Atomic movement in glass and simulations awarded
The physical description of how the dynamics of atoms at low temperatures remained a mystery, until a clue dawned on Professor Jain during a boat ride he took to the Isle of Skye, of Scotland’s west coast. Watching the hundreds of jellyfish in the Sea of the Hebrides, he noted that they were not swimming, but rather wiggling without moving very far.
The dynamics of atoms inside glass and computer simulations that make it possible to project the physical properties of materials are the main focuses of the researchers who were recognised with the 2007 Otto SCHOTT Research Award. The researchers Professor Himanshu Jain and Professor Walter Kob were honored with the Otto SCHOTT Research Award valued at €25,000 during the International Congress of Glass 2007 in Strasbourg.
The award is bestowed every other year on an alternating basis with the Carl Zeiss Research Award to recognize exceptional scientific achievements in fundamental research and technology development in the areas of specialized materials, components and systems for applications in optics, electronics, solar energy, health and lifestyle.
Jellyfish model” explains atom movement inside glass
Professor Himanshu Jain (Lehigh University, U.S.A.) has been heading the National Science Foundation’s
»International Materials Institute for New Functionality in Glass (IMI-NFG)« since 2004. He received the award for his outstanding contributions towards promoting the basic understanding of the dynamics of atoms in glass.
Professor Jain’s research focuses on useful functionalities of glass through fundamental understanding, including unique phenomena caused by light and their application in new devices, corrosion of glass in nuclear environments or glasses for use in photonic applications, such as sensors, infrared optics, waveguides, photo- and nano-lithography, to list a few examples.
In the process, he has investigated atomic movement and how it might be influenced by the inherent composition or external factors, such as temperature, electric field, etc. According to existing theories, there are two fundamentally different types of atom movements at ambient temperature: vibration of an atom about its mean position, and long range diffusion wherein a given atom may wander around in the glass structure. An important characteristic of this ion diffusion is that it slows down exponentially with decreasing temperature. If a glass is cooled below ~200 K, ion hopping should effectively freeze. However, nuclear spin relaxation experiments showed that there must be more to ion movement in glass than just vibrations and diffusion.
The dynamics of atoms at low temperatures emerged as a result of his Skye boat trip insight: The ”jellyfish” movements are from a group of atoms which collectively move between different configurations, much like the wiggling of a jellyfish in the ocean. These fluctuations are much slower than typical atom vibrations and depend on the material’s local and medium range structure. The ”jellyfish” movements also occur at room temperature, but become significant only at much higher frequencies. Thus the dynamic properties of glass such as dielectric loss at microwave frequencies are directly predicted from the low frequency studies at low temperatures.
Simulations show dynamics of supercooled fluids
Born in Switzerland, Professor Walter Kob is full professor at the Institute for Physics at the Université Montpellier 2. He has been serving as Director of the Laboratoire des Colloïdes, Verres et Nanomatériaux, since 1995. Professor Kob received the Otto SCHOTT Award for his outstanding work in researching the static and dynamic properties of glasses and supercooled liquids with the help of computer simulations.
The research fields of Professor Kob include the dynamics of supercooled liquids and the nature of glass transformation, the structure and dynamics of gels, sodium silicate melts and glasses and aging of systems made of glass. His research focuses mainly on investigating the static and dynamic properties of disordered systems, such as simple liquids, textured glasses, Potts glasses or polymers, with aid from computer simulations and other statistical mechanics methods. These computer simulations were developed in the last decade in order to obtain insight into the microscopic properties of materials.
Source: http://www.glassonweb.com/news/index/6910/