GRAPHITIZATION OF PYROCARBONS - AN STM STUDY

Scanning tunneling microscopy (STM) has been used to image at atomic r esolution the surface of pyrocarbons deposited at 1680-degrees-C and h eat-treated at temperatures up to 2800-degrees-C. Information is obtai ned on the increase of surface order with HTT. Of special interest are the presence, in HTT 2000 samples, of point defects arranged in a (sq uare-root 7 x square-root 7) R 19. 1-degrees superstructure and attrib uted to an array of interstitial carbon atoms, and the observation of a moire pattern in the HTT 2200 sample, which could be due to the turb ostratic nature of the layer stacking.