Effects of oxygen content on Bi3Mn3O(11+delta): from 45 K antiferromagnetism to room-temperature true ferromagnetism.

The effects of oxygen content on the structural, physical, and chemical properties of Bi(3)Mn(3)O(11) with KSbO(3)-type structure have been investigated. It was found that the oxygen content in Bi(3)Mn(3)O(11+delta) can vary over a wide delta range, keeping the same cubic structure (space group Pn3, a = 9.12172(5) A for delta = -0.5, a = 9.13784(8) A for delta = 0, and a = 9.09863(7) A for delta = 0.6) and semiconducting properties of the material. At the same time, magnetic properties change from true antiferromagnetic with T(N) = 45 K for delta = -0.5 to true ferromagnetic with T(C) = 307 K for delta = +0.6. Bi(3)Mn(3)O(11) (delta = 0) shows ferrimagnetic-like properties with T(C) = 150 K and features typical for a re-entrant spin-glass below 30 K. Noticeable changes of the magnetic transition temperature and magnetism in Bi(3)Mn(3)O(11+delta) with delta can be compared with changes of the magnetic and electronic properties of LaMnO(3+delta), BiMnO(3+delta), high-temperature copper superconductors (e.g., YBa(2)Cu(3)O(7+delta)), and other cuprates. Bi(3)Mn(3)O(11.6) shows a new record high T(C) among insulating/semiconducting true ferromagnets. Our results demonstrate that the oxygen content can vary for the same cation composition in KSbO(3)-type materials, and the oxygen content can be increased up to BiMnO(3.867) (Bi(3)Mn(3)O(11.6)).