Frameworks, flexibility, and frustration

Lecture overview

The use of flexible building units in the design of molecular frameworks yields crystalline materials with long-range structural periodicity but which retain some structural degrees of freedom. What results is an interesting and unusual crystal dynamics normally associated with low-dimensional materials, including the existence of highly-structured diffuse scattering patterns in diffraction images and a predisposition for complex phase transitions. This talk will explore the interplay between geometry and structural flexibility in these materials, with a particular emphasis on the emergence of unusual and useful physical properties: negative thermal expansion, negative compressibility, and temperature/pressure-induced amorphisation. The talk concludes with a discussion of the emerging parallels between the low-energy dynamics of framework materials and spin arrangements in frustrated magnets.

Biography

An undergraduate at the University of Sydney, Andrew read chemistry and pure mathematics for his first degree. He subsequently obtained PhDs in inorganic chemistry (with Cameron Kepert, Sydney) and mineral physics (with Martin Dove, then at Cambridge). While a graduate student at Cambridge, Andrew was elected to a Trinity College Junior Research Fellowship in materials science. He held this post for five years, intermitting briefly to take up a Visiting Fellowship at the Australian National University (with Ray Withers). Andrew moved to Oxford in 2009 as a University Lecturer in inorganic chemistry.