Controlling the size, shape and structure of nanocrystals is technologically important
because of the strong effect of size and shape on optical, electrical, and catalytic
properties. Monodispersed nanocrystals of copper oxide were prepared by the
precipitation–pyrolysis method. By controlling the starting materials, reactive
concentration and annealing temperature, we can obtain spherical monodispersed CuO
nanocrystals of different sizes or rodlike CuO nanocrystals. The particle sizes
of CuO monodispersed nanocrystals can be tuned in the range between and 30 nm. The products have been characterized by x-ray diffraction, transmission
electron microscopy, high-resolution transmission electron microscopy and the UV–visible
absorption spectrum. The absorption spectra of CuO nanocrystals show clear evidence of
the quantum size effect. The possible formation mechanism of monodispersed CuO
nanocrystals is discussed.
The mechanical properties at the interfaces of TiC x /NiAl composites with four different C/Ti ratios fabricated by pressureless melt-infiltration processing were investigated using the nanoindentation technique. We find that the nanohardness and the elastic modulus from the TiC x phase to the NiAl phase have a gradient distribution. Both the elastic modulus and nanohardness at the interface reached higher values at x = 0.75. The topography of the sample was analysed by scanning force microscopy.
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