Rapid reversible electromigration of intercalated K ions within individual MoO₃ nanobundle

Rapid and reversible electromigration of intercalated K ions within an individual layered single crystalline K_xMoO₃ nanobundle is observed. When an electric current was applied to a K_xMoO ₃ nanobundle, the K ions migrated readily and rapidly in the flowing direction of electrons within the nanobundle and accumulated near an electrode. Upon reversal of the applied current, the accumulated K ions near one electrode were driven back and gathered near the opposite electrode. This observation is attributed to the unique structure of K_xMoO₃ where K ions occupy O vacancies in the nanobundle and the location of K ions is exactly the channel of high current density within the nanobundle. The duration required to induce significant accumulation of K ions and relaxation time of accumulated ions were significantly shorter than the value reported in other interstitial systems. The reversible ion movement was repeated for hundred times and remarkably there were no obvious sign of structural damage in the nanobundle.