In situ transmission electron microscopy of individual carbon nanotetrahedron/ribbon structures in bending

Abstract

When the direction of flattening of a carbon nanotube changes during growth mediated by a metal nanoparticle, a carbon nanotetrahedron is formed in the middle of the carbon nanoribbon. We report the bending properties of the carbon nanotetrahedron/nanoribbon structure using a micromanipulator system in a transmission electron microscope. In many cases, bending occurs at an edge of the carbon nanotetrahedron. No significant change is observed in the tetrahedron's shape during bending, and the bending is reversible and repeatable. Our results show that the carbon nanotetrahedron/nanoribbon structure has good durability against mechanical bending. In our previous paper, we reported that a change in the direction of flattening of a carbon nanotube, grown from an Fe catalyst particle by chemical vapor deposition (CVD), resulted in the formation of a carbon nanotetrahedron in the middle of a carbon nanoribbon. 11 We expect that the carbon nanotetrahedron/nanoribbon structure inherits the excellent properties of CNTs and carbon nanoribbons. Furthermore, it might be possible to obtain additional unique properties owing to the presence of the carbon nanotetrahedra or to find ways of utilizing the structure's characteristics. An example would be to use the structure for three-dimensional wiring, exploiting its shape having two directions of flattening. In order to examine whether our carbon nanotetrahedron/nanoribbon structures can be used for this purpose, we have examined their durability against Joule heating in a transmission electron microscope, and revealed that the nanotetrahedra were as stable as CNTs. 12 When using the carbon nanotetrahedron/nanoribbon structure in flexible devices, it is also important to understand its durability against mechanical strain. In this paper, we focus on the mechanical behavior of the carbon nanotetrahedron/nanoribbon structure under bending. Its structure during bending is observed in situ in a TEM.In our simplified CVD growth of carbon nanotetrahedron/nanoribbon structures, a 20-nm-thick layer of Fe was deposited on a Si (100) substrate, whose surface was roughened using SiC powder to obtain a fresh surface. Then, the sample was sealed in an evacuated silica tube (inner diameter ¼ 6 mm; length % 20 cm) with 0.8 mg of hexadecanoic acid [C 15 H 31 C(¼O)OH] as a carbon source. The sample was heated at 1000 C for 30 min, then cooled to room temperature after the growth. The grown carbon nanostructures were mounted on a Au wire by scratching the Au wire on the substrate on which the carbon nanostructures were grown for in situ TEM observation of bending. The Au wire was mounted on a TEM sample holder equipped with a piezo-driven micromanipulator. An electrochemically sharpened W needle was used as a mobile probe. Charge coupled device (CCD) camera images were recorded at a frame rate of about 2.6 fps with a resolution of 512 Â 512 pixels during in situ observations of bending. For simple TEM observations, the carbon nanotetrahedron/nanoribbon structures were mounted on a carbon microgr...

In situ TEM visualization of superior nanomechanical flexibility of shear-exfoliated phosphorene

“…From the bending and scrolling experiments, we find that the bent or scrolled SPNs did not spontaneously return to its original flake-like morphology. This finding indicate that unique puckered structure of black phosphorus could be responsible for extraordinary mechanical properties of the SPNs, which is different from the previous reports of carbon nanotubes, 35 graphene and boron nitride nanoribbons, 34 where the bending process was spontaneously reversible, with the nanoribbons or nanotubes returning to their pristine morphologies when unloading the applied external force. Interestingly, we did not observe naturally scrolled edges for the suspended SPNs if no external force was introduced, as shown in Fig.…”

In situ fabrication and investigation of nanostructures and nanodevices with a microscope

“…The mechanical strength was found to change significantly and sometimes even totally degenerate due to severe tube buckling. 104,105 Therefore, mechanical and structural aspects are of critical importance for the performance of nanoscale building blocks. For a bulk specimen, the uniaxial tensile loading test is a prime approach to assess its mechanical properties.…”

Atomistic perspective on in situ nanomechanics

“…However, those studies cannot resolve the atomic-level bending deformation and failure mechanisms yet. The in situ TEM method has been recently employed to study the bending of nanostructured materials [133][134][135] . Han's group developed a novel technique of bending using a cracked colloidal thin film for characterizing the atomic-scale bending deformation in semiconductor and metallic nanowires 95,132,[136][137][138] .…”