Nanoscale Encapsulation of Molybdenum Carbide in Carbon Clusters

Formation of rounded forms of carbon offers a unique opportunity to study the properties of materials constrained in nanoscale environments. Encapsulation of molybdenum carbide in polyhedral carbon nanoparticles is found to stabilize the face-centered-cubic form at the expense of the commonly encountered hexagonal-close-packed form. This reveals an important role for the carbon nanoclusters and/or nanotubes of catalyzing the synthesis of materials with novel structural forms in their nanoscale environment. The encapsulated carbide is superconducting with a Tc ∼ 10.5 K.