‘Cosmic magnet’ research could reduce reliance on rare earth elements

14 Nov 2022

The material tetrataenite usually forms over millions of years as a meteorite slowly cools. Image: © Aliaksandr Marko/Stock.adobe.com

Researchers found a way to make tetrataenite, a magnetic material that usually takes millions of years to form in meteorites.

Scientists have discovered a way to develop a material found in meteorites, which could be used to create high-performance magnets without the need for rare earth elements.

High-performance magnets are vital for various technologies such as wind turbines and electric vehicles. Like many electronic devices, these currently require rare earth elements.

However, there are a number of difficulties with getting these elements. The researchers at the University of Cambridge said China has a “near monopoly” on global production. This creates concerns as any geopolitical issues could drastically affect supply.

Prof Lindsay Greer, who led the research, said rare earth deposits do exist elsewhere, but the mining operations to acquire them are “highly disruptive”.

“You have to extract a huge amount of material to get a small volume of rare earths,” Greer said. “Between the environmental impacts, and the heavy reliance on China, there’s been an urgent search for alternative materials that do not require rare earths.”

From millions of years to seconds

Working with colleagues from Austria, the researchers believe to have found a possible replacement – developing a new approach for making tetrataenite, a ‘cosmic magnet’ that takes millions of years to develop naturally in meteorites.

As a meteorite slowly cools, the iron and nickel atoms within order themselves into a particular stacking sequence in the crystalline structure, which results in a material with magnetic properties similar to those made with rare earth elements.

The researchers said previous attempts to make tetrataenite in laboratory conditions have relied on impractical methods that would not be suitable for mass production.

Greer and her team believe the solution has been found in phosphorus, an element that is also sometimes found in meteorites that contain iron and nickel alloys.

They discovered that phosphorus allows the iron and nickel atoms to move faster, letting them form the necessary stacking much faster.

By mixing iron, nickel and phosphorus in the right quantities, the researchers said they were able to speed up tetrataenite formation so much that it forms over a few seconds in simple casting.

“What was so astonishing was that no special treatment was needed: we just melted the alloy, poured it into a mould, and we had tetrataenite,” Greer said.

“The previous view in the field was that you couldn’t get tetrataenite unless you did something extreme, because otherwise, you’d have to wait millions of years for it to form.

“This result represents a total change in how we think about this material.”

The research team has filed a patent application for the technology and plans to work with major magnet manufacturers to confirm whether this tetrataenite approach will be suitable for high-performance magnets.

The team said their work could also force a revision on whether tetrataenite really does take millions of years to form naturally in meteorites.

The research was supported in part by the European Research Council under the EU’s Horizon 2020 research and innovation programme and Seventh Framework Programme. Further support came from the Austrian Science Fund.

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Leigh Mc Gowran is a journalist with Silicon Republic