Effect of crystallite size and clustering in influencing the stability of phases of a very large tetragonality ferroelectric system 0.6BiFeO3–0.4PbTiO3

The role of crystallite size and clustering in influencing the stability of the structures of a large tetragonality ferroelectric system 0.6BiFeO3–0.4PbTiO3 was investigated. The system exhibits cubic phase for a crystallite size ∼25 nm, three times larger than the critical size reported for one of its end member PbTiO3. With increased degree of clustering for the same average crystallite size, partial stabilization of the ferroelectric tetragonal phase takes place. The results suggest that clustering helps in reducing the depolarization energy without the need for increasing the crystallite size of free particles.

► Size effect in a large tetragonality, high Curie point ferroelectric system.
► Smallest critical size three times bigger than for the case of PbTiO3.
► Explanation provided for the enhancement of the minimum critical size.
► Phase change shown due to sufficient clustering of subcritical sized grains.
► Emphasis on clustering and crystallite size in influencing the depolarization energy.