This thesis describes the synthesis, properties and structural characterisation of Mg\(^2\)\(^+\), Mn\(^2\)\(^+\)and Ti\(^4\)\(^+\) pyrophosphates and Li and V substituted analogues. α and β polymorphs of MgH\(_2\)P\(_2\)O\(_7\), were isolated by a novel acid melt synthetic route. Both polymorphs crystallised in monoclinic space groups, with α-MgH\(_2\)P\(_2\)O\(_7\) isostructural with NiH\(_2\)P\(_2\)O\(_7\) and β-MgH\(_2\)P\(_2\)O\(_7\) isostructural with CaH\(_2\)P\(_2\)O\(_7\). Rietveld refinements of NPD data gave excellent fits to both structural models. MgLi\(_0\)\(_.\)\(_8\)H\(_1\)\(_.\)\(_2\)P\(_2\)O\(_7\)was also isolated with Rietveld refinement suggesting two similar possible structural models. MnH\(_2\)P\(_2\)O\(_7\), a structural polymorph of β-MgH\(_2\)P\(_2\)O\(_7\) was also synthesised via a similar route. Magnetic analysis revealed MnH\(_2\)P\(_2\)O\(_7\) to be paramagnetic, with a small antiferromagnetic component. Incorporation of Li was again achieved via the addition of lithium carbonate during synthesis. Rietveld refinement of NPD data suggests a similar structure to that of MnH\(_2\)P\(_2\)O\(_7\) and a composition of MnLi\(_0\)\(_.\)\(_5\)H\(_1\)\(_.\)\(_5\)P\(_2\)O\(_7\). A metastable polymorph of TiP2O7 has been successfully synthesised at low temperature and adopts a structure similar to the ideal cubic structure. Incorporation of vanadium resulted in an expansion of the unit cell. Both phases undergo a phase transition above 275°C to the ideal cubic structure. Addition of vanadium results in an unusual uniform spherical morphology unseen in parent phase.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:633380 |
| Date | January 2014 |
| Creators | Baker, Annabelle R. |
| Publisher | University of Birmingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://etheses.bham.ac.uk//id/eprint/5524/ |
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