Structure and Raman spectra of layered titanium oxides
- Kyung Hee Univ. (Korea, Republic of)
The Raman spectra of layered titanium oxides, NaLnTiO{sub 4}, Na{sub 2}Ln{sub 2}Ti{sub 3}O{sub 10}, HLnTiO{sub 4}, and HLnTiO{sub 4}{center_dot}xH{sub 2}O (Ln = lanthanides), were investigated. The assignment of the Raman bands was based on the structural data. The characteristic major band around 900 cm{sup -1} of parent sodium compounds, which is assigned to the symmetric stretching mode of a short Ti-O bond, was not observed for proton-exchanged derivatives but instead a broad weak band around 820 cm{sup -1} appeared. Such a change is proposed to result from the replacement of an ionic Ti-O{sup -}Na{sup +} bond by a covalent Ti-O-H bond. The difference in Bronsted acidity between titanium oxides and niobium oxides with similar structure could be explained by comparison of their Raman spectra before and after proton exchanges. A structural rearrangement by the intercalation of a water molecule into a proton layer gave two bands around 770 and 900 cm{sup -1}, which were assigned to two types of terminal Ti-O bonds with different bond orders. In addition, several characteristic modes of layered-type titanium oxides were systematically compared and assigned.
- OSTI ID:
- 543092
- Journal Information:
- Journal of Solid State Chemistry, Vol. 130, Issue 1; Other Information: PBD: Apr 1997
- Country of Publication:
- United States
- Language:
- English
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