Physicists from Campinas have found a new shape of nanowires: square and hollow. Examined using an atomic resolution electronic microscope, which is so powerful that it shows atoms moving, these ultra-minute wires have the smallest hollow square-based atomic structure so far described, with just four silver atoms. These structures must form spontaneously when the nanowire is stretched like chewing gum being pulled, according to Maureen Lagos and physicists from Unicamp and the National Synchrotron Light Laboratory (LNLS). These minimal atomic arrangements may be a way for the nanowires to absorb the intense deformation that makes them close to something like a nano-accordeon and allows them to be tightly stretched without breaking, explains Daniel Ugarte, a researcher from Unicamp and the LNLS and one of the coordinators of the study, which was published in Nature Nanotechnology in January. “We hope that these structures also form in the copper wire that is likely to constitute electrical conductors in nanocircuits in the future”, says Ugarte. If they do form, copper nanowires should gain elasticity and resistance.