Ferroic states in La doped BiFeO3-PbTiO3 multiferroic compounds

In this paper, the relationship between ferroic states and the physicochemical mechanism which governs the (Bi/Pb/La)-O bonds in polycrystalline La doped (0.6) BiFeO3-(0.4) PbTiO3 compounds were investigated. An abrupt change in the symmetries of perovskite-structured samples, from tetragonal (P4mm) to rhombohedral (R3c), occurs with the increase of the La concentration, highlighting the diminishment of the hybridization of the (Bi/Pb)-O bonds when La is added into the solid solution, and the emergence of a characteristic morphotropic phase boundary tuned by doping. A maximum remnant polarization (10 mu C/cm(2)) was observed for low La concentrations (where R3c and P4mm phases coexist), while the maximum remnant magnetization (similar to 75 x 10(-3) emu/g) was observed for highly La concentrated samples. These results show that ferroelectric and weak-ferromagnetic orders are strongly correlated to the structural arrangement, which in turn are directly related to the chemical A-O and B-O bonds (long-range and short-range forces) and with the chemical characteristics of the elements that fulfills the A site of the perovskite structure. (C) 2012 American Institute of Physics. [http://dx. doi. org/10.1063/1.4729288]