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Materials Research Laboratory
Materials Science and Engineering: Ceramic Synthesis and Processing
- Electronic and Energetic Properties of Materials
- Structure, Topology, and Properties of Metallic Nanoclusters
- Colloidal Assembly of Mesoscale Periodic Structures: II. Templates for Photonic Band Gap Materials
^ Electronic and Energetic Properties of Materials
D. D. Johnson*
U.S. Department of Energy, DE-FG02-91ER45439
(In cooperation with the Frederick Seitz Materials Research Laboratory and Oak Ridge National Laboratory)
Within a Green's function formalism, electronic density-functional theory (DFT) techniques are used to investigate disordered, partially ordered, and fully ordered phases of multicomponent alloy systems (such as substitutional alloys, ferroelectrics, high-Tc superconductors, and battery and catalysis materials). The underlying electronic origin of various materials properties (electronic, magnetic, thermodynamic, and elastic) are then determined. Additional schemes are being developed to investigate such larger-scale phenomena as microstructure and kinetics, which are ultimately based on such DFT results, thus allowing a connection of length scales, micro- to macroscale.
^ Structure, Topology, and Properties of Metallic Nanoclusters
D. D. Johnson*
National Science Foundation, DMR 99-76550
(In cooperation with the Frederick Seitz Materials Research Laboratory)
Metallic and bi-metallic nanoclusters play an important role in fuel cell and catalysis applications. Researchers plan joint DPT-based and empirical-based simulations to predict structure, topology, and electronic properties of such clusters, as well as to explain ongoing experiments in these materials by Nuzzo et al., and their apparent self-organization.
^ Colloidal Assembly of Mesoscale Periodic Structures: II. Templates for Photonic Band Gap Materials
J. A. Lewis,* G. Gratson, S. Pruzinsky, P. V. Braun
National Science Foundation Division of Materials Research
Colloidal assembly of mesoscale periodic structures is being carried out via self-assembly of binary colloidal mixtures. This collaborative effort between the Lewis and Braun groups involves colloidal crystallization on patterned substrates followed by infiltration with a high refractive index material. Using confocal scanning laser microscopy, researchers aim to study colloidal crystallization on smooth and patterned substrates. The effects of colloid volume fraction and size, interparticle forces, and nanoparticle species on crystallization will be probed. The ultimate aim is to fabricate colloidal arrays with controlled periodicity and defect states required for photonic band gap (PBG) applications.
