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X‐Ray Diffraction and Magnetic Studies of Solid Solutions Bi 1− x Ca x MnO 3
Author(s) -
Bokov V. A.,
Grigoryan N. A.,
Bryzhina M. F.
Publication year - 1967
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.19670200237
Subject(s) - antiferromagnetism , ferromagnetism , monoclinic crystal system , curie temperature , orthorhombic crystal system , perovskite (structure) , crystallography , condensed matter physics , exchange interaction , chemistry , paramagnetism , manganese , materials science , crystal structure , physics , organic chemistry
Solid solutions with the general formula Bi 1– x Ca x MnO 3 (0.2 ≦ x ≦ 1) are found to possess the perovskite structure. The phase diagram based on X‐ray diffraction studies involving cubic, orthorhombic and monoclinic modifications is constructed. It is concluded from conductivity and X‐ray data that the transition into the monoclinic II modification is connected with some type of electron ordering on manganese ions. The changes in the paramagnetic Curie temperature resulting from these structural transitions are discussed. The magnetic ordering occurring in the system at about 110 °K can be explained if Zener's double exchange interaction Mn 3+ ‐O 2− ‐Mn 4+ is assumed to occur only in modifications in which electron ordering does not exist. The antiferromagnetic exchange interaction Mn 4+ ‐O 2− ‐Mn 4+ and the weak exchange interaction Mn 3+ ‐O 2− ‐Mn 3+ (the latter being ferromagnetic at a > 3.8 Å or antiferromagnetic at a < 3.8 Å) are proved to be responsible for ferromagnetism in the range 0.2 ≦ x < 0.4, antiferromagnetism in the range 0.4 ≦ x ≦ 0.8 and weak ferromagnetism in the range 0.8 < x ≦ 1.