SPIN-GLASS AND BEHAVIOR IN SR2FESNO6-Y STUDIED BY MOSSBAUER-SPECTROSCOPY

The cubic perovskite solid solution Sr2FeSnO5.7, which contains both Fe3+ and Fe4+ cations, has been shown to be a spin-glass by a combination of magnetic susceptibility with Fe-57 and Sn-119 Mossbauer spectroscopic measurements. The zero-field-cooled and field-cooled magnetic susceptibility diverge below a temperature of 15+/-2 K, and a relaxational collapse of the Mossbauer magnetic hyperfine splitting with rise in temperature is complete by 26+/-2 K. The transferred hyperfine interactions in the Sn-119 resonance at 4.2 K give evidence to support the existence of randomly oriented spin moments. The composition Sr2FeSnO5.50 which can be obtained by heating in vacuo contains only Fe3+ cations and shows magnetic relaxation in a similar temperature region. However, electron diffraction measurements give evidence for short-range cation ordering to produce a supercell of root 2a(p) x root 2a(p) x 2a(p), where a(p) is the cubic perovskite lattice parameter, and the Sn-119 spectrum at 4.2 K shows that there is a substantial but unidentified ordering of the tin and iron cations.