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Ferroelectrics & Crystallography Group

Research is carried out by the group, led by Professor Pam Thomas, on the fundamental physics of a wide range of ferroelectric crystals, including environmentally-friendly lead-free piezoelectrics, particularly those based on sodium bismuth titanate (NBT), and on novel optical properties revealed by the lithium niobate-tantalate solid solution. The group also continues its fundamental studies of non-linear optical crystals with tailored periodic domains for frequency conversion, which we study using specialised coherent X-ray imaging techniques in collaboration with Professor Jose Baruchel's group and ESRF, and is embarking on an investigation of the fundamental physics of novel multiferroic fluorides together with Warwick's Resonance Group and collaborators (Professor Jens Kreisel) at INPG Grenoble. The aim is the understanding of physical properties and phase transitions from the basis of structure in the most general sense, i.e. on the average crystallographic, local and “nano” scales. An approach is adopted in which relevant techniques are carefully chosen for the investigation of the problem at hand, frequently combining synchrotron and laboratory-based high-resolution X-ray diffraction, diffuse scattering and imaging, dielectric and optical measurements, neutron diffraction and NMR.

Professor Pam ThomasProfessor Pam Thomas has been a member of staff in the Department of Physics at the University of Warwick since 1990 and a full professor since 2005. She was educated at Oxford University, where she took an BA (Hons) in Physics and a DPhil on the subject of Optical Activity in Crystals in the Physical Crystallography Group of the Clarendon Laboratory. Pam is head of the Ferroelectrics and Crystallography Group, and is also responsible for the strategy and running of the inter-departmental X-ray Diffraction Facility within Physics, which is shortly to be housed in bespoke-designed laboratories in the new £25M Materials and Analytical Sciences building. The X-ray Diffraction Suite has benefitted enormously from investment under the project Advanced Materials 1: Creating and Characterising Next-Generation Materials, supported by Advantage West Midlands and the European Regional Development Fund, started under the Birmingham Science City initiative in 2008.

Pam’s research expertise is in the crystallography, structure and related properties of ferroelectric, piezoelectric and nonlinear optical crystals, ceramics and thin-films. She has an extensive publication record on perovskites and related materials (e.g. PZT, BaTiO3, Na0.5Bi0.5TiO3, LiNbO3, LiTaO3) and on the members of the KTiOPO4 (KTP) family of materials as well as a host of papers on the application of novel X-ray and optical techniques to a range of functional materials from gallium nitride to carbon nanotubes. She has several patents either granted or in the application stage, the latest of which concerns a zero-birefringence LiTaO3 variant for remote optical sensing (see here).

Pam is a frequent user of central facilities including synchrotron radiation at ESRF (France) and Diamond (UK); neutron diffraction at ILL (France) and ISIS (UK) and has served several terms on the beam allocation panels, including a period as Chair of the ESRF Panel on Materials Engineering. She is also a member of the Commission of Inorganic and Mineralogical Crystallography for the International Union of Crystallography and is on the local and programme committees of the European Crystallography Meeting, which will be held at Warwick in 2013 in the Centenary Year of W.L. and W.H. Braggs’ Nobel-prize winning research on X-ray crystallography.

From October 2009-2011, Pam was the Director of the Science City Research Alliance (SCRA) for the Universities of Birmingham and Warwick. This involved leadership of the cross-disciplinary scientific programme around a multi-million pound investment in research Infrastructure and people in the two universities by AWM/ERDF and from HEFCE, whose £10M grant under the Strategic Development Fund scheme supports a College of SCRA Fellows. Pam took up the role of the Chair of the Faculty of Science at Warwick in September 2011, with responsibilities towards more than 20 Departments and Research Centres of various types. She retains her mentoring role for the College of SCRA Fellows until 2014 in addition to her professorial role as a senior member of staff in Physics.

NEWS

21/07/2016

New insight into the self-organised domains in BaTiO3 single crystals. An X-ray topography experiment and Optical Birefringence study are published in Phys. Rev. B.

04/11/2014

Our latest PZT structural study, published in Nature Communications is highlighted at Phys.org. It provides the first experimental evidence for the missing phase boundary in PZT.

Older news

In collaboration with Oxford University a reproducible and low-cost method of modifying the optical properties of crystalline Lithium Tantalate enables highly accurate temperature readings, down to individual milli-kelvins, over a broad range of temperatures: -120°C to +680°C. More details here.

Selected images of optical birefringence recorded during heating of dodecasil-3C crystals from our collaboration with Richard Walton's group chosen to be the 2011 Journal of Applied Crystallography cover image.

JAC Cover image 2011

New insight into the structure of PZT published in Phys. Rev. Lett. using Neutron diffraction on single crystals which have been grown for the first time. More information can be found here.