Ultrahigh Tensile Strength Nanowires with a Ni/Ni-Au Multilayer Nanocrystalline Structure

Deformation of Copper Nanowire under Coupled Tension–Torsion Loading

Metallic nanowires (NWs) are essential building blocks for flexible electronics, and experience different deformation modes due to external mechanical loading. Using atomistic simulations, this work investigated the deformation behavior of copper nanowire under coupled tension–torsion loading. A transition in both yielding pattern and dislocation pattern were observed with varying torsion/tension strain ratios. Specifically, increasing the torsion/tension strain ratio (with larger torsional strain) triggered the nucleation of different partial dislocations in the slip system. At low torsion/tension strain ratios, plastic deformation of the nanowire was dominated by stacking faults with trailing partial dislocations pinned at the surface, shifting to two partial dislocations with stacking faults as the strain ratio increases. More interestingly, the NW under tension-dominated loading exhibited a stacking fault structure after yielding, whereas torsion-dominated loading resulted in a three-dimensional dislocation network within the structure. This work thus suggests that the deformation behavior of the NW varies depending on the coupled mechanical loading, which could be beneficial for various engineering applications.

Multi-Segmented Nanowires: A High Tech Bright Future

In the last couple of decades, there has been a lot of progress in the synthesis methods of nano-structural materials, but still the field has a large number of puzzles to solve. Metal nanowires (NWs) and their alloys represent a sub category of the 1-D nano-materials and there is a large effort to study the microstructural, physical and chemical properties to use them for further industrial applications. Due to technical limitations of single component NWs, the hetero-structured materials gained attention recently. Among them, multi-segmented NWs are more diverse in applications, consisting of two or more segments that can perform multiple function at a time, which confer their unique properties. Recent advancement in characterization techniques has opened up new opportunities for understanding the physical properties of multi-segmented structures of 1-D nanomaterials. Since the multi-segmented NWs needs a reliable response from an external filed, numerous studies have been done on the synthesis of multi-segmented NWs to precisely control the physical properties of multi-segmented NWs. This paper highlights the electrochemical synthesis and physical properties of multi-segmented NWs, with a focus on the mechanical and magnetic properties by explaining the shape, microstructure, and composition of NWs.

Metallic Fe-Au Barcode Nanowires as a Simultaneous T Cell Capturing and Cytokine Sensing Platform for Immunoassay at the Single-Cell Level

Barcode nanowires (BNWs) composed of multiple layered segments of different materials are attractive to bioengineering field due to their characteristics that allow the adjustment of physicochemical properties and conjugation with two or more types of biomolecules to facilitate multiple tasks. Here, we report a metallic Fe (iron)-Au (gold) BNW-based platform for capturing CD8 T cells and the interferon-γ (γ) they secrete, both of which play key roles in controlling infectious diseases such as tuberculosis, at the single-cell level. We also describe an efficient approach for conjugating distinct antibodies, which recognize different epitopes to appropriate materials. The platform achieved detection even with 4.45-35.6 μg mL^-1 of BNWs. The T cell capture efficiency was close to 100% and the detection limit for interferon-γ was 460 pg mL^-1. This work presents a potential guideline for the design of single-cell immunoassay platforms for eliminating diagnostic errors by unambiguously identifying disease-relevant immune mediators.

Deformation of Single Crystals, Polycrystalline Materials, and Thin Films: A Review

With the rapid development of nano-preparation processes, nanocrystalline materials have been widely developed in the fields of mechanics, electricity, optics, and thermal physics. Compared to the case of coarse-grained or amorphous materials, plastic deformation in nanomaterials is limited by the reduction in feature size, so that they generally have high strength, but the toughness is relatively high. The "reciprocal relationship" between the strength and toughness of nanomaterials limits the large-scale application and development of nanomaterials. Therefore, the maintenance of high toughness while improving the strength of nanomaterials is an urgent problem to be solved. So far, although the relevant mechanism affecting the deformation of nanocrystalline materials has made a big breakthrough, it is still not very clear. Therefore, this paper introduces the basic deformation type, mechanism, and model of single crystals, polycrystalline materials, and thin films, and aims to provide literature support for future research.

High strength metallic wood from nanostructured nickel inverse opal materials

This paper describes a nickel-based cellular material, which has the strength of titanium and the density of water. The material’s strength arises from size-dependent strengthening of load-bearing nickel struts whose diameter is as small as 17 nm and whose 8 GPa yield strength exceeds that of bulk nickel by up to 4X. The mechanical properties of this material can be controlled by varying the nanometer-scale geometry, with strength varying over the range 90–880 MPa, modulus varying over the range 14–116 GPa, and density varying over the range 880–14500 kg/m³. We refer to this material as a “metallic wood,” because it has the high mechanical strength and chemical stability of metal, as well as a density close to that of natural materials such as wood.

Nucleation-Controlled Plasticity of Metallic Nanowires and Nanoparticles

Nanowires and nanoparticles are envisioned as important elements of future technology and devices, owing to their unique mechanical properties. Metallic nanowires and nanoparticles demonstrate outstanding size-dependent strength since their deformation is dislocation nucleation-controlled. In this context, the recent experimental and computational studies of nucleation-controlled plasticity are reviewed. The underlying microstructural mechanisms that govern the strength of nanowires and the origin of their stochastic nature are also discussed. Nanoparticles, in which the stress state under compression is nonuniform, exhibit a shape-dependent strength. Perspectives on improved methods to study nucleation-controlled plasticity are discussed, as well the insights gained for microstructural-based design of mechanical properties at the nanoscale.

Influence of dislocations, twins, and stacking faults on the fracture behavior of nanocrystalline Ni nanowire under constant bending load: a molecular dynamics study

In this paper, constant load bending tests were performed on a nanocrystalline Ni nanowire specimen at different deformation temperatures using molecular dynamics simulation to investigate deformation behavior and mechanisms responsible for fracture. The nature of the fracture occurred in this nanowire specimen is found to transit from brittle to ductile as the temperature rises from 500 to 800 K. Also, with an increase in temperature, the fracture strain is increased indicating more plastic deformation prior to fracture. In the case of 500 K and 600 K deformation temperatures, fracture occurred along the shear band due to slip-twin interaction. On the other hand, at comparatively higher deformation temperatures, such as 700 K and 800 K, twinning and detwinning mechanisms are responsible for accommodating large plastic strain before fracture thus imparting plasticity in the specimen. It has also been found that formation and collapse of the stacking fault tetrahedron causes fracture of nanocrystalline Ni nanowire at 800 K.

Flaw-Containing Alumina Hollow Nanostructures Have Ultrahigh Fracture Strength To Be Incorporated into High-Efficiency GaN Light-Emitting Diodes

In the present study, we found that α-alumina hollow nanoshell structure can exhibit an ultrahigh fracture strength even though it contains a significant number of nanopores. By systematically performing in situ mechanical testing and finite element simulations, we could measure that the fracture strength of an α-alumina hollow nanoshell structure is about four times higher than that of the conventional bulk size α-alumina. The high fracture strength of the α-alumina hollow nanoshell structure can be explained in terms of conventional fracture mechanics, in that the position and size of the nanopores are the most critical factors determining the fracture strength, even at the nanoscales. More importantly, by deriving a fundamental understanding, we would be able to provide guidelines for the design of reliable ceramic nanostructures for advanced GaN light-emitting diodes (LEDs). To that end, we demonstrated how our ultrastrong α-alumina hollow nanoshell structures could be successfully incorporated into GaN LEDs, thereby greatly improving the luminous efficiency and output power of the LEDs by 2.2 times higher than that of conventional GaN LEDs.

Synthesis of Co nanotubes by nanoporous template-assisted electrodeposition via the incorporation of vanadyl ions

We report a facile fabrication concept for nanotubes (NTs) based upon template-assisted electrodeposition, which is widely applied for metallic nanowire (NW) synthesis. Co NTs have been synthesized into nanoporous anodized aluminum oxide (AAO) templates via electrodeposition by simply adding a small amount of chemicals including vanadyl ions (VO²⁺).