The structure of two new non-centrosymmetric phases of oxygen deficient bismuth manganite

The structure of two new phases in the bismuth manganite system are reported. The phases were determined by electron diffraction studies of two oxygen-deficient bulk samples. The first phase, a minority component of bulk BiMnO2.94 forms a n = 2 Ruddlesden-Popper phase with space group Cmc21. The second phase, from bulk BiMnO2.99, is an orthorhombic structure with space groupPmn21 and a unit cell approximately equal to times the parent perovskite cell. Importantly both phases are non-centrosymmetric and offer further potential for multiferroic studies.