No abstract

No abstract

No abstract

The structural organization of compounds in a confined space of nanometer-scale cavities is of fundamental importance for understanding the basic principles for atomic structure design at the nanolevel. Here, we explore size-dependent structure relations between one-dimensional PbTe nanocrystals and carbon nanotube containers in the diameter range of 2.0-1.25 nm using high-resolution transmission electron microscopy and ab initio calculations. Upon decrease of the confining volume, one-dimensional crystals reveal gradual thinning, with the structure being cut from the bulk in either a <110> or a <100> growth direction until a certain limit of ∼1.3 nm. This corresponds to the situation when a stoichiometric (uncharged) crystal does not fit into the cavity dimensions. As a result of the in-tube charge compensation, one-dimensional superstructures with nanometer-scale atomic density modulations are formed by a periodic addition of peripheral extra atoms to the main motif. Structural changes in the crystallographic configuration of the composites entail the redistribution of charge density on single-walled carbon nanotube walls and the possible appearance of the electron density wave. The variation of the potential attains 0.4 eV, corresponding to charge density fluctuations of 0.14 e/atom.

Single-wall carbon nanotubes (SWCNTs) are of the greatest interest for application in materials used for various purposes due to all of their unique properties. However, the practical use of SWCNTs has, until quite recently, been limited by the absence of a cheap industrial process for manufacturing them. Currently, a technology for the synthesis of SWCNTs from hydrocarbon raw materials providing the initial SWCNTs product of a sufficiently high quality has been developed in Russia for the first time in world history. In this work, the results of the characterization of the SWCNT products available in the Russian market are presented and the most promising directions among the technical applications of the materials and products on the basis of SWCNTs are highlighted.