Weird Metals - Modulations within Hosts within Guests
Recent angle-dispersive diffraction studies of group II and group V metals at the SRS have revealed a remarkable new class of elemental crystal structure. The composite structures observed in Ba-IV, Sr-V, Bi-III and Sb-II comprise a tetragonal 'host' structure with channels along the c axis. Within these channels are chains of atoms which form one or more interpenetrating 'guest' structures that are incommensurate with the host along c. This composite structure has been dubbed ''the weirdest known atomic structure of any pure metal''.
In our initial studies of Sb-II and Bi-III we identified a number of very weak peaks that could not be explained by the composite host-guest structure. And studies at ESRF revealed a greater number of such reflections. We have now identified these peaks as coming from a modulation of the host structure produced by its interaction with the guest structure.
In this talk I will review the most recent results on the composite host-guest structures of Bi and Sb, and describe new analysis of the modulation of the host structure. I will also review some recent results on the host-guest structure of Rb-IV.
This is a weekly series of informal talks given primarily by members of the soft condensed matter and statistical mechanics groups, but is also open to members of other groups and external visitors. The aim of the series is to promote discussion and learning of various topics at a level suitable to the broad background of the group. Everyone is welcome to attend..