Abstract
This paper presents an experimental and theoretical study on the oxidation states and occupation sites of Fe and Cu ions in the Y_3Fe_(5-x)Cu_xO_(12), (0.00 ≤ x ≤ 0.05) compound synthesized via sol gel method. Transmission electron microscopy images showed agglomerated coral-shaped particles, while selected area electron diffraction analysis confrmed the formation of YIG cubic structure, since the bright points correspond to the (004), (123), (024), (224), (022), and (112) YIG family planes. Fourier transform infrared and Raman spectroscopies testifed the YIG crystal structure formation and suggest that the Fe by Cu replacement occurs in the octahedral sites. The cation distribution and reticular energy were estimated theoretically, revealing that the more probable valence state combination corresponds to Cu~+-Fe~(2+) doped YIG confg-uration. The experimental study by X-ray Photoelectron Spectroscopy certifed the elements valence states and confrmed that Y, Fe and Cu are mainly in the Y~(3+), Fe~(3+), Fe~(2+) and Cu~+ oxidation states. The oxygen vacancies formation was also identifed through the deconvolution of XPS spectra for the oxygen region. Finally, the dopant occupation probability per site as function of dopant concentration per unit formula was calculated using a phenomenological model and suggested that Cu+ and Fe~(2+) cations prefer to occupy the octahedral sites in the YIG crystal structure.
NSTL
Elsevier