Comparative study of the magnetic properties of La3Ni2B'O9 for B' = Nb, Taor Sb
Comparative study of the magnetic properties of La3Ni2B'O9 for B' = Nb, Taor Sb
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B=Nb、Taor Sb的La3Ni2BO9磁性能对比研究
DOI：
10.1016/j.jssc.2017.12.018
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发表时间：
2018
影响因子：
3.3
通讯作者：
Chin C
中科院分区：
文献类型：
--
作者：
Chin C
对La_3Ni_2NbO_9和La_3Ni_2TaO_9多晶样品进行了X射线和中子衍射、电子显微镜、磁测量和介子自旋弛豫(µSR)的表征，后者也适用于La_3Ni_2SbO_9。在中子衍射实验的长度尺度上，单斜钙钛矿结构的六个坐标位置被Ni和随机的⅓Ni/⅔B‘混合物以1：1的顺序占据。电子显微镜显示，这种1：1的有序性在微观距离上保持不变，尽管观察到混合部位上的漫反射表明存在短程有序化。在5℃下，从La3Ni2B‘O9(B’=Nb或Ta)收集的中子衍射图中没有观察到磁布拉格散射，尽管在每一种情况下，µSR都发现了30℃以下静态自旋的存在。磁学测量表明，在29℃以下，La3Ni2NbO9表现为自旋玻璃，但在85℃以下，La3Ni2TaO9存在显著的短程相互作用。
Polycrystalline samples of La3Ni2NbO9and La3Ni2TaO9have been characterised by X-ray and neutron diffraction, electron microscopy, magnetometry and muon spin relaxation (µSR); the latter technique was also applied to La3Ni2SbO9. On the length scale of a neutron diffraction experiment, the six-coordinate sites of the monoclinic perovskite structure are occupied in a 1:1 ordered manner by Ni and a random ⅓Ni/⅔B′mixture. Electron microscopy demonstrated that this 1:1 ordering is maintained over microscopic distances, although diffuse scattering indicative of short-range ordering on the mixed site was observed. No magnetic Bragg scattering was observed in neutron diffraction patterns collected from La3Ni2B′O9(B′= Nb or Ta) at 5 K although in each case µSR identified the presence of static spins below 30 K. Magnetometry showed that La3Ni2NbO9behaves as a spin glass below 29 K but significant short-range interactions are present in La3Ni2TaO9below 85 K. The contrasting properties of these compounds are discussed in terms of their microstructure.