Local structure examination of mineral-derived Fe₂O₃ powder by Fe K-edge EXAFS and XANES

Fe K-edge XANES (X-ray Absorption Near Edge Structure) and EXAFS (Extended X-ray Absorption Fine Structure) spectra have been used to investigate the local structures of hematite (Fe₂O₃) powders which were synthesized from local iron stone. The formation of hematite with various calcination temperature (500, 650, 800) °C was observed from XRD data of each powder, and Fe K-edge EXAFS and XANES were performed to sample with calcination temperature 800 °C. The XANES spectra confirmed the oxidation state of the powders. The energy position of the first pre-edge peak at (7113.5 ± 0.5) eV confirm Fe³⁺. The absorption edges of Fe₂O₃ powders was 7123.41 eV. The first EXAFS data analysis showed that Fe₂O₃ powder exhibited nearest-neighbor distances R_Fe-O = 1.56449 Å and R_Fe-Fe = 3.01449 Å. The XRD lattice parameter values for the sample is in a fair agreement with the nearest-neighbor distances according to the EXAFS data. (paper)