Fullerene peapods: In-situ conductivity study during synthesis

We report in-situ measurement of the conductivity during the synthesis of C-60-filled single-walled carbon nanotubes (SWNTs), so-called fullerene peapods. The synthesis was performed in a sealed quartz tube at 773 K by using the sublimation of C-60 into the hollow space of the SWNTs. The change in the resistance in the SWNT buckypaper was monitored during the C-60-filling process, and the temperature dependence of the resistance was compared to that for empty SWNTs and fullerene peapods. The SWNT networks became more metallic due to the encapsulation of C-60, and a reduced temperature dependence of the resistivity was observed in the peapods, with an overall decrease in the resistivity. The interaction between the SWNT and C-60 molecules, changing the electronic properties of SWNTs, can provide a way to functionalize the SWNTs.