Two Kinds Of Rare Earth Magnets

Rare earth magnets were not developed until the 1970’s. Researchers were looking for materials that would constitute the primary matter in newer, stronger magnets that they could use to increase industrial output and also use in the increasing number of electronic devices demanded by the world’s population.  These materials, it was hoped, would possess stronger magnetic fields and resist demagnetization better than ferrite and alnico magnets, which were the most commonly used magnetic materials up through the middle of the 20th century.

The samarium cobalt magnet was the first such magnet ever developed. As its name indicates, it was composed of the rare earth samarium and cobalt. The appellation of rare earth is a misnomer. These materials are actually fairly common, if hard to reach. However, this new type of magnet was superior to previously invented magnets in most every area of performance. Unfortunately, they were also brittle and easily suffered fractures. While they found immediate and easy use in industry, researchers immediately set out to create a magnet that would be stronger in every way and also resist chipping.

They were not completely satisfied with the development of the neodymium magnet. While this was eventually to become the leader among all rare earth magnets, at the outset it disappointed in one crucial area. Neodymium magnets were generally superior or equal to all previous magnet models, including those made from samarium cobalt, in magnetic strength and in their general resistance to demagnetization. However, the Curie temperature of this magnet was abysmally low, meaning that it began to lose its magnetic qualities long before other magnets. This made it virtually useless for many applications which would occur in the presence of high temperatures.

Eventually, this flaw was overcome. Researchers were too tantalized by the promising strength of this substance in every other area of magnetic strength to surrender to its apparently inherent inability to handle the stress of heat. In order to raise its Curie temperature, a useful neodymium magnet must be allowed with other rare earths which lend it resistance to high temperatures. The true strength and value of neodymium magnets is, then, determined by the quality of the alloy made with these other rare earths.


The possible applications of rare earth magnets of any kind are numerous. The most common applications are in computer hard drives. It would be easy to say that the evolution of magnet technology has gone hand in hand with much of the technological revolution seen in the last few decades. Magnets made from such materials are also used to make turbines, stereo electronics, cordless tools and roller coasters. Slowly but surely, magnets made from rare earths are replacing the older forms of magnets in nearly every conceivable application.

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