Scientists have successfully synthesized sizable meteorite diamonds, also known as lonsdaleite or hexagonal diamond, a material predicted to be up to 50% harder than conventional Earth diamonds. This breakthrough, achieved using a high-pressure, high-temperature technique, produced tiny disks of this ultrahard diamond, potentially paving the way for its use in advanced industrial applications such as drilling tools and electronics.

Diamonds are renowned as the hardest naturally occurring substance. Their crystal structure is cubic. However, a subtly different structure, hexagonal diamond, was proposed in the 1960s, with small, impure crystals of this structure subsequently discovered in meteorites like the Canyon Diablo, which impacted the Arizona desert approximately 50,000 years ago. Unlike the cubic structure of conventional diamond, lonsdaleite contains two different bond lengths, theorized to boost its hardness by as much as 58%. The challenge has been preparing sufficiently large samples of this hexagonal form for analysis, coupled with doubts about its existence due to contamination with other carbon forms in original meteorite samples.

Inspired by a fragment of the Canyon Diablo meteorite containing lonsdaleite, likely formed under the intense pressures and temperatures of an Earth impact, a team led by Wenge Yang at the Center for High Pressure Science and Technology Advanced Research in Beijing aimed to replicate these conditions in the lab. They developed a high-pressure, high-temperature synthesis using a diamond anvil cell. Starting from purified graphite, they carefully compressed the material, fixing the shifted atoms in place with targeted laser heating. Once these distorted tetrahedra of hexagonal diamond formed, the team slowly released the pressure to ensure the new crystal did not spontaneously revert to graphite.

Regional Perspective

This global scientific advancement marks a significant step in materials science. While the production of pure and larger samples is still under development, the ability to create hexagonal diamond in a lab opens new avenues for innovation in fields like advanced electronics, quantum technology, thermal management systems, and precision machinery. These applications may take up to a decade to fully materialize, but the research is laying the groundwork for the next generation of ultrahard materials with potential industrial adoption.

Analysis

The synthesis of hexagonal diamond is a notable scientific achievement, offering a material with potentially superior hardness compared to conventional diamonds. Dr. Soumen Mandal, a physicist at the University of Cardiff not involved in the study, commented that it is "a good first demonstration," emphasizing the need for pure crystals and larger quantities to fully explore its physical, mechanical, thermal, and electrical properties. Although hardness testing requires larger samples, the team confirmed the new material is at least as tough as regular diamonds. Researchers are hopeful that future experiments will enable the production of larger, purer crystals, potentially facilitating industrial adoption within a decade, particularly in precision machinery and high-performance electronics.