Mechanosynthesis and structural characterization of the perovskite solid solution (1-x) YMnO3 – xBiFeO3 with 0≤x≤1

Single phase multiferroics have concentrated an increasing attention during the last decade because they are expected to enable a range of potentially disruptive magnetoelectric technologies, such as electrically tunable... [ view full abstract ]

Single phase multiferroics have concentrated an increasing attention during the last decade because they are expected to enable a range of potentially disruptive magnetoelectric technologies, such as electrically tunable microwave magnetic components or spintronic devices, and electrically writable magnetically readable random access memories. Among the different material strategies, phase change phenomena at multiferroic morphotropic phase boundaries in perovskite solid solutions stand out as a promising approach to obtain large room temperature magnetoelectric response [1-3].

We report here our recent results on the mechanosynthesis and structural characterization of the perovskite solid solution YMnO₃-BiFeO₃ as a candidate system to show such morphotropic phase boundary (MPB).  YMnO₃ is a geometric ferroelectric with hexagonal crystal structure that orders antiferromagnetically at ~70 K. A metastable perovskite orthorhombic phase can be obtained by annealing at high pressure or under epitaxial strain, which develops ferroelectric order at a low temperature magnetic transition. BiFeO₃ is the most topical multiferroic material, and one of the rare examples that show both ferroic orders at room temperature. It is a rhombohedral perovskite, and thus a multiferroic orthorhombic-rhombohedral MPB might be formed in the perovskite solid solution. However, its synthesis is challenging. We have succeeded in obtaining nanocrystalline perovskite phases along the whole solid solution by mechanosynthesis in high energy planetary mills. This is an environmentally friendly, versatile technique that has been shown to be very useful as an alternative to high pressure synthesis of metastable perovskite oxides.  Phase thermal stability was defined, and XRD diffraction and Raman spectroscopy studies were accomplished. As a result, the perovskite structural evolution across the system is presented. 

[1] O. Dieguez and J. Iñiguez, Phys. Rev. Lett. 107 art. nº 057601 (2011).

[2] P. Mandal et al., Nature 525 363-367 (2016).

[3] C.M. Fernández-Posada et al, Nature Comm. 7 art. nº 12772  (2016).