Samarium

Samarium is one of the 17 rare earth elements. These elements have strikingly similar qualities, and as a result they took a long time to discover!

In 1803, the element cerium was discovered. Although it was thought that cerium might contain other elements as well, researchers were at a loss for a way to separate and characterize these elements.

In 1839, Swedish chemist Carl Gustaf Mosander found lanthanum and didymium, which he thought to be distinct elements, in cerium. However, other researchers came to suspect that this didymium wasn’t a pure element and suspected it was actually two or more distinct elements.

In 1879, French chemist Paul-Émile Lecoq de Boisbaudran separated a sample of didymium from the mineral samarskite (which had been named after Russian mining engineer Vasili Yevgrafovich Samarsky-Bykhovets). Lecoq de Boisbaudran then separated the hydroxide of a new element from the didymium, which he named samarium, after the mineral in which it was found.

Samarium is a silvery metal that looks a lot like the other rare-earth elements. It is the second most abundant rare-earth elements. It is fairly stable in air, although it will oxidize slowly. Mixed with water, samarium turns into samarium hydroxide.

Alloyed with cobalt, samarium can be used in magnets that are incredibly powerful—up to 10 thousand times more powerful than iron magnets, in fact. These magnets are used in everything from motors to headphones (although neodymium magnets are more common nowadays).

Calcium chloride crystals with samarium mixed into them can be used in lasers. Hollywood uses samarium in lights that help illuminate movie sets. It’s not just genetics—samarium is what makes movie stars look good!

Because samarium is good at absorbing neutrons, it’s sometimes used in nuclear reactors, too. Samarium is also used as a catalyst (which helps make chemical reactions occur).

Samarium oxide is used in ceramics and glassmaking. Samarium iodide (SmI₂) is used to synthesize artificial substances that resemble natural ones. Few of the lanthanides form a monoxide, but samarium does.

Samarium(II) sulfide is an especially unusual compound: these black crystals function like semiconductors, but if you scratch them or expose them to high pressures, they turn a yellowish-gold color and conduct electricity like a metal!

In nature, you’ll find samarium in five stable (non-radioactive) isotopes: samarium-144, samarium-149, samarium-150, samarium-152, and samarium-154. Naturally occurring samarium also comes in two radioisotopes, samarium-147 and samarium-148, which have very long half-lives (of 1.06 x 10¹¹ years and 7 x 10¹⁵ years, respectively). Samarium-152 is the most abundant isotope: about 27% of naturally occurring samarium is in this form.

Altogether, researchers have characterized some 38 isotopes of samarium. The longest-lived synthetic, or artificial, samarium isotope has a half-life of 94.6 years. The shortest-lived have half-lives of mere microseconds.

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