| Abstract Scope |
This talk provides a brief review of our work on the formation of new Q-phases of silicon and diamond related materials. These phases are formed after nanosecond laser melting of silicon, carbon and BN layers, and subsequent quenching. By controlling the undercooling, the molten layers are converted directly into Q-phases in the form of layers and self-organized nanostructures. This process should be applicable to all of the materials zinc-blende structures. The basic unit of Q-phases is based upon the diamond tetrahedron. When one, two and three units of diamond tetrahedra are packed randomly, we create higher density of Q3, Q2, and Q1 phases. These phases exhibit outstanding properties, including extraordinary hardness, room-temperature robust ferromagnetism, high-field emission, and high-temperature in b-doped Q-carbon. By controlling the undercooling, we form phase-pure diamond and c-BN structures. Since the nonequilibrium laser melting process involves first-order thermodynamic phase transformation, we obtain phase-pure diamond and c-BN phases. |