Catalytically active nickel {110} surfaces in growth of carbon tubular structures

Abstract

Recent interest in the growth of aligned carbon nanotube films using transition metal catalysts has led to questions concerning the growth mechanism involved. In our experiment carbon tubules grown using Ni catalysts exhibit a preferred orientation relative to the catalytically active surfaces of Ni. The axial directions of the tubular structure are mainly parallel to the ͗110͘ and ͗042͘ directions of Ni. The faceted shape of the Ni particles determines the intrinsic structure of the tubules. A mechanism involving spiral growth is proposed to explain the nucleation and growth of such tubules.

TEM investigation on the growth mechanism of carbon nanotubes synthesized by hot-filament chemical vapor deposition

“…The reaction temperature is about 700 8C. At this temperature the Ni film began to break into small islands driven by the surface tension to lower the total energy and the compressive stress due to the difference the thermal expansion coefficients between the Si and Ni (Merkulov and Lowndes, 2000;Kuang and Wang, 2000). Energy dispersive X-ray analysis (EDS) reveals that these small islands are nanoparticles mainly containing Ni and a small amount of Si, which can provide the nucleation sites for growth of the CNTs.…”

A thermodynamic model for the melting of supported metal nanoparticles

“…The melting of supported nanoparticles is also important in carbon nanotube growth and other catalytic processes [11,12], and for the stability of devices assembled from nanoparticles [13,14]. Thus it is of interest to study the effect of the substrate on the melting point of a supported nanoparticle.…”

Low temperature growth of carbon nanotubes on printing electrodes by MPCVD

“…As the process proceeded, the CNTs were formed and lifted up the metal from the substrate. It has been proposed that the surface melting point of nanoparticles can be as low as 40% of the bulk melting point by the surface curvature effect [14,15]. In addition, Ni nanoparticle could form a eutectic mixture with carbon and/or hydrogen, which can also reduce the melting point.…”