Nanoparticles can act like liquid on the outside, crystal on the inside

A surprising phenomenon has been found in metal nanoparticles: They appear, from the outside, to be liquid droplets, wobbling and readily changing shape, while their interiors retain a perfectly stable crystal configuration.

The research team behind the finding, led by MIT professor Ju Li, says the work could have important implications for the design of components in nanotechnology, such as metal contacts for molecular electronic circuits.

The results, published in the journal Nature Materials, come from a combination of laboratory analysis and computer modeling, by an international team that included researchers in China, Japan, and Pittsburgh, as well as at MIT.

The experiments were conducted at room temperature, with particles of pure silver less than 10 nanometers across -- less than one-thousandth of the width of a human hair. But the results should apply to many different metals, says Li, senior author of the paper and the BEA Professor of Nuclear Science and Engineering.

Silver has a relatively high melting point -- 962 degrees Celsius, or 1763 degrees Fahrenheit -- so observation of any liquidlike behavior in its nanoparticles was "quite unexpected," Li says. Hints of the new phenomenon had been seen in earlier work with tin, which has a much lower melting point, he says.......

Ref : http://dx.doi.org/10.1038/nmat4105

Nanoparticles can act like liquid on the outside, crystal on the inside