Wetting and energetics in nanoparticle etching of graphene

Molten metallic nanoparticles have recently been used to construct graphene nanostructures with crystallographic edges. The mechanism by which this happens, however, remains unclear. Here, we present a simple model that explains how a droplet can etch graphene. Two factors possibly contribute to this process: a difference between the equilibrium wettability of graphene and the substrate that supports it, or the large surface energy associated with the graphene edge. We calculate the etching velocities due to either of these factors and make testable predictions for evaluating the significance of each in graphene etching. This model is general and can be applied to other materials systems as well. As an example, we show how our model can be used to extend a current theory of droplet motion on binary semiconductor surfaces

Wetting, interfacial interactions and sticking in glass/steel systems

Wetting and sticking of soda-lime glass on two types of stainless steel as well as on platinum and vitreous carbon substrates are studied in a neutral gas atmosphere between 860 and 1200degreesC. Wetting is measured by the "transferred drop" version of the sessile drop technique, enabling fully isothermal spreading kinetics to be monitored. Sticking is investigated by measuring the temperature of glass drop detachment from the substrate during cooling below the vitreous transition temperature. Characterization of substrate and glass surfaces after separation is carried out using surface profilometry, atomic-force microscopy (AFM) and scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) spectroscopy. The character of molten glass wetting on metal (reactive or non-reactive) and the type of interactions ensuring ultimate wetting and adhesion (physical or chemical) are identified and discussed. The factors controlling glass spreading kinetics and those governing glass/steel sticking are also evidenced. (C) 2004 Elsevier B.V. All rights reserved

Diffusion-limited reactive wetting: Spreading of Cu-Sn-Ti alloys on vitreous carbon

When wetting is promoted by interfaces, the rate at which the liquid spreads over the solid substrate is controlled by the rate at which the well-wetted interfacial product can be formed along the liquid/solid/atmospheric triple line. If this reaction involves a reactive alloy addition to the liquid, the rate of spreading can be limited by two phenomena. A simplified analysis of diffusion- limited reactive spreading of Cu-Sn-Ti alloys on vitreous carbon was conducted based on the assumption that the interfacial reaction is strictly localized at the triple line. The addition of 3at.%Ti to Cu-15at.%Sn led to very good wetting on vitreous carbon. This was due to the formation, at the interface, of a continuous layer of TiC

A tight-binding potential for atomistic simulations of carbon interacting with transition metals: Application to the Ni-C system

We present a tight-binding potential for transition metals, carbon, and transition metal carbides, which has been optimized through a systematic fitting procedure. A minimal basis, including the s, p electrons of carbon and the d electrons of the transition metal, is used to obtain a transferable tight-binding model of the carbon-carbon, metal-metal and metal-carbon interactions applicable to binary systems. The Ni-C system is more specifically discussed. The successful validation of the potential for different atomic configurations indicates a good transferability of the model and makes it a good choice for atomistic simulations sampling a large configuration space. This approach appears to be very efficient to describe interactions in systems containing carbon and transition metal elements