Praseodymium

Praseodymium is one of those elements that just can’t stand to be alone. That’s why you’ll only ever find praseodymium in nature alongside other rare earth metals, such as cerium, lanthanum, or praseodymium’s sister element, neodymium. In fact, praseodymium and neodymium are so similar that for decades, scientists couldn’t tell them apart!

In 1841, Swedish chemist Carl Mosander 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, Austrian chemist Carl Auer von Welsbach succeeded in splitting didymium up into two elements.

Von Welsbach was a student of German chemist Robert Bunsen, who, in addition to inventing the Bunsen burner, helped develop the technique of spectroscopy (which involves burning a substance and examining the light emitted in the process to determine what the substance was made of). Using spectroscopy, von Welsbach was able to prove that the two elements he’d separated out from didymium were indeed distinct. He named the elements neodidymium (meaning “new didymium”) and praseodidymium (meaning “green didymium,” after the element’s oxide’s color). The name “praseodidymium” was then modified to “praseodymium,” which is what we call the element today.

Like other rare earth metals, praseodymium looks like silver. Praseodymium is moderately soft, ductile (meaning it can be stretched without breaking), and malleable (meaning that it can be hammered or shaped without breaking). Because rare-earth metals share many similar properties, praseodymium can often be substituted seamlessly in most applications involving rare-earth metals.

Praseodymium is reactive enough that it needs to be stored in mineral oil or sealed in plastic, or else it will form a greenish layer of oxide.

Praseodymium can be used in a ceramic glaze called Praseodymium Yellow, which is remarkably bright in color—think of banana-flavored Laffy Taffy! Praseodymium can also be mixed into zirconia to give inexpensive jewelry a greenish tint.

Praseodymium is used in praseodymium-neodymium magnets, which are in everything from electric or hybrid cars and wind turbines to computer hard drives, cell phones, and more. Alloyed with magnesium, praseodymium can help create very strong metals that are used in things like aircraft engines. Mixed with its sister element neodymium, praseodymium is often used in glasses designed to protect the eyes of welders or craftspeople, or of people in tanning beds.

Praseodymium-nickel metals can be used in magnetic refrigeration. In fact, these magnets have been used by scientists to approach absolute zero—the coldest temperature imaginable!

Other praseodymium compounds, such as praseodymium(III) oxalate, are used to give ceramics, glass, and other substances a yellow color. Mixed with other elements, praseodymium oxide can help catalyze oxidation (when an element loses electrons during a chemical reaction).

Praseodymium only has one naturally occurring isotope, praseodymium-141, which is stable (non-radioactive). Scientists have produced around 40 praseodymium radioisotopes. Praseodymium-143 has a half-life of nearly 14 days, while all the other isotopes have half-lives of less than one day, and most have half-lives of less than one minute.

Like other rare earth metals, most praseodymium comes from monazite and bastnäsite ores. China is the top producer of these ores, so it’s the top producer of praseodymium, too. Russia and Malaysia also produce praseodymium. Praseodymium also occurs as a product of fissioning uranium.