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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 | A P R I L 2 0 2 0 1 4 CONTROLLING SELF- ASSEMBLING COMPOSITES Composites made from self- assembling inorganic materials can be challenging to control but are valued for their unique strength and magnet- ic, thermal, and optical properties. However, the self-forming structures can be highly disordered, leading to defects during large-scale production. Now, researchers at the University of Il- linois, Champaign, and the University of Michigan, Ann Arbor, have developed a templating technique that instills great- er order and gives rise to new 3D struc- tures in a special class of materials, called eutectics, to form new, high-per- formance materials. Eutectic materials contain ele- ments and compounds that have dif- ferent melting and solidification tem- peratures. When combined, however, the composite formed has single melt- ing and freezing temperatures. When a eutectic liquid solidifies, the individual components separate, forming a co- hesive structure—most commonly in a layered form. The fact that eutectic ma- terials self-assemble into composites makes them highly desirable to many modern technologies, ranging from high-performance turbine blades to solder alloys. To demonstrate this process in the lab, the team built templates with tiny posts arranged in hexagonal shapes to control the resolidification of a melt containing silver chloride and potassi- um chloride—a eutectic material that naturally forms layers as it cools. They will explore how these new microstructures influence the physical properties of a wide range of eutectic materials. illinois.edu , umich.edu . PRODUCING AlScN WITH MOCVD In a world’s first, scientists at the Fraunhofer Institute for Applied Solid State Physics IAF, Munich, have manu- factured aluminum scandium nitride (AlScN) via metal-organic chemical va- por deposition (MOCVD). Devices based on AlScN are considered to be the next generation of power electronics. Transistors based on AlScN are promising for various industrial appli- cations, such as data transfer, satel- lite communication, radar systems, or autonomous driving, especially since current devices based on silicon are EMERGING TECHNOLOGY Collins Aerospace Systems, West Palm Beach, Fla., will open a new landing systems facility in Fort Worth, Texas, and expand its carbon brake manufactur- ing facility in Spokane, Wash. The $225 million investment reflects the growth of the company’s Landing Systems business in recent years, driven by increasing demand for its wheels, brakes, and landing gear from commercial, military, and business aviation customers. collinsaerospace.com. BRIEF reaching their physical limit in these ap- plications. High electron mobility tran- sistors, or HEMTs, surpass the possibil- ities of silicon devices by far. The challenging, state-of-the-art production process grows AlScN layers via sputtering. The production of AlScN via MOCVD promises not only the nec- essary quality but also sufficient pro- ductivity for industrial applications. Through heat exposure, distinct mol- ecules are released from the gas and integrated into the crystalline structure of the wafer. The crystal structure can be precisely adjusted by regulating the gas flow, temperature, and pressure. Furthermore, the quick change of gas allows it to grow different material lay- ers on top of each other. After the successful deposition of AlScN in the MOCVD system, the first AlScN layers for transistors were pro- duced. The Fraunhofer scientists aim to reduce sheet resistance and increase mobility and material quality. www. fraunhofer.de/en. Layered material, depicted in this model by orange and blue, transforms into a complex composite material when it freezes around a template, depicted in gray. Courtesy of Paul Braun. Wheel and brake shop floor at Collins Aerospace, Fort Worth. This Fraunhofer research group are the first to develop AlScN via metal organic chemical vapor deposition. Courtesy of Fraunhofer IAF.