Lecture in Materials 7: Dan Belnap "HPHT diamond sintering and nanodiamond manufacturing"

Utah is responsible for the genesis of an important group of materials known as polycrystalline diamond (PCD) manufactured at high pressures and high temperatures (HPHT). University of Utah graduate H. Tracy Hall (Ph.D. 1948 under Henry Eyring) pioneered the synthesis of PCD using conditions of 6.5 GPa and 2200°C at a small company now known as MegaDiamond (Hall H T, Sintered Diamond, a Synthetic Carbonado, Science, (1970) 169, 868-869). PCD has since evolved into a multibillion USD industrial material used worldwide in critical and diverse applications ranging from oil and gas drilling to aerospace. In addition to MegaDiamond, two other Utah-based companies (US Synthetic and PreCorp) are part of the worldwide group of over 20 companies supplying PCD. The scientific principles involved in high pressure sintering of diamond materials will be discussed, as well as a brief overview of the resulting structure and properties.
Diamond is known to have over 500 color centers, of these the single nitrogen + vacancy (NV) optical center has received by far the most technological interest. The negatively-charged NV center contains two unpaired electrons and forms an optically-readable qubit, which is capable of room-temperature spin manipulation by low energy microwave radiation thereby making it useful for applications such as quantum computation and sensing. In particular, NV nanodiamond has been shown to be an effective intracellular biosensor to detect properties such as temperature, strain, E/M field, pH, and chemical potential (Zhang, et al, “Toward Quantitative Biosensing w/ Nitrogen Vacancy Center in Diamond, ACS Sens. 2021, 6, 2077-2107). MegaDiamond has developed a patented/patent pending HPHT process to make high-quality nitrogen vacancy nanodiamond and is working with multiple university collaborators, including the University of Utah. The HPHT process used to manufacture NV nanodiamond will be discussed, as well as a brief overview of its emerging applications.