Thirteen Exotic Elements We can’t Live Without
From indium touchscreens to hafnium-equipped moonships, the nether regions of the periodic table underpin modern technology, but supplies are getting scarce
AS YOU flick the light switch in your study, an eerie europium glow illuminates your tablet computer, idling on the desk. You unlock it, casually sweeping your finger across its indium-laced touchscreen. Within seconds, pulses of information are pinging along the erbium-paved highways of the internet. Some music to accompany your surfing? No sooner thought than the Beach Boys are wafting through the neodymium magnets of your state-of-the-art headphones.
For many of us, such a scene is mundane reality. We rarely stop to think of the advances in materials that underlie our material advances. Yet almost all our personal gadgets and technological innovations have something in common: they rely on some extremely unfamiliar materials from the nether reaches of the periodic table. Even if you have never heard of the likes of hafnium, erbium or tantalum, chances are there is some not too far from where you are sitting.
You could soon be hearing much more about them, too. Demand for many of these unsung elements is soaring, so much so that it could soon outstrip supply. That’s partly down to our insatiable hunger for the latest gadgetry, but increasingly it is also being driven by the green-energy revolution. For every headphone or computer hard-drive that depends on the magnetic properties of neodymium or dysprosium, a wind turbine or motor for an electric car demands even more of the stuff. Similarly, the properties that make indium indispensable for every touchscreen make it a leading light in the next generation of solar cells.
All that means we are heading for a crunch. In its Critical Materials Strategy, published in December last year, the US Department of Energy (DoE) assessed 14 elements of specific importance to clean-energy technologies. It identified six at “critical” risk of supply disruption within the next five years: indium, and five “rare earth” elements, europium, neodymium, terbium, yttrium and dysprosium. It rates a further three - cerium, lanthanum and tellurium - as “near-critical”.
What’s the fuss?
It’s not that these elements aren’t there: by and large they make up a few parts per billion of Earth’s crust. “We just don’t know where they are,” says Murray Hitzman, an economic geologist at the Colorado School of Mines in Golden. Traditionally, these elements just haven’t been worth that much to us. Such supplies are often isolated as by-products during the mining of materials already used in vast quantities, such as aluminium, zinc and copper. Copper mining, for example, has given us more than enough tellurium, a key component of next-generation solar cells, to cover our present needs - and made it artificially cheap.
“People who are dealing with these new technologies look at the price of tellurium, say, and think, well, this isn’t so expensive so what’s the fuss?” says Robert Jaffe, a physicist at the Massachusetts Institute of Technology. He chaired a joint committee of the American Physical Society and the Materials Research Society on “Energy Critical Elements” that reported in February this year. The problem, as the report makes clear, is that the economics changes radically when demand for these materials outstrips what we can supply just by the by. “Then suddenly you have to think about mining these elements directly, as primary ores,” says Jaffe. That raises the cost dramatically - presuming we even know where to dig.
An element’s price isn’t the only problem. The rare earth group of elements, to which many of the most technologically critical belong, are generally found together in ores that also contain small amounts of radioactive elements such as thorium and uranium. In 1998, chemical processing of these ores was suspended at the only US mine for rare earth elements in Mountain Pass, California, due to environmental concerns associated with these radioactive contaminants. The mine is expected to reopen with improved safeguards later this year, but until then the world is dependent on China for nearly all its rare-earth supplies. Since 2005, China has been placing increasingly stringent limits on exports, citing demand from its own burgeoning manufacturing industries.
That means politicians hoping to wean the west off its ruinous oil dependence are in for a nasty surprise: new and greener technologies are hardly a recipe for self-sufficiency. “There is no country that has sufficient resources of all these minerals to close off trade with the rest of the world,” says Jaffe.
So what can we do? Finding more readily available materials that perform the same technological tricks is unlikely, says Karl Gschneidner, a metallurgist at the DoE’s Ames Laboratory in Iowa. Europium has been used to generate red light in televisions for almost 50 years, he says, while neodymium magnets have been around for 25. “People have been looking ever since day one to replace these things, and nobody’s done it yet.”
Others take heart from the success story of rhenium. This is probably the rarest naturally occurring element, with a concentration of just 0.7 parts per billion in Earth’s crust. Ten years ago, it was the critical ingredient in heat-resistant superalloys for gas-turbine engines in aircraft and industrial power generation. In 2006, the principal manufacturer General Electric spotted a crunch was looming and instigated both a recycling scheme to reclaim the element from old turbines, and a research programme that developed rhenium-reduced and rhenium-free superalloys.
No longer throwing these materials away is one obvious way of propping up supplies. “Tellurium ought to be regarded as more precious than gold - it is; it is rarer,” says Jaffe. Yet in many cases less than 1 per cent of these technologically critical materials ends up being recycled, according to the United Nations Environment Programme’s latest report on metal recycling, published in May.
Even if we were to dramatically improve this record, some basic geological research to find new sources of these elements is crucial - and needed fast. Technological concerns and necessary environmental and social safeguards mean it can take 15 years from the initial discovery of an ore deposit in the developed world to its commercial exploitation, says Hitzman.
Rhenium again shows how quickly the outlook can change. In 2009, miners at a copper mine in Cloncurry, Queensland, Australia, discovered a huge, high-grade rhenium seam geologically unlike anything seen before. “It could saturate the world rhenium market for a number of years - and it was found by accident,” says Hitzman.
In the end, we should thank China for its decision to restrict exports of rare earths, says Jaffe, as it has brought the issue of technologically critical elements to our attention a decade earlier than would otherwise have happened. Even so, weaning ourselves off these exotic substances will be an immense challenge - as our brief survey of some of these unsung yet indispensable elements shows.
Bibliography
US Department of Energy, Critical Materials Strategy
American Physical Society and Materials Research Society, Energy Critical Elements
US Geological Survey, Mineral Commodity Summaries
by James Mitchell Crow
