Characterization of brookite and a new corundum-like titania phase synthesized under hydrothermal conditions |
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Authors: | X Bokhimi F Pedraza |
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Institution: | a Institute of Physics, The National University of Mexico (UNAM), A.P. 20-364, 01000 México D.F., Mexicob Molecular Engineering Program, Instituto Mexicano del Petróleo, Eje Central L. Cárdenas 152, A.P. 14-805, 07730 México D.F., Mexico |
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Abstract: | Brookite rich samples were synthesized under hydrothermal conditions by using TiCl3 as precursor. They also contained a new titanium oxide phase that has the same crystalline structure as Ti2O3, and is stable after annealing in air. Samples were characterized with X-ray powder diffraction, transmission electron microscopy and thermogravimetry. Crystalline phases were refined by using the Rietveld method, from which phase concentrations and atomic bond lengths were obtained as a function of sample annealing temperature. Samples contained brookite, anatase, rutile and the new corundum-like phase: Brookite's concentration was larger than 50 wt%, while the one of the corundum-like phase reached 20(6) wt%. The local symmetry and the atomic bond lengths of these two phases depended on the crystallite size; for both, there is a correlation between the evolution of the atomic bond lengths with temperature and their transformation into another phase. The hydrothermal conditions stabilized brookite, anatase, and the corundum-like phase at high temperature: This last phase was stable in air, even at 900°C. |
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Keywords: | Brookite rich samples Corundum-like titania phase synthesis Brookite's stability TiCl3 as titania precursor Synthesis under hydrothermal conditions |
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