Mechanism of Hexagonal Diamond Formation from small molecules with heavy atoms doping

Lonsdaleite, also named hexagonal diamond (HD) is of interest due to its potentially superior hardness over cubic diamond (CD), yet its synthesis remains challenging. Recent studies have formed nearly pure HD from graphite under extreme conditions, but alternative pathways are needed.
We explore HD formation from small-molecule precursors doped with heavy atoms. Under high-temperature and high-pressure (HTHP) conditions, adamantane transforms into cubic nanodiamonds, but doping with silicon or germanium yields a HD-CD mixture, suggesting a distinct mechanism.
To further investigate, we propose synchrotron X-ray diffraction to analyze the structural transition from molecular precursors to HD. This study could enhance synthesis strategies and broaden HD applications.