Europium (Eu)

Europium is a chemical element with an atomic number of 63 in the periodic table of elements. It’s one of the least abundant rare-earth elements that can be traced in Earth’s crust. Being a member of the lanthanides family of periodic table elements, europium is a divalent chemical element that makes it one of the most volatile members of the lanthanide series. 

Chemical and Physical Properties of Europium

Atomic number63
Atomic weight (mass)151.964 g.mol-1
Group (number)Lanthanides
ColorA silvery-white metal
Physical stateSolid at 20°C
Half-lifeFrom 1.1(5) ms [0.9(+5−3) ms] to 13.516 years
Electronegativity according to Pauling1.2
Density5.24 g / cm−3
Melting point822°C, 1512°F, 1095 K
Boiling point1529°C, 2784°F, 1802 K
Van der Waals radiusUnknown
Ionic radiusUnknown
Isotopes9 (2 naturally occurring isotopes)
Most characteristic isotope153Eu
Electronic shell[Xe] 4f76s2
The energy of the first ionization587.6 kJ.mol-1
The energy of the second ionization1149 kJ.mol-1
Discovery dateIn 1901 by the French chemist Eugène-Anatole Demarçay

Located between barium and hafnium in the periodic system of elements, with the symbol Eu, atomic number 63, atomic mass of 151.964 g.mol-1, and electron configuration [Xe] 4f76s2, europium is a soft and ductile metal that reaches its boiling point at 1529°C (2784°F, 1802 K), while the melting point is achieved at 822°C (1512°F, 1095 K). The atomic radius of an atom of europium is 198 pm (covalent radius). 

This member of the lanthanides family of elements has an electronegativity of 1.2 according to Pauling and is the most reactive lanthanide. It easily tarnishes when it comes into contact with air at room temperature, and reacts readily with H2O molecules. Namely, it readily oxidizes in contact with oxygen from the air and forms Eu(OH)2 ∙ H2O. This rare-earth element also burns at about 150°C to 180°C. At temperatures below 1.8K, europium displays the properties of a superconductor.  

How Was Europium Discovered?

When the chemical element cerium (Ce) was discovered in 1803, the scientists had not finished their work only by determining its chemical properties. Namely, this substance continued to generate new chemical elements, thus enriching the family of rare-earth elements in the periodic system.

To begin with, the Swedish chemist Carl Mosander managed to separate lanthanum and didymium ore (a praseodymium and neodymium compound) in 1839. In 1879, the Austrian chemist Carl Auer von Welsbach (Carl Auer)

The story of the discovery of europium begins in the late 1880s. The English scientist Sir William Crookes (1832 – 1919) researched electric phosphorescence by conducting a spectroscopic analysis of a mineral sample that contained the elements ytterbium and samarium. His measurements brought up new spectral lines in the spectra absorbed by the substance. Sir Crookes firmly believed that he’s got a new chemical element in front of him, only he couldn’t derive relevant evidence from his findings and isolate it. 

Several years later, the French scientist Paul-Émile Lecoq de Boisbaudran (1838 – 1912) managed to confirm the findings of Sir William Crookes after detecting the same color lines of the spectra by using the spectroscopy technique in his experiments. However, it was the French chemist Eugene-Anatole Demarçay (1852 – 1903) who succeeded in producing a europium salt. As a spectroscopy specialist, in 1901 de Boisbaudran wrote his name among the discoverers of new chemical elements. 

Namely, by isolating the rare-earth europium metal as the oxide europia from the samarium-gadolinium concentrates, de Boisbaudran presented the next chemical element named europium to the world of science. Still, the pure metal form of europium was not isolated until recent years.  

How Did Europium Get Its Name?

This rare-earth element with beautiful phosphorescence was named after the continent of Europe, thus honoring the European scientists who have paved the way to its discovery and invested all of their knowledge and experience to determine its properties. Europa was a Phoenician princess from Greek mythology, symbolizing the beauty of the moon. It comes from the Greek word Εὐρώπη (Europe), carrying the notion of “broad, wide face”.

Where Can You Find Europium?

By the means of spectroscopy, europium was identified as a trace element in the Sun and the stars. Being one of the rarest earth elements, europium can be also found in minute amounts in the rare-earth minerals and ores, such as monazite (a thorium and yttrium mineral compound) and bastnasite (a rare earth carbonate mineral). This chemical element is also obtained from the products of nuclear fission. 

Nowadays, europium is chiefly obtained through an ion exchange process from material rich in rare-earth elements, labeled as monazite sand ((Ce, La, Th, Nd, Y) PO4). The process includes mixing Eu2O3 with a 10%-excess of lanthanum metal and exposing the mixture to heat in a tantalum crucible under high vacuum. The pure silvery-white metal is also produced by the electrolysis of the molten chloride with sodium chloride. 

The major mining locations of the europium producing ores are found in China and the United States.  

Europium in Everyday Life

The phosphorescent properties of europium as its most distinguished chemical effects makes this lanthanide suitable for the following applications:

  • Phosphorescent powder and paints of the newer generations are produced by using the salts of europium, as well as the following rare-earth elements: europium (Eu), lanthanum (La), terbium (Tb), dysprosium (Dy), holmium (Ho), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), gadolinium (Gd), erbium (Er), and thulium (Tm);
  • Europium phosphors are applied in the manufacturing of television tubes due to their ability to produce a bright red color. The europium oxide (Eu2O3) is responsible for the red pixels in television sets and the intensive brightness of fluorescent lamps. Moreover, the discovery of the europium-doped yttrium orthovanadate red phosphor made a real technological revolution in the color television industry;
  • In addition to the aforementioned application of europium, it is also used as an activator for yttrium-based phosphors;
  • When mercury vapor lamps are enriched with europium, they give out more clear and natural light;
  • As a highly efficient neutron absorber, europium is used as one of the main chemicals in the control rods of the nuclear reactors;
  • Geochemistry and petrology use europium for the dating processes related to the formation of igneous rocks;
  • Plastic enriched with europium is applied in the manufacturing of laser components;
  • Europium is applied in scientific research such as bio-imaging. In this regard, only one kilogram of europium is enough for almost one billion analyses to be conducted, which adds to the economical upside of this element;
  • Euro banknotes contain anti-forgery marks made of europium phosphors. 

How Dangerous Is Europium?

This rare-earth element plays no significant biological role and is considered to be the least toxic among the other heavy metal elements of the periodic table. If ingested, europium salts may have a mild toxic effect. However, their toxicity is not yet thoroughly researched and analyzed. 

Environmental Effects of Europium

Despite the fact that the europium dust may impose a fire and explosion hazard, this element doesn’t pose an environmental threat to either plants or animals. 

Isotopes of Europium

Europium has 34 radioactive isotopes and two naturally occurring isotopes: europium-151 (47.81 percent) and europium-153 (52.19 percent). Both of these europium isotopes are stable isotopes. On the other hand, the half-life of the europium-130 radioisotope is 0.9 millisecond which makes it the shortest living isotope of this chemical, while the europium-150 radioisotope is the longest living radioactive form of this lanthanide, with a half-life of 36.9 years.


[n 1]

ZNIsotopic mass (Da)

[n 2][n 3]


[n 4][n 5]



[n 6]



[n 7][n 8]

Spin and


[n 9][n 5]

Natural abundance (mole fraction)
Excitation energy[n 5]Normal proportionRange of variation
130Eu6367129.96357(54)#1.1(5) ms

[0.9(+5−3) ms]

131Eu6368130.95775(43)#17.8(19) ms  3/2+  
132Eu6369131.95437(43)#100# msβ+132Sm   
133Eu6370132.94924(32)#200# msβ+133Sm11/2−#  
134Eu6371133.94651(21)#0.5(2) sβ+134Sm   
β+, p (rare)133Pm
135Eu6372134.94182(32)#1.5(2) sβ+135Sm11/2−#  
β+, p134Pm
136Eu6373135.93960(21)#3.3(3) sβ+ (99.91%)136Sm(7+)  
β+, p (.09%)135Pm
136mEu0(500)# keV3.8(3) sβ+ (99.91%)136Sm(3+)  
β+, p (.09%)135Pm
137Eu6374136.93557(21)#8.4(5) sβ+137Sm11/2−#  
138Eu6375137.93371(3)12.1(6) sβ+138Sm(6−)  
139Eu6376138.929792(14)17.9(6) sβ+139Sm(11/2)−  
140Eu6377139.92809(6)1.51(2) sβ+140Sm1+  
141Eu6378140.924931(14)40.7(7) sβ+141Sm5/2+  
142Eu6379141.92343(3)2.36(10) sβ+142Sm1+  
143Eu6380142.920298(12)2.59(2) minβ+143Sm5/2+  
144Eu6381143.918817(12)10.2(1) sβ+144Sm1+  
144mEu1127.6(6) keV1.0(1) µs  (8−)  
145Eu6382144.916265(4)5.93(4) dβ+145Sm5/2+  
146Eu6383145.917206(7)4.61(3) dβ+146Sm4−  
147Eu6384146.916746(3)24.1(6) dβ+ (99.99%)147Sm5/2+  
α (.0022%)143Pm
148Eu6385147.918086(11)54.5(5) dβ+ (100%)148Sm5−  
α (9.39×10−7%)144Pm
149Eu6386148.917931(5)93.1(4) dEC149Sm5/2+  
150Eu6387149.919702(7)36.9(9) yβ+150Sm5(−)  
151Eu[n 10]6388150.9198502(26)4.62×1018 yα147Pm5/2+0.4781(6) 
152Eu6389151.9217445(26)13.537(6) yEC (72.09%), β+ (0.027%)152Sm3−  
β (27.9%)152Gd
153Eu[n 11]6390152.9212303(26)Observationally Stable[n 12]5/2+0.5219(6) 
154Eu[n 11]6391153.9229792(26)8.593(4) yβ (99.98%)154Gd3−  
EC (.02%)154Sm
155Eu[n 11]6392154.9228933(27)4.7611(13) yβ155Gd5/2+  
156Eu[n 11]6393155.924752(6)15.19(8) dβ156Gd0+  
157Eu6394156.925424(6)15.18(3) hβ157Gd5/2+  
158Eu6395157.92785(8)45.9(2) minβ158Gd(1−)  
159Eu6396158.929089(8)18.1(1) minβ159Gd5/2+  
160Eu6397159.93197(22)#38(4) sβ160Gd1(−)  
161Eu6398160.93368(32)#26(3) sβ161Gd5/2+#  
162Eu6399161.93704(32)#10.6(10) sβ162Gd   
163Eu63100162.93921(54)#6# sβ163Gd5/2+#  
164Eu63101163.94299(64)#2# sβ164Gd   
165Eu63102164.94572(75)#1# sβ165Gd5/2+#  
166Eu63103165.94997(86)#400# msβ166Gd   
167Eu63104166.95321(86)#200# msβ167Gd5/2+#  

Source: Wikipedia

List of Europium Compounds

Most often, europium occurs in the oxidation states +3 and +2 and forms hydrides, oxides, fluorides, bromides, iodides, sulphides, selenides, tellurides, as well as nitrides. The trivalent europium exhibits phosphorescence with a half-life of around 2 ms. 

  • Europium acetylacetonate
  • Europium barium titanate
  • Europium dichloride
  • Europium hydride
  • Europium(II) bromide
  • Europium(II) fluoride
  • Europium(II) sulfide
  • Europium(III) bromide
  • Europium(III) chloride
  • Europium(III) fluoride
  • Europium(III) hydroxide
  • Europium(III) nitrate
  • Europium(III) oxide

5 Interesting Facts and Explanations

  1. The europium concentration found in Earth’s crust is almost the same as the concentration of bromine
  2. The metal europium is so soft that it can be cut or dented with any hard object. 
  3. In the periodic system of elements, europium is placed among barium, hafnium, scandium, and yttrium – all labeled as rare-earth elements, despite not being so rare. This misnomer comes from the fact that the minerals these elements were obtained from are rare, but the substances extracted from them are not scarce.
  4. Europium crystallizes in a body-centered cubic lattice form. 
  5. The Austrian chemist and engineer Karl Auer is the scientist whose name is behind the invention of the gas mantle, the ferrocerium “flints” that are used in the modern lighters, as well as the metal-filament light bulb.