Fe K-edge X-ray absorption near-edge structure spectroscopy of Allanite from Palawan, Philippines
Th- and U-bearing minerals serve as natural analogs for high-level waste disposal material and provide information on the response of mineral phases to long-term irradiation. Prolonged α-irradiation has the potential to affect the oxidation state of minerals and may alter the minerals' ability to react with radionuclides. In this study, allanite mineral from Ombo, Palawan was analyzed for Fe oxidation states using X-ray absorption near edge spectroscopy at BL5.2 SUT-NANOTEC-SLRI XAS Beamline of SLRI, Thailand. The result of this study was in congruence with and even extended the lower dose end of the results of Malczewski and Grabias (2008) that Fe²⁺ contribution in allanite decreases with absorbed α-dose. The results however, are in contrast with the expected wherein radiation damage process causes reduction of some Fe³⁺ to Fe²⁺ due to radiolysis. Further studies are recommended to explain the contradicting observations.