Rare earth magnets are rare

Alternative magnets against the lack of raw materials

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 adding substances such as magnesium or cobalt. These materials could be a real alternative to permanent magnets made from rare earths such as neodymium - and thus reduce the demand for these scarce raw materials.

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

The problem with this is that these coveted raw materials are scarce and expensive, but 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. As the main exporter of rare earths, China has a near monopoly on certain materials and can control trade in them accordingly.

Alternatives to neodymium and dysprosium

For this reason, researchers are now looking for alternatives to neodymium and Co: Could one create strong permanent magnets that get by with more readily available rare earths or perhaps even do not contain any metal from this group? Thomas Lograsso from the Ames Laboratory of the US Department of Energy and his colleagues have now addressed this question - initially focusing on paramagnets. These materials are weakly attracted by magnetic fields, but are not permanently magnetized.

“We can rehabilitate such systems, so to speak, and transform them into magnets by adding certain materials,” explains Lograsso. “To do this, we start with alloys or compounds that have the right properties to be ferromagnetic at room temperature.” But which materials have the properties you are looking for?

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 large number of materials and also find out whether these are suitable for the development of solid magnets. “This approach quickly identified some powerful magnets,” the team writes.

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

"Economically and ecologically sensible"

With these additives, CeCo5 could one day even replace strong rare earth magnets such as neodymium and dysprosium, the researchers predict. The advantage of this: Strictly speaking, cerium also belongs to the class of rare earths. Unlike neodymium and co, however, it is abundantly available and easy to procure.

"To be able to replace the rare earth metals, which are in high demand and in short supply, would make sense from both an economic and an ecological point of view," says Lograsso. "Our modified cerium-cobalt compounds are not yet as powerful as the strongest rare earth magnets, but they could still represent 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. For example, they are experimenting with cobalt to give the iron germanium Fe3Ge a strong magnetization. (American Chemical Society, 2019; Meeting)

Source: American Chemical Society

2nd April 2019

- Daniela Albat