Further Methods of Nanodiamond Preparation

One other method to generate nanoscale diamond particles has already been presented in Section 4.5.2 In the heart of very large carbon onions, a strong selfcompression reduces the interlayer distance from 0.34nm to less than 0.25 nm 

Some other methods to prepare diamond particles with diameters in the lower range of nanometers have been described, too. Just some of them shall be presented here as examples. For a comprehensive discussion refer to the speciaUzed literature given in the annexure. 

From the microwave supported plasma CVD, which is also used to deposit diamond films (Section 6.3.1), a method generating nanodiamond in a flow reactor is derived. The sole modification to obtain single particles is to omit the substrate from the reactor so the diamond particles formed are carried along by the gas current to precipitate only in cooler parts of the apparatus placed downstream after the oven. As carbon source, dichloromethane in a mixture with oxygen is employed. The main product obtained with this method is amorphous, graphitic material. This may, however, quantitatively be removed by a treatment with 70% perchloric 

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