Ultrahard diamond single crystals from chemical vapor deposition

Gem-sized single crystals of diamond have been produced by very high growth rate microwave plasma chemical vapor deposition (CVD) and found to exhibit remarkable mechanical properties. The as-grown material has extremely high fracture toughness, and treatment by high-pressure/high-temperature annealing produces crystals that have exceptionally high intrinsic hardness. The annealing appears to induce a novel work hardening of CVD single-crystal diamond. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.