Nitrogen diamond synthesis

Among the various compounds of carbon, the carbides of different elements have a special significance from the tribological point of view. Many of these materials, for instance WC, SiC, and TiC, are mechanically hard and have found use in the tribological industry. The carbonitride (or what can also be called the carbide of nitrogen) is an important constituent of this class of materials. In the last decade or so, the theoretical prediction of crystalline carbonitride phases that could be harder than diamond has generated much interest in the synthesis of this material. 

Carbon in the structural form of diamond is the only element used industrially as a hard material. Each year about ten tons of natural diamond and about twenty tons of synthetic diamond (produced via high temperature high pressure synthesis) are marketed as hard materials. While pure diamond is transparent, a yellow tint results from the replacement of some carbon atoms by nitrogen, and a blue, yellow, or even green tint through substitution of carbon by boron atoms. Polycrystalline diamond with impurities, used as an abrasive, is often black. 

We also performed C02-laser heating experiments on borane-dimethylamine BH3 NH(CH3)2 to check if organic materials containing boron and nitrogen can be used for synthesis of ternary BNC compounds with diamond-like structure. Borane-dimethylamine was heated at 23 GPa to about 3000 K. Raman spectra from the heated sample area revealed the presence of cubic BN, and of liquid H2 at pressures below the solidification point of hydrogen (5.5 GPa at room temperature [71]) (Fig. 17). A Raman spectrum of the recovered white agglomerate showed a weak line of diamond in addition to the Raman bands of cubic BN. Thus, borane-dimethylamine transformed to cubic BN, diamond and hydrogen... 

The invention of cubic boron nitride (CBN) is closely linked to the synthesis of artificial diamond. Cubic boron nitride synthesis was conducted first in 1957. CBN crystals are produced from boron and nitrogen at high pressures of 50-90 kbar, high temperatures between 1,800 °C and 2,700 °C, and in the presence of a catalyst (Klocke 2009). During the first years on the market, CBN was seen as a competitor to diamond. However, CBN proved to be a better material for machining of hard-to-machine ferrous materials than diamond due to the missing chemical affinity and the higher thermal stability. 

Bhattacharyya S, et al. Synthesis and characterization of highly-conducting nitrogen-doped nltrananocrystaUine diamond films. Appl Phys Lett 2001. 

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