Sinclair, Derek C - University of Sheffield - Department of Materials Science and Engineering

个人简介

Derek was appointed to the academic staff at the University of Sheffield in 1999 as a Lecturer in Functional Materials following from Lecturer appointments in the Department of Chemistry, University of Aberdeen (1994-99) and the Department of Materials Science, University of Leeds (1993-94). He obtained his BSc (1st Class Honours) and PhD (supervised by Professor Tony West) in Chemistry at the University of Aberdeen and held post-doctoral research appointments at the University of Aberdeen (with Profs Tony West and John Irvine) and the Interdisciplinary Research Centre for Superconductivity at the University of Cambridge (with Prof Paul Attfield), before joining the academic staff at Leeds in 1993. Derek is a recognised for his ability to probe the structure (crystal and defect)-composition-microstructure-property relationships of a wide range of functional oxides, spanning from superconductors to dielectrics via mixed conductors and solid electrolytes.

研究领域

Our research is involved with the synthesis and characterisation of oxide-based functional ceramics. The properties and applications of many functional ceramics 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 is backed up with atomistic modelling (defect chemistry) and finite element modelling (electrical microstructure) to rationalise the composition-structure-property relationships in important functional ceramics which include dielectrics, solid electrolytes, mixed conductors and thermoelectrics. 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, (high permittivity) microwave dielectrics and thermoelectrics. Several of these projects are in collaboration with other MS&E staff members, including Tony West, Ian Reaney, John Harding, Colin Freeman and Julian Dean. We also collaborate with Rachael Elder and Ray Allen from Chemical & Biological Engineering on solid oxide electrolysis cells as part of an EPSRC Programme Grant on Carbon Capture and Utilisation (4CU). Impedance spectroscopy is a powerful technique which is being developed to probe electrical inhomogeneities 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 Tony West. Recently we have developed a finite element code to simulate impedance spectroscopy data (with Julian Dean and John Harding) for three dimensional ceramic microstructures which allows comprehensive treatment of a full three-dimensional granular representation of ceramic microstructure without the requirement for equivalent circuits based on the Brickwork layer model or the introduction of constant phase elements to describe any nonideality of the impedance response. A variety of electro-materials, commercial devices and porous materials have been characterised successfully including; solid state lithium batteries, positive temperature coefficient of resistance (ptcr)-BaTiO3 ceramics, single crystals of ferroelectric LiTaO3, numerous solid electrolytes, Bi4V2O11, La9.33(SiO4)6O2 and (Na,Bi)(Ti, Mg)O3, ferro-electric and Pb-free relaxors, BaTiO3-based Multi-Layer Capacitors (with AVX Ltd, Coleraine), Internal Barrier Layer Capacitors (CaCu3Ti4O12) and pore reduced cement.

近期论文

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M. Li, M.J. Pietrowski, R.A. De Souza, H. Zhang, I.M. Reaney, S.N. Cook, J.A. Kilner and D.C. Sinclair, A family of oxide ion conductors based on the ferroelectric perovskite Na½Bi½TiO3, Nature Materials, 13 (2014) 31-35. [DOI: 10.1038/nmat3782] C. L. Freeman, J.A. Dawson, H-R. Chen, L. Ben, J.H. Harding, F.D. Morrison, D.C. Sinclair and A.R. West, Energetics of donor-doping, metal vacancies and oxygen-loss in A-site rare-earth-doped BaTiO3, Advanced Functional Materials, 23 (2013) 3925-3928 [DOI: 10.1002/adfm.201203147] M. Hernando, L. Miranda, A. Varela, K. Boulahya, S. Lazar, D. C. Sinclair, J. M. González-Calbet and M. Parras, Direct Atomic Observation in Powdered 4H-Ba0.8Sr0.2Mn0.4Fe0.6O2.7, Chemistry of Materials, 25 (2013) 548-554 [DOI: 10.1021/cm303609r] C. L. Freeman, J. A. Dawson, J. H. Harding, L.-B. Ben and D.C. Sinclair, The Influence of A-site rare earth ion size in controlling the Curie temperature of Ba1 − xRExTi1 − x /4O3, Advanced Functional Materials, 23 (2013) 491-495. [DOI: 10.1002/adfm.201201705] G. He, R. H. Elder, D. C. Sinclair, R. W. K. Allen, High temperature oxygen separation for the sulphur family of thermochemical cycles - Part II: Sulphur poisoning and membrane performance recovery, International Journal of Hydrogen Energy, 38 (2013) 785-794. [DOI: 10.1016/j.ijhydene.2012.10.088] I. M. Reaney, I. MacLaren, L. Wang, B. Schaffer, A. Craven, K. Kalantari, I. Sterianou, S. Miao, S. Karimi and D. C. Sinclair, Defect chemistry of Ti-doped antiferroelectric Bi0.85Nd0.15FeO3, Applied Physics Letters, 100 (2012) 182902. [DOI: 10.1063/1.4705431] S. Krohns, P. Lunkenheimer, S. Meissner, A. Reller, B. Gleich, A. Rathgeber, T. Gaugler, H. U. Buhl, D. C. Sinclair and A. Loidl, The route to resource-efficient novel materials, Nature Materials, 10 [12] (2011) 899-901. [DOI:10.1038/nmat3180] M. Li, A. Feteira, M. Mirsaneh, S. Lee, M.T. Lanagan, C.A. Randall and D. C. Sinclair, Influence of Non-stoichiometry on Extrinsic Electrical Conduction and Microwave Dielectric Loss of BaCo1/3Nb2/3O3 Ceramics, Journal of American Ceramic Society, 93 [12] (2010) 4807-4905. [DOI: 10.1111/j.1551-2916.2010.03999.x] M.C. Ferrarelli, D. Nuzhnyy, D.C. Sinclair and S.Kamba, Soft-mode behaviour and incipient ferroelectricity in Na½Bi½Cu3Ti4O12, Physical Review, B81 (2010) 224112. [DOI: 10.1103/PhysRevB.81.224112] M.C. Ferrarelli, D.C. Sinclair, A.R. West, H.A. Dabkowska, A. Dabkowski and G.M. Luke, Comment on the origin(s) of the giant permittivity effect in CaCu3Ti4O12 single crystals and ceramics, Journal of Materials Chemistry, 19 (2009) 5916-5919. [DOI: 10.1039/b910871h]