Mechanosynthesis and multiferroic properties of the BiFeO3–BiMnO3–PbTiO3 ternary system along its morphotropic phase boundary

A highly topical set of materials are those ABO3 perovskite oxides, in which multiferroicity is chemically engineered by placing ferroelectrically and magnetically active cations in A- and B-site, respectively. This is the case of the BiFeO3 and BiMnO3 perovskites, and also of the solid solutions they form with PbTiO3. Interest in these binary systems is fostered by the presence of distinctive morphotropic phase boundaries (MPBs), multiferroic in the case of BiFeO3–PbTiO3, for which a high magnetoelectric response has been anticipated. Here, new compositions belonging to the ternary system BiFeO3–BiMnO3–PbTiO3, and specifically along the line that joins the former MPBs, have been prepared by mechanosynthesis to accomplish a thorough analysis of their multiferroic nature. Nanocrystalline powders with a perovskite-type structure were obtained in the entire range of compositions, which all exhibited polymorphic phase coexistence allowing a line of MPBs to be established. The variation of the perovskite structural characteristics along this line has been defined, and correlated with those of the magnetic and electrical properties. A set of novel and promising multiferroic materials have been found for BiFeO3 rich compositions.