ScienceDaily: Rare earth elements are metals used in technologies from wind turbines and magnetic resonance imaging agents to industrial catalysts and high-definition televisions. Most are lanthanides, elements with atomic number from 57 to 71, lanthanum to lutetium, in the periodic table. The lanthanides predominantly form trivalent cations (with a net positive charge of three). Lanthanides have similar chemical properties, and the only significant physical characteristic that distinguishes them from each other...