406
14 Nanostructures
Fig. 14.8 Critical radius r c
above which an infinitely
thick layer with misfit
grows coherently on a
cylindrical nanowire
(relaxation by 60 ◦
dislocations, b = 0.4 nm,
ν = 1/3). Adapted
from [1357]
Fig. 14.9 a SEM image of
an ensemble of ZnO
nanobelts. b HRTEM
image of a single ZnO
nanobelt, viewing direction
is [00.1]. The inset shows
the diffraction pattern.
Adapted from [1358],
reprinted with permission,
©2004 AIP
Fig. 14.10 a Bright field
and b dark field TEM
image of a ZnO nanoring
formed by the ‘slinky’-like
growth of a nanobelt. c
SEM image of an open
ZnO nanospiral. The insets
in (a, c) show
schematically the surface
charge distribution.
Adapted from [1359],
©2006 IOP
14.2.4 Nanobelts
A number of belt-shaped nanostructures has been reported [1347]. These are wire-like, i.e. very long in
one dimension. The cross-section is rectangular with a high aspect ratio. In Fig. 14.9a ZnO nanobelts
are shown. The wire direction is [2 ¯
1.0]. The large surface is (00.1), the thickness of the belt extends
in [01.0]-direction. High resolution transmission microscopy (Fig. 14.9b) shows that these structures
are defect-free. The pyroelectric charges on the ZnO (0001) surfaces (Sect. 16.2) lead to the formation
of open (Fig. 14.10c) spirals. Closed spirals (Fig. 14.10a) occur if the short dimension is along [00.1]
and alternating charges become compensated in a ‘slinky’-like ring (Fig. 14.10b).
14 Nanostructures
Fig. 14.8 Critical radius r c
above which an infinitely
thick layer with misfit
grows coherently on a
cylindrical nanowire
(relaxation by 60 ◦
dislocations, b = 0.4 nm,
ν = 1/3). Adapted
from [1357]
Fig. 14.9 a SEM image of
an ensemble of ZnO
nanobelts. b HRTEM
image of a single ZnO
nanobelt, viewing direction
is [00.1]. The inset shows
the diffraction pattern.
Adapted from [1358],
reprinted with permission,
©2004 AIP
Fig. 14.10 a Bright field
and b dark field TEM
image of a ZnO nanoring
formed by the ‘slinky’-like
growth of a nanobelt. c
SEM image of an open
ZnO nanospiral. The insets
in (a, c) show
schematically the surface
charge distribution.
Adapted from [1359],
©2006 IOP
14.2.4 Nanobelts
A number of belt-shaped nanostructures has been reported [1347]. These are wire-like, i.e. very long in
one dimension. The cross-section is rectangular with a high aspect ratio. In Fig. 14.9a ZnO nanobelts
are shown. The wire direction is [2 ¯
1.0]. The large surface is (00.1), the thickness of the belt extends
in [01.0]-direction. High resolution transmission microscopy (Fig. 14.9b) shows that these structures
are defect-free. The pyroelectric charges on the ZnO (0001) surfaces (Sect. 16.2) lead to the formation
of open (Fig. 14.10c) spirals. Closed spirals (Fig. 14.10a) occur if the short dimension is along [00.1]
and alternating charges become compensated in a ‘slinky’-like ring (Fig. 14.10b).