Hydrothermally synthesized one-dimensional and two-dimensional nanocrystals
of VO2 undergo phase transition around 65?C, where temperature and mechanism
of phase transition are dependent on dimensionality of nanocrystals. Both
nanocrystalline samples exhibit depression of phase transition temperature
compared to the bulk material, the magnitude of which depends on the
dimensionality of the nanocrystal. One-dimensional nanoribbons exhibit lower
phase transition temperature and higher values of apparent activation energy
than two-dimensional nanosheets. The phase transition exhibits as a complex
process with somewhat lower value of enthalpy than the phase transition in
the bulk, probably due to higher proportion of surface atoms in the
nanocrystals. High values of apparent activation energy indicate that
individual steps of the phase transition involve simultaneous movement of
large groups of atoms, as expected for single-domain nanocrystalline
materials.
Influence of dimensionality on phase transition in VO2 nanocrystals
