50,000-year-old meteorite could revolutionize electronics and fast-charging

The "Diablo Canyon" meteorite is a gift from the past.
Christopher McFadden
Cut and polished section through the meteorite.James St. John/Wikimedia Commons

Scientists have discovered a fascinating, intricate tiny structure that has never been observed before while examining diamonds inside of an old meteorite.

According to researchers, the structure, which is an interlocking form of graphite and diamond, has special qualities that one day might be utilized to create faster charging or new kinds of electronics.

The "Diablo Canyon" meteorite, as it is called, struck Earth about 50,000 years ago and was initially found in Arizona in 1891. This meteorite is composed of ~90% kamacite, ~1-4% taenite, and up to 8.5% troilite-graphite nodules (FeS & C). The original mass has been estimated to be 100 feet across and about 60,000 tons.

The strange diamond structures are thought to have formed and been locked into the meteorite during this event. 

This meteorite contains diamonds, although not the common varieties. Most diamonds form nearly 90 miles (150 kilometers) below Earth's surface, where temperatures can reach more than 2,000 degrees Fahrenheit (1,093 degrees Celsius). The temperature and pressure at this depth cause the carbon atoms to arrange themselves into cubic shapes. 
In contrast, the diamonds found inside the "Canyon Diablo" meteorite have a hexagonal crystal structure and are known as lonsdaleite (named after British crystallographer Dame Kathleen Lonsdale, the first female professor at University College London). These kinds of crystals, it has been discovered, can only form at incredibly high pressures and temperatures.

Scientists have replicated similar structures, but they are usually only found in meteorites

Scientists have successfully made lonsdaleite in a lab — using gunpowder and compressed air to propel graphite disks 15,000 mph (24,100 km/h) at a wall — lonsdaleite is usually formed only when asteroids strike Earth at enormously high speeds.

With regards to the "Diablo Canyon" meteorite diamonds, the scientists noticed an unusual phenomenon while analyzing the lonsdaleite in the meteorite. For example, they discovered growths of another carbon-based substance called graphene interacting with the diamond instead of the pure hexagonal formations they had anticipated.

These growths, called diaphites, take the appearance of an especially fascinating layered pattern inside the meteorite. "Stacking faults" between these layers indicate that the layers do not line up precisely, according to the researchers' statement.

The discovery of diaphites in meteoritic lonsdaleite raises the possibility that this resource is widely accessible because it can be found in other carbonaceous materials, according to the researchers' findings. The discovery also improves the researchers' understanding of the temperatures and pressures required to build the structure.

Graphene is made of a one-atom-thick sheet of carbon, arranged in hexagons. The material has numerous potential applications, even if research on it is still in its early stages.

It could one day be used for more precise medical treatments, smaller electronics with lightning-fast charging speeds, or faster and bendier technology, the researchers said, because it is both as light as a feather and as strong as a diamond, transparent and highly conductive, and 1 million times thinner than a human hair.

canyon diablo meteorite
The outside surface of the meteorite. Source: Geoffrey Notkin/Wikimedia Commons

Since these graphene growths were found inside meteorites, researchers may now learn more about how they arise and, consequently, how to create them in a laboratory.

"Through the controlled layer growth of structures, it should be possible to design materials that are both ultra-hard and also ductile, as well as have adjustable electronic properties from a conductor to an insulator," Christoph Salzmann, a chemist at University College London and co-author of a paper describing the research, said in the statement

The strange new structures were described on July the 22nd, 2022 in the journal Proceedings of the National Academy of Sciences.

Study abstract:

"Studies of dense carbon materials formed by bolide impacts or produced by laboratory compression provide key information on the high-pressure behavior of carbon and for identifying and designing unique structures for technological applications. However, a major obstacle to studying and designing these materials is an incomplete understanding of their fundamental structures. Here, we report the remarkable structural diversity of cubic/hexagonally (c/h) stacked diamond and their association with diamond-graphite nanocomposites containing sp3-/sp2-bonding patterns, i.e., diaphites, from hard carbon materials formed by shock impact of graphite in the Canyon Diablo iron meteorite. We show evidence for a range of intergrowth types and nanostructures containing unusually short (0.31 nm) graphene spacings and demonstrate that previously neglected or misinterpreted Raman bands can be associated with diaphite structures. Our study provides a structural understanding of the material known as lonsdaleite, previously described as hexagonal diamond, and extends this understanding to other natural and synthetic ultrahard carbon phases. The unique three-dimensional carbon architectures encountered in shock-formed samples can place constraints on the pressure-temperature conditions experienced during an impact and provide exceptional opportunities to engineer the properties of carbon nanocomposite materials and phase assemblages."

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