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We investigated the effect of a rotating anode on the formation of single-walled carbon nanotubes (SWNTs) using the plasma rotating electrode process. With rotation of the anode, the diameter distribution of SWNTs was shifted toward smaller diameters, and the yield of SWNTs increased. In addition, optical emission spectroscopy confirmed the increase of plasma temperature by rotating anode. These results indicate that the diameter distribution of SWNTs and the increase of SWNT yield resulted from the change of discharge characteristics by rotation of the anode. [ABSTRACT FROM AUTHOR]

We investigated plasma rotating electrode process (PREP) as a method for diameter control of single-walled carbon nanotubes (SWNTs) with a Ni–Y catalyst in He ambient. Compared with the diameters of SWNTs produced by the conventional arc discharge (0 rpm), those of SWNTs, which were synthesized by PREP (5000 and 10 000 rpm), were decreased. This result indicated that the centrifugal force by the rotation of anode could control the diameter distributions of SWNTs by controlling kinetic energies of carbon and/or metal species or formation region of SWNTs. [Copyright &y& Elsevier]

Field emission properties of carbon nanotubes (CNTs) deposited by electrophoresis were investigated. Uniform deposition of CNTs on 1×1 cm2 of Ti substrate was observed by scanning electron microscopy (SEM). In addition, in case of CNTs synthesized by arc discharge, purification of CNTs was also obtained due to the higher electrophoretic velocity of carbon nanotubes than those of other carbon species. It indicates that electrophoresis can be used as the purification method of CNTs. As the result of I–V measurement, CNTs synthesized by arc discharge showed the lowest turn-on-field (J=30 nA/cm2) of 1.77 V/μm. On the other hand, CNTs synthesized by vapor phase growth showed a little higher turn-on-field of 2.28 V/μm. Moreover, turn-on-field of acid treated CNTs had the highest value of 2.77 V/μm. These differences might result from the difference in the electrical conductivity as well as the structural quality of CNTs such as wall and caps structures, radius, defect density, and density of CNTs. [Copyright &y& Elsevier]

B–C–N nanotubes were synthesized by plasma rotating electrode process (PREP) and examined by scanning electron microscope (SEM) and X-ray diffraction (XRD). Compared with results at 0 rpm of the anode, the number of B–C–N nanotubes was increased by rotating the anode. In addition, peak intensity ratio of h-(BN)0.26C0.74 to graphite was increased with rotation of the anode and/or the increase of metal concentration. That indicates the yield of B–C–N nanotubes was increased. These results could be explained by an increase of plasma temperature and a swirl in the plasma by rotation of the anode that promote the mixing to aid chemical reactions between evaporated species and atomic nitrogen. [Copyright &y& Elsevier]

A catalyst for single-wall carbon nanotube could be achieved by an agglomeration process of co-sputtered Co–Mo thin film on flat silicon wafers. Through the control of catalyst size and carbon flux, SWNTs and double-wall carbon nanotubes were synthesized. The addition of Mo in the Co catalyst makes an effective nucleation site for SWNT formation and the feeding of CH4 gas in chemical vapor deposition reaction keeps the suitable carbon concentration to grow a single-wall structure. [Copyright &y& Elsevier]