Carbon nanoparticles synthesized by sputtering and gas condensation inside a nanocluster source of fixed dimension

This paper presents the results of the production of carbon nanoparticles by magnetron sputtering inside a gas aggregation tube of fixed dimension, placed vertically in a high vacuum chamber. The nanoparticles are negatively charged, and their morphology was studied according to the positive biasing of a substrate holder. The carbon nanostructures were deposited on formvar grids to be analyzed by transmission electron microscopy. For positive bias voltages larger than 30. V, results showed spherical and randomly dispersed nanoparticles with a mean diameter, which varied from about 10. nm to 20. nm depending on the choice of plasma parameters. By contrast, if the bias voltage was grounded or was lower than or equal to 30. V, only nanoribbon-like structures mixed with compact or fractal groups of nanoparticles were observed on TEM grids. Results are discussed in terms of a 3-step process inside the aggregation tube: nucleation, coalescence and agglomeration of negatively charged nanoparticles.