A Squeezable Nanocrystal Film that Switches
Between Metal and Insulator Properties
A captured still from a camcorder of a compressed film where
you can see a metallic sheen.
The uncompressed film has the properties of an insulator. Notice that the shininess is gone.
An electron microscope image of the film, showing a hexagonal
arrangement of silver nanocrystals. The electron microscope can only image
the metal nanocrystals, not the organic molecules to which they are attached. The
molecules act like little springs when the film is compressed,
decreasing the separation between nanocrystals and
causing the film to switch from insulating to metallic properties.
This work is described in a paper by C.P. Collier, R.J. Saykally, J.J. Shiang,
S.E. Henrichs, and J.R. Heath in the 27 September 1997 issue of
Science. Thanks to
Pat Collier for supplying figures and captions. For more information,
you can contact Jim Heath's experimental group at UCLA by writing to heath@chem.ucla.edu.
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