Crystal structure and Ce valence variation in the solid solution CeRh3 − xPdxB0.5
Crystal structure and Ce valence variation in the solid solution CeRh3 − xPdxB0.5
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固溶体 CeRh3 − xPdxB0.5 中的晶体结构和 Ce 价态变化
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
E. Bauer
中科院分区：
文献类型：
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作者：
I. Zeiringer;J. Sereni;M. G. Berisso;K. Yubuta;P. Rogl;A. Grytsiv;E. Bauer
通过X射线粉末衍射、扫描电镜和高分辨电子显微镜，以及低温磁化率和比热测量，研究了固溶体CeRh 3 − xPdxB 0. 5（x = 0，0.5，1.2，1.5，1.7，2.5，3）在铸态下的晶体结构和物理性质。的合金的X射线粉末图案的基础上，在整个解决方案的立方原始AuCu 3晶格的索引显示在三个制度的单调增加。对于0 μ m × 1.5，体积增加仅仅对应于Pd原子取代Rh，其尺寸相当接近。在这种情况下，铈的四价特征不受影响。对于x > 1.5，晶格膨胀变得增强，并且因此归因于Ce原子的逐渐价态变化（中间价态区域）。最后，当x > 2.4时，体系表现出主要的三价行为。在这个区域，比热系数达到4.4 J mol−1 K2，比富Rh边界大两个数量级。CeRh 3 − x Pd x B 0.5化合物的选区电子衍射图案显示出相对于母体AuCu 3结构的1/2 1/2 1/2型超结构和卫星反射。而1/2/2/2型超结构仅限于固溶体的富铑部分，在整个固溶体中观察到卫星反射，并暗示存在由反相边界包围的畴结构。
Crystal structure and physical properties have been studied in the solid solution CeRh3 − xPdxB0.5 (x = 0, 0.5, 1.2, 1.5, 1.7, 2.5, 3) in as-cast state by x-ray powder diffraction and scanning and high-resolution electron microscopy, as well as by low-temperature measurements of the magnetic susceptibility and specific heat. X-ray powder patterns of the alloys were indexed on the basis of a cubic primitive AuCu3 lattice throughout the entire solution showing a monotonous increase in three regimes. For 0 ≦̸ x ≦̸ 1.5, the volume increase corresponds merely to the substitution of Rh by Pd atoms, the sizes of which are rather close. In this regime the tetravalent character of cerium is unaffected. For x > 1.5, the lattice expansion becomes enhanced and is thus attributed to a gradual valence change of the Ce atoms (an intermediate valence regime). Finally, for x > 2.4, the system shows a predominant trivalent behavior. In this region, the specific heat coefficient reaches a value of 4.4 J mol−1 K2, two orders of magnitude larger than that in the Rh-rich border. Selected area electron diffraction patterns of the CeRh3 − x Pd x B0.5 compounds revealed the appearance of ½ ½ ½-type superstructures and satellite reflections with respect to the parent AuCu3 structure. Whereas the ½ ½ ½-type superstructure is confined to the Rh-rich part of the solid solution, satellite reflections are observed throughout the solid solution and hint towards the existence of a domain structure enclosed by anti-phase boundaries.