Nanotechnology Now - Press Release: Bending world’s thinnest glass shows atoms’ dance

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Elastic and plastic deformation in ring exchange. (A) Cartoon models of the 2D silica structure. (B-E) TEM images showing a ring rearrangement that transforms a 5-7-5-7 cluster into a 6-6-6-6 cluster. (G) Larger view of the region from part A, and (H) corresponding first-to-last frame displacement map. (H) The region between the bond rearrangement and the edge of the sheet exhibits strong local rotation. Scale bars 1 nm.

Abstract:
Watch what happens when the world's thinnest sheet of glass discovered by researchers from Cornell University and the University of Ulm featured in the Guinness Book of World Records, breaks. Well, not exactly breaks, but close to it. A research team led by David A. Muller, professor of applied and engineering physics and co-director of the Kavli Institute at Cornell for Nanoscale Science and Ute Kaiser from the University of Ulm, who both led the previous study on atomically thin glass, has used an electron microscope to bend, deform and melt the one molecule-thick glass. These are all things that happen just before glass shatters, and for the first time, the researchers have directly imaged such deformations and the resulting "dance" of rearranging atoms in silica glass, which forms the basis for everyday windowpanes. This newest work is published Oct. 11 in the journal Science.

Bending world’s thinnest glass shows atoms’ dance

Ulm, Germany | Posted on October 16th, 2013

Glass, what's known as an amorphous solid because its atoms are rigid like a crystal but disorderly like a liquid, is notoriously hard to study, said Pinshane Huang, a graduate student working with Muller and the paper's first author.

"Now, instead of just looking at its structure, we are looking at its dynamics and how it bends and breaks," Huang said. "This thinnest-ever glass gives us a new way of looking at glasses at the single-atom level, and how they break atom by atom." Added Muller: "No one has ever before been able to see the rearrangements of atoms in a glass when you push on it."

Sophisticated theories describe how these atoms behave when bent or broken, but only on the computer, said Jim Sethna, professor of physics and paper co-author. "Lots of people have made computer simulations, but this is the experimental realization of what the glass community has been looking for a long, long time."

With collaborators at both Cornell and Germany's University of Ulm, the researchers imaged the thin glass with two types of transmission electron microscopes. The electron beam heated up the glass, causing visible structural deformation at the interfaces between liquid and solid phases. Muller described the electrons as "tickling" the glass in order to deform it and simultaneously image what was happening.

To do their study, the researchers borrowed longstanding theories and predictions from scientists who study colloids - suspensions of particles in liquid that are representative of atoms but can be observed directly because they are larger.

"A lot of what we did was to use their methods and tracking codes and ideas, and now that we can actually see atoms in a glass, we tried it with real atoms," Huang said.

The work was supported by the National Science Foundation, Cornell Center for Materials Research and Air Force Office of Science Research.

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About University of Ulm
Founded in 1967, the University of Ulm enjoys an excellent reputation for innovative research, interdisciplinarity and successful training. Its 4 faculties (Engineering and Computer Science; Mathematics and Economics; Medicine; Natural Sciences) support some 9,500 students. The university plays a central role of the Science City of Ulm, not only as the region's biggest educational facility, but also as an important motor for R&D.
The research profile of the youngest university in the state of Baden-Württemberg is characterized by its focus on life sciences and medicine, bio-, nano- and energy-materials, financial services and their mathematical methodology as well as communications-, information- and quantum-technology.

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Contacts:
Annika Bingmann

Contact in Germany/ University of Ulm:

Prof. Dr. Ute Kaiser

phone +49 (0)731 / 50 - 229 50
mobil phone number can be requested from +49 (0)731 / 50 - 220 24;

Contact – USA Cornell:

Anne Ju
(607) 255-9735