Spin Glass to Weak Ferromagnetic Transformation in a New Layered Cobaltite: Consequence of Topotactic Reactions with Water at Room Temperature.
Spin Glass to Weak Ferromagnetic Transformation in a New Layered Cobaltite: Consequence of Topotactic Reactions with Water at Room Temperature.
复制标题
自旋玻璃到新型层状钴矿中的弱铁磁转变：室温下与水的拓扑反应的结果。
DOI：
10.1002/chin.200609016
复制
发表时间：
2006
期刊：
影响因子：
--
通讯作者：
A. Maignan
中科院分区：
文献类型：
--
作者：
T. Motohashi;B. Raveau;V. Caignaert;V. Pralong;M. Hervieu;D. Pelloquin;A. Maignan
Ruddlesden−Popper（RP）钴矿系列的新= 2成员Sr 3-δCo1.9Nb0.1O6.65-δ已通过铌掺杂得到稳定。该氧化物与大气中的水通过水解/水合和钴的还原而发生拓扑反应，产生羟基氧化物水合物衍生物Sr 3-δ Co 1.9Nb 0.1O 4.86-δ（OH）3.04·0.4H2O。在室温下与水的反应诱导磁性转变从自旋玻璃行为与冻结温度Tg <$50 K的原始RP氧化物的弱铁磁性与表观居里温度TC <$200 K的羟基氧化物水合物衍生物。水对这种层状氧化物的磁性能的壮观的效果被解释为部分还原的Co 4+到Co 3+物种，伴随着诱导的钴阳离子，形成高自旋Co 3+之间的反铁磁耦合的配位变化。这一现象被认为是其他层状钴矿，甚至铁氧化物的推广。
A newn= 2-member of the Ruddlesden−Popper (RP) cobaltite series, Sr3-δCo1.9Nb0.1O6.65-δ, has been stabilized by niobium doping. This oxide reacts topotactically with atmospheric water through hydrolysis/hydration and reduction of cobalt, leading to an oxyhydroxide hydrate derivative, Sr3-δCo1.9Nb0.1O4.86-δ(OH)3.04·0.4H2O. The reaction with water at room temperature induces a magnetic transformation from a spin glass behavior with a freezing temperatureTg≈ 50 K for the pristine RP oxide to weak ferromagnetism with an apparent Curie temperatureTC≈ 200 K for the oxyhydroxide hydrate derivative. The spectacular effect of water upon the magnetic properties of this layered oxide is explained by the partial reduction of Co4+into Co3+species, concomitantly inducing a coordination change for cobalt cations that form antiferromagnetic coupling between high-spin Co3+. A generalization of this phenomenon to other layered cobaltites and even iron oxides is considered.