Improved growth of aligned carbon nanotubes by mechanical activation
- PDF / 1,214,303 Bytes
- 4 Pages / 612 x 792 pts (letter) Page_size
- 37 Downloads / 230 Views
Improved growth of aligned carbon nanotubes by mechanical activation Y. Chena) and L.T. Chadderton Research School of Physical Sciences and Engineering, The Australian National University, Canberra, ACT 0200, Australia (Received 11 January 2004; accepted 13 May 2004)
Straight aligned carbon nanotubes with multiwalled cylindrical structure have been produced by pyrolysis of iron phthalocyanine (FePc) after ball milling treatment. The pre-ball milling treatment prevented the formation of curved nanotubes with bamboo or conelike structures. X-ray diffraction analysis revealed that the milled FePc has an activated and disordered structure, which contributes a lower vaporization temperature determined by thermal gravimetric analysis. The low formation temperature and an increased nanotube growth rate are favorable to the formation of cylindrical structure than bamboo tubes.
Growth of aligned and patterned carbon nanotubes (NTs) is an important step toward the fabrication of nanotube electronic devices in a large scale. Aligned multiwalled NTs have been successfully produced using various types of chemical vapor deposition (CVD) methods.1–5 One example is the formation of large areas of parallel NTs by pyrolysis of iron phthalocyanine (FePc).5,6 However, the aligned nanotubes obtained often have a large diameter of up to several hundred nanometers and complicated structures including bamboo- or conelike structures, which lead to uncontrollable electronic and mechanical properties. Different approaches have been tried to improve structural quality of aligned NTs, i.e., the use of two furnaces allowing better control of the growth temperatures.5 In this work, we demonstrate that a prior ball-milling treatment of iron phthalocyanine (FePc) can significantly enhance the formation of tubular structure of aligned nanotubes. The modern technique of high-energy ball milling has a large range of applications in the processing of carbon nanotubes, including synthesis of nanotubes in both carbon and boron nitride (BN),7,8 opening of closed nanotubes,9 the cutting of long nanotubes into short lengths,10 and in assisting functionalization.11 Iron phthalocyanine was selected because it contains both a carbon source and metal catalysts required for
a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2004.0398 J. Mater. Res., Vol. 19, No. 10, Oct 2004
http://journals.cambridge.org
Downloaded: 16 Mar 2015
aligned nanotube growth. Therefore, predeposition of metal catalysts on a substrate is not needed. In addition, solid FePc powders can be pretreated by high-energy ball milling at room temperature to produce new chemical and thermal properties so that we can control the growth rate, nanotube size and nanostructures. Two grams of FePc were first milled in a rotating ball mill using a stainless steel vessel and four steel balls.7,8 The milling experiment lasted for 100 h in Ar gas at a pressure of 300 kPa, and a disordered, activated nanostructure was created. A long milling time of 100 h was
Data Loading...
