New carbide crystallites, which have a solid-solution phase with diamond structure, were formed from amorphous carbon film containing a transition metal such as Fe, Co, Mo or Ti by vacuum heating at 500-800 degrees C. The lattice constants for each solid-solution phase have been determined from electron diffraction patterns and high-resolution transmission electron microscope images. The formation of carbon polymorphs has been summarized as being dependent on the heat treatment temperature. (c) 2004 Elsevier B.V. All rights reserved.