October_AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | O C T O B E R 2 0 2 0 6 NANOTECHNOLOGY MODELING NANOCLUSTERS At the University of Pittsburgh’s Swanson School of Engineering, the Computer-Aided Nano and Energy Lab (CANELa) is advancing the field of nano- technology, modeling metal nanoclus- ters that are atomically precise in struc- ture. With a better understanding of such small systems, researchers can more accurately apply theory and in- vestigate how nanoclusters depend on their structure. According to CANELa research- ers, one of the key advances the lab has made to the field is modeling the specific number of gold atoms stabi- lized by a specific number of ligands. Ligand-protected metal nanoclusters are a unique class of nanomaterials that are sometimes referred to as “mag- ic size” nanoclusters because of their high stability when they have specific compositions. Predicting new alloys and previ- ously undiscovered magic sizes is the next step that the field—and the lab— will need to tackle. The lab uses com- putational chemistry methods to mod- el known nanoclusters, but creating a complete database of nanocluster structure, property, and synthesis pa- rameters will be the next step to apply machine learning and create a predic- tion framework. pitt.edu . THERMAL CAMOUFLAGE COATINGS Researchers at University of Cali- fornia, Berkeley discovered a way to im- bed visual decoys into surfaces of ob- jects using delicately engineered thin films of tungsten-doped vanadium di- oxide. Under infrared light, the result- ing structures can be manipulated so onlookers perceive false images on the surface. Infrared light is invisible to the human eye, but can be detected by a range of devices, such as night-vision goggles and thermal-imaging cameras. The researchers’ newcoatings can effec- tively tune target objects into emitting the same infrared radiation as the sur- rounding environment, making them invisible to infrared detection devices. To create the structures, the re- searchers focused on coating objects with tungsten-doped vanadium diox- ide, a substance that at certain tem- peratures can phase shift from an in- sulator to a metal. With judicious engi- neering of the doping profile, the insu- lator-metal phase transition can even out, allowing the substance to emit a constant level of thermal radiation over wide ranges of temperature variations. This state of equilibrium prevents a camera from detecting the true infra- red signals that an object normally emits around room temperature. Ad- ditionally, by manipulating the config- BRIEF Scientists at the University of Vermont, Burlington, invented a new tool that can catch and straighten out molecule-sized tangles of polymers. Calling it a “nanocage,” the scientists explain their tool is composed of molecular edges with special shape-direct- ing hydrogen bonds. It can select out shorter strands of a polymer, leaving longer ones behind, demonstrating that the nanocage can be used to selectively find particular sizes of molecules in a web of material. uvm.edu . Illustration of the University of Pittsburgh’s CANELa lab’s nanocluster modeling. Courtesy of Mpourmpakis and Cowan. Mona Sharafi assisted in constructing this “nanocage,” whichmay help create new types of industrial materials. Courtesy of Joshua Brown/UVM. The letters C-A-L appear cool even when the environment is hot. Using this technology, engineers develop decoys to fool infrared cameras into perceiving a designated temperature rather than the actual temperature of the object. Courtesy of Kechao Tan. uration and composition of tungsten- doped vanadium dioxide on coatings applied to special adhesive tape, re- searchers can create an infrared decoy. This kind of technology could prove useful for military and intelli- gence agencies as they seek to thwart increasingly sophisticated surveillance technologies that pose a threat to na- tional security. It might also incubate future encryption technology, allow- ing information to be safely concealed from unauthorized access. berkeley.edu.