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

Abstract

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.