Inorganic Electrides Formed by Alkali Metal Addition to Pure Silica Zeolites

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• 作者：Daryl P. Wernette ; Andrew S. Ichimura ; Stephanie A. Urbin ; and James L. Dye
• 刊名：Chemistry of Materials
• 出版年：2003
• 出版时间：April 8, 2003
• 年：2003
• 卷：15
• 期：7
• 页码：1441 - 1448
• 全文大小：135K
• 年卷期：v.15,no.7(April 8, 2003)
• ISSN：1520-5002

文摘

Up to 4 Cs or Rb atoms per 32 Si atoms can be incorporated into the channels of theall-silica (SiO₂) zeolites ITQ-4 and beta with effective oxidation states of zero. The opticalproperties and ²⁹Si MAS NMR spectra suggest partial or complete ionization within thechannels to yield M⁺ ions and relatively free electrons. This view is supported by a publishedstructural model (Petkov, V.; Billinge, S. I.; Vogt, T.; Ichimura, A. S.; Dye, J. L. Phys. Rev.Lett. 2002, 89, 075502) based on pair distribution functions for Cs in ITQ-4. As with solutionsof alkali metals in ammonia, however, the trapped electrons in this inorganic electrideinteract with the cations, and spin-pairing between adjacent electrons also occurs. The crystalmorphology is unaffected by the inclusion of alkali metals. Structural distortions that reduceor eliminate long-range order are completely reversed upon oxidation and removal of themetal. At higher temperatures, Na and K can also be incorporated, but the optical spectraindicate that either substantial ionization does not occur or the released electrons reactreversibly with the silica to form strongly reducing species.