Synthesis, structure, and magnetic properties of SrMn1−xGaxO3−δ (x=0–0.5) perovskites

We report the synthesis of SrMn1−xGaxO3−δ perovskite compounds and describe the dependence of their phase stability and structural and physical properties over extended cation and oxygen composition ranges. Using special synthesis techniques derived from thermogravimetric measurements, we have extended the solubility limit of random substitution of Ga3+ for Mn in the cubic perovskite phase to image. In the cubic perovskite phase the maximum oxygen content is close to 3−x/2, which corresponds to 100% Mn4+. Maximally oxygenated solid solution compounds are found to order antiferromagnetically for image, with the transition temperature linearly decreasing as Ga content increases. Increasing the Ga content introduces frustration into the magnetic system and a spin-glass state is observed for SrMn0.5Ga0.5O2.67(3) below 12 K. These properties are markedly different from the long-range antiferromagnetic order below 180 K observed for the layer-ordered compound Sr2MnGaO5.50 with nominally identical chemical composition.