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The way that atoms move within a class of network-forming ionic glass materials depends upon whether the material consists of an odd or even number of atomic structural units, Illinois researchers have discovered.
NPRE Assistant Prof. Yang Zhang and his graduate student, Ke Yang, co-supervised by Chemistry Prof. Jeffrey S. Moore, have been joined by Dr. Madhusudan Tyagi, a research scientist at the National Institute of Standards and Technology (NIST), in investigating whether these characteristics of species of ionic glass can help them in creating a new intrinsically self-healing material.
The group discovered the phenomenon in observing liquid material as it cooled and formed glass. The Journal of the American Chemical Society recently published their work online.
The odd-even effect previously had been documented in crystalline material, but had not been known in amorphous or glassy material, where the atomic or molecular arrangements are disordered. In solid crystals, the odd-even effect is determined by how the crystals’ atoms are structured or packed. In ionic glasses, which are essentially extremely viscous liquids, the odd-even effect is dynamic and is determined by how the atoms move, Zhang said. The researchers discovered that the material made of an even number of atomic structural units becomes a glass quicker upon being cooled than the material with an odd number of atomic structural units.
The group has been working at the NIST Center for Neutron Research in Gaithersburg, Maryland, to conduct neutron scattering experiments to better understand the microscopic origin of the odd-even effect. The potential for self-healing lies in controlling the atoms’ movement to fill cracks or fractures within a material.
Many self-healing materials rely on additional agents to promote self-healing. Zhang and Moore see a potential for the ionic glass material to achieve repeated self-healing cycles and improved efficiency to adapt to dynamically changing environments. The scientists believe the material could be useful in coatings for residential and industrial use.
In August 2013, Ke Yang's team won the Best Group Presentation Award at the national neutron and X-ray scattering summer school organized by Argonne National Laboratory and Oak Ridge National Laboratory.