What happened
Scientists used shock waves to subject diamond samples to extreme compression. The experiments were reported to reach pressures of around 1 terapascal, which is about ten million times atmospheric pressure.
The reported sequence of observations was:
Crystal structure stability: Under the high-pressure conditions, diamond was reported to remain in its existing crystal structure rather than transform into a different crystal structure during the high-pressure phase.Melting into a new state: After the high-pressure phase, diamond was reported to later melt into a metallic liquid.Pressure–melting trend: As pressure increased, diamond’s melting point was reported to decrease slightly.
Background and earlier position
Materials under extreme pressure can undergo phase changes. For diamond, such changes can include melting into a liquid and possible pressure-driven crystal-structure transformations (a change in how carbon atoms are arranged within the solid). Because carbon-bearing materials are relevant to planetary interiors and high-pressure laboratory environments, checking whether diamond-like structures persist or transform under extreme compression is important for building credible models.