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, wh ere x = 0, 6, 8 and 10 at.%) samples are presented. Changes in the ave rage bond lengths and bond angles are observed as the nitrogen content is varied; however, no qualitative structural differences are seen be tween 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 concentra tion. 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, al though this is not the dominant bonding environment of N. The data ind icate 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 fo rmation of graphitic clusters, and the structure remains disordered ov erall.