Sn Nanowires Research Articles

Improving wear performance of dual-scale Al–Sn alloys: The role of Mg addition in enhancing Sn distribution and tribolayer stability

The dual-scale structured Al–Sn based alloys are potential alternative for journal bearings of automotive application due to their excellent tribological and mechanical properties. In this work, the authors attempted to further promote wear properties of dual-scale structured Al–12wt% Sn alloys by Mg addition. It has been found that appropriate Mg addition could increase wet-ability and reduce divorced Sn eutectics, resulting improved distribution of Sn phase, strength and ductility. Moreover, the mechanism for the improvement of the wear properties of Mg-containing Al–Sn alloy was revealed, and could be summarized as follows: (1) The improved transportation and distribution of the Sn nanophases, including nanoparticles and nanowires, towards the worn surface effectively reduced the friction coefficient; (2) enhanced Mg-oxide film and tribolayer formation on the mating surfaces and (3) increased stability of tribolayer owing to better combination of the strength and ductility. But excessive Mg addition led to too high amount of Mg2Sn and Mg17Al12 intermetallic phases, which worsen the wear properties. The dual-scale CG-30 Al–Sn with 1.2wt% Mg addition exhibits the best wear performance under the present experiment conditions.

Preparation of highly pure and crystalline carbon nanotubes and their infiltration by paraffin wax

Carbon nanotubes (CNTs) of ultrahigh purity and high crystallinity, which could be used for the encapsulation of nanoscaled materials, were fabricated by the heat treatment of disordered CNT-encapsulated In–Sn nanowires at temperatures lower than 1800°C in H2 under vacuum conditions (pressure of approximately 1Pa). The results showed that nearly 100% of the encapsulated In–Sn alloy was removed at 1800°C, and as much as 99.99% of it at 1600°C. The prepared CNTs were also filled with paraffin wax. A vacuum-based infiltration–purification process proved effective for fabricating the CNT–paraffin hybrid structures at a high filling yield, which was confirmed by thermograms and TEM observations.

Template-based sputtering method for vertically aligned Tin nanotube arrays: From fabrication to superconductivity

Large-scale Tin (Sn) nanotube arrays have been fabricated using template-based sputtering method. By controlling the growth temperature, two kinds of Sn films with either cross-linked or isolated nanotube arrays can be prepared after removal of anodic alumina oxide film. Morphology-dependent superconducting properties and pinning effect of magnetic flux were observed. The magnetic property of the isolated Sn nanotube arrays is similar to the single-crystal Sn nanowires while cross-linked Sn naotube arrays exhibit a typical magnetic property of hard superconductor. This method could provide a low-cost and convenient approach to the fabrication of large-scale ordered metal nanostructures with desirable function.

Elaboration and high resolution TEM characterization of SnO2 nanowires

Graphical abstractDisplay Omitted Highlights? SnO2 nanowires were synthesized by electrodeposition and oxidation in AAO template. ? The growth mechanism of Sn nanowires is a brick-stacked wirelike growth. ? SEM and TEM studies have shown the uniform structures of these nanowires. ? Tetragonal SnO2 phase has been identified by XRD and confirmed by HRTEM. ? HRTEM image shows polycrystalline nanowire with grains size equal to 5nm. Tin dioxide is a wide-band gap (3.6eV) semiconductor with numerous potential applications in batteries, gas sensors, and dye-sensitized solar cells. In this study nanocrystalline tin oxide nanowires have been synthesized by electrochemical deposition and oxidation in anodic aluminum oxide template. Electrochemical synthesis has been controlled by chronoamperometry and oxidation by X-ray diffraction. Polycrystalline nanowires with 140nm in diameter and 3µm in length have been obtained. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies have highlighted a uniform nanowire structure. High resolution transmission electron microscope (TEM FEI Tecnai G2-20 twin) was employed to characterize the crystalline structure of 5nm diameter tin oxide grains. Tetragonal tin oxide phase has been characterized by X-ray powder diffraction and the interplanar distance of 0.32nm corresponding to the SnO2 crystal obtained by HRTEM has confirmed the structure.

One-Pot Synthesis of Tin-Embedded Carbon/Silica Nanocomposites for Anode Materials in Lithium-Ion Batteries

We report a facile "one-pot" method for the synthesis of Sn-embedded carbon-silica (CS) mesostructured (nanostructured) composites through the selective interaction of resol (carbon precursor), tetraethylorthosilicate (TEOS), and tributylphenyltin (Sn precursor) with an amphiphilic diblock copolymer, poly(ethylene oxide-b-styrene), PEO-b-PS. A unique morphology transition from Sn nanowires to spherical Sn nanoparticles embedded in CS framework has been obtained. Metallic Sn species are homogeneously embedded in a rigid CS framework and are effectively confined within the nanostructures. The resulting composites are used as anode materials for lithium-ion batteries and exhibit high specific capacities (600 mA h g⁻¹ at a current density of 45 mA g⁻¹, and 440 mA h g⁻¹ at a current density of 300 mA g⁻¹) and an excellent cyclability of over 100 cycles with high Coulombic efficiency. Most of all, the novel method developed in this work for synthesizing functional hybrid materials can be extended to the preparation of various functional nanocomposites owing to its versatility and facileness.

Synthesis of branched Sn/carbon nanotube core/shell structures

Branched Sn/carbon nanotube (CNT) core/shell structures were synthesized by employing the catalytic chemical vapor deposition method over SnO2 nanowires for the first time. Detailed analysis showed that the backbones are mainly composed of CNTs, and the branches have a core/shell structure with a Sn nanowire as the core and a CNT as the shell. The thickness of the carbon layer capped on the Sn nanowires is about 20nm. The Sn nanowires have lengths of about several micrometers and diameters of about 40nm. A formation mechanism of the branched nanostructures is suggested.

Selective synthesis and superconductivity of In–Sn intermetallic nanowires sheathed in carbon nanotubes

We demonstrate a simple and reproducible technique to synthesize crystalline and superconducting In–Sn intermetallic nanowires sheathed in carbon nanotubes (CNTs). The method is based on the catalytic reaction of C2H2 over a mixture of both SnO2 and In2O3 particles. Importantly, tetragonal β-In3Sn and hexagonal γ-InSn4 nanowires with diameters of less than 100 nm are selectively synthesized at different SnO2 to In2O3 weight ratios. CNTs may serve as cylindrical nanocontainers for continuous growth of liquid-phased In1−xSnx nanowires during growth process as well as for their solidification into In–Sn intermetallic nanowires during the cooling process. Microscopic and spectroscopic analyses clearly reveal evidence of a core–shell structure of the CNT-sheathed In–Sn intermetallic nanowires. Magnetization measurements show that the superconducting In–Sn nanowires have a critical magnetic field higher than the value of their bulk intermetallic compounds. Our method can be adopted to the nanofabrication of analogous binary and ternary alloys.

Transformation of Sn nanowires to oxide nanotubes by a localized corrosion process

Amorphous SnO nanotubes were synthesized from Sn nanowires (NWs) electrodeposited into anodic aluminum oxide templates by a localized corrosion process in an aqueous solution composed of chromic, phosphoric, and hydrochloric acids. Initially, phosphoric acid dissolves the template, while chromic acid generates a SnO passivation layer on the NW surface. As a volume expansion occurs during the surface oxidation, some cracks occur at the top surface of the passivation layer. In addition, Cl ions from the hydrochloric acid assist the cracking. Subsequently, Sn atoms in the core of the NW dissolve into the acidic solution while the oxide layer at the shell remains to form nanotubes. Finally, Sn NWs with a length of 10μm and diameter of 30nm are completely transformed to amorphous SnO nanotubes with a wall thickness of 10nm. After heat-treatment, the amorphous nanotubes were crystallized into polycrystalline SnO phase with a rough surface morphology.

Stable high areal capacity lithium-ion battery anodes based on three-dimensional Ni–Sn nanowire networks

Nanowire arrays present an excellent candidate for high performance lithium-ion battery electrodes. However, agglomeration in long nanowire arrays impedes nanowire-based electrodes from delivering high areal capacity, by degrading the nanoscale wires to micro-sized bundles and reducing the mechanical stability. In this study, we develop a simple way to fabricate three-dimensional (3D) nickel–tin (Ni–Sn) nanowire networks by using 3D porous anodic alumina templates synthesized from low-cost impure aluminum foils. By eliminating agglomeration, stable high areal capacity anodes are demonstrated with 3D self-supporting Ni–Sn nanowire network structures. With a nanowire length of 40μm, the 3D Ni–Sn nanowire networks can deliver an areal capacity as high as 4.3mAhcm−2 with a cycle life longer than 50 cycles. The 3D Ni–Sn nanowire networks also exhibit an excellent rate capability with 72% of the capacity retained when the test rate increases from C/5 to 6C.

Structure and Optical Properties of SnS Nanowire Arrays Prepared with Two-Step Method

Abstract. Single crystalline SnS nanowire arrays have been synthesized by sulfurating the Sn nanowire arrays which were prepared with the electrochemical deposition. The obtained SnS nanowire arrays are charactered with the XRD, SEM, TEM and the UV/Visible/NIR spectrophotometer. And the results indicate that the nanowires with an average diameter of 50 nm and a length of several tens micrometers, which same with the as prepared Sn nanowires. There are two absorption peaks indicate with the direct and indirect bandgaps about the orthorhombic SnS nanowire arrays.

A Mobile Sn Nanowire Inside a β‐Ga2O3 Tube: A Practical Nanoscale Electrically/Thermally Driven Switch

Nanoelectromechanical system switches are seen as key devices for fast switching in communication networks since they can be switched between transmitting and receiving states with an electrostatic command. Herein, the fabrication of practical, nanoscale electrically/thermally driven switches is reported based on a mobile Sn nanowire inside a β-Ga2 O3 tube. The melting point of Sn inside the Ga2 O3 tube is found to be as low as 58 °C-far below the value of bulk Sn (231.89 °C)-and its crystal phase (β-Sn) remains unchanged even at temperatures as low as -170 °C. Thus a miniaturization of the unique wide-temperature-range thermometer based on the linear thermal expansion of liquid Sn fillings in the Ga2 O3 tube is realized. In addition, the electrical properties of the Sn-nanowire-filled β-Ga2 O3 tubes are carefully determined: importantly, the resistance demonstrates a sudden drop (rise) when two Sn nanowires contact (separate), due to the thermally driven motion of the liquid Sn fillings inside the tube. Thus this structure can be switched between its on and off states by controlling the motion, merging or splitting, of the Sn nanowires inside the tube, either electrically, by applying a current, or thermally, at a predetermined temperature.

Enhancing Ni–Sn nanowire lithium-ion anode performance by tailoring active/inactive material interfaces

Nanowire arrays have attracted great attention due to their great potential to improve the performance of Li-ion batteries. In this work, we studied anode performance of lithium-ion batteries using Ni–Sn nanowire arrays. A versatile method through a porous anodic alumina (PAA) template-assisted electrochemical deposition process was developed to directly synthesize Ni–Sn nanowire arrays on copper current collectors. This method presents significant advantage that the as-prepared Ni–Sn nanowire arrays can be directly used as anode electrode without any binder or conductive materials. However, the formation of a continuous Ni–Sn film at the base of the nanowires result in quick loss of electrical contact between the active material and the current collector because of the large strain mismatch at the large continuous active/inactive material (A/I) interface. By growing short Cu nanoscrews as a buffer layer before Ni–Sn nanowire growth, the formation of Ni–Sn film was inhibited and the A/I interface was scaled down to nanoscale islands. The strain mismatch is thus significantly reduced, which results in enhanced structural stability and battery performance. The effect of the composition and the length of Ni–Sn nanowire arrays on the electrochemical performance of lithium ion batteries are also systematically studied.

Size-dependent lattice parameters of microstructure-controlled Sn nanowires

Abstract

Electrodeposition of rhenium–tin nanowires

Rhenium (Re) is a refractory metal which exhibits an extraordinary combination of properties. Thus, nanowires and other nanostructures of Re-alloys may possess unique properties resulting from both Re chemistry and the nanometer scale, and become attractive for a variety of applications, such as in catalysis, photovoltaic cells, and microelectronics. Rhenium–tin coatings, consisting of nanowires with a core/shell structure, were electrodeposited on copper substrates under galvanostatic or potentiostatic conditions. The effects of bath composition and operating conditions were investigated, and the chemistry and structure of the coatings were studied by a variety of analytical tools. A Re-content as high as 77at.% or a Faradaic efficiency as high as 46% were attained. Ranges of Sn-to-Re in the plating bath, applied current density and applied potential, within which the nanowires could be formed, were determined. A mechanism was suggested, according to which Sn nanowires were first grown on top of Sn micro-particles, and then the Sn nanowires reduced the perrhenate chemically, thus forming a core made of crystalline Sn-rich phase, and a shell made of amorphous Re-rich phase. The absence of mutual solubility of Re and Sn may be the driving force for this phase separation.

Conformal Coating of Thin Polymer Electrolyte Layer on Nanostructured Electrode Materials for Three-Dimensional Battery Applications

Various three-dimensional (3D) battery architectures have been proposed to address effective power delivery in micro/nanoscale devices and for increasing the stored energy per electrode footprint area. One step toward obtaining 3D configurations in batteries is the formation of core-shell nanowires that combines electrode and electrolyte materials. One of the major challenges however in creating such architectures has been the coating of conformal thin nanolayers of polymer electrolytes around nanostructured electrodes. Here we show conformal coatings of 25-30 nm poly(methyl methacralate) electrolyte layers around individual Ni-Sn nanowires used as anodes for Li ion battery. This configuration shows high discharge capacity and excellent capacity retention even at high rates over extended cycling, allowing for scalable increase in areal capacity with electrode thickness. Our results demonstrate conformal nanoscale anode-electrolyte architectures for an efficient Li ion battery system.

Stress-induced Sn Nanowires from Si–Sn Nanocomposite Coatings

The growth of stress-induced tin (Sn) whiskers has been considered responsible for the failure of many electronic devices and many approaches have been developed to mitigate their growth. In this report, however, we describe a simple approach based on the same mechanism to promote the growth of Sn nanowires. The thermal expansion induced stress was utilized as the driving force to initiate the growth of Sn nanowires from Si–Sn phase-separated nanocomposite coatings. The nanostructure of the Si–Sn matrix was the key to controlling the shape and diameter of Sn nanowires. This approach provides additional flexibility for making desirable metallic nanowires with controlled dimensions.

Porous anodic alumina membranes formed by anodization of AA1050 alloy as templates for fabrication of metallic nanowire arrays

The through-hole porous anodic aluminum oxide (AAO) membranes were fabricated by a two-step anodization of the aluminum alloy (AA1050) in 0.3M oxalic acid at 45V and 20°C followed by removal of Al and pore opening/widening procedures. The effect of duration of the second anodizing step on the porous oxide layer thickness and the influence of the pore opening time on structural features of as-prepared membranes were studied in detail. The prepared membranes with a thickness of about 60μm were used as templates for fabrication of dense arrays of Ag, Au, and Sn nanowires with various aspect ratios by a DC electrochemical deposition process. The successful synthesis of metallic nanowires by simple DC electrodeposition of metals inside the pores of AAO templates fabricated from the AA1050 alloy was reported for the first time. The fabrication costs of nanowire arrays can be reduced by about 500 times when AAO templates, prepared from the AA1050 alloy, are used instead of those usually formed from expensive high purity Al.

Origins of size-dependent lattice dilatation in tetragonal Sn nanowires: Surface stress and growth stress

Through experiments and theoretical analyses, we demonstrate that Sn nanowires can shrink or expand when the radius decreases from 120 to 1.2 nm. Single crystalline nanowires manifest [100]-longitudinal lattice dilatations that originate from the strong anisotropy of the surface stress. Compressive growth stress, which is generated in the radial direction during the growth of nanowires within templates, leads to greater elongation due to the Poisson effect. The surface stress-induced lattice strains are intrinsic, whereas the growth stress-induced lattice strains can be released. For polycrystalline nanowires, lattice contractions occur because the anisotropy of surface stresses is effectively reduced.

Evaluation of Sn Nanowire Encapsulated Carbon Nanotube for a Li-Ion Battery Anode by DFT Calculations

Hybrid nanomaterial of Sn nanowire encapsulated carbon nanotube (SnNW@CNT) for a 1-D nanostructure Li-ion battery anode is evaluated by using DFT electronic structure and molecular dynamics calculations. We reveal that ultrathin SnNW is thermodynamically stable within CNT and it is prone to have a disorder structure. In addition, SnNW@CNT can enhance Li uptake as compared with pure CNT due to the energetically favorable Li-SnNW alloying process. More importantly, we reveal that an optimized SnNW@CNT has a void space thickness of ∼5 A between the nanostructures, indicating that the radial void spaces are only enough for accommodating the fully lithiated SnNW within CNT(n,0) when n < 27. The results suggest that such nanowire encapsulated nanotube materials have to be made ultrathin in order to become an effective hybrid nanomaterial for a Li-ion battery anode.

Conductance Response of Tin Nanowires to the External Axial Pressure Load

Five different optimized Sn nanowires embedded in single-walled carbon nanotubes (SWCNTs) are obtained by means of molecular dynamics (MD) simulation. Growth of Sn nanowires follows a helical or parallel pattern in confined space. Optimized Sn nanowires subject to compression are investigated. Results reveal that a four-strand-parallel nanowire can resist the highest pressure load among these five kinds of nanowires studied. The growth pattern of a nanowire determines its conductance response to the pressure load. Interestingly, conductance of double-helical and four-strand-parallel nanowires (which have an even number of atomic chains) increases with pressure load, while the conductance of three-strand-helical and five-strand-helical nanowires (which have an odd number of atomic chains) is found to decrease with pressure load. On the basis of the conductance response of the nanowire to the external pressure load, nanosensors can be fabricated to detect the stress and strain of nanostructured materials.