Baranets Sviatoslav, Ovchinnikov Alexander, Bobev Svilen
Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States of America.
Department of Materials and Environmental Chemistry, Stockholm University, Stockholm 10691, Sweden.
Inorg Chem. 2021 May 3;60(9):6702-6711. doi: 10.1021/acs.inorgchem.1c00519. Epub 2021 Apr 9.
A systematic investigation of the ternary system Yb-Mn-Sb led to the discovery of the novel phase YbMnSb. Its crystal structure was characterized by single-crystal X-ray diffraction and found to be complex and highly disordered. The average YbMnSb structure can be considered to represent a defect modification of the CaLiMgSb type and to crystallize in the tetragonal 4/ space group (No. 136) with four formula units per cell. The structural disorder can be associated with both occupational and positional effects on several Yb and Mn sites. Similar traits were observed for the structure of the recently reported YbMnSb phase (monoclinic space group 2/, No. 15), which was reevaluated as part of this study as well. In both structures, distorted Sb octahedra centered by Yb atoms and Sb tetrahedra centered by Mn atoms form disordered fragments, which appear as the hallmark of the structural chemistry in this system. Discussion along the lines of how difficult, and important, it is to distinguish YbMnSb from the compositionally similar binary YbSb and ternary YbMnSb compounds is also presented. Preliminary transport measurements for polycrystalline YbMnSb indicate high values of the Seebeck coefficient, approaching 210 μV K at 600 K, and a semiconducting behavior with a room-temperature resistivity of 114 mΩ cm.
对三元体系Yb-Mn-Sb进行的系统研究导致发现了新相YbMnSb。通过单晶X射线衍射对其晶体结构进行了表征，发现其结构复杂且高度无序。平均YbMnSb结构可被认为是CaLiMgSb型的缺陷变体，以四方晶系4/空间群（编号136）结晶，每个晶胞含四个化学式单元。结构无序与几个Yb和Mn位点上的占位和位置效应有关。最近报道的YbMnSb相（单斜空间群2/，编号15）的结构也观察到了类似特征，作为本研究的一部分，对其进行了重新评估。在这两种结构中，以Yb原子为中心的扭曲Sb八面体和以Mn原子为中心的Sb四面体形成无序片段，这似乎是该体系结构化学的标志。还讨论了区分YbMnSb与组成相似的二元YbSb和三元YbMnSb化合物有多困难以及有多重要。多晶YbMnSb的初步输运测量表明，塞贝克系数较高，在600 K时接近210 μV K，且具有半导体行为，室温电阻率为114 mΩ cm。
