Dysprosium

A neodymium magnet loses coercivity as it warms, and an electric-vehicle traction motor runs at 150 °C or more, so a few percent of dysprosium is substituted into the lattice to raise the anisotropy field and keep the magnet from demagnetising. That single application dominates world demand and makes dysprosium one of the most supply-constrained elements in the energy transition, which is why magnet makers spend heavily on grain-boundary diffusion techniques that place dysprosium only where it is needed rather than throughout the bulk. The name comes from Greek dysprositos, hard to get at — Lecoq de Boisbaudran needed more than thirty precipitation cycles to separate it in 1886, and the name has aged well.