Diamond formation by thermal activation of graphite

Synthetic diamond is used in applications ranging from abrasives, tool coat ings, bearing surfaces, microelectronics and optics to techniques to produc e diamond as the thermodynamically stable form(3), but it can also be grown at low pressures as a metastable carbon phase(1,2). Here we report the pro duction of high-purity cubic diamond microparticles (10-100 mu m), which fo rm in a highly concentrated carbon-vapour phase, followed by deposition of the crystals on the substrate, The carbon-vapour phase is generated by ther mal activation of graphite, and the fast initial growth-rates of diamond, i n the range 100-500 mu m s(-1), are at least two orders of magnitude higher than previously reported(1,2). We expect that tuning of experimental param eters to optimize the density of the carbon-vapour phase will allow us to g row larger diamond crystals, thereby opening a wider range of potential pra ctical applications.