Europium (Eu)

Europium (symbol Eu) is the chemical element with atomic number 63: a lanthanide (rare earth), solid at 0 °C, with an atomic mass of 151.96 u. Discovered in 1901 (Eugène-Anatole Demarçay).

Europium is the champion of luminescence: under ultraviolet light or electron bombardment it emits a very pure red (or a blue, depending on its chemical form). It gave old cathode-ray TVs and compact fluorescent lamps their colors. It is also the most reactive and the lightest of the lanthanides.

Key facts

Atomic number: 63
Symbol: Eu
French name: Europium
Atomic mass: 151.96 u
Molar mass: 151.96 g/mol
Family: Lanthanides
Position: period 6, f-block
State at 0 °C: Solid
Melting point: 825.9 °C
Boiling point: 1,528.9 °C
Density: 5.26 g/cm³
Electronegativity (Pauling): 1.2
First ionization energy: 547 kJ/mol
Atomic radius: 185 pm
Electron configuration: [Xe] 4f⁷ 6s²
Abundance in Earth's crust: 2 ppm (52nd most abundant element)
Indicative price: 31 $/kg (order of magnitude)
Radioactive: no
Discovery: 1901, Eugène-Anatole Demarçay

Origin of the name

From Europe.

What does europium look like?

A silvery metal as soft as lead that oxidizes almost instantly in air and reacts with water. It is stored under oil or argon.

Where is europium found?

About 2 ppm of Earth's crust. It is present in small proportions in bastnäsite and monazite. Geologists study its “anomaly”: in some rocks, such as those of the lunar highlands, it is more or less abundant than its neighbors.

Natural sources

Bastnäsite
Monazite
Xenotime

How is europium produced?

Because it can adopt the +2 state, it can be reduced and then selectively precipitated, which makes separation easier. The metal is obtained by reducing the oxide with lanthanum.

Top producers

China
United States
Myanmar
Australia

What is europium used for?

Red phosphors in cathode-ray screens and fluorescent lamps.
Blue and red phosphors in some white LEDs.
Anti-counterfeiting inks that fluoresce under UV.
Control rods in nuclear reactors (neutron absorber).

In everyday life

A euro banknote under a UV lamp
A compact fluorescent bulb
An old cathode-ray-tube TV
A glow-in-the-dark label or paint

Role in living things

No known biological role; mildly toxic.

Hazards of europium

Not very toxic, but highly reactive: the metal can ignite in air at around 150 °C and reacts with water, releasing hydrogen.

Cosmic origin

Neutron stars: Created when two neutron stars collide — the “forge” of gold.

History of europium

The French chemist Eugène-Anatole Demarçay isolated it in 1901 from impure samarium and named it after Europe. Lecoq de Boisbaudran had glimpsed signs of it as early as 1890.

Did you know?

Dutch researchers showed that the red fluorescence of euro banknotes under UV comes from a europium compound — a fitting touch for an element named after Europe.
With a density of 5.2 g/cm³, it is the lightest of the lanthanides.
The switch to flat screens and LEDs sent demand for europium tumbling.

Isotopes of europium

Natural europium is an almost even mix of two isotopes, 151 and 153. Europium-151 turned out to be radioactive in 2007, with a half-life hundreds of millions of times longer than the age of the Universe.

europium-151: 47.81% of natural europium, radioactive, half-life 4.62 × 10¹⁸ years
europium-152: radioactive, half-life 13.5 years. A reference source for calibrating gamma-ray detectors.
europium-153: 52.19% of natural europium, stable
europium-154: radioactive, half-life 8.6 years
europium-155: radioactive, half-life 4.75 years

Related elements

Same family (lanthanides): Lanthanum (La), Cerium (Ce), Praseodymium (Pr), Neodymium (Nd), Promethium (Pm), Samarium (Sm), Gadolinium (Gd), Terbium (Tb), Dysprosium (Dy), Holmium (Ho), Erbium (Er), Thulium (Tm), Ytterbium (Yb), Lutetium (Lu).