Manufacture of gem quality diamonds: a review

• Published in: Ceramics international Vol. 26; no. 1; pp. 73 - 85
• Main Authors: Choudhary, Devashish, Bellare, Jayesh
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 2000; Elsevier Science
• Subjects: Cross-disciplinary physics: materials science; rheology; CVD; Exact sciences and technology; Fullerenes and related materials; diamonds, graphite; High pressure; Materials science; Microwave; Physics; Seeds; Specific materials; CVD; Microwave; Seeds; High pressure; Crystal growth; Fabrication; Solvents; Thermodynamics; Reviews; Catalysts; Synthetic diamond; Kinetics; High temperature
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/S0272-8842(99)00022-X

Gem quality diamonds have been grown using high temperature, high pressure processes like the solvent catalyst method and the temperature gradient method. This review with 64 references focuses on the thermodynamics, kinetics of the growth processes and the apparatus used to grow diamonds. Gem quality diamonds can be synthesized by the high pressure, high temperature process, either by the solvent catalyst method or the reconstitution technique. The Hall belt apparatus and the toroid anvil are the commonly used equipment to generate high pressures. In the high pressure, high temperature processes a catalyst is essential for synthesis. The commonly used catalysts are Fe, Co and Ni whereas recently hydroxides and carbonates have also been used to synthesize diamond. Surface chemistry plays an important role in determining the quality of the crystal. If the carbon flux to the nucleating diamond exceeds a certain limit, graphite nucleates instead of diamond. Temperature, pressure and impurities like nitrogen and boron also affect the quality and growth rates of the synthesized diamond. High growth rates have also been observed if substantial amount of paramagnetic nitrogen is dispersed in the reaction bath. Recent developments of growing diamond by chemical vapour deposition techniques like microwave plasma and hot filament technique have been reviewed. Non-destructive, optical methods to characterize diamonds have been briefly described. ©