DST Seminar: Nitrogen aggregation in diamond - Matthew Dale, De Beers Technologies
1-2pm Monday 26th November
Materials & Analytical Sciences 2.06
Nitrogen is the most commonly identified impurity in diamond. When diamond is annealed with sufficient temperature, various species become mobile and single nitrogen substitutional atoms aggregate into larger complexes. Understanding and controlling this process is significant to engineering defects into diamond, such as the nitrogen-vacancy centre, as well as understanding the differences between natural and synthetic diamond. Irradiation prior to annealing increases the aggregation rate; this is caused by both vacancies and interstitials mediating the mobility of nitrogen. In this presentation I will talk about the migration of vacancies and interstitials and their role in enhancing the aggregation process. I will highlight differences between aggregation in natural, HPHT and CVD grown diamond. Finally, I will explain how these differences can be used to effectively distinguish natural from synthetic diamond and their use in De Beers’ screening instruments.