fe–S and Cr–S binary subsystems served as basis for the presented work. The obtained models allow a satisfactory reproduction of the majority of the sulfur potential data as well as the prediction of an isothermal partial section at 1 300 °C. Consistent embedding of the optimized Gibbs energies within a recent thermodynamic modeling of the complete Cr–Fe–S system is achieved.

Thermodynamic modeling of the V–Cr–Si system

In the present work, an assessment of the V–Cr–Si system was done. Mainly based on previously ternary experimental data on the isothermal section at 1200°C and on the liquid–solid equilibria, a thermodynamic modeling of the ternary system was performed within the CALPHAD approach using the Thermo-Calc and the Pandat software packages and taking into account data from existing assessment of binary sub-systems. Four intermediate phases were considered as stoichiometric compounds (Cr,V)x(Si)y with substitution of Cr and V at Si ratio constant: (Cr,V)Si, (Cr,V)5Si3, (Cr,V)11Si8 and (Cr,V)6Si5. Two others phases (Cr,V)Si2 and (Cr,V)3Si presenting a slight domain of homogeneity, were described as (Cr,Si,V)1(Cr,Si)2 and (Cr,Si,V)3(Cr,Si,V)1 respectively. The metallic liquid phase and the terminal solid solutions of chromium and vanadium were described by the disordered solutions model as (Cr,Si,V)1(Va)3. The silicon admitting any solubility, its description was limited to (Si). The resulting thermodynamic optimization led to a good agreement with experimental data.

Numerical simulation of multiphase flow in a Vanyukov furnace

The main technologies adopted in the copper and lead reduction industries include the Vanyukov, QSL, SKS, Kivcet, Ausmelt, and ISA furnaces (Hongjiu, 2001; Kojo, Jokilaakso, and Hanniala, 2000). From a fundamental theoretical viewpoint, all of these technologies can be classified as reduction bath smelting furnaces, which are the major research focus in nonferrous metallurgy. However, some of the important physical phenomena and chemical processes inside the furnace remain unknown because of the harsh reaction environments. Fortunately, numerical simulation methods, particularly computational fluid dynamics (CFD), provide an efficient way to study their internal processes. With the development of computer software, many good CFD platforms have been released, such as Fluent and CFX. CFD has become an indispensable tool for the design and optimization of complex chemical reactors. Typical applications included the blast furnace (BF) and aluminum reduction cell. In the copper industry, some papers have been published on numerical studies of the flow pattern. The representative work in this area was carried out by Valencia and co-workers at the Institute for Innovation in Mining and Metallurgy, University of Chile ((Vaencia et al., 2004, 2006; Fuentes et al., 2002). They conducted numerical and experimental studies of the fluid dynamics in a Teniente-type copper converter. A three-dimensional simulation of the three-phase system was carried out using the volume of fluid (VOF) and the standard k e turbulence models implemented in a commercial solver. Their numerical model included the white metal and slag liquid phases, and gas phase through air injection from 50 submerged tuyeres, and experimental observations were carried out in a 1:5-scale water container. The results of these investigations enabled the operation conditions to be optimized. Real (2007) also studied the flow characterization of Peirce-Smith copper converters. Although good results were obtained from the slice model, unfortunately it could not provide the entire flow field distribution of the furnace. Liow and Gray (1990) experimentally studied the formation of standing waves in a water model of a PeirceSmith converter. The results showed that it was possible to obtain regions in the bath depth and tuyere angle/tuyere submergence plots where no standing waves were found and spitting was minimal. Kulkarni and Joshi (2005) presented a comprehensive review of bubble formation and bubble rise velocity in gas-liquid systems. In China, Professor Chi Mei and his group at Central South University (Li, Mei, and Zhang, 2001; Rao, 2010; Li, Chi, and Zhang, 2001; Chen, 2002; Mei et al., 2003) have focused mainly on the reaction kinetics, flow field, and industrial experiments on the copper flash smelting furnace. Numerical simulation of multiphase flow in a Vanyukov furnace

Structural Features of Electrodeposited Metals as a Result of Ultra-Rapid Solidification of a Highly Supercooled Liquid Metal Phase

With a view to validating the existence of the phenomenon of phase formation via a liquid state stage in metals being electrodeposited, experiments were carried out to reveal electrodeposited metal's structural features typical of metals produced by solidification at ultra-high rates under high supercooling, and to establish consistent changes in metal structural characteristics with increasing degree of supercooling in electrodeposition. Following experimental facts in favour of the existence of the phenomenon in point were found: (1) occurrence of spherulites and pentagonal quasicrystals in electrodeposit layers adjoining the cathode, the occurrence being typical of metals produced by ultra-rapid solidification of a highly supercooled liquid metal phase; (2) emergence of the electrodeposited metals solely in a spherulitic form when transition of spherulitic growth to drusy growth with increasing deposit thickness was prevented; and (3) regular change in characteristics of point, linear and planar defects in the crystalline lattice with increasing degree of supercooling in electrodeposition of metals.

Formation of metal being electrodeposited solely in spherulitic form

The aim of the work was the experimental verification of validity of the phenomenon of phase formation through a stage of liquid state in metals being electrodeposited. The idea of the work is based on a known fact that at super-quick solidification of highly undercooled liquid metallic phase the spherulites appear. For the proof of existence of intermediate liquid phase of metal being electrodeposited it was planned to obtain the deposits in spherulitic form. The conditions for the formation of metal being electrodeposited in spherulitic form are discussed and realized. Practical realization of the idea mentioned above was accomplished by combined nickel and chromium alloying of iron being electrodeposited at high current density. As a result of the model experiment the samples of electrodeposited alloyed iron, consisting solely of spherulites, were obtained. The formation of metal being electrodeposited solely in shperulitic form, typical for the metal solidified from liquid state with very high rate in conditions of significant undercooling, proves validity of the phenomenon of phase formation of metals being electrodeposited through a stage of liquid state.

Enhancement of metal bioleaching from sewage sludge by cotton stalk

It was found that the distribution of heavy metals in liquid and solid phases at the end of bioleaching of sewage sludge could be described by adsorption isotherm model. Cotton stalk could be used to improve heavy metal leaching efficiency in bioleaching of sewage sludge. Amended with 5 g/L cotton stalk in late bioleaching, leaching efficiency increased from 56.75, 56.42, and 62.28 to 73.18, 81.34, and 82.39% for copper, lead, and chromium, respectively, with 6% pulp density. Relationship between heavy metals in liquid phase and that adsorbed onto cotton stalk could be described by Freundlich equation. Adsorption onto cotton stalk lowered heavy metal concentration in liquid phase. Consequently, more heavy metals were released from sewage sludge. The increased section of heavy metals released from sludge was mainly attributed to mobile fractions. Content of heavy metals in stable fractions was left unchanged. Mobility of residual heavy metals in sludge after bioleaching with treatment was also lowered greatly.

Interface reactions between liquid iron and alumina–carbon refractory filter materials

The possibility of a carbothermic reaction between alumina and carbon is discussed based on thermodynamic calculations. A thermodynamic assessment of the Fe–Al2O3–Al corner of the Al–Fe–O system was done, and an interaction parameter of the metallic liquid phase was derived to model the solution of aluminium and oxygen in the ternary system. The derived dataset was used to calculate two experimental setups: (1) Fe–Al2O3–12.9 mass%C at 1550°C under argon atmosphere as found in the literature and (2) the possible interface reaction between Fe–Al2O3–30 mass%C at 1650°C. Interface reactions between Al2O3–30 mass%C and Al-killed steel 42CrMo4 at 1650°C were studied experimentally using a steel melt-casting simulator. Large particles of exogenous alumina were found on a thin layer of alumina on top of the refractory material. The formation of an in situ-formed alumina layer can be explained thermodynamically by the partial dissolution of alumina and carbon in the iron melt at the interface and the reprecipitation of alumina at the filter surface.

Separation of Uranium and Lanthanides in a Fused Salt – Liquid Gallium Based Alloy System

Molten salts and metals can be used as working media in pyrochemical reprocessing of spent nuclear fuels (SNF), particularly for separating lanthanides (fission products) and actinides (fission materials). Radiation stability of metals and inorganic salts and absence of neutron moderators allow reprocessing a high burn-up SNF of fast neutron reactors after a relatively short cooling time. Metals of the IIIA group of the periodic table and their alloys are the promising systems for separating SNF components. Low melting points of some of these metals (29.77 °C for Ga, 156.78 °C for In and 15.3 °C for the Ga-In eutectic) allow working in a wide temperature range.The efficiency of separation of SNF’s components in a ‘molten salt – liquid metal’ system can be estimated from the values of separation factor Θ: ΘMe1/Me2 = (c1 · x2)/(c2 · x1),where c1, c2, x1, and x2are the mole fraction concentrations of the separated metals in the fused salt and liquid metal alloy phases, respectively.In the present work the separation factors, Θ, of Ln/U couples were determined from the results of activity coefficients measurements. In chloride melts uranium and lanthanides form ions containing the metals in the oxidation state +3. Therefore the following equation was employed to calculate Θ:lg(ΘMe1/Me2) = n·F·(E* 2 – E* 1)/(2.303RT) + lg(γ1) – lg(γ2),where E* denotes the formal standard electrode potentials of the metals in the salt phase and γ activity coefficients of the same metals in the liquid alloy phase, and the number of exchanged electrons, n, equals to 3. The salt phase was based on the ternary low melting LiCl-KCl-CsCl eutectic (m.p. 263 oC) and the formal electrode potentials of uranium, neodymium and praseodymium in this melt were determined experimentally.Temperature dependencies of activity coefficients of f-elements were calculated using the experimental data on activity (a) and solubility (X) of Pr, Nd and U in liquid Ga, In and Ga-In eutectic alloy. The relation between a, γ and X is expressed by the following equation:lg(a) = lg(γ) + lg(X)The effect of temperature on activity coefficients of Pr, Nd and U in alloys with Ga, In and Ga-In eutectic is shown in Fig. 1. The calculated separation factors, for example, at 723 K of Pr/U couple were 1.6·105 in Ga, 1916 in In, and 7.54·106 in Ga-In eutectic. For Nd/U couple the following values at 723 K were obtained, 1.49·106 for Ga, 1567 for In, and 2.46·106for Ga-In eutectic. The obtained data show that separation of lanthanides and actinides using gallium-indium alloys is possible. The highest separation factors of all studied here Ln/U couples are reached in gallium-containing liquid metal phases and by their magnitude they are virtually identical for Ga and Ga-In alloys. The reason for such behaviour is that at least one of the f-elements (uranium or lanthanide) predominantly interacts with gallium, whilst indium in the eutectic alloy acts as an indifferent additive. As the temperature decreases the efficiency of Ln/An separation is increasing, as expected.From the obtained results it can be concluded that under the equilibrium conditions in the studied ‘liquid metal – molten salt’ system lanthanides should concentrate in the salt phase and actinides (in our case U) should concentrate in the liquid metal. A separate series of experiments run on determination of separation of uranium and lanthanides using Ga-In alloys and LiCl-KCl-CsCl eutectic based melts confirmed this distribution of the elements between the phases.

Influence of experimental setup on amine degradation

Chemical stability of amines under CO2 capture conditions is a well known problem both for process operability and related to economy and environmental issues. Many degradation studies have been conducted under different conditions and in different apparatuses. In this work the chemical stability of a set of amines and their degradation products using 3 different setups have been studied. A new degradation compound for 2-ethanolamine (MEA), N-(2-hydroxyethyl)-2-[(2-hydroxyethyl)amino]-acetamide (HEHEAA) was quantified resulting in a total of 21 degradation compounds for MEA. Liquid phase metal and gas phase oxygen concentrations, temperature and volatility of degradation products (intermediates) all influence degradation and differences in results from the various apparatuses are observed. Conditions favouring formation of primary degradation compounds are difficult to identify and explain, but generally low metal and oxygen concentrations and temperature reduce their formation. For some of the secondary degradation compounds volatility of intermediates was an issue and higher formation rates were seen in the closed setup which preserved more of these products in the solvent compared to the open setup with gas throughput. Amines believed to form volatile degradation compounds showed lower chemical stability in the open setup compared to the closed setup. A new mechanism for the important degradation product N-(2-hydroxyethyl)-glycine (HEGly) is suggested.

Formation of spherulites and pentagonal quasicrystals in metals being electrodeposited

The aim of the work was experimental verification of validity of the phenomenon of phase formation through a stage of liquid state in metals being electrodeposited. The idea of the work was based on the known fact, that at minor undercooling of melt solidification of metal usually occurs in dendritic form, and at significant undercooling of melt dendritic form transfers to spherulite one. At that spherulites, as a rule, are being formed on the interface between metal and a melting-pot. Besides, superfast solidification of greatly undercooled melt causes formation of quasicrystals with pentagonal symmetry. Therefore, if metals being electrodeposited really pass through a stage of undercooled liquid state and rapidly solidify at the deposition temperature, than spherulite forms of crystallization and pentagonal quasicrystals should be detected in their layers adjacent to the cathode. As the result of experimental investigations accomplished by the method of scanning electron microscopy formation of spherulites and pentagonal quasicrystals in the adjacent to the cathode layers of metals (copper, lead and cobalt) being electrodeposited was discovered. It is shown, that presence of spherulites and pentagonal quasicrystals in electrodeposited metals is the result of superfast solidification of undercooled liquid metallic phase being formed during electrochemical deposition of metals. Formation of spherulites and pentagonal quasicrystals in the adjacent to the cathode layers of metals being electrodeposited proves the validity of the phenomenon of phase formation through a stage of liquid state in metals being electrodeposited.

Preparation and Characterization of Carbon-Encapsulated Iron Nanoparticles and Its Application for Core-Shell Type of Catalyst

IntroductionSpherical iron oxide and carbon-encapsulated iron nanoparticles have been prepared by ultrasonic irradiation followed by annealing at various temperatures. As the annealing temperature of the as-prepared α-Fe2O3 nanoparticles was increased, the sample transformed into γ-Fe2O3, Fe3O4, and Fe nanoparticles via the reduction process without requiring any additional reducing agents such as H2 gas, thus creating a carbon shell surrounding the nanoparticles. By controlling the experimental conditions, Fe nanoparticles of various sizes can be formed with diameters in the range 100 - 800 nm; these nanoparticles are tightly encapsulated by 20 nm thick carbon shells. Because of their high saturation magnetization 212 emu·g-1, the carbon-encapsulated Fe nanoparticles can be used for magnetic resonance imaging (MRI) with a dramatically enhanced efficiency compared to commercially available T2contrast agents. Also, it can be used to catalysts system in liquid phase hydrogenation of biomass derived levulinic acid (LA) to γ-valerolactone (GVL) because of the excellent catalytic activity of Fe/C core-shell type as precious/noble metals in liquid phase using water as a solvent.ExperimentalTo perform the facile synthesis of 300 nm α-Fe2O3 nanoparticles, the sono-chemistry method was used, inducing ultrasonic decomposition of raw materials under ambient conditions. Iron (III) acetylacetonate, Fe(acac)3, in octyl ether was sonicated to generate localized hot spots within the acoustic cavitation of collapsing bubbles during ultrasonic irradiation (reaction time is 10 min and the temperature reaches approximately 257 °C). As the annealing temperature of the as-prepared α-Fe2O3 nanoparticles was increased, the sample transformed into various forms: α-Fe2O3 → γ-Fe2O3 → Fe3O4 → Fe. It should be noted that the reduction phenomenon occurred without any additional reducing agents such as H2gas. During the ultrasonic irradiation process, the carbon species generated from the octyl ether would then be embedded in the as-prepared α-Fe2O3 nanoparticles acting as a reducing agent when the annealing temperature increased. The LA hydrogenation was carried out in a 100 ml batch type reactor. Typically, 5.0 g of LA in 45 ml of DI water were added into the reactor, in which 0.2 g of Fe/C was charged. After tighten of reactor, the initial hydrogen pressure was maintained to 5 bar. The reaction was carried out at 170 oC for 3h using 1000 of RPM speed. After cooling of reactor, the product mixture and catalyst were separated by simple filtration. Qualitative and quantitative analysis of products were done by Gas chromatography equipped with Cyclo-Sil B column and FID detector. For recycle study, the recovered catalyst was washed with ethanol and dried it at 120 oC for overnight and used for the next run.Result and DiscussionWe confirmed the chemical composition of the as-prepared α-Fe2O3 using energy-dispersive X-ray analysis (EDS). Results from EDS spectra of as-prepared α-Fe2O3 nanoparticles showed that the sample contained Fe, O, and 52.6 wt % C. Our experimental evidence leds us to believe that the embedded carbon species play an important role as reducing agent in the phase transformation of iron oxide. Embedded carbon species have been studied and developed for their use as reducing agents for rare-earth materials, such as heat treatment of Eu3+-containing materials under a reducing atmosphere (carbon or CO gas). When the annealing temperature increased, the as-prepared α-Fe2O3 nanoparticles were rapidly transformed into γ-Fe2O3 and Fe3O4 via the reduction process; their carbon contents were decreased to 36.5 wt % and 21.6 wt %, respectively. We found that these species could be directly converted into a carbon shell on the surface of the Fe nanoparticles when the annealing temperature was 700 °C. We confirmed the phase transformation from Fe3O4to Fe by XRD as the annealing temperatures increased (Figure 1a). Examination of the sample by FE-SEM and TEM indicates that the carbon shell growth produces Fe nanoparticles encapsulated in a carbon shell (Figure 1b and c). HR-TEM (Figure 1d) image shows that most of the Fe nanoparticles were encapsulated by carbon shell with a diameter of 20 nm.After successful characterization of core-shell Fe/C material, we investigated its hydrogenation activity for LA hydrogenation to GVL in a liquid phase using water as a green solvent. The hydrogenation was carried out in a batch type reactor at 170 oC of reaction temperature and using 5 bar of H2 pressure. The core-shell type of Fe/C catalysts work excellently for this reaction and gave 99.6% of GVL selectivity at 99.5% conversion of LA within 3 h of reaction time, and it could also allow its reusability for 5 times without any significant deactivation in catalytic activity.

Formation of chromium hydride in chromium being electrodeposited alloyed with hydrogen

The aim of the work was experimental verification of validity of the recently discovered phenomenon of phase formation through a stage of liquid state in metals being electrodeposited. The idea of the work was based on the known fact, that during crystallization of liquid phase of a transitional metal (e.g. chromium) alloyed in significant concentration with non-metal of minor atomic radius (e.g. hydrogen) intermediate phases with simple crystal lattices (e.g. hydrides) appear. Therefore, if in electrodeposited chromium alloyed with hydrogen the chromium hydride will be detected, this result will indicate validity of the phenomenon of phase formation through a stage of liquid state in metals being electrodeposited. To find the variants of chromium alloying with hydrogen during its electrodeposition the method for estimation of the degree of hydrogen saturation of metals being electrodeposited was developed. Electrodeposition of chromium was accomplished in such conditions where the volume of hydrogen being formed on the cathode was 62700 times higher than the volume of chromium being formed, which indicated alloying of chromium during its electrodeposition with hydrogen in significant concentration. On the basis of the accomplished experiments the formation of chromium hydride during electrodeposition of chromium alloyed with hydrogen was found. The conclusion, that existence of intermediate phases in electrodeposited metals is a result of crystallization of liquid metallic phase being formed during electrochemical deposition of metals, was made. The obtained result proves the validity of the phenomenon of phase formation through a stage of liquid state in metals being electrodeposited.

Phase transition into the metallic state in hypothetical (without molecules) dense atomic hydrogen

A simple physical model of the metal-dielectric (vapor-liquid) phase transition in hypothetical (without molecules) atomic hydrogen is proposed. The reason for such a transition is the quantum collective cohesive energy occurring due to quantum electron-electron exchange similar to the cohesive energy in the liquid-metal phase of alkali metals. It is found that the critical parameters of the transition are Pc ∼ 41000 atm, ρc ∼ 0.1 g/cm3, and Tc ∼ 9750 K.

Soft-matter composites with electrically tunable elastic rigidity

We use a phase-changing metal alloy to reversibly tune the elastic rigidity of an elastomer composite. The elastomer is embedded with a sheet of low-melting-point Field’s metal and an electric Joule heater composed of a serpentine channel of liquid-phase gallium–indium–tin (Galinstan®) alloy. At room temperature, the embedded Field’s metal is solid and the composite remains elastically rigid. Joule heating causes the Field’s metal to melt and allows the surrounding elastomer to freely stretch and bend. Using a tensile testing machine, we measure that the effective elastic modulus of the composite reversibly changes by four orders of magnitude when powered on and off. This dramatic change in rigidity is accurately predicted with a model for an elastic composite. Reversible rigidity control is also accomplished by replacing the Field’s metal with shape memory polymer. In addition to demonstrating electrically tunable rigidity with an elastomer, we also introduce a new technique to rapidly produce soft-matter electronics and multifunctional materials in several minutes with laser-patterned adhesive film and masked deposition of liquid-phase metal alloy.

Synthesis of solid solutions in double metallic systems by the iodine-transport method

The paper is devoted to investigating the formation of solid solutions of metals from elements by the iodine-transport method. The possibility for the synthesis of a continuous series of solutions of Cu-Ni, as well as solutions of aluminum and silicon in copper, without the formation of liquid metallic phases is shown.

Determination of a Density Functional Tight Binding Model with an Extended Basis Set and Three-Body Repulsion for Carbon Under Extreme Pressures and Temperatures

We report here on development of a density functional tight binding (DFTB) simulation approach for carbon under extreme pressures and temperatures that includes an expanded basis set and an environmentally dependent repulsive energy. We find that including d-orbital interactions in the DFTB Hamiltonian improves determination of the electronic states at high pressure–temperature conditions, compared to standard DFTB implementations that utilize s- and p-orbitals only for carbon. We then determine a three-body repulsive energy through fitting to diamond, BC8, and simple cubic cold compression curve data, as well pressures from metallic liquid configurations from density functional theory (DFT) simulations. Our new model (DFTB-p3b) yields approximately 2 orders of magnitude increase in computational efficiency over standard DFT while retaining its accuracy for condensed phases of carbon under a wide range of conditions, including the metallic liquid phase at conditions up to 2000 GPa and 30 000 K. Our result...

Theoretical Investigation of Atomic Transport Properties of 4d Transition Metals in Liquid Phase

Present article deals with atomic transport properties like self-diffusion coefficient (D) and viscosity coefficient (η) of 4d transition metals in liquid state. To describe structural information we have used different reference systems like Percus - Yevick Hard Sphere (PYHS), One Component Plasma (OCP) and Charge Hard Sphere (CHS) systems alongwith our newly constructed parameter free model potential. To see the effect of different correction functions on atomic transport properties, we have used different local field correction functions like Hartree (H), Vashishta-Singwi (VS), Hubbard-Sham (HS), Sarkar et al (S), Ichimaru-Utsumi (IU), Taylor (T) and Farid et al (F). From the present results we conclude that our newly constructed model potential successfully calculated atomic transport properties of 4d transition metals in liquid phase.

Influence of cross-sectional geometry on the sensitivity and hysteresis of liquid-phase electronic pressure sensors

Cross-sectional geometry influences the pressure-controlled conductivity of liquid-phase metal channels embedded in an elastomer film. These soft microfluidic films may function as hyperelastic electric wiring or sensors that register the intensity of surface pressure. As pressure is applied to the elastomer, the cross-section of the embedded channel deforms, and the electrical resistance of the channel increases. In an effort to improve sensitivity and reduce sensor nonlinearity and hysteresis, we compare the electrical response of 0.25 mm2 channels with different cross-sectional geometries. We demonstrate that channels with a triangular or concave cross-section exhibit the least nonlinearity and hysteresis over pressures ranging from 0 to 70 kPa. These experimental results are in reasonable agreement with predictions made by theoretical calculations that we derive from elasticity and Ohm's Law.