Lind Hanna, Boström Magnus, Petrícek Vaclav, Lidin Sven
Department of Inorganic Chemistry, Stockholm University, 10691 Stockholm, Sweden.
Acta Crystallogr B. 2003 Dec;59(Pt 6):720-9. doi: 10.1107/s0108768103019694. Epub 2003 Nov 25.
The novel structure of the delta1 phase in the cobalt-zinc system was determined by single-crystal X-ray diffraction. The structure features fused double icosahedra linked by edge- and face-sharing. The delta1-CoZn(7.8) structure is incommensurately modulated along the columnar b direction. The extent of the linear pentagonal antiprismatic intergrowth is limited to a maximum of two overlapping icosahedra because of geometric demands and radii relations. Even this limited fusion of icosahedra leads to strain that is believed to be the origin of the structural modulation. The compound was synthesized using a centrifugation-aided filtration method which yielded single crystals grown on cobalt pieces in a zinc-rich melt. The (3 + 1)-dimensional superspace group is F2/m(0beta0)s0 and the modulation wavevector was determined to q = 0.234b*. The partial amorphization of the sample when subjected to mechanical grinding is an indication of a metastable structure. The incommensurability of the structure may be seen as an ordered pinning of phasons.
通过单晶X射线衍射确定了钴锌体系中δ1相的新颖结构。该结构的特征是通过边共享和面共享连接的融合双二十面体。δ1-CoZn(7.8)结构沿柱状b方向存在非公度调制。由于几何要求和半径关系，线性五角反棱柱共生的程度限制在最多两个重叠的二十面体。即使是这种有限的二十面体融合也会导致应变，据信这是结构调制的起源。该化合物采用离心辅助过滤法合成，该方法产生了在富锌熔体中的钴片上生长的单晶。(3 + 1)维超空间群为F2/m(0β0)s0，调制波矢确定为q = 0.234b*。样品在机械研磨时的部分非晶化表明其结构是亚稳的。该结构的非公度性可以被视为相子的有序钉扎。
