Synthesis of diamond-like carbon structure by Na-ion implantation in graphite and polyacetylene

A study has been made of the structures of diamond-like carbon by analyzing Raman spectra of ion-implanted carbon. Substrates used were glass-like carbon and high-density polyacetylene [HD-(CH)(x)]. Sodium ion implantation was performed with doses of 1 x 10(15) x 10(17) ions cm(-2) at an energy of 150 keV. Raman spectra of glass-like carbon have two peaks at 1585 and 1360 cm(-1), which correspond to graphite (G-peak) and disordered graphite (D-peak), respectively. Ion implantation causes these two peaks to broaden, and finally, the Raman spectra show an asymmetric broad peak, showing the formation of diamond-like carbon. An intact polyacetylene has two Raman peaks around 1500 and 1150 cm(-1), which are due to the C=C stretching mode (nu 1) and a mixed mode (nu 3) of the CH bending and C-C single bond stretching vibration, respectively. Ion implantation in polyacetylene causes the appearance of two new peaks at 1360 and 1585 cm(-1), which seem to correspond to D-peak and G-peak, respectively. High-dose ion implantation causes the Raman spectrum to have an asymmetric broad peak that is almost the same as that observed from the ion-implanted glass-like carbon. From the variation of Raman spectra, it is concluded that the Raman spectrum with an asymmetric broad peak is composed of four components: G-peak, nu 1 mode, D-peak and nu 3 mode. The relationship between wear resistance and Raman spectra will be discussed. (C) 1998 Elsevier Science S.A.