An international team of scientists, including two physicists from Northeastern University, have developed an entirely new material spun out of boron, nitrogen, carbon and oxygen that shows evidence of magnetic, optical, electrical and thermal properties. Its potential applications run the gamut: from 20-megapixel arrays for cellphone cameras to photodetectors to atomically thin transistors. The material is detailed in a recent paper in Science Advances.
"We had to start from scratch and build everything," says Swastik Kar. "We were on a journey, creating a new path, a new direction of research." This material came out of a four-year project, funded by the US Army Research Laboratory and the US Defense Advanced Research Projects Agency (DARPA), to imbue graphene with thermal sensitivity for use in infrared imaging devices such as night-vision goggles for the military.
Kar and his colleague Srinivas Sridhar started by adding boron and nitrogen to graphene to convert it into an electrical insulator. They also spent a lot of time trying to prevent oxygen from seeping into their brew, worried that it would contaminate the "pure" material they were seeking to develop. "That's where the Aha! moment happened for us," says Kar. "We realized we could not ignore the role that oxygen plays in the way these elements mix together."
"So instead of trying to remove oxygen, we thought: Let's control its introduction," adds Sridhar. Oxygen, it turned out, was behaving in the reaction chamber in a way the scientists had never anticipated: it was determining how the other elements – the boron, carbon and nitrogen – combined in a solid, crystal form, while also inserting itself into the lattice. The trace amounts of oxygen were "etching away" some of the patches of carbon, explains Kar, making room for the boron and nitrogen to fill the gaps. "It was as if the oxygen was controlling the geometric structure," says Sridhar.
They named the new material 2D-BNCO, reflecting the four elements in the mix and the two-dimensionality of the super-thin lightweight material, and set about characterizing and manufacturing it, to ensure it was both reproducible and scalable. That meant investigating the myriad permutations of the four ingredients, holding three constant while varying the measurement of the remaining one multiple times over.
After each trial, they analyzed the structure and the functional properties of the product using electron microscopes and spectroscopic tools, and collaborated with computational physicists, who created models of the structures to see if the configurations would be feasible in the real world. Next, they will examine the new material's mechanical properties and begin to validate the magnetic ones conferred by the intermingling of these four nonmagnetic elements. "You begin to see very quickly how complicated that process is," says Kar.
Helping with that complexity were collaborators from around the globe. In addition to Northeastern associate research scientists, postdoctoral fellows and graduate students, contributors included researchers in government, industry and academia from the US, Mexico and India.
“There is still a long way to go but there are clear indications that we can tune the electrical properties of these materials," says Sridhar. "And if we find the right combination, we will very likely get to that point where we reach the thermal sensitivity that DARPA was initially looking for as well as many as-yet-unforeseen applications."
This story is adapted from material from Northeastern University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.