Mossbauer study of Al and Cr co-substituted Yttrium iron garnets

The Mossbauer spectra of Y3AlxCrXFe5-2xO12 (x = 0.0 to 0.6) measured at 300 K have been fitted with two sextets in the ferrimagnetic state corresponding to Fe3+ at the octahedral (a) and the tetrahedral (d) sites for x <= 0.6. The isomer shifts (d) and quadrupole splitting (Delta E-Q) indicate the presence of high spin Fe3+ ions in the tetrahedral (d) and octahedral (a) sites, typical of yttrium of yttrium iron garnet structure. Mossbauer results have shown that Al3+, enters a-sites only but Cr3+ enters both a-and d-sites.