Hyett Geoffrey, Barrier Nicolas, Clarke Simon J, Hadermann Joke
Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford, OX1 3QR, UK.
J Am Chem Soc. 2007 Sep 12;129(36):11192-201. doi: 10.1021/ja073048m. Epub 2007 Aug 18.
Topotactic modification, by both oxidation and reduction, of the composition, structures, and magnetic properties of the layered oxychalcogenides Sr4Mn3O7.5Cu2Ch2 (Ch=S, Se) is described. These Mn3+ compounds are composed of alternating perovskite-type strontium manganese oxide slabs separated by anti-fluorite-type copper chalcogenide layers and are intrinsically oxide deficient in the central layer of the perovskite slabs. The systems are unusual examples of perovskite-related compounds that may topotactically be both oxidized by fluorination and reduced by deintercalation of oxygen from the oxide-deficient part of the structure. The compounds exhibit antiferromagnetic ordering of the manganese magnetic moments in the outer layers of the perovskite slabs, while the other moments, in the central layers, exhibit spin-glass-like behavior. Fluorination has the effect of increasing the antiferromagnetic ordering temperature and the size of the ordered moment, whereas reduction destroys magnetic long-range order by introducing chemical disorder which leads to both further disorder and frustration of the magnetic interactions in the manganese oxide slab.
描述了通过氧化和还原对层状氧硫属化物Sr4Mn3O7.5Cu2Ch2（Ch = S，Se）的组成、结构和磁性进行的拓扑修饰。这些Mn3+化合物由钙钛矿型锶锰氧化物板和反萤石型铜硫属化物层交替组成，在钙钛矿板的中心层本质上是缺氧化物的。该体系是钙钛矿相关化合物的不寻常例子，它们可以通过氟化进行拓扑氧化，并通过从结构中缺氧化物部分脱嵌氧进行还原。这些化合物在钙钛矿板的外层表现出锰磁矩的反铁磁有序，而在中心层的其他磁矩表现出类似自旋玻璃的行为。氟化具有提高反铁磁有序温度和有序磁矩大小的作用，而还原通过引入化学无序破坏磁长程序，这导致锰氧化物板中磁相互作用的进一步无序和受挫。
