New method to produce 'space magnets' without the need for rare earths

Researchers have discovered a potential new method for making high-performance magnets used in wind turbines and electric cars without the need for rare earth elements, which are almost exclusively supplied by China.

A research team from the University of Cambridge (UK), in collaboration with colleagues from Austria, has found a new method to replace rare earth magnets. That is Tetrataenite , a type of "cosmic magnet" that takes millions of years to grow naturally in meteorites.

The new method promises the potential to make high-performance magnets without the need for rare earths, a material of which China accounts for more than 80% of the global supply.

Previous attempts to create Tetrataenite in the lab have relied on extreme, impractical methods. In the new method, however, the researchers added a common element, phosphorus , to create Tetrataenite on a large scale and artificially without any specialized treatments or expensive techniques.

The research results were published in the journal Advanced Science. Cambridge Enterprise, the commercialization arm of the University of Cambridge, and the Austrian Academy of Sciences have now filed a patent application for the technology.

High performance magnets are a key technology for building a carbon-free economy and the best permanent magnets available today contain rare earth elements.

Despite their name, rare earths are abundant in the Earth's crust . However, China has a near-monopoly on global production of these materials . In 2017, 81% of the world's rare earths originated in China.

Other countries, such as Australia, also mine rare earths, but there are concerns that rare earth supplies could be at risk if geopolitical tensions with China escalate.

'Rare earth deposits that exist elsewhere are very difficult to mine: you have to mine a large amount of material to get a small amount of rare earth,' said Professor Lindsay Greer from the University of Cambridge's Department of Materials Science & Metallurgy.

Mr Greer also said that given the environmental impact and over-reliance on China, there was an urgent search for alternative materials that did not require rare earths.

Tetrataenite, an iron-nickel alloy with a uniquely ordered atomic structure, is one of the most promising alternatives. Tetrataenite forms over millions of years as a meteorite slowly cools, giving the iron and nickel atoms time to arrange themselves into a unique chain in the crystal structure, eventually creating a material with magnetic properties similar to those of rare-earth magnets.

Meteorites, where Tetrataenite magnets form over millions of years under natural conditions.

In the 1960s, scientists were able to create artificial tetrataenite by bombarding iron-nickel alloys with neutrons, allowing the atoms to arrange in the desired order, but this technique was not suitable for mass production.

Now, Greer and his colleagues from the Austrian Academy of Sciences and the Montanuniversität University in Leoben have found a viable alternative that does not require millions of years of cooling or neutron irradiation.

The team of scientists studied the mechanical properties of an iron-nickel alloy containing small amounts of phosphorus – an element also found in meteorites.

The researchers say that phosphorus, which is present in meteorites, allows the iron and nickel atoms to move faster, allowing them to form the necessary ordered mass without having to wait millions of years. By mixing iron, nickel and phosphorus in the right amounts , they were able to speed up the formation of Tetrataenite by 11 to 15 orders of magnitude, so that it formed in a matter of seconds in a simple structural process.

'What's amazing is that there's no special processing required: we just melted the alloy, poured it into a mold, and we got tetrarataenite,' said Greer. 'The previous view in the field was that you couldn't get tetrarataenite unless you did something extreme, because otherwise you'd have to wait millions of years for it to form. This represents a complete change in the way we think about this material.'

While the researchers have found a promising method for producing Tetrataenite, more research is needed to determine whether it is suitable for high-performance magnets. The team hopes to work with major magnet manufacturers on this.