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Europium is a chemical element with symbol Eu and atomic number 63. Europium is one of the least abundant elements in the universe, with only about 5×10−8% in the entire universe.
E 0591 (OTTO) Europium foil, 0.8 mm thick, 99.9% Cas 7440-53-1 - used in the anti-counterfeiting phosphors in eurobanknotes. It is a dopant in some types of glass in lasers and other optoelectronic devices.