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

Perovskite powder Gd0.5Sr0.5FeO3-y was studied by X-ray diffraction, Moessbauer 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, a0=5.531 A, b0=5.608 A and c0=7.724 A. Moessbauer 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, TN, 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