 lack a regular geometric arrangement of atoms over long distances  Researchers have discovered a new nanometer-scale atomic structure in solid metallic materials known as metallic glasses, filling a gap in understanding of this atomic structure.  Glasses include all solid materials that have a non-crystalline atomic structure. They lack a regular geometric arrangement of atoms over long distances. "The fundamental nature of a glass structure is that the organization of the atoms is disordered - jumbled up like differently sized marbles in a jar, rather than eggs in an egg carton," says Paul Voyles, a University of Wisconsin-Madison associate professor of materials science and engineering and principal investigator on the research.  Researchers widely believe that atoms in metallic glasses are arranged only as pentagons in an order known as five-fold rotational symmetry. However, in studies of a zirconium-copper-aluminum metallic glass, they found there are clusters of squares and hexagons  -  in addition to clusters of pentagons, some of which form chains  -  all located within the space of just a few nanometers. "One or two nanometers is a group of about 00 atoms - and it's how those 00 atoms are arranged with respect to one another that's the new and interesting part," Voyles says.  This could help manufacturers fine-tune such properties of metallic glasses as ductility, the ability to change shape under force without breaking, and formability, the ability to form a glass without crystalizing.  Measuring the atomic structure of glass at 