Combining solid-state NMR spectroscopy and first-principles calculations to study disorder in inorganic solids

This thesis focuses on the combination of solid-state nuclear magnetic resonance (NMR) spectroscopy with first-principles calculations, to describe, model and understand the different types of structural disorder present in a set of different inorganic materials. Initially, sodium intercalation into an organic anode was studied, where different computational methods for the generation of structural models for the sodiated phase were used and combined with experimental data to propose a model that could describe the sodiated structure. A second study explored the surface of MOF nanoparticles that had been functionalised with folic acid with the help of dynamic nuclear polarisation. By performing recoupling experiments between deuterated versions of the MOF and the folic acid, it was possible to describe the binding orientation of the folic acid on the surface. Further work studied the exchange of the bridging hydroxyl groups for methoxy groups in two novel gallium and indium MOF frameworks. It was possible to confirm the attachment of the methoxy groups to the MOF framework, understand the structural changes caused by this, and quantify the methoxylation fraction. The disorder caused by the distribution of niobium and tantalum atoms in an oxide with the rynersonite structure was studied using ¹⁷O isotopic enrichment, which proved the presence of Nb-O-Ta bonds and the absence of any significant ordering or pairing of the Nb and Ta atoms. Finally, potassium substitution into NaNbO₃ was investigated. The effect of K substitution on the polymorphism and its distribution at different levels of substitution was studied, showing no evidence for preferential site substitution, but suggesting that there is a tendency to form K-rich regions in the material.