Characterization of Carbon Powder Produced by a Microwave-Plasma Torch at Atmospheric Pressure

Carbon powder synthesized by an atmospheric microwave-plasma torch is characterized in terms of the mixture ratio of argon to nitrogen in torch gas. Methane as a source of carbon atoms was directly injected into the microwave-plasma torch. The samples deposited on the inner wall of a discharge tube were analyzed by the X-ray diffraction, field-emission scanning electron microscope, field-emission transmission electron microscope, and Fourier transform infrared (FTIR). The synthesized samples showed thornbush-shaped, fingerprintlike, and onionlike structures. It was identified from FTIR data that the samples contain functional groups of very weak C-N, C=N, and CequivN