The structure of liquid carbon elucidated by in situ X-ray diffraction.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 40399671.
- Also identified by DOI 10.1038/s41586-025-09035-6 and PMC identifier 12158773.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Carbon has a central role in biology and organic chemistry, and its solid allotropes provide the basis of much of our modern technology<sup>1</sup>. However, the liquid form of carbon remains nearly uncharted<sup>2</sup>, and the structure of liquid carbon and most of its physical properties are essentially unknown<sup>3</sup>. But liquid carbon is relevant for modelling planetary interiors<sup>4,5</sup> and the atmospheres of white dwarfs<sup>6</sup>, as an intermediate state for the synthesis of advanced carbon materials<sup>7,8</sup>, inertial confinement fusion implosions<sup>9</sup>, hypervelocity impact events on carbon materials<sup>10</sup> and our general understanding of structured fluids at extreme conditions<sup>11</sup>. Here we present a precise structure measurement of liquid carbon at pressures of around 1 million atmospheres obtained by in situ X-ray diffraction at an X-ray free-electron laser. Our results show a complex fluid with transient bonding and approximately four nearest neighbours on average, in agreement with quantum molecular dynamics simulations. The obtained data substantiate the understanding of the liquid state of one of the most abundant elements in the universe and can test models of the melting line. The demonstrated experimental abilities open the path to performing similar studies of the structure of liquids composed of light elements at extreme conditions.