Solid state syntheses of 12SrO·7Al2O3 and formation of high density oxygen radical anions, O- and O 2-

Katsuro Hayashi, Naoto Ueda, Satoru Matsuishi, Masahiro Hirano, Toshio Kamiya, Hideo Hosono

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

A new synthetic route via a solid-state reaction, the crystal structure of 12SrO·Al2O3 (S12A7) incorporated with OH- ions, and the formation of oxygen radical anions in S12A7 have been examined. Investigations using X-ray powder diffraction and thermogravimetric and evolved gas combined analyses demonstrate that homogenization promoted by molten Sr(OH)2 hydrates and the presence of Sr-hydrogarnet precursors play crucial roles in the formation of S12A7. Rietveld analyses confirm the lattice framework of S12A7 has a structure identical to that of the nanoporous crystal 12CaO·7Al2O3 (C 12A7, a mayenite structure) and demonstrate that two Sr2+ ions (pole Sr2+ ions) on the S4 axis of a cage displace toward the cage center owing to the accommodation of an OH - ion. An electron paramagnetic resonance study demonstrates that oxygen radical anions, O2- and O-, are generated in the cages with concentrations on the order of 1020 cm-3 each by oxygen annealing. From the g-values observed at 77 K, the oxygen radical anions are interpreted as being sandwiched between the two pole Sr2+ ions rather than adsorbed on one side.

Original languageEnglish
Pages (from-to)5987-5996
Number of pages10
JournalChemistry of Materials
Volume20
Issue number19
DOIs
Publication statusPublished - Oct 14 2008
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

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