| 초록 |
An electric arc discharge technique is a potential candidate for the large-scale production of single-walled carbon nanotubes (SWCNTs) with excellent crystalline quality among many synthesis routes. However, SWCNTs soot thereby produced does not contain only SWCNTs, but also a significant amount of carbonaceous nanoparticles and metallic catalyst particles mainly encapsulated with carbonaceous nanoparticles. Depending on the production method, the purity of as-produced SWCNTs ranges from 10 to 70%, which is simply assessed by different specific metrics. There are several qualitative and quantitative techniques routinely used to characterize the properties of SWCNT-bearing samples, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis-NIR spectroscopy, thermogravimetric analysis (TGA), Raman spectroscopy, etc. Extensive information can be extracted from the portion of interest in a sample by using these tools. In this study, we evaluated the purity of SWCNTs in the soot and oxidized samples, using TGA. The carbon phases can be moderately differentiated in TGA derivative curves if knowing thermal stability of each constituent phase. We prepared the soot samples whose compositions were changed upon oxidizing at different temperatures of 275~425 ˚C for 20 h, then analyzed by TGA, SEM, and TEM. Deconvoluted derivative curves showed systematic variations with the temperatures, and each of them could be assigned to a corresponding constituent phase based on microscopic observations. Their compositions were calculated by measuring the areas under the deconvoluted curves. |
