Maximum Incorporation of Oxygen Radicals, O- and O2 -, into 12CaO·7Al2O3 with a Nanoporous Structure

The effects of oxygen partial pressure (p O 2 ) up to 400 atm on the generation of active oxygen radicals in 12CaO·7Al2O3 (C12A7) was examined using a hot isostatic pressing technique. Concentrations of superoxide (O2 -) and oxygen anion radicals (O-), which were analyzed from a combination of elect...

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Bibliographic Details
Published in:Chemistry of materials 2003-05, Vol.15 (9), p.1851-1854
Main Authors: Hayashi, Katsuro, Matsuishi, Satoru, Ueda, Naoto, Hirano, Masahiro, Hosono, Hideo
Format: Article
Language:English
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Summary:The effects of oxygen partial pressure (p O 2 ) up to 400 atm on the generation of active oxygen radicals in 12CaO·7Al2O3 (C12A7) was examined using a hot isostatic pressing technique. Concentrations of superoxide (O2 -) and oxygen anion radicals (O-), which were analyzed from a combination of electron paramagnetic spin resonance (EPR) and Raman spectroscopy, increased with p O 2 . The total concentration of the radicals reached 1.7 × 1021 cm3, which is comparable to the theoretical maximum, confirmed that dominant radical incorporation process is O2- (cage) + O2 (atmosphere) → O- (cage) + O2 - (cage). The radical incorporated C12A7 has a large magnetic susceptibility that obeys Curie's law down to 2.5 K without magnetic ordering, although a weak exchange interaction was suggested by the line narrowing of the EPR signal.
ISSN:0897-4756
1520-5002
DOI:10.1021/cm020959g