Date: Wednesday 10th of October 2018, 14:00.
Location: INB3305 (Isaac Newton Building).
‘Quasicrystal formation in soft matter’
by Andrew J. Archer, Department of Mathematical Sciences, Loughborough University, Loughborough, UK.
In the early eighties quasicrystals (QCs) were first observed by Shechtman in metallic alloys, leading to the award to him of a Nobel prize in 2011. Regular crystals are ordered arrangements of atoms or molecules with rotation and translation symmetries, having a discrete X-ray diffraction pattern, or equivalently, a discrete spatial Fourier transform. In contrast, QCs lack the lattice symmetries of regular crystals, yet they still have discrete Fourier spectra. QCs can be quasiperiodic in all three dimensions (usually with icosahedral symmetry), or can be quasiperiodic in two (or one) directions while being periodic in one (or two). The vast majority of the QCs discovered so far are metallic alloys with at least two components (e.g., Al/Mn or Cd/Ca). However, QCs have recently been found in nanoparticles, mesoporous silica, and soft-matter systems. In this talk I will introduce the subject and present our theoretical work done over the last few years that has deepened our understanding of how soft matter QCs can form and what makes them energetically stable.