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The graphene double-walled carbon nanotube (DWCNT) hybrid films were prepared by vacuum filtration and screen printing. Their electron field emission properties have been studied systematically. The electron emission properties of the hybrid films are much better than those of pure DWCNT films and pure graphene films. Comparing with the screen printed films, the vacuum filtered films have many advantages, such as lower turn-on field, higher emission current density, better uniformity, better long term stability, and stronger adhesive strength with conductive substrates. The optimized hybrid films with 20% weight ratio of graphene, which were fabricated by vacuum filtration, show the best electron emission performances with a low turn-on field of 0.50V μm-1 (at 1 μAcm-2) and a high field enhancement factor β of 27000. [ABSTRACT FROM AUTHOR]

In addition to Ni, Co, and Fe, the authors show that a copper (Cu) chromium (Cr) alloy can be a good catalyst for controlled growth of carbon nanotubes (CNTs). A thermal chemical vapor deposition was used at 600 °C to deposit the CNTs, and a dual-target magnetron sputtering system was used to control the ratio of the Cu/Cr alloy. The material properties of the CNTs, such as concentration, diameter, and density, are directly affected by the ratio of Cu/Cr alloy, which subsequently affect the field-emission properties. Their results showed that Cr can be used to effectively control the catalytic effects of the Cu catalysts, where the quality of the CNTs could vary while the density could be controlled from 4×107 to 5×1010 tubes/cm2. The field-emission current density of the CNT film increases with Cu/Cr ratio from 1/6.4 to 4.6/1 and decreases when the Cu/Cr ratio is more than 4.8/1 in the alloy film. When the Cu/Cr ratio is at 4.6/1, the average current density peaks at 5129 μA/cm2 at the applied field of 3.53 V/μm, showing an optimized field-emission property. [ABSTRACT FROM AUTHOR]

Growth of carbon nanotube (CNT) films with good field emission properties on glass is very important for low cost field emission display (FED) applications. In addition to Ni, Co and Fe, Cu can be a good catalyst for CNT growth on glass, but due to diffusion into SiO2 it is difficult to control the CNTs density and uniformity. In this paper, four metal barrier layers (W, Ni, Cr, Ti) were deposited by dc magnetron sputtering on glass to reduce the Cu diffusion. As-grown CNT films showed various morphologies with the use of different barrier metals. CNTs with uniform distribution and better crystallinity can be synthesized only on Ti/Cu and W/Cu. Voltage current measurements indicate that better field emission properties of CNT films can be obtained on titanium and tungsten barriered Cu, while chromium and nickel are not suitable barrier candidates for copper in CNT-FED applications because of the reduced emission performance. [ABSTRACT FROM AUTHOR]

Freestanding two-dimensional (2D) few-layer graphene was formed through laser exfoliation of highly ordered pyrolytic graphite, using a pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) laser. Graphene sheets of several nanometers in thickness and micrometers in size were obtained. The laser exfoliation process was investigated at different laser fluences and distances between target and substrate. Three different phases, amorphous carbon, few-layer graphene sheets, and thin graphite films, were obtained as the laser fluence increased. This study reveals an existing route of forming freestanding 2D nanostructures through laser exfoliation. [ABSTRACT FROM AUTHOR]

Abstract: Low energy ion beam assisted deposition (IBAD) was employed to prepare Ag films on Mo/Si (100) substrate. It was found that Ag films deposited by sputtering method without ion beam bombardment were preferred (111) orientation. When the depositing film was simultaneously bombardment by Ar+ beam perpendicular to the film surface at ion/atom arrival ratio of 0.18, the prepared films exhibited weak (111) and (200) mixed orientations. When the direction of Ar+ beam was off-normal direction of the film surface, Ag films showed highly preferred (111) orientation. Monte Carlo method was used to calculate the sputtering yields of Ar+ ions at various incident and azimuth angles. The effects of channeling and surface free energy on the crystallographic orientation of Ag films were discussed. [Copyright &y& Elsevier]