Rare earth elements vital to electronics industry
What do ics, lasers, optical fibres, capacitors, displays and headphones have in common? Answer: they are all electronic products that depend on one or more of the rare earth elements. And that list is far from complete.
There are 17 rare earth elements, all vital to the electronics industry in some form. Yet, despite their name, some rare earth element
s are relatively plentiful: cerium is, apparently, as abundant as copper. They are regarded as ‘rare’ because deposits of these elements are generally not exploitable commercially.
Though typically used in relatively small quantities per product, a major worry has emerged recently about the guaranteed continuation of their supply – some 97% of rare earths are currently supplied by China.
Over the last few years, China has been reducing its exports of rare earths and recently cut back more drastically, by around 70%
. And an ominous note was sounded when China completely halted supplies to Japan after a row about Japan’s arrest of a Chinese boat captain. He was released and supplies resumed. Squabbles aside, the prediction is that, within a few years, China will need its entire output of rare earths to satisfy its own domestic demand.
So action is being taken to avoid the drastic scenario of the supply of rare earths simply coming to a halt (see below). If it did, it is astonishing how many electronic products we use every day would become either much more difficult – even impossible – to make or much more expensive.
Take one of the most widely used rare earths – neodymium. It was first used to generate the light in green laser pointers, but then it was found that, when mixed with iron and boron, neodymium makes magnets that are weight for weight 12 times stronger than conventional iron magnets. Result: neodymium magnets are used in in-ear headphones, microphones, loudspeakers and hard disk drives, as well as electric motors for hybrid cars and generators.
Where low mass is important, they are vital: for example, in laptops, they provide finer control in the motors that spin the hard disk and the arm that writes and reads data to and from it, allowing much more information to be stored in the same area.
In its Critical Materials Strategy, the US Department of Energy (DoE) estimates new uses of neodymium, in products like wind tu
rbines and electric cars, could make up 40% of demand in an already overstretched market, which is why any shortages would be critical.
Most of the rare earths vital to electronics are less well known: erbium is one example, a crucial ingredient in optical fibres. For long distance optical fibre transmission, amplification is vital and is achieved with the help of erbium. Embedded within short sections of the optical fibre, excitable ions of erbium are pushed into a high energy state by irradiating them with a laser. Light signals travelling down the fibre stimulate the erbium ions to release their stored energy as more light of precisely the correct wavelength, amplifying the signals.
Tellurium is an element that could see a huge increase in demand because in 2009, solar cells made from thin films of cadmium telluride became the first to outdo silicon panels in terms of the cost of generating a Watt of electricity. Until now, there has been little interest in tellurium, but if it leads to significantly cheaper solar power, demand will rocket and that is why the DoE anticipates potential shortages by 2025.
Hafnium is another rare earth proving itself vital to the semiconductor industry; hafnium oxide is a highly effective electrical ins
ulator. It outperforms the standard transistor material, silicon dioxide, in reducing leakage current, while switching 20% faster. It has been a major factor in enabling the industry to move to ever smaller process nodes.
Also central to semiconductors is tantalum, key to billions of capacitors used worldwide in products like smartphones and tablet computers. In its pure form, this metal forms one of two conducting plates on which charge is stored. As an oxide, it is an excellent insulator, preventing current leakage between the plates, and is also self healing, reforming to plug any current leakage.
One of the most widely used rare earths is indium, which we all spend a lot of time looking at. The alloy indium tin oxide (ITO) provides the rare combination of both electrical conductivity and optical transparency, which makes it perfect for flat screen displays and tvs,
where it forms the see through front electrode controlling each pixel. A layer of ITO on a smartphone’s screen gives it the touch sensitive conductivity to which we have been accustomed in the last few years. Mixed with other metals, indium becomes a light collector and can be used to create new kinds of solar cells, together with copper and selenium.
Another rare earth valuable for its magnetic properties is dysprosium. When mixed with terbium and iron, it creates the alloy Terfenol D, which changes shape in response to a magnetic field; a property known as magnetostriction. Dysprosium can also handle heat
; while magnets made from a pure neodymium-iron-boron alloy lose magnetisation at more than 300°C, adding a small amount of dysprosium solves the problem. This make the element invaluable in magnets used in devices such as turbines and hard disk drives.
Other rare earths include: technetium, used in medical imaging; lanthanum and, the main components of a ‘mischmetal’ (an alloy of rare earth elements) used to create the negative electrode in nickel metal hydride batteries – and cerium also helps to polish disk drives and monitor screens; yttrium, important in microwave communication, and yttrium iron garnets act as resonators in frequency meters; and europium and terbium.
The last have been used for decades to produce images in colour tvs, thanks to their phosphorescent properties – terbium for yellow-green and europium for blue and red. More recently, energy saving compact fluorescent light bulbs have used them to generate the same warm light as the incandescent tungsten bulbs they replaced.
Is there a single reason why the rare earths have proved so valuable for such a range of technologies? The answer is no – it is more a result of each element’s particular physical characteristics, notably the electron configuration of the atoms, according to one of the world’s leading experts, Karl Gschneidner, a senior metallurgist at the DoE’s Ames Laboratory.
“Some of the properties are quite similar; basically, their chemical properties. That is why they are difficult to separate from each other in their ores and that is why they are mixed together in the ores. But many of the physical properties vary quite a bit from one another, especially those which depend upon the 4f electron (a particular electron shell in the configuration of the atom), that is the magnetic, optical and electronic properties. Even some of the physical properties, which are not directly connected to the 4f electrons, vary considerably. For example the melting points vary from 798°C for cerium to 1663°C for lutetium.”
What makes the rare earths so special is the way they can react with other elements to get results that neither could achieve alone, especially in the areas of magnets and phosphors, as Robert Jaffe, a Professor of Physics at MIT, explains.
“The result is high field strength, high coercivity, light weight magnets, clearly valuable in tiny devices where magnetically stored information has to be moved around, like hard disk read/write operations. The magnetic properties of pure metals and relatively simple alloys have been thoroughly explored and there is nothing as good as rare earth magnets. Two paradigms for magnetic material are NeBFe (neodymium-boron-iron) and SmCo (samarium-cobalt), with the former most popular now.
“In phosphors, europium, terbium and others absorb high frequency light and then re emit the light in regions of the spectrum that are very useful in manipulation of colour, hence their use in flat panel displays and compact fluorescent lights.”
Another example is neodymium oxide, which can be added to crt glass to enhance picture brightness by absorbing yellow light waves. Neodymium has a strong absorption band centred at 580nm, which helps clarify the eye’s discrimination between reds and greens.
Given how vital they are for the electronics industry and other technologies – by one estimate, £3trillion worth of industries depend on them – it is remarkable that the world has been so complacent about sourcing rare earths, allowing a single country to virtually monopolise the supply. But that is now changing.
For example, the Mountain Pass mine in California is being reactivated by Molycorp Minerals in a $781million project, having been mothballed in 2002. Others include the Nolans and Mount Weld Projects in Australia, a site at Hoidas Lake in Canada, Lai Chau in Vietnam and others in Russia and Malaysia.
In Elk Creek, Nebraska, Canadian company Quantum Rare Earth Development is drilling to look for supplies and has called on President Obama to move aggressively to create a stockpile of rare earths.
Another associated problem is the lack of people with rare earth expertise, as Gschneidner says.
“There is a serious lack of technically trained personnel to bring the entire rare earth industry – from mining to OEMs – up to full speed in the next few years. Before the disruption of the US rare earth industry, about 25,000 people were employed in all aspects. Today, there are only about 1500.”
Despite these moves, it could be years before they enhance supplies significantly. For the longer term, there are prospects of better sources emerging. Just a couple of months ago, Japanese scientists from the University of Tokyo announced they had found the minerals in the floor of the Pacific Ocean in such high density that a single square kilometre of ocean floor could provide 20% of current annual world consumption. Two regions near Hawaii and Tahiti might contain as much as 100billion tonnes.
The team was led to the sea floor because they reasoned that many rock samples on land containing metallic elements were originally laid down as ocean sediments. “It seems natural to find rare earth element rich mud on the sea floor,” they said.
A final extraordinary fact about rare earths is that, despite their importance, we have hardly bothered to recycle them at all. In an age when metals like aluminium, copper, lead and tin have recycling rates of between 25% and 75%, it is estimated that only 1% of rare earths are recycled. Japan alone is estimated to have 300,000 tons of rare earths in unused electronic goods. If we do not correct that quickly, over the next few years at least, rare earths could live up to their name with a vengeance.
Author
David Boothroyd
Source: http://www.newelectronics.co.uk
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
Precious Metals: Is Tellurium the new Gold?
Gold has been spectacularly popular among investors for the past couple of years.
Silver seems to be this year’s gold.
So, what’s next year’s silver gonna be?
According to Robert Jaffe, a physicist at MIT, tellurium could be a metal investor’s best new play.
“Tellurium ought to be regarded as more precious than gold — it is; it is rarer,” he tells New Scientist magazine.
An article by James Mitchell Crow in the June, 2011 issue of New Scientist, titled “13 Exotic Elements We Can’t Live Without,” points out:
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”.
Here are the 13 elements necessary for cleantech applications that may be winners in this year’s commodities portfolio:
Neodymium
New Scientist says:
These numerous uses make for a perfect storm threatening future supplies. In its Critical Materials Strategy, which assesses elements crucial for future green-energy technologies, the US Department of Energy estimates that wind turbines and electric cars could make up 40 per cent of neodymium demand in an already overstretched market. Together with increasing demand for the element in personal electronic devices, that makes for a clear “critical” rating.
Erbium
New Scientist says:
Erbium is a crucial ingredient in the optical fibres used to transport light-encoded information around the world. These cables are remarkably good at keeping light bouncing along, easily outperforming a copper cable transporting an electrical signal. Even so, the light signal slowly fades as it racks up the kilometres, making amplification necessary.
Tellurium
New Scientist says:
In 2009, solar cells made from thin films of cadmium telluride became the first to undercut bulky silicon panels in cost per watt of electricity generating capacity.
Because the global market for the element has been minute compared with that for copper - some $100 million against over $100 billion - there has been little incentive to extract it. That will change as demand grows, but better extraction methods are expected to only double the supply, which will be nowhere near enough to cover the predicted demand if the new-style solar cells take off. The US DoE anticipates a supply shortfall by 2025.
Hafnium
Hafnium’s peerless heat resistance has taken it to the moon and back as part of the alloy used in the nozzle of rocket thrusters fitted to the Apollo lunar module. Since 2007, though, it has also been found much closer to home, in the minuscule transistors of powerful computer chips.
That’s because hafnium oxide is a highly effective electrical insulator. Compared with silicon dioxide, which is conventionally used to switch transistors on and off, it is much less likely to let unwanted currents seep through. It also switches 20 per cent faster, allowing more information to pass. This has enabled transistor size to shrink from 65 nanometres with silicon dioxide first to 45 nm and now to 32 nm.
By Justin Rohrlich June 20, 2011
