Europium

"Europium ( /jʊˈroʊpiəm/ ew-roh-pee-əm) is a chemical element with the symbol Eu and atomic number 63. It is named after the continent of Europe. It is a moderately hard silvery metal which readily oxidizes in air and water. Being a typical member of the lanthanide series, europium usually assumes the oxidation state +3, but the oxidation state +2 is also common: all europium compounds with oxidation state +2 are slightly reducing. Europium has no significant biological role and is relatively non-toxic compared to other heavy metals. Most applications of europium exploit the phosphorescence of europium compounds."

"Europium is a ductile metal with a hardness similar to that of lead. It crystallizes in a body-centered cubic lattice.^[2]Some properties of europium are strongly influenced by its half-filled electron shell. Europium has the second lowest melting point and the lowest density of all lanthanides."

"Europium becomes a superconductor when it is cooled below 1.8 K and compressed to above 80 GPa. This is because europium is divalent in the metallic state,^[3] and is converted into the trivalent state by the applied pressure. In the divalent state, the strong local magnetic moment (J = ⁷/₂) suppresses the superconductivity, which is induced by eliminating this local moment (J = 0 in Eu³⁺)."