New quaternary complex borides, Ti9M2Ru18B8 (Cr, Mn, Co, Ni, Cu, Zn): synthesis, crystal structure and bonding analysis
New quaternary complex borides, Ti9M2Ru18B8 (Cr, Mn, Co, Ni, Cu, Zn): synthesis, crystal structure and bonding analysis
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新型四元复合硼化物 Ti9M2Ru18B8（Cr、Mn、Co、Ni、Cu、Zn）：合成、晶体结构和成键分析
DOI：
10.1524/zkri.2010.1239
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
M. Gilleßen
中科院分区：
文献类型：
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作者：
B. Fokwa;C. Goerens;M. Gilleßen
摘要 用这些元素合成了 Ti9M2Ru18B8（Cr、Mn、Co、Ni、Cu、Zn）相的粉末样品和单晶，并通过粉末和单晶 X 射线衍射以及能量色散 X 射线分析进行了表征。新相都是同型的，并在四方晶系中结晶，作为 Zn11Rh18B8 型结构的替代变体（空间群 P4/mbm，编号 127）。观察M2哑铃并沿[001]方向相互连接以构建“梯子”。 M–M 哑铃距离从 2.48 到 2.50 Å 不等，两个哑铃之间的距离 (M2 · · · M2) 都接近 2.97 Å，而链之间的距离至少为 11.20 Å。在该系列中观察到晶胞体积随着价电子数的增加而发生强烈变化。根据紧束缚电子结构计算的结果，Ru-B 和 Ti-Ru 接触负责这些相的结构稳定性。 M-M 和 M-Ru 相互作用的强度随着系列中价电子数的增加而降低。费米能级的非消失态密度表明所有相的金属特性。
Abstract Powder samples and single crystals of the Ti9M2Ru18B8 (Cr, Mn, Co, Ni, Cu, Zn) phases were synthesized from the elements and characterized by powder and single-crystal X-ray diffraction as well as energy-dispersive X-ray analysis. The new phases are all isotypic and crystallize in the tetragonal system as substitutional variants of the Zn11Rh18B8-type structure (space group P4/mbm, no. 127). M2 dumbbells are observed and interconnect to each other along the [001] direction to build “ladders”. The M–M dumbbell distances vary from 2.48 to 2.50 Å and the distances between two dumbbells (M2 · · · M2) are all close to 2.97 Å, whereas the chains are well separated from each other by distances of at least 11.20 Å. A strong variation of the unit cell volume with increasing valence electron count is observed in the series. According to the results of tight-binding electronic structure calculations, Ru–B and Ti–Ru contacts are responsible for the structural stability of these phases. The strength of the M–M and M–Ru interactions decreases with increasing valence electron count in the series. Non vanishing density of states at the Fermi level indicates metallic character for all phases.