NEUTRON-DIFFRACTION STUDIES OF AMORPHOUS CNX MATERIALS

The results of neutron-diffraction experiments performed on two sample s of amorphous CNx, with nitrogen concentrations of 5 and 30 at. %, pr epared by a combination of filtered cathodic are and Kaufman-type ion source, are presented. Increasing the N content of the samples is seen to cause a decrease of the average bond length and the first coordina tion number. An increase in the average bond angle from 113 degrees to 121 degrees is also observed. The pair-distribution functions indicat e that N incorporation results in some transformation of sp(3) C sites to sp(2) sites, but there is no evidence for N inducing the formation of crystalline graphitic clusters, and the overall structure remains amorphous. A direct subtraction of the two data sets emphasizes the lo ss of sp(3) bonds and the increasing sp(2) character of the higher-N-c ontent sample, and shows the occurrence of a variety of bonding enviro nments for N. More limited information on second neighbor correlations involving N is also revealed.