Formation of fullerene-like structures by B and N doping in graphite

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

B-C-N hybrid has medium composition between semi-metallic graphite and insulating hexagonal boron nitride, and has been theoretically predicted that semiconducting property is obtained depending on composition and atomic arrangement. Since the structure of the products has not been clarified well, we used near edge X-ray absorption fine structure (NEXAFS) to analyze local structure of B-C-N hybrid. Samples were prepared by ion beam deposition method with borazine gas as a precursor. B and N K-edges NEXAFS spectra were measured for some samples which had different compositions, and showed plural peaks which have different polarization dependences. This result suggests that distorted plane structures were formed at B and N sites. We calculated partial density of states (PDOS) for some model clusters by an ab initio molecular orbital calculation, and proposed that distorted plane structures consist of pentagons and hexagons which is termed as fullerene-like structure.