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Evolution of Nanocrystallinity in Periodic Mesoporous Anatase Thin Films
Author(s) -
Choi Sung Yeun,
Mamak Marc,
Speakman Scott,
Chopra Naveen,
Ozin Geoffrey A.
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.200400038
Subject(s) - anatase , nanocrystalline material , materials science , mesoporous material , amorphous solid , transmission electron microscopy , nanocrystal , chemical engineering , scanning electron microscope , nanotechnology , phase transition , high resolution transmission electron microscopy , thin film , crystallography , composite material , chemistry , condensed matter physics , organic chemistry , physics , photocatalysis , engineering , catalysis
Herein we report the first kinetic study of the intrachannel wall phase‐transition of amorphous titania to nanocrystalline anatase for periodic mesoporous titania thin films, monitored by time‐resolved in situ high‐temperature X‐ray diffraction. Structural transformations associated with the phase transition are further probed by high‐resolution scanning electron microscopy and transmission electron microscopy. The model found to be most consistent with the kinetic data involves 1D diffusion‐controlled growth of nanocrystalline anatase within the spatial confines of the channel walls of the mesostructure. The observation of anisotropic, rod‐shaped anatase nanocrystals preferentially aligned along the channel axis implies that the framework of the liquid‐crystal‐templated mesostructure guides the crystal growth.