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Making diamonds in minutes at room temperature

River of Diamond

The pictures of the RMIT team showed that the ordinary diamonds are only formed in the middle of these Lonsdaleite veins under this new method developed by the interinstitutional team. Credit: RMIT

An international research team has defied nature to produce diamonds in minutes in a laboratory at room temperature ̵

1; a process that usually requires billions of years, enormous amounts of pressure and super-hot temperatures.

The team led by The Australian National University (ANU) and RMIT University made two types of diamonds: the kind found on an engagement ring and another type of diamond called Lonsdaleite, which is found in nature at the site of meteorite impacts like Canyon Diablo in the United States.

One of the lead researchers, ANU professor Jodie Bradby, said their breakthrough shows that Superman may have had a similar trick up his sleeve when he crushed coal into diamond without using his heat beam.

Natural diamonds are usually formed over billions of years, about 150 kilometers deep in the Earth, where there are high pressures and temperatures above 1,000 degrees Celsius, ”Said Professor Bradby of the ANU Research School of Physics.

Professor Jodie Bradby

ANU professor Jodie Bradby has the diamond anvil that the team used to make the diamonds in the laboratory. Credit: Jamie Kidston, ANU

The team, including former ANU PhD scholar Tom Shiell now at the Carnegie Institution of Science, previously only created Lonsdaleite in the laboratory at high temperatures.

This new unexpected discovery shows that both Lonsdaleite and ordinary diamond can also be formed at normal room temperatures by simply applying high pressures – equivalent to 640 African elephants on the tip of a ballet shoe.

“The twist in the story is how we apply the pressure. In addition to very high pressures, we allow carbon to experience something called ‘displacement’ – which is like a twisting or sliding force. We believe this allows carbon atoms to move into place to form Lonsdaleite and ordinary diamond, ”said Professor Bradby.

Co-lead researcher Professor Dougal McCulloch and his team at RMIT used advanced electron microscopy techniques to capture solid and intact slices from the experimental samples to create snapshots of how the two types of diamonds were formed.

“Our images showed that the common diamonds are only formed in the middle of these Lonsdaleite veins under this new method developed by our inter-institutional team,” said Professor McCulloch.

Brenton Cook and Dougal McCulloch

PhD teacher Brenton Cook (left) and Prof Dougal McCulloch with one of the electron microscopes used in the research. Credit: RMIT

“Seeing these little ‘rivers’ of Lonsdaleite and ordinary diamond for the first time was just amazing and really helps us understand how they can be formed.”

Lonsdaleite, named after the crystallographer Dame Kathleen Lonsdale, the first woman chosen as a fellow of the Royal Society, has a different crystal structure than ordinary diamond. It is predicted to be 58 percent harder.

“Lonsdaleite has the potential to be used to cut through ultra-solid materials at mining sites,” said Professor Bradby.

“Creating more of this rare but super useful diamond is the long-term goal of this work.”

Ms. Xingshuo Huang is an ANU PhD teacher working in Professor Bradby’s laboratory.

“Being able to make two types of diamonds at room temperature was exciting to achieve for the first time in our laboratory,” said Ms. Huang.

The team, which involved the University of Sydney and the Oak Ridge National Laboratory in the United States, published the research results in the journal Little.

Reference: “Study of room temperature formation of the ultra-hard nanocarbon diamond and Lonsdaleite” by Dougal G. McCulloch, Sherman Wong, Thomas B. Shiell, Bianca Haberl, Brenton A. Cook, Xingshuo Huang, Reinhard Boehler, David R. McKenzie and Jodie E Bradby, 4 November 2020, Little.
DOI: 10.1002 / smll.202004695

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