Neutron and x-ray diffraction studies of a-C:N:H

The results of neutron and x-ray diffraction experiments performed on a range of nitrogen-doped amorphous hydrogenated carbon (a-C:N-x:H, where x = 0, 6, 8 and 10 at.%) samples are presented. Changes in the average bond lengths and bond angles are observed as the nitrogen content is varied; however, no qualitative structural differences are seen between the samples. Both CH and NH correlations are seen directly, and N-H bonds are shown to be favoured over C-H at the highest N concentration. Also for the sample with the highest N content, the data provide evidence for the presence of a small quantity of C=N triple bonds, although this is not the dominant bonding environment of N. The data indicate that N incorporation may result in some transformation of sp(3) C sites to sp(2) sites, but there is no evidence for N inducing the formation of graphitic clusters, and the structure remains disordered overall.