84 5 One- and Two-Dimensional Nanoparticles
Figure 5.5 Electron micrograph of a CuFe 2 O 4 platelet with the (111) plane at the top surface.
The hexagonal shape deviates from the expected cubic one. It is obtained by adding
surfactants to the solution to precipitate the ferrite [3]. (Reproduced with permission by
Elsevier.)
25 nm
Studying the electron micrographs in Figures 5.3a and 5.5, one observes
extremely smooth surfaces. This is not surprising, as any imperfection of the faces
enlarges the surface and, therefore, the surface energy increases.
One- and two-dimensional features, such as nanotubes and nanoplates, are
often related to materials crystallizing in layered structures. Typical examples are
BN, WS 2 , MoS 2 , WSe 2 , MoSe 2 , and, most important, carbon as graphite. In most
cases, these are structures, where the layers are held together with van der Waals
Figure 5.4 Six cubes, within each one a lattice plane is plotted together with the Miller
indices.
z
y
x
z
y
x
z
y
x
z
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x
z
y
x
z
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x
(001)
(110)
(111)