Ytterbium Yb

Discovery

In 1878 the Swiss chemist Jean Charles Galissard de Marignac heated erbium nitrate and separated a white oxide with different properties, which he called ytterbia.

Ytterbia was not pure either. In 1907 Georges Urbain in France and Carl Auer von Welsbach in Austria independently split it and found another element, lutetium; the remainder is today's ytterbium. Reasonably pure ytterbium metal was not produced until the 1950s.

Origin of the name

The name comes from the Swedish village of Ytterby, which also inspired yttrium, terbium and erbium. Ytterbium and yttrium are easy to confuse, but they are different elements with different chemistry.

Main uses

• Optical lattice clocks: ytterbium atoms held in a lattice of laser light tick at an optical frequency so stably that such clocks would drift by less than a second over billions of years; they are candidates for a future redefinition of the second.
• Fibre lasers: ytterbium-doped fibre lasers emit high-power light near 1 micrometre very efficiently and are widely used for cutting and welding metal and for metal 3D printing.
• Stress gauges: its electrical resistance changes with pressure, so it is used in gauges that record shock waves from explosions and earthquakes.
• Radiation sources: ytterbium-169 is used as a portable gamma source for radiography.

Isotopes

Natural ytterbium is made of seven stable isotopes, with ytterbium-174 the most abundant at roughly a third. Atomic clocks typically use ytterbium-171 or ytterbium-174. Radioactive ytterbium-169 has a half-life of about 32 days.

In everyday life

You are unlikely to handle ytterbium, but the laser that cut the steel in your car or machined parts of your phone may well have been an ytterbium fibre laser, and the world's official time could one day be kept by ytterbium clocks. Its compounds can irritate the skin and eyes and the metal powder is flammable, but overall toxicity is considered low.