title: Voids and yolk-shells from crystals that coat particles.
abstract: We investigate curvature-driven core-shell morphology that emerges when polycrystalline shells of ZIF-8 (zeolitic imidazolate framework coordination polymer) grow on colloid-sized particles. In early growth stages, the shell is continuous, but it transforms to yolk-shell, with neither sacrificial template nor core etching, because of geometrical frustration. A design rule is developed regarding how local surface curvature matters. Comparing shells grown on cubic, rod-like, and peanut-shaped hematite core particles, we validate the argument.
authors.affiliation: Department of Chemistry, ‡Department of Materials Science and Engineering, and §Department of Physics, University of Illinois , Urbana, Illinois 61801, United States.
authors.forename: Melinda
authors.initials: M
authors.lastname: Sindoro
authors.forename: Steve
authors.initials: S
authors.lastname: Granick