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首页> 外文期刊>Nanotechnology >A Y_2O_3:Yb nanoscale magnet obtained by HEBM:C_(3i)/C_2 site occupancies, size/strain analysis and crystal field levels of Yb~(3+) ions
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A Y_2O_3:Yb nanoscale magnet obtained by HEBM:C_(3i)/C_2 site occupancies, size/strain analysis and crystal field levels of Yb~(3+) ions

机译：HEBM：C_（3i）/ C_2的位居占据，尺寸/应变分析和Yb〜（3+）离子的晶体场能获得的Y_2O_3：Yb纳米级磁体

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摘要

A Y_2O_3:Yb nanoscale magnet that belongs to the cubic C-type or bixbyite structure family was synthesized by high energy ball milling (HEBM). An as-prepared sample (S1) was annealed at 650 deg C (S2) and 950 deg C (S3). Cation populations were determined by the refinement of site occupancies. It was found that in S1 and S2 Yb~(3+) ions occupy exclusively the 8b (or C3O position, whereas in S3 a small amount of Yb~(3+) is also located on Wyckoff-site 24d (or C_2). X-ray powder diffraction line broadening analysis was done by using the Rietveld method using regular TCH-pV functions (isotropic effects) and symmetrized cubic harmonics (anisotropic effects) for the refinement. The line broadening anisotropy decreases due to strain effects from S1 to S3, while the crystallite size anisotropy increases from S1 to S3. Transmission electron microscopy (TEM) and Raman spectroscopy were used to define the homogeneity, microstructure and to locally probe the structure of the samples S1-S3. Magnetic susceptibility results in the 2-300 K temperature regions were analysed by applying the first-order perturbation theory. The mean energy gap between ground and excited crystal field levels (Ei), and their effective magnetic numbers M_(ieff), were determined. The analysis of the paramagnetic temperature shows the absence of clusterization of the magnetic ions.
机译：通过高能球磨（HEBM）合成了属于立方C型或方铁矿结构族的Y_2O_3：Yb纳米级磁体。将准备好的样品（S1）在650摄氏度（S2）和950摄氏度（S3）退火。阳离子的数量由场地占用率的提高确定。发现在S1和S2中，Yb〜（3+）离子仅占据8b（或C3O位置），而在S3中，少量Yb〜（3+）也位于Wyckoff位点24d（或C_2）上。利用常规的TCH-pV函数（各向同性效应）和对称三次谐波（各向异性效应）的Rietveld方法进行X射线粉末衍射谱线展宽分析，由于从S1到S3的应变效应，谱线展宽各向异性减小。 ，而从S1到S3的晶粒尺寸各向异性增加，使用透射电子显微镜（TEM）和拉曼光谱法确定样品S1-S3的均匀性，微观结构并局部探测其结构，磁化率为2-300应用一阶扰动理论分析了K个温度区域，确定了地基和激发态晶体能级（Ei）之间的平均能隙，以及它们的有效磁数M_（ieff）。温度表明没有磁性离子的聚集。

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