Diamond nanocrystals formed by direct implantation of fused silica with carbon
We report synthesis of diamond nanocrystals directly from carbon atoms embedded into fused silica by ion implantation followed by thermal annealing. The production of the diamond nanocrystals and other carbon phases is investigated as a function of ion dose, annealing time, and annealing environment. We observe that the diamond nanocrystals are formed only when the samples are annealed in forming gas (4% H in Ar). Transmission electron microscopy studies show that the nanocrystals range in size from 5 to 40 nm, depending on dose, and are embedded at a depth of only 140 nm below the implanted surface, whereas the original implantation depth was 1450 nm. The bonding in these nanocrystals depends strongly on cluster size, with the smaller clusters predominantly aggregating into cubic diamond structure. The larger clusters, on the other hand, consist of other forms of carbon such as i-carbon and n-diamond and tend to be more defective. This leads to a model for the formation of these clusters which is based on the size dependent stability of the hydrogen-terminated diamond phase compared to other forms of carbon. Additional studies using visible and ultraviolet Raman Spectroscopy, optical absorption, and electron energy loss spectroscopy reveal that most samples contain a mixture of sp{sup 2} and sp{sup 3} hybridized carbon phases.
- Research Organization:
- Oak Ridge National Laboratory
- Sponsoring Organization:
- (US)
- DOE Contract Number:
- AC05-00OR22725
- OSTI ID:
- 40277803
- Journal Information:
- Journal of Applied Physics, Vol. 90, Issue 6; Other Information: DOI: 10.1063/1.1388857; Othernumber: JAPIAU000090000006003007000001; 042117JAP; PBD: 15 Sep 2001; ISSN 0021-8979
- Publisher:
- The American Physical Society
- Country of Publication:
- United States
- Language:
- English
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