Details of Grant 

EPSRC Reference:	EP/H048642/1
Title:	Cryogenic static and magic-angle spinning nuclear magnetic resonance on superconductors
Principal Investigator:	Carravetta, Dr M
Other Investigators:
Researcher Co-Investigators:
Project Partners:
Department:	Sch of Chemistry
Organisation:	University of Southampton
Scheme:	First Grant - Revised 2009
Starts:	20 September 2010	Ends:	19 March 2012	Value (£):	100,112
EPSRC Research Topic Classifications:	Analytical Science Instrumentation Eng. & Dev. Materials Characterisation
EPSRC Industrial Sector Classifications:	Energy
Related Grants:
Panel History:	Panel Date Panel Name Outcome 24 Feb 2010 Physical Sciences Panel - Chemistry Announced
Summary on Grant Application Form
This project is concerned with the cryogenic nuclear magnetic resonance (NMR) on superconductors in static and rotating solids. Conventional conductors allow electric current to flow through them, although some of the energy is dissipated into heat as the current encounters a resistance. For temperatures below the critical temperature (Tc) a superconductor exhibits no electrical resistance for DC currents. The lack of energy dissipation makes superconductors very interesting for a wide range of applications in science and medicine (magnets for NMR and MRI, particle accelerators, generators), and potentially useful for high current leads if lossless and stable in a useful temperature regime. The discovery of new high temperature superconductor (HTS) materials is often accidental, and the accepted theory for superconductivity does not fully describe HTS. More information is needed to enable the design of stable materials with large critical fields and with Tc closer to room temperature. Detailed studies relating precise experimental observations to the local structure and to the calculated parameters, as in this proposal, are therefore very valuable. NMR provides detailed information on the local structure and dynamics, with atomic resolution, in a wide temperature range. Solid state NMR spectra of static samples are often very broad, so that site specific information may be entangled and difficult to separate. For certain nuclei, the NMR interactions are so large that static wideline spectra are needed. For many other nuclei, improved resolution and signal to noise are achieved by rotating the sample about the magic-angle . Magic-angle spinning (MAS) can resolve inequivalent chemical sites, and is routinely applied mostly for studies above 160 K due to technical limitations. In the world, there are only a few MAS NMR probes operating below 70 K (cryoMAS). In the UK, a 14 T cryoMAS system is available uniquely in Southampton. For superconductors, it is essential to perform experiments in a wide temperature range, but expecially at cryogenic temperatures, because much of the interesting physics occurs below 150 K. Experimental data provided by static and MAS NMR experiments at several fields (important since Tc depends on magnetic fields), between 2 K and 300 K will be used, together with the information from ab initio calculations, to achieve a consistent interpretation of NMR properties in terms of geometrical and dynamical constraints, therefore providing insight into the electronic structure (density of states of the Fermi levels, energy gap). Nobody has ever undertaken such a systematic study of HTS combining cryostatic, cryoMAS NMR and ab initio methods. The impact of our investigation will be significant in the field. High quality data will be obtained on fine powder HTS samples, which are most relevant for technological applications, but more difficult to characterise. Problems related to structural disorder, grain boundaries, the role of oxidation and doping will be among the targets of our NMR studies, and will complement information obtained using other techniques. The improvement of structural models will help to draw guidelines for the next generation of HTS. Specific targets will be: (1) Preliminary studies on well characterised model compounds to tune up experimental conditions, data analysis and calculations. (2) Osmates prepared in UoS with well characterised electronic properties. NMR will address the unsolved questions about rattling motion of the alkali ions. (3) pure and doped MgB2, to address the structural role of the doping and the effects of the grain boundaries. (4) Alkali fullerides and derivatives with molecular hydrogen inside the fullerene cage. From my previous NMR work on pure H2@C60, it is clear that H2 has a significant effect and changes the dynamics and phase transition of C60.
Key Findings
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Potential use in non-academic contexts
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Organisation Website:	http://www.soton.ac.uk