#antisite defect

[materialsscienceandengineering]

An antisite defect ( 2 ) is a type of point defect in which atoms in an alloy switch positions (an A atom on a B site, and a B atom on an A site). It is also known as an atom interchange, and is common in alloys with similarly sized elements, such as copper-gold-silver alloys and semiconducting compounds such as GaAs.

Image 1.

[materialsscienceandengineering]

Study reveals unknown details about common lithium-ion battery materials

High-performance electrodes for lithium-ion batteries can be improved by paying closer attention to their defects—and capitalizing on them, according to Rice University scientists.

Rice materials scientist Ming Tang and chemists Song Jin at the University of Wisconsin-Madison and Linsen Li at Wisconsin and the Massachusetts Institute of Technology led a study that combined state-of-the-art, in situ X-ray spectroscopy and modeling to gain insight into lithium transport in battery cathodes. They found that a common cathode material for lithium-ion batteries, olivine lithium iron phosphate, releases or takes in lithium ions through a much larger surface area than previously thought.

"We know this material works very well but there's still much debate about why," Tang said. "In many aspects, this material isn't supposed to be so good, but somehow it exceeds people's expectations."

Part of the reason, Tang said, comes from point defects—atoms misplaced in the crystal lattice—known as antisite defects. Such defects are impossible to completely eliminate in the fabrication process. As it turns out, he said, they make real-world electrode materials behave very differently from perfect crystals.

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