ИСТИНА

General methodology for the synthesis of one-dimensional crystals inside the inner channels of single-wall carbon nanotube have been developed and optimized. The approaches of the capillary condensation of vapors and capillary filling by fluids were used for the introduction of matter and crystal formation within the channels of SWNTs. The experiments were carried out using single-walled carbon nanotubes with diameters of 1.2-1.6 nm obtained by catalytic arc-discharge method; 3d-metal halides AXn (where A - Mn, Fe, Co, Ni, Cu, Zn, Ag, Pb, Sn, Cd; X - Cl, Br, I, S, Se, Te) were utilized as guest compounds for composites. The choice of those was made to cover a wide range of work functions (3.5 to 6 eV), thus allowing to carry out both donor and acceptor doping of SWNTs. The structure of one-dimensional crystals formed in internal channels SWNT composites was solved using high resolution transmission electron microscopy. It was observed that the length of the nanocrystals extends over tens to hundreds of lattice parameters, while maintaining uniformity of structure within the observed fragments. Structural models were first proposed for several one-dimensional crystals of metal halides formed in the channels of SWNT. The structure of the crystals was confirmed by image simulation, giving a good agreement with the experimentally observed projections. The relationship between the degree of crystallinity of the obtained metal halide nanocrystals in SWNT channels, lengths of metal-halogen bonds and halogen ion radius was established. It is shown that the structure and crystallinity of the guest compounds in the internal channels of nanotubes is dictated by inconsistency between the parameters of the unit cell of the crystal and an inner diameter of the tube. It was shown that filling of nanotubes of different diameters with the same compound can lead to the implementation of various types of structures. Partial coordination of intercalated compounds by SWNT walls was established by EXAFS and the high angle angular dark field (HAADF) HRTEM data. According to the optical absorption, valence band photoemission spectroscopy and work function measurements, a Fermi level (FL) shift as compared with the initial value for the nanotube and a corresponding charge transfer from the nanotube to the 1D crystal is observed for composites. It was shown that both the chemical nature and the crystal structure of 1D crystal govern interaction between the embedded compounds and SWNT walls. The X-ray absorption and emission spectra revealed a new localized energy level composed of the carbon 2рz and 3d (4d) orbitals of the metal ion to form collective electron states, which in line with the structural HAADF HRTEM and EXAFS data. The decrease in the electron density on the walls of the nanotubes causes a change in the work function, which results in a shift of all components in the x-ray photoelectron spectra. The efficiency of transfer of electrons to the localized state depends on an electron affinity on crystal anion and is strongly correlated with the energy gaps between Van Hove singularities. This effect demonstrates the need for describing the electronic structure of the composites beyond the model of rigid band structure. The stoichiometry of nanocrystals established by local microanalysis deviates from those of bulk materials, which indicates the presence of chemical bonding of the embedded nanocrystals with the walls of the nanotubes.