Synthesis and Properties of Monoclinic and Cubic Forms of the A-Site-Ordered (BiMn3)Mn4O12 Perovskite

摘要

We have obtained two new A-site-ordered manganese perovskite oxides with the common chemical formula of (BiMn3)Mn4O_(12+δ) with regard to their metal composition. The two phases were prepared through high-pressure synthesis under identical conditions except for the oxygen-to-metal ratio in the precursor mixture. Accordingly, they were found to differ from each other in the oxygen content. The less-oxidized phase possesses a monoclinic crystal structure and shows two magnetic transitions, at 28 and 59 K, whereas the more-strongly-oxidized and hence denser phase with a cubic crystal structure lacks the higher-temperature transition. Thus, the present work has demonstrated an attractive but not-yet-utilized possibility to tailor the properties of (A'A"3)B4O_(12+δ)-type cation-ordered perovskite oxides by means of oxygen-content control.