High-yield Synthesis of Multiwalled Carbon Nanotube by Mechanothermal Method.

S A Manafi,M R Rahimipour,E Salahi,M H Amin,A Kazemzadeh

doi:10.1007/s11671-008-9240-3

S A Manafi, M R Rahimipour + Show 3 more

Open Access

https://doi.org/10.1007/s11671-008-9240-3

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Abstract

This study reports on the mechanothermal synthesis of multiwalled carbon nanotube (MWCNTs) from elemental graphite powder. Initially, high ultra-active graphite powder can be obtained by mechanical milling under argon atmosphere. Finally, the mechanical activation product is heat-treated at 1350°C for 2–4 h under argon gas flow. After heat-treatment, active graphite powders were successfully changed into MWCNTs with high purity. The XRD analyses showed that in the duration 150 h of milling, all the raw materials were changed to the desired materials. From the broadening of the diffraction lines in the XRD patterns, it was concluded that the graphite crystallites were nanosized, and raising the milling duration resulted in the fineness of the particles and the increase of the strain. The structure and morphology of MWCNTs were investigated using scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The yield of MWCNTs was estimated through SEM and TEM observations of the as-prepared samples was to be about 90%. Indeed, mechanothermal method is of interest for fundamental understanding and improvement of commercial synthesis of carbon nanotubes (CNTs). As a matter of fact, the method of mechanothermal guarantees the production of MWCNTs suitable for different applications.

Highlights

Since the time of discovery by Iijima [1], there has been much interest in the synthesis and physical properties of carbon nanotubes (CNTs) due to their important applications
Various methods have been developed for the synthesis of carbon nanotubes, including metalcatalyzed chemical vapor deposition (CVD) [6,7,8], arc evaporation [9], laser ablation of carbon [10], catalytic decomposition [11], HiPCO process [12] or pulsed laser vaporization (PLV) [13]
There are growing experimental evidences, showing that the formation of both multiwalled and single-walled nanotubes involves a solid-phase transformation in the gas-phase synthesis processes [14,15,16]. It implies that a direct synthesis of CNTs by a transformation of solid carbons under mild conditions is possible; if accessible, it would be quite beneficial for a largescale synthesis due to the intrinsic high-feeding- density characteristic of the solid-phase reaction process

Summary

Introduction

Since the time of discovery by Iijima [1], there has been much interest in the synthesis and physical properties of carbon nanotubes (CNTs) due to their important applications. We study mechanothermal method for synthesizing MWCNTs that consists of mechanical milling (for obtaining amorphous carbon nanostructure using ultra-high purity graphite powders) and thermal annealing processes (for transforming into nanotubes via carbon nanostructure and structural crystallization). The final gas pressure in the vial was kept at 0.1 MPa. After full amorphization, the highly chemically active carbon powders were annealed at different temperatures to investigate the formation of MWCNTs. The crystal phase was determined with powder X-ray diffraction.

Results

Conclusion