1 research outputs found
Size-Dependent Structure Relations between Nanotubes and Encapsulated Nanocrystals
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