Low energy nitrogen ions are used in this work to manipulate wetting properties of the surface of the array of Cu2O nano-columns, which yields remarkable results. The nano-columnar thin films were grown on a highly conductive silicon surface by a sputter deposition technique. The films were irradiated at two different fluences of 5 × 10(15) and 1 × 10(16) ions per cm(2), respectively. With increasing fluence the shape of column tip changes, columns are bent and porous channels between columns are clogged up. While the surface of the pristine sample is hydrophilic, the irradiated surface turns into hydrophobic but having adhesion properties. We have analysed the structural and chemical properties of the surface in detail to understand the initial and modified wetting properties. Furthermore, the temporal evolutions of different droplet parameters are investigated to realize the interactions between the water droplet, the sample surface and the atmosphere. We envisage that such modified surfaces can be beneficial for transport of a small volume of liquids with minimum loss and spectroscopic studies, where a small amount of water droplet is available for measurements.
Crystalline hydrogen titanate (H2Ti3O7) nanowires were irradiated with N(+) ions of different energies and fluences. Scanning electron microscopy reveals that at relatively lower fluence the nanowires are bent and start to adhere strongly to one another as well as to the silicon substrate. At higher fluence, the nanowires show large-scale welding and form a network of mainly 'X' and 'Y' junctions. Transmission electron microscopy and Raman scattering studies confirm a high degree of amorphization of the nanowire surface after irradiation. We suggest that while ion-irradiation induced defect formation and dangling bonds may lead to chemical bonding between nanowires, the large scale nano-welding and junction network formation can be ascribed to localized surface melting due to heat spike. Our results demonstrate that low energy ion irradiation with suitable choice of fluence may provide an attractive route to the formation and manipulation of large-area nanowire-based devices.
Nanostructured materials are gaining increasing importance due to their unique properties resulting from the high surface to volume ratio and the altered characteristics of the nanoscaled building blocks. The properties of these materials depend strongly on their microstructure and thus can be controlled by inducing transformation on the nanoscale. In this work, a simple low energy ion beam irradiation technique is presented that can be used to effectively weld the hydrogen titanate nanotubes into a large-scale network of nanowires. By varying the ion fluence, we are able to fragment the entire nanowire network into uniformly distributed nanocrystalline particles with an average size of 5 ± 2 nm. Three-dimensional computer simulations of the ion irradiation effects on the nanotubes reproduce most of the experimental findings and thus confirm that the early development of the system is governed by atomic collision processes. Our study demonstrates that the selective use of ion irradiation can transform metal-oxide nanotubes into large-scale welded networks of nanowires and further into nanocrystalline particles through nucleation and growth.
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