Neodymium

Neodymium is a silvery lanthanide with the configuration [Xe] 4f4 6s2. Its Nd^3+ ions have three unpaired 4f electrons, and because these electrons are shielded deep inside the atom, they keep their magnetic moments when the atom is bonded in a solid. That is the key to neodymium's fame. In the compound Nd2Fe14B, neodymium locks the magnetic moments of iron atoms into one preferred direction, producing magnets that resist demagnetization and store more magnetic energy than any other permanent magnet material.

Neodymium-iron-boron magnets, invented in 1982–84, made small, powerful motors possible. They are found in electric vehicle motors, direct-drive wind turbines, hard drives, earbuds and phone vibration motors. The same sharp 4f transitions that give neodymium salts a lilac colour also make Nd^3+ an excellent laser ion: Nd:YAG and Nd-glass lasers emit infrared light at about 1,064 nm, used for cutting, eye surgery and fusion research. Neodymium glass looks lavender in daylight but blue under fluorescent light. Despite its 'rare earth' label, neodymium is more abundant in the crust than cobalt or lead.

Discovery

Neodymium was separated in 1885 by Carl Auer von Welsbach in Vienna, who split didymium, previously considered a single element, into two. One fraction gave green salts (praseodymium) and the other pink-violet salts, which he named neodymium, the 'new twin'. Pure neodymium metal was first produced in 1925. The modern magnet was developed independently in the early 1980s by Masato Sagawa at Sumitomo Special Metals and by John Croat's group at General Motors.