May/June_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 | M A Y / J U N E 2 0 1 8 1 5 PUTTING THE SQUEEZE ON GRAPHITE PELLETS Scientists at Rice University, Houston, demonstrated how chemi- cally altered graphene powder can be pressed into a lightweight semiporous solid that retains many of the strong and conductive qualities of graph- ite. Mohamad Kabbani and his team demonstrated that the environmental- ly friendly, scalable process can be per- formed in minutes by grinding chem- ically modified graphene into a pow- der and using a hand-powered press to squeeze the powder into a solid pellet. With their associated chemical func- tionalities, the graphene powders can be pressed into any form. The materi- al holds promise for structural, cata- lytic, electrochemical, and electronic applications. The combination of light weight, high strength, and high con- ductivity is also appealing for applica- tions such as conducting cables and electrodes. rice.edu . BUILDING NEW NANOSCALE ALLOYS A multi-institutional team of sci- entists developed a new technique that can meld ions from up to eight differ- ent elements to form high-entropy al- loyed nanoparticles. The atoms of the elements that make up these parti- cles are distributed evenly through- out and form a single, solid-state crys- talline structure—a feat that had never been achieved with more than three el- ements. The nanoparticles could have broad applications as catalysts. Re- searchers showed that up to eight ele- ments are able to form nanoparticles with a homogeneous crystal structure. “This will really change the way people think about materials that were previ- ously thought to be immiscible,” says Professor Reza Shahbazian-Yassar of the University of Illinois at Chicago. Materials scientists at the Univer- sity of Maryland, College Park, led by Liangbing Hu, produced the high-en- tropy alloys. The team used a two- step process that involves a brief heat shock followed by rapid cooling to get ions of various elements that normally would not form alloys to mix and sta- bilize in crystalline nanoparticles. Sci- entists were able to determine that at the atomic level, their nanoparticles are made of homogeneous mixtures of different combinations of platinum, cobalt, nickel, copper, iron, palladium, and gold. uic.edu , umd.edu . TISSUE PAPER SENSORS HOLD PROMISE FOR HEALTH CARE Engineers at the University of Washington, Seattle, recently turned tissue paper into a new kind of wear- able sensor that can detect a heart- beat, finger motion, eyeball movement, or any other human activity. In their re- search, the scientists used paper simi- lar to toilet tissue. The paper was then doused with carbon nanotube-laced water. Each piece of tissue paper has both horizontal and vertical fibers, so when the paper is torn, the direction of the tear informs the sensor of what has occurred. These small, Band Aid-sized sensors are light, flexible, and inexpen- sive and could be useful in health care, entertainment, and robotics applica- tions. washington.edu . NANOTECHNOLOGY BRIEF Engineers at Rutgers University-New Brunswick, N.J., and Oregon State University, Corvallis, are developing a new method of processing nanomaterials that could lead to faster and cheaper manufacturing of flexible thin film devices: Intense pulsed light sintering uses high-energy light over an area nearly 7000 times larger than a laser to fuse nanomaterials in seconds. newbrunswick.rutgers.edu, oregonstate.edu . Graduate student Jinyuan Zhang demon- strates howwearable sensors can track eye movement. Courtesy of Dennis Wise. Spherical silver nanoparticles and nano- wires after being fused by intense pulses of light. Courtesy of Rajiv Malhotra. Chemically altering graphene powder with carbon, oxygen, and hydrogen enables binding the graphene into a 3D solid under pressure. Courtesy of Ajayan Research Group.