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Science

For clean energy and high-tech, building stronger magnets

The periodic table seems to epitomize an older, well-established version of science that is more high school chemistry than high-tech wind turbines or fuel-efficient car engines.

But whole swaths of the periodic table that most people have never heard of are crucial for technology and clean energy generation. And in recent years, these materials, with names like neodymium and yttrium, have been threatened by shortages and international politics.

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Last year, the Department of Energy funded a $120 million Critical Materials Institute at the Ames Laboratory in Iowa, devoted to increasing production and developing substitutes that could prevent shortages.

At Northeastern University, chemical engineer Laura Lewis sums up the scientific problem she is working on with a quick demonstration: she’ll push a shallow metal dish with a slightly rusted magnet in it across a table and challenge visitors to try and pry the magnet off. It’s possible -- but very difficult.

It’s a neodymium iron boron magnet, which is crucial in applications that range from motor scooters to fighter jets. And for the past five years, its availability and price has been in doubt because of changes in China’s production and export of rare earth elements -- a class of elements found in the bottom two rows of the periodic table. That has left scientists such as Lewis trying to find whether they can engineer a substitute.

Lewis had started her research career in the 1990s, focused on trying to understand what made such rare earth “supermagnets” strong and how to make them stronger. But the government support for that kind of research tapered and she shifted focus. In 2009, Lewis was traveling in Germany when she saw a headline that wouldn’t have registered with most people: “China Tightens Grip on Rare Minerals.”

“I went, ‘Oh, boy,’ because these are used in everything -- of military relevance, energy relevance, and just stupid things like snaps for sport equipment,” Lewis said. “That started what I call the rare-earth crisis.”

Now, the issues with China’s trade controls appear to be on their way to resolution, but Lewis is focused on finding new ways to create a magnet that can compete with a rare earth supermagnet. For inspiration, she is trying to create unique configurations of atoms, but also studying naturally-occurring formations for inspiration. For example, some meteorites have a formation of iron and nickel called tetrataenite that has very strong magnetism.

In her laboratory, she uses sophisticated equipment to try and synthesize new magnets that could have similar properties.

Her efforts are just one piece of a much larger problem. In a paper published in the Proceedings of the National Academy of Sciences late last year, a group of scientists from Yale University described their efforts to quantify which materials are truly irreplaceable, providing a first stab at giving product designers and engineers a guide that could alert them if their inventions depend on a material that is basically irreplaceable, should the supply be endangered or the price go up.

“More and more, we are moving to employing elements that are the best possible ones we know about for a particular use, and the more we do that, the more difficult it is to find good substitutes,” said Thomas Graedel, a professor of industrial ecology at Yale who led that study. “We didn’t find any metal for which all of their major uses have good substitutes, which says we need them all unless we are going to change technology -- and that takes a while. There were about a dozen for which we couldn’t find any good substitutes for any of their major uses.”

Graedel said he worries most about metals that are being used in large volumes for which there aren’t good substitutes. A good example is copper, which conducts electricity; if it were to go into shortage, it would have to be replaced by far more expensive silver. His group is now working on creating a kind of index of “criticality” that incorporates the abundance, sensitivity to supply restriction, and environmental implications of the materials that we rely on in our daily lives.

Carolyn Y. Johnson can be reached at cjohnson@globe.com. Follow her on Twitter @carolynyjohnson.

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