Growth of c-diamond, n-diamond and i-carbon nanophases in carbon-ion-implanted fused quartz

Authors: Peng J. L.; Bursill L. A.; Jiang B.; Orwa J. O.; Prawer S.

Source: Philosophical Magazine B, Volume 81, Number 12, 1 December 2001 , pp. 2071-2087(17)

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Abstract:

Combined high-resolution transmission electron microscopy, selected-area electron diffraction and parallel electron-energy-loss spectroscopy are used to characterize nanophases of carbon found embedded in fused quartz. These appear after implantation of 1 MeV carbon ions, followed by annealing in argon, oxygen and forming gas for 1 h at 1100°C. For argon, virtually all the carbon diffuses out of the substrate with no observable carbon clusters for all doses studied. After annealing in oxygen, a crystalline CO_x phase is identified at the end of range, following a dose of 5 x 10¹⁷ carbon ions cm^-2. Three nanocrystalline carbon phases, including diamond, appear after annealing in forming gas; these form a layer 170 nm beneath the fused quartz surface for all ion doses. The average size of these clusters and the corresponding phases depend on the ion dose; the smallest clusters of 5-7 nm diameter crystallize as fcc Fd3^-m diamond following a dose of 0.5 x 10¹⁷ carbon ions cm^-2, whereas clusters of 8-13 nm diameter, for a higher dose of 2 x 10¹⁷ carbon ions cm^-2, have a Fm 3^-m modified phase of diamond known as n-diamond. The largest clusters (diameter, 15-40 nm) for a dose of 5 x 10¹⁷ carbon ions cm^-2, have the cubic P 2₁3 (or P4₂32) structure known as i-carbon. These buried layered diamond-related materials may have applications for field emission devices.

Language: English

Document Type: Research article

Publication date: 2001-12-01

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