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Prussian blue analogues (PBAs), A_xM[M’(CN)₆]_1–y·zH₂O, are used in many different applications, such as energy storage, due to their tunable composition and structural diversity. To understand the material properties, it is important to accurately determine the composition and atomic structure of these materials. Determining the composition of iron-based PBAs is challenging due to the interdependent relationship between the three compositional parameters namely the sodium (A_x), water (z), and [Fe(CN)₆]^n– (y) vacancy content. In addition, the atomic structure depends on the composition leading to a rich structural landscape, which further influences the material properties. This thesis presents a comprehensive strategy for characterizing the composition and atomic structure of iron-based PBAs by applying different characterization techniques. Firstly, it was shown that to accurately determine the composition of iron-based PBAs, it is crucial to combine multiple characterization techniques in combination. In particular, Mössbauer spectroscopy proved to be a key technique for accurately determining the vacancy content in iron-based PBAs, where both metal sites (M and M’) are occupied by iron. Furthermore, positron annihilation lifetime spectroscopy was explored as a potential method for determining the internal porosity in PBAs. A correlation between the average positron lifetime and varying PBA compositions was found and is compared to other standard characterization techniques. Secondly, the impact of the synthesis method of Na₂Fe[Fe(CN)₆]·zH₂O was studied using X-ray and neutron diffraction. Independent of the synthesis method, it was found that a P2₁/n phase exists at room temperature, which transitions to an R-3 phase upon heating to 40 °C. The two structures were differentiated in terms of the octahedral tilting system and sodium-ion displacements. These results were compared to the structure of the dehydrated material. In addition, it was found that there is a significant difference in the rate and magnitude of thermal expansion of the hydrated relative to the dehydrated material.

Prussian blue analogues (PBAs), A_xM[M’(CN)₆]_1–y·zG, are used in many different applications, such as energy storage, due to their tunable composition and structural diversity. To understand the material properties, it is important to accurately determine the composition and atomic structure of these materials. However, this is challenging due to the interdependent relationship between the three compositional parameters: the alkali cation (A_x), water (z), and [M’(CN)₆]^n– (y) vacancy content. Furthermore, the atomic structure depends on the composition, which leads to a rich structural landscape that further influences the material properties. This thesis presents a comprehensive strategy for characterizing the composition and atomic structure of iron- and sodium-based PBAs. To accurately determine the composition of iron-based PBAs, it was found that a combination of multiple characterization techniques is needed; especially Mössbauer spectroscopy proved vital for accurately determining the vacancy content. Neutron diffraction, neutron total scattering, quasi-elastic neutron scattering, and inelastic neutron scattering were applied to probe the local and average structures as well as the dynamics of the water in PBAs as a function of sodium content and temperature. It was found that the PBA system is more dynamic than previously thought, and that the sodium and water can occupy a broad range of positions, which change with temperature. The material becomes more disordered upon dehydration or when the sodium content is lowered. Additionally, distortions of the PBA framework proved to be an inherent property of these materials. This work also demonstrates that neutron diffraction alone is insufficient to describe sodium and water positions, confirming the need for local probes such as total scattering and inelastic neutron scattering. These findings highlight the importance of proper compositional, structural, and dynamical characterization using multiple techniques and lay the groundwork for further development of new PBAs.