Yttrium

About Yttrium

Yttrium is grouped with the rare earths even though it sits in period 5 — its ionic radius (Y³⁺ ≈ 90 pm) is close enough to the heavy lanthanides like holmium and erbium that it co-precipitates with them through every separation step, which is why Gadolin pulled it out of the same Ytterby black mineral that eventually yielded another nine elements. The name 'rare earth' is misleading: yttrium is more abundant in the crust (~33 ppm) than lead. Y³⁺ is the only oxidation state that matters in practice, which simplifies the chemistry but makes the solvent-extraction separation from the lanthanides tedious. The two applications that drive demand both depend on yttrium acting as a host lattice for other ions: Y₃Al₅O₁₂ (YAG) doped with Nd³⁺ gives the 1064 nm laser that runs every machine shop and cataract clinic, and Y₂O₃ doped with Eu³⁺ has been the red phosphor in CRTs and is still used in tri-band fluorescent lamps. The third major use is YBa₂Cu₃O₇ (YBCO), the first material that superconducted above the boiling point of liquid nitrogen.