Synthesis, Structure and Electromagnetic Properties of Manganese Hollandite, KxMn8O16
Synthesis, Structure and Electromagnetic Properties of Manganese Hollandite, KxMn8O16
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锰锰矿KxMn8O16的合成、结构及电磁性能
DOI：
10.1143/jpsj.81.104701
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
and Y. Ueda
中科院分区：
文献类型：
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作者：
T. Kuwabara;M. Isobe;H. Gotou;T. Yagi;D. Nishio-Hamane;and Y. Ueda
采用高压合成法制备了钾锰锰氧化物K1. 6 Mn 8 O 16，并对其结构和电磁性能进行了研究。K_（1.6）Mn_8 O_（16）具有1/5摩尔的K空位和Mn_（3.8+）的形式价态（Mn_（3+）/Mn_（4+）= 1/4）。它在250和380 K下表现出连续的结构转变。在250 K的转变中出现了沿单斜b轴（隧道方向）沿着具有五倍周期性的超结构，表明Mn ~（4+）和Mn ~（3+）之间存在K空位有序和电荷有序。K1.6Mn8O16中每5个Mn ~（4+）离子有1个额外的电子，这些额外的电子被邻近K空位的Mn ~（3+）离子俘获，形成Mn ~（3+）态。K1.6Mn8O16在很宽的温度范围内表现出一维（1D）系统的变程跳跃型导电性，是一种倾斜的反铁磁体，|θCW/TN|这表明一种挫折效应，正如从结构中的曲折链所预期的那样。
Potassium manganese hollandite, K1.6Mn8O16, was prepared by high-pressure synthesis and its structure and electromagnetic properties were investigated. K1.6Mn8O16has K-vacancies of 1/5 mol and the formal valence of Mn3.8+(Mn3+/Mn4+= 1/4). It shows successive structural transitions at 250 and 380 K. The superstructure with fivefold periodicity along the monoclinicb-axis (tunnel direction) appears in the transition at 250 K, indicating the occurrence of K-vacancy order and charge order between Mn4+and Mn3+. K1.6Mn8O16has one extraeg-electron per five Mn4+ions, and these extra electrons are trapped by Mn ions adjacent to K-vacancies, resulting in the Mn3+state. K1.6Mn8O16shows a variable-range-hopping-type conductivity of a one-dimensional (1D) system in a wide temperature region and is a canted antiferromagnet with a considerable ratio of |θCW/TN|≈6, which indicates a frustration effect, as expected from the zigzag chains in the structure.