Rare-earth elements
Rare-earth elements are a group of chemically related metallic elements known for distinctive magnetic optical catalytic and electronic properties. The group is generally associated with the fifteen lanthanides while yttrium is also commonly included because it behaves similarly in many mineral and chemical systems.
Despite the name many rare-earth elements are not exceptionally rare in Earth's crust. Their importance comes from the difficulty of finding economically concentrated deposits and from the technical complexity of separating closely related elements from one another.
Overview
Rare-earth elements frequently occur together in mineral ores. Their chemistry is similar enough that refining and purification can require several processing stages. Once separated these elements can provide unusual performance in high-strength magnets specialized optical systems catalysts lighting phosphors electronic components and advanced materials.
Selected elements
| Element | Symbol | Atomic number | Summary | Common applications |
|---|---|---|---|---|
| Lanthanum | La | 57 | A soft reactive rare-earth metal used in specialized industrial materials. | Battery materials optical glass camera lenses and petroleum-refining catalysts. |
| Cerium | Ce | 58 | One of the more abundant rare-earth elements and widely used in industrial chemistry. | Catalytic converters glass polishing ceramics and specialty alloys. |
| Neodymium | Nd | 60 | Well known for its role in high-performance permanent magnets. | Electric motors hard drives audio equipment lasers and strong permanent magnets. |
| Europium | Eu | 63 | Valued for strong luminescent properties in display technologies. | Phosphors fluorescent lighting displays and specialized optical materials. |
| Terbium | Tb | 65 | A rare-earth metal with useful luminescent and magnetic characteristics. | Green phosphors fluorescent lamps lasers and electronic materials. |
| Dysprosium | Dy | 66 | Useful where magnetic materials must perform at elevated temperatures. | Permanent magnets data storage devices lasers and selected nuclear technologies. |
| Erbium | Er | 68 | Notable for optical behavior used in communication technologies. | Fiber optics optical amplifiers lasers and specialty glass. |
| Yttrium | Y | 39 | Chemically similar to the lanthanides and commonly grouped with rare-earth elements. | Phosphors ceramics lasers electronics and advanced material systems. |
Applications
Neodymium praseodymium and dysprosium are associated with high-performance magnetic materials used in motors generators and electronic equipment.
Cerium and lanthanum compounds are used in catalytic systems for automotive emissions control and petroleum refining.
Rare-earth compounds are used for polishing optical performance specialty glass color control and precision lenses.
Europium terbium and yttrium compounds are associated with phosphors and light-emitting materials.
Rare-earth materials contribute to data storage communication components sensors lasers and other specialized systems.
Selected rare-earth elements are incorporated into ceramics alloys energy systems and precision industrial materials.
Characteristics
Closely related chemistry
Rare-earth elements can be difficult to separate because many of them have similar chemical properties and are frequently present together in the same mineral deposits.
Specialized performance
Their magnetic optical catalytic and electronic properties can be difficult to reproduce with substitute materials in certain high-performance applications.
Broad industrial value
Uses range from long-established industries such as glass polishing and petroleum refining to advanced magnets electronics fiber optics display materials and precision technology.