Dr Nik Reeves-McLaren

BSc (Hons) PhD
X-ray Diffraction Small Research Facility Manager
Departmental Radiation Protection Supervisor

Address:
Department of Materials Science and Engineering
Sir Robert Hadfield Building
Mappin Street, Sheffield, S1 3JD

Telephone: +44 (0) 114 222 6013
Fax: +44 (0) 114 222 5943

Email: n.reeves@sheffield.ac.uk
Website: http://uspace.shef.ac.uk/community/xrdlab

Nik Reeves-McLaren obtained his BSc (Hons) in Chemistry with New Materials Technology from The University of Aberdeen in 1999, before moving to The University of Sheffield where he undertook a PhD on "Novel Cathode and Anode Materials for Rechargeable Lithium-ion Batteries", which was completed in 2003. He was then appointed as X-ray Diffraction Laboratory Manager in November 2003.

Research interests

My research interests broadly cover ceramic materials. These can be summarised as follows:

• Crystal structure solution of new ceramic oxide phases. Nik looks at new materials whose crystallographic structures have not previously been identified. Ab initio structure solution is conducted, using the GSAS (EXPGUI) and Topas packages, to identify and understand these structures, and to discover what properties the materials may have.
• X-ray absorption spectroscopy (XAS) of electroceramics. Projects are ongoing where XAS techniques are applied in the study of valence state and local coordination environment of transition metals in a wide variety of structure types in electroceramic materials. Nik is responsible for all data collection and analysis within his research group.
• Structure-property relations in spinel oxides. Spinel-structured materials featured heavily in Nik´s PhD project, and continue to be a major focus of research activity. Particular interests include the study of order-disorder phenomena and reversible oxygen loss at elevated temperatures, and the effect that these have on the structure and properties of the materials.
• Novel Cathode and Anode Materials for Rechargeable Lithium-ion Batteries. Projects have looked at the electrochemical performance of a variety of spinel and rock salt structured materials where lithium can both be inserted into, and extracted from, the structure. This gives an unusual and interesting set of materials which can act both as cathode and anode materials in Lithium-ion Batteries.
• Non-ambient diffraction studies. Interests in phase transformations, order-disorder phenomena and reversible oxygen loss have often encouraged projects that utilise high and low temperature and/or high pressure studies using both in-house x-ray and external neutron diffraction facilities.

Current research and responsibilities

As the manager of the Department of Materials Science & Engineering’s X-ray Diffraction Small Research Facility, Nik has the following responsibilities:

• Management and administration of the Small Research Facility.
• Facilitation of maintenance of X-ray diffraction instrumentation and associated support facilities accessed by more than 150 currently registered users.
• Provision of training in use of XRD equipment and data analysis, including structural solution by Rietveld refinement.
• Departmental Radiation Protection Supervisor
• Main contact for industrial consultancy work. This includes, but is not restricted to Retained Austenite content measurements, Phase analysis work, etc.

Nik also has joint responsibility for supervision of a number of postgraduate students and for conducting his own PDRA-level research programme, mainly focussing on crystal structure solution in new ceramic oxide phases.

Key publications

• Reeves-McLaren N, Smith RI, West AR, Lithium-ion conduction pathways in complex lithium spinels Li₂MGe₃O₈ (M = Ni or Zn), Chemistry of Materials (2011).
• Reeves-McLaren N, Ferrarelli MC, Tung YW, Sinclair DC, West AR, Synthesis, structure and electrical properties of Cu_3.21Ti_1.16Nb_2.63O₁₂ and the CuO_x–TiO₂–Nb₂O₅ pseudoternary phase diagram, Journal of Solid State Chemistry, 184: 1813-1819 (2011).
• Gillie LJ, de Souza SA, Sheptyakov D, Reeves-McLaren N, Pasero D, West AR, Synthesis, structural characterization and Li+ ion conductivity of a new vanado-molybdate phase, LiMg₃VMo₂O₁₂, Journal of Solid State Chemistry, 183: 2589-2597 (2011).
• Varghese J, Joseph T, Sebastian MT, Reeves-McLaren N, Feteira A, Crystal structure and microwave dielectric properties of LaLuO₃ ceramics, Journal of the American Ceramic Society, 93: 2960-2963 (2010).
• Wu H, Reeves-McLaren N, Pokorny J, Yarwood J, West AR, Polymorphism, Phase Transitions, and Thermal Stability of L-Pyroglutamic Acid, Crystal Growth and Design, 10: 3141-3148 (2010).
• Wu H, Reeves-McLaren N, Jones S, Ristic RI, Fairclough JPA, West AR, Polymorphism, Phase Transitions, and Thermal Stability of L-Pyroglutamic Acid, Crystal Growth and Design, 10: 988-994 (2010).
• Pasero D, Reeves N, Pralong V, West AR, Oxygen nonstoichiometry and phase transitions in LiMn_1.5Ni_0.5O_4-δ, Journal of the Electrochemical Society, 155(4), A282-A291. (2008).
• Reeves N, Pasero D, West AR, Order-disorder transition in the complex lithium spinel Li₂CoTi₃O₈, Journal of Solid State Chemistry, 180: 1894–1901. (2007).
• Pasero D, Reeves N, Gillie L, Pralong V, West AR, Oxygen stoichiometry-structure-property correlations in Li_2/3[Mn_2/3Ni_1/3]O_2-δ with O3 structure, Journal of the Electrochemical Society, 154: A760-A769 (2007).
• Pasero D, Reeves N, Gillie LJ, West AR, Variable oxygen stoichiometry in layered rock salt cathodes, Li_x(Mn,Ni)O₂, depending on synthesis conditions, Journal of Power Sources, 174: 1078-1081.
• Pasero D, de Souza S, Reeves N, West AR, Oxygen content and electrochemical activity of LiCoMnO_4-δ, Journal of Materials Chemistry, 15(41): 4435-4440. (2005).
• Pasero D, Reeves N, West AR, Co-doped Mn₃O₄: a possible anode material for lithium batteries, Journal of Power Sources, 141(1): 156-158. (2005).
• Reeves N, Kirk CA, West AR,‘Reversible spinel to rock salt transition in LiCoMnO_d by oxygen (de) intercalation, Journal of Materials Chemistry, 11(2): 249-250. (2001).