12-05-2025
Groundbreaking accordion effect makes graphene more stretchable by removing atoms
Austrian researchers have unlocked a groundbreaking property of graphene, making it significantly more stretchable by manipulating its structure to ripple like an accordion using a one-of-a-kind method that has never been seen before.
The unique technique, pioneered by scientists at the University of Vienna and the Vienna University of Technology, involved the meticulous manipulation of the atomic structure of graphene, a material extracted from graphite and is made up of pure carbon, in an ultra-clean, airless environment.
This unique setup ensured that the graphene samples remained free from ambient air and foreign particles, which could interfere with the measurements and distort the results.
Jani Kotakoski, PhD, a physics professor at the University of Wien and lead author of the research, believes the discovery opens up exciting new possibilities for the material, enabling its use in applications requiring enhanced flexibility, such as wearable electronics and advanced flexible devices.
In 2004, the discovery of graphene by researchers Andre Geim, PhD, and Kostya Novoselov, PhD, from the University of Manchester, revolutionized science, introducing a new class of materials known as two-dimensional (2D) solids.
These materials, just a single atom thick, possess unique properties that hold significant promise for various applications, with graphene being particularly celebrated for its exceptional electrical conductivity, flexibility, lightness and high resistance.
However, its extreme stiffness, a result of its honeycomb-shaped arrangement of the atoms, has limited its use in many applications. Although removing atoms from its structure might be expected to reduce its stiffness, studies have yielded mixed results, with some research suggesting a slight decrease in rigidity, while others show an increase in stiffness.
Now, to address the issue, the research team conducted experiments in an ultra-clean, airless environment, using state-of-the-art equipment to ensure that the graphene samples were completely isolated from external air and contaminants. The controlled setup allowed researchers to carry out precise measurements, eliminating interference from airborne particles that might have affected the accuracy of the results.
"This unique system we have developed in the University of Vienna allows us to examine 2D materials without interference," Kotakoski explained. "For the first time this kind of experiment has been carried out with the graphene fully isolated from ambient air and the foreign particles it contains. Without this separation, these particles would quickly settle on the surface affecting the experiment procedure and measurements."
According to Kotakoski, the breakthrough came from an intense focus on keeping the graphene surface completely clean during testing. The researchers discovered that removing just two neighboring atoms from the otherwise flat material caused it to bulge slightly.
As more of these small bulges formed, they created a corrugated, wave-like structure, which the scientists have called the 'accordion effect.'
"You can imagine it like an accordion," Joudi explained in a press release. "When pulled apart, the waved material now gets flattened, which requires much less force than stretching the flat material and therefore it becomes more stretchable."
The findings were further backed by computer simulations from theoretical physicists Rika Saskia Windisch, MSc, and Florian Libisch, PhD, at the Vienna University of Technology, which confirmed the formation of these atomic ripples and the resulting increase in flexibility.
The experiments also revealed that contamination from foreign particles on the material's surface completely suppresses the accordion effect. In fact, their presence can make the material seem stiffer, providing a likely explanation for conflicting data in earlier studies.
"This shows the importance of the measurement environment when dealing with 2D materials," Joudi concluded. "The results open up a way to regulate the stiffness of graphene and thus pave the way for potential applications."
The study has been published in the journal Physical Review Letters.
