Evolution of nanocrystallinity in periodic mesoporous anatase thin films.
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.
Choi
Sung Yeun
SY
Materials Chemistry Research Group, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, Canada.
Mamak
Marc
M
Speakman
Scott
S
Chopra
Naveen
N
Ozin
Geoffrey A
GA
D016880:Anisotropy; D003460:Crystallization; D004058:Diffusion; D007700:Kinetics; D050866:Liquid Crystals / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology / Q000295:instrumentation / Q000379:methods*; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014025:Titanium / Q000737:chemistry; D014961:X-Ray Diffraction
C009495:titanium dioxide; D014025:Titanium