A new source of magnetic nanoparticles?

rare earths table 8200279296_66c3b6e14b_oThe hunt for a viable renewable energy to replace oil or a healthy alternative to the dreaded sugar may dominate global headlines, but the story of rare earths is a juicy one that deserves to be told. This periodic table group of elements received their somewhat undeserving moniker due to their tendency to disperse themselves in inconvenient traces throughout the Earth’s crust. Rare earths are – in fact – relatively abundant, but that doesn’t mean their use is straightforward.

Most of the problem with reliance on rare earths lies in China’s almost total control over the market. According to William Branford, Senior Lecturer in Imperial College London’s Department of Physics, “China has leverage with supplies of rare earths for political gain. It’s not like these things are only in China, it’s just that while China was playing ball it was cheaper to get them from there so everyone did,” he said.


Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) image of the Moutain Pass rare earth open cast mine in California

Now holding 95% of the world’s supply, China has spent the past 5 years trying rather successfully to drive prices skyward. In 2012, a consortium of countries led by the United States, including Canada, lodged an official complaint with the World Trade Organization against the increasing export duties and decreasing quotas appearing in China’s rare earths industry. China claimed that the measures were necessary for conservation and minimizing mining pollution, but ultimately the WTO ruled in favour of the US and gave China a deadline for rebalancing its trade policies.

Why does this global game of Monopoly matter? Rare earths provide the strongest permanent magnets available, and are found in everything from computer hard drives to electric vehicles to MRI machines in hospitals. Finding a new material that can supply the same magnetic properties has become a major driver in science funding around the world.

The European Innovation Partnership (EIP) highlights the rising prices of rare earths in its aim to help fast-track alternative materials. The Rare Earth Alternatives in Critical Technologies (REACT) program in the United States is also one of the resultant funding bodies.

Researchers at Virginia Commonwealth University in the US, with support from REACT, believe they have found a viable, rare earth-free magnetic material. Ahmed El-Gendy, a former postdoctoral associate at VCU, led the research into cobalt iron carbide (CoFe2C) synthesis. “I measured the same sample after 2 years, it still had the same magnetic properties, same corrosivity, same everything,” said El-Gendy commenting on results published in Applied Physics Letters at the end of May.

cobalt nanoparticles 3606439903_564be7de62_bWith the last of China’s illegal trade practices due to be phased out by the time this goes to press, El-Gendy is still confident his material would be able to compete in a calmer market. “Rare earths are not stable with air, they can be easily oxidized so you cannot use them outdoors. They are not easy to recycle and the vapours are very toxic,” he said.

The development of non-toxic, stable alternatives is especially exciting for medical applications. “You could treat tumours by putting magnetic nanoparticles within the tumour, then exciting them. You’re heating very locally without doing too much damage elsewhere,” Branford said. Targeted drug treatments are also a possibility. “If you bind specific drugs to individual nanoparticles and put a big permanent magnet at a certain point, then you can get all the drugs to go to one place in the body rather than being randomly distributed everywhere,” he said.

With a flood of important applications waiting intently, time will tell if the WTO’s intervention has allowed space in the market for rare earth alternatives. In the meantime, VCU plans to move forward on commercializing its novel compound, moving us one step closer to a happy ending.

Emma Brown is studying for an MSc in Science Communication

Images: Rare Earth Elements by Terence Wright; Mountain Pass Mine Wallpaper by Stuart Rankin;  Cobalt nanoparticles by victorpuntes (Flickr, Creative Commons)

Citation: Ahmed A. El-Gendy, A.A. et al. (2015) Experimental evidence for the formation of CoFe2C phase with colossal magnetocrystalline-anisotropy. Appl. Phys. Lett. 106, 213109; http://dx.doi.org/10.1063/1.4921789

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