Screw Dislocation-Driven Growth of Two-Dimensional Nanoplates
Department of Chemistry, University of Wisconsin - Madison , 1101 University Avenue, Madison, Wisconsin 53706, United States. Nano Letters
(Impact Factor: 13.59).
09/2011; 11(10):4449-55. DOI: 10.1021/nl202689m
We report the dislocation-driven growth of two-dimensional (2D) nanoplates. They are another type of dislocation-driven nanostructure and could find application in energy storage, catalysis, and nanoelectronics. We first focus on nanoplates of zinc hydroxy sulfate (3Zn(OH)(2)·ZnSO(4)·0.5H(2)O) synthesized from aqueous solutions. Both powder X-ray and electron diffraction confirm the zinc hydroxy sulfate (ZHS) crystal structure as well as their conversion to zinc oxide (ZnO). Scanning electron, atomic force, and transmission electron microscopy reveal the presence of screw dislocations in the ZHS nanoplates. We further demonstrate the generality of this mechanism through the growth of 2D nanoplates of α-Co(OH)(2), Ni(OH)(2), and gold that can also follow the dislocation-driven growth mechanism. Finally, we propose a unified scheme general to any crystalline material that explains the growth of nanoplates as well as different dislocation-driven nanomaterial morphologies previously observed through consideration of the relative crystal growth step velocities at the dislocation core versus the outer edges of the growth spiral under various supersaturations.
Available from: Sondipon Adhikari
- "Nanoplates such as GS are being found in potential application areas such as in nano-electronic mechanical-systems (NEMS) , nanosensors , nanoactuators , transistor  , solar cells   , biomedical , space elevator lifts in the form of nanoribbons and in nanocomposites. One important technological advancement to the concept of the single or mono nanoplates  is that of the complex-nanoplatesystems . The complex nanoplates can be considered as composite nanostructure. "
[Show abstract] [Hide abstract]
ABSTRACT: This paper reports an analytical study on the buckling of double-nanoplate-system (DNPS) subjected to biaxial compression using nonlocal elasticity theory. The two nanoplates of DNPS are bonded by an elastic medium. Nonlocal plate theory is utilized for deriving the governing equations. An analytical method is used for determining the buckling load of DNPS under biaxial compression. Difference between nonlocal uniaxial and biaxial buckling in DNPS is shown. Both synchronous and asynchronous buckling phenomenon of biaxially compressed DNPS is highlighted. Study shows that the small-scale effects in biaxially compressed DNPS increases with increasing values of nonlocal parameter for the case of synchronous modes of buckling than in the asynchronous modes of buckling. The buckling load decrease with increase of value of nonlocal parameter or scale coefficient. In biaxial compression higher buckling modes are subjected to higher nonlocal effects in DNPS. Further the study shows that the increase of stiffness parameter brings uniaxial and biaxial buckling phenomenon closer while increase of aspect ratio widen uniaxial and biaxial buckling phenomenon.
[Show abstract] [Hide abstract]
ABSTRACT: Copper (Cu) nanowires (NWs) are inexpensive conducting nanomaterials intensively explored for transparent conducting electrodes and other applications. However, the mechanism for solution growth of Cu NWs remains elusive so far. Here we show that the one-dimensional anisotropic growth of Cu NWs and nanotubes (NTs) in solution is driven by axial screw dislocations. All three types of evidence for dislocation-driven growth have been conclusively observed using transmission electron microscopy (TEM) techniques: rigorous two-beam TEM analysis that conclusively characterizes the dislocations in the NWs to be pure screw dislocations along <110> direction, twist contour analysis that confirms the presence of Eshelby twist associated with the dislocation, and the observation of spontaneously formed hollow NTs. The reduction-oxidation (redox) electrochemical reaction forming the Cu NWs presents new chemistry for controlling supersaturation to promote dislocation-driven NW growth. Using this understanding to intentionally manipulate the supersaturation, we have further improved the NW growth by using a continuous flow reactor to yield longer Cu NWs under much milder chemical conditions. The rational synthesis of Cu NWs with control over size and geometry will facilitate their applications.
Available from: nanoscience.engr.wisc.edu
[Show abstract] [Hide abstract]
ABSTRACT: Free-standing two-dimensional nanostrucutures, such as graphene and semiconductor nanomembranes (NMs) featuring their integration with flexible polymer substrates, address applications in which electronic devices need to be stretchable or conformally positioned to nonplanar surfaces. We report a surfactant-directed surface assembly approach to producing large-area NMs at the water-air interface. The NMs were produced by employing the surfactants as templates as well as incorporating them in the crystal structures. By using excess amount of sodium dodecylsulfate (SDS), a tightly packed monolayer of dodecylsulfate (DS) ion was formed and directed the crystallization of submillimeter-sized zinc hydroxy dodecylsulfate (ZHDS) single-crystalline NMs over the entire water surface. This free-standing NM can be readily transferred to an arbitrary substrate and converted to ZnO via heat treatment. A flexible thin-film transistor was also fabricated using the transferred NMs and demonstrated reasonably good n-type transport properties. This approach circumvented the needs of single-crystalline substrates for making large-area NMs from materials that do not possess a laminate structure. It is a low-cost and large-scale synthesis technique and has great potential in developing NMs and flexible devices from various functional materials that are not feasible by conventional selective etching or delamination approaches.
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.