An Asteroid Collision With Earth 50,000 Years Ago Formed Diamonds With Unique Properties

Scientists have found that diamonds formed during a high-energy shock wave resulting from an asteroid collision 50,000 years ago have unique and exceptional properties.

According to the researchers, the diamonds can be used for advanced mechanical and electronic applications. They can be used to design materials that are not only ultra-hard but also malleable with tunable electronic properties. | Representative Photo

Asteroids colliding with Earth result in shockwaves which create materials with a range of complex carbon structures. According to a study led by researchers at University College London and Hungarian scientists, these materials could be used for advancing future engineering applications.

The scientists have found that diamonds formed during a high-energy shock wave resulting from an asteroid collision 50,000 years ago have unique and exceptional properties. The diamonds are unique because they were formed by short-term high temperatures and extreme pressure. The study describing the findings was recently published in the Proceedings of the National Academy of Sciences.

What Can These Diamonds Be Used For?

According to the researchers, the structures can be used for advanced mechanical and electronic applications. They can be used to design materials that are not only ultra-hard but also malleable with tunable electronic properties. A malleable substance is one that can easily be changed into a new shape. 

What Is Lonsdaleite?

An international team of scientists used detailed state-of-the-art crystallographic and spectroscopic examinations of the mineral lonsdaleite from the Canyon Diablo iron meteorite. Lonsdaleite is also known as hexagonal diamond in reference to the crystal structure, and is a stronger and stiffer naturally occurring substance than diamond. The Canyon Diablo iron meteorite was first found in 1891 in the Arizona desert. 

Lonsdaleite was named after the pioneering British crystallographer Professor Dame Kathleen Lonsdale, the first female professor at University College London. 

Earlier, lonsdaleite was thought to consist of pure hexagonal diamond. This made it different from the classic cube diamond. The researchers later found that lonsdaleite is composed of nanostructured diamond and graphene-like intergrowths, a term used to refer to two minerals in a crystal growing together. The nanostructured diamond and graphene-like intergrowths in lonsdaleite are called diaphites. The researchers identified stacking faults, or "errors" in the sequences of the repeating patterns of layers of atoms. 

Why Is The Study Important?

In a statement released by University College London, Dr Péter Németh, the lead author on the paper, said through the recognition of the various intergrowth types between graphene and diamond structures, one can get closer to understanding the pressure-temperature conditions that occur during asteroid impacts. 

According to the study, the distance between the graphene layers was found to be unusual due to the unique environments of carbon atoms occurring at the interface between diamond and graphene. The researchers showed that the diaphite structure is responsible for a previously unexplained spectroscopic (relating to the structures of atoms and molecules) feature. 

Chris Howard, a co-author on the paper, said this is very exciting since researchers can now detect diaphite structures in diamond using a simple spectroscopic technique without the need for expensive and laborious electron microscopy. Spectroscopy is used as a tool for studying the structures of atoms and molecules. 

The structural units and the complexity reported in the lonsdaleite samples can occur in a wide range of other carbonaceous materials that are formed by shock and static compression or by deposition from the vapour phase, according to the scientists. Vapour phase deposition is a process in which a material transitions from a condensed phase to a vapour phase and then back to a thin film condensed phase.

In the statement, Professor Christoph Salzmann from University College London said that the discovery has opened the door to new carbon materials with exciting mechanical and electronic properties that may result in new applications ranging from abrasives and electronics to nanomedicines and laser technology.

In this way, the study draws attention to the exceptional mechanical and electronic properties of the carbon structures of lonsdaleite.