Formation of bismuth-core-carbon-shell nanoparticles by bismuth immersion during plasma CVD synthesis of thin diamond films

This paper describes an attempt to synthesize bismuth-doped diamond by plasma CVD. Solid bismuth was inserted into the reaction plasma of CH4 and H2. Examination by TEM showed that most of the bismuth was included as Bi nanoparticles in the carbon nanospheres, which segregated at the grain boundary of the diamond polycrystals. Diffraction peaks corresponding to the carbon allotrope Chaoite were observed at the grain boundaries. The Raman spectra showed very complex features between 100-1600 cm-1, suggesting the existance of molecule-like species.