Anisotropic FCC Metal Nanostructures by Kinetically Controlled Synthesis

J Wang, Y Xiong, B Lim, Y Xia, MJ Kim
2009 Microscopy and Microanalysis  
Shape control of nanostructures has received considerable attention because the properties of nanostructures depend on their size, shape, composition, crystallinity, and structure. For facecentered cubic (fcc) metals, there is no intrinsic driving force for the growth of anisotropic structures when the seeds are surrounded by an isotropic medium. Thermodynamically, fcc metal atoms are expected to nucleate and grow into cuboctahedrons (with a nearly spherical shape) enclosed by a mix of {111}
more » ... {100} facets to minimize the total surface energy. An fcc metal can only be forced to grow into anisotropic nanostructures through kinetic control, although cubic symmetry is broken in this process. This paper describes a simple and versatile method for growing highly anisotropic nanostructures of fcc metals as well as HRTEM characterization of single crystal anisotropic fcc metal nanostructures. Anisotropic fcc metal nanostructures were synthesized by a solution-phase method [1]. Structure characterization was performed in a JEOL 2100F field emission transmission electron microscope equipped with a Gatan Enfina 1000 spectrometer and EDAX energy dispersive x-ray spectrometer. Under Scherzer defocus, the JEOL 2100F with a UHR pole piece has a point resolution of 1.9 Å. For fcc metals (such as Pd, Ag) viewed along <100> or <111> orientation, some of the interplanar distances are less than 1.9 Å. In order to resolve this, HRTEM images need to be taken at Lichte defocus which maximizes the information limit of the microscope to 1.0 Å [2].
doi:10.1017/s1431927609093258 fatcat:zykedfdonndmdgfimcl3sdvxve