Neutron‐Diffraction Study of Antiferromagnetic Ba2CoWO6 and Ba2NiWO6
Neutron‐Diffraction Study of Antiferromagnetic Ba2CoWO6 and Ba2NiWO6
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反铁磁 Ba2CoWO6 和 Ba2NiWO6 的中子衍射研究
DOI：
10.1063/1.1709666
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发表时间：
1967
影响因子：
3.2
通讯作者：
B. Frazer
中科院分区：
文献类型：
--
作者：
D. Cox;G. Shirane;B. Frazer
许多有序的钙钛矿型化合物A2BB′O6，其中B和B′分别是3d过渡金属阳离子和抗磁性阳离子，经历反铁磁转变。后者已被解释在第二类反铁磁有序所产生的可观的超交换相互作用在相当长的距离，涉及两个阴离子和一个抗磁性阳离子。一个中子衍射研究已经取得了两个这样的化合物，Ba2CoWO6和Ba2NiWO6的多晶样品。晶体结构是立方的，并且存在氧离子从理想的钙钛矿位置朝向约0.1 A的更高电荷的W离子的轻微位移。在4.2°K时，两种化合物的磁性晶胞边缘都是晶胞边缘的两倍，观察到的磁性峰与第二类有序一致。Ba2NiWO6中的自旋方向垂直于[111]轴，但在Ba2CoWO6中，它似乎与[111]轴成大约20°。
A number of ordered perovskite‐type compounds A2BB′O6, in which B and B′ are, respectively, a 3d transition metal cation and a diamagnetic cation, undergo antiferromagnetic transitions. The latter have been interpreted in terms of antiferromagnetic ordering of the second kind arising from appreciable superexchange interactions over quite long distances involving two anions and one diamagnetic cation. A neutron diffraction study has been made of polycrystalline samples of two such compounds, Ba2CoWO6 and Ba2NiWO6. The crystal structures are cubic, and there is a slight displacement of the oxygen ions from the ideal perovskite positions towards the more highly charged W ions of about 0.1 A. At 4.2°K the magnetic unit cell edge is double that of the crystallographic cell in both compounds and the observed magnetic peaks are consistent with ordering of the second kind. The spin direction in Ba2NiWO6 is perpendicular to the [111] axis, but in Ba2CoWO6 it appears to lie roughly 20° from the [111] axis.