Alternative magnets against the lack of raw materials

New materials will replace magnets made of scarce rare earth metals

Hard disks, but also many other electronic components can not do without rare earth magnets. © Kerrik / istock
Read out

Instead of neodymium and Co: New magnetic materials could replace high-tech magnets made of rare-earth metals in the future. Researchers have already identified the first compounds that can be strongly magnetized by the addition of substances such as magnesium or cobalt. These materials could be a real alternative to rare earth permanent magnets such as neodymium - reducing the demand for these scarce resources.

Magnets play an important role in modern technology: they are used in computer hard drives, power generators and many other electronic components. The secret of the strongest magnets available today are often called rare earths. Metals such as neodymium and dysprosium have special electrical and magnetic properties - without them, many high-tech products would be unthinkable.

The problem is that these coveted commodities are scarce and expensive, but the demand is growing. Scientists are already predicting future bottlenecks for some of the rare earth metals. On the other hand, geopolitical aspects also play a role. For example, as the main exporter of rare earths, China has almost a monopoly on certain materials and can control its trade accordingly.

Alternatives for neodymium and dysprosium

For this reason, researchers are now looking for alternatives for neodymium and Co: Could you create strong permanent magnets that get along with better available rare earths or perhaps even no metal from this group included? Thomas Lograsso from the US Department of Energy's Ames Laboratory and his colleagues have dedicated themselves to this question, focusing initially on paramagnets. These materials are weakly attracted to magnetic fields but are not permanently magnetized.

"We can, so to speak, rehabilitate such systems and turn them into magnets by adding certain materials, " explains Lograsso. "That's why we start with alloys or compounds that have the right properties to be ferromagnetic at room temperature." But which fabrics have the features you're looking for? display

Two promising candidates

To identify promising candidates, the scientists used a computer-based approach. In this way, they were able to predict the magnetic behavior of a variety of materials and also find out if they are suitable for the development of solid magnets. "This approach has quickly led to the identification of some powerful magnets, " the team writes.

The calculations showed, among other things, that the paramagnetic cerium cobalt CeCo3 can be transformed into a ferromagnet by the addition of magnesium. And indeed, subsequent experiments confirm this, as Lograsso and his colleagues report. Another candidate identified in the analyzes is CeCo5. This material is already a strong ferromagnet. The calculations and experiments revealed, however, that this property can be further optimized with the right amount of copper and iron.

"Economically and ecologically sensible"

With these additions, CeCo5 could someday even replace strong rare earth magnets such as neodymium and dysprosium, the researchers predict. The advantage: Strictly speaking, cerium is also a member of the rare earth class. Unlike Neodymium and Co, however, it is abundantly available and easy to obtain.

"Replacing the high-demand and scarce rare-earth metals would make sense from an economic as well as an ecological point of view, " says Lograsso. "While our modified cerium-cobalt compounds are not as powerful as the strongest rare-earth magnets, they may still be a valuable alternative for certain applications."

In addition, he and his colleagues are already working on alternative magnets that are not based on cerium or other metals from the rare earth class. Among other things, they experiment with cobalt in order to give the iron germanium Fe3Ge a strong magnetization. (American Chemical Society, 2019; Meeting)

Source: American Chemical Society

- Daniel Albat