Ultrananocrystalline Diamond in the Laboratory and the Cosmos

Diamond is one of the most intriguing and potentially useful materials known to science. It is the hardest substance that we know, and it has the highest sound velocity and the highest thermal conductivity of any material. Because diamond is so difficult to fabricate, the challenge is to take meaningful advantage of its extraordinary properties. The chemical vapor deposition (CVD) of diamond overcomes many of the fabrication problems and has become the focus of an important research and development effort worldwide. Although the General Electric Corp. succeeded about 50 years ago in the synthesis of diamond by high-pressure, high-temperature techniques, the low-pressure, or CVD, methods were developed only about 20 years ago in the former Soviet Union, Japan, and the United States. This presentation will deal with a more recent development in diamond CVD that allows one to control the crystallite size in such a way as to synthesize phase-pure nanocrystalline diamond films, which have many unique and fascinating properties not shared by other forms of diamond.