title: Self-assembly and crystallization behavior of mesoporous, crystalline HfO2 thin films: a model system for the generation of mesostructured transition-metal oxides.
abstract: Mesoporous thin films of crystalline hafnium oxide were fabricated by evaporation-induced self-assembly in combination with sol-gel processing, followed by a suitable post heat-treatment procedure to initiate the crystallization. A novel type of block-copolymer template was used as structure-directing agent, which generated a distorted cubic arrangement of spherical mesopores, the size of which could be quantified by suitable techniques, such as ellipsometry-porosimetry, small-angle X-ray scattering, and atomic force microscopy. Detailed insights into the nature of the crystallization process of mesostructured hafnium oxide were obtained by temperature-dependent, in situ X-ray scattering experiments. These investigations revealed that crystallization takes place, within the confinement of the mesostructure, as a solid-solid transition from a dehydrated, amorphous form of hafnium oxide. The study suggests that one main benefit of the novel template results from the ability of the polymer to stabilize the mesostructure of amorphous hafnium oxide up to 400-450 degrees C.
authors.affiliation: Max Planck Institute of Colloids and Interfaces, Research Campus Golm, Am Mühlenberg 1, 14424 Potsdam-Golm, Germany.
authors.forename: Torsten
authors.initials: T
authors.lastname: Brezesinski
authors.forename: Bernd
authors.initials: B
authors.lastname: Smarsly
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Iimura
authors.forename: David
authors.initials: D
authors.lastname: Grosso
authors.forename: Cédric
authors.initials: C
authors.lastname: Boissière
authors.forename: Heinz
authors.initials: H
authors.lastname: Amenitsch
authors.forename: Markus
authors.initials: M
authors.lastname: Antonietti
authors.forename: Clément
authors.initials: C
authors.lastname: Sanchez
mesh_terms: D003460:Crystallization; D018360:Crystallography, X-Ray; D005583:Fourier Analysis; D006195:Hafnium / Q000737:chemistry*; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D046529:Microscopy, Electron, Transmission; D008956:Models, Chemical; D036103:Nanotechnology / Q000379:methods*; D009584:Nitrogen / Q000737:chemistry; D010087:Oxides / Q000737:chemistry*; D011108:Polymers; D012542:Scattering, Radiation; D013696:Temperature
chemical_list: D010087:Oxides; D011108:Polymers; D009584:Nitrogen; D006195:Hafnium