报告题目：Mechanical and Mathematical Properties of Quasicrystals
报 告 人：
报告时间：2018年04月16日 下午15:30
报告地点：机械楼A810
摘要：
The discovery of quasicrystals in 1984 by D. Shechtman, destroyed the fundamental concepts of crystallography which relied on a traditional definition of the crystal as a periodic arrangement of identical unit cells. In his experiments with a rapidly cooled Al-Mn alloy, Shechtman obtained a sharp diffraction pattern with a rotational symmetry incompatible with periodicity. His findings forced the International Union of Crystallography to redefine the notion of the crystal as any solid having discrete diffraction diagram. Quasicrystals are a new class of materials which thanks to their unique properties such as electrical, optical, hardness and nonstick features are finding new and promising applications, e.g. in nonstick coatings, thermal barriers, infrared sensor etc. Two decades after the first publication on quasicrystals, a soft quasicrystal was found in nature and a number of materials including liquid crystals, polymers, nanoparticles and colloids enriched the family of soft quasicrystals, enhancing the potential applications of these quasi-periodic structures.
In my talk I will present a brief history of the discovery of quasicrystals and I will discuss some of the fascinating mechanical and mathematical properties of quasicrystals. In particular I will focus on elastic constitutive relations in which besides the phonon space there is also a contribution from the phason space. I will present the form of the energy density function in some of these quasi-periodic structures. Recent findings of natural quasicrystals will also be mentioned.
报告人简介：
is the professor of Mathematics, Cryptology and Cybernetics at the Military University of Technology, Warsaw, Poland. Previously, he worked as an assistant professor at Institute of Fundamental Technological Research,Polish Academy of Science; as a visiting assistant professor at University of Nebraska Lincoln, USA; and as a visiting associate professor at University of Massachusetts, USA. His research interests are in the propagation and interaction of nonlinear waves in solids, asymptotic methods.
