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Professor Derek Sinclair

Professor Derek Sinclair

Professor in Materials Chemistry

Department of Engineering Materials
Sir Robert Hadfield Building
Mappin Street, Sheffield, S1 3JD

Telephone: +44 (0) 114 222 5974
Fax: +44 (0) 114 222 5943

Joined the Department in 1999 from the University of Aberdeen where he was a lecturer in the Chemistry Department from 1994-9. Previously, he was a lecturer at the University of Leeds (School of Materials), 1993-4 and a Research Fellow at the Interdisciplinary Research Centre in Superconductivity, Cambridge, 1992-3.

Research interests

Our research is involved with the synthesis and characterisation of oxide-based electroceramics. The properties and applications of many electroceramics depend on the close control of the crystal structure, composition, ceramic microstructure, dopants and dopant (or defect) distribution. Materials of well-defined composition are synthesised and characterised by a variety of diffraction, spectroscopic, microscopic, analytical and thermal techniques. The electrical properties are usually characterised by ac impedance spectroscopy, in preference to dc or conventional fixed-frequency measurements. This multi-technique approach has helped rationalise the composition-structure-property relationships in important electroceramics which include ferroelectrics, solid electrolytes and high temperature superconductors.

In addition to systematic doping studies on established materials, we undertake explorative phase diagram studies and speculative synthetic work on `new´ materials with potentially useful electrical properties. This approach is being used to discover new mixed ionic/electronic conductors, proton conductors, oxide-ion conductors, piezo-, pyro- and ferro-electrics and (high permittivity) microwave dielectrics. Several of these projects are in collaboration with other staff members, including Tony West, Ian Reaney, Neil Hyatt and John Harding.

Impedance spectroscopy is a powerful technique which is being developed to probe electrical imhomogeneities in ceramics, and in particular to study electrode/sample interfaces, surface layers, electro-active grain boundaries, core-shell phenomena within electrically heterogeneous grains, ferroelectricity and ionic conduction. Much of this work has been assisted by advanced data handling techniques, such as combined impedance and modulus spectroscopy, which has been developed in collaboration with Professor Tony West. A variety of electro-materials, commercial devices and porous materials have been characterised successfully including; solid state lithium batteries, positive temperature coefficent of resistance (ptcr)-BaTiO3 ceramics, single crystals of ferroelectric LiTaO3, numerous solid electrolytes, Bi4V2O11 and La9.33(SiO4)6O2, ferro-electric and Pb-free relaxors, Multi-Layer Capacitors (with AVX Ltd, Coleraine), Internal Barrier Layer Capacitors (CaCu3Ti4O12) and pore reduced cement.

Key projects

  • Ferroelectric BaTiO3-based ceramics for multilayer capacitors.

  • High permittivity oxide-based dielectrics for telecommunication applications, eg microwave resonators and filters.

  • Development of non-ohmic devices, eg ptcr-thermistors and Barrier Layer Capacitors.

  • Low Temperature Co-fired Ceramics (LTCC).

  • Pb-free piezoelectrics and recoverable electro-strain materials for actuators.

  • Bi- and Apatite-based oxide-ion conductors as solid electrolytes for sensors and solid oxide fuel cells.

  • Development of Impedance Spectroscopy to characterise electroceramics.

  • Muti-ferroics.

Professional activities and recognition

  • Member of the EPSRC Peer Review College (Functional Materials).

  • Member of the IOM3 Materials Chemistry Committee.

  • Member of the IOM3 Structure of Materials Committee.

  • Editorial Board Member for the Journal of the Ceramic Society of Japan.

Publications uSpace Apply

University of Sheffield
Dept. of Engineering Materials
Sir Robert Hadfield Building
Mappin St.
Sheffield S1 3TD

tel +44 (0)114 2225506
fax +44 (0)114 2226015

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