New method of producing “cosmic magnets”, no need for rare earths

New method of producing “cosmic magnets”, no need for rare earths

Researchers have discovered a potential new way to make high-performance magnets used in wind turbines and electric cars without the need for the rare earth element, which is almost exclusively supplied by China. Country.

A research team from the University of Cambridge (UK), in collaboration with colleagues from Austria, has found a new way to replace rare earth magnets. It’s tetrataenite, the “cosmic magnet” that takes millions of years to develop naturally in meteorites.

Previous attempts to create tetrataenite in the laboratory have relied on extreme, impractical methods. In the new method, however, the researchers have added a common element, phosphorus, to create tetrataenite on a large scale and artificially without the need for any specialized treatments or other chemicals. expensive technique.

The results of the study were published in the journal Advanced Science. Cambridge Enterprise, the commercial branch of the University of Cambridge, and the Austrian Academy of Sciences, have now applied for a patent on the technology.

The new method holds the promise of making high-performance magnets without the need for rare earths, for which China accounts for more than 80 percent of the global supply.

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

Unlike their name, rare earths are abundant in the Earth’s crust. However, China has a near monopoly on the global production of this material. In 2017, 81% of rare earths worldwide originated in China.

Other countries, such as Australia, also mine rare earths, but there are concerns that rare earth supplies could be at risk in the event of increased geopolitical tensions with China.

Professor Lindsay Greer, from the University of Cambridge’s Department of Materials Science & Metallurgy, said: “Rare earth deposits that exist elsewhere are very difficult to exploit: you have to extract large quantities of material to get one. small volume of rare earths”.

Mr. Greer also said that, in light of the environmental impact and overreliance on China, there was an urgent search for alternative materials that did not require rare earths.

Tetrataenite, an iron-nickel alloy with a specially 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 enough time to arrange themselves into a particular sequence in the crystal structure, eventually creating a magnetic material. properties similar to rare earth magnets.

Meteorite, where tetrataenite magnets have been formed 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 the technique was not suitable. for mass production.

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

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

The phosphorus, present in meteorites, allows the iron and nickel atoms to move faster, allowing them to form the necessary orderly mass without waiting millions of years, the researchers say. 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 forms in seconds in a simple process.

“What’s amazing is that there’s no special treatment: we just melt the alloy, pour it into a mold and we’ve got tetrataenite,” says Greer. The previous view in the field was that you couldn’t get tetrataenite unless you did something extreme, because otherwise you would have to wait millions of years for it to form. This result represents a complete change in the way we think about this material.”

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

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