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Title: Cooling rapidly and relaxing slowly with 4f ions
Author: Sharples, Joseph William
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2013
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Anisotropic magnetic materials have been proposed over the past twenty years or so as candidates for high density storage, so-called Single-Molecule Magnets (SMMs). These may in future be used to store data at the level of an individual molecule. Separately, isotropic materials may be harnessed for their large magnetocaloric effect which enables them to be used as refrigerants. This can potentially replace the increasingly rare and therefore expensive 3He and 4He currently employed either separately or in 3He-4He dilution refrigerators. This thesis examines the use of lanthanide(III) ions for these applications, by detailing the synthesis, characterisation and performance of three new classes of zero-dimensional compounds, {LnIII2}, {LnIII2ZnII4} and {LnIII7}. These are assessed by several techniques including SQUID magnetometry, heat capacity measurements luminescence spectroscopy, Electron Paramagnetic Resonance and ab initio calculations. In doing so we extended the use of a tripodal ligand widely employed in 3d chemistry to 4f ions, and found only the second 3d-4f phosphonate SMM. Investigating several members of a known three-dimensional lanthanide(III) polymer, {LnIII}n, showed the isotropic gadolinium(III) analogue is one of the very best of all known magnetic refrigerants in the low-temperature regime.
Supervisor: Collison, David Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Magnetocaloric ; SMM ; Gadolinium ; Dysprosium ; Lanthanide ; Magnetism