Ytterbium

Ytterbium is a soft, silvery lanthanide named after Ytterby, Sweden. It is used in the most precise atomic clocks ever built, ytterbium optical lattice clocks are so accurate they would not gain or lose one second in 14 billion years, and in specialised fibre lasers.

• Atomic Number7070 protons, 70 electrons
• Atomic Mass173.05 u70× heavier than hydrogen
• State at Room TempSolidSolid
• Density6.90 g/cm³
• Melting / Boiling818.9°C / 1195.8°C
• Discovered1878

What is Ytterbium?

Ytterbium is a lanthanide rare earth metal with 70 protons. Ytterbium optical lattice clocks are currently the most accurate timekeepers ever built, surpassing even caesium atomic clocks. They work by trapping ytterbium atoms in a lattice of laser light and measuring transitions between electronic states at optical frequencies. Also used in stainless steel to improve grain structure and in Yb-doped fibre lasers.

Fact Ytterbium is element 70 in the periodic table, symbol Yb. As a lanthanide, it is part of the group of 15 elements sharing very similar chemistry, formed by the filling of the 4f electron subshell. All lanthanides form stable +3 ions and are found together in rare earth mineral deposits.

Where you find Ytterbium

On Earth

Ytterbium is found alongside other rare earth elements in minerals such as monazite, bastnäsite and xenotime. China produces the vast majority of world supply, with smaller contributions from Australia, the United States, Russia and India. It is never found as a free metal in nature.

• Monazite and bastnäsite. The primary rare earth minerals that contain Ytterbium.
• Ion-adsorption clays. Certain clay deposits in southern China are particularly rich in heavier lanthanides including Ytterbium.

How we use Ytterbium

Ytterbium optical lattice clocks are currently the most accurate timekeepers ever built, surpassing even caesium atomic clocks. They work by trapping ytterbium atoms in a lattice of laser light and measuring transitions between electronic states at optical frequencies. Also used in stainless steel to improve grain structure and in Yb-doped fibre lasers.

Did you know? Ytterbium was one of the last lanthanides to be isolated in pure form. The extraordinary chemical similarity between adjacent lanthanides made separation extraordinarily difficult until ion exchange chromatography was developed in the 1940s.

How it was discovered

Ytterbium was identified and separated from the mixture of rare earth elements found in minerals from Ytterby, Sweden and other locations, through painstaking fractional crystallisation and spectroscopic analysis over many decades in the 19th century.

Deeper dive: ytterbium and rare earth supply chains

The lanthanides, often called rare earth elements, are critically important for clean energy technologies. Neodymium and praseodymium go into the powerful magnets in EV motors and wind turbines. Dysprosium improves those magnets at high temperatures. Lanthanum and cerium go into NiMH batteries, catalysts and glass. Europium and terbium provide red and green in LED phosphors. This means that the global transition to clean energy depends heavily on rare earth elements, and their supply is dominated by China, which produces over 60% of the world's rare earth output. Concerns about supply security have spurred investment in rare earth mining projects in Australia, Canada, the USA and elsewhere.

Moving to 71 protons brings us to the next element on the periodic table.