Physical properties of Co-substituted iron perovskite systems

ABO(3) type perovskite systems, CaFe1-xCoxO3 (0 less than or equal to x less than or equal to 0.5) and Sr2/3La1/3Fe1-xCoxO3 (0 less than or equal to x less than or equal to 1) were prepared by using a high pressure technique in the presence of an oxidizer KClO4. The parent Fe4+-oxides, CaFeO3 and Sr2/3La1/3FeO3, are both characterized by a charge disproportionation leading to an antiferromagnetic and insulating state, which is 2Fe(4+) --> Fe3+ + Fe5+ for the former and 3Fe(11/3+) --> 2Fe(3+) + Fe5+ for the latter. The Co-substitution leads to a switching to a ferromagnetic and metallic phase. In comparison with the cubic Sr-analogue, the ferromagnetic Curie temperature is lower and the saturation magnetization is smaller, while the coercive force is larger and the resistivity is higher. (C) 1998 Elsevier Science B.V. All rights reserved.