A TEAM of researchers has recently observed a truly spontaneous self-healing of fractured GaAs nanowires, marking a breakthrough for nanotechnology and nano-science.
As widely observed in natural and bio-materials, several synthetic materials have now been designed with the same ability to repair their parts and functions after damage.
In recent years, the phenomenon has been observed in a range of man-made nano-structured materials; however almost of them have required some form of external intervention, such as temperature, pressure and manual fluid injection.
They could not truly self heal.
Now Curtin University’s Dr Chunsheng Lu says researchers have demonstrated inside a transmission electron microscope under near-vacuum conditions, that self-healing can occur via rebonding of Gallium (Ga) and Arsenic (As) atoms across the fracture surfaces of GaAs nanowires.
“The current research is mainly focused on a good understanding of the self-healing mechanism of fractured nanowires, and this discovery provides insights into the design of novel nanostructures with the ability of self-healing upon fracture,” he says. “In comparison with self-healing materials requiring external intervention, truly spontaneous self-healing is more efficient in repairing fractured materials. It is further approaching the self-healing process observed in biomaterials, and has the potential to greatly increase the reliability and lifetime of nanowire-based devices.
“There is also a practical interest in developing materials that can achieve multiple healing cycles, and this study reveals that GaAs nanowires possess the ability to heal themselves when subjected to repeated fractures.” Ceramic nanowires can be applied as active components and interconnects in next-generation electronic and energy industries, including nanogenerator, nanoelectronics, optoelectronics, and sensors.
Based on molecular dynamics simulations, the research demonstrated the self-healing behaviour of fractured GaAs nanowires depends on their lateral dimensions and the number of healing cycles.
The fracture surface has to be sufficiently smooth with strong surface attraction due to the electrostatic interaction in the near-field region for self-healing of GaAs nanowires to occur.
However, a large lateral dimension and repeated fracture increase the roughness of the fractured surfaces and hinder the self-healing of GaAs nanowires.
“For example, it is found that the self-healing capacity is reduced by 46% as the lateral dimension of the wire increases from 2.3 to 9.2 nm, and by 64% after 24 repeated cycles of fracture and healing,” Dr Lu says.
The research is part of an ongoing collaboration with universities and institutions in China and US, with further research aiming to discover some of the missing detail in the experimental study of GaAs nanowires and attain a comprehensive understanding on their unique mechanical behaviours.