The carbon allotrope glitter as n-diamond and i-carbon nanocrystals

In the carbon science literature

CASTEP) [9] shows it to be metallic, like the observed electrical characteristics of these carbon forms.In this Letter, we report on a comparison of the diffraction pattern observed for nanocrystalline ndiamond and i-carbon forms by these investigative teams, with the calculated diffraction pattern of glitter based upon lattice parameters optimized using the DFT-CASTEP method [11].The close fit of the latter dataset to that observed for n-diamond and i-carbon, as reported herein, suggests that indeed i-carbon may be of the same structure as n-diamond, and that they both may have the tetragonal glitter structure.
Table 1 reports the theoretical diffraction pattern for the glitter allotrope of carbon [12], using the DFT optimized lattice parameters described above, as shown in columns 1 & 2 [11].The Bragg spacings for glitter were calculated with the standard crystallographic formula for the tetragonal crystal system, as reported by Warren et al. and

shown in
Equation (1).[12] In column 3 of the table is reported the combined diffraction pattern for the n-diamond C form, labeled as (n) [5], and the icarbon C form, labeled as (i) [1].Column 4 reports the absolute deviation (∆d) between the observations and the theoretical diffraction data for the glitter model, and the percentage absolute deviation (∆d/d (x) 100) can be derived from this data.Table 2 reports the DFT optimized geometry of the glitter model.
There are 10 diffraction observations for n-diamond [5], and 9 diffraction observations for i-carbon [1], in the reported datasets.There are thus 2 outliers that have been omitted from the comparison shown in 1, with the n-diamond dataset having an outlier at 0.2060 nm [5] (ascribed to the cubic diamond (111) reflection), and the i-carbon dataset having an outlier at 0.2120 nm (also ascribed to the cubic diamond (111) reflection).
Analysis over the other 17 observations in the combined n-diamond [5] and i-carbon [1] datasets, shows that the DFT optimized glitter model fits these 17 observations with an average percentage deviation (%d) of 1.41% (98.59% agreement between the model and the n-diamond and i-carbon experimental dataset).
It is believed that the uncertainties associated with recording electron diffraction data from carbon nanocrystals, in the work on n-diamond [5] and i-carbon [1] described here, is within a 2% uncertainty, and we believe here that the glitter model [10] is thus a reasonable explanation for the numerous observations of kinetically stabilized C forms reported in the literature as ndiamond and i-carbon.