Researchers Discover Substitutes For Rare Earth Materials In Magnets

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Researchers at the University of Cambridge, in collaboration with colleagues in Austria, report that tetrataenite, a “cosmic magnet” that takes millions of years to develop naturally in meteorites, can potentially be used instead of rare earth materials in magnets.

Previously, attempts to make tetrataenite in the laboratory have depended on extreme and impractical methods, but the researchers say they have found a way to bypass those prior techniques by using phosphorus. In a research paper published in the journal Advanced Science, they suggest there is a possibility to produce tetrataenite artificially and at scale without any specialized treatment or expensive techniques.

“Rare earth” is a misleading term that is sort of an inside joke among organic chemistry aficionados. It refers to a group of elements on the periodic table. “Noble gases” is another term that has little meaning except to organic chemists. In truth, “rare earth” elements aren’t all that rare in the grand scheme of things, but extracting them and purifying them is a challenge.

Rare Earth Materials And Permanent Magnets

The real reason why this news is important is that rare earth materials are critical to making the permanent magnets that are an essential component of the electric motors that the transition to an emissions free economy depends upon.

The sticking point is that China, with it predilection for dominating so many of the manufacturing processes for making electric vehicles, solar panels, and other critical technologies needed to address an overheating planet, controls over 80% of the world market for rare earth elements.

We know the danger of allowing tyrants in Saudi Arabia and Russia to control our access to fossil fuels. That experience suggests letting China be the gatekeeper for the new technologies we need to transfer away from relying on fossil fuels may be similarly fraught with danger in the future.

Professor Lindsay Greer of the materials science and metallurgy department at Cambridge University tells Innovation News Network, “Rare earth deposits exist elsewhere, but the mining operations are highly disruptive, as you have to extract a huge amount of material to get a small volume of rare earths. 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.”

One of the most promising alternatives for permanent magnets is tetrataenite, an iron-nickel alloy with an ordered atomic structure. The material forms over millions of years as a meteorite slowly cools. This offers the iron and nickel atoms enough time to order themselves into a particular stacking sequence within the crystalline structure, resulting in a material with magnetic properties similar to those of rare earth magnets.

In the 1960s, tetrataenite was artificially formed by blasting iron-nickel alloys with neutrons, which allowed the atoms to form the desired ordered stacking. However, this technique is unsuitable for mass production. “Since then, scientists have been fascinated with getting that ordered structure, but it’s always felt like something that was very far away,” Greer says.

Over the years, many scientists have attempted to make tetrataenite on an industrial scale, but the results have been disappointing. 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.

Taking A Closer Look

The team studied the mechanical properties of iron-nickel alloys containing small amounts of phosphorus, which is present in meteorites. Inside these materials were a pattern of phases that indicated the expected tree-like growth structure called dendrites.

“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.

Initially, the diffraction pattern of tetrataenite looks like the structure expected for iron-nickel alloys, namely a disordered crystal not of interest as a high-performance magnet. But when Ivanov looked closer, he identified the tetrataenite.

According to the team, phosphorus allows the iron and nickel atoms to move faster, enabling them to form the necessary ordered stacking without waiting for millions of years. 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 a simple casting.

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

Although the research is promising, more work is needed to decide whether it will be suitable for high performance magnets. The team is hoping to collaborate with major magnet manufacturers to determine this.

The Takeaway

Why do we write about topics that are not yet out of the laboratory stage? Because the breakthroughs happening in labs around the world today will be critical to the transition away from burning fossil fuels as the basis of the global economy and human existence.

New types of batteries that are lighter, more powerful, faster charging, less expensive, and kinder to the environment are being researched in hundreds of laboratories all around the world as you read this. We don’t know where the breakthroughs will occur but we know they will come, just as those first crude internal combustion gasoline and diesel engines became the ultra-sophisticated machines that power hundreds of millions of vehicles today.

There are electric motors that do not rely on permanent magnets, but in general they are more costly than permanent magnet motors. If there is a way to duplicate their performance with inexpensive materials that are readily available to all manufacturers without one country dominating the supply chain, that is good news for us all.

The odds are, by 2030 electric cars will have taken a quantum leap forward as more and more new innovations become commercially available. We can’t wait!

Featured image: Tetrataenite, by Rob Lavinsky (CC BY-SA 3.0)