High- and low-temperature crystal and magnetic structures of ε-Fe2O3 and their correlation to its magnetic properties
High- and low-temperature crystal and magnetic structures of ε-Fe2O3 and their correlation to its magnetic properties
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DOI：
10.1021/cm060993l
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发表时间：
2006-08-08
影响因子：
8.6
通讯作者：
Nogues, J.
中科院分区：
文献类型：
--
作者：
Gich, M.;Frontera, C.;Nogues, J.
通过对X射线和中子粉末衍射数据的同时Rietveld精化，结合穆斯堡尔谱，以及磁化强度和热容测量，研究了斜方晶系ε-Fe_2 O_3的晶体和磁性结构。已经发现，在150 K以上，ε-Fe 2 O3多晶型物是共线铁磁体，磁矩沿沿着a轴定向，而在80 K以下的磁有序的特征在于由方波无公度结构。这两种状态之间的转换是一个二级相变，涉及微妙的结构变化，主要影响协调的四面体和八面体Fe网站之一。根据这些结果的ε-Fe 2 O3的磁性能的温度依赖性进行了讨论。
The crystal and magnetic structures of orthorhombic epsilon-Fe2O3 have been studied by simultaneous Rietveld refinement of X-ray and neutron powder-diffraction data in combination with Mossbauer spectroscopy, as well as magnetization and heat-capacity measurements. It has been found that above 150 K, the epsilon-Fe2O3 polymorph is a collinear ferrimagnet with magnetic moments directed along the a axis, whereas the magnetic ordering below 80 K is characterized by a square-wave incommensurate structure. The transformation between these two states is a second-order phase transition and involves subtle structural changes mostly affecting the coordination of the tetrahedral and one of the octahedral Fe sites. The temperature dependence of the epsilon-Fe2O3 magnetic properties is discussed in light of these results.