Magnetic Behaviour of Perovskite Compositions Derived from BiFeO3.

The phase content and sequence, the crystal structure, and the magnetic properties of perovskite solid solutions of the (1-y)BiFeO₃-yBiZn_0.5Ti_0.5O₃ series (0.05 ≤ y ≤ 0.90) synthesized under high pressure have been studied. Two perovskite phases, namely the rhombohedral R3c and the tetragonal P4mm, which correspond to the structural types of the end members, BiFeO₃ and BiZn_0.5Ti_0.5O₃, respectively, were revealed in the as-synthesized samples. The rhombohedral and the tetragonal phases were found to coexist in the compositional range of 0.30 ≤ y ≤ 0.90. Magnetic properties of the BiFe_1-y[Zn_0.5Ti_0.5]yO₃ ceramics with y < 0.30 were measured as a function of temperature. The obtained compositional variations of the normalized unit-cell volume and the Néel temperature of the BiFe_1-y[Zn_0.5Ti_0.5]yO₃ perovskites in the range of their rhombohedral phase were compared with the respective dependences for the BiFe_1-yB³⁺ yO₃ perovskites (where B³⁺ = Ga, Co, Mn, Cr, and Sc). The role of the high-pressure synthesis in the formation of the antiferromagnetic states different from the modulated cycloidal one characteristic of the parent BiFeO₃ is discussed. [ABSTRACT FROM AUTHOR]