title: Influence of surface diffusion on the formation of hollow nanostructures induced by the Kirkendall effect: the basic concept.
abstract: The Kirkendall effect has been widely applied for fabrication of nanoscale hollow structures, which involves an unbalanced counterdiffusion through a reaction interface. Conventional treatment of this process only considers the bulk diffusion of growth species and vacancies. In this letter, a conceptual extension is proposed: the development of the hollow interior undergoes two main stages. The initial stage is the generation of small Kirkendall voids intersecting the compound interface via a bulk diffusion process; the second stage is dominated by surface diffusion of the core material (viz., the fast-diffusing species) along the pore surface. This concept applies to spherical as well as cylindrical nanometer and microscale structures, and even to macroscopic bilayers. As supporting evidence, we show the results of a spinel-forming solid-state reaction of core-shell nanowires, as well as of a planar bilayer of ZnO-Al2O3 to illustrate the influence of surface diffusion on the morphology evolution.
authors: Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany.
authors: Hong Jin
authors: HJ
authors: Fan
authors: Mato
authors: M
authors: Knez
authors: Roland
authors: R
authors: Scholz
authors: Dietrich
authors: D
authors: Hesse
authors: Kornelius
authors: K
authors: Nielsch
authors: Margit
authors: M
authors: Zacharias
authors: Ulrich
authors: U
authors: Gösele
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry*; D003198:Computer Simulation; D003460:Crystallization / Q000379:methods*; D004058:Diffusion; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D036103:Nanotechnology / Q000379:methods; D010316:Particle Size; D013499:Surface Properties; D015034:Zinc Oxide / Q000737:chemistry*
chemical_list: D046911:Macromolecular Substances; D000537:Aluminum Oxide; D015034:Zinc Oxide