Effect of stress induced monoclinic to tetragonal phase transformation in the multiferroic (1-x)BiFeO3-xPbTiO3 system on the width of the morphotropic phase boundary and the tetragonality

The relative stability of the tetragonal and monoclinic phases in the (1-x)BiFeO3-xPbTiO3 solid solution system has been investigated under externally applied stress. It is shown that external stress can transform monoclinic compositions partially to the tetragonal phase in the vicinity of the morphotropic phase boundary (MPB) leading to an extension of the MPB region from Δx ≈ 0.03 for annealed samples to Δx ≈ 0.17 for the stressed samples toward the BiFeO3 richer end. The tetragonality of the stress-induced tetragonal phase for x = 0.20 is shown to be higher than the highest value reported so far for x = 0.31 composition in annealed samples.