Hafnium

In 1911, French chemist Georges Urbain claimed to have discovered element 72, which he called “celtium.” Although Urbain was right about finding a new element, his descriptions of the element were mostly wrong, so he didn’t truly “discover” the element. In science, it’s important to get the details right!

It wasn’t until 1923 that George Charles de Hevesy and Dirk Coster separated hafnium from zirconium at the University of Copenhagen, officially discovering the element. The two scientists dubbed element 72 “hafnium,” after “Hafnia,” the Latin name for Copenhagen.

Hafnium is a silvery metal that is ductile, meaning it can be stretched without breaking. It’s also resistant to corrosion and acids. Hafnium and zirconium are a lot alike. However, hafnium is denser and a lot better at absorbing neutrons than zirconium is.

Because hafnium resists corrosion and is great at absorbing neutrons, it’s often used in nuclear reactors. Hafnium also gets used in gas-filled and incandescent lamps. It’s also useful as a semiconductor, which can be used in computers. When alloyed with other metals, hafnium metals can be made into spacecraft components and other useful objects.

Hafnium oxide gets used in semiconductors, which are important in electronics. Hafnium carbide has the highest melting point—more than 3900 °C—among known compounds, but this compound is too expensive to be very useful. At high temperatures, hafnium reacts with carbon, boron, nitrogen, oxygen, silicon, and sulfur.

More than 40 hafnium isotopes have been observed, but only five of those isotopes (hafnium-176, -177, -178, -179, and -180) are stable (non-radioactive).

Most hafnium comes from zirconium ores, which are usually about 5% hafnium. Hafnium and zirconium are quite difficult to separate from other elements. Splitting them from each other can be a real headache, too!