Structural and Magnetic Phase Transitions in the Fe-Rich Compositional Range of the Multiferroic BiFe1-x[Zn0.5Ti0.5]xO3 Perovskites

The (1-x)BiFeO3-xBiZn0.5Ti0.5O3 solid solutions (0.05 ≤ x ≤ 0.25) were prepared using high-pressure synthesis. Up to 25 at.% substitutions of Fe by the combination of [Mg0.5Ti0.5] were found to increase the unit cell volume of the primitive perovskite cell, while the crystal structure remains the rhombohedral perovskite, as that in the parent BiFeO3. With increasing temperature, the as-prepared ceramics of the x = 0.25 composition reversibly transform into a cubic modification between about 970 and 1070 K. However, this phase transition is overlapped with a gradual decomposition of the perovskite phase, which starts above 770 K. The perovskite phase with the substitution rate corresponding to x = 0.25 is antiferromagnetic below TN∼460 K. Peculiarities of the temperature-dependent magnetic behavior of this composition at about 220 and 315 K, which might indicate transitions between the states with different magnetic orderings, have been observed.