University of Cambridge researchers have found a fresh approach to developing a potential substitute for rare earth magnets.
A new discovery
Tetrataenite, a “cosmic magnet” that naturally forms in meteorites over millions of years, has been discovered by researchers at the University of Cambridge and their Austrian counterparts to potentially replace rare earth magnets.
The utilization of the common element phosphorus by the researcher will replace previous attempts to create tetrataenite in the lab, which relied on radical and unworkable procedures. Tetrataenite can be manufactured artificially and on a large scale using phosphorus, without the need for costly or specialized procedures.
The journal Advanced Science has published an article titled “Direct production of hard-magnetic tetrataenite in bulk alloy castings.” The Austrian Academy of Sciences and Cambridge Enterprise, the University’s commercialization arm, have submitted a patent application for the technology.
Why must a rare earth magnet replacement be sought?
High-performance magnets are required to create a zero-carbon economy. The greatest permanent magnets on the market right now are made of rare earth elements, which, despite their name, are present in large quantities in the Earth’s crust.
However, because China controls the majority of world production, guaranteeing a consistent supply of rare earth is a challenge. According to research, China supplied 81% of the rare earth used in the world in 2017. Other nations, including Australia, mine REEs, although the existing supply of rare earth may be in jeopardy due to rising geopolitical tensions with China.
“Rare earth reserves exist elsewhere, but the mining operations are highly disruptive, as you have to extract a vast amount of material to produce a little volume of rare earth,” said Professor Lindsay Greer from Cambridge’s Department of Materials Science & Metallurgy. There has been a pressing search for substitute materials that do not require rare earth because of the negative environmental effects and our significant reliance on China.
What are the current issues with tetrataenite production?
Tetrataenite, an iron-nickel alloy with an organized atomic structure, is one of the most promising substitutes for permanent magnets. As a meteorite cools gradually over millions of years, the material develops. This provides the iron and nickel atoms with sufficient time to arrange themselves into a certain stacking sequence within the crystalline structure, resulting in a substance with magnetic properties comparable to those of rare earth magnets.
Tetrataenite was created intentionally in the 1960s by bombarding iron-nickel alloys with neutrons, which caused the atoms to arrange themselves into the desired ordered stacking. This method can’t be used for mass production, though.
Since then, Greer, who also oversaw the research, said, “scientists have been obsessed with creating that ordered structure, but it’s always felt like something that was very far away.”
Numerous researchers have tried unsuccessfully throughout the years to produce tetrataenite on an industrial basis.
Using phosphorous as a potential alternative for tetrataenite production
Now, Greer and his colleagues from the Austrian Academy of Sciences, and the Montanuniversität in Leoben, have found a potential alternative that avoids these extreme methods.
“For most people, it would have ended there: nothing interesting to see in the dendrites, but when I looked closer, I saw an interesting diffraction pattern indicating an ordered atomic structure,” said first author Dr. Yurii Ivanov, who completed the work while at Cambridge and is now based at the Italian Institute of Technology in Genoa.
They were able to accelerate tetrataenite formation by between 11 and 15 orders of magnitude by mixing iron, nickel, and phosphorus in the right quantities.
This meant the material was able to form over a few seconds in simple casting.
“What was so astonishing was that no special treatment was needed.
This result represents a total change in how we think about this material.”
Future work with magnet manufacturers
Although this approach appears promising, additional research is necessary before determining whether it will work with high-performance magnets. To find out, the team is aiming to work with significant magnet producers.
The findings of this study may alter opinions of how long tetrataenite takes to grow.
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