The filling of carbon nanotubes with magnetoelectric Cr2O3

We report the encapsulation of the antiferromagnetic and magnetoelectric oxide Cr₂O₃ inside both multi - and single-walled carbon nanotubes. This is achieved by a two step post-synthesis filling process which involves the filling of nanotubes with CrO₃ either from aqueous solution or from the molten phase, followed by appropriate annealing sequences. TEM imaging confirms significant filling rates for both multi- and single-walled carbon nanotubes. Analytical transmission electron microscopy implies that after secondary annealing Cr₂O₃ is formed inside the nanotubes.