| Summary: | In this paper we have demonstrated successfully for the first time, a simple but efficient and reliable approach for the growth of multi walled carbon nanotubes (MWCNTs) with high degree of crystallinity, purity and density under a wide range of growth parameters. Multi-walled carbon nanotubes (MWCNTs) were synthesized at 800 - 950 °C by thermal chemical vapor deposition (TCVD) method using a thin nickel film as catalyst and methane gas as carbon source. In this process, two substrates were placed in a long alumina boat inside a double-heater TCVD. One of the substrates was covered with a short upside down alumina boat. The prepared nanotubes were characterized by scanning electron microscopy (SEM) and field emission scanning electron microscopy (FESEM) and it was found that, CNT growth on the covered substrate was improved in terms of quality and density compared to the other uncovered substrate. In addition, the nanotube diameter is reduced more than half. Results also revealed that the temperature gradient played a key factor for growth efficiency and purity of nanotubes. In addition, the diameter of CNT can be influenced by growth temperature too. The catalyst thickness and gas flow rate were found to influence the diameter and density of tubes, whereas the effect of synthesis time was on the CNT length. This growth technique is unique because of its simplicity, high efficiency and its ability to yield CNTs of high purity and density. This finding is supported by Raman spectrometry analysis. © 2012 SPIE.
|
|---|