The effects of oxygen partial pressure (pO2) 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 pO2. 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.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Materials Chemistry