rare-earth element

Introduction
Discovery and history
Abundance, occurrence, and reserves
Minerals and ores
- Bastnasite
- Laterite clays
- Monazite
- Loparite
- Xenotime
Electronic structure and ionic radius
Processing ores
Separation chemistry
- Ion exchange
- Solvent extraction
Preparation of the metals
- Calciothermic method
- Electrolytic method
- Preparation of samarium, europium, thulium, and ytterbium: lanthanothermic process
Properties of the metals
- Crystal structures
- Melting points
- Boiling points
- Electrical properties
- Magnetic properties
- Thermal expansion
- Elastic properties
- Mechanical properties
- Chemical properties
Compounds
- Oxides
  - Sesquioxides
  - Higher oxides
  - Lower oxides
  - Ternary and higher-order oxides
- Hydrides
- Halides
- Metallic and complex compounds
  - Permanent magnets
  - Rechargeable batteries
  - Electron guns
  - Microkelvin cooling
  - Magnetostriction
  - Giant magnetocaloric effect
- Complexes
Nuclear properties
Toxicity

References & Edit History Quick Facts & Related Topics

Images

A line graph showing electron probability distributions for gadolinium, with separate curves for 4f, 5s, 5p, 5d, and 6s orbitals. The x-axis shows distance from the nucleus in atomic units and the y-axis shows probability P2(r).

A line graph plots the metallic radius in angstroms versus atomic number for lanthanides and related rare-earth elements, showing a general decrease across the series with notable peaks at europium (Eu) and ytterbium (Yb).

Line graph showing the melting and transformation temperatures of lanthanide and rare-earth elements, with atomic number on the x-axis and temperature in degrees Celsius on the y-axis. Melting points are marked with red circles connected by a solid line, while transformation temperatures use various symbols for different crystal structure changes.

Line graph showing the boiling points of rare-earth elements versus atomic number, with each element labeled along the x-axis and boiling points in degrees Celsius on the y-axis. The plot highlights significant variation in boiling points across the series, including sharp drops for europium and ytterbium.

Diagram showing four types of crystal structures for rare-earth metals, each represented by colored geometric models with labeled axes and atomic positions. The structures include hexagonal close-packed (hcp), face-centered cubic (fcc), double hexagonal close-packed (dhcp), and Sm-type, with examples of elements listed below each structure.

A line graph plots the coefficient of linear thermal expansion for rare-earth elements by atomic number, showing three data series: polycrystalline (yellow triangles), expansion along the c-axis (red circles), and a-axis (blue squares). The x-axis lists elements from scandium to lutetium, and the y-axis shows the coefficient values.

A line graph plots Young's modulus, bulk modulus, and shear modulus in gigapascals for rare-earth elements, with atomic number on the x-axis and modulus values on the y-axis. Each element is labeled along the bottom, and three lines-orange triangles for Young's modulus, red circles for bulk modulus, and blue squares for shear modulus-show how these elastic properties vary across the series, with notable dips for europium and ytterbium.

Graph of free energy of formation (delta Gf degree) for rare-earth elements from scandium to lutetium. Values generally decrease with atomic number, with spikes at europium and ytterbium.

The arrangement of copper, yttrium, oxygen, and barium ions in yttrium barium copper oxide (YBa2Cu3O7), an example of a superconducting ceramic crystal structure.

At a Glance

rare earth metal summary

rare-earth element

chemistry

Also known as: inner transition element, rare-earth metal

Written by

Vitalij K. PecharskyAll

Fact-checked by

Britannica Editors

Last updated

Oct. 18, 2026 •History

rare-earth element, any member of the group of chemical elements consisting of three elements in Group 3 (scandium [Sc], yttrium [Y], and lanthanum [La]) and the first extended row of elements below the main body of the periodic table (cerium [Ce] through lutetium [Lu]). The elements cerium through lutetium are called the lanthanides, but many scientists also, though incorrectly, call those elements rare earths. The rare earths are generally trivalent elements, but a few have...

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