Temperature-dependent electron acceptor properties of zeolite Y: A combined Mössbauer and positron lifetime spectroscopy study

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Abstract

An unusual temperature dependence of the concentration of nucleogenic Fe2+ ions, formed after the 57Co(EC)57Fe nuclear transition, has been observed by Mössbauer spectroscopy in zeolite Y. The observed temperature dependence could be explained by the assumption of an electron acceptor process that changes with the temperature. To prove this assumption we have applied positron lifetime spectroscopy, as in zeolites the formation of positronium atoms takes place similarly to the formation of Fe2+ after the decay of 57Co nuclids. In both processes the surrounding zeolite matrix plays the role of a competing electron acceptor. The results proved that both multicharged iron ions and positrons do compete for electrons with the zeolite matrix. The zeolite matrix behaves as it has two states having different electron acceptor properties. The density of these states varies with the temperature and the activation energy for the transformation is about 2.4 kJ/mol, as proved by the two methods independently.

Original languageEnglish
Pages (from-to)266-268
Number of pages3
JournalMaterials Science Forum
Volume363-365
Publication statusPublished - Jun 2 2001
Event12th International Conference on Positron Annihilation - Munchen, Germany
Duration: Aug 6 2000Aug 12 2000

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Keywords

  • Competing acceptors
  • Ortho-positronium states
  • Zeolite

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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