Magnets play an important role in modern technology: they are found in computer hard drives, magnetic separators, 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, many high-tech products would be unthinkable.
The problem 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 an almost monopoly on certain materials and can control trade in them accordingly.
Alternatives for neodymium and dysprosium
For this reason, researchers are now looking for alternatives to neodymium and the like: could strong permanent magnets be created that make do with more readily available rare-earth or perhaps even contain no metal from this group at all? Thomas Lograsso from the Ames Laboratory of the US Department of Energy and his colleagues have now addressed this question – and initially focused on paramagnets. These materials are weakly attracted to magnetic fields but are not permanently magnetized.
“We can rehabilitate such systems, so to speak, and turn them into a magnet 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 we are looking for?
Two promising candidates
To identify promising candidates, the scientists used a computational approach. In this way, they were able to predict the magnetic behavior of a variety of materials and also find out whether they are suitable for the development of solid magnets. “This approach led to the identification of some powerful magnets very quickly,” the team writes.
The calculations showed, among other things, that the paramagnetic cerium cobalt CeCo3 can be transformed 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. True, 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 the like, however, it is readily available and easy to obtain.
“Being able to replace rare earth metals, which are in high demand and in short supply, would make sense from both an economic and ecological point of view,” says Lograsso. “Although our modified cerium-cobalt compounds are not yet as powerful as the strongest rare earth magnets, 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 rare earth metals. Among other things, they are experimenting with cobalt to give the iron germanium Fe3Ge a strong magnetization. (American Chemical Society, 2019; Meeting)
Source: American Chemical SocietyApril 2, 2019