This metal is named after a person. Vasili Samarsky-Bykhovets was a Russian mining engineer. In 1839, he handed an unusual mineral to chemists. Forty years later, they found a new element inside and named it samarium. He never knew.
Samarium is a silvery, soft metal from the lanthanide family. It slowly tarnishes in air. But inside ultra-powerful magnets, it shines. Samarium-cobalt magnets withstand 350 °C without losing strength. That is why they go into jet engines and spacecraft.
Samarium-cobalt magnets are this element's main superpower. They are weaker than neodymium magnets, but they work in extreme heat where neodymium fails. Samarium also plays a role in nuclear medicine. The isotope Sm-153 targets cancer cells in bones while sparing healthy tissue. And in chemistry labs, samarium iodide SmI₂ is a legendary reagent for building complex molecules.
Samarium powder is pyrophoric — it ignites spontaneously in air at 150 °C. Bulk metal is safer but slowly oxidizes in moist air. Samarium iodide SmI₂ is instantly destroyed by oxygen and water, so it requires sealed gloveboxes. Radioactive Sm-153 needs lead shielding. Overall, samarium has low toxicity, but inhaling its dust irritates the lungs.
Samarium is the only element named after a real person. Vasili Samarsky-Bykhovets was a mining engineer from Russia. He never even knew the mineral samarskite hid a new element inside.
Samarium-cobalt magnets work at 350 °C. Neodymium magnets fail at that temperature. That is why SmCo goes into jet engines and gas turbines.
Isotope Sm-149 absorbs neutrons better than anything else. Its capture cross-section is 40,900 barns. It acts like a giant neutron trap inside nuclear reactors.
Isotope Sm-153 fights bone cancer. It emits beta particles that destroy tumor cells within 2-3 mm. Healthy tissue around it stays mostly unharmed.
Samarium iodide SmI₂ has been a star of organic chemistry since 1977. It builds complex molecules with surgical precision. Chemists call it the 'magic reagent'.
Isotope Sm-147 decays with a half-life of 106 billion years. That is 8 times the age of the universe. Geologists use it to date the oldest rocks on Earth.
| Isotope | Mass (u) | Abundance | Half-life | Decay |
|---|---|---|---|---|
144Sm | 143.911999 | 3.07% | stable | — |
147Sm☢ | 146.914898 | 14.99% | 1.06×10¹¹ years | α |
148Sm☢ | 147.914823 | 11.24% | 7×10¹⁵ years | α |
149Sm | 148.917185 | 13.82% | stable | — |
150Sm | 149.917275 | 7.38% | stable | — |
152Sm | 151.919732 | 26.75% | stable | — |
154Sm | 153.922209 | 22.75% | stable | — |
Spectroscopic analysis of samarskite