What are rare earths and what are they used for?

Rare earth elements aren’t really rare on our planet. But they can be hard to find in large, mineral-form quantities that are economically worth developing.

While rare earth mineral deposits have been mined from the US to Brazil and India to South Africa, the lion’s share — more than 95 percent — of today’s supplies come from China. That’s become a growing concern as China has rolled out production caps and quotas.

Why? Because rare earth metals are currently crucial for making a variety of high-tech products, including lasers, lighting, superconductors and advanced batteries.

Of the 17 rare earth elements, five have been identified as “critical” by the US Department of Energy (DOE), both in terms of their importance to clean-energy technologies and in their vulnerability to supply risks. These include:

  • Yttrium – A key material in phosphors for compact fluorescent lightbulbs (CFLs), televisions and liquid crystal display (LCD) screens. Demand for yttrium could rise even higher, the DOE says, “if high-temperature superconductors begin to capture market share from permanent magnets used in other applications such as wind turbines.” Furthermore, no effective substitute materials are currently known for yttrium.
  • Dysprosium – A soft, silvery metal with “extremely high magnetic strength,” says the DOE. “Although used in relatively small quantities in magnets, it is crucial for magnets capable of high-temperature operations (particularly in vehicle drives).” With the push to promote electric cars, demand for dysprosium is likely to keep going up. And, for now, the only known substitute is the even more rare and more expensive terbium.
  • Europium – Used in phosphor compounds that produce the white light of compact fluorescent lightbulbs. With CFL use on the rise, especially in places like Europe that are phasing out inefficient incandescents, Europium demand is expected to keep rising. There are no proven substitutes that work in CFLs, according to the DOE assessment.
  • Terbium – Also used as a phosphor in fluorescent lighting. Terbium can also be used in magnets for electric motors, but not as often as dysprosium, which is less expensive. Ongoing advances in light-emitting diodes (LEDs) could eliminate the need for terbium in such uses, “but not until at least the medium term,” says the DOE.
  • Neodymium – In clean energy technologies, used mostly to produce high-strength permanent magnets for hybrid and electric cars and for wind turbines. Neodymium is also used in combination with other elements to color glass and ceramics, and to produce glass lasers and astronomical instruments.

Two other rare earths have “near-critical” status in the DOE’s 2011 “Critical Materials Strategy”: cerium (used in nickel metal hydride batteries and phosphor powders for CFLs) and lanthanum (he lightest rare earth element, used mainly in battery alloys). The rest — including erbium, gadolinium, holmium,  lutetium, praseodymium, promethium, samarium, scandium, thulium and ytterbium — are either considered “not critical” or did not make the DOE’s list.

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