Samarium

Samarium is a silvery lanthanide best known for samarium-cobalt magnets, high-performance permanent magnets that were the strongest available before neodymium-iron-boron was developed. They remain preferred in applications requiring stability at high temperatures.

• Atomic Number6262 protons, 62 electrons
• Atomic Mass150.4 u62× heavier than hydrogen
• State at Room TempSolidSolid
• Density7.52 g/cm³
• Melting / Boiling1073.8°C / 1793.8°C
• Discovered1879

What is Samarium?

Samarium is a lanthanide rare earth metal with 62 protons. Sm₂Co₁₇ and SmCo₅ alloy magnets retain their magnetic properties up to 300°C, far above the Curie temperature of NdFeB magnets. Samarium-153 is used in cancer pain treatment.

Fact Samarium is element 62 in the periodic table, symbol Sm. 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 Samarium

On Earth

Samarium 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 Samarium.
• Ion-adsorption clays. Certain clay deposits in southern China are particularly rich in heavier lanthanides including Samarium.

How we use Samarium

Sm₂Co₁₇ and SmCo₅ alloy magnets retain their magnetic properties up to 300°C, far above the Curie temperature of NdFeB magnets. Samarium-153 is used in cancer pain treatment.

Did you know? Samarium 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

Samarium 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: samarium 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 63 protons brings us to the next element on the periodic table.