in your element The neodymium neologism From grand challenges of nineteenth century chemistry to powerful technology in small packages, Brett F. Thornton and Shawn C. Burdette explain why neodymium is the twin element discovered twice by two Carls. n 1838, Swedish chemist Carl Mosander the glass lasing medium became important isolated lanthanum, a new metal that had for high-power applications, including laser been hiding in Berzelius’ cerium since fusion research. I 1 1803 . Two years later, he found yet another The most powerful known permanent metal in cerium — this third component was magnets are produced from the alloy 2 responsible for a purplish hue in his samples . Nd2Fe14B. Since their invention by industry He named this metal didymium, from a in 1982, these magnets have become Greek word meaning twin. Didymium shared commonplace in speakers, headphones, many chemical properties with lanthanum hard drives, high-performance electric and thus appeared to be a fraternal twin motors and generators, and even superstrong derived from the same zygotic ore. After 1878, refrigerator magnets. Their ubiquity belies when didymium’s visible spectrum was noted their uniqueness: no other permanent to vary depending on its geological source, magnets come close to the strength of the suspicions grew that didymium contained Nd2Fe14B alloy. more than one element3. Didymium would Owing to its uses in modern technologies, remain on element lists for over four decades, concerns about the supply of neodymium and it is the only element on Mendeleev’s 1869 STOCKHOLM NATUR, OXYRIA EMMA S. KARLSSON, have grown in recent years. It is generally not periodic table that does not appear on our have stuck for one of the two elements in recycled from consumer products because modern version. question5. Nevertheless, Welsbach was not of the lack of industrially feasible recovery In the early 1880s, Austrian chemist alone in using the ‘neo-’ prefix during the methods and the small mass percentage Carl Auer von Welsbach was separating rare rush of rare earth element discoveries (many present in each product. Moreover, some uses earth elements by repeatedly performing of which were spurious) in the late nineteenth of neodymium (such as in ferrocerium flints, fractional crystallizations — a tedious and century, but only his neologism stuck. fireworks and phosphors) are dispersive. The time-consuming method that relies on tiny Welsbach was regarded as a master of readily available small, powerful Nd2Fe14B solubility variations of lanthanide double commercializing his discoveries, but the magnets in cast-off electronic detritus ammonium nitrate salts. In 1885, Welsbach’s difficult separation of rare earth elements has even led to creative recycling uses — hard work paid off and led him to a new limited his options in this area. These including building equipment for chemistry element. Announcing that didymium had elements are often found together because education in schools6. ❐ been shown to consist of two elements4, he even Mother Nature finds them hard to triumphantly proposed two new names — in separate. Neodymium is second only to BRETT F. THORNTON is in the Department contrast to the established practice of only cerium in crustal abundance amongst the of Geological Sciences and Bolin Centre for naming the less-abundant component. The rare earth elements and is far more common Climate Research, Stockholm University, minor fraction that produced green salts he than many better-known elements, including 106 91 Stockholm, Sweden. named praseodymium; the major fraction he lead and tin. In ores such as monazite and e-mail: [email protected] renamed neodymium. bastnäsite, neodymium can account for SHAWN C. BURDETTE is in the No other acknowledged element has ever 12–16% of the ore. Department of Chemistry and Biochemistry, been renamed because a new element was The main application for neodymium in Worcester Polytechnic Institute, Worcester, separated from it. Nor did any contemporary the nineteenth century was mischmetal — Massachusetts 01609-2280, USA. chemists challenge this discovery grab — a blend of cerium and lanthanum e-mail: [email protected] Mosander died in 1858 and so could not containing small amounts of neodymium defend didymium. In recent years, however, and praesodymium — a component of References some voices have been raised: it has been ferrocerium, which was used as the sparking 1. Tansjö, L. in Episodes from the History of the Rare Earth Elements suggested1 that Welsbach acted pretentiously flints for lighters. After mischmetal, colouring Vol. 15 (ed. Evans, C. H.) 37–54 (Springer, 1996). 2. Scheerer, T. Pogg. Ann. 56, 479–505 (1842). and because only one new element was glass was one of the first popular applications 3. Brauner, B. Monatsh. Chem. 3, 486–503 (1882). separated from didymium, that name should for neodymium. Melting neodymium oxides 4. Welsbach, C. A. Monatsh. Chem. 6, 477–491 (1885). into glass induces tints that vary from hot 5. Enghag, P. in Encyclopedia of the Elements 373–492 (Wiley-VCH, 2004). pinks to blues depending on the ambient 6. Guidote, A. M., Pacot, G. M. M. & Cabacungan, P. M. J. Chem. Educ. light source. In lasers, neodymium-doping of 92, 102–105 (2015). La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Hf Ta W Re Os Ir 194 NATURE CHEMISTRY | VOL 9 | FEBRUARY 2017 | www.nature.com/naturechemistry ©2017 Mac millan Publishers Li mited, part of Spri nger Nature. All ri ghts reserved. .