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specific-surface-area--ssa
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Semiconductor TiO2-Ga2O3 thin film gas sensors derived from particulate sol-gel route
, Article Acta Materialia ; Volume 55, Issue 13 , 2007 , Pages 4455-4466 ; 13596454 (ISSN) ; Fray, D. J ; Sharif University of Technology
2007
Abstract
Nanostructured and mesoporous TiO2-Ga2O3 thin films with various Ti:Ga atomic ratios were prepared by a new straightforward particulate sol-gel route. Titanium isopropoxide and gallium (III) nitrate hydrate were used as precursors, and hydroxypropyl cellulose (HPC) was used as a polymeric fugitive agent (PFA) in order to increase the specific surface area (SSA). XRD and TEM analysis of the powders revealed that the Ga2O3 formed from the nitrate precursor retarded anatase-to-rutile transformation, crystallization and crystal growth. The average crystallite size of pure TiO2 powder annealed at 600-1000 °C were in the range 4-10 nm; the values that could be decreased to 2-6 nm for TiO2-Ga2O3...
Synthesis of high surface area nanocrystalline anatase-TiO2 powders derived from particulate sol-gel route by tailoring processing parameters
, Article Journal of Sol-Gel Science and Technology ; Volume 40, Issue 1 , 2006 , Pages 15-23 ; 09280707 (ISSN) ; Cordero Cabrera, M. C ; Ghorbani, M ; Fray, D.J ; Sharif University of Technology
2006
Abstract
Stabilised titania sols were prepared using an additive free particulate sol-gel route, via electrostatic stabilisation mechanism, with various processing parameters. Peptisation temperature, 50°C and 70°C, and TiO2 concentration, 0.1, 0.2 and 0.4 molar, were chosen as processing parameters during sol preparation. Results from TiO2 particle size and zeta potential of sols revealed that the smallest titania hydrodynamic diameter (13 nm) and the highest zeta potential (47.7 mV) were obtained for the sol produced at the lower peptisation temperature of 50°C and lower TiO 2 concentration of 0.1 M. On the other hand, between the sols prepared at 70°C, smaller titania particles (20 nm) and higher...
Preparation and characterisation of nanostructural TiO2-Er 2O3 binary oxides with high surface area derived from particulate sol-gel route
, Article Materials Science and Technology ; Volume 22, Issue 8 , 2006 , Pages 965-974 ; 02670836 (ISSN) ; Ghorbani, M ; Fray, D. J ; Sharif University of Technology
2006
Abstract
Nanostructured and nanoporous TiO2-Er2O3 films and powders with various TiO2 : Er2O3 molar ratios and high specific surface area (SSA) have been prepared by a new straightforward particulate sol-gel route. X-ray diffraction and Fourier transform infrared spectroscopy revealed that erbium oxide formed in the range 50-100 mol.-%Er2O3, whereas erbium dititanate formed in the range 25-100 mol.-%Er2O3. Oxygen deficient titania phases (TiO2-x), such as Ti7O13 and Ti 2O3, were observed for TiO2:Er 2O3=25:75 (molar ratio) system annealed at 800°C. It was observed that Er2O3 retarded anatase to rutile transformation. Furthermore, TEM analysis also showed that Er2O 3 hindered the crystallisation and...