Structural defects in multiferroic BiMnO₃ studied by transmission electron microscopy and electron energy-loss spectroscopy

The multiferroic material BiMnO₃ synthesized under high pressure has been systematically studied by transmission electron microscopy and electron energy-loss spectroscopy, and some important structural defects are revealed in this multiferroic material. The frequently observed defects are characterized to be ∑3(11̄1) twin boundaries, Ruddlesden-Popper [Acta Crystallogr. 11, 54 (1958)] antiphase boundaries, and a _p〈001〉_p superdislocations connected with a small segment of Ruddlesden-Popper defect. These defects are present initially in the as-synthesized sample. In addition, we find that ordered voids (oxygen vacancies) are easily introduced into the multiferroic BiMnO₃ by electron-beam irradiation.