Formation of fullerene-like structure by low-energy ion beam doping

Shimoyama, Iwao   ; Baba, Yuji  ; Sekiguchi, Tetsuhiro  ; Uddin, M. N.*; Nagano, Masamitsu*

Carbon alloys formed by B and N dopings is expected for some applications, e.g., catalyst and semiconductor. However, the relationship between doping and material properties is not clear enough because of complicated structures around dopant atoms due to various chemical conditions between ternary system of B, C, and N. We measured polarization dependence of near-edge X-ray absorption fine structure (NEXAFS) to investigate configuration of local structure around dopant atoms in BN co-doped graphite. B and N K-edge NEXAFS spectra showed graphite-like polarization dependence and some * peaks in the spectra showed different magnitude of polarization dependence. This indicates existence of local structures which have distorted planar configuration. We propose a fullerene-like structure for the distorted planar configuration based on comparison of structure stability calculated by a molecular orbital theory with model clusters.