What Is a Rare Earth Magnet and Do Samarium Cobalt and Neodymium Identify as Such?

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rare earth elements periodic chartThere are seventeen rare earth elements – fifteen of which are lanthanides and two of which are transition metals, yttrium and scandium – that are found with lanthanides and are chemically similar. Samarium (Sm) and Neodymium (Nd) are the two most commonly used rare earth elements in magnetic applications. More specifically, Samarium and Neodymium are light rare earth elements (LREE) in the cerium earths group. Samarium Cobalt and Neodymium alloy magnets provide some of the best force-to-weight ratios for industrial and commercial applications.

Neodymium vs. Rare Earth Elements

The rare earth elements are typically found together in the same mineral deposits, and these deposits are plentiful. With the exception of promethium, none of the rare earth elements are especially rare. For example, samarium is the 40th most plentiful element found in the Earth’s mineral deposits. Neodymium, like other rare earth elements, occurs in small, less accessible ore deposits. However, this rare earth element is nearly as common as copper and more plentiful than gold.

In general, rare earth elements were given their name for two different, yet significant reasons. The first possible naming derivation relies on the initial perceived scarcity of all seventeen rare earth elements. The second suggested etymology stems from the difficult process of separating each rare earth element from its mineral ore.

Neodymium Rare Earth Magnet SquareThe relatively small and difficult to access ore deposits containing rare earth elements contributed to the initial naming of the seventeen elements. The term “earths” simply refers to naturally occurring mineral deposits. The historical scarcity of these elements made its namesake inevitable. Currently, China meets approximately 95% of global demand for rare earths – mining and refining around 100,000 metric tons of rare earths a year. The United States, Afghanistan, Australia, and Japan also have significant rare earths reserves.

The second explanation for rare earth elements being designated “rare earth” was due to difficulty in both the mining and refining processes, which was typically done by crystallization. The term “rare” is historically synonymous with “difficult.” Because their mining and refining processes were not simple, some experts suggest the term “rare earth” was applied to these seventeen elements as a result.

Samarium Cobalt magnetsSamarium Cobalt Rare Earth Magnets and Neodymium rare earth magnets are neither prohibitively expensive nor in short supply. Their label as “rare earth” magnets should not be a primary reason to either select or discount these magnets from industrial or commercial applications. Potential use of either of these magnets should be carefully measured according to intended usages, and according to variables like heat tolerances. The designation of magnets as “rare earth” also allows for a general categorization of both SmCo magnets and Neo magnets together when mentioned alongside traditional Alnico magnets or Ferrite magnets.


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Magnets in the News: Rare Earth Metals a Last Minute Deletion from China Tariff List

According to The New York Times, recent tariffs imposed on imported goods from China are meant to pressure the country to change its current trade practices that are negatively impacting American businesses. However, as the deadline approached for the final agreement in late September 2018, the US administration decided to remove nearly 300 product lines from the list due to specific objections by American companies. One of the product lines deleted from the list of tariffs was rare earth metals. Rare earth elements are currently used in myriad products worldwide including magnets, radar, high tech products, vehicles, and more....

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Thermal Cycling: Effect of Temperature on Rare Earth Magnets

Many times, we are asked about the effects of thermal cycling on rare earth permanent magnets, but there is not a simple rule of thumb to offer. From a first order standpoint, thermal cycling will degrade the performance of rare earth Neodymium Iron Boron and Samarium Cobalt magnets. There are two primary mechanisms which drive this degradation. One occurs quickly, and the second occurs over a long period of time...

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