Conventional thinking says that a block of salt can’t stretch, but researchers from Sandia National Laboratories and the University of Pittsburgh are saying they aren’t so sure anymore.
In an article published in Nanoletters, members of the group describe how they were poking around a small piece of salt with an interfacial force microscope when they noticed that salt stuck to the tip of the IFM and clung with it even as the tip was moved away from the main piece of salt. They learned they could stretch the salt nanowire-like tendrils to lengths from 580 nm to 2,191 nm.
“It’s not supposed to do that,” said Sandia principal investigator Jack Houston in a SNL news release. “Unlike, say, gold, which is ductile and deforms under pressure, salt is brittle. Hit it with a hammer, it shatters like glass.”
Houston and the others believe that at the interface between the IFM tip and the salt surface, salt molecules formed a ductile meniscus. Houston said he thinks the reason this is occurring is that because surface molecules don’t have an atomic lattice above them, they are free to be more mobile than interior salt molecules.
The discovery may have application in desalination systems. It may also provide insight on sea salt aerosols. These aerosols are linked to cloud nucleation and lead to environmental problems, such as smog, ozone destruction and asthma.