Synthesis and Some Properties of Polyhedral Graphite

We have applied laser vaporization to grow carbon materials and describe a novel synthesis of polyhedral graphite (PG) particles. This synthesis is based on the condensation of carbon vapor confined by high-pressure Ar gas. We used a CO2 laser (10.6 micrometer and 5-kilowatt peak power) with a pulse duration of 500 ms. The laser beam was focused onto a graphite target through a ZnSe window in a cylindrical stainless-steel chamber filled with Ar gas at 8 x 10(exp 5) Pa. The laser spot size and power density on the target were adjusted to 2 millimeters and 30 kilowatts per square centimeter, respectively. After laser irradiation of several shots on the fresh surface of a rotating graphite target, the deposits produced on the chamber wall were collected. SEM, TEM, Raman scattering spectroscopy, and powder XRD investigation of the deposited particles demonstrated that this laser vaporization method produces PG with a high yield (greater than 90%) and without hollow cavities in their centers. Faceted PG particles, ranging in size from 110 to 500 nm, have a turbostatic structure. Studies on the structure and properties, such as electrical resistance, of PG particles during high-pressure compression of the PG particles is underway.