Rare Earth Magnets Powering Today’s New Technologies
Magnets used in iPods and smartphones, to cars and guitars
In the 1960’s, US military scientists discovered that some Rare Earth Elements (REEs) have incredibly powerful magnetic properties. During the 1970s and 80s, a variety of alloys made from REEs were developed that proved to be substantially stronger than conventional ferrite or alnico magnets.
Two types of Rare Earth magnets became common: neodymium magnets and samarium-cobalt magnets. Neodymium and samarium are both Light Rare Earth Elements (LREEs). Magnet makes frequently use other Rare Earths – the LREE praseodymium and two Heavy Rare Earths, dysprosium and terbium – to improve the properties of neodymium magnets.1
The Rare Earths (REs) are ferromagnetic, which means they are like iron and can be magnetized. Their crystalline structures also allow the crystal of the material to be easily magnetized in one particular direction, while resisting being magnetized in any other direction.
REEs in their pure form only exhibit their magnetic properties at low temperatures, so they are mixed with other metals such as iron, nickel and cobalt, to allow the magnetic properties to exhibit at and above room temperature.
The first practical RE magnets to be developed were samarium-cobalt magnets. They were also the first type of RE magnet to be commercialized. They are weaker than other RE magnets and more expensive to produce. They do, however, operate at a higher temperature and so are used in applications where higher temperatures are expected.
Neodymium magnets pack the most power
Neodymium magnets were discovered in 1982, by General Motors, Sumitomo Special Metals and the China Academy of Science. They were developed in response to the high price of samarium-cobalt magnets, and they are now the strongest and cheapest of the RE magnets. Neodymium magnets have also the highest magnetic field strength, which allows for the use of smaller magnets.
Typically made up of an alloy of neodymium, iron and boron, these magnets are commonly found in computer hard drives, audio speakers and headphones. They are also used in a wide range of green energy, communications, and advanced technology applications, such as smart phones, electric and hybrid cars, and wind power generation.
Other places you’ll find RE magnets are in magnetic resonance imaging equipment, superconductors, fuel cell systems, magnetic motors in cordless tools, and electric guitar pickups. Experiments are ongoing on magnetic levitation, and these magnets are also being investigated by the roller coaster industry.
Because they are so strong, it is important to handle these magnets with care. Even small RE magnets can cause injuries such as seriously pinched and even crushed fingers. 2 The magnets have also been known to erase certain data discs and credit card information. While loaded with magnetic strength, these magnets are typically brittle and are often coated and given protective treatments such as gold, nickel and zinc plating to prevent corrosion and chipping.3
Prices for REEs used in Rare Earth magnets have risen dramatically in recent months because of increasing demand and reduced supply from China, by far the world’s largest producer of REEs. This upward surge is expected to continue: in a report released last December, the U.S. Department of Energy estimated that widespread use of electric-drive vehicles and offshore wind farms could cause shortages of these REEs by 2015.4 While researchers are now working on new types of nanostructured magnets that would use smaller amounts of Rare Earths than standard magnets,5 it is clearly imperative for our greener future that magnet manufacturers are able to secure alternate sources of Rare Earths.
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1, 4 New Magnets Could Solve Our Rare-Earth Problems
2Ingested Magnets Can Cause Serious Intestinal Injuries
3 Rare-earth magnet
5 The Rare-Earth Crisis