in your element All manner of antimony Claire Hansell surveys the uses, past and present, for antimony, including an unusual method for ‘recycling’ it. raversing the periodic table, there One of the major current uses for are few elements whose chemical element 51 is the incorporation of antimony symbols are not derived from their full trioxide as a flame retardant into plastics T 4 (English) name. Most are from the handful and other materials . Alloying antimony of metals known since antiquity. Whilst iron, with other metals has also long been gold or silver might spring immediately to used as a tactic to improve hardness mind, antimony is also part of this venerable and tensile strength; when Gutenberg ‘old world’ of elements. Its symbol Sb comes invented the printing press in the 1400s, from the Latin stibnum, which also lends its the metal type blocks were made from a name to the mineral in which antimony is lead–tin–antimony alloy. Today similar most commonly found: stibnite (Sb2S3), used alloys are used for the plates in lead–acid by Ancient Egyptians as an eye cosmetic batteries. Elemental antimony is also owing to its rich black colour. considered to be a promising anode Ancient Greek and Latin authors material for high-energy density lithium referred to it using variants of the name Orange deposits of antimony pentasulfide (Sb2S5) ion batteries, owing to its high theoretical stibium, so where did ‘antimony’, the at Champagne Pool, Rotorua, New Zealand. capacity when lithiated to Li3Sb. medieval term that has stuck until the © Robert Harding World Imagery / Alamy With the ever-increasing interest in present day, come from? A popular, but more efficient semiconducting materials to most likely fanciful, etymology is that further miniaturize transistors in integrated it is derived from the French antimoine Antimony is poisonous by inhalation circuits, doping non-metals with antimony meaning anti-monk. Many early alchemists and ingestion, and it has also been found has also found use. Doped zinc oxide has were monks who believed it was possible to to be carcinogenic1, although the exact been shown to act as a p-type (electron- transform antimony into gold — but were mechanisms of its toxicity are still unclear. conducting) semiconductor, and under unfortunately unaware of its toxicity and This, however, hasn’t prevented element 51 certain oxidizing conditions can also conducted alchemical experiments with not from finding a role in medicine throughout result in a ceramic with variable resistance a lab coat or safety goggles in sight. More history. As well as eye make-up, stibnite was properties. Doping silicon to increase its likely though is that the name derives from used as a skin medication in Ancient Greece. hole-conducting properties (as an n-type the Greek ἀντίμόνος (antimonos), meaning In the Middle Ages, it was widespread semiconductor) is also under investigation5. against aloneness, reflecting the fact that practice for pellets of antimony to be From ancient times to the present day, element 51 is rarely found naturally in its swallowed whole to induce vomiting and as from use of both the bulk metal and stibnite metallic state. a laxative; this was in tune with the medical through to the careful incorporation of tiny A metalloid, rather than a true metal, belief of the times that ‘bad humours’ amounts in alloys and ceramics, antimony antimony exists in four allotropes: the needed to be expelled from the body. It has found all manner of applications. Future most stable is metallic and grey; with was an expensive metal, and so pellets were developments in electronics may well hinge a non-metallic yellow, a black and often retrieved for re-use, and even passed on the precise location and environment of an explosive white form also known. on from generation to generation — whilst antimony atoms, arranged with just as much Unusually, metallic antimony expands not the best medicine, this was certainly care as an Ancient Egyptian queen applying slightly upon freezing, one of only four an innovative recycling method! A more stibnite-based make-up. ❐ elements known to do so. It generally forms refined alternative, generally used in the compounds in its trivalent and pentavalent 1600s after the pellets were outlawed, was to CLAIRE HANSELL is an editor at Nature. states. One example is the powerful drink wine that had been left standing in an e-mail: [email protected] Lewis acid SbF5, which in combination antimony cup overnight. with HF forms fluoroantimonic acid Far from being an effective medical References 2 1. Beyersmann, D. & Hartwig, A. Arch. Toxicol. 82, 493–512 (2008). ([H2F][SbHF6]), the strongest known treatment, it has been suggested that 2. Guillery, E. N., J. Am. Soc. Nephrol. 2, 1671–1676 (1992). superacid (pH −31.3), which is even excessive use of antimony therapy may 3. Murray, H. W., Berman, J. D., Davies, C. R. & Saravia, N. G. able to protonate hydrocarbons to form have contributed to Mozart’s early death at Lancet 366, 1561–1577 (2005). carbocations and molecular hydrogen. just 35. Today some pentavalent antimony 4. Grund, S. C., Hanusch, K., Breunig, H. J. & Wolf, H. U. Antimony compounds have found proper medical use and Antimony Compounds. (Ullmann’s Encyclopedia of Industrial 3 Chemistry, Wiley, 2006). as treatments for leishmaniasis , a parasitic 5. Voyles, P. M., Muller, D. A., Grazul, J. L., Citrin, P. H. & disease mostly found in the developing world. Gossmann, H.‑J. L. Nature 416, 826–829 (2002). Cd In Sn Sb Te I Xe Cs Ba La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er 88 NATURE CHEMISTRY | VOL 7 | JANUARY 2015 | www.nature.com/naturechemistry © 2014 Macmillan Publishers Limited. All rights reserved.