X-ray absorption spectroscopy study on yttrium iron garnet (Y3Fe5O12) nanocrystalline powders synthesized using egg white-based sol-gel route

Nanocrystalline powders of yttrium iron garnet (Y3Fe5O12) were synthesized using egg white-based sol-gel method. Garnet samples were obtained after calcination in air at 700, 800, 900, and 1000 degrees C for 3 h. Polycrystalline phases occurring in samples are investigated using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Magnetic properties of the samples were measured using the vibrating sample magnetometer (VSM). X-ray absorption spectroscopy (XAS) including X-ray absorption near edge structure (XANES) and X-ray absorption fine structure (EXAFS) was employed in order to reveal the oxidation state and local structure around Fe atoms in the prepared samples. From XANES study we found that Fe ions in all samples show the oxidation states of 3+ in the tetrahedral and octahedral sites in the structure. In addition, the Fe-O distances (1st shell) in all garnet samples keep the same value, 1.80 +/- 0.02 angstrom. In contrast, the Fe-Fe and Fe-Y distances are significantly different when the samples were calcined at different temperatures. (C) 2014 Elsevier B.V. All rights reserved.