Yttrium

A small feldspar quarry at Ytterby, on an island outside Stockholm, has given its name to four elements — yttrium, ytterbium, terbium and erbium — and yielded three more besides. Johan Gadolin identified the first oxide from it in 1794. Yttrium's uses are all about hosting other ions: yttrium aluminium garnet doped with neodymium is the Nd:YAG laser, the 1064 nm workhorse of industrial cutting, rangefinding and eye surgery, and yttrium oxide doped with europium was the red phosphor in every colour television tube. In 1987 Paul Chu's group substituted yttrium into a lanthanum-barium-copper oxide and got YBCO, superconducting at 93 K — the first material to work above the boiling point of liquid nitrogen, which turned superconductivity from a liquid-helium speciality into practical engineering.