Synthesis and multiferroism in mechanically processed BiFeO3–PbTiO3 ceramics

In this study, (1 − x)BiFeO₃–(x)PbTiO₃ multiferroic ceramics, with x = 0, 0.1, 0.2, 0.25, 0.3 and 0.4, were processed through high-energy ball milling followed by reactive sintering in air atmosphere. The optimization of the procedure for the preparation of highly-dense (1 − x)BiFeO₃–(x)PbTiO₃ ceramics was carefully investigated and structural/microstructural effects on ferroic properties were carefully addressed. Shrinkage dilatometric measurements revealed an expansion related to a sintering reaction that has occurred before densification. This sintering behaviour was highly PbTiO₃ concentration-dependent. The sintering mechanism was found to be directly related with the aliovalent substitution of Pb and Ti ions on A and B sites of the perovskite structure. The obtained ceramics were confirmed as ferroelectric ordered in ferroelectric characterizations. Remnant polarizations and coercive fields greatly dependent on grain size distribution and aliovalent substitutions were revealed. The magnetic hysteresis displayed a weak-ferromagnetic behaviour in all studied samples.