Bulk hexagonal diamond
Nature • • technology
Key Points:
- Lonsdaleite, a hexagonal polymorph of diamond, has been studied extensively since the 1960s, with early works identifying its presence in meteorites and its potential superior hardness compared to cubic diamond.
- Recent research using advanced techniques such as ultrafast X-ray diffraction, transmission electron microscopy, and machine learning simulations has provided new insights into the formation mechanisms and structural characteristics of lonsdaleite and related carbon phases.
- Shock compression experiments reveal that graphite can transform into both diamond and lonsdaleite on nanosecond timescales, highlighting complex phase transition pathways influenced by pressure, temperature, and structural defects.
- Some studies challenge the existence of lonsdaleite as a discrete material, suggesting it may be faulted
