Examination of the site preference in garnet type (X3A2B3O12; X=Y, A/B= Al, Ga, Fe) materials

Abstract

Although many studies of quaternary garnet type oxides have been performed, few studies have investigated quinary garnet type oxides. In this study, quinary (Y3AlxGayFe5-x-yO12) type garnet materials have been studied along with three quaternary garnet-type materials (Y3AlxGa5-xO12, Y3AlxFe5-xO12, and Y3GaxFe5-xO12) using X-ray absorption near-edge spectroscopy (XANES) and powder X-ray diffraction. Fe K-, Ga K-, and Al L2,3- edge XANES spectra were collected and analyzed to study the change in metal site preference depending on composition. The analysis of Fe K-edge XANES spectra indicated that Fe3+ primarily occupied the octahedral site in the Y3AlxFe5-xO12, Y3GaxFe5-xO12, and Y3AlxGayFe5-x-yO12 materials. The Ga K-edge XANES spectra from Y3AlxGa5-xO12 confirmed that Ga3+ has a strong preference for residing in the tetrahedral site. Ga increasingly occupies the tetrahedral site with increasing Al content in Y3AlxGa5-xO12. Al L2,3-edge XANES spectra from Y3AlxGa5-xO12, Y3AlxFe5-xO12, and Y3AlxGayFe5-x-yO12 confirmed the site preference of Al, Ga, and Fe. Rietveld refinement of powder X-ray diffraction patterns from the Y3AlxGa5-xO12 series was also performed and agree with the XANES results.