Eu - Europium
|Chemical Element||Europium||Melting Point °C||822|
|Chemical Symbol||Eu||Boiling Point °C||1597|
|Atomic Number||63||Density g/cm3||5.2|
|Atomic Weight||151.965||Oxide||EuO, Eu2O3|
Europium is a soft, silvery metal, rather like lead. Europium belongs to the lanthanoid group of elements within the Periodic Table. Europium is one of the rarest rare earth metals and also the most reactive. This metal oxidizes rapidly in air and reacts with water to produce hydrogen. When heated to a temperature of about 180°C, it will ignite spontaneously.
The history of europium begins with the discovery of cerium in 1803. From cerium, the chemist Carl Gustav Mosander was able to extract a new element, lanthanum, and didymium which turned out to be a mixture of mainly praseodymium and neodymium. From didymium another much rarer element was later found, this element was samarium. The sample of samarium was also later found to be impure, and in 1886, Jean Charles Galissard de Marignac was able to extract yet another rare earth from it. This element was called gadolinium. But despite this, when analysing the atomic spectrum of samarium, there were still unexplained lines appearing, which could only mean that there must be yet another new element present. Eventually, in 1901, the French chemist, Eugene Anatole Demarcay was able to extract this new element, which he named europium.
Although europium is found in high quantities in minerals such as calcium speldstars (calcium aluminium silicates), this is not used as a commercial source, and instead it is mined from the rare earth minerals, monazite and bastnasite, which are sources for all the lanthanoid elements. Europium is not a major component, but it is found in extractable amounts, and is one of the more abundant lanthanoids. Monazite contains all of the rare earth elements, often in concentrations of up to 50%. Monazite can be found in river sand in countries such as India, Brazil and South Africa. Bastnasite deposits can be found in the Mojave Desert in California. World production of rare earth ores is mostly from China, normally as europium oxide, and in 2010 world production was estimated at 390 mt. Pure europium metal production is around 270 mt per year.
Europium oxide (Eu2O3) has a vital role to play in colour televisions and computer display screens as a phosphor for emitting a pure red light. It is this red spectrum that also causes europium to be used in low-energy light bulbs to create a more ‘natural’, warm light instead of the cold glare of traditional fluorescent tubes. Europium is also added to mercury vapour tubes to give powerful street lighting a more natural light. Europium is employed in the medical field, as the highly sensitive luminescence provided by europium, attached as a tag to complex biochemicals, assists in live tracing of these materials during living tissue research. Given that almost all practical uses of europium utilise its luminescent properties, europium oxide is the commonly traded form.
- Emsley, John. Nature’s Building Blocks, An A-Z Guide to the Elements, New Edition, Oxford University Press, 2011
- Gray, Theodore. The Elements, A Visual Exploration of Every Known Atom in the Universe, Black Dog & Leventhal Publishers, Inc, NY, 2009
- Stwertka, Albert. A Guide to the Elements, 3rd Edition, Oxford University Press, 2012