Event

Amorphous materials have no long-range order, but there are ordered structures at short-range (2-5 Å), medium-range (5-20 Å), and even longer-length scales. While regular and semiregular polyhedra are often identified as short-range order in amorphous materials, the nature of the medium-range order has remained elusive. Because of the disorder, the dynamics also become far more complicated.  For example, the vibrational spectrum of glasses shows an excess density of states. This is known as the Boson Peak and has been found to be a ubiquitous feature of amorphous materials. In this talk, I will present recent studies of metallic glass using neutron and synchrotron X-ray scattering. The development of medium-range order in driving liquid-to-liquid phase transitions will be highlighted. For the dynamics, the momentum dependence of the inelastic scattering intensity reveals spatial correlation at different time scales. The role of local structure fluctuations will be discussed