Variable temperature crystallography on new fast Li ion conductors

We hope to utilise variable temperature neutron diffraction to understand the structural chemistry in two new Li-rich ionic conductors and relate them to known families of fast ion conductors. Activation barriers associated with bulk ionic transport are determined by the coordination environments local to the Li ions and the pathways that exist between them; accurate structural characterisation is therefore needed to understand the transport mechanisms. This is possible only through analysis of neutron powder diffraction due to the weak X-ray scattering of lithium. We will locate the lithium positions in these materials and understand the extent of order/disorder which is key to ionic transport. Samples are ready to be measured and have been characterised using synchrotron X-ray diffraction (I11), measurement of thermal behaviour, composition and ionic conducting properties.