Erbium
Erbium is a chemical element in the lanthanide series, with symbol Er and atomic number 68. A silvery-white solid metal when artificially isolated, natural erbium is always found in chemical combination with other elements on Earth. As such, it is a rare earth element which is associated with several other rare elements in the mineral gadolinite from Ytterby in Sweden, where yttrium, ytterbium, and terbium were discovered.
Identity
- Atomic mass
- 167.259 u
- Category
- Lanthanides
- Group
- 3
- Period
- 6
- Block
- f
- Oxidation States
- +3
- Phase (25 °C)
- Solid
- Appearance
- silvery white
Electronic Structure
- Electron configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f12
- Short configuration
- [Xe] 4f12 6s2
- Electrons per shell
- 2, 8, 18, 30, 8, 2
- Electronegativity (Pauling)
- 1.24
- Electron affinity
- 30.1 kJ/mol
- 1st ionization energy
- 589 kJ/mol
- Ionization energies
- 589 · 1150 · 2194 · 4120 kJ/mol
Physical properties
- Melting point
- 1528.8 °C (1802 K)
- Boiling point
- 2867.8 °C (3141 K)
- Density
- 9.066 g/cm³
- Molar heat capacity
- 28.1 J/(mol·K)
Chemical behavior of erbium
Erbium has twelve outer electrons ([Xe] 4f¹² 6s²) and almost always acts as +3, with low electronegativity (1.24). It forms highly ionic bonds and characteristic pink salts. It is soft, malleable and relatively stable in air. Its Er³⁺ ions absorb and emit in the infrared with great efficiency: they amplify the light of the Internet and generate the most precise surgical laser.
Reactivity
4 Er + 3 O₂ → 2 Er₂O₃
In dry air it tarnishes slowly with a pinkish oxide; in moist air the corrosion progresses. When heated, it burns to the oxide.
2 Er + 6 H₂O → 2 Er(OH)₃ + 3 H₂
It reacts slowly when cold and vigorously when hot, releasing hydrogen. The doped fibers that contain it, by contrast, are insoluble and stable.
2 Er + 6 HCl → 2 ErCl₃ + 3 H₂
It dissolves in acids giving pink erbium(III) salts. The chloride is the raw material for EDFA fibers and Er:YAG garnets.
Er + 3 F₂ → 2 ErF₃
With fluorine it gives the fluoride, a precursor of laser crystals and fluorinated glasses for mid-infrared optical fiber.
Notable compounds
| Compound | Formula | Use or importance |
|---|---|---|
| Erbium oxide | Er₂O₃ | EDFA fibers and pink glasses |
| Er:YAG garnet | Er:Y₃Al₅O₁₂ | Dental and dermatological laser |
| Erbium-doped fiber | SiO₂:Er | Internet amplifiers |
| Erbium chloride | ErCl₃ | Production of the metal and fibers |
| Erbium fluoride | ErF₃ | Laser crystals and IR optics |
Electron shell distribution
View in the atom builderIsotopes
Natural erbium mixes six stable isotopes: 162Er (~0.14%), 164Er (~1.6%), 166Er (~33.6%), 167Er (~22.95%), 168Er (~26.8%) and 170Er (~14.9%), all with 68 protons. 167Er, with nuclear spin, is used in resonance and clocks; 170Er is a target for producing medical and industrial thulium-170.
Occurrence and production
It appears at about 3.5 ppm in monazite, bastnasite and xenotime alongside holmium and thulium. The main deposits are in China, the United States and Australia. It is obtained by acid dissolution, solvent extraction and ion exchange, and the metal by electrolysis or reduction with calcium.
History and origin of the name
Carl Gustaf Mosander caught a glimpse of it in 1843 in yttria and Per Teodor Cleve confirmed it in 1879, separating erbium from terbium and ytterbia. They named it erbium, after Ytterby, the Swedish village that gave its name to four elements. For a century it was a pink pigment until optical fibers made it the soul of the Internet.
Applications and relevance of erbium
Uses of the element
As a dopant in silica fibers it amplifies the Internet signal in the 1,550 nm band without converting it to electricity: every undersea repeater carries erbium. It also dopes alloys and magnetic concentrators for cryogenics.
Uses of its compounds
The Er:YAG garnet (2,940 nm) vaporizes skin and enamel with micrometric precision in dermatology and dentistry. The oxide tints glasses, gemstones and protective glasses pink; the fluoride forms mid-infrared lasers.
Health, safety and environment
Biological role
It has no biological function and is considered of low toxicity. The fibers and glasses that contain it are insoluble and do not release erbium; in medicine the laser light acts, not the free element.
Safety
Metallic powder requires control as combustible dust, with extraction and no flames. Er:YAG lasers require specific glasses and marked enclosures; the risk is optical, not chemical.
Environment
Its low grade means moving much rock per kilo, with reagent consumption. In return, every gram in amplifiers avoids electric repeaters and saves network energy for decades. Fiber and garnet recycling is starting to recover erbium.
Frequently asked questions about Erbium
Why is erbium important for the Internet and telecommunications?
Erbium is essential in the erbium-doped fiber optical amplifiers, known as EDFA. These devices amplify the light signals directly inside the cable, without converting them into electrical signals. Thanks to this, data can travel long distances —including undersea cables— with less loss. A good part of the Internet infrastructure depends, indirectly, on this element.
What is erbium used for in medicine and dentistry?
Erbium is the active element of Er:YAG lasers, which emit infrared light that is strongly absorbed by the water in the tissues. That absorption allows precise ablation with limited thermal penetration. It is used in dermatology for superficial skin renewal treatments and tattoo removal, and in dentistry for procedures on enamel, dentin and periodontal tissues.
Why does erbium give a pink color to some glasses?
When erbium is added to glass, its ions absorb certain wavelengths and transmit others, producing a pink or rosy tone. This property is taken advantage of in sunglasses, synthetic gemstones and decorative glasses. It is also used in glasses that absorb infrared, including protective glasses for welders and metal workers, where it helps filter non-visible radiation.
What is the difference between erbium and holmium lasers?
Erbium lasers, such as Er:YAG, emit close to 2,940 nanometers and are strongly absorbed by water, which makes them suitable for superficial treatments of skin and dental tissues. Holmium lasers, such as Ho:YAG, emit around 2,100 nanometers and penetrate somewhat more, so they are used in urology and endoscopic surgery. Both take advantage of absorption by water, but with different depth and clinical applications.
Why does erbium amplify light in optical fibers?
Erbium ions can absorb energy from a pumping source and release it afterward as light in the band close to 1,550 nanometers, where standard optical fiber has very low losses. By doping the fiber with erbium, the signal traveling through the cable is reinforced as it advances. This process allows information to be transmitted over long distances with greater efficiency and fewer electric repeaters.
Is erbium dangerous?
Erbium is considered of low toxicity and no essential biological function is known in humans. The pure metal oxidizes slowly in air and can be attacked by water, so its industrial handling requires precautions. The practical risks are associated above all with powders, chemical compounds or laser equipment, not with final products such as optical cables, glasses or medical devices.
Where does erbium come from?
Erbium is found mainly in rare-earth minerals such as monazite and bastnasite, together with other lanthanides. After processing of the ore, it is separated by ion exchange and solvent extraction, techniques that are necessary because these elements share very similar chemical properties. It can then be obtained as an oxide, salt or metal for applications in optical fibers, lasers, alloys and special glasses.
Main sources consulted: PubChem, Royal Society of Chemistry, NIST, IUPAC. Last revision: November 2026.