Rare earth element (noun, “RAIR UHRTH ELL-eh-ment”)
A rare earth element is one of 17 elements on the periodic table. These 17 metals include 15 “lanthanides.” Those are elements 57 to 71. Scandium (element 21) and yttrium (element 39) are also rare earths.
Rare earth elements are not really that rare. They’re found around the world. Some are as common in Earth’s crust as copper or tin. But rare earth elements are only found in very low concentrations. They are usually mixed with each other or other elements. And they’re hard to separate and purify. So miners have to extract lots of ore to get even a little bit of a rare earth element.
That effort is well worth it, though, because rare earth elements are crucial for building a lot of technology. They’re key ingredients in smartphones and electric cars, as well as medical devices, wind turbines and much more.
Rare earth elements are so useful thanks to their electrons. Each atom of a rare earth element has a special group of electrons called f-electrons. These electrons can release energy in the form of very specific colors of light. Terbium, for instance, emits a precise color of green light. Meanwhile, europium can give off red or blue. Such elements give rise to colors on phone, computer and TV screens.
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The rare earth elements yttrium and neodymium give off other types of light. These are useful for making high-power lasers that can cut through steel or remove tattoos. The rare earth element erbium emits the right kind of light to boost signals through fiber optic cables. Those cables bring internet to many parts of the world.
Rare earth elements’ f-electrons also bestow these materials with powerful, reliable magnetism. The rare earth element neodymium is used to make magnets that vibrate inside headphones to generate sounds. Such magnets also make it possible to read and write data on hard drives, and they create magnetic fields inside fMRI machines.
Adding the rare earth element dysprosium to the mix makes those magnets more heat-resistant. As a result, they become useful parts for electric vehicles. Rare earth elements even magnetically levitate some trains to glide above their tracks, leading to smoother, faster rides.
Other rare earth elements play important roles in energy production. The catalyst cerium helps turn crude oil into useful products. Gadolinium absorbs neutrons to rein in energy production inside nuclear reactors.
With such a wide variety of highly important jobs, rare earth elements are in high demand. And that demand is only expected to increase. This is motivating scientists to find new ways to more easily recycle these precious materials.
In a sentence
Even though rare earth elements are key to many green technologies, the process of mining and purifying these materials causes a lot of pollution.