Samarium is a hard, silver metal that oxidizes in air to form a yellow-gray powder on the surface of the metal. It is a chemical element with the atomic number 62 and is represented by the chemical symbol Sm. Due to its reactiveness it is never found in its free form in nature, but it can be found in a number of minerals. The most important minerals as a commercial source of the element are monazite and bastnaesite (bastnäsite). It is known as a rare earth element, but it is actually the 40th most common element in the crust of the Earth (more common than tin). The largest reserves of this element are believed to be found in China, the United States, India, Brazil, Australia and Sri Lanka. About 700 metric tons is produced each year for a number of different applications.
Uses of samarium
- An important application of samarium is in the production of samarium-cobalt magnets. These are second only to neodymium magnets in terms of permanent magnetization, but have a higher level of resistance to losing their magnetization due to their stability at high temperatures. These magnets have many uses and are found in small electric motors, headphones, and musical instruments.
- Samarium compounds are also very important in the chemical industry. They are used to decompose plastics, dechlorinate pollutants, dehydrate and dehydrogenate ethanol along with many other uses. The samarium compound samarium iodide is an important reducing and coupling agent in organic synthesis.
- Samarium is added to glass and ceramics to increase the ability to absorb infrared light.
- It is a small part of an alloy of rare earth elements known as mischmetal. This is used as an ignition device for lighters and flints, and is also used in certain types of torches.
- The radioactive isotope samarium-153 is used to kill cancer cells in certain types of cancer (mostly lung, prostate and breast cancer). Another isotope, samarium-149, is used in the control rods of nuclear reactors. By analysing samarium and neodymium isotopes scientists can determine the age of rocks and meteorites (this is called samarium-neodymium dating).
- Samarium is also used in certain types of lasers.