Chaotic Simplicity: A Systematic Investigation of the Structure-Property Relationships in Simple ABO4 Metal Oxides

Abstract

The replacement of carbon-emitting energy sources with cleaner alternatives on an industrial scale is regarded as a critical priority for limiting the effects of anthropogenic climate change. The global economy needs ways to limit the carbon emissions produced from modern processes, such as energy generation and infrastructure manufacturing. Metal oxides with the ABO4 structure type have found application in a variety of carbon-neutral processes due to the diverse array of chemical substitutions that can be made into their structure, leading to different applications and functionalities. These include LaNbO4 as a ceramic electrolyte for solid oxide fuel cells, BiVO4 and PbWO4 as catalysts for photocatalytic water splitting and clean hydrogen production, and ATcO4 salts as matrices for safely storing radioactive waste.

This dissertation focuses on understanding and developing structure-functionality relationships within this material class. Using a combination of synchrotron X-ray and neutron powder diffraction, an understanding can be established of their long-range average structure. This is followed by a study of their short-range local structure using X-ray and neutron total scattering techniques, where pair distribution function analysis is used to identify and quantify local distortions and disordering processes that occur on an atom-by-atom scale. Finally, the accurate establishment of these structures across different length scales is used to improve their application as functional energy materials, where engineering choices have been identified to inform the designing and manufacturing of the next generation of these devices.