AIP Conference Proceedings -- September 30, 1999 -- Volume 486, Issue 1, pp. 196-199

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Cluster-assembled amorphous carbon nano-foam synthesised by high-pulse-rate laser ablation

A. V. Rode,¹ E. G. Gamaly,² R. G. Elliman,¹ A. S. Kheifets,¹ and B. Luther-Davies¹

¹Reserach School of Physical Sciences and Engineering, Australian National University, ACT 0200, Canberra, Australia
²Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, Apartado Postal 55-534, 09340, Mexico D.F., Mexico

We report on a new fractal amorphous carbon nano-foam with a large fraction of tetrahedrally-bonded atoms. The material was produced by high-repetition-rate laser ablation in an argon-atmosphere which resulted in a high collision frequency between carbon atoms and ions in the laser plume and argon atoms in the chamber. This creating the optimal vapor temperature and density for the efficient formation of 4-membered sp³ bonds typical of diamond. The bulk density of various foam samples is in the range (2–10)·10^–3 g/cm^–3, whilst the specific surface area is 300–400 m²/g comparable to that of carbon aerogels. At low temperatures the as-deposited foam exhibits a strong positive electrostatic charge and non-linear current-voltage characteristics with strong hysteresis, indicative its insulating nature. After annealing, the resistivity of the foam measured at low-voltage (±30 V) is (1–3)·10⁹ Ohm·cm at room temperature and (1–10)·10¹³ Ohm·cm at 80 K, with virtually no hysteresis. The DC conductivity of this low-density carbon foam and its temperature dependence appears to be very close to that of RF-sputtered solid amorphous diamond-like carbon films. ©1999 American Institute of Physics.

PACS: 81.05.Ys, 72.80.Ng      Additional Information