Erbium

LANTHANOID · GROUP None · PERIOD 6
68
Er
Erbium
167.26

Atomic Data

Atomic Number68
SymbolEr
Atomic Weight167.26 u
Density (STP)9.066 g/cm³
Melting Point1528.85 °C (1802 K)
Boiling Point2867.85 °C (3141 K)
Electronegativity1.24 (Pauling)
Electron Config.1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f12 5s2 5p6 6s2
Oxidation States+3
Phase at STPSolid
CategoryLanthanoid
Period / Group6 / None
CAS Number7440-52-0

Electron Configuration

[Xe] 4f12 6s2

Shell n Subshell Electrons Cumulative
K11s22
L22s24
L22p610
M33s212
M33p618
M33d1028
N44s230
N44p636
N44d1046
N44f1258
O55s260
O55p666
P66s268
Total 68 68

Isotopes of Erbium

Erbium has six naturally occurring stable isotopes. The most abundant is ¹⁶⁶Er, comprising 33.61% of all naturally occurring Erbium.

Isotope Symbol Protons Neutrons Abundance Stability
Erbium-162¹⁶²Er68940.14Stable
Erbium-164¹⁶⁴Er68961.61Stable
Erbium-166¹⁶⁶Er689833.61Stable
Erbium-167¹⁶⁷Er689922.93Stable
Erbium-168¹⁶⁸Er6810026.78Stable
Erbium-170¹⁷⁰Er6810214.93Stable

Abundance & Occurrence

Erbium is present in Earth's crust at approximately 3.5 ppm by mass and at approximately 0.1 ppm by mass throughout the universe.

Earth's Crust (ppm by mass)

Erbium
3.5 ppm
Silicon (ref.)
277,000 ppm
Oxygen (ref.)
461,000 ppm

Universe (ppm by mass)

Erbium
0.1 ppm
Helium (ref.)
230,000 ppm
Hydrogen (ref.)
739,000 ppm

Discovery & History

1843
Carl Gustaf Mosander: Mosander discovered erbium: along with terbium: by separating the rose-coloured oxide fraction from yttria; the two names were subsequently swapped by later chemists, so Mosander's original 'erbium' became terbium and vice versa.
1879
Per Teodor Cleve: Cleve purified erbium further and correctly delineated it from holmium and thulium, establishing its spectral identity and providing an accurate atomic weight.
1980s
Telecommunications industry: Erbium-doped fibre amplifiers (EDFAs) were developed in the mid-1980s; erbium's emission at 1.55 µm exactly matches the minimum-loss window of silica optical fibre, revolutionising long-distance telecommunications.

Read more about the discovery of the periodic table of elements →

Safety & Handling

  • Dust inhalation: Erbium metal dust and erbium oxide are respiratory irritants; use ventilation and respiratory protection when grinding, machining, or handling fine erbium powders.
  • Er:YAG laser hazard: Erbium-YAG lasers (2.94 µm) are strongly absorbed by water and hydroxyapatite; they are used in dentistry and surgery and cause severe eye and tissue injuries without appropriate laser safety controls and eyewear.
  • Fire hazard: Erbium metal powder is flammable; metal fires require Class D extinguishing agents.
  • General toxicity: Erbium has low acute systemic toxicity; it is not known to be carcinogenic or a reproductive toxicant in standard occupational exposure scenarios.

Real-World Uses

  • Erbium-doped fibre amplifiers (EDFA): Er³-doped silica fibre amplifiers are the backbone of long-haul optical fibre communications; they amplify signals at 1530–1565 nm directly in the optical domain, enabling transoceanic internet cables without electrical regeneration at every repeater.
  • Er:YAG lasers for dermatology and dentistry: The erbium:YAG laser (2940 nm) coincides with the absorption peak of water and hydroxyapatite; it ablates tissue and tooth enamel with minimal collateral damage, used in skin resurfacing, scar treatment, and cavity preparation.
  • Nuclear reactor control: Erbium oxide is used as a burnable absorber in some pressurised water reactor fuel rods, compensating for excess reactivity at the beginning of fuel life and gradually depleting as the fuel is consumed.
  • Pink glass colouring: Erbium oxide imparts a distinctive rose-pink colour to glass and crystal; it is used in decorative glassware, studio glass art, and optical filter glasses that transmit pink or selective wavelengths.

Downloadable Resources

Free periodic table reference sheets for classrooms, study sessions, and laboratory use.

Colour PDF Black & White PDF

Frequently Asked Questions

What is erbium used for?

Erbium-doped fibre amplifiers (EDFAs) are essential components of long-distance fibre-optic communication networks. When erbium-doped optical fibres are pumped with laser light, they amplify 1550 nm infrared signals: the wavelength that travels furthest in silica glass: without needing to convert the signal to electricity. Erbium also imparts a pink colour to glasses and crystals, used in photographic filters and decorative glass.

Why is erbium critical for fibre-optic communications?

Optical signals in fibre-optic cables weaken over distance. Before erbium-doped fibre amplifiers (EDFAs), signals had to be converted to electrical form, amplified, and converted back to light: a costly, slow process. EDFAs, invented in the late 1980s, amplify light directly by stimulated emission from excited erbium ions at exactly the 1550 nm wavelength used in long-haul communications. This allowed the internet to scale to intercontinental distances.

How was erbium discovered?

Erbium was discovered in 1843 by Swedish chemist Carl Gustaf Mosander from yttria (yttrium oxide) extracted from the Ytterby quarry mineral gadolinite. He separated yttria into three fractions: yttria (white), terbia (yellow), and erbia (rose-coloured). There was considerable confusion about which name applied to which fraction over the following decades, but erbium was eventually assigned to the rose-pink fraction. The name comes from Ytterby.

What makes the 1550 nm wavelength special in fibre optics?

Silica glass optical fibres have their lowest transmission loss: around 0.2 dB per kilometre: at a wavelength of about 1550 nm. This wavelength sits in the C-band (conventional band) of the telecommunications spectrum. It is not a coincidence that erbium amplifies at this exact wavelength; the match between erbium's emission and silica's lowest-loss window made EDFA technology uniquely transformative for long-haul communications.