Radiation damages and bubble formation of ion implanted furan-resin-derived carbon

Furan-resin-derived carbon generally produces a glass-like carbon (GC) having entangled graphene layers after high temperature heat treatments. However, furan-resin-derived carbon produced well-graphitized thin skin on surfaces after heat-treatment at 3000 degrees C. Ar or Xe ions were implanted into the furan-resin-derived carbon heat-treated at 3000 degrees C at energy of 60-160 keV at a fluence ranging from 1x10(15) to 1x10(17) ions/cm(2). Microstructural changes were examined by Raman spectroscopy. The implanted surfaces of the specimens were changed to an amorphous structure by the ion implantation. Moreover, morphological SEM&TEM observations revealed that clear bubbles with diameter of 10-80 nm were present in the Ar+-implanted specimen at a fluence of 1x10(17) ions/cm(2). However, bubbles did not appear in the Ar+-implanted specimen at a fluence of 1 X 10(16) ions/cm(2). On the other hand, bubbles with diameter of 15-30 nm were present in the Xe+-implanted specimens at a fluence of 1x10(16)ions/cm(2).Since ion implantation is a useful technique for surface modification, we used them to investigate the mechanism of well-graphitized thin skin on surfaces of furan-resin-derived carbon after heat-treatment at 3000 degrees C. The Xe+-implanted specimens were subjected to annealing of re-heat-treatment at 3000 degrees C. After the annealing, the bubbles were lost in the interior of specimens by cross-sectional SEM observations. Moreover, on the implanted surfaces appeared big bubbles, which were not presented on the implanted surface before annealing. The sizes of these big bubbles were about 2-10 gm. Using Raman spectroscopy, we observed that on the surface of the big bubbles the structure was re-well-graphitized. On the surface of non-bubbled areas it was less graphitized. Thus annealing provided a restoration of the structural, but much effective only on the bubble surfaces. (c) 2004 Elsevier B.V. All rights reserved.