The names of the rare earth elements may not trip off the tongue of the person on the street but that’s not to say that they haven’t found uses in modern life. Here are five of this first row of the f-block, represented by their applications. Although I’ve plumped for a particular use for a particular element, several of these patterns could have been used for others in the series as the properties of many of these elements are pretty similar and their uses often interchangeable.
Element 62, samarium: samarium-cobalt magnets are second only in strength to neodymium magnets and can withstand significantly higher temperatures. They have found use in headphones, pickups for electric guitars, personal stereos and small motors.
Element 64, gadolinium, also has magnetic properties and finds use as a contrast agent in magnetic resonance imaging. But it has also found its way into our homes as the green phosphor in cathode-ray tube televisions. I couldn’t help recalling Evil Edna from the 1980s cartoon Willo the Wisp when designing this pattern – the distinctive voice of Kenneth Williams is one of the memorable sounds of my childhood.
Element 65, terbium, was used in the first re-writable compact discs. It is also used in the green phosphors in plasma screens and in a variety of motors from wind turbines to vacuum cleaners.
Element 66, dysprosium: as a component of the alloy Terfenol-D (where D stands for dysprosium and Ter for terbium), this element finds use in sonar sytems. The alloy is magnetostrictive: it expands and contracts in a magnetic field.
Element 70, ytterbium: as a gamma-ray source, ytterbium-169 is used in portable X-ray machines requiring no power supply. Its neighbour thulium also finds the same use.
Thanks to the cover design of Hugh Aldersley-Williams’ fascinating Periodic Tales for the inspiration for samarium, to the RSC’s Visual Elements Periodic Table and associated podcasts for gadolinium, terbium and dysprosium, and to Compound Interest for ytterbium.