The effect of manganese oxidation state on antiferromagnetic order in SrMn 1−x Sb x O 3 (0 < x < 0.5) perovskite solid solutions

Abstract

The mixed-valence manganese (Mn 3+ /Mn 4+ ) solid solution, SrMn 1−x Sb x O 3 , was prepared for the first time. Two ranges of solid solutions were found: (1) SrMn 1−x Sb x O 3 (0.025 ≤ x ≤ 0.09) with monoclinically distorted 6H-SrMnO 3 polytype (sp. gr. C/2c) and (2) SrMn 1−x Sb x O 3 (0.17 ≤ x ≤ 0.50) with a tetragonal unit cell (sp. gr. I4/mcm). Crystal structure refinement using X-ray and neutron powder diffraction data showed that the structure of the monoclinic solid solution consists of corner-sharing octahedra around sites occupied by manganese and antimony ions and face-sharing octahedra around sites occupied by manganese ions only, while the tetragonal solid solution has a random distribution of B-site cations. The presence of long-range antiferromagnetic order with a Néel temperature of about 148 K for SrMn 0.80 Sb 0.20 O 3 and about 280 K for SrMn 0.925 Sb 0.075 O 3 was found from the results of DC and AC susceptibility and neutron diffraction experiments at 5 K and 80 K.