Nanocrystalline microstructures

Various microstructures and configurations are possible for useful solid materials, including bulk single crystals and epitaxial layers, polycrystalline articles or thin films with controlled grain size (including micro- and nanocrystalline... 

Ivanov, V.K., Shaporev, A.S., Sharikov, F.Y. and Baranchikov, A.Y. (2007) Hydrothermal and microwave-assisted synthesis of nanocrystalline ZnO photocatalysts. Superlattices and Microstructures, 42, 421-424. 

Carbone, C., Di Benedetto, F., Marescotti, P., Martinelu, A., Sangregorio, C., Cipriani, C., Lucchetti, G., Romanelli, M. 2005. Genetic evolution of nanocrystalline Fe oxide and oxyhydroxide assemblages from the Libiola Mine (eastern Liguria, Italy) structural and microstructural investigations. European Journal of Mineralogy, 17, 785-795. 

Zr-based AB2 Laves phase alloys consist of cast polycrystalline and nanocrystalline structures. The nanocrystalline microstructure could be obtained for quenching the melt-spun alloys after annealing151. Figure 1 shows SEM Micrographs of the cast Polycrystalline ABi Alloys. Microstructures of AB2-1 alloys consist of cubic C15 Laves phase, hexagonal C14 Laves phase and of AB2-4 is only Cl5. The white one of non Laves in AB2-I and AB2-4 is the phase Zr9Nil 1 and Zr7NilO respectively. 

O. Friedrichs, J.C. Sdnchez-Ldpez, C. Lopez-Cartes, M. Dornheim, T. Klassen, R. Bormann, A. Femdndez, Chemical and microstructural study of the oxygen passivation behaviour of nanocrystalline Mg and MgH, Appl. Surf. Sci. 252 (2006) 2334-2345. 

The results of several research groups clearly demonstrate that partial replacement of Na by Li is feasible and thus higher hydrogen storage capacities are accessible for the hexahydride phase. The nanocrystalline microstructure ensures reversibility with respect to the decomposition/recombination reaction during the hydrogen desorp-tion/absorption reaction. 

Electrodes can be prepared by electrostatic spray deposition of nanocrystalline cubic Pt dense thin films on YSZ, using Pt(acac)2 as precursor. Investigation of the catalytic behavior of the deposited Pt as a function of the microstructural properties is currently in progress. 

Sol-gel processes are also suitable for lanthanide oxide formation, as could be shown by the use of Tb(acac)3 and Dy(OBu- )3 in acetylacetone" . Tb203 crack- and pine-hole-free, dense and smooth microstructured buffer layers were produced on nickel tapes by a reel-to-reel continuous sol-gel process. The authors report that the film properties can be strongly influenced by solution components, temperature, time and atmosphere. Nanocrystalline mesoporous dysprosium oxide Dy203 with narrow monomodal pore size distribution can be approached by a combined sol-gel process with a surfactant-assisted templating technique . The spherical Dy203 nanoparticles were formed with aggregations. 

M. L. Ciurea, V. lancu, V. S. Teodorescu, L. C. Nistor, and M. G. Blanchin, Microstructural aspects related to carrier transport properties of nanocrystalline porous silicon films, J. Electrochem. Soc. 146(9), 3516, 1999. 

In this section, attention will be focused on the preparation and characterization of nanocrystals, paying particular attention to methods that probe the microstructure and the atomic transport. It should be noted that an excellent review of the chemistry of nanocrystalline oxides, together with coverage of many of the characterization methods employed, is available [137]. 

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