Mossbauer studies of perovskite Gd0.5Sr0.5FeO3-y

Perovskite powder Gd0.5Sr0.5FeO3-y was studied by X-ray diffraction, Mossbauer spectroscopy, vibrating samples magnetometry, and Mohr's salt analysis. Gd0.5Sr0.5FeO3-y was synthesized by using the solid-solid reaction method. The crystal structure was found to be orthorhombic with lattice parameters, a(0)=5.531 Angstrom, b(0)=5.608 Angstrom and c(0)=7.724 Angstrom. Mossbauer spectra of Gd0.5Sr0.5FeO3-y have been taken at various temperatures ranging from 4.2 to 600 K. The spectrum pattern at 4.2 K consisted of four sets of six Lorentzians, and the magnetic hyperfine fields are found to be 275, 486, 514 and 540 kOe. The Neel temperature, T-N, was found to be 478 K. Mohr's salt analysis for Gd0.5Sr0.5FeO3-y demonstrated the existence of the mixed valence states, Fe3+ (73 %) and Fe4+ (27 %), and y=0.11 at room temperature. It is notable that Fe5+ was created at 4.2 K. The magnetic susceptibility show that the superexchange interaction was antiferromagnetic.