Abstract: After the synthesis of new-diamond by using a method of catalyzed carbon black, the crystal structure of the new-diamond after various aging-treatment time was investigated by X-ray diffraction(XRD). The XRD patterns indicate that the newdiamond was a metastable phase, and the crystal structure of the new-diamond changed with the variation of the aging-treatment time at room temperature. Based on the XRD analysis and simulated XRD pattern,
a“defective diamond”model with a fractional occupation site was proposed
to explain the time-dependent the variation of the new-diamond crystal structure. In this model, the zero occupancy corresponds to a face-central cubic(FCC) crystal, while full occupation leads to a perfect diamond. A density functional theory computation further confirms the trend of increasing the
stability during the evolution from FCC to diamond structure within our model.
Therefore, we suggest that n-diamond is indeed an intermediate state between the FCC structure and diamond structure.

Key words: New-diamond, XRD, Density function theory