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Self‐Assembly and Crystallization Behavior of Mesoporous, Crystalline HfO 2 Thin Films: A Model System for the Generation of Mesostructured Transition‐Metal Oxides
Author(s) -
Brezesinski Torsten,
Smarsly Bernd,
Iimura Kenichi,
Grosso David,
Boissière Cédric,
Amenitsch Heinz,
Antonietti Markus,
Sanchez Clément
Publication year - 2005
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.200500024
Subject(s) - materials science , crystallization , amorphous solid , mesoporous material , chemical engineering , hafnium , evaporation , polymer , oxide , thin film , ellipsometry , nanotechnology , crystallography , composite material , organic chemistry , zirconium , metallurgy , chemistry , physics , engineering , thermodynamics , catalysis
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 °C.