Erbium

Look at the periodic table, and you’ll notice that some of the elements have awfully similar names—ytterbium, yttrium, terbium, and erbium. That’s because these elements were all discovered in minerals found near the village of Ytterby, Sweden. If you have a hard time keeping these elements straight, you’re not alone!

These elements all have similar properties, so discovering many of them was a long and sometimes confusing process. That was certainly the case with erbium, which Swedish chemist Carl Gustaf Mosander discovered in a piece of gadolinite from Ytterby. Mosander thought that this chemical sample was an oxide (a compound of oxygen and some other element) called yttria. From the sample, he also separated out two other oxides, which he called “erbia” and “terbia.”

It turned out that giving these oxides such similar names wasn’t the best idea. Not long after Mosander’s discoveries, another chemist confused erbia with terbia. That mix-up caused scientists problems for more than two decades! That confusion wouldn't be cleared up until the oxides, and the elements erbium and terbium that they contained, were finally renamed.

In addition to erbium and terbium, the gadolinite that Mosander analyzed ended up containing five other new elements—ytterbium, scandium, thulium, holmium, and gadolinium. Now just try to keep the names straight!

Like other rare earth metals, in metallic form, erbium is soft, malleable (meaning capable of being shaped), and silvery white. In compounds such as erbium oxide, erbium had a distinct pink color. Erbium has very sharp and specific absorption bands, which means it absorbs and emits light at very precise wavelengths. This makes it especially useful in technologies like lasers and fiber optics (think high-speed internet and medical equipment), where accurately controlling light is important.

Erbium is often used in lasers, especially in medical applications. Dentists use erbium lasers to clean teeth, dermatologists use erbium lasers to make skin look younger, and surgeons use erbium lasers to conduct laser surgery.

Erbium is also commonly used in fiber-optic cables. By incorporating erbium into fiber optics at regular intervals, it’s possible to amplify the laser signals that travel along the cables’ length. You might have erbium to thank (or blame) for making it possible to read this article!

Erbium oxide is the form of erbium first obtained by Carl Mosander in the 1840s. Erbium oxide has a pink-lemonade color, which is why it’s sometimes used in cheap jewelry or sunglasses.

Erbium tetraboride, which is hard and has a high melting point, has many applications, so it’s used in applications that range from semiconductors to the nozzles of rocket engines. Erbium fluoride is used in fiber optics and for other optical applications.

Naturally occurring erbium comes in six stable (non-radioactive) isotopes—erbium-162, erbium-164, erbium-166, erbium-168, and erbium-170. About one third of natural erbium is erbium-166, the most common isotope, followed by erbium-168 (which makes up about 27% of naturally occurring erbium).

Scientists have made around 30 radioactive erbium isotopes. Their half-lives range from around 9 days to several seconds.

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