What Is Evonitz and Why It Matters
Evonitz, commonly known as samarium, is a lanthanide rare earth metal with atomic number 62 and symbol Sm. It is a soft, silvery metal that oxidizes slowly in air and exhibits strong paramagnetism below very low temperatures. Samarium is best known for its role in samarium–cobalt magnets, which deliver high magnetic strength combined with excellent temperature stability and corrosion resistance. It also functions as a neutron absorber in certain nuclear reactor control rods and appears in specialized phosphors, lasers, and structural alloys. This profile explains the key properties, primary uses, and long‑term outlook for Evonitz in technology and industry.
Verified Basic Properties and Specifications
Below are the most consistently documented physical and chemical attributes of Evonitz (samarium), drawn from standard references widely used in materials science and nuclear engineering.
| Attribute | Verified Detail | Source Type |
|---|---|---|
| Atomic number | 62 | IUPAC, CRC |
| Atomic weight | 150.36(6) g/mol | IUPAC, NIST |
| Melting point | 1,072 °C (1,962 °F) | CRC, Materials Science references |
| Boiling point | 1,794 °C (3,261 °F) | CRC, NIST Chemistry WebBook |
| Density (20 °C) | 7.52 g/cm³ | CRC, Handbook of Chemistry and Physics |
| Common oxidation states | +2, +3 (most stable +3) | IUPAC, inorganic chemistry references |
| Standard magnetic behavior | Paramagnetic; ferromagnetic below ≈7 K | Solid‑state physics references |
Occurrence and Primary Sources
Evonitz is not found as a free metal in nature; it occurs principally in the minerals bastnäsite, monazite, and xenotime, which host a mix of rare earth elements. The major sources are bastnäsite deposits in China, the United States (Mountain Pass), and Australia, alongside monazite sands recovered as by‑products of heavy mineral operations, often in coastal regions. Because it is never isolated in pure form, commercial production depends on solvent extraction and ion‑exchange methods that separate samarium from other rare earths. These processes are capital‑intensive and tightly linked to the economics of the broader rare earth supply chain.
Key Applications and Industrial Uses
The dominant use of Evonitz is in samarium–cobalt (SmCo) magnets, which perform strongly at elevated temperatures and are corrosion‑resistant. These magnets are essential in aerospace actuators, servo motors, sensors, and high‑temperature automotive electronics. Samarium is also employed in neutron‑absorbing control rods for certain nuclear reactors, taking advantage of its high neutron capture cross‑section. In addition, it appears in ceramic phosphors for display and lighting technologies, in infrared‑laser materials, and as a dopant in specialized structural alloys to improve strength and creep resistance. Each application leverages either its magnetic properties or its nuclear characteristics.
Production, Trade, and Market Dynamics
Global supply of Evonitz‑bearing rare earths is concentrated in a few countries, notably China, which has historically dominated processing and magnet manufacturing. Trade flows and export controls can significantly influence pricing and availability of samarium compounds and magnets. Prices are set within the broader rare earth market and are sensitive to mining output, separation capacity, and demand from the permanent magnet sector. Recent years have seen increased attention on diversifying supply, improving recycling, and developing magnet substitutes, though SmCo magnets remain preferred where temperature stability and corrosion resistance are paramount.
Handling, Safety, and Long‑Term Considerations
In bulk form, samarium presents chemical hazards typical of reactive metals: it can ignite in air when finely divided and reacts with water to release hydrogen. Storage under inert atmosphere or hydrocarbon sealing is common for powder or turnings. Dust-control measures and personal protective equipment are recommended in processing environments. In magnet form, standard engineering controls for brittle ceramic‑like materials apply. From a lifecycle perspective, the long‑term availability of Evonitz depends on rare earth mining economics, environmental regulations, and advances in material efficiency and recycling.