ChemMatters - December 2016

OU MAY NOT SEE THEM, BUT

they are all around you. Called rare-
earth elements, 17 silvery metals
are in nearly every high-tech prod-
uct that is a part of our modern lives. Smart-
phones and some baseball bats are stronger
and lighter because they contain an element
called scandium. The green color of a foot-
ball field on a television screen is created by
another little-known element called terbium.

Batteries that power windmills, cars, and electric guitars use neodymium, lanthanum, and other rare-earth elements.

If you could see them, it would be tough to tell rare-earth metals apart. Most were discovered in minerals unearthed from the same little town in Sweden, and they look and act so much alike chemically that it took a century to separate them from one another. But each rare-earth element has its own atomic number. These atomic numbers are: 21 (scandium), 39 (yttrium), and 57–71

(a series of elements, called the lanthanides,

usually listed in their own row in a periodic table of the elements; see sidebar). Also, because they strengthen other metals, they are essential in building smaller and lighter high-tech products.

High-tech applications

Rare-earth elements have been called “chemical vitamins,” because as little as 0.2% of these special metals, alloyed with other materials, can affect glass, metal, and electronic products in ways that no other element can. Some are used in night-vision goggles and sunglass lenses, while others assist in producing lasers, screen displays, the world’s strongest magnets, and even ear buds.

In the 1970s, color television was the first
technological invention to explore the optical
properties of rare-earth elements. Scien-
tists found that when materials containing
europium and yttrium were coated onto
television tubes, they would generate a clear,
Other compounds of europium and ter-
bium were combined to create vivid green
and blue colors and a striking white light,
making television as vivid as movies. Com-
binations of these three luminescent colors
make the whole light spectrum (which is dif-
ferent from the pigment spectrum of paints
and crayons) possible. Today, these “technol-
ogy metals” are used in flat-screen televisions
and in the display panels of smartphones and
tablets.

Rare-earth elements are also found in sports equipment. Bicycles and baseball bats, golf clubs, and hockey sticks sometimes take advantage of an alloy made of scandium and aluminum to get more power from less weight. An alloy is a mixture of metals or a mixture of a metal and another element. The scandium-aluminum alloy is made by incorporating nanoparticles—particles that are less than 100 nanometers and contain atoms SHU