RARE-EARTH FREE MAGNETS
Tohoku U team produces rare-earth-free Fe-Ni magnet
by Charles Morris / December 4, 2015
“High-performance magnets, which are critical for EV motors, typically depend on rare earth elements such as samarium, neodymium and dysprosium. These exotic materials are not only costly, but also present environmental and political challenges. Researchers from Tohoku University in Japan recently succeeded in producing a completely rare-earth-free high-quality magnet made of iron and nickel. The team, led by Professor Akihiro Makino, describes its work in “Artificially produced rare-earth free cosmic magnet,” published in Nature’s Scientific Reports. It has long been known that small amounts of Fe-Ni magnets are found in certain meteorites. These natural magnets are produced by a process of extremely slow cooling – about one Kelvin per million years. Until recently, it was considered impossible to produce these structures artificially in a short time. Makino’s group has succeeded in producing such a magnet by using high atomic diffusivity at low temperatures, reducing the time scale from billions of years to just a couple of days. The paper likens the process to “travelling in a time machine.” The results of the study offer a solution for the development of next-generation hard magnetic materials, because the alloys are free from rare-earth elements, and the technique is well suited for mass production. “The realization of hard magnets free of rare-earth metals may help in resolving the global issues of resource exhaustion, which should become critical in the near future,” writes Makino. “The successful synthesis of the chemically ordered L10 FeNi phase is one step closer to the field of materials science for realizing a safe and sustainable society.”
New approach to ‘cosmic magnet’ manufacturing could reduce reliance on rare earths in low-carbon technologies
by University of Cambridge / October 24, 2022
“Researchers have discovered a potential new method for making the high-performance magnets used in wind turbines and electric cars without the need for rare earth elements, which are almost exclusively sourced in China. A team from the University of Cambridge, working with colleagues from Austria, found a new way to make a possible replacement for rare-earth magnets: tetrataenite, a “cosmic magnet” that takes millions of years to develop naturally in meteorites. Previous attempts to make tetrataenite in the laboratory have relied on impractical, extreme methods. But the addition of a common element—phosphorus—could mean that it’s possible to make tetrataenite artificially and at scale, without any specialized treatment or expensive techniques. The results are reported in the journal Advanced Science. A patent application on the technology has been filed by Cambridge Enterprise, the University’s commercialization arm, and the Austrian Academy of Sciences.
High-performance magnets are a vital technology for building a zero-carbon economy, and the best permanent magnets currently available contain rare earth elements. Despite their name, rare earths are plentiful in Earth’s crust. However, China has a near monopoly on global production: in 2017, 81% of rare earths worldwide were sourced from China. Other countries, such as Australia, also mine these elements, but as geopolitical tensions with China increase, there are concerns that rare earth supply could be at risk. “Rare earth deposits exist elsewhere, but the mining operations are highly disruptive: you have to extract a huge amount of material to get a small volume of rare earths,” said Professor Lindsay Greer from Cambridge’s Department of Materials Science & Metallurgy, who led the research. “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.”
Tetrataenite, an iron-nickel alloy with a particular ordered atomic structure, is one of the most promising of those alternatives. Tetrataenite forms over millions of years as a meteorite slowly cools, giving the iron and nickel atoms enough time to order themselves into a particular stacking sequence within the crystalline structure, ultimately resulting in a material with magnetic properties approaching those of rare-earth magnets. In the 1960s, scientists were able to artificially form tetrataenite by bombarding iron-nickel alloys with neutrons, enabling the atoms to form the desired ordered stacking, but this technique is not suitable 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,” said Greer. Despite many attempts over the years, it has not yet been possible to make tetrataenite on anything approaching an industrial scale.
Now, Greer and his colleagues from the Austrian Academy of Sciences and the Montanuniversität in Leoben, have found a possible alternative that doesn’t require millions of years of cooling or neutron irradiation. The team were studying the mechanical properties of iron-nickel alloys containing small amounts of phosphorus, an element that is also present in meteorites. The pattern of phases inside these materials showed 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. At first glance, the diffraction pattern of tetrataenite looks like that of the structure expected for iron-nickel alloys, namely a disordered crystal not of interest as a high-performance magnet. It took Ivanov’s closer look to identify the tetrataenite, but even so Greer says it’s strange that no one noticed it before.
The researchers say that phosphorus, which is present in meteorites, allows the iron and nickel atoms to move faster, enabling them to form the necessary ordered stacking without waiting for millions of years. By mixing iron, nickel and phosphorus in the right quantities, they were able to speed up tetrataenite formation by between 11 and 15 orders of magnitude, such 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 mold, and we had tetrataenite,” said 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.” While the researchers have found a promising method to produce tetrataenite, more work is needed to determine whether it will be suitable for high-performance magnets. The team are hoping to work on this with major magnet manufacturers. The work may also force a revision of views on whether the formation of tetrataenite in meteorites really does take millions of years.”
Tetrataenite, by Rob Lavinsky
MAKING COSMIC MAGNETS
Researchers Discover Substitutes For Rare Earth Materials In Magnets
by Steve Hanley / October 29, 2022
“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. 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. 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.
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.”
SYNTHETIC RARE EARTH ELEMENTS
Researchers aim to solve the rare earths crisis
by Tanner Stening / October 18, 2022
“During a time of immense global uncertainty, managing supply chains for critical materials has been a top priority for many governments and large organizations. But what happens when certain materials are concentrated in the hands of one single nation—as most of the world’s rare earth metals are with China? Rare earth elements are essential in manufacturing a range of high-tech devices. In particular, they are used in the production of high-performance magnets that are, themselves, fundamental components in a whole host of technologies. For years, researchers have been searching for new magnetic materials that can act as substitutes for the critically scarce components. Engineers at Northeastern now believe they can solve the puzzle, and have patented a process to accelerate the creation of one such rare earth magnet alternative—a mineral known as tetrataenite, whose magnetic properties make it a leading candidate to replace magnets made of the scarce material.
The problem is that tetrataenite isn’t found in nature—at least, not on Earth. It’s only found in meteorites, says Laura Lewis, a university distinguished professor of chemical engineering at Northeastern, who is part of a team that is attempting to make tetrataenite in a lab in an effort to uncover scalable solutions to the rare earths shortage. To make the cosmic mineral requires manipulating the atomic structures of its iron and nickel components by arranging them into a crystal structure that resembles tetrataenite, speeding up a natural process that would take millions of years on Earth, Lewis says. “The iron and nickel atoms have to rearrange themselves. And nature will do it, but it will take millions of years to do,” she says. “So if we can do it in industrially relevant time-scales, we will have a nice new addition to the permanent magnet portfolio.” Decoupling the scarce materials from magnet production not only provides sorely needed supply chain relief—there simply aren’t enough magnets to meet the world’s energy needs—but, Lewis says, it will help “rebalance geopolitical tensions” by easing U.S. dependence on Chinese rare earths. China controls close to 80% of the world’s rare earths supply.
But when it comes to these precious metals, scarcity alone doesn’t tell the whole story. “It’s beyond just scarcity,” Lewis says. “Because the methods necessary to process the ore that comes out of the earth are really environmentally hazardous—I would say even damaging. And for many decades, China not only has had a large supply of these rare earths, but the means and will to produce them.” She says that while China has been using rare earths to meet the needs of its own green revolution, its virtual monopoly presents an obstacle to other nations looking to get their hands on the materials. According to one estimate, global demand for these magnets is expected to reach $37 billion by 2027. “Whatever they [the Chinese] do to meet their own needs is going to be at the expense of whatever the rest of the world needs,” Lewis says. Far from your average refrigerator magnets, industrial permanent magnets are used to transfer energy from mechanical to electrical sources.
The list of technologies that rely on magnetic flux (a technical term describing the magnetic force exerted on a surface when a magnet interacts with it) is virtually endless, from electrical cars and wind turbines to computer hard drives, speakers and military radars, among many others devices and applications. “They’re absolutely everywhere,” Lewis says. “Once you start pulling things apart, you’re going to find them everywhere.” Lewis and her team are tasked with “discover[ing] nature’s rules for creation of competitive magnetic materials comprised of non-critical elements.” The team has been engaged in the research for several years now, Lewis says, adding that they’ve arrived at “very promising results.” Lewis is also a delegate to two U.S. technical advisory groups representing the American National Standards Institute in the International Standards Organization. The advisory groups she contributes to focus on managing the supply chains for critical elements linked not just to rare earths, but also materials such as lithium that are used in both household and industrial technologies. “I’ve been meeting with my counterparts in China, Japan, Korea, Australia, and Europe to figure out how to fix these supply chains,” Lewis says.”
Toxic cleanup technique can get more rare earth metals out of ores
by John Timmer / 11/3/2022
“A variety of modern technologies, including permanent magnets that have been used in everything from earbuds to wind turbines, rely on rare earth elements. While the metals aren’t actually especially rare, they don’t occur at high concentrations in the Earth’s crust. As such, extracting them is expensive and tends to produce a lot of environmental damage, meaning that most of the supply comes from a small number of countries (see the chart here), leaving the supply at risk of political fights. So the potential to get much more out of existing rare earth mines is obviously very appealing. And the method described in a paper released on Monday seems to offer it all: more metal per ore, much lower cost, and far less worry about mining waste. Many of the best rare earth deposits occur in places where nature has concentrated the elements for us. These tend to be sediments formed from materials where the rare earth elements will react or interact with the sediment, coming out of solution and gradually building up the concentration in the ore. The usual method of extracting the elements from these ores essentially involves reversing that process.
“China’s Bayan Obo mine produces about half the world’s supply of rare earth elements.”
An ion-rich solution is pumped through the ore, and these ions displace the rare earths, allowing them to leach out of the ore. Typically, the solution used is ammonium sulfate. The production of ammonium sulfate has its own energy and materials costs, and it leaves the material behind in the ore, which may require an environmental cleanup afterward. And the process isn’t very selective; lots of other, cheaper metals, like aluminum and calcium, also come out of the ore and need to be separated from the desired products. The idea behind the new work was to use an electrical current to simplify the process. The standard leaching relies on the flow of an ion-rich solution through the ore to move the rare earth elements out of it. But once that solution displaces these elements from the ore, they return to being ions in a solution. In that state, an electrical current should drive them to the oppositely charged electrode. In theory, this should mean that less of the leaching solution is needed to get material out of the ore, and thus there should be fewer environmental issues afterward. This sort of electricity-driven purification has been used to decontaminate soils with high levels of metals. But it’s not been tried on this sort of mining before. The idea worked even better than the researchers expected.
The basic procedure was pretty straightforward. Samples of rare earth ore were saturated with the same leaching solution that would normally be used to extract the metals. At this point, instead of just adding more solution, an electric current was applied. Over time, some of the metals migrated to the negative electrode; the amounts collected there were compared to the known contents of the ore. In the first run, done on a sample of ore that could fit on a lab bench, the results were promising. The efficiency of metal extraction was 84 percent, or more than double what could be obtained by leaching. Because the materials were being actively pushed to the collection point, it only took about a third of the time to reach that level of purification, and only a small fraction of the leaching solution was needed. Surprisingly, the contamination by other metals was also a third of the normal volume. The researchers figured out what happened to these contaminants, and it turned out to vary. Some ions, like potassium, only carry a single positive charge while in solution, so they move more slowly than rare earth elements, which have multiple positive charges. The fact that water was split at the electrodes also had an effect. Some metal ions reacted with oxygen to form negatively charged ions that migrated in the opposite direction. Others reacted with hydroxide ions and precipitated out of solution.
The net result was simply lower contamination levels, meaning the rare earth metals were of much higher purity. So the researchers scaled up the test, working on a 20-kilogram sample of ore. That actually worked even better, requiring less leaching solution and lower currents to work. Here, rare earth extraction cleared 90 percent efficiency, taking 67 hours to get there. By contrast, leaching didn’t max out until 130 hours after extraction started, and its maximum efficiency was only 60 percent. Again, the extraction that used electricity had fewer contaminating metals. At that point, the researchers went to an actual mine and got a 14-ton sample of ore. To power their experiment, they simply threw a handful of solar panels on top of it. Leaching solution was added to the ore until the electrical resistance dropped and remained stable. While they didn’t collect the extracted metals, the researchers sampled through the pile of ore afterward and found both that the rare earth elements had been depleted and that the contamination from the leaching solution was low enough that no environmental cleanup would be needed. That plays a role in their estimations of the cost of the procedure.
For normal leaching, the single biggest cost is the environmental cleanup, which accounts for nearly two-thirds of the expense. When electrical-driven purification is used, that cost would go away. As a result, the predicted cost of producing 2,000 tonnes of rare earth oxides from ore drops from $52 million to under $19 million. Obviously, electrical use goes up, but not by a huge amount. The researchers estimate that the extraction process requires less than a third of a kilowatt-hour for each cubic meter of ore—within a range they expect can easily be provided by some solar panels. The cost estimates, however, don’t really get into the details of what is needed to scale this process up to industrial production levels, which may require a significant amount of additional or modified hardware—not to mention batteries if this is going to run off of solar power. Still, the approach’s savings are pretty substantial, and its use would mean far less mining per rare earth materials produced. So if it does work anywhere near as well as this paper suggests, it’s hard to imagine that it wouldn’t pay off given enough time.”
Nature Sustainability, 2022. DOI: 10.1038/s41893-022-00989-3