ARC-DISCHARGE METHODOLOGY: SYNTHESIS AND CHARACTERIZATION OF CARBON NANOTUBES
Oudjertli Salah
Abstract: Carbon nanotubes have a property combination that is difficult to ignore. A Young's modulus near 1 TPa, electrical behaviour that flips between metallic and semiconducting depending on how the sheet is rolled, thermal conductivity along the axis that matches diamond all packed into a cylinder a few nanometres wide. That combination is why they have stayed near the top of the research agenda in nanomaterials for thirty years, and why getting the synthesis right actually matters. We produced multi-walled carbon nanotubes by electric arc discharge. The reason for choosing this route over CVD or laser ablation is simple: no metal catalyst is needed, which removes the main contamination problem before it starts. Two graphite electrodes at 99.999% purity were mounted face-to-face inside a stainless-steel chamber filled with helium at sub-atmospheric pressure. A DC arc was struck between them, and the carbon sublimated from the anode recondensed on the cathode as a soot containing multi-walled nanotubes. Current, voltage, gap width, and helium pressure were all adjusted run by run until the discharge was stable and the cathodic deposit was consistently rich in nanotube material. The powder was then looked at three ways. XRD on a Rigaku Ultima IV with Cu-Kα radiation (λ = 0.154056 nm) gave the crystallographic picture: the (002) reflection sitting at 2θ ≈ 25.9°, an interlayer spacing of 0.343 nm, and a mean crystallite size of 10.10 nm from the Debye–Scherrer equation. These numbers are exactly what you expect from well-graphitized multi-walled nanotube walls. SEM on an FEI Quanta 250 showed the morphology at higher resolution bifurcated and branched structures, outer diameters between 25 and 120 nm, agglomerated into the tangled mat that arc-discharge MWCNTs typically form. EDX found no metallic impurities. Optical microscopy on a NIKON ECLIPSE LV150N polarizing microscope then gave the mesoscale view: how the aggregates are sized and distributed across the powder, and how homogeneous the material looks at the scale relevant to processing. The three datasets fit together and tell a consistent story about what was made structural and compositional information that feeds directly into any subsequent work using these CNTs in nanoelectronics, polymer composites, or protective coatings.
Keywords: CNTs, Electric Arc- Discharge, XRD, SEM, Optical Microscope
DOI: 10.24874/PES08.02B.021
Recieved: Revised: Accepted:
UDC:
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