Disordered Materials Professor Richard Welberry

Many important materials such as ceramics, superconductors, catalysts, electro-optical materials and minerals owe their special properties to the disorder in their structure. This disorder causes diffuse X-ray scattering which can be probed using synchrotron X-rays to reveal details about the material’s nanoscale structure and dynamics.

Our research involves the development of methods and strategies to measure, interpret and analyse diffuse scattering. The methods being developed will enhance our detailed understanding of the relationships between structure and properties in all kinds of materials and help promote the design of new materials.

Of key importance in our current work is the investigation of the role played by local strain in determining the nano-scale structure of disordered materials.

Current research activities

Study of flexible organic molecules

Diffuse X-ray scattering is being used to analyse how the flexibility of certain classes of organic molecules influences their ability to form well-ordered crystal structures. Diffuse scattering gives information about how neighbouring molecules interact with each other - information not available from conventional crystallography. Such information may provide the key to why some compounds are difficult to crystallize while others have a tendency to produce different polymorphic forms. The latter is of particular importance in the pharmaceutical industry.

Non stoichiometric inorganic materials

We are studying a range of non-stoichiometric inorganic materials with a view to understanding how the complex disorder present is of importance in explaining their physical properties (e.g. ferro-electricity, ferro-elasticity, ionic conductivity, etc.). Included in this category are a number of important ceramic materials such as stabilised zirconias, wüstite and mullite.

Quasicrystals

Quasicrystals are interesting because they possess symmetries which are forbidden in classical crystallography. Although it is now almost 20 years since their first discovery in 1984 the structure of quasicrystals and their relationship to normal crystal phases continues to present great challenges for the structural scientist. We are applying our methods developed for disordered crystals to try to understand the disorder phenomena that are present in these novel materials.

Annual Research Report   (PDF format)

Group members

Academic Staff:
Professor Richard Welberry (Leader)   |   Dr Eric Chan   |   Dr Darren Goossens

PhD Students:
Andrew Beasley

Technical and General Staff:
Dr Aidan Heerdegen

Key publications

1. Welberry T.R, Goossens D.J, Edwards A.J, & David, W.I.F. Diffuse X-ray scattering from benzil, C₁₄H₁₀O₂: analysis via automatic refinement of a Monte Carlo model. Acta Crystallographica A 57, 101-109 (2001).
2. Welberry, T.R. Diffuse X-ray scattering and models of disorder. IUCr Monographs on Crystallography Oxford University Press, 279pp, (2004).
3. Welberry, T.R. and Goossens, D.J. Chemical origin of nanoscale polar domains in PbZn_1/3Nb_2/3O₃. Physical Review, 74, 224108 (2006).
4. Welberry T.R., Sing B. Deformed Penrose tilings Philosophical Magazine, 87 , 2877-2886, (2007).
5. Thomas L.H, Welberry, T.R, Goossens D.J, Heerdegen A.P, Gutmann M.J, Teat S.J, Lee P.L, Wilson C.C, Cole J.M, Disorder in pentachloronitrobenzene, C₆Cl₅NO₂: a diffuse scattering study. Acta Crystallographica B, 63, 663-673, (2007).

>>more publications

Richard Welberry is a Professor in the RSC. He is a former President of the Society of Crystallographers in Australia and New Zealand (SCANZ), is a Co-editor of the Journal of Applied Crystallography and Crystallography Reviews and is a member of the Commission on Journals of the International Union of Crystallography.

private web page: Richard Welberry group photos

Professor T R Welberry Research School of Chemistry, Building 35 Australian National University Canberra ACT 0200 AUSTRALIA Ph: +61 2 6125 4122 Fx: +61 2 6125 0750 E-mail: welberry@rsc.anu.edu.au