b'Look-AheadNANOMATERIALS SHAPE UPF or metal nanomaterials to de- magnesium. More economical pro- they did so in an orderly fashion. liver on their promise to energyduction techniques usually involveThe researchers learned they could and electronics, they need to liter- vapor phase approaches to create apredict this based on the type of ally shape up. cloud of particles condensing frommetal and how and where they ap-To provide reliable mechanicalthe vapor. These methods sufferplied the magnetic fields.and electrical properties, nano- from a lack of control. Ironandnickelnanoparticles materials must have consistent,Reza Abbaschian, distinguishedformed stringlike aggregates while predictable shapes and surfaces,professorofmechanicalengi- copper nanoparticles formed glob-aswellasscalableproductionneering, andMichael Zachariah,ular clusters. When deposited on a carbon film, iron and nickel aggregates gave a porous surface to the film, and carbon aggre-gates resulted in a more compact, solid surface. The qualities of the ma-terials on the carbon film mirrored at larger scale the properties of each type of nanoparticle.Because the field can be thought of as an add-on, this method could be applied to any vapor phase nanoparticle gen-eration source in which the structure is impor-tant, such as fillers used in polymer composites Abbaschian, Zachariah, et al. for magnetic shielding, or Shown are the stringlike particles formed by iron and nickel and the more globular clusters formed by copper. to improve electrical or mechanical properties.techniques. Engineers at Universitydistinguished professor of chemi- This field-directed approach en-of California, Riverside are solvingcal and environmental engineering,ables one to manipulate the as-this problem by vaporizing metals inat Riversides Marlan and Rosemarysembly process and change the ar-a magnetic field to direct the reas- BournsCollegeofEngineeringchitecture of the resulting particles sembly of metal atoms into predict- joined forces to create nanomate- from high-fractal-dimension objects able shapes. The research ispub- rials from iron, copper and nickel into lower-dimension stringlike struc-lishedin The Journal of Physicala gas phase. The professors placedtures, Zachariah said. The field Chemistry Letters. solid metal in a powerful electro- strength can be used to manipulate Nanomaterials are made of par- magnetic levitation coil to heat thethe extent of this arrangement.ticles measuring 1 to 100 nanome- metal beyond its melting point, va- He and Abbaschian were joined ters and typically are created in aporizing it. The metal droplets levi- in the research by Pankaj Ghildiyal, liquid matrix, which is expensivetated in the gas within the coil andPrithwish Biswas, Steven Herrera, for bulk production applicationsmoved in directions determined byGeorge W. Mulholland and Yong and in many cases cannot maketheir inherent reactions to magneticYang.CTEpure metals, such as aluminum orforces. When the droplets bonded, Holly Oberctemag.com/cteguide.com49LookAhead.indd 49 8/18/21 10:20 AM'