Correlation between atomic rearrangement in defective fullerenes and migration behavior of encaged metal ions

Abstract

Migration behavior of ${\mathrm{Gd}}^{3+}$ and ${\mathrm{Ca}}^{2+}$ ions inside ${\mathrm{C}}_{82}$ fullerene cages with irradiation-induced atomic defects is observed using in situ high-resolution electron microscopy. The encapsulated ${\mathrm{Gd}}^{3+}$ ion can easily leave the fullerene cage through the defect, whereas the ${\mathrm{Ca}}^{2+}$ ion remains inside the defective cage. Density functional theory calculations prove that this atomic behavior closely correlates with the rearrangement of carbon atoms in defective fullerene cages. The ${\mathrm{Gd}}^{3+}$ ion disturbs the self-restoration of the defective cage and assists its polymerization, but such effects are not found for the ${\mathrm{Ca}}^{2+}$ ion.