open access

https://hdl.handle.net/2115/44030

Magnetic and electrical properties of quadruple perovskites with 12 layer structures Ba4LnM3O12 (Ln=rare earths; M=Ru, Ir) : The role of metal-metal bonding in perovskite-related oxides

英語

Specific heat

2010-09

Elsevier

Journal of Solid State Chemistry

183(9)

1962-1969

Structures and magnetic and electrical properties of quadruple perovskites containing rare earths Ba4LnM3O12 (Ln = rare earths; M=Ru, Ir) were investigated. They crystallize in the 12L-perovskite-type structure. Three MO6 octahedra are connected to each other by face-sharing and form a M3O12 trimer. The M3O12 trimers and LnO6 octahedra are alternately linked by corner-sharing, forming the perovskite-type structure with 12 layers. For Ln = Ce, Pr, and Tb, both the Ln and M ions are in the tetravalent state (Ba4Ln^[4+]M^[4+]_[3]O12), and for other Ln ions, Ln ions are in the trivalent state and the mean oxidation state of M ions is +4.33 (Ba4Ln^[3+]M^[4.33+]_[3]O12). All the Ba4Ln^[3+]Ru^[4.33+]_[3]O12 compounds show magnetic ordering at low temperatures, while any of the corresponding iridium-containing compounds Ba4Ln^[3+]Ir^[4.33+]_[3]O12 is paramagnetic down to 1.8K. Ba4Ce^[4+]Ir^[4+]_[3]O12 orders antiferromagnetically at 10.5 K, while the corresponding ruthenium-containing compound Ba4Ce^[4+]Ru^[4+]_[3]O12 is paramagnetic. These magnetic results were well understood by the magnetic behavior of M3O12. The effective magnetic moments and the entropy change for the magnetic ordering show that the trimers Ru^[4.33+]_[3]O12 and Ir^[4+]_[3]O12 have the S=1/2 ground state, and in other cases there is no magnetic contribution from the trimers Ru^[4+]_[3]O12 or Ir^[4.33+]_[3]O12. Measurements of the electrical resistivity of Ba4LnM3O12 and its analysis show that these compounds demonstrate two-dimensional Mott-variable range hopping behavior.

学術雑誌論文

Accepted Manuscript

0022-4596