Erbium (Er)

Erbium is a radioactive chemical element with an atomic number of 68 in the periodic table of elements. This rare-earth element is found in the quantity of 3.8 ppm in Earth’s crust (0.0003%). Being a member of the lanthanides family of the periodic table, erbium is also classified as a transition metal. 

Chemical and Physical Properties of Erbium

Atomic number68
Atomic weight (mass)167.259 g.mol-1
Group (number)3 (Block F – Rare earth lanthanides)
ColorA lustrous silvery-white metal
Physical stateSolid at 20°C
Half-lifeFrom 200 ms to 9.4 days
Electronegativity according to PaulingN/A
Density9.2 at 20°C
Melting point1529°C, 2784°F, 1802 K
Boiling point2868°C, 5194°F, 3141 K
Van der Waals radiusN/A
Ionic radius(+3)100 ppm
Most characteristic isotope166Er
Electronic shell[Xe] 4f126s2
The energy of the first ionization587.6 kJ.mol-1
The energy of the second ionization1149 kJ.mol-1
Discovery dateIn 1843 by Carl Gustaf Mosander

With the periodic table symbol Er, atomic number 68, atomic mass of 167.259 g.mol-1, atomic radius 175 pm, and electron configuration [Xe] 4f126s2, the pure metal form of erbium is soft and ductile. This member of the lanthanides family of elements in the periodic table has 3, 2, and 1 oxidation states. 

Erbium reaches its boiling point at 2868°C (5194°F, 3141 K) while the melting point is achieved at 1529°C (2784°F, 1802 K). It readily dissolves in acids, while it slowly reacts with oxygen and water molecules. In both ultraviolet and infrared light, erbium displays sharp absorption spectra. In addition, erbium has a hexagonal structure of closely positioned atoms. Er3+ is fluorescent and emits glowing illumination under daylight, as well as a fluorescent light.

How Was Erbium Discovered?

In 1843, the Swedish chemist Carl Gustaf Mosander (1797 – 1858) recognized the new elements erbium and terbium while analyzing the trace impurities found in erbia (the oxide of erbium) while conducting his chemical research in Stockholm, Sweden. Several decades earlier, these impurities have been detected by the Finnish chemist Johan Gadolin (1760 – 1852) while he was attempting to analyze a sample obtained from the mineral gadolinite, obtained from a mine near the small Swedish town of Ytterby.

While conducting his scientific research, Mosander detected three new oxides, which he labeled as “yttria” (yttrium oxide), ‘’erbia’’ (erbium oxide), and ‘’terbia’’ (terbium oxide). However, the Swedish chemist did not manage to isolate the pure form of erbium in his experimental attempts. A sample of pure erbium metal was not produced until 1934. That year, the two chemists Wilhelm Klemm and Heinrich Bommer attempted to reduce anhydrous erbium(III) chloride with potassium vapor. Their experiment finally produced the pure metallic form of the radioactive element erbium. 

In 1878, the French chemical scientist Jean-Charles Galissard de Marignac from the University of Geneva succeeded in isolating yet another individual substance from the erbium. It was the chemical element ytterbium which also produced another chemical element out of its impure form – the scandium element. 

The relatively pure form of Er2O3 was produced in 1905, by French chemist Georges Urbain and his American colleague Charles James, a chemistry professor at the University of New Hampshire, United States. 

How Did Erbium Get Its Name?

The name of this chemical element is given after the city where gadolinite is found – the Swedish town of Ytterby. Apart from erbium, this little village also served as naming inspiration for the chemical elements ytterbium, yttrium, and terbium.

Where Can You Find Erbium?

Being a rare-earth element, erbium is not found in nature in its elemental form. It’s obtained mostly from laterite ionic clays and the ores containing monazite, xenotime, euxenite, as well as bastnasite minerals by ion exchange and liquid-liquid solvent extraction. Traces of this chemical element can also be found in the Universe, the Sun, meteors, as well as in the ocean.

China, Russia, and Malaysia are the world’s leading countries in the production of erbium, while the list of the world’s top three countries that hold the largest erbium reserves is made up of China, CIS countries (together with Russia), and the United States. 

Erbium in Everyday Life

Broadly used in metallurgic industry, medicine, nuclear plants, application of erbium is also found in the following instances:

  • Erbium (III) oxide is used as a pink pigmented colorant for products like sunglasses, imitation gemstones, inexpensive jewelry, and porcelain glazes. For instance, erbium-stabilized zirconia (ZrO2) produces the pink colored synthetic gemstones;
  • This chemical substance is also used in beauty treatments involving erbium laser procedures, such as removal of acne scars or wrinkles;
  • Used as a photographic filter, this chemical is used to amplify the signaling properties of optical fibers;
  • Following the aforementioned use, erbium is also used in fibre-optic telecommunications as a main chemical element supporting the signal amplifiers in long-distance telephone and data cables;
  • The intermetallic compound Er3Ni displays a high magnetic heat capacity when exposed to a temperature of 4K (−269 °C, or −452 °F) which is applied in the manufacturing of regenerator materials in low-temperature cryocoolers due to the effective regenerative heat exchange properties at low temperatures;
  • This chemical substance is used in the manufacturing of safety glasses for the welders and glass-blowers;
  • The radioactive erbium substance is used for its excellent neutron absorber properties in the nuclear industry;
  • When added to alloys with metals (like vanadium), erbium lowers their hardness, thus making them more malleable and improves their workability.

How Dangerous Is Erbium?

Since erbium rarely occurs in its elemental form, it does not possess any environmental or health risk despite its radioactivity. However, the erbium compounds must be handled with care and all the required precaution measures. They are regarded as highly toxic substances and present both fire and explosion hazards when in powdery form. 

Environmental Effects of Erbium

The free elemental form of erbium is never found in the environment since it only occurs as a part of some minerals that contain all rare earth metals. 

Isotopes of Erbium

Being a radioactive substance, erbium has a total of 30 radioactive isotopes with atomic masses varying from 142Er to 177Er. The elemental form of erbium is comprised of six stable isotopes: erbium-166 (33.5 percent), erbium-168 (26.98 percent), erbium-167 (22.87 percent), erbium-170 (14.91 percent), erbium-164 (1.6 percent), and erbium-162 (0.14 percent). In addition, the primary decay products before erbium-166 are the holmium isotopes, while the primary products after it are the thulium isotopes. 

 abun­dancehalf-life (t1/2)modepro­duct 
160Ersyn28.58 hε160Ho 
165Ersyn10.36 hε165Ho 
169Ersyn9.4 dβ169Tm 
171Ersyn7.516 hβ171Tm 
172Ersyn49.3 hβ172Tm 

Source: Wikipedia

List of Erbium Compounds 

In reaction with other chemical elements, erbium easily forms fluorides, chlorides, bromides, iodides, oxides, sulfides, selenides, tellurides, nitrides, carbonyls, hydrides, and other complex compounds. The salts formed with erbium give out a characteristic pink color. In reaction with the halogen elements, erbium forms ErF3 (pink), ErCl3 (violet), ErBr3 (violet) and ErI3 (violet).

The list of common erbium compounds includes:

  • Erbium-copper (ErCu)
  • Erbium-Iridium   (ErIr)
  • Ytterbium(III) Oxide (Yb2O3)
  • Ytterbium Sulfate  (Yb2(SO4)3)
  • Ytterbium(III) Fluoride (YbF3)
  • Erbium-gold (ErAu)
  • Copper Ytterbium Oxide (Cu2O5Yb2)
  • Ytterbium(III) Chloride Hexahydrate (YbCl3.6H2O)
  • Ytterbium Acetate [Yb(CH3COO)3]
  • Ytterbium Nitrate [Yb(NO3)3]
  • Ytterbium(II)chloride (YbCl2)
  • Erbium(III) Chloride (ErCl3)
  • Erbium-silver (ErAg)
  • Ytterbium(II) Bromide (YbBr2)
  • Ytterbium(II) Telluride (YbTe)
  • Ytterbium(III) Iodide (YbI3)
  • Ytterbium(II) Selenide (YbSe)
  • Terbium(III) Chloride (TbCl3)
  • Ytterbium(II) Iodide (YbI2)
  • Ytterbium(II) Silicide (YbSi2)
  • Ytterbium(III) Sulfide (Yb2S3)

5 Interesting Facts and Explanations

  1. Despite being classified as a rare-earth element, erbium is not that rare as a substance. In fact, it is the 45th most abundant in the Earth’s crust.
  2. There’s 2×10-7 % of erbium in the Universe, with 1.8 x 10-5% being in the meteorites, 1×10-7% in the Sun, and 9×10-11% in the oceans. 
  3. Erbium is one of the first lanthanide elements that have been discovered. 
  4. The most commonly found lanthanide elements in mineral ores are cerium, lanthanum, neodymium, and praseodymium (in this particular order of occurrence).
  5. Erbium, holmium, and dysprosium share nearly identical chemical and physical properties.