We welcome this week’s speaker in the departmental seminar series:
Professor John Evans, Department of Chemistry, Durham University
“Put Your Trust in Powder: New Methods for Probing Structure-Property Relationships in Materials”
The primary thrust of my research group is in the synthesis and characterisation of new inorganic materials. We aim to design, synthesise and prepare materials with exploitable structural, optical, electronic and magnetic properties. One of the key tools that we use to guide our research is powder diffraction. In this lecture I’ll try and show how state-of-the-art powder diffraction studies can give enormous insight into the behaviour of materials in the solid state and the transitions they undergo. I’ll show how powder diffraction can be used to give both “conventional” information about the composition of multi-phase samples and their crystallographic structure, as well as “unusual” information such as mechanistic insight on how materials transform and information about the kinetics and energetics of such processes.
I’ll illustrate the ideas with a range of examples from our work, predominantly on materials that show the unusual property of negative thermal expansion and which contract in volume on heating. I’ll try to emphasise how the same methodologies can be readily applied to mineralogy/earth science examples.
I’ll discuss briefly two new methods we’ve developed in the group which I believe will be of particular interest to the Earth Sciences community: “Parametric Rietveld Refinement” and “Distortion Mode Rietveld Refinement” [1, 2].
[1] G.W. Stinton, J.S.O. Evans, Journal of Applied Crystallography, 2007, 40, 87–95.
[2] S. Kerman, B.J. Campbell, K.K. Satyavarapu, H. T. Stokes, F. Perselli and J. S. O. Evans, Acta Cryst., 2013, A68, 222–234.
https://www.dur.ac.uk/chemistry/staff/profile/?id=180
http://community.dur.ac.uk/john.evans/