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Researchers in the United States have showcased that a nanoscale semiconductor material can withstand extreme environments. Called graphene nanoribbons, these materials could help clear a key hurdle to bringing fusion energy to the electric grid, according to researchers from University of Arizona.
Researchers integrated the nanoribbons, known as GNRs, into semiconductor devices and exposed them to gamma radiation. Their results suggest that the ribbons could serve as radiation sensors for fusion reactors and in deep space, where intense radiation challenges existing technologies and close monitoring of material degradation could help keep critical systems operating reliably.
Nanoribbons-based sensors could help unlock fusion energy
“The devices survive the exposure and still respond, but their electrical performance changes dramatically,” said principal investigator Zafer Mutlu, University of Arizona assistant professor of materials science and engineering in the College of Engineering. “That’s exactly the behavior we want from a sensor.”
GNR-based sensors could help unlock fusion energy as a clean, near-limitless power source by improving how engineers monitor the condition of a reactor’s first wall. This innermost barrier separates the superheated fuel from the reactor structure and gradually degrades under intense radiation, requiring periodic inspection and replacement. Engineers track that damage, but today’s silicon-based sensors cannot survive inside the first wall. Instead, they must be placed outside the barrier, forcing reliance on indirect measurements during operation and physical inspection after shutdown, according to a press release.
Because the gamma exposure left the ribbons’ atomic framework intact while producing a strong, measurable electrical response, the researchers suggest GNR-based sensors could eventually be engineered to operate closer to the reactor core than today’s electronics can survive – potentially reducing costly shutdowns for inspection and maintenance and increasing the amount of time fusion power plants can remain in operation, as per the release.
Published in the journal ACS Applied Materials & Interfaces, the study investigates the structural and electronic response of atomically precise GNRs to gamma irradiation. Nine-atom-wide armchair GNRs (9-AGNRs) were synthesized via a bottom-up on-surface approach, integrated into field-effect transistors (FETs), and characterized before and after exposure using Raman spectroscopy and electrical transport measurements. Raman spectroscopy indicates preservation of the primary GNR lattice structure, accompanied by subtle spectral changes suggestive of irradiation-induced oxidation or local lattice perturbations.
Radiation exposure could provide more precise data for reactor maintenance planning
Mutlu revealed that the minuscule ribbons behave according to the rules of quantum physics rather than classical physics. In the absence of radiation, current flows in a well-defined way through GNRs, like the ones used in the study. The researchers’ measurements indicate that gamma radiation passing through the surrounding air produces reactive molecules that subtly alter the ribbon edges without changing their overall structure. At this scale, quantum effects amplify the impact of small changes on electrical signal transport through the material, as per the release.
The researchers propose that the changes trigger a quantum effect called Anderson localization, which traps charge-carrying electrons in place and sharply reduces current, producing the signal of radiation exposure that could provide more precise data for reactor maintenance planning, according to the team.
