What is samarium used for?
By RareMetals.net Editorial Team · Updated
Samarium is used mainly in samarium-cobalt (SmCo) permanent magnets, which keep their strength at temperatures up to about 350 °C and resist corrosion. Smaller uses are neutron absorbers in nuclear reactors, a bone-cancer pain medicine (samarium-153), chemical catalysts and reagents, and infrared-absorbing glass.
Main uses of samarium at a glance
| Application | What samarium does | Examples |
|---|---|---|
| Samarium-cobalt magnets | Strong permanent magnets that work up to about 350 °C and resist corrosion | Missile guidance, aircraft and satellite actuators, high-temperature motors and sensors |
| Nuclear reactors | Samarium-149 absorbs neutrons | Control rods and neutron shielding |
| Medicine | Samarium-153 targets bone | Samarium-153 lexidronam for pain from bone metastases |
| Catalysts and chemistry | Samarium(II) iodide is a selective reducing agent | Organic synthesis, dehydration catalysts |
| Glass | Absorbs infrared light | Optical and laser glass |
Samarium-cobalt magnets
SmCo magnets come in two families, SmCo₅ and Sm₂Co₁₇. They are slightly weaker than neodymium magnets at room temperature, but they lose far less strength as they heat up and do not need coatings to resist corrosion. That makes them the standard choice for missile guidance and fin actuators, aircraft and satellite motors, high-speed motors and generators, travelling-wave tubes, and sensors that work in hot environments.
Because these uses are mostly defence and aerospace, samarium supply is treated as a security issue. The US government listed 60 tons of samarium-cobalt alloy as a potential stockpile purchase for fiscal 2025, and China put samarium on its export-licence list in April 2025.
Nuclear reactors
Samarium-149 absorbs neutrons strongly. It builds up in nuclear fuel during operation and is also used in some control and shielding materials.
Medicine
Samarium-153 lexidronam is a radioactive medicine that concentrates in bone and is used to relieve pain from cancers that have spread to the bones.
Chemistry and materials
Samarium(II) iodide is a widely used reagent in organic synthesis. Samarium oxide is a catalyst for some dehydration reactions, samarium-doped ceria is an electrolyte in solid oxide fuel cells, and samarium is added to glass that must absorb infrared light.
Products that contain samarium
- Missile and aircraft actuators
- High-temperature motors and sensors
- Satellite systems
- Nuclear reactor materials
- Bone-pain radiopharmaceuticals
Can samarium be replaced?
NdFeB magnets with dysprosium or terbium can replace samarium-cobalt below about 200 °C. Above that, and where corrosion resistance matters, there is no practical substitute.
Samarium uses FAQ
What is samarium used for in everyday life?
Very little that people handle directly. Most samarium goes into samarium-cobalt magnets in aircraft, defence systems, satellites and industrial equipment.
Are samarium magnets better than neodymium magnets?
Not at room temperature, where neodymium magnets are stronger. Samarium-cobalt magnets are better above about 150-200 °C and in corrosive environments.
Why is samarium strategic?
Samarium-cobalt magnets are hard to replace in high-temperature defence uses, and China produces most separated samarium and has required export licences since April 2025.