Neodymium

The mid-1800s was a period of intense activity in the search for new elements. This was especially the case for scientists working with the elements that we now call the lanthanides, or rare earth metals. But the process of discovering these elements was challenging because the rare earth metals all behave so similarly! These similarities made it hard for researchers to split the elements apart, and to tell if they’d found a new element, or two, or even more!

Identifying the elements got a lot easier after 1859, when Robert Bunsen and Gustav Kirchhoff invented the spectroscope. Bunsen and Kirchhoff figured out that by burning a substance and examining the light produced in the process (like a colorful fingerprint), it was possible to figure out what the substance was made of.

Back in 1841, Swedish chemist Carl Mosander had found what he thought to be two new elements in a sample of the mineral cerite. He called these two supposed elements “lanthanum” and “didymium.” However, in 1885, one of Robert Bunsen’s students—Austrian chemist Carl Auer von Welsbach— succeeded in splitting up didymium into two elements. He then used spectroscopy to prove that these elements were in fact distinct, and he named the elements neodidymium (meaning “new didymium”) and praseodidymium (“green didymium”). The name “neodidymium” was then modified to “neodymium,” which is what we call the element today.

Like other rare earth metals, neodymium looks like silver. However, neodymium is more reactive than other rare earth elements, which is why it tarnishes quickly in air. Neodymium is ductile (meaning it can be stretched without breaking) and malleable (meaning that it can be hammered or shaped without breaking).

Neodymium often gets used in magnets, and not just the kind that holds receipts to refrigerators. Neodymium magnets are used in electric or hybrid cars or electric generators and wind turbines, in computer hard drives, cell phones, and more.

Neodymium is often used in lasers, especially lasers that operate at high temperatures. In manufacturing, these lasers can be used for engraving or etching, or in medicine—for example, to remove skin cancers. Mixed with its sister element praseodymium, neodymium is often used in glasses designed to protect the eyes of welders or craftspeople, or of people in tanning beds.

Compounds of neodymium, iron, and boron can be made into powerful magnets, and up to 70 percent of neodymium is used in this way. Neodymium acetate can be mixed into the kind of glass that’s used in welding goggles. Neodymium can make a compound with yttrium and aluminum to form yttrium aluminum garnet, which is used in lasers. Neodymium oxide can be used in glass, too, but for more decorative purposes: in daylight, this glass appears purple, but under fluorescent lighting the glass will look blue. It's not magic, it’s science!

In nature, you’ll find neodymium in five stable (non-radioactive), isotopes: neodymium-142, neodymium-143, neodymium-145, neodymium-146, and neodymium-148. Neodymium-142 is the most common: about 27% of neodymium is in this form.

Naturally occurring neodymium also comes in two radioactive isotopes, although both have very long half-lives. Neodymium-144 has a half-life of 2.29×10¹⁵ years, while neodymium-150 has an even longer half-life, of 6.7×1018 years. Scientists have made 31 other neodymium radioisotopes that have half-lives ranging from around 11 days to seconds or less.

Like other rare-earth elements, most neodymium comes from monazite and bastnäsite ores. China is the top producer of these ores, so it’s the top producer of neodymium, too. Russia and Malaysia also produce neodymium.