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--2200ppm, 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--1.3wt.%, the nitrogen concentration in the diamond almost remains in a nitrogen concentration range from 1250ppm to 2200ppm, 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.