An Ordered Assembly of Filled Nanoscale Tubules of Europium Seleno-silicate in the Crystal Structure of a Quaternary Compound

摘要

Recently, there have been several reports of an attractive class of compounds containing nanoscale features in extended solids. These nanoscale features include tubules and spheres in well-defined compounds, especially in oxides and chalcogenides. For example, nanotubules are observed in the structures of Na_2V_3O_7, (C_4H_(12)N)_(14)-[(UO_2)_(10)(SeO_4)_(17)(H_2O)], K_5[(UO_2)_3(SeO_4)_5](NO_3)(H_2O)_(3.5) and SbPS_4 and nanospheres in some actinyl peroxides. These compounds with nanotube features are different from those compounds having one-dimensional (1-D) channels or tunnels fused through covalent bonds to form three-dimensional (3-D) structures as in open framework compounds. Moreover, they are also different from the so-called "inorganic nanotubes", which are formed by rolling up exfoliated single or multilayered sheets of a layered compound. The nanotubes in well-defined compounds are often negatively charged and held together in the crystal through ionic or other weaker forces in the 3-D crystalline assembly. In this Communication, we report the first example of a rare-earth based chalcogenide material featuring a tubular structure.