Some typical PhD-research topics are given below. Although these are self-contained, it often happens that projects are assembled by combining parts of different topics; a considerable degree of flexibility can be used in designing projects tailored to individual students.
Prof.P.Barnes, Dr.O.Leynaud, Dr.S.D.M.Jacques & Dr.J.K.Cockcroft
One of the exciting trends in the last 15 years has been the ability to harness the intense radiation from synchrotron (X-rays) and neutron sources for in situ studies. What we mean by this is that we can now subject a given material to a range of environments which imitate some chemical or physical process while, at the same time, collecting X-ray or neutron diffraction patterns in real time. This has transformed our understanding on how a whole range of chemical reactions and physical transformations take place. In this project we have the possibility, with industrial support, of choosing from a number of projects concerned with the synthesis and performance of materials:
Barnes,P. et al. (1996). "Applied Crystallography Solutions to Problems in
Industrial Solid State Chemistry...ceramics, cements and zeolites",
J. Chem. Soc. Faraday Trans. 92, 2187-2196.
Lalik,E. et al. (2001). "Mechanisms of Reduction of MoO3 to MoO2 Reconciled?",
J. Phys. Chem. B 105, 9153-9156.
Cernik,R.J. et al. (2004) "The new materials processing beamline at...Daresbury",
J. Syncr. Rad. 11, 163-170.
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(2) Structure and properties of pharmaceutical (drug) polymorphs
Dr.J.K.Cockcroft, Mr.M.Vickers, Dr.S.D.M.Jacques, Dr.R.Stephenson, Prof.P.Barnes
Polymorphism in drugs means that a drug compound can exist in more than one structural form. These different forms often exhibit differing properties including, most importantly, shelf life and potency; even further, different polymorphs can be subject to different patent restrictions or even lie outside existing patents. Not surprisingly then, this subject has figured in some well-publicised high court disputes. As a result X-ray diffraction has emerged as a definitive tool for identifying and distinguishing polymorphs. This project will be involved with sorting out polymorphic transformations and structures occurring in various drug systems, with the further possibility of monitoring the crystallisation of drug polymorphs inside a pharmaceutical processor using tomographic methods (see also project No.4).
Anwar,J. et al. (1989) "The Polymorphism of Sulphathiazole",
J.Pharm.Sci. 78, 337-342.
Anwar,J. et al. (1992) "Kinetics of phase transformations in crystals of drug
compounds....", Phase Transitions 39, 3-11.
Chan,F.C. et al. (1999) "Ab Initio Structure Determination of sulfathiazole
polymorph....", J. Appl. Cryst. 32, 436-441.
Jacques,S.D.M. et al. (2004) "An in-process Tomographic Visualisation of
Crystallisation and Polymorphism", submitted to Cryst. Growth& Des.
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(3) The structure and properties of ion-exchanged zeolites
Prof. P.Barnes, Dr.O.Leynaud, Prof. C.R.A.Catlow, Dr.G.Sankar.
Zeolites are important 21st. century materials possessing three-dimensional channels which can be “designed” for specific functions such as molecular sieving, gas-purification and hydrocarbon cracking, or to act as pre-cursor materials for forming novel ceramics or even as negative thermal expansion materials. Our speciality is in studying the synthesis, ion-exchange and dehydration of zeolites using both in situ synchrotron/neutron diffraction and computer-simulation techniques; the example in the references covers a case where we have elucidated the movement of Cs/K/Na-cations in clinoptilolite, an industrially important zeolite used in many environmental applications. This project would involve similar studies on zeolite systems selected for their potential and interesting properties.
Johnson,M. et al. (2003) "Cation-exchange, dehydration and calcination in
clinoptilolite:..", J. Phys. Chem. B107, 942-951.
O'Connor,D. et al. (2004) "Simulating Dehydration...", Molecular Simulation
30, 323-331.
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(4) Synchrotron (X-ray) Tomography of real Materials Processing in action
Prof. P.Barnes, Dr.S.D.M.Jacques, Dr.J.K.Cockcroft, Prof.R.J.Cernik
This research group has invented a novel form of tomography based on synchrotron X-ray diffraction/fluorescence and developments in novel detector systems. It has been applied to problems as diverse as watching materials being mixed in engineering processors, mapping crystallisation as it proceeds inside a seemingly "impenetrable" autoclave cell, and monitoring diffusing of dangerous species through porous environmental media. An enormous range of industrially relevant applications awaits exploitation by this technique.
Barnes,P. et al. (2001) "Tomographic...Imaging of Static and Dynamic Systems",
Nondestr. Test. & Eval. 17, 143-167.
Hooper,D. et al. (2003) "An in situ study of crystallisation...of zeolites",
Phys. Chem. Chem. Phys.,5, 4946 - 4950.
Betson,M. et al. (2004) "Porosity Imaging in Porous Media...",
Transport in Porous Media, 57(2), 203-214.
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(5) In-situ studies of the structure and formation of ceramics and cements
Prof.P.Barnes, Dr.O.Leynaud, Dr.S.D.M.Jacques, Dr.J.K.Cockcroft
High performance ceramics and specialist cements are important functional materials for today. In the Industrial Materials Group we specialise in understanding the synthesis and final structure of such polycrystalline materials. For example the crystallization of zirconia from the hydroxide at high temperature has been studied using the intense X-radiation from synchrotron and neutron sources, and similarly the hydration of oilwell cements under high temperature/pressure (oilwell-like) conditions has been elucidated. In this project the student would be able to use a variety of both in situ X-ray methods (as in project No.1) and support techniques (electron microscopy, computer simulation) to study novel ceramic/cement formulations derived either in-house or with help from the industrial sponsors.
Turrillas, X. et al. (1995) "Synchrotron-related Studies on...Zirconia
Synthesis..., Radiation Phys.& Chem. 45, 491-508.
Jupe,A.C. et al. (2001) "The occupation of Mg in the brownmillerite structure...",
J.Appl.Cryst. 34, 55-61.
Lupo,F. (2004) "Hydrothermal crystallisation of doped zirconia...",
Phys. Chem. Chem. Phys. 6, 1837-1841.
Colston,S.L. et al. (2004/5) "An in situ Synchrotron...study...Oilwell Cement...",
Cement & Concr. Res., in press.
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(6) Exploiting low temperature powder diffraction
Dr.J.K.Cockcroft, Dr.R.Stephenson, Mr.M.Vickers, Prof.P.Barnes, Prof.P.F.McMillan
Many materials (e.g. pharmaceutical products, molecular solids, silicon clathrates) display interesting phase transitions or thermal expansion properties on cooling. The nature of such transformations (e.g. order/disorder) can be studied using low temperature powder diffraction with the bonus that the structural atomic positions become much more well defined at low temperatures. In this project the student would use low temperature (to 4 K) powder diffractometers, both newly-designed in-house versions or those at neutron/synchrotron sources. The data would be used to perform Rietveld structure refinements, in some cases combining the X-ray and neutron data when additional information can be extracted (e.g. position of hydrogen atoms; order/disorder parameters).
Vogt et al. (1994) "The crystal and molecular structures of rhenium heptafluoride",
Science 263, 1265-1267.
Hutchings,P. et al. (2004/5) "The thermal expansion properties of a silicon
clathrate", in preparation.
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