Abstract
The cubic perovskite solid solution Sr
2
FeSnO
5.71
, which contains both Fe
3+
and Fe
4+
cations, has been shown to be a spin-glass by a combination of magnetic susceptibility with
57
Fe and 119Sn Mössbauer 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 Mössbauer magnetic hyperfine splitting with rise in temperature is complete by 26 ± 2 K. The transferred hyperfine nteractions in the
119
Sn resonance at 4.2 K give evidence to support the existence of randomly oriented spin moments. The composition Sr
2
FeSnO
5.50
which can be obtained by heating
in vacuo
contains only Fe
3+
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 √2a
p
×√2a
p
× 2a
p
, where a
p
is the cubic perovskite lattice parameter, and the
119
Sn spectrum at 4.2 K shows that there is a substantial but unidentified ordering of the tin and iron cations.