Europium

The story of the rare earth elements is a story of ongoing discovery. And europium is a case in point!

In 1803, ceria—which was thought to be a new element—was discovered in ores from a mine in Bastnäs, Sweden. Although ceria did contain the element cerium, it contained other elements, too. In 1839, Swedish chemist Carl Mosander separated lanthanum and didymium from ceria as well.

Mosander thought that didymium was its own element, but this wasn't the case. In fact, didymium is made mostly of two elements, which Austrian chemist Carl Auer von Welsbach separated in the 1880s. These elements became known as neodymium and praseodymium.

But wait! There's more! In addition to neodymium and praseodymium, there were other elements in the didymium yet to be discovered. In 1879, French chemist Paul-Émile Lecoq de Boisbaudran separated samarium from didymium—but the samarium wasn’t pure, either! In 1880, Swiss chemist Jean Charles Galissard de Marignac separated the element gadolinium from samarium. Like a Russian nesting doll, there appeared to be one more metal in the samarium, which French chemist Eugène-Anatole Demarçay at last separated in 1901. He named europium after—you guessed it—Europe. The name was fitting, given how many European scientists it took to find the element!

Europium is a relatively soft metal that is ductile (meaning that it can be stretched without breaking). It is the most reactive of the rare earth elements, which is why it tarnishes quickly in air.

In the early 1960s, it was discovered that europium could be used in television sets to produce a vibrant red color, which caused demand for the element to soar. Europium(II) can also be used in televisions to produce the color blue. Europium is great at absorbing neutrons, so it’s also used in lasers and in nuclear control rods. All told, europium doesn’t have quite as many uses as some other rare earth elements do—but it’s still plenty useful!

Europium is unusual among the rare earth metals for its ability to form divalent compounds. Europium(II) oxide has been researched for potential use in magnetic refrigeration. That’s not a refrigerator with magnets on it; it’s the use of magnets to make things cold!

Europium(II) sulfide has also been researched for use in magnets, as well as in semiconductors. Europium(III) oxide is used in tubes in old-fashioned televisions, while europium-doped yttrium oxysulfide can used in light-emitting diodes (LEDs).

In nature, europium comes in the form of two isotopes. Just under 50% of naturally occurring europium is europium-151, while just over 50% of naturally occurring europium is europium-153. Europium-153 is stable (non-radioactive), while europium-151 is unstable, although the isotope has a very long half-life (of 5 x 10¹⁸ years).

Scientists have produced 35 other europium isotopes, all of which are radioactive. The half-lives of these isotopes range from around 37 years to mere nanoseconds.

Like other rare earth elements, you won’t find europium by itself in nature. Instead, europium is something of a “buddy element” that’s extracted alongside other rare earth elements from ores such as bastnäsite and monazite.

The largest producers of europium, and of most of the rare earth metals, are China, Russia, and Malaysia.