Spectroscopic Studies of Disorder in the Microporous Titanosilicate ETS-10
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- 作者：Peter D. Southon and Russell F. Howe
- 刊名：Chemistry of Materials
- 出版年：2002
- 出版时间：October 2002
- 年：2002
- 卷：14
- 期：10
- 页码：4209 - 4218
- 全文大小：370K
- 年卷期：v.14,no.10(October 2002)
- ISSN：1520-5002
文摘
The microporous titanosilicate ETS-10 is a potential photocatalytic material with adisordered crystal structure. The disordered stacking of repeat units in the structure givesrise to defects that strongly influence the reactivity. This paper describes the spectroscopicstudy of a series of ETS-10 samples containing different levels of defects. All samples arewell crystalline by X-ray powder diffraction, but they show significant variations in otherspectroscopic properties that are sensitive to short-range order. Raman spectroscopy wasparticularly sensitive to disorder, and the 724 cm-1 stretching mode of the -Ti-O-Ti-chains broadened and shifted with increasing disorder through the series. Changes in theUV absorbance spectrum also indicated disruptions of the delocalized charge-transfertransitions along the chains. We propose that stacking defects interrupt the -Ti-O-Ti-chains and that differences in the relative nucleation and growth rates lead to differentconcentrations of these defects. Hydroxyl groups associated with defect sites were observedby FTIR and solid-state cross-polarization 1H-29Si NMR. Disorder is also correlated withthe occurrence of faulting in the crystal morphology. No new cation exchange sites associatedwith the defects were observed by 3Q 23Na NMR.