With global supplies and costs of rare earths becoming a serious concern among various industries, here's a lowdown on what makes these elements so special
Most REEs are not as rare as the name suggests.
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Rare earth elements (REEs) are a set of 17 metallic elements that include the 15 lanthanides on the periodic table, plus scandium and yttrium. REEs are varyingly abundant in the earth’s crust. For instance, cerium is the 25th most abundant element of the 78 common elements (60 parts per million), while thulium and lutetium are the least abundant (about 0.5 part per million). REEs are iron gray to silvery lustrous metals, are typically soft, malleable, and ductile and usually reactive, especially at higher temperatures or when finely divided.
Most REEs are not as rare as the name suggests. These elements were named ‘rare-earth elements’ because most were identified during the 18th and 19th centuries as “earths”, which originally meant they are materials that could not be changed further by increasing their temperature. In comparison to other “earths”, such as lime or magnesia, they are relatively rare. Except promethium, all REEs are more abundant in the earth’s crust than silver, gold, or platinum. However, concentrated and mineable deposits of REEs are unusual.
REEs have a wide range of uses, and form important components of more than 200 products, especially high-tech consumer products, such as mobile phones, computer hard drives, electric and hybrid vehicles, and flatscreen monitors and televisions. Defence applications—like electronic displays, guidance systems, lasers, and radar and sonar systems—also use REEs.
Although a very small amount of REEs may be used in any of these products, it can be critical for its functioning. For instance, REE magnets (which are permanently magnetised) are stronger per unit weight and volume than any other magnet type. Each magnet can be made of multiple kinds of REEs. REEs are used in the small magnets that make it possible for spindle motors and voice coils of desktops and laptops to function.
Also read: Rare earths: Strategic metals key to future technologies