Fe-O atoms are arranged in alternating tetrahedral and octahedral planes that can be distinguished looking at the fine structure of the O K-edge at 532 eV. Hybridization between the O and Fe orbitals is different depending on the way the atoms are arranged, and changes can be seen in the O K-edge at 532 eV in the EELS spectrum.
Methods
probe corrected ARM 200F TEM/STEM microscope
C-FEG emission gun
GIF Quantum® ER system
voltage: 200 kV
data taken in STEM mode
EELS low-loss spectrum (0–500 eV) exposure time: 0.2 ms
EELS core-loss spectrum (250–750 eV) exposure time: 50 ms
beam current: 70 pA
total exposure time: <2 min