摘要：Since the discovery of the first drum-like CoB16- complex, metal-doped drum-like boron nanotubular structures have been investigated with various metal dopants and different tubular size, forming a new class of novel nanostructures. The CoB16- cluster was found to be composed of a central Co atom coordinated by two fused B8 rings in a tubular structure, representing the potential embryo of metal-filled boron nanotubes and providing opportunities to design one-dimensional metal-boron nanostructures. Here we report improved photoelectron spectroscopy and a more in-depth electronic structure analysis of CoB16-, providing further insight into the chemical bonding and stability of the drum-like doped boron tubular structures. Most interestingly, we find that the central Co atom has an unusually low oxidation state of ?1 and neutral CoB16 can be viewed as a charge transfer complex (Co-@BB16+), suggesting both covalent and electrostatic interactions between the dopant and the boron drum.

摘要：To accelerate the development and design of magnesium(Mg)alloys,the structural and mechanical properties of important precipitates in Mg−Zn alloys were studied by experiments and density functional *** nano-indentation tests revealed that the hardness of the precipitates initially increased and then decreased with increasing Zn content,and was significantly higher than that of pure Mg and *** calculation results revealed that the precipitates stability initially increased and then decreased with increasing Zn *** bulk moduli of the precipitates increased,whereas their shear and Young’s moduli initially increased and then decreased with increasing Zn *** decreasing order of ductility for these compounds is MgZn_(2)>Mg_(21)Zn_(25)>Mg_(2)Zn_(11)>Mg_(4)Zn_(7).The surface profiles of the compounds revealed that they are obvious *** the degree of covalency and bond length of covalent bonds initially increased and then decreased with increasing Zn content.