Ferroelectric order stability in the Bi1-xPbxFeO3 solid solution

Ferroelectric properties of Bi1-xPbxFeO3, through a structural approach, by structural Rietveld refinement and x-ray diffraction versus temperature have been carried out. This study allows us to draw a phase diagram for the system Bi1-xPbxFeO3. Although lead atom gets a lone pair and is commonly understood as having a ferroelectric character, we report in this paper that adding of lead atom in the Bi subsystem of BiFeO3, destroys the long-range FE order induced by Bi lone pairs on contrary, and progressively breaks the ferroelectric ordering up to the point where the structure becomes cubic on average. The decreasing of T-C with increasing Pb content also confirms that adding of Pb atoms destabilizes the ferroelectric rhombohedral order and stabilizes the cubic phase via a complex texture of mixed phases, occurring at a local scale.