FORMATION OF COMPRESSED AND MIXED-LAYERED GRAPHITE ON HEATING IMPACT DIAMONDS

作者：Gromilov S A^*; Nikolaev R E; Cherepanova S V

来源：Journal of Structural Chemistry, 2018, 59(2): 355-364.

DOI：10.1134/S0022476618020142

• impact diamond
• diamond
• lonsdaleite
• graphite
• compressed graphite
• mixed-layered graphite
• turbostratic disordering
• simulation

The graphitization process of impact diamonds in the helium atmosphere at 1900-1960 degrees C is investigated. It is shown that when an impact diamond particle with a large number of lonsdaleite defects is kept at 1900 degrees C for 1 min, similar to 5 wt.% of graphite are formed (in the paralle experiment with a particle without lonsdaleite defects the graphite formation is not observed). With an increase in the temperature to 1930 degrees C and 1940 degrees C. the graphite amount increases to 70 wt.% and 80 wt.% respectively. In both cases, a mixture of two graphite phases forms: the first is turbostratic graphite with d(002) = 3.38 degrees C; the second is compressed graphite with d(002) = 3.21 angstrom. On heating a particle to 1960 degrees C graphite is formed in which the layer packing contains a large amount of defects and is a mixture of 2H and 3R polytypes (the ratio 40: 60) with a small degree of turbostratic disordering.

• 出版日期2018-3