National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA.
Ultramicroscopy. 2013 Apr;127:94-9. doi: 10.1016/j.ultramic.2012.07.019. Epub 2012 Jul 27.
A newly discovered 1:3 A-site-ordered AA'3B4O12 perovskite oxide CaCu3Ir4O12 which has unusual electrical and magnetic properties was investigated using STEM imaging and EELS techniques in a probe corrected microscope. The target sample was compared with the other two iso-structural oxides of CaCu3Ru4O12 and CaCu3Ti4O12 with dissimilar physical properties. It has been found by STEM HAADF imaging that Ca and Cu on A and A' sites are ordered as expected. Oxygen atoms are imaged with STEM ABF imaging. The fine structures of the Cu L2,3 core loss and O-K edges show that the electronic structure of CaCu3Ir4O12 is very close to that of CaCu3Ru4O12, but different from CaCu3Ti4O12. The O-K near edge fine structures show extensive hybridization of Ir 5d and O 2p band. Cu L2,3 peaks indicate Cu in CaCu3Ir4O12 has 2+ valence, though Cu(2+) electrons mainly localized, they might have strong interactions with Ir(4+) 5d electrons through Ir-O-Cu, similar to the strong coupling of Ru with Cu in CaCu3Ru4O12.
一种新发现的 1:3 A 位有序 AA'3B4O12 钙铜铱钙钛矿氧化物 CaCu3Ir4O12 具有不寻常的电学和磁学性质，使用探针校正显微镜中的 STEM 成像和 EELS 技术进行了研究。目标样品与其他两种具有不同物理性质的同构钙铜铱钙钛矿氧化物 CaCu3Ru4O12 和 CaCu3Ti4O12 进行了比较。STEM HAADF 成像表明，A 和 A'位的 Ca 和 Cu 如预期的那样有序。用 STEM ABF 成像对氧原子进行成像。Cu L2,3 芯损耗和 O-K 边的精细结构表明，CaCu3Ir4O12 的电子结构非常接近 CaCu3Ru4O12，但与 CaCu3Ti4O12 不同。O-K 近边精细结构显示 Ir 5d 和 O 2p 带的广泛杂化。Cu L2,3 峰表明 CaCu3Ir4O12 中的 Cu 具有 2+价态，尽管 Cu(2+)电子主要局域化，但它们可能通过 Ir-O-Cu 与 Ir(4+) 5d 电子具有强烈相互作用，类似于 CaCu3Ru4O12 中 Ru 与 Cu 的强耦合。
