Chan T S, Liu R S, Yang C C, Li W-H, Lien Y H, Huang C Y, Lynn Jeff W, Chen J M, Sheu H-S
Department of Chemistry and Center for Nano Storage Research, National Taiwan University, Taipei 106, Taiwan.
Inorg Chem. 2007 May 28;46(11):4575-82. doi: 10.1021/ic070190f. Epub 2007 May 2.
The crystallographic and magnetic behaviors of (Tb1-xNax)MnO3-y (0<or=x<or=0.3) have been studied by neutron powder diffraction (NPD), synchrotron X-ray powder diffraction, and Raman spectroscopy techniques. Although Na+ ions have larger ionic radii than Tb3+ ions, analysis of NPD data reveals a decrease in cell volume upon Na-doping, which can be explained solely by the occurrence of oxygen deficiencies and not by the size effect. The Raman spectrum represents the variation in bond length and bond angle, which originates from the balance of ions, asymmetric structure, and defects in the system. Na-doping causes an oxygen deficiency, and consequently, a peak shift is seen in the Raman spectrum because of the structural adjustment resulting from the doping. The observed effective moments decrease with increasing x because of the replacement of Tb3+ ions by Na+ ions. The well-defined peak at approximately 45 K (labeled TMn) of the x=0.3 sample is associated with Mn spin ordering, while the magnetic responses associated with TMn are not clearly present in the x=0.15 and x=0 samples.
通过中子粉末衍射（NPD）、同步辐射X射线粉末衍射和拉曼光谱技术研究了（Tb1-xNax）MnO3-y（0≤x≤0.3）的晶体学和磁行为。尽管Na+离子的离子半径大于Tb3+离子，但对NPD数据的分析表明，Na掺杂后晶胞体积减小，这只能用氧缺陷的出现来解释，而不能用尺寸效应来解释。拉曼光谱表示键长和键角的变化，其源于系统中离子的平衡、不对称结构和缺陷。Na掺杂会导致氧缺陷，因此，由于掺杂引起的结构调整，拉曼光谱中会出现峰位移。由于Na+离子取代了Tb3+离子，观察到的有效磁矩随着x的增加而减小。x = 0.3样品在约45 K处（标记为TMn）明确的峰与Mn自旋有序相关，而与TMn相关的磁响应在x = 0.15和x = 0的样品中不明显。
