Yttrium

Yttrium is the first element of the second transition series ([Kr]4d1 5s2), and like scandium above it, it gives up all three valence electrons to form Y3+. The ion has no d electrons, so yttrium compounds are colorless. Because of the lanthanide contraction, the Y3+ ion is almost exactly the same size as the ions of holmium and dysprosium, so yttrium is always found with the heavy rare earth elements, is extracted with them and is counted among the rare earths.

The metal is silvery and fairly stable in air thanks to a protective oxide film. Yttrium's value lies in its compounds. Yttrium aluminium garnet (YAG) crystals host neodymium in powerful industrial lasers, and cerium-doped YAG is the yellow phosphor that turns blue LED light white. Yttrium oxide stabilizes zirconia ceramics, and yttrium barium copper oxide (YBCO), discovered in 1987, was the first material to superconduct above the boiling point of liquid nitrogen.

Discovery

In 1787 Carl Axel Arrhenius, a Swedish army officer, found a heavy black mineral in a feldspar quarry at Ytterby near Stockholm. In 1794 the Finnish chemist Johan Gadolin showed that it contained a new earth, which was named yttria after the village. Yttria later turned out to be a mixture of several rare-earth oxides. Friedrich Wöhler prepared impure yttrium metal in 1828 by reducing its chloride with potassium.