Yttrium

Category: transition metal Atomic number: 39 Colour: silvery white Melting point: 1,522°C (2,772°F) Boiling point: 3,345°C (6,053°F) First identified: 1828

Ytterby is a village on the Swedish island of Resarö, which is now mostly suburban housing (it is about half an hour by road from Stockholm). However, it used to be the home of the country’s most productive mine, producing feldspar (for porcelain) and quartz. As it happens, it is also the place with the most elements named after it.

In 1787, Carl Axel Arrhenius (a soldier and amateur chemist) found a lump of black mineral that was fairly uninteresting to look at, but unusually heavy. It was later named ‘gadolinite’ (sometimes known as ‘ytterbite’). The Swedish chemist Johan Gadolin (see here) established that 38 per cent of the rock must be a new, unidentified ‘earth’ (meaning that it was an unknown oxide), which proved impossible to reduce by burning with charcoal or other traditional methods.

It was only in 1828 that Friedrich Wöhler managed to rip the pure element out of the oxide, using a more violent reaction with potassium to separate out the oxygen, and producing pure yttrium. (The element has proved to be far more common on the moon than here – lunar astronauts have brought back significant amounts of it in moon rock.) However, as we will see, there were still three more unknown elements hiding in the gadolinite and, astonishingly, three more elements to be discovered as a consequence of these finds (see here).

Yttrium is a soft, silvery metal that has to be handled carefully, usually in nitrogen, as it combusts in air. It can be used to strengthen alloys of aluminium and magnesium, in microwave filters for radar technology, and in LED lighting and lasers. Yttrium oxide is added to glass to make it more resistant to heat and shock – for instance, it is used in bulletproof glass. There is also currently a lot of scientific interest in yttrium barium copper oxide (YBCO). In the 1980s, two American chemists showed that it becomes superconducting (meaning it will conduct electricity with no loss of energy) at the unusually high temperature of 95° above absolute zero (−178ºC). This could, in theory, enable us to build cheaper MRI scanners, as the YBCO could be kept as a superconductor, using liquid nitrogen rather than the more expensive liquid helium, but there are still technical difficulties to be solved in making this a reality.