A New Dopant of NaN3 for High-Concentration-Nitrogen Diamond Synthesized by HPHT

Nitrogen is successfully doped in diamond by adding sodium azide (NaN3) as the source of nitrogen to the graphite and iron powders. The diamond crystals with high nitrogen concentration, 1000–2200 ppm, which contain the same concentrations of nitrogen with natural diamond, have been synthesized by using the system of iron-carbon-additive NaN3. The nitrogen concentrations in diamond increase with the increasing content of NaN3. When the content of NaN3 is increased to 0.7–1.3 wt.%, the nitrogen concentration in the diamond almost remains in a nitrogen concentration range from 1250 ppm to 2200 ppm, which is the highest value and several times higher than that in the diamond synthesized by a conventional method without additive NaN3 under high pressure and high temperature (HPHT) conditions.