quasicrystals_SteinhardtStiishovite_400.jpgCatherine Zandonella recently published a fascinating account of how an international team of researchers led by Princeton University scientists discovered evidence for the extraterrestrial origins of the world’s only known sample of a naturally occurring quasicrystal. She describes the quest undertaken by physicist Paul Steinhardt, the Albert Einstein Professor in Science at Princeton, to find a quasicrystal, a mineral so exotic in structure that it was thought impossible to occur naturally. One interesting dimension of Steinhardt’s quest not detailed in previous media coverage involves the role of Nan Yao, director of the Imaging and Analysis Center at the Princeton Institute for the Science and Technology of Materials.

Here is Zandonella’s account of Yao’s role:

“When the sample arrived … it had been cut away from the surrounding rock, leaving Steinhardt with microscopic grains to work with, and no room for error. ‘If we had dropped the sample, it would have been lost forever,’ said Nan Yao, Steinhardt’s Princeton colleague. Yao painstakingly ground the tiny sample, which measured the width of a human hair, into the even smaller slivers required for probing the structure to see if it was a quasicrystal. The technique they used, transmission electron microscopy, involves firing a beam of electrons at a sample and observing how the electrons bend, or diffract, when they hit the sample.

“Within a sliver of the Russian rock, the researchers found the signature diffraction pattern of a quasicrystal, consisting of aluminum, copper and iron, embedded next to the khatyrkite and other minerals. ‘I was very excited when I saw the diffraction pattern,’ said Yao, who had come into work on New Year’s Day to do the studies when the lab was quiet.” In the image above the pink and white material is a rare mineral called stishovite, found only

in meteorites and meteorite impacts. The dark material in the middle is quasicrystal. Wow. Read the full account here.

Image courtesy Paul Steinhardt

 
css.php